mirror of
https://github.com/mjl-/mox.git
synced 2024-12-26 16:33:47 +03:00
61bae75228
- dmarc reports: add a cid to the log line about one run of sending reports, and log line for each report - in smtpclient, also handle tls errors from the first read after a handshake. we appear to sometimes get tls alerts about bad certificates on the first read. - for messages to dmarc/tls reporting addresses that we think should/can not be processed as reports, add an X-Mox- header explaining the reason. - tls reports: send report messages with From address of postmaster at an actually configured domain for the mail host. and only send reports when dkim signing is configured for that domain. the domain is also the submitter domain. the rfc seems to require dkim-signing with an exact match with the message from and submitter. - for incoming tls reports, in the smtp server, we do allow a dkim-signature domain that is higher-level (up to publicsuffix) of the message from domain. so we are stricter in what we send than what we receive.
2905 lines
103 KiB
Go
2905 lines
103 KiB
Go
// Package smtpserver implements an SMTP server for submission and incoming delivery of mail messages.
|
|
package smtpserver
|
|
|
|
import (
|
|
"bufio"
|
|
"bytes"
|
|
"context"
|
|
"crypto/md5"
|
|
"crypto/rsa"
|
|
"crypto/sha1"
|
|
"crypto/sha256"
|
|
"crypto/tls"
|
|
"encoding/base64"
|
|
"errors"
|
|
"fmt"
|
|
"hash"
|
|
"io"
|
|
"math"
|
|
"net"
|
|
"net/textproto"
|
|
"os"
|
|
"runtime/debug"
|
|
"sort"
|
|
"strconv"
|
|
"strings"
|
|
"sync"
|
|
"time"
|
|
|
|
"golang.org/x/exp/maps"
|
|
|
|
"github.com/prometheus/client_golang/prometheus"
|
|
"github.com/prometheus/client_golang/prometheus/promauto"
|
|
|
|
"github.com/mjl-/bstore"
|
|
|
|
"github.com/mjl-/mox/config"
|
|
"github.com/mjl-/mox/dkim"
|
|
"github.com/mjl-/mox/dmarc"
|
|
"github.com/mjl-/mox/dmarcdb"
|
|
"github.com/mjl-/mox/dmarcrpt"
|
|
"github.com/mjl-/mox/dns"
|
|
"github.com/mjl-/mox/dsn"
|
|
"github.com/mjl-/mox/iprev"
|
|
"github.com/mjl-/mox/message"
|
|
"github.com/mjl-/mox/metrics"
|
|
"github.com/mjl-/mox/mlog"
|
|
"github.com/mjl-/mox/mox-"
|
|
"github.com/mjl-/mox/moxio"
|
|
"github.com/mjl-/mox/moxvar"
|
|
"github.com/mjl-/mox/publicsuffix"
|
|
"github.com/mjl-/mox/queue"
|
|
"github.com/mjl-/mox/ratelimit"
|
|
"github.com/mjl-/mox/scram"
|
|
"github.com/mjl-/mox/smtp"
|
|
"github.com/mjl-/mox/spf"
|
|
"github.com/mjl-/mox/store"
|
|
"github.com/mjl-/mox/tlsrptdb"
|
|
)
|
|
|
|
// Most logging should be done through conn.log* functions.
|
|
// Only use log in contexts without connection.
|
|
var xlog = mlog.New("smtpserver")
|
|
|
|
// We use panic and recover for error handling while executing commands.
|
|
// These errors signal the connection must be closed.
|
|
var errIO = errors.New("io error")
|
|
|
|
// If set, regular delivery/submit is sidestepped, email is accepted and
|
|
// delivered to the account named mox.
|
|
var Localserve bool
|
|
|
|
var limiterConnectionRate, limiterConnections *ratelimit.Limiter
|
|
|
|
// For delivery rate limiting. Variable because changed during tests.
|
|
var limitIPMasked1MessagesPerMinute int = 500
|
|
var limitIPMasked1SizePerMinute int64 = 1000 * 1024 * 1024
|
|
|
|
func init() {
|
|
// Also called by tests, so they don't trigger the rate limiter.
|
|
limitersInit()
|
|
}
|
|
|
|
func limitersInit() {
|
|
mox.LimitersInit()
|
|
// todo future: make these configurable
|
|
limiterConnectionRate = &ratelimit.Limiter{
|
|
WindowLimits: []ratelimit.WindowLimit{
|
|
{
|
|
Window: time.Minute,
|
|
Limits: [...]int64{300, 900, 2700},
|
|
},
|
|
},
|
|
}
|
|
limiterConnections = &ratelimit.Limiter{
|
|
WindowLimits: []ratelimit.WindowLimit{
|
|
{
|
|
Window: time.Duration(math.MaxInt64), // All of time.
|
|
Limits: [...]int64{30, 90, 270},
|
|
},
|
|
},
|
|
}
|
|
}
|
|
|
|
var (
|
|
// Delays for bad/suspicious behaviour. Zero during tests.
|
|
badClientDelay = time.Second // Before reads and after 1-byte writes for probably spammers.
|
|
authFailDelay = time.Second // Response to authentication failure.
|
|
unknownRecipientsDelay = 5 * time.Second // Response when all recipients are unknown.
|
|
firstTimeSenderDelayDefault = 15 * time.Second // Before accepting message from first-time sender.
|
|
)
|
|
|
|
type codes struct {
|
|
code int
|
|
secode string // Enhanced code, but without the leading major int from code.
|
|
}
|
|
|
|
var (
|
|
metricConnection = promauto.NewCounterVec(
|
|
prometheus.CounterOpts{
|
|
Name: "mox_smtpserver_connection_total",
|
|
Help: "Incoming SMTP connections.",
|
|
},
|
|
[]string{
|
|
"kind", // "deliver" or "submit"
|
|
},
|
|
)
|
|
metricCommands = promauto.NewHistogramVec(
|
|
prometheus.HistogramOpts{
|
|
Name: "mox_smtpserver_command_duration_seconds",
|
|
Help: "SMTP server command duration and result codes in seconds.",
|
|
Buckets: []float64{0.001, 0.005, 0.01, 0.05, 0.100, 0.5, 1, 5, 10, 20, 30, 60, 120},
|
|
},
|
|
[]string{
|
|
"kind", // "deliver" or "submit"
|
|
"cmd",
|
|
"code",
|
|
"ecode",
|
|
},
|
|
)
|
|
metricDelivery = promauto.NewCounterVec(
|
|
prometheus.CounterOpts{
|
|
Name: "mox_smtpserver_delivery_total",
|
|
Help: "SMTP incoming message delivery from external source, not submission. Result values: delivered, reject, unknownuser, accounterror, delivererror. Reason indicates why a message was rejected/accepted.",
|
|
},
|
|
[]string{
|
|
"result",
|
|
"reason",
|
|
},
|
|
)
|
|
// Similar between ../webmail/webmail.go:/metricSubmission and ../smtpserver/server.go:/metricSubmission
|
|
metricSubmission = promauto.NewCounterVec(
|
|
prometheus.CounterOpts{
|
|
Name: "mox_smtpserver_submission_total",
|
|
Help: "SMTP server incoming submission results, known values (those ending with error are server errors): ok, badmessage, badfrom, badheader, messagelimiterror, recipientlimiterror, localserveerror, queueerror.",
|
|
},
|
|
[]string{
|
|
"result",
|
|
},
|
|
)
|
|
metricServerErrors = promauto.NewCounterVec(
|
|
prometheus.CounterOpts{
|
|
Name: "mox_smtpserver_errors_total",
|
|
Help: "SMTP server errors, known values: dkimsign, queuedsn.",
|
|
},
|
|
[]string{
|
|
"error",
|
|
},
|
|
)
|
|
)
|
|
|
|
var jitterRand = mox.NewPseudoRand()
|
|
|
|
func durationDefault(delay *time.Duration, def time.Duration) time.Duration {
|
|
if delay == nil {
|
|
return def
|
|
}
|
|
return *delay
|
|
}
|
|
|
|
// Listen initializes network listeners for incoming SMTP connection.
|
|
// The listeners are stored for a later call to Serve.
|
|
func Listen() {
|
|
names := maps.Keys(mox.Conf.Static.Listeners)
|
|
sort.Strings(names)
|
|
for _, name := range names {
|
|
listener := mox.Conf.Static.Listeners[name]
|
|
|
|
var tlsConfig *tls.Config
|
|
if listener.TLS != nil {
|
|
tlsConfig = listener.TLS.Config
|
|
}
|
|
|
|
maxMsgSize := listener.SMTPMaxMessageSize
|
|
if maxMsgSize == 0 {
|
|
maxMsgSize = config.DefaultMaxMsgSize
|
|
}
|
|
|
|
if listener.SMTP.Enabled {
|
|
hostname := mox.Conf.Static.HostnameDomain
|
|
if listener.Hostname != "" {
|
|
hostname = listener.HostnameDomain
|
|
}
|
|
port := config.Port(listener.SMTP.Port, 25)
|
|
for _, ip := range listener.IPs {
|
|
firstTimeSenderDelay := durationDefault(listener.SMTP.FirstTimeSenderDelay, firstTimeSenderDelayDefault)
|
|
listen1("smtp", name, ip, port, hostname, tlsConfig, false, false, maxMsgSize, false, listener.SMTP.RequireSTARTTLS, !listener.SMTP.NoRequireTLS, listener.SMTP.DNSBLZones, firstTimeSenderDelay)
|
|
}
|
|
}
|
|
if listener.Submission.Enabled {
|
|
hostname := mox.Conf.Static.HostnameDomain
|
|
if listener.Hostname != "" {
|
|
hostname = listener.HostnameDomain
|
|
}
|
|
port := config.Port(listener.Submission.Port, 587)
|
|
for _, ip := range listener.IPs {
|
|
listen1("submission", name, ip, port, hostname, tlsConfig, true, false, maxMsgSize, !listener.Submission.NoRequireSTARTTLS, !listener.Submission.NoRequireSTARTTLS, true, nil, 0)
|
|
}
|
|
}
|
|
|
|
if listener.Submissions.Enabled {
|
|
hostname := mox.Conf.Static.HostnameDomain
|
|
if listener.Hostname != "" {
|
|
hostname = listener.HostnameDomain
|
|
}
|
|
port := config.Port(listener.Submissions.Port, 465)
|
|
for _, ip := range listener.IPs {
|
|
listen1("submissions", name, ip, port, hostname, tlsConfig, true, true, maxMsgSize, true, true, true, nil, 0)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
var servers []func()
|
|
|
|
func listen1(protocol, name, ip string, port int, hostname dns.Domain, tlsConfig *tls.Config, submission, xtls bool, maxMessageSize int64, requireTLSForAuth, requireTLSForDelivery, requireTLS bool, dnsBLs []dns.Domain, firstTimeSenderDelay time.Duration) {
|
|
addr := net.JoinHostPort(ip, fmt.Sprintf("%d", port))
|
|
if os.Getuid() == 0 {
|
|
xlog.Print("listening for smtp", mlog.Field("listener", name), mlog.Field("address", addr), mlog.Field("protocol", protocol))
|
|
}
|
|
network := mox.Network(ip)
|
|
ln, err := mox.Listen(network, addr)
|
|
if err != nil {
|
|
xlog.Fatalx("smtp: listen for smtp", err, mlog.Field("protocol", protocol), mlog.Field("listener", name))
|
|
}
|
|
if xtls {
|
|
ln = tls.NewListener(ln, tlsConfig)
|
|
}
|
|
|
|
serve := func() {
|
|
for {
|
|
conn, err := ln.Accept()
|
|
if err != nil {
|
|
xlog.Infox("smtp: accept", err, mlog.Field("protocol", protocol), mlog.Field("listener", name))
|
|
continue
|
|
}
|
|
resolver := dns.StrictResolver{} // By leaving Pkg empty, it'll be set by each package that uses the resolver, e.g. spf/dkim/dmarc.
|
|
go serve(name, mox.Cid(), hostname, tlsConfig, conn, resolver, submission, xtls, maxMessageSize, requireTLSForAuth, requireTLSForDelivery, requireTLS, dnsBLs, firstTimeSenderDelay)
|
|
}
|
|
}
|
|
|
|
servers = append(servers, serve)
|
|
}
|
|
|
|
// Serve starts serving on all listeners, launching a goroutine per listener.
|
|
func Serve() {
|
|
for _, serve := range servers {
|
|
go serve()
|
|
}
|
|
}
|
|
|
|
type conn struct {
|
|
cid int64
|
|
|
|
// OrigConn is the original (TCP) connection. We'll read from/write to conn, which
|
|
// can be wrapped in a tls.Server. We close origConn instead of conn because
|
|
// closing the TLS connection would send a TLS close notification, which may block
|
|
// for 5s if the server isn't reading it (because it is also sending it).
|
|
origConn net.Conn
|
|
conn net.Conn
|
|
|
|
tls bool
|
|
extRequireTLS bool // Whether to announce and allow the REQUIRETLS extension.
|
|
resolver dns.Resolver
|
|
r *bufio.Reader
|
|
w *bufio.Writer
|
|
tr *moxio.TraceReader // Kept for changing trace level during cmd/auth/data.
|
|
tw *moxio.TraceWriter
|
|
slow bool // If set, reads are done with a 1 second sleep, and writes are done 1 byte at a time, to keep spammers busy.
|
|
lastlog time.Time // Used for printing the delta time since the previous logging for this connection.
|
|
submission bool // ../rfc/6409:19 applies
|
|
tlsConfig *tls.Config
|
|
localIP net.IP
|
|
remoteIP net.IP
|
|
hostname dns.Domain
|
|
log *mlog.Log
|
|
maxMessageSize int64
|
|
requireTLSForAuth bool
|
|
requireTLSForDelivery bool // If set, delivery is only allowed with TLS (STARTTLS), except if delivery is to a TLS reporting address.
|
|
cmd string // Current command.
|
|
cmdStart time.Time // Start of current command.
|
|
ncmds int // Number of commands processed. Used to abort connection when first incoming command is unknown/invalid.
|
|
dnsBLs []dns.Domain
|
|
firstTimeSenderDelay time.Duration
|
|
|
|
// If non-zero, taken into account during Read and Write. Set while processing DATA
|
|
// command, we don't want the entire delivery to take too long.
|
|
deadline time.Time
|
|
|
|
hello dns.IPDomain // Claimed remote name. Can be ip address for ehlo.
|
|
ehlo bool // If set, we had EHLO instead of HELO.
|
|
|
|
authFailed int // Number of failed auth attempts. For slowing down remote with many failures.
|
|
username string // Only when authenticated.
|
|
account *store.Account // Only when authenticated.
|
|
|
|
// We track good/bad message transactions to disconnect spammers trying to guess addresses.
|
|
transactionGood int
|
|
transactionBad int
|
|
|
|
// Message transaction.
|
|
mailFrom *smtp.Path
|
|
requireTLS *bool // MAIL FROM with REQUIRETLS set.
|
|
has8bitmime bool // If MAIL FROM parameter BODY=8BITMIME was sent. Required for SMTPUTF8.
|
|
smtputf8 bool // todo future: we should keep track of this per recipient. perhaps only a specific recipient requires smtputf8, e.g. due to a utf8 localpart. we should decide ourselves if the message needs smtputf8, e.g. due to utf8 header values.
|
|
recipients []rcptAccount
|
|
}
|
|
|
|
type rcptAccount struct {
|
|
rcptTo smtp.Path
|
|
local bool // Whether recipient is a local user.
|
|
|
|
// Only valid for local delivery.
|
|
accountName string
|
|
destination config.Destination
|
|
canonicalAddress string // Optional catchall part stripped and/or lowercased.
|
|
}
|
|
|
|
func isClosed(err error) bool {
|
|
return errors.Is(err, errIO) || moxio.IsClosed(err)
|
|
}
|
|
|
|
// completely reset connection state as if greeting has just been sent.
|
|
// ../rfc/3207:210
|
|
func (c *conn) reset() {
|
|
c.ehlo = false
|
|
c.hello = dns.IPDomain{}
|
|
c.username = ""
|
|
if c.account != nil {
|
|
err := c.account.Close()
|
|
c.log.Check(err, "closing account")
|
|
}
|
|
c.account = nil
|
|
c.rset()
|
|
}
|
|
|
|
// for rset command, and a few more cases that reset the mail transaction state.
|
|
// ../rfc/5321:2502
|
|
func (c *conn) rset() {
|
|
c.mailFrom = nil
|
|
c.requireTLS = nil
|
|
c.has8bitmime = false
|
|
c.smtputf8 = false
|
|
c.recipients = nil
|
|
}
|
|
|
|
func (c *conn) earliestDeadline(d time.Duration) time.Time {
|
|
e := time.Now().Add(d)
|
|
if !c.deadline.IsZero() && c.deadline.Before(e) {
|
|
return c.deadline
|
|
}
|
|
return e
|
|
}
|
|
|
|
func (c *conn) xcheckAuth() {
|
|
if c.submission && c.account == nil {
|
|
// ../rfc/4954:623
|
|
xsmtpUserErrorf(smtp.C530SecurityRequired, smtp.SePol7Other0, "authentication required")
|
|
}
|
|
}
|
|
|
|
func (c *conn) xtrace(level mlog.Level) func() {
|
|
c.xflush()
|
|
c.tr.SetTrace(level)
|
|
c.tw.SetTrace(level)
|
|
return func() {
|
|
c.xflush()
|
|
c.tr.SetTrace(mlog.LevelTrace)
|
|
c.tw.SetTrace(mlog.LevelTrace)
|
|
}
|
|
}
|
|
|
|
// setSlow marks the connection slow (or now), so reads are done with 3 second
|
|
// delay for each read, and writes are done at 1 byte per second, to try to slow
|
|
// down spammers.
|
|
func (c *conn) setSlow(on bool) {
|
|
if on && !c.slow {
|
|
c.log.Debug("connection changed to slow")
|
|
} else if !on && c.slow {
|
|
c.log.Debug("connection restored to regular pace")
|
|
}
|
|
c.slow = on
|
|
}
|
|
|
|
// Write writes to the connection. It panics on i/o errors, which is handled by the
|
|
// connection command loop.
|
|
func (c *conn) Write(buf []byte) (int, error) {
|
|
chunk := len(buf)
|
|
if c.slow {
|
|
chunk = 1
|
|
}
|
|
|
|
var n int
|
|
for len(buf) > 0 {
|
|
// We set a single deadline for Write and Read. This may be a TLS connection.
|
|
// SetDeadline works on the underlying connection. If we wouldn't touch the read
|
|
// deadline, and only set the write deadline and do a bunch of writes, the TLS
|
|
// library would still have to do reads on the underlying connection, and may reach
|
|
// a read deadline that was set for some earlier read.
|
|
if err := c.conn.SetDeadline(c.earliestDeadline(30 * time.Second)); err != nil {
|
|
c.log.Errorx("setting deadline for write", err)
|
|
}
|
|
|
|
nn, err := c.conn.Write(buf[:chunk])
|
|
if err != nil {
|
|
panic(fmt.Errorf("write: %s (%w)", err, errIO))
|
|
}
|
|
n += nn
|
|
buf = buf[chunk:]
|
|
if len(buf) > 0 && badClientDelay > 0 {
|
|
mox.Sleep(mox.Context, badClientDelay)
|
|
}
|
|
}
|
|
return n, nil
|
|
}
|
|
|
|
// Read reads from the connection. It panics on i/o errors, which is handled by the
|
|
// connection command loop.
|
|
func (c *conn) Read(buf []byte) (int, error) {
|
|
if c.slow && badClientDelay > 0 {
|
|
mox.Sleep(mox.Context, badClientDelay)
|
|
}
|
|
|
|
// todo future: make deadline configurable for callers, and through config file? ../rfc/5321:3610 ../rfc/6409:492
|
|
// See comment about Deadline instead of individual read/write deadlines at Write.
|
|
if err := c.conn.SetDeadline(c.earliestDeadline(30 * time.Second)); err != nil {
|
|
c.log.Errorx("setting deadline for read", err)
|
|
}
|
|
|
|
n, err := c.conn.Read(buf)
|
|
if err != nil {
|
|
panic(fmt.Errorf("read: %s (%w)", err, errIO))
|
|
}
|
|
return n, err
|
|
}
|
|
|
|
// Cache of line buffers for reading commands.
|
|
// Filled on demand.
|
|
var bufpool = moxio.NewBufpool(8, 2*1024)
|
|
|
|
func (c *conn) readline() string {
|
|
line, err := bufpool.Readline(c.r)
|
|
if err != nil && errors.Is(err, moxio.ErrLineTooLong) {
|
|
c.writecodeline(smtp.C500BadSyntax, smtp.SeProto5Other0, "line too long, smtp max is 512, we reached 2048", nil)
|
|
panic(fmt.Errorf("%s (%w)", err, errIO))
|
|
} else if err != nil {
|
|
panic(fmt.Errorf("%s (%w)", err, errIO))
|
|
}
|
|
return line
|
|
}
|
|
|
|
// Buffered-write command response line to connection with codes and msg.
|
|
// Err is not sent to remote but is used for logging and can be empty.
|
|
func (c *conn) bwritecodeline(code int, secode string, msg string, err error) {
|
|
var ecode string
|
|
if secode != "" {
|
|
ecode = fmt.Sprintf("%d.%s", code/100, secode)
|
|
}
|
|
metricCommands.WithLabelValues(c.kind(), c.cmd, fmt.Sprintf("%d", code), ecode).Observe(float64(time.Since(c.cmdStart)) / float64(time.Second))
|
|
c.log.Debugx("smtp command result", err, mlog.Field("kind", c.kind()), mlog.Field("cmd", c.cmd), mlog.Field("code", fmt.Sprintf("%d", code)), mlog.Field("ecode", ecode), mlog.Field("duration", time.Since(c.cmdStart)))
|
|
|
|
var sep string
|
|
if ecode != "" {
|
|
sep = " "
|
|
}
|
|
|
|
// Separate by newline and wrap long lines.
|
|
lines := strings.Split(msg, "\n")
|
|
for i, line := range lines {
|
|
// ../rfc/5321:3506 ../rfc/5321:2583 ../rfc/5321:2756
|
|
var prelen = 3 + 1 + len(ecode) + len(sep)
|
|
for prelen+len(line) > 510 {
|
|
e := 510 - prelen
|
|
for ; e > 400 && line[e] != ' '; e-- {
|
|
}
|
|
// todo future: understand if ecode should be on each line. won't hurt. at least as long as we don't do expn or vrfy.
|
|
c.bwritelinef("%d-%s%s%s", code, ecode, sep, line[:e])
|
|
line = line[e:]
|
|
}
|
|
spdash := " "
|
|
if i < len(lines)-1 {
|
|
spdash = "-"
|
|
}
|
|
c.bwritelinef("%d%s%s%s%s", code, spdash, ecode, sep, line)
|
|
}
|
|
}
|
|
|
|
// Buffered-write a formatted response line to connection.
|
|
func (c *conn) bwritelinef(format string, args ...any) {
|
|
msg := fmt.Sprintf(format, args...)
|
|
fmt.Fprint(c.w, msg+"\r\n")
|
|
}
|
|
|
|
// Flush pending buffered writes to connection.
|
|
func (c *conn) xflush() {
|
|
c.w.Flush() // Errors will have caused a panic in Write.
|
|
}
|
|
|
|
// Write (with flush) a response line with codes and message. err is not written, used for logging and can be nil.
|
|
func (c *conn) writecodeline(code int, secode string, msg string, err error) {
|
|
c.bwritecodeline(code, secode, msg, err)
|
|
c.xflush()
|
|
}
|
|
|
|
// Write (with flush) a formatted response line to connection.
|
|
func (c *conn) writelinef(format string, args ...any) {
|
|
c.bwritelinef(format, args...)
|
|
c.xflush()
|
|
}
|
|
|
|
var cleanClose struct{} // Sentinel value for panic/recover indicating clean close of connection.
|
|
|
|
func serve(listenerName string, cid int64, hostname dns.Domain, tlsConfig *tls.Config, nc net.Conn, resolver dns.Resolver, submission, tls bool, maxMessageSize int64, requireTLSForAuth, requireTLSForDelivery, requireTLS bool, dnsBLs []dns.Domain, firstTimeSenderDelay time.Duration) {
|
|
var localIP, remoteIP net.IP
|
|
if a, ok := nc.LocalAddr().(*net.TCPAddr); ok {
|
|
localIP = a.IP
|
|
} else {
|
|
// For net.Pipe, during tests.
|
|
localIP = net.ParseIP("127.0.0.10")
|
|
}
|
|
if a, ok := nc.RemoteAddr().(*net.TCPAddr); ok {
|
|
remoteIP = a.IP
|
|
} else {
|
|
// For net.Pipe, during tests.
|
|
remoteIP = net.ParseIP("127.0.0.10")
|
|
}
|
|
|
|
c := &conn{
|
|
cid: cid,
|
|
origConn: nc,
|
|
conn: nc,
|
|
submission: submission,
|
|
tls: tls,
|
|
extRequireTLS: requireTLS,
|
|
resolver: resolver,
|
|
lastlog: time.Now(),
|
|
tlsConfig: tlsConfig,
|
|
localIP: localIP,
|
|
remoteIP: remoteIP,
|
|
hostname: hostname,
|
|
maxMessageSize: maxMessageSize,
|
|
requireTLSForAuth: requireTLSForAuth,
|
|
requireTLSForDelivery: requireTLSForDelivery,
|
|
dnsBLs: dnsBLs,
|
|
firstTimeSenderDelay: firstTimeSenderDelay,
|
|
}
|
|
c.log = xlog.MoreFields(func() []mlog.Pair {
|
|
now := time.Now()
|
|
l := []mlog.Pair{
|
|
mlog.Field("cid", c.cid),
|
|
mlog.Field("delta", now.Sub(c.lastlog)),
|
|
}
|
|
c.lastlog = now
|
|
if c.username != "" {
|
|
l = append(l, mlog.Field("username", c.username))
|
|
}
|
|
return l
|
|
})
|
|
c.tr = moxio.NewTraceReader(c.log, "RC: ", c)
|
|
c.tw = moxio.NewTraceWriter(c.log, "LS: ", c)
|
|
c.r = bufio.NewReader(c.tr)
|
|
c.w = bufio.NewWriter(c.tw)
|
|
|
|
metricConnection.WithLabelValues(c.kind()).Inc()
|
|
c.log.Info("new connection", mlog.Field("remote", c.conn.RemoteAddr()), mlog.Field("local", c.conn.LocalAddr()), mlog.Field("submission", submission), mlog.Field("tls", tls), mlog.Field("listener", listenerName))
|
|
|
|
defer func() {
|
|
c.origConn.Close() // Close actual TCP socket, regardless of TLS on top.
|
|
c.conn.Close() // If TLS, will try to write alert notification to already closed socket, returning error quickly.
|
|
|
|
if c.account != nil {
|
|
err := c.account.Close()
|
|
c.log.Check(err, "closing account")
|
|
c.account = nil
|
|
}
|
|
|
|
x := recover()
|
|
if x == nil || x == cleanClose {
|
|
c.log.Info("connection closed")
|
|
} else if err, ok := x.(error); ok && isClosed(err) {
|
|
c.log.Infox("connection closed", err)
|
|
} else {
|
|
c.log.Error("unhandled panic", mlog.Field("err", x))
|
|
debug.PrintStack()
|
|
metrics.PanicInc(metrics.Smtpserver)
|
|
}
|
|
}()
|
|
|
|
select {
|
|
case <-mox.Shutdown.Done():
|
|
// ../rfc/5321:2811 ../rfc/5321:1666 ../rfc/3463:420
|
|
c.writecodeline(smtp.C421ServiceUnavail, smtp.SeSys3NotAccepting2, "shutting down", nil)
|
|
return
|
|
default:
|
|
}
|
|
|
|
if !limiterConnectionRate.Add(c.remoteIP, time.Now(), 1) {
|
|
c.writecodeline(smtp.C421ServiceUnavail, smtp.SePol7Other0, "connection rate from your ip or network too high, slow down please", nil)
|
|
return
|
|
}
|
|
|
|
// If remote IP/network resulted in too many authentication failures, refuse to serve.
|
|
if submission && !mox.LimiterFailedAuth.CanAdd(c.remoteIP, time.Now(), 1) {
|
|
metrics.AuthenticationRatelimitedInc("submission")
|
|
c.log.Debug("refusing connection due to many auth failures", mlog.Field("remoteip", c.remoteIP))
|
|
c.writecodeline(smtp.C421ServiceUnavail, smtp.SePol7Other0, "too many auth failures", nil)
|
|
return
|
|
}
|
|
|
|
if !limiterConnections.Add(c.remoteIP, time.Now(), 1) {
|
|
c.log.Debug("refusing connection due to many open connections", mlog.Field("remoteip", c.remoteIP))
|
|
c.writecodeline(smtp.C421ServiceUnavail, smtp.SePol7Other0, "too many open connections from your ip or network", nil)
|
|
return
|
|
}
|
|
defer limiterConnections.Add(c.remoteIP, time.Now(), -1)
|
|
|
|
// We register and unregister the original connection, in case c.conn is replaced
|
|
// with a TLS connection later on.
|
|
mox.Connections.Register(nc, "smtp", listenerName)
|
|
defer mox.Connections.Unregister(nc)
|
|
|
|
// ../rfc/5321:964 ../rfc/5321:4294 about announcing software and version
|
|
// Syntax: ../rfc/5321:2586
|
|
// We include the string ESMTP. https://cr.yp.to/smtp/greeting.html recommends it.
|
|
// Should not be too relevant nowadays, but does not hurt and default blackbox
|
|
// exporter SMTP health check expects it.
|
|
c.writelinef("%d %s ESMTP mox %s", smtp.C220ServiceReady, c.hostname.ASCII, moxvar.Version)
|
|
|
|
for {
|
|
command(c)
|
|
|
|
// If another command is present, don't flush our buffered response yet. Holding
|
|
// off will cause us to respond with a single packet.
|
|
n := c.r.Buffered()
|
|
if n > 0 {
|
|
buf, err := c.r.Peek(n)
|
|
if err == nil && bytes.IndexByte(buf, '\n') >= 0 {
|
|
continue
|
|
}
|
|
}
|
|
c.xflush()
|
|
}
|
|
}
|
|
|
|
var commands = map[string]func(c *conn, p *parser){
|
|
"helo": (*conn).cmdHelo,
|
|
"ehlo": (*conn).cmdEhlo,
|
|
"starttls": (*conn).cmdStarttls,
|
|
"auth": (*conn).cmdAuth,
|
|
"mail": (*conn).cmdMail,
|
|
"rcpt": (*conn).cmdRcpt,
|
|
"data": (*conn).cmdData,
|
|
"rset": (*conn).cmdRset,
|
|
"vrfy": (*conn).cmdVrfy,
|
|
"expn": (*conn).cmdExpn,
|
|
"help": (*conn).cmdHelp,
|
|
"noop": (*conn).cmdNoop,
|
|
"quit": (*conn).cmdQuit,
|
|
}
|
|
|
|
func command(c *conn) {
|
|
defer func() {
|
|
x := recover()
|
|
if x == nil {
|
|
return
|
|
}
|
|
err, ok := x.(error)
|
|
if !ok {
|
|
panic(x)
|
|
}
|
|
|
|
if isClosed(err) {
|
|
panic(err)
|
|
}
|
|
|
|
var serr smtpError
|
|
if errors.As(err, &serr) {
|
|
c.writecodeline(serr.code, serr.secode, fmt.Sprintf("%s (%s)", serr.errmsg, mox.ReceivedID(c.cid)), serr.err)
|
|
if serr.printStack {
|
|
debug.PrintStack()
|
|
}
|
|
} else {
|
|
// Other type of panic, we pass it on, aborting the connection.
|
|
c.log.Errorx("command panic", err)
|
|
panic(err)
|
|
}
|
|
}()
|
|
|
|
// todo future: we could wait for either a line or shutdown, and just close the connection on shutdown.
|
|
|
|
line := c.readline()
|
|
t := strings.SplitN(line, " ", 2)
|
|
var args string
|
|
if len(t) == 2 {
|
|
args = " " + t[1]
|
|
}
|
|
cmd := t[0]
|
|
cmdl := strings.ToLower(cmd)
|
|
|
|
// todo future: should we return an error for lines that are too long? perhaps for submission or in a pedantic mode. we would have to take extensions for MAIL into account. ../rfc/5321:3500 ../rfc/5321:3552
|
|
|
|
select {
|
|
case <-mox.Shutdown.Done():
|
|
// ../rfc/5321:2811 ../rfc/5321:1666 ../rfc/3463:420
|
|
c.writecodeline(smtp.C421ServiceUnavail, smtp.SeSys3NotAccepting2, "shutting down", nil)
|
|
panic(errIO)
|
|
default:
|
|
}
|
|
|
|
c.cmd = cmdl
|
|
c.cmdStart = time.Now()
|
|
|
|
p := newParser(args, c.smtputf8, c)
|
|
fn, ok := commands[cmdl]
|
|
if !ok {
|
|
c.cmd = "(unknown)"
|
|
if c.ncmds == 0 {
|
|
// Other side is likely speaking something else than SMTP, send error message and
|
|
// stop processing because there is a good chance whatever they sent has multiple
|
|
// lines.
|
|
c.writecodeline(smtp.C500BadSyntax, smtp.SeProto5Syntax2, "please try again speaking smtp", nil)
|
|
panic(errIO)
|
|
}
|
|
// note: not "command not implemented", see ../rfc/5321:2934 ../rfc/5321:2539
|
|
xsmtpUserErrorf(smtp.C500BadSyntax, smtp.SeProto5BadCmdOrSeq1, "unknown command")
|
|
}
|
|
c.ncmds++
|
|
fn(c, p)
|
|
}
|
|
|
|
// For use in metric labels.
|
|
func (c *conn) kind() string {
|
|
if c.submission {
|
|
return "submission"
|
|
}
|
|
return "smtp"
|
|
}
|
|
|
|
func (c *conn) xneedHello() {
|
|
if c.hello.IsZero() {
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "no ehlo/helo yet")
|
|
}
|
|
}
|
|
|
|
// If smtp server is configured to require TLS for all mail delivery (except to TLS
|
|
// reporting address), abort command.
|
|
func (c *conn) xneedTLSForDelivery(rcpt smtp.Path) {
|
|
// For TLS reports, we allow the message in even without TLS, because there may be
|
|
// TLS interopability problems. ../rfc/8460:316
|
|
if c.requireTLSForDelivery && !c.tls && !isTLSReportRecipient(rcpt) {
|
|
// ../rfc/3207:148
|
|
xsmtpUserErrorf(smtp.C530SecurityRequired, smtp.SePol7Other0, "STARTTLS required for mail delivery")
|
|
}
|
|
}
|
|
|
|
func isTLSReportRecipient(rcpt smtp.Path) bool {
|
|
_, _, dest, err := mox.FindAccount(rcpt.Localpart, rcpt.IPDomain.Domain, false)
|
|
return err == nil && (dest.HostTLSReports || dest.DomainTLSReports)
|
|
}
|
|
|
|
func (c *conn) cmdHelo(p *parser) {
|
|
c.cmdHello(p, false)
|
|
}
|
|
|
|
func (c *conn) cmdEhlo(p *parser) {
|
|
c.cmdHello(p, true)
|
|
}
|
|
|
|
// ../rfc/5321:1783
|
|
func (c *conn) cmdHello(p *parser, ehlo bool) {
|
|
var remote dns.IPDomain
|
|
if c.submission && !moxvar.Pedantic {
|
|
// Mail clients regularly put bogus information in the hostname/ip. For submission,
|
|
// the value is of no use, so there is not much point in annoying the user with
|
|
// errors they cannot fix themselves. Except when in pedantic mode.
|
|
remote = dns.IPDomain{IP: c.remoteIP}
|
|
} else {
|
|
p.xspace()
|
|
if ehlo {
|
|
remote = p.xipdomain(true)
|
|
} else {
|
|
remote = dns.IPDomain{Domain: p.xdomain()}
|
|
|
|
// Verify a remote domain name has an A or AAAA record, CNAME not allowed. ../rfc/5321:722
|
|
cidctx := context.WithValue(mox.Context, mlog.CidKey, c.cid)
|
|
ctx, cancel := context.WithTimeout(cidctx, time.Minute)
|
|
_, _, err := c.resolver.LookupIPAddr(ctx, remote.Domain.ASCII+".")
|
|
cancel()
|
|
if dns.IsNotFound(err) {
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeProto5Other0, "your ehlo domain does not resolve to an IP address")
|
|
}
|
|
// For success or temporary resolve errors, we'll just continue.
|
|
}
|
|
// ../rfc/5321:1827
|
|
// Though a few paragraphs earlier is a claim additional data can occur for address
|
|
// literals (IP addresses), although the ABNF in that document does not allow it.
|
|
// We allow additional text, but only if space-separated.
|
|
if len(remote.IP) > 0 && p.space() {
|
|
p.remainder() // ../rfc/5321:1802 ../rfc/2821:1632
|
|
}
|
|
p.xend()
|
|
}
|
|
|
|
// Reset state as if RSET command has been issued. ../rfc/5321:2093 ../rfc/5321:2453
|
|
c.rset()
|
|
|
|
c.ehlo = ehlo
|
|
c.hello = remote
|
|
|
|
// https://www.iana.org/assignments/mail-parameters/mail-parameters.xhtml
|
|
|
|
c.bwritelinef("250-%s", c.hostname.ASCII)
|
|
c.bwritelinef("250-PIPELINING") // ../rfc/2920:108
|
|
c.bwritelinef("250-SIZE %d", c.maxMessageSize) // ../rfc/1870:70
|
|
// ../rfc/3207:237
|
|
if !c.tls && c.tlsConfig != nil {
|
|
// ../rfc/3207:90
|
|
c.bwritelinef("250-STARTTLS")
|
|
} else if c.extRequireTLS {
|
|
// ../rfc/8689:202
|
|
// ../rfc/8689:143
|
|
c.bwritelinef("250-REQUIRETLS")
|
|
}
|
|
if c.submission {
|
|
// ../rfc/4954:123
|
|
if c.tls || !c.requireTLSForAuth {
|
|
c.bwritelinef("250-AUTH SCRAM-SHA-256 SCRAM-SHA-1 CRAM-MD5 PLAIN")
|
|
} else {
|
|
c.bwritelinef("250-AUTH ")
|
|
}
|
|
}
|
|
c.bwritelinef("250-ENHANCEDSTATUSCODES") // ../rfc/2034:71
|
|
// todo future? c.writelinef("250-DSN")
|
|
c.bwritelinef("250-8BITMIME") // ../rfc/6152:86
|
|
c.bwritecodeline(250, "", "SMTPUTF8", nil) // ../rfc/6531:201
|
|
c.xflush()
|
|
}
|
|
|
|
// ../rfc/3207:96
|
|
func (c *conn) cmdStarttls(p *parser) {
|
|
c.xneedHello()
|
|
p.xend()
|
|
|
|
if c.tls {
|
|
// ../rfc/3207:235
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "already speaking tls")
|
|
}
|
|
if c.account != nil {
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "cannot starttls after authentication")
|
|
}
|
|
|
|
// We don't want to do TLS on top of c.r because it also prints protocol traces: We
|
|
// don't want to log the TLS stream. So we'll do TLS on the underlying connection,
|
|
// but make sure any bytes already read and in the buffer are used for the TLS
|
|
// handshake.
|
|
conn := c.conn
|
|
if n := c.r.Buffered(); n > 0 {
|
|
conn = &moxio.PrefixConn{
|
|
PrefixReader: io.LimitReader(c.r, int64(n)),
|
|
Conn: conn,
|
|
}
|
|
}
|
|
|
|
c.writecodeline(smtp.C220ServiceReady, smtp.SeOther00, "go!", nil)
|
|
tlsConn := tls.Server(conn, c.tlsConfig)
|
|
cidctx := context.WithValue(mox.Context, mlog.CidKey, c.cid)
|
|
ctx, cancel := context.WithTimeout(cidctx, time.Minute)
|
|
defer cancel()
|
|
c.log.Debug("starting tls server handshake")
|
|
if err := tlsConn.HandshakeContext(ctx); err != nil {
|
|
panic(fmt.Errorf("starttls handshake: %s (%w)", err, errIO))
|
|
}
|
|
cancel()
|
|
tlsversion, ciphersuite := mox.TLSInfo(tlsConn)
|
|
c.log.Debug("tls server handshake done", mlog.Field("tls", tlsversion), mlog.Field("ciphersuite", ciphersuite))
|
|
c.conn = tlsConn
|
|
c.tr = moxio.NewTraceReader(c.log, "RC: ", c)
|
|
c.tw = moxio.NewTraceWriter(c.log, "LS: ", c)
|
|
c.r = bufio.NewReader(c.tr)
|
|
c.w = bufio.NewWriter(c.tw)
|
|
|
|
c.reset() // ../rfc/3207:210
|
|
c.tls = true
|
|
}
|
|
|
|
// ../rfc/4954:139
|
|
func (c *conn) cmdAuth(p *parser) {
|
|
c.xneedHello()
|
|
|
|
if !c.submission {
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "authentication only allowed on submission ports")
|
|
}
|
|
if c.account != nil {
|
|
// ../rfc/4954:152
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "already authenticated")
|
|
}
|
|
if c.mailFrom != nil {
|
|
// ../rfc/4954:157
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "authentication not allowed during mail transaction")
|
|
}
|
|
|
|
// todo future: we may want to normalize usernames and passwords, see stringprep in ../rfc/4013:38 and possibly newer mechanisms (though they are opt-in and that may not have happened yet).
|
|
|
|
// For many failed auth attempts, slow down verification attempts.
|
|
// Dropping the connection could also work, but more so when we have a connection rate limiter.
|
|
// ../rfc/4954:770
|
|
if c.authFailed > 3 && authFailDelay > 0 {
|
|
// ../rfc/4954:770
|
|
mox.Sleep(mox.Context, time.Duration(c.authFailed-3)*authFailDelay)
|
|
}
|
|
c.authFailed++ // Compensated on success.
|
|
defer func() {
|
|
// On the 3rd failed authentication, start responding slowly. Successful auth will
|
|
// cause fast responses again.
|
|
if c.authFailed >= 3 {
|
|
c.setSlow(true)
|
|
}
|
|
}()
|
|
|
|
var authVariant string
|
|
authResult := "error"
|
|
defer func() {
|
|
metrics.AuthenticationInc("submission", authVariant, authResult)
|
|
switch authResult {
|
|
case "ok":
|
|
mox.LimiterFailedAuth.Reset(c.remoteIP, time.Now())
|
|
default:
|
|
mox.LimiterFailedAuth.Add(c.remoteIP, time.Now(), 1)
|
|
}
|
|
}()
|
|
|
|
// todo: implement "AUTH LOGIN"? it looks like PLAIN, but without the continuation. it is an obsolete sasl mechanism. an account in desktop outlook appears to go through the cloud, attempting to submit email only with unadvertised and AUTH LOGIN. it appears they don't know "plain".
|
|
|
|
// ../rfc/4954:699
|
|
p.xspace()
|
|
mech := p.xsaslMech()
|
|
|
|
xreadInitial := func() []byte {
|
|
var auth string
|
|
if p.empty() {
|
|
c.writelinef("%d ", smtp.C334ContinueAuth) // ../rfc/4954:205
|
|
// todo future: handle max length of 12288 octets and return proper responde codes otherwise ../rfc/4954:253
|
|
auth = c.readline()
|
|
if auth == "*" {
|
|
// ../rfc/4954:193
|
|
authResult = "aborted"
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5Other0, "authentication aborted")
|
|
}
|
|
} else {
|
|
p.xspace()
|
|
if !moxvar.Pedantic {
|
|
// Windows Mail 16005.14326.21606.0 sends two spaces between "AUTH PLAIN" and the
|
|
// base64 data.
|
|
for p.space() {
|
|
}
|
|
}
|
|
auth = p.remainder()
|
|
if auth == "" {
|
|
// ../rfc/4954:235
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5Syntax2, "missing initial auth base64 parameter after space")
|
|
} else if auth == "=" {
|
|
// ../rfc/4954:214
|
|
auth = "" // Base64 decode below will result in empty buffer.
|
|
}
|
|
}
|
|
buf, err := base64.StdEncoding.DecodeString(auth)
|
|
if err != nil {
|
|
// ../rfc/4954:235
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5Syntax2, "invalid base64: %s", err)
|
|
}
|
|
return buf
|
|
}
|
|
|
|
xreadContinuation := func() []byte {
|
|
line := c.readline()
|
|
if line == "*" {
|
|
authResult = "aborted"
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5Other0, "authentication aborted")
|
|
}
|
|
buf, err := base64.StdEncoding.DecodeString(line)
|
|
if err != nil {
|
|
// ../rfc/4954:235
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5Syntax2, "invalid base64: %s", err)
|
|
}
|
|
return buf
|
|
}
|
|
|
|
switch mech {
|
|
case "PLAIN":
|
|
authVariant = "plain"
|
|
|
|
// ../rfc/4954:343
|
|
// ../rfc/4954:326
|
|
if !c.tls && c.requireTLSForAuth {
|
|
xsmtpUserErrorf(smtp.C538EncReqForAuth, smtp.SePol7EncReqForAuth11, "authentication requires tls")
|
|
}
|
|
|
|
// Password is in line in plain text, so hide it.
|
|
defer c.xtrace(mlog.LevelTraceauth)()
|
|
buf := xreadInitial()
|
|
c.xtrace(mlog.LevelTrace) // Restore.
|
|
plain := bytes.Split(buf, []byte{0})
|
|
if len(plain) != 3 {
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5BadParams4, "auth data should have 3 nul-separated tokens, got %d", len(plain))
|
|
}
|
|
authz := string(plain[0])
|
|
authc := string(plain[1])
|
|
password := string(plain[2])
|
|
|
|
if authz != "" && authz != authc {
|
|
authResult = "badcreds"
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "cannot assume other role")
|
|
}
|
|
|
|
acc, err := store.OpenEmailAuth(authc, password)
|
|
if err != nil && errors.Is(err, store.ErrUnknownCredentials) {
|
|
// ../rfc/4954:274
|
|
authResult = "badcreds"
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", authc), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "bad user/pass")
|
|
}
|
|
xcheckf(err, "verifying credentials")
|
|
|
|
authResult = "ok"
|
|
c.authFailed = 0
|
|
c.setSlow(false)
|
|
c.account = acc
|
|
c.username = authc
|
|
// ../rfc/4954:276
|
|
c.writecodeline(smtp.C235AuthSuccess, smtp.SePol7Other0, "nice", nil)
|
|
|
|
case "CRAM-MD5":
|
|
authVariant = strings.ToLower(mech)
|
|
|
|
p.xempty()
|
|
|
|
// ../rfc/2195:82
|
|
chal := fmt.Sprintf("<%d.%d@%s>", uint64(mox.CryptoRandInt()), time.Now().UnixNano(), mox.Conf.Static.HostnameDomain.ASCII)
|
|
c.writelinef("%d %s", smtp.C334ContinueAuth, base64.StdEncoding.EncodeToString([]byte(chal)))
|
|
|
|
resp := xreadContinuation()
|
|
t := strings.Split(string(resp), " ")
|
|
if len(t) != 2 || len(t[1]) != 2*md5.Size {
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5BadParams4, "malformed cram-md5 response")
|
|
}
|
|
addr := t[0]
|
|
c.log.Debug("cram-md5 auth", mlog.Field("address", addr))
|
|
acc, _, err := store.OpenEmail(addr)
|
|
if err != nil {
|
|
if errors.Is(err, store.ErrUnknownCredentials) {
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", addr), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "bad user/pass")
|
|
}
|
|
}
|
|
xcheckf(err, "looking up address")
|
|
defer func() {
|
|
if acc != nil {
|
|
err := acc.Close()
|
|
c.log.Check(err, "closing account")
|
|
}
|
|
}()
|
|
var ipadhash, opadhash hash.Hash
|
|
acc.WithRLock(func() {
|
|
err := acc.DB.Read(context.TODO(), func(tx *bstore.Tx) error {
|
|
password, err := bstore.QueryTx[store.Password](tx).Get()
|
|
if err == bstore.ErrAbsent {
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", addr), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "bad user/pass")
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
ipadhash = password.CRAMMD5.Ipad
|
|
opadhash = password.CRAMMD5.Opad
|
|
return nil
|
|
})
|
|
xcheckf(err, "tx read")
|
|
})
|
|
if ipadhash == nil || opadhash == nil {
|
|
c.log.Info("cram-md5 auth attempt without derived secrets set, save password again to store secrets", mlog.Field("username", addr))
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", addr), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "bad user/pass")
|
|
}
|
|
|
|
// ../rfc/2195:138 ../rfc/2104:142
|
|
ipadhash.Write([]byte(chal))
|
|
opadhash.Write(ipadhash.Sum(nil))
|
|
digest := fmt.Sprintf("%x", opadhash.Sum(nil))
|
|
if digest != t[1] {
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", addr), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "bad user/pass")
|
|
}
|
|
|
|
authResult = "ok"
|
|
c.authFailed = 0
|
|
c.setSlow(false)
|
|
c.account = acc
|
|
acc = nil // Cancel cleanup.
|
|
c.username = addr
|
|
// ../rfc/4954:276
|
|
c.writecodeline(smtp.C235AuthSuccess, smtp.SePol7Other0, "nice", nil)
|
|
|
|
case "SCRAM-SHA-1", "SCRAM-SHA-256":
|
|
// todo: improve handling of errors during scram. e.g. invalid parameters. should we abort the imap command, or continue until the end and respond with a scram-level error?
|
|
// todo: use single implementation between ../imapserver/server.go and ../smtpserver/server.go
|
|
|
|
authVariant = strings.ToLower(mech)
|
|
var h func() hash.Hash
|
|
if authVariant == "scram-sha-1" {
|
|
h = sha1.New
|
|
} else {
|
|
h = sha256.New
|
|
}
|
|
|
|
// Passwords cannot be retrieved or replayed from the trace.
|
|
|
|
c0 := xreadInitial()
|
|
ss, err := scram.NewServer(h, c0)
|
|
xcheckf(err, "starting scram")
|
|
c.log.Debug("scram auth", mlog.Field("authentication", ss.Authentication))
|
|
acc, _, err := store.OpenEmail(ss.Authentication)
|
|
if err != nil {
|
|
// todo: we could continue scram with a generated salt, deterministically generated
|
|
// from the username. that way we don't have to store anything but attackers cannot
|
|
// learn if an account exists. same for absent scram saltedpassword below.
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", ss.Authentication), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C454TempAuthFail, smtp.SeSys3Other0, "scram not possible")
|
|
}
|
|
defer func() {
|
|
if acc != nil {
|
|
err := acc.Close()
|
|
c.log.Check(err, "closing account")
|
|
}
|
|
}()
|
|
if ss.Authorization != "" && ss.Authorization != ss.Authentication {
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "authentication with authorization for different user not supported")
|
|
}
|
|
var xscram store.SCRAM
|
|
acc.WithRLock(func() {
|
|
err := acc.DB.Read(context.TODO(), func(tx *bstore.Tx) error {
|
|
password, err := bstore.QueryTx[store.Password](tx).Get()
|
|
if authVariant == "scram-sha-1" {
|
|
xscram = password.SCRAMSHA1
|
|
} else {
|
|
xscram = password.SCRAMSHA256
|
|
}
|
|
if err == bstore.ErrAbsent || err == nil && (len(xscram.Salt) == 0 || xscram.Iterations == 0 || len(xscram.SaltedPassword) == 0) {
|
|
c.log.Info("scram auth attempt without derived secrets set, save password again to store secrets", mlog.Field("address", ss.Authentication))
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", ss.Authentication), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C454TempAuthFail, smtp.SeSys3Other0, "scram not possible")
|
|
}
|
|
xcheckf(err, "fetching credentials")
|
|
return err
|
|
})
|
|
xcheckf(err, "read tx")
|
|
})
|
|
s1, err := ss.ServerFirst(xscram.Iterations, xscram.Salt)
|
|
xcheckf(err, "scram first server step")
|
|
c.writelinef("%d %s", smtp.C334ContinueAuth, base64.StdEncoding.EncodeToString([]byte(s1))) // ../rfc/4954:187
|
|
c2 := xreadContinuation()
|
|
s3, err := ss.Finish(c2, xscram.SaltedPassword)
|
|
if len(s3) > 0 {
|
|
c.writelinef("%d %s", smtp.C334ContinueAuth, base64.StdEncoding.EncodeToString([]byte(s3))) // ../rfc/4954:187
|
|
}
|
|
if err != nil {
|
|
c.readline() // Should be "*" for cancellation.
|
|
if errors.Is(err, scram.ErrInvalidProof) {
|
|
authResult = "badcreds"
|
|
c.log.Info("failed authentication attempt", mlog.Field("username", ss.Authentication), mlog.Field("remote", c.remoteIP))
|
|
xsmtpUserErrorf(smtp.C535AuthBadCreds, smtp.SePol7AuthBadCreds8, "bad credentials")
|
|
}
|
|
xcheckf(err, "server final")
|
|
}
|
|
|
|
// Client must still respond, but there is nothing to say. See ../rfc/9051:6221
|
|
// The message should be empty. todo: should we require it is empty?
|
|
xreadContinuation()
|
|
|
|
authResult = "ok"
|
|
c.authFailed = 0
|
|
c.setSlow(false)
|
|
c.account = acc
|
|
acc = nil // Cancel cleanup.
|
|
c.username = ss.Authentication
|
|
// ../rfc/4954:276
|
|
c.writecodeline(smtp.C235AuthSuccess, smtp.SePol7Other0, "nice", nil)
|
|
|
|
default:
|
|
// ../rfc/4954:176
|
|
xsmtpUserErrorf(smtp.C504ParamNotImpl, smtp.SeProto5BadParams4, "mechanism %s not supported", mech)
|
|
}
|
|
}
|
|
|
|
// ../rfc/5321:1879 ../rfc/5321:1025
|
|
func (c *conn) cmdMail(p *parser) {
|
|
// requirements for maximum line length:
|
|
// ../rfc/5321:3500 (base max of 512 including crlf) ../rfc/4954:134 (+500) ../rfc/1870:92 (+26) ../rfc/6152:90 (none specified) ../rfc/6531:231 (+10)
|
|
// todo future: enforce?
|
|
|
|
if c.transactionBad > 10 && c.transactionGood == 0 {
|
|
// If we get many bad transactions, it's probably a spammer that is guessing user names.
|
|
// Useful in combination with rate limiting.
|
|
// ../rfc/5321:4349
|
|
c.writecodeline(smtp.C550MailboxUnavail, smtp.SeAddr1Other0, "too many failures", nil)
|
|
panic(errIO)
|
|
}
|
|
|
|
c.xneedHello()
|
|
c.xcheckAuth()
|
|
if c.mailFrom != nil {
|
|
// ../rfc/5321:2507, though ../rfc/5321:1029 contradicts, implying a MAIL would also reset, but ../rfc/5321:1160 decides.
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "already have MAIL")
|
|
}
|
|
// Ensure clear transaction state on failure.
|
|
defer func() {
|
|
x := recover()
|
|
if x != nil {
|
|
// ../rfc/5321:2514
|
|
c.rset()
|
|
panic(x)
|
|
}
|
|
}()
|
|
p.xtake(" FROM:")
|
|
// note: no space after colon. ../rfc/5321:1093
|
|
// Allow illegal space for submission only, not for regular SMTP. Microsoft Outlook
|
|
// 365 Apps for Enterprise sends it.
|
|
if c.submission && !moxvar.Pedantic {
|
|
p.space()
|
|
}
|
|
rawRevPath := p.xrawReversePath()
|
|
paramSeen := map[string]bool{}
|
|
for p.space() {
|
|
// ../rfc/5321:2273
|
|
key := p.xparamKeyword()
|
|
|
|
K := strings.ToUpper(key)
|
|
if paramSeen[K] {
|
|
// e.g. ../rfc/6152:128
|
|
xsmtpUserErrorf(smtp.C501BadParamSyntax, smtp.SeProto5BadParams4, "duplicate param %q", key)
|
|
}
|
|
paramSeen[K] = true
|
|
|
|
switch K {
|
|
case "SIZE":
|
|
p.xtake("=")
|
|
size := p.xnumber(20) // ../rfc/1870:90
|
|
if size > c.maxMessageSize {
|
|
// ../rfc/1870:136 ../rfc/3463:382
|
|
ecode := smtp.SeSys3MsgLimitExceeded4
|
|
if size < config.DefaultMaxMsgSize {
|
|
ecode = smtp.SeMailbox2MsgLimitExceeded3
|
|
}
|
|
xsmtpUserErrorf(smtp.C552MailboxFull, ecode, "message too large")
|
|
}
|
|
// We won't verify the message is exactly the size the remote claims. Buf if it is
|
|
// larger, we'll abort the transaction when remote crosses the boundary.
|
|
case "BODY":
|
|
p.xtake("=")
|
|
// ../rfc/6152:90
|
|
v := p.xparamValue()
|
|
switch strings.ToUpper(v) {
|
|
case "7BIT":
|
|
c.has8bitmime = false
|
|
case "8BITMIME":
|
|
c.has8bitmime = true
|
|
default:
|
|
xsmtpUserErrorf(smtp.C555UnrecognizedAddrParams, smtp.SeProto5BadParams4, "unrecognized parameter %q", key)
|
|
}
|
|
case "AUTH":
|
|
// ../rfc/4954:455
|
|
|
|
// We act as if we don't trust the client to specify a mailbox. Instead, we always
|
|
// check the rfc5321.mailfrom and rfc5322.from before accepting the submission.
|
|
// ../rfc/4954:538
|
|
|
|
// ../rfc/4954:704
|
|
// todo future: should we accept utf-8-addr-xtext if there is no smtputf8, and utf-8 if there is? need to find a spec ../rfc/6533:259
|
|
p.xtake("=")
|
|
p.xtake("<")
|
|
p.xtext()
|
|
p.xtake(">")
|
|
case "SMTPUTF8":
|
|
// ../rfc/6531:213
|
|
c.smtputf8 = true
|
|
case "REQUIRETLS":
|
|
// ../rfc/8689:155
|
|
if !c.tls {
|
|
xsmtpUserErrorf(smtp.C530SecurityRequired, smtp.SePol7EncNeeded10, "requiretls only allowed on tls-encrypted connections")
|
|
} else if !c.extRequireTLS {
|
|
xsmtpUserErrorf(smtp.C555UnrecognizedAddrParams, smtp.SeSys3NotSupported3, "REQUIRETLS not allowed for this connection")
|
|
}
|
|
v := true
|
|
c.requireTLS = &v
|
|
default:
|
|
// ../rfc/5321:2230
|
|
xsmtpUserErrorf(smtp.C555UnrecognizedAddrParams, smtp.SeSys3NotSupported3, "unrecognized parameter %q", key)
|
|
}
|
|
}
|
|
|
|
// We now know if we have to parse the address with support for utf8.
|
|
pp := newParser(rawRevPath, c.smtputf8, c)
|
|
rpath := pp.xbareReversePath()
|
|
pp.xempty()
|
|
pp = nil
|
|
p.xend()
|
|
|
|
// For submission, check if reverse path is allowed. I.e. authenticated account
|
|
// must have the rpath configured. We do a check again on rfc5322.from during DATA.
|
|
rpathAllowed := func() bool {
|
|
// ../rfc/6409:349
|
|
if rpath.IsZero() {
|
|
return true
|
|
}
|
|
accName, _, _, err := mox.FindAccount(rpath.Localpart, rpath.IPDomain.Domain, false)
|
|
return err == nil && accName == c.account.Name
|
|
}
|
|
|
|
if !c.submission && !rpath.IPDomain.Domain.IsZero() {
|
|
// If rpath domain has null MX record or is otherwise not accepting email, reject.
|
|
// ../rfc/7505:181
|
|
// ../rfc/5321:4045
|
|
cidctx := context.WithValue(mox.Context, mlog.CidKey, c.cid)
|
|
ctx, cancel := context.WithTimeout(cidctx, time.Minute)
|
|
valid, err := checkMXRecords(ctx, c.resolver, rpath.IPDomain.Domain)
|
|
cancel()
|
|
if err != nil {
|
|
c.log.Infox("temporary reject for temporary mx lookup error", err)
|
|
xsmtpServerErrorf(codes{smtp.C451LocalErr, smtp.SeNet4Other0}, "cannot verify mx records for mailfrom domain")
|
|
} else if !valid {
|
|
c.log.Info("permanent reject because mailfrom domain does not accept mail")
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SePol7SenderHasNullMX27, "mailfrom domain not configured for mail")
|
|
}
|
|
}
|
|
|
|
if c.submission && (len(rpath.IPDomain.IP) > 0 || !rpathAllowed()) {
|
|
// ../rfc/6409:522
|
|
c.log.Info("submission with unconfigured mailfrom", mlog.Field("user", c.username), mlog.Field("mailfrom", rpath.String()))
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SePol7DeliveryUnauth1, "must match authenticated user")
|
|
} else if !c.submission && len(rpath.IPDomain.IP) > 0 {
|
|
// todo future: allow if the IP is the same as this connection is coming from? does later code allow this?
|
|
c.log.Info("delivery from address without domain", mlog.Field("mailfrom", rpath.String()))
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SePol7Other0, "domain name required")
|
|
}
|
|
|
|
if Localserve && strings.HasPrefix(string(rpath.Localpart), "mailfrom") {
|
|
c.xlocalserveError(rpath.Localpart)
|
|
}
|
|
|
|
c.mailFrom = &rpath
|
|
|
|
c.bwritecodeline(smtp.C250Completed, smtp.SeAddr1Other0, "looking good", nil)
|
|
}
|
|
|
|
// ../rfc/5321:1916 ../rfc/5321:1054
|
|
func (c *conn) cmdRcpt(p *parser) {
|
|
c.xneedHello()
|
|
c.xcheckAuth()
|
|
if c.mailFrom == nil {
|
|
// ../rfc/5321:1088
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "missing MAIL FROM")
|
|
}
|
|
|
|
// ../rfc/5321:1985
|
|
p.xtake(" TO:")
|
|
// note: no space after colon. ../rfc/5321:1093
|
|
// Allow illegal space for submission only, not for regular SMTP. Microsoft Outlook
|
|
// 365 Apps for Enterprise sends it.
|
|
if c.submission && !moxvar.Pedantic {
|
|
p.space()
|
|
}
|
|
var fpath smtp.Path
|
|
if p.take("<POSTMASTER>") {
|
|
fpath = smtp.Path{Localpart: "postmaster"}
|
|
} else {
|
|
fpath = p.xforwardPath()
|
|
}
|
|
for p.space() {
|
|
// ../rfc/5321:2275
|
|
key := p.xparamKeyword()
|
|
// K := strings.ToUpper(key)
|
|
// todo future: DSN, ../rfc/3461, with "NOTIFY"
|
|
// ../rfc/5321:2230
|
|
xsmtpUserErrorf(smtp.C555UnrecognizedAddrParams, smtp.SeSys3NotSupported3, "unrecognized parameter %q", key)
|
|
}
|
|
p.xend()
|
|
|
|
// Check if TLS is enabled if required. It's not great that sender/recipient
|
|
// addresses may have been exposed in plaintext before we can reject delivery. The
|
|
// recipient could be the tls reporting addresses, which must always be able to
|
|
// receive in plain text.
|
|
c.xneedTLSForDelivery(fpath)
|
|
|
|
// todo future: for submission, should we do explicit verification that domains are fully qualified? also for mail from. ../rfc/6409:420
|
|
|
|
if len(c.recipients) >= 100 {
|
|
// ../rfc/5321:3535 ../rfc/5321:3571
|
|
xsmtpUserErrorf(smtp.C452StorageFull, smtp.SeProto5TooManyRcpts3, "max of 100 recipients reached")
|
|
}
|
|
|
|
// We don't want to allow delivery to multiple recipients with a null reverse path.
|
|
// Why would anyone send like that? Null reverse path is intended for delivery
|
|
// notifications, they should go to a single recipient.
|
|
if !c.submission && len(c.recipients) > 0 && c.mailFrom.IsZero() {
|
|
xsmtpUserErrorf(smtp.C452StorageFull, smtp.SeProto5TooManyRcpts3, "only one recipient allowed with null reverse address")
|
|
}
|
|
|
|
// Do not accept multiple recipients if remote does not pass SPF. Because we don't
|
|
// want to generate DSNs to unverified domains. This is the moment we
|
|
// can refuse individual recipients, DATA will be too late. Because mail
|
|
// servers must handle a max recipient limit gracefully and still send to the
|
|
// recipients that are accepted, this should not cause problems. Though we are in
|
|
// violation because the limit must be >= 100.
|
|
// ../rfc/5321:3598
|
|
// ../rfc/5321:4045
|
|
// Also see ../rfc/7489:2214
|
|
if !c.submission && len(c.recipients) == 1 && !Localserve {
|
|
// note: because of check above, mailFrom cannot be the null address.
|
|
var pass bool
|
|
d := c.mailFrom.IPDomain.Domain
|
|
if !d.IsZero() {
|
|
// todo: use this spf result for DATA.
|
|
spfArgs := spf.Args{
|
|
RemoteIP: c.remoteIP,
|
|
MailFromLocalpart: c.mailFrom.Localpart,
|
|
MailFromDomain: d,
|
|
HelloDomain: c.hello,
|
|
LocalIP: c.localIP,
|
|
LocalHostname: c.hostname,
|
|
}
|
|
cidctx := context.WithValue(mox.Context, mlog.CidKey, c.cid)
|
|
spfctx, spfcancel := context.WithTimeout(cidctx, time.Minute)
|
|
defer spfcancel()
|
|
receivedSPF, _, _, _, err := spf.Verify(spfctx, c.resolver, spfArgs)
|
|
spfcancel()
|
|
if err != nil {
|
|
c.log.Errorx("spf verify for multiple recipients", err)
|
|
}
|
|
pass = receivedSPF.Identity == spf.ReceivedMailFrom && receivedSPF.Result == spf.StatusPass
|
|
}
|
|
if !pass {
|
|
xsmtpUserErrorf(smtp.C452StorageFull, smtp.SeProto5TooManyRcpts3, "only one recipient allowed without spf pass")
|
|
}
|
|
}
|
|
|
|
if Localserve {
|
|
if strings.HasPrefix(string(fpath.Localpart), "rcptto") {
|
|
c.xlocalserveError(fpath.Localpart)
|
|
}
|
|
|
|
// If account or destination doesn't exist, it will be handled during delivery. For
|
|
// submissions, which is the common case, we'll deliver to the logged in user,
|
|
// which is typically the mox user.
|
|
acc, _ := mox.Conf.Account("mox")
|
|
dest := acc.Destinations["mox@localhost"]
|
|
c.recipients = append(c.recipients, rcptAccount{fpath, true, "mox", dest, "mox@localhost"})
|
|
} else if len(fpath.IPDomain.IP) > 0 {
|
|
if !c.submission {
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, "not accepting email for ip")
|
|
}
|
|
c.recipients = append(c.recipients, rcptAccount{fpath, false, "", config.Destination{}, ""})
|
|
} else if accountName, canonical, addr, err := mox.FindAccount(fpath.Localpart, fpath.IPDomain.Domain, true); err == nil {
|
|
// note: a bare postmaster, without domain, is handled by FindAccount. ../rfc/5321:735
|
|
c.recipients = append(c.recipients, rcptAccount{fpath, true, accountName, addr, canonical})
|
|
} else if errors.Is(err, mox.ErrDomainNotFound) {
|
|
if !c.submission {
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, "not accepting email for domain")
|
|
}
|
|
// We'll be delivering this email.
|
|
c.recipients = append(c.recipients, rcptAccount{fpath, false, "", config.Destination{}, ""})
|
|
} else if errors.Is(err, mox.ErrAccountNotFound) {
|
|
if c.submission {
|
|
// For submission, we're transparent about which user exists. Should be fine for the typical small-scale deploy.
|
|
// ../rfc/5321:1071
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, "no such user")
|
|
}
|
|
// We pretend to accept. We don't want to let remote know the user does not exist
|
|
// until after DATA. Because then remote has committed to sending a message.
|
|
// note: not local for !c.submission is the signal this address is in error.
|
|
c.recipients = append(c.recipients, rcptAccount{fpath, false, "", config.Destination{}, ""})
|
|
} else {
|
|
c.log.Errorx("looking up account for delivery", err, mlog.Field("rcptto", fpath))
|
|
xsmtpServerErrorf(codes{smtp.C451LocalErr, smtp.SeSys3Other0}, "error processing")
|
|
}
|
|
c.bwritecodeline(smtp.C250Completed, smtp.SeAddr1Other0, "now on the list", nil)
|
|
}
|
|
|
|
// ../rfc/5321:1992 ../rfc/5321:1098
|
|
func (c *conn) cmdData(p *parser) {
|
|
c.xneedHello()
|
|
c.xcheckAuth()
|
|
if c.mailFrom == nil {
|
|
// ../rfc/5321:1130
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "missing MAIL FROM")
|
|
}
|
|
if len(c.recipients) == 0 {
|
|
// ../rfc/5321:1130
|
|
xsmtpUserErrorf(smtp.C503BadCmdSeq, smtp.SeProto5BadCmdOrSeq1, "missing RCPT TO")
|
|
}
|
|
|
|
// ../rfc/5321:2066
|
|
p.xend()
|
|
|
|
// todo future: we could start a reader for a single line. we would then create a context that would be canceled on i/o errors.
|
|
|
|
// Entire delivery should be done within 30 minutes, or we abort.
|
|
cidctx := context.WithValue(mox.Context, mlog.CidKey, c.cid)
|
|
cmdctx, cmdcancel := context.WithTimeout(cidctx, 30*time.Minute)
|
|
defer cmdcancel()
|
|
// Deadline is taken into account by Read and Write.
|
|
c.deadline, _ = cmdctx.Deadline()
|
|
defer func() {
|
|
c.deadline = time.Time{}
|
|
}()
|
|
|
|
// ../rfc/5321:1994
|
|
c.writelinef("354 see you at the bare dot")
|
|
|
|
// Mark as tracedata.
|
|
defer c.xtrace(mlog.LevelTracedata)()
|
|
|
|
// We read the data into a temporary file. We limit the size and do basic analysis while reading.
|
|
dataFile, err := store.CreateMessageTemp("smtp-deliver")
|
|
if err != nil {
|
|
xsmtpServerErrorf(errCodes(smtp.C451LocalErr, smtp.SeSys3Other0, err), "creating temporary file for message: %s", err)
|
|
}
|
|
defer store.CloseRemoveTempFile(c.log, dataFile, "smtpserver delivered message")
|
|
msgWriter := message.NewWriter(dataFile)
|
|
dr := smtp.NewDataReader(c.r)
|
|
n, err := io.Copy(&limitWriter{maxSize: c.maxMessageSize, w: msgWriter}, dr)
|
|
c.xtrace(mlog.LevelTrace) // Restore.
|
|
if err != nil {
|
|
if errors.Is(err, errMessageTooLarge) {
|
|
// ../rfc/1870:136 and ../rfc/3463:382
|
|
ecode := smtp.SeSys3MsgLimitExceeded4
|
|
if n < config.DefaultMaxMsgSize {
|
|
ecode = smtp.SeMailbox2MsgLimitExceeded3
|
|
}
|
|
c.writecodeline(smtp.C451LocalErr, ecode, fmt.Sprintf("error copying data to file (%s)", mox.ReceivedID(c.cid)), err)
|
|
panic(fmt.Errorf("remote sent too much DATA: %w", errIO))
|
|
}
|
|
|
|
// Something is failing on our side. We want to let remote know. So write an error response,
|
|
// then discard the remaining data so the remote client is more likely to see our
|
|
// response. Our write is synchronous, there is a risk no window/buffer space is
|
|
// available and our write blocks us from reading remaining data, leading to
|
|
// deadlock. We have a timeout on our connection writes though, so worst case we'll
|
|
// abort the connection due to expiration.
|
|
c.writecodeline(smtp.C451LocalErr, smtp.SeSys3Other0, fmt.Sprintf("error copying data to file (%s)", mox.ReceivedID(c.cid)), err)
|
|
io.Copy(io.Discard, dr)
|
|
return
|
|
}
|
|
|
|
// Basic sanity checks on messages before we send them out to the world. Just
|
|
// trying to be strict in what we do to others and liberal in what we accept.
|
|
if c.submission {
|
|
if !msgWriter.HaveBody {
|
|
// ../rfc/6409:541
|
|
xsmtpUserErrorf(smtp.C554TransactionFailed, smtp.SeMsg6Other0, "message requires both header and body section")
|
|
}
|
|
// Check only for pedantic mode because ios mail will attempt to send smtputf8 with
|
|
// non-ascii in message from localpart without using 8bitmime.
|
|
if moxvar.Pedantic && msgWriter.Has8bit && !c.has8bitmime {
|
|
// ../rfc/5321:906
|
|
xsmtpUserErrorf(smtp.C500BadSyntax, smtp.SeMsg6Other0, "message with non-us-ascii requires 8bitmime extension")
|
|
}
|
|
}
|
|
|
|
if Localserve && moxvar.Pedantic {
|
|
// Require that message can be parsed fully.
|
|
p, err := message.Parse(c.log, false, dataFile)
|
|
if err == nil {
|
|
err = p.Walk(c.log, nil)
|
|
}
|
|
if err != nil {
|
|
// ../rfc/6409:541
|
|
xsmtpUserErrorf(smtp.C554TransactionFailed, smtp.SeMsg6Other0, "malformed message: %v", err)
|
|
}
|
|
}
|
|
|
|
// Prepare "Received" header.
|
|
// ../rfc/5321:2051 ../rfc/5321:3302
|
|
// ../rfc/5321:3311 ../rfc/6531:578
|
|
var recvFrom string
|
|
var iprevStatus iprev.Status // Only for delivery, not submission.
|
|
var iprevAuthentic bool
|
|
if c.submission {
|
|
// Hide internal hosts.
|
|
// todo future: make this a config option, where admins specify ip ranges that they don't want exposed. also see ../rfc/5321:4321
|
|
recvFrom = message.HeaderCommentDomain(mox.Conf.Static.HostnameDomain, c.smtputf8)
|
|
} else {
|
|
if len(c.hello.IP) > 0 {
|
|
recvFrom = smtp.AddressLiteral(c.hello.IP)
|
|
} else {
|
|
// ASCII-only version added after the extended-domain syntax below, because the
|
|
// comment belongs to "BY" which comes immediately after "FROM".
|
|
recvFrom = c.hello.Domain.XName(c.smtputf8)
|
|
}
|
|
iprevctx, iprevcancel := context.WithTimeout(cmdctx, time.Minute)
|
|
var revName string
|
|
var revNames []string
|
|
iprevStatus, revName, revNames, iprevAuthentic, err = iprev.Lookup(iprevctx, c.resolver, c.remoteIP)
|
|
iprevcancel()
|
|
if err != nil {
|
|
c.log.Infox("reverse-forward lookup", err, mlog.Field("remoteip", c.remoteIP))
|
|
}
|
|
c.log.Debug("dns iprev check", mlog.Field("addr", c.remoteIP), mlog.Field("status", iprevStatus))
|
|
var name string
|
|
if revName != "" {
|
|
name = revName
|
|
} else if len(revNames) > 0 {
|
|
name = revNames[0]
|
|
}
|
|
name = strings.TrimSuffix(name, ".")
|
|
recvFrom += " ("
|
|
if name != "" && name != c.hello.Domain.XName(c.smtputf8) {
|
|
recvFrom += name + " "
|
|
}
|
|
recvFrom += smtp.AddressLiteral(c.remoteIP) + ")"
|
|
if c.smtputf8 && c.hello.Domain.Unicode != "" {
|
|
recvFrom += " (" + c.hello.Domain.ASCII + ")"
|
|
}
|
|
}
|
|
recvBy := mox.Conf.Static.HostnameDomain.XName(c.smtputf8)
|
|
recvBy += " (" + smtp.AddressLiteral(c.localIP) + ")" // todo: hide ip if internal?
|
|
if c.smtputf8 && mox.Conf.Static.HostnameDomain.Unicode != "" {
|
|
// This syntax is part of "VIA".
|
|
recvBy += " (" + mox.Conf.Static.HostnameDomain.ASCII + ")"
|
|
}
|
|
|
|
// ../rfc/3848:34 ../rfc/6531:791
|
|
with := "SMTP"
|
|
if c.smtputf8 {
|
|
with = "UTF8SMTP"
|
|
} else if c.ehlo {
|
|
with = "ESMTP"
|
|
}
|
|
if c.tls {
|
|
with += "S"
|
|
}
|
|
if c.account != nil {
|
|
// ../rfc/4954:660
|
|
with += "A"
|
|
}
|
|
|
|
// Assume transaction does not succeed. If it does, we'll compensate.
|
|
c.transactionBad++
|
|
|
|
recvHdrFor := func(rcptTo string) string {
|
|
recvHdr := &message.HeaderWriter{}
|
|
// For additional Received-header clauses, see:
|
|
// https://www.iana.org/assignments/mail-parameters/mail-parameters.xhtml#table-mail-parameters-8
|
|
withComment := ""
|
|
if c.requireTLS != nil && *c.requireTLS {
|
|
// Comment is actually part of ID ABNF rule. ../rfc/5321:3336
|
|
withComment = " (requiretls)"
|
|
}
|
|
recvHdr.Add(" ", "Received:", "from", recvFrom, "by", recvBy, "via", "tcp", "with", with+withComment, "id", mox.ReceivedID(c.cid)) // ../rfc/5321:3158
|
|
if c.tls {
|
|
tlsConn := c.conn.(*tls.Conn)
|
|
tlsComment := message.TLSReceivedComment(c.log, tlsConn.ConnectionState())
|
|
recvHdr.Add(" ", tlsComment...)
|
|
}
|
|
recvHdr.Add(" ", "for", "<"+rcptTo+">;", time.Now().Format(message.RFC5322Z))
|
|
return recvHdr.String()
|
|
}
|
|
|
|
// Submission is easiest because user is trusted. Far fewer checks to make. So
|
|
// handle it first, and leave the rest of the function for handling wild west
|
|
// internet traffic.
|
|
if c.submission {
|
|
c.submit(cmdctx, recvHdrFor, msgWriter, dataFile)
|
|
} else {
|
|
c.deliver(cmdctx, recvHdrFor, msgWriter, iprevStatus, iprevAuthentic, dataFile)
|
|
}
|
|
}
|
|
|
|
// Check if a message has unambiguous "TLS-Required: No" header. Messages must not
|
|
// contain multiple TLS-Required headers. The only valid value is "no". But we'll
|
|
// accept multiple headers as long as all they are all "no".
|
|
// ../rfc/8689:223
|
|
func hasTLSRequiredNo(h textproto.MIMEHeader) bool {
|
|
l := h.Values("Tls-Required")
|
|
if len(l) == 0 {
|
|
return false
|
|
}
|
|
for _, v := range l {
|
|
if !strings.EqualFold(v, "no") {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// submit is used for mail from authenticated users that we will try to deliver.
|
|
func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWriter *message.Writer, dataFile *os.File) {
|
|
// Similar between ../smtpserver/server.go:/submit\( and ../webmail/webmail.go:/MessageSubmit\(
|
|
|
|
var msgPrefix []byte
|
|
|
|
// Check that user is only sending email as one of its configured identities. Not
|
|
// for other users.
|
|
// We don't check the Sender field, there is no expectation of verification, ../rfc/7489:2948
|
|
// and with Resent headers it seems valid to have someone else as Sender. ../rfc/5322:1578
|
|
msgFrom, header, err := message.From(c.log, true, dataFile)
|
|
if err != nil {
|
|
metricSubmission.WithLabelValues("badmessage").Inc()
|
|
c.log.Infox("parsing message From address", err, mlog.Field("user", c.username))
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeMsg6Other0, "cannot parse header or From address: %v", err)
|
|
}
|
|
accName, _, _, err := mox.FindAccount(msgFrom.Localpart, msgFrom.Domain, true)
|
|
if err != nil || accName != c.account.Name {
|
|
// ../rfc/6409:522
|
|
if err == nil {
|
|
err = mox.ErrAccountNotFound
|
|
}
|
|
metricSubmission.WithLabelValues("badfrom").Inc()
|
|
c.log.Infox("verifying message From address", err, mlog.Field("user", c.username), mlog.Field("msgfrom", msgFrom))
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SePol7DeliveryUnauth1, "must match authenticated user")
|
|
}
|
|
|
|
// TLS-Required: No header makes us not enforce recipient domain's TLS policy.
|
|
// ../rfc/8689:206
|
|
// Only when requiretls smtp extension wasn't used. ../rfc/8689:246
|
|
if c.requireTLS == nil && hasTLSRequiredNo(header) {
|
|
v := false
|
|
c.requireTLS = &v
|
|
}
|
|
|
|
// Outgoing messages should not have a Return-Path header. The final receiving mail
|
|
// server will add it.
|
|
// ../rfc/5321:3233
|
|
if header.Values("Return-Path") != nil {
|
|
metricSubmission.WithLabelValues("badheader").Inc()
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeMsg6Other0, "message must not have Return-Path header")
|
|
}
|
|
|
|
// Add Message-Id header if missing.
|
|
// ../rfc/5321:4131 ../rfc/6409:751
|
|
messageID := header.Get("Message-Id")
|
|
if messageID == "" {
|
|
messageID = mox.MessageIDGen(c.smtputf8)
|
|
msgPrefix = append(msgPrefix, fmt.Sprintf("Message-Id: <%s>\r\n", messageID)...)
|
|
}
|
|
|
|
// ../rfc/6409:745
|
|
if header.Get("Date") == "" {
|
|
msgPrefix = append(msgPrefix, "Date: "+time.Now().Format(message.RFC5322Z)+"\r\n"...)
|
|
}
|
|
|
|
// Check outoging message rate limit.
|
|
err = c.account.DB.Read(ctx, func(tx *bstore.Tx) error {
|
|
rcpts := make([]smtp.Path, len(c.recipients))
|
|
for i, r := range c.recipients {
|
|
rcpts[i] = r.rcptTo
|
|
}
|
|
msglimit, rcptlimit, err := c.account.SendLimitReached(tx, rcpts)
|
|
xcheckf(err, "checking sender limit")
|
|
if msglimit >= 0 {
|
|
metricSubmission.WithLabelValues("messagelimiterror").Inc()
|
|
xsmtpUserErrorf(smtp.C451LocalErr, smtp.SePol7DeliveryUnauth1, "max number of messages (%d) over past 24h reached, try increasing per-account setting MaxOutgoingMessagesPerDay", msglimit)
|
|
} else if rcptlimit >= 0 {
|
|
metricSubmission.WithLabelValues("recipientlimiterror").Inc()
|
|
xsmtpUserErrorf(smtp.C451LocalErr, smtp.SePol7DeliveryUnauth1, "max number of new/first-time recipients (%d) over past 24h reached, try increasing per-account setting MaxFirstTimeRecipientsPerDay", rcptlimit)
|
|
}
|
|
return nil
|
|
})
|
|
xcheckf(err, "read-only transaction")
|
|
|
|
// todo future: in a pedantic mode, we can parse the headers, and return an error if rcpt is only in To or Cc header, and not in the non-empty Bcc header. indicates a client that doesn't blind those bcc's.
|
|
|
|
// Add DKIM signatures.
|
|
confDom, ok := mox.Conf.Domain(msgFrom.Domain)
|
|
if !ok {
|
|
c.log.Error("domain disappeared", mlog.Field("domain", msgFrom.Domain))
|
|
xsmtpServerErrorf(codes{smtp.C451LocalErr, smtp.SeSys3Other0}, "internal error")
|
|
}
|
|
|
|
dkimConfig := confDom.DKIM
|
|
if len(dkimConfig.Sign) > 0 {
|
|
if canonical, err := mox.CanonicalLocalpart(msgFrom.Localpart, confDom); err != nil {
|
|
c.log.Errorx("determining canonical localpart for dkim signing", err, mlog.Field("localpart", msgFrom.Localpart))
|
|
} else if dkimHeaders, err := dkim.Sign(ctx, canonical, msgFrom.Domain, dkimConfig, c.smtputf8, store.FileMsgReader(msgPrefix, dataFile)); err != nil {
|
|
c.log.Errorx("dkim sign for domain", err, mlog.Field("domain", msgFrom.Domain))
|
|
metricServerErrors.WithLabelValues("dkimsign").Inc()
|
|
} else {
|
|
msgPrefix = append(msgPrefix, []byte(dkimHeaders)...)
|
|
}
|
|
}
|
|
|
|
authResults := message.AuthResults{
|
|
Hostname: mox.Conf.Static.HostnameDomain.XName(c.smtputf8),
|
|
Comment: mox.Conf.Static.HostnameDomain.ASCIIExtra(c.smtputf8),
|
|
Methods: []message.AuthMethod{
|
|
{
|
|
Method: "auth",
|
|
Result: "pass",
|
|
Props: []message.AuthProp{
|
|
message.MakeAuthProp("smtp", "mailfrom", c.mailFrom.XString(c.smtputf8), true, c.mailFrom.ASCIIExtra(c.smtputf8)),
|
|
},
|
|
},
|
|
},
|
|
}
|
|
msgPrefix = append(msgPrefix, []byte(authResults.Header())...)
|
|
|
|
// We always deliver through the queue. It would be more efficient to deliver
|
|
// directly, but we don't want to circumvent all the anti-spam measures. Accounts
|
|
// on a single mox instance should be allowed to block each other.
|
|
for _, rcptAcc := range c.recipients {
|
|
if Localserve {
|
|
code, timeout := localserveNeedsError(rcptAcc.rcptTo.Localpart)
|
|
if timeout {
|
|
c.log.Info("timing out submission due to special localpart")
|
|
mox.Sleep(mox.Context, time.Hour)
|
|
xsmtpServerErrorf(codes{smtp.C451LocalErr, smtp.SeSys3Other0}, "timing out submission due to special localpart")
|
|
} else if code != 0 {
|
|
c.log.Info("failure due to special localpart", mlog.Field("code", code))
|
|
xsmtpServerErrorf(codes{code, smtp.SeOther00}, "failure with code %d due to special localpart", code)
|
|
}
|
|
}
|
|
|
|
xmsgPrefix := append([]byte(recvHdrFor(rcptAcc.rcptTo.String())), msgPrefix...)
|
|
|
|
msgSize := int64(len(xmsgPrefix)) + msgWriter.Size
|
|
qm := queue.MakeMsg(c.account.Name, *c.mailFrom, rcptAcc.rcptTo, msgWriter.Has8bit, c.smtputf8, msgSize, messageID, xmsgPrefix, c.requireTLS)
|
|
if err := queue.Add(ctx, c.log, &qm, dataFile); err != nil {
|
|
// Aborting the transaction is not great. But continuing and generating DSNs will
|
|
// probably result in errors as well...
|
|
metricSubmission.WithLabelValues("queueerror").Inc()
|
|
c.log.Errorx("queuing message", err)
|
|
xsmtpServerErrorf(errCodes(smtp.C451LocalErr, smtp.SeSys3Other0, err), "error delivering message: %v", err)
|
|
}
|
|
metricSubmission.WithLabelValues("ok").Inc()
|
|
c.log.Info("message queued for delivery", mlog.Field("mailfrom", *c.mailFrom), mlog.Field("rcptto", rcptAcc.rcptTo), mlog.Field("smtputf8", c.smtputf8), mlog.Field("msgsize", msgSize))
|
|
|
|
err := c.account.DB.Insert(ctx, &store.Outgoing{Recipient: rcptAcc.rcptTo.XString(true)})
|
|
xcheckf(err, "adding outgoing message")
|
|
}
|
|
|
|
c.transactionGood++
|
|
c.transactionBad-- // Compensate for early earlier pessimistic increase.
|
|
|
|
c.rset()
|
|
c.writecodeline(smtp.C250Completed, smtp.SeMailbox2Other0, "it is done", nil)
|
|
}
|
|
|
|
func ipmasked(ip net.IP) (string, string, string) {
|
|
if ip.To4() != nil {
|
|
m1 := ip.String()
|
|
m2 := ip.Mask(net.CIDRMask(26, 32)).String()
|
|
m3 := ip.Mask(net.CIDRMask(21, 32)).String()
|
|
return m1, m2, m3
|
|
}
|
|
m1 := ip.Mask(net.CIDRMask(64, 128)).String()
|
|
m2 := ip.Mask(net.CIDRMask(48, 128)).String()
|
|
m3 := ip.Mask(net.CIDRMask(32, 128)).String()
|
|
return m1, m2, m3
|
|
}
|
|
|
|
func localserveNeedsError(lp smtp.Localpart) (code int, timeout bool) {
|
|
s := string(lp)
|
|
if strings.HasSuffix(s, "temperror") {
|
|
return smtp.C451LocalErr, false
|
|
} else if strings.HasSuffix(s, "permerror") {
|
|
return smtp.C550MailboxUnavail, false
|
|
} else if strings.HasSuffix(s, "timeout") {
|
|
return 0, true
|
|
}
|
|
if len(s) < 3 {
|
|
return 0, false
|
|
}
|
|
s = s[len(s)-3:]
|
|
v, err := strconv.ParseInt(s, 10, 32)
|
|
if err != nil {
|
|
return 0, false
|
|
}
|
|
if v < 400 || v > 600 {
|
|
return 0, false
|
|
}
|
|
return int(v), false
|
|
}
|
|
|
|
func (c *conn) xlocalserveError(lp smtp.Localpart) {
|
|
code, timeout := localserveNeedsError(lp)
|
|
if timeout {
|
|
c.log.Info("timing out due to special localpart")
|
|
mox.Sleep(mox.Context, time.Hour)
|
|
xsmtpServerErrorf(codes{smtp.C451LocalErr, smtp.SeSys3Other0}, "timing out command due to special localpart")
|
|
} else if code != 0 {
|
|
c.log.Info("failure due to special localpart", mlog.Field("code", code))
|
|
metricDelivery.WithLabelValues("delivererror", "localserve").Inc()
|
|
xsmtpServerErrorf(codes{code, smtp.SeOther00}, "failure with code %d due to special localpart", code)
|
|
}
|
|
}
|
|
|
|
// deliver is called for incoming messages from external, typically untrusted
|
|
// sources. i.e. not submitted by authenticated users.
|
|
func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgWriter *message.Writer, iprevStatus iprev.Status, iprevAuthentic bool, dataFile *os.File) {
|
|
// todo: in decision making process, if we run into (some) temporary errors, attempt to continue. if we decide to accept, all good. if we decide to reject, we'll make it a temporary reject.
|
|
|
|
msgFrom, headers, err := message.From(c.log, false, dataFile)
|
|
if err != nil {
|
|
c.log.Infox("parsing message for From address", err)
|
|
}
|
|
|
|
// Basic loop detection. ../rfc/5321:4065 ../rfc/5321:1526
|
|
if len(headers.Values("Received")) > 100 {
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeNet4Loop6, "loop detected, more than 100 Received headers")
|
|
}
|
|
|
|
// TLS-Required: No header makes us not enforce recipient domain's TLS policy.
|
|
// Since we only deliver locally at the moment, this won't influence our behaviour.
|
|
// Once we forward, it would our delivery attempts.
|
|
// ../rfc/8689:206
|
|
// Only when requiretls smtp extension wasn't used. ../rfc/8689:246
|
|
if c.requireTLS == nil && hasTLSRequiredNo(headers) {
|
|
v := false
|
|
c.requireTLS = &v
|
|
}
|
|
|
|
// We'll be building up an Authentication-Results header.
|
|
authResults := message.AuthResults{
|
|
Hostname: mox.Conf.Static.HostnameDomain.XName(c.smtputf8),
|
|
}
|
|
|
|
commentAuthentic := func(v bool) string {
|
|
if v {
|
|
return "with dnssec"
|
|
}
|
|
return "without dnssec"
|
|
}
|
|
|
|
// Reverse IP lookup results.
|
|
// todo future: how useful is this?
|
|
// ../rfc/5321:2481
|
|
authResults.Methods = append(authResults.Methods, message.AuthMethod{
|
|
Method: "iprev",
|
|
Result: string(iprevStatus),
|
|
Comment: commentAuthentic(iprevAuthentic),
|
|
Props: []message.AuthProp{
|
|
message.MakeAuthProp("policy", "iprev", c.remoteIP.String(), false, ""),
|
|
},
|
|
})
|
|
|
|
// SPF and DKIM verification in parallel.
|
|
var wg sync.WaitGroup
|
|
|
|
// DKIM
|
|
wg.Add(1)
|
|
var dkimResults []dkim.Result
|
|
var dkimErr error
|
|
go func() {
|
|
defer func() {
|
|
x := recover() // Should not happen, but don't take program down if it does.
|
|
if x != nil {
|
|
c.log.Error("dkim verify panic", mlog.Field("err", x))
|
|
debug.PrintStack()
|
|
metrics.PanicInc(metrics.Dkimverify)
|
|
}
|
|
}()
|
|
defer wg.Done()
|
|
// We always evaluate all signatures. We want to build up reputation for each
|
|
// domain in the signature.
|
|
const ignoreTestMode = false
|
|
// todo future: longer timeout? we have to read through the entire email, which can be large, possibly multiple times.
|
|
dkimctx, dkimcancel := context.WithTimeout(ctx, time.Minute)
|
|
defer dkimcancel()
|
|
// todo future: we could let user configure which dkim headers they require
|
|
dkimResults, dkimErr = dkim.Verify(dkimctx, c.resolver, c.smtputf8, dkim.DefaultPolicy, dataFile, ignoreTestMode)
|
|
dkimcancel()
|
|
}()
|
|
|
|
// SPF.
|
|
// ../rfc/7208:472
|
|
var receivedSPF spf.Received
|
|
var spfDomain dns.Domain
|
|
var spfExpl string
|
|
var spfAuthentic bool
|
|
var spfErr error
|
|
spfArgs := spf.Args{
|
|
RemoteIP: c.remoteIP,
|
|
MailFromLocalpart: c.mailFrom.Localpart,
|
|
MailFromDomain: c.mailFrom.IPDomain.Domain, // Can be empty.
|
|
HelloDomain: c.hello,
|
|
LocalIP: c.localIP,
|
|
LocalHostname: c.hostname,
|
|
}
|
|
wg.Add(1)
|
|
go func() {
|
|
defer func() {
|
|
x := recover() // Should not happen, but don't take program down if it does.
|
|
if x != nil {
|
|
c.log.Error("spf verify panic", mlog.Field("err", x))
|
|
debug.PrintStack()
|
|
metrics.PanicInc(metrics.Spfverify)
|
|
}
|
|
}()
|
|
defer wg.Done()
|
|
spfctx, spfcancel := context.WithTimeout(ctx, time.Minute)
|
|
defer spfcancel()
|
|
receivedSPF, spfDomain, spfExpl, spfAuthentic, spfErr = spf.Verify(spfctx, c.resolver, spfArgs)
|
|
spfcancel()
|
|
if spfErr != nil {
|
|
c.log.Infox("spf verify", spfErr)
|
|
}
|
|
}()
|
|
|
|
// Wait for DKIM and SPF validation to finish.
|
|
wg.Wait()
|
|
|
|
// Give immediate response if all recipients are unknown.
|
|
nunknown := 0
|
|
for _, r := range c.recipients {
|
|
if !r.local {
|
|
nunknown++
|
|
}
|
|
}
|
|
if nunknown == len(c.recipients) {
|
|
// During RCPT TO we found that the address does not exist.
|
|
c.log.Info("deliver attempt to unknown user(s)", mlog.Field("recipients", c.recipients))
|
|
|
|
// Crude attempt to slow down someone trying to guess names. Would work better
|
|
// with connection rate limiter.
|
|
if unknownRecipientsDelay > 0 {
|
|
mox.Sleep(ctx, unknownRecipientsDelay)
|
|
}
|
|
|
|
// todo future: if remote does not look like a properly configured mail system, respond with generic 451 error? to prevent any random internet system from discovering accounts. we could give proper response if spf for ehlo or mailfrom passes.
|
|
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, "no such user(s)")
|
|
}
|
|
|
|
// Add DKIM results to Authentication-Results header.
|
|
authResAddDKIM := func(result, comment, reason string, props []message.AuthProp) {
|
|
dm := message.AuthMethod{
|
|
Method: "dkim",
|
|
Result: result,
|
|
Comment: comment,
|
|
Reason: reason,
|
|
Props: props,
|
|
}
|
|
authResults.Methods = append(authResults.Methods, dm)
|
|
}
|
|
if dkimErr != nil {
|
|
c.log.Errorx("dkim verify", dkimErr)
|
|
authResAddDKIM("none", "", dkimErr.Error(), nil)
|
|
} else if len(dkimResults) == 0 {
|
|
c.log.Info("no dkim-signature header", mlog.Field("mailfrom", c.mailFrom))
|
|
authResAddDKIM("none", "", "no dkim signatures", nil)
|
|
}
|
|
for i, r := range dkimResults {
|
|
var domain, selector dns.Domain
|
|
var identity *dkim.Identity
|
|
var comment string
|
|
var props []message.AuthProp
|
|
if r.Sig != nil {
|
|
if r.Record != nil && r.Record.PublicKey != nil {
|
|
if pubkey, ok := r.Record.PublicKey.(*rsa.PublicKey); ok {
|
|
comment = fmt.Sprintf("%d bit rsa, ", pubkey.N.BitLen())
|
|
}
|
|
}
|
|
|
|
sig := base64.StdEncoding.EncodeToString(r.Sig.Signature)
|
|
sig = sig[:12] // Must be at least 8 characters and unique among the signatures.
|
|
props = []message.AuthProp{
|
|
message.MakeAuthProp("header", "d", r.Sig.Domain.XName(c.smtputf8), true, r.Sig.Domain.ASCIIExtra(c.smtputf8)),
|
|
message.MakeAuthProp("header", "s", r.Sig.Selector.XName(c.smtputf8), true, r.Sig.Selector.ASCIIExtra(c.smtputf8)),
|
|
message.MakeAuthProp("header", "a", r.Sig.Algorithm(), false, ""),
|
|
message.MakeAuthProp("header", "b", sig, false, ""), // ../rfc/6008:147
|
|
}
|
|
domain = r.Sig.Domain
|
|
selector = r.Sig.Selector
|
|
if r.Sig.Identity != nil {
|
|
props = append(props, message.MakeAuthProp("header", "i", r.Sig.Identity.String(), true, ""))
|
|
identity = r.Sig.Identity
|
|
}
|
|
if r.RecordAuthentic {
|
|
comment += "with dnssec"
|
|
} else {
|
|
comment += "without dnssec"
|
|
}
|
|
}
|
|
var errmsg string
|
|
if r.Err != nil {
|
|
errmsg = r.Err.Error()
|
|
}
|
|
authResAddDKIM(string(r.Status), comment, errmsg, props)
|
|
c.log.Debugx("dkim verification result", r.Err, mlog.Field("index", i), mlog.Field("mailfrom", c.mailFrom), mlog.Field("status", r.Status), mlog.Field("domain", domain), mlog.Field("selector", selector), mlog.Field("identity", identity))
|
|
}
|
|
|
|
// Add SPF results to Authentication-Results header. ../rfc/7208:2141
|
|
var spfIdentity *dns.Domain
|
|
var mailFromValidation = store.ValidationUnknown
|
|
var ehloValidation = store.ValidationUnknown
|
|
switch receivedSPF.Identity {
|
|
case spf.ReceivedHELO:
|
|
if len(spfArgs.HelloDomain.IP) == 0 {
|
|
spfIdentity = &spfArgs.HelloDomain.Domain
|
|
}
|
|
ehloValidation = store.SPFValidation(receivedSPF.Result)
|
|
case spf.ReceivedMailFrom:
|
|
spfIdentity = &spfArgs.MailFromDomain
|
|
mailFromValidation = store.SPFValidation(receivedSPF.Result)
|
|
}
|
|
var props []message.AuthProp
|
|
if spfIdentity != nil {
|
|
props = []message.AuthProp{message.MakeAuthProp("smtp", string(receivedSPF.Identity), spfIdentity.XName(c.smtputf8), true, spfIdentity.ASCIIExtra(c.smtputf8))}
|
|
}
|
|
var spfComment string
|
|
if spfAuthentic {
|
|
spfComment = "with dnssec"
|
|
} else {
|
|
spfComment = "without dnssec"
|
|
}
|
|
authResults.Methods = append(authResults.Methods, message.AuthMethod{
|
|
Method: "spf",
|
|
Result: string(receivedSPF.Result),
|
|
Comment: spfComment,
|
|
Props: props,
|
|
})
|
|
switch receivedSPF.Result {
|
|
case spf.StatusPass:
|
|
c.log.Debug("spf pass", mlog.Field("ip", spfArgs.RemoteIP), mlog.Field("mailfromdomain", spfArgs.MailFromDomain.ASCII)) // todo: log the domain that was actually verified.
|
|
case spf.StatusFail:
|
|
if spfExpl != "" {
|
|
// Filter out potentially hostile text. ../rfc/7208:2529
|
|
for _, b := range []byte(spfExpl) {
|
|
if b < ' ' || b >= 0x7f {
|
|
spfExpl = ""
|
|
break
|
|
}
|
|
}
|
|
if spfExpl != "" {
|
|
if len(spfExpl) > 800 {
|
|
spfExpl = spfExpl[:797] + "..."
|
|
}
|
|
spfExpl = "remote claims: " + spfExpl
|
|
}
|
|
}
|
|
if spfExpl == "" {
|
|
spfExpl = fmt.Sprintf("your ip %s is not on the SPF allowlist for domain %s", spfArgs.RemoteIP, spfDomain.ASCII)
|
|
}
|
|
c.log.Info("spf fail", mlog.Field("explanation", spfExpl)) // todo future: get this to the client. how? in smtp session in case of a reject due to dmarc fail?
|
|
case spf.StatusTemperror:
|
|
c.log.Infox("spf temperror", spfErr)
|
|
case spf.StatusPermerror:
|
|
c.log.Infox("spf permerror", spfErr)
|
|
case spf.StatusNone, spf.StatusNeutral, spf.StatusSoftfail:
|
|
default:
|
|
c.log.Error("unknown spf status, treating as None/Neutral", mlog.Field("status", receivedSPF.Result))
|
|
receivedSPF.Result = spf.StatusNone
|
|
}
|
|
|
|
// DMARC
|
|
var dmarcUse bool
|
|
var dmarcResult dmarc.Result
|
|
const applyRandomPercentage = true
|
|
// dmarcMethod is added to authResults when delivering to recipients: accounts can
|
|
// have different policy override rules.
|
|
var dmarcMethod message.AuthMethod
|
|
var msgFromValidation = store.ValidationNone
|
|
if msgFrom.IsZero() {
|
|
dmarcResult.Status = dmarc.StatusNone
|
|
dmarcMethod = message.AuthMethod{
|
|
Method: "dmarc",
|
|
Result: string(dmarcResult.Status),
|
|
}
|
|
} else {
|
|
msgFromValidation = alignment(ctx, msgFrom.Domain, dkimResults, receivedSPF.Result, spfIdentity)
|
|
|
|
// We are doing the DMARC evaluation now. But we only store it for inclusion in an
|
|
// aggregate report when we actually use it. We use an evaluation for each
|
|
// recipient, with each a potentially different result due to mailing
|
|
// list/forwarding configuration. If we reject a message due to being spam, we
|
|
// don't want to spend any resources for the sender domain, and we don't want to
|
|
// give the sender any more information about us, so we won't record the
|
|
// evaluation.
|
|
// todo future: also not send for first-time senders? they could be spammers getting through our filter, don't want to give them insights either. though we currently would have no reasonable way to decide if they are still reputationless at the time we are composing/sending aggregate reports.
|
|
|
|
dmarcctx, dmarccancel := context.WithTimeout(ctx, time.Minute)
|
|
defer dmarccancel()
|
|
dmarcUse, dmarcResult = dmarc.Verify(dmarcctx, c.resolver, msgFrom.Domain, dkimResults, receivedSPF.Result, spfIdentity, applyRandomPercentage)
|
|
dmarccancel()
|
|
var comment string
|
|
if dmarcResult.RecordAuthentic {
|
|
comment = "with dnssec"
|
|
} else {
|
|
comment = "without dnssec"
|
|
}
|
|
dmarcMethod = message.AuthMethod{
|
|
Method: "dmarc",
|
|
Result: string(dmarcResult.Status),
|
|
Comment: comment,
|
|
Props: []message.AuthProp{
|
|
// ../rfc/7489:1489
|
|
message.MakeAuthProp("header", "from", msgFrom.Domain.ASCII, true, msgFrom.Domain.ASCIIExtra(c.smtputf8)),
|
|
},
|
|
}
|
|
|
|
if dmarcResult.Status == dmarc.StatusPass && msgFromValidation == store.ValidationRelaxed {
|
|
msgFromValidation = store.ValidationDMARC
|
|
}
|
|
|
|
// todo future: consider enforcing an spf (soft)fail if there is no dmarc policy or the dmarc policy is none. ../rfc/7489:1507
|
|
}
|
|
c.log.Debug("dmarc verification", mlog.Field("result", dmarcResult.Status), mlog.Field("domain", msgFrom.Domain))
|
|
|
|
// Prepare for analyzing content, calculating reputation.
|
|
ipmasked1, ipmasked2, ipmasked3 := ipmasked(c.remoteIP)
|
|
var verifiedDKIMDomains []string
|
|
dkimSeen := map[string]bool{}
|
|
for _, r := range dkimResults {
|
|
// A message can have multiple signatures for the same identity. For example when
|
|
// signing the message multiple times with different algorithms (rsa and ed25519).
|
|
if r.Status != dkim.StatusPass {
|
|
continue
|
|
}
|
|
d := r.Sig.Domain.Name()
|
|
if !dkimSeen[d] {
|
|
dkimSeen[d] = true
|
|
verifiedDKIMDomains = append(verifiedDKIMDomains, d)
|
|
}
|
|
}
|
|
|
|
// When we deliver, we try to remove from rejects mailbox based on message-id.
|
|
// We'll parse it when we need it, but it is the same for each recipient.
|
|
var messageID string
|
|
var parsedMessageID bool
|
|
|
|
// We build up a DSN for each failed recipient. If we have recipients in dsnMsg
|
|
// after processing, we queue the DSN. Unless all recipients failed, in which case
|
|
// we may just fail the mail transaction instead (could be common for failure to
|
|
// deliver to a single recipient, e.g. for junk mail).
|
|
// ../rfc/3464:436
|
|
type deliverError struct {
|
|
rcptTo smtp.Path
|
|
code int
|
|
secode string
|
|
userError bool
|
|
errmsg string
|
|
}
|
|
var deliverErrors []deliverError
|
|
addError := func(rcptAcc rcptAccount, code int, secode string, userError bool, errmsg string) {
|
|
e := deliverError{rcptAcc.rcptTo, code, secode, userError, errmsg}
|
|
c.log.Info("deliver error", mlog.Field("rcptto", e.rcptTo), mlog.Field("code", code), mlog.Field("secode", "secode"), mlog.Field("usererror", userError), mlog.Field("errmsg", errmsg))
|
|
deliverErrors = append(deliverErrors, e)
|
|
}
|
|
|
|
// For each recipient, do final spam analysis and delivery.
|
|
for _, rcptAcc := range c.recipients {
|
|
log := c.log.Fields(mlog.Field("mailfrom", c.mailFrom), mlog.Field("rcptto", rcptAcc.rcptTo))
|
|
|
|
// If this is not a valid local user, we send back a DSN. This can only happen when
|
|
// there are also valid recipients, and only when remote is SPF-verified, so the DSN
|
|
// should not cause backscatter.
|
|
// In case of serious errors, we abort the transaction. We may have already
|
|
// delivered some messages. Perhaps it would be better to continue with other
|
|
// deliveries, and return an error at the end? Though the failure conditions will
|
|
// probably prevent any other successful deliveries too...
|
|
// We'll continue delivering to other recipients. ../rfc/5321:3275
|
|
if !rcptAcc.local {
|
|
metricDelivery.WithLabelValues("unknownuser", "").Inc()
|
|
addError(rcptAcc, smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, true, "no such user")
|
|
continue
|
|
}
|
|
|
|
acc, err := store.OpenAccount(rcptAcc.accountName)
|
|
if err != nil {
|
|
log.Errorx("open account", err, mlog.Field("account", rcptAcc.accountName))
|
|
metricDelivery.WithLabelValues("accounterror", "").Inc()
|
|
addError(rcptAcc, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing")
|
|
continue
|
|
}
|
|
defer func() {
|
|
if acc != nil {
|
|
err := acc.Close()
|
|
log.Check(err, "closing account after delivery")
|
|
}
|
|
}()
|
|
|
|
// We don't want to let a single IP or network deliver too many messages to an
|
|
// account. They may fill up the mailbox, either with messages that have to be
|
|
// purged, or by filling the disk. We check both cases for IP's and networks.
|
|
var rateError bool // Whether returned error represents a rate error.
|
|
err = acc.DB.Read(ctx, func(tx *bstore.Tx) (retErr error) {
|
|
now := time.Now()
|
|
defer func() {
|
|
log.Debugx("checking message and size delivery rates", retErr, mlog.Field("duration", time.Since(now)))
|
|
}()
|
|
|
|
checkCount := func(msg store.Message, window time.Duration, limit int) {
|
|
if retErr != nil {
|
|
return
|
|
}
|
|
q := bstore.QueryTx[store.Message](tx)
|
|
q.FilterNonzero(msg)
|
|
q.FilterGreater("Received", now.Add(-window))
|
|
q.FilterEqual("Expunged", false)
|
|
n, err := q.Count()
|
|
if err != nil {
|
|
retErr = err
|
|
return
|
|
}
|
|
if n >= limit {
|
|
rateError = true
|
|
retErr = fmt.Errorf("more than %d messages in past %s from your ip/network", limit, window)
|
|
}
|
|
}
|
|
|
|
checkSize := func(msg store.Message, window time.Duration, limit int64) {
|
|
if retErr != nil {
|
|
return
|
|
}
|
|
q := bstore.QueryTx[store.Message](tx)
|
|
q.FilterNonzero(msg)
|
|
q.FilterGreater("Received", now.Add(-window))
|
|
q.FilterEqual("Expunged", false)
|
|
size := msgWriter.Size
|
|
err := q.ForEach(func(v store.Message) error {
|
|
size += v.Size
|
|
return nil
|
|
})
|
|
if err != nil {
|
|
retErr = err
|
|
return
|
|
}
|
|
if size > limit {
|
|
rateError = true
|
|
retErr = fmt.Errorf("more than %d bytes in past %s from your ip/network", limit, window)
|
|
}
|
|
}
|
|
|
|
// todo future: make these configurable
|
|
// todo: should we have a limit for forwarded messages? they are stored with empty RemoteIPMasked*
|
|
|
|
const day = 24 * time.Hour
|
|
checkCount(store.Message{RemoteIPMasked1: ipmasked1}, time.Minute, limitIPMasked1MessagesPerMinute)
|
|
checkCount(store.Message{RemoteIPMasked1: ipmasked1}, day, 20*500)
|
|
checkCount(store.Message{RemoteIPMasked2: ipmasked2}, time.Minute, 1500)
|
|
checkCount(store.Message{RemoteIPMasked2: ipmasked2}, day, 20*1500)
|
|
checkCount(store.Message{RemoteIPMasked3: ipmasked3}, time.Minute, 4500)
|
|
checkCount(store.Message{RemoteIPMasked3: ipmasked3}, day, 20*4500)
|
|
|
|
const MB = 1024 * 1024
|
|
checkSize(store.Message{RemoteIPMasked1: ipmasked1}, time.Minute, limitIPMasked1SizePerMinute)
|
|
checkSize(store.Message{RemoteIPMasked1: ipmasked1}, day, 3*1000*MB)
|
|
checkSize(store.Message{RemoteIPMasked2: ipmasked2}, time.Minute, 3000*MB)
|
|
checkSize(store.Message{RemoteIPMasked2: ipmasked2}, day, 3*3000*MB)
|
|
checkSize(store.Message{RemoteIPMasked3: ipmasked3}, time.Minute, 9000*MB)
|
|
checkSize(store.Message{RemoteIPMasked3: ipmasked3}, day, 3*9000*MB)
|
|
|
|
return retErr
|
|
})
|
|
if err != nil && !rateError {
|
|
log.Errorx("checking delivery rates", err)
|
|
metricDelivery.WithLabelValues("checkrates", "").Inc()
|
|
addError(rcptAcc, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing")
|
|
continue
|
|
} else if err != nil {
|
|
log.Debugx("refusing due to high delivery rate", err)
|
|
metricDelivery.WithLabelValues("highrate", "").Inc()
|
|
c.setSlow(true)
|
|
addError(rcptAcc, smtp.C452StorageFull, smtp.SeMailbox2Full2, true, err.Error())
|
|
continue
|
|
}
|
|
|
|
m := store.Message{
|
|
Received: time.Now(),
|
|
RemoteIP: c.remoteIP.String(),
|
|
RemoteIPMasked1: ipmasked1,
|
|
RemoteIPMasked2: ipmasked2,
|
|
RemoteIPMasked3: ipmasked3,
|
|
EHLODomain: c.hello.Domain.Name(),
|
|
MailFrom: c.mailFrom.String(),
|
|
MailFromLocalpart: c.mailFrom.Localpart,
|
|
MailFromDomain: c.mailFrom.IPDomain.Domain.Name(),
|
|
RcptToLocalpart: rcptAcc.rcptTo.Localpart,
|
|
RcptToDomain: rcptAcc.rcptTo.IPDomain.Domain.Name(),
|
|
MsgFromLocalpart: msgFrom.Localpart,
|
|
MsgFromDomain: msgFrom.Domain.Name(),
|
|
MsgFromOrgDomain: publicsuffix.Lookup(ctx, msgFrom.Domain).Name(),
|
|
EHLOValidated: ehloValidation == store.ValidationPass,
|
|
MailFromValidated: mailFromValidation == store.ValidationPass,
|
|
MsgFromValidated: msgFromValidation == store.ValidationStrict || msgFromValidation == store.ValidationDMARC || msgFromValidation == store.ValidationRelaxed,
|
|
EHLOValidation: ehloValidation,
|
|
MailFromValidation: mailFromValidation,
|
|
MsgFromValidation: msgFromValidation,
|
|
DKIMDomains: verifiedDKIMDomains,
|
|
Size: msgWriter.Size,
|
|
}
|
|
if c.tls {
|
|
tlsState := c.conn.(*tls.Conn).ConnectionState()
|
|
m.ReceivedTLSVersion = tlsState.Version
|
|
m.ReceivedTLSCipherSuite = tlsState.CipherSuite
|
|
if c.requireTLS != nil {
|
|
m.ReceivedRequireTLS = *c.requireTLS
|
|
}
|
|
} else {
|
|
m.ReceivedTLSVersion = 1 // Signals plain text delivery.
|
|
}
|
|
|
|
d := delivery{&m, dataFile, rcptAcc, acc, msgFrom, c.dnsBLs, dmarcUse, dmarcResult, dkimResults, iprevStatus}
|
|
a := analyze(ctx, log, c.resolver, d)
|
|
|
|
// Any DMARC result override is stored in the evaluation for outgoing DMARC
|
|
// aggregate reports, and added to the Authentication-Results message header.
|
|
// We want to tell the sender that we have an override, e.g. for mailing lists, so
|
|
// they don't overestimate the potential damage of switching from p=none to
|
|
// p=reject.
|
|
var dmarcOverrides []string
|
|
if a.dmarcOverrideReason != "" {
|
|
dmarcOverrides = []string{a.dmarcOverrideReason}
|
|
}
|
|
if dmarcResult.Record != nil && !dmarcUse {
|
|
dmarcOverrides = append(dmarcOverrides, string(dmarcrpt.PolicyOverrideSampledOut))
|
|
}
|
|
|
|
// Add per-recipient DMARC method to Authentication-Results. Each account can have
|
|
// their own override rules, e.g. based on configured mailing lists/forwards.
|
|
// ../rfc/7489:1486
|
|
rcptDMARCMethod := dmarcMethod
|
|
if len(dmarcOverrides) > 0 {
|
|
if rcptDMARCMethod.Comment != "" {
|
|
rcptDMARCMethod.Comment += ", "
|
|
}
|
|
rcptDMARCMethod.Comment += "override " + strings.Join(dmarcOverrides, ",")
|
|
}
|
|
rcptAuthResults := authResults
|
|
rcptAuthResults.Methods = append([]message.AuthMethod{}, authResults.Methods...)
|
|
rcptAuthResults.Methods = append(rcptAuthResults.Methods, rcptDMARCMethod)
|
|
|
|
// Prepend reason as message header, for easy display in mail clients.
|
|
var xmox string
|
|
if a.reason != "" {
|
|
xmox = "X-Mox-Reason: " + a.reason + "\r\n"
|
|
}
|
|
xmox += a.headers
|
|
|
|
// ../rfc/5321:3204
|
|
// Received-SPF header goes before Received. ../rfc/7208:2038
|
|
m.MsgPrefix = []byte(
|
|
xmox +
|
|
"Delivered-To: " + rcptAcc.rcptTo.XString(c.smtputf8) + "\r\n" + // ../rfc/9228:274
|
|
"Return-Path: <" + c.mailFrom.String() + ">\r\n" + // ../rfc/5321:3300
|
|
rcptAuthResults.Header() +
|
|
receivedSPF.Header() +
|
|
recvHdrFor(rcptAcc.rcptTo.String()),
|
|
)
|
|
m.Size += int64(len(m.MsgPrefix))
|
|
|
|
// Store DMARC evaluation for inclusion in an aggregate report. Only if there is at
|
|
// least one reporting address: We don't want to needlessly store a row in a
|
|
// database for each delivery attempt. If we reject a message for being junk, we
|
|
// are also not going to send it a DMARC report. The DMARC check is done early in
|
|
// the analysis, we will report on rejects because of DMARC, because it could be
|
|
// valuable feedback about forwarded or mailing list messages.
|
|
// ../rfc/7489:1492
|
|
if !mox.Conf.Static.NoOutgoingDMARCReports && dmarcResult.Record != nil && len(dmarcResult.Record.AggregateReportAddresses) > 0 && (a.accept && !m.IsReject || a.reason == reasonDMARCPolicy) {
|
|
// Disposition holds our decision on whether to accept the message. Not what the
|
|
// DMARC evaluation resulted in. We can override, e.g. because of mailing lists,
|
|
// forwarding, or local policy.
|
|
// We treat quarantine as reject, so never claim to quarantine.
|
|
// ../rfc/7489:1691
|
|
disposition := dmarcrpt.DispositionNone
|
|
if !a.accept {
|
|
disposition = dmarcrpt.DispositionReject
|
|
}
|
|
|
|
// unknownDomain returns whether the sender is domain with which this account has
|
|
// not had positive interaction.
|
|
unknownDomain := func() (unknown bool) {
|
|
err := acc.DB.Read(ctx, func(tx *bstore.Tx) (err error) {
|
|
// See if we received a non-junk message from this organizational domain.
|
|
q := bstore.QueryTx[store.Message](tx)
|
|
q.FilterNonzero(store.Message{MsgFromOrgDomain: m.MsgFromOrgDomain})
|
|
q.FilterEqual("Notjunk", true)
|
|
q.FilterEqual("IsReject", false)
|
|
exists, err := q.Exists()
|
|
if err != nil {
|
|
return fmt.Errorf("querying for non-junk message from organizational domain: %v", err)
|
|
}
|
|
if exists {
|
|
return nil
|
|
}
|
|
|
|
// See if we sent a message to this organizational domain.
|
|
qr := bstore.QueryTx[store.Recipient](tx)
|
|
qr.FilterNonzero(store.Recipient{OrgDomain: m.MsgFromOrgDomain})
|
|
exists, err = qr.Exists()
|
|
if err != nil {
|
|
return fmt.Errorf("querying for message sent to organizational domain: %v", err)
|
|
}
|
|
if !exists {
|
|
unknown = true
|
|
}
|
|
return nil
|
|
})
|
|
if err != nil {
|
|
log.Errorx("checking if sender is unknown domain, for dmarc aggregate report evaluation", err)
|
|
}
|
|
return
|
|
}
|
|
|
|
r := dmarcResult.Record
|
|
addresses := make([]string, len(r.AggregateReportAddresses))
|
|
for i, a := range r.AggregateReportAddresses {
|
|
addresses[i] = a.String()
|
|
}
|
|
sp := dmarcrpt.Disposition(r.SubdomainPolicy)
|
|
if r.SubdomainPolicy == dmarc.PolicyEmpty {
|
|
sp = dmarcrpt.Disposition(r.Policy)
|
|
}
|
|
eval := dmarcdb.Evaluation{
|
|
// Evaluated and IntervalHours set by AddEvaluation.
|
|
PolicyDomain: dmarcResult.Domain.Name(),
|
|
|
|
// Optional evaluations don't cause a report to be sent, but will be included.
|
|
// Useful for automated inter-mailer messages, we don't want to get in a reporting
|
|
// loop. We also don't want to be used for sending reports to unsuspecting domains
|
|
// we have no relation with.
|
|
// todo: would it make sense to also mark some percentage of mailing-list-policy-overrides optional? to lower the load on mail servers of folks sending to large mailing lists.
|
|
Optional: rcptAcc.destination.DMARCReports || rcptAcc.destination.HostTLSReports || rcptAcc.destination.DomainTLSReports || a.reason == reasonDMARCPolicy && unknownDomain(),
|
|
|
|
Addresses: addresses,
|
|
|
|
PolicyPublished: dmarcrpt.PolicyPublished{
|
|
Domain: dmarcResult.Domain.Name(),
|
|
ADKIM: dmarcrpt.Alignment(r.ADKIM),
|
|
ASPF: dmarcrpt.Alignment(r.ASPF),
|
|
Policy: dmarcrpt.Disposition(r.Policy),
|
|
SubdomainPolicy: sp,
|
|
Percentage: r.Percentage,
|
|
// We don't save ReportingOptions, we don't do per-message failure reporting.
|
|
},
|
|
SourceIP: c.remoteIP.String(),
|
|
Disposition: disposition,
|
|
AlignedDKIMPass: dmarcResult.AlignedDKIMPass,
|
|
AlignedSPFPass: dmarcResult.AlignedSPFPass,
|
|
EnvelopeTo: rcptAcc.rcptTo.IPDomain.String(),
|
|
EnvelopeFrom: c.mailFrom.IPDomain.String(),
|
|
HeaderFrom: msgFrom.Domain.Name(),
|
|
}
|
|
|
|
for _, s := range dmarcOverrides {
|
|
reason := dmarcrpt.PolicyOverrideReason{Type: dmarcrpt.PolicyOverride(s)}
|
|
eval.OverrideReasons = append(eval.OverrideReasons, reason)
|
|
}
|
|
|
|
// We'll include all signatures for the organizational domain, even if they weren't
|
|
// relevant due to strict alignment requirement.
|
|
for _, dkimResult := range dkimResults {
|
|
if dkimResult.Sig == nil || publicsuffix.Lookup(ctx, msgFrom.Domain) != publicsuffix.Lookup(ctx, dkimResult.Sig.Domain) {
|
|
continue
|
|
}
|
|
r := dmarcrpt.DKIMAuthResult{
|
|
Domain: dkimResult.Sig.Domain.Name(),
|
|
Selector: dkimResult.Sig.Selector.ASCII,
|
|
Result: dmarcrpt.DKIMResult(dkimResult.Status),
|
|
}
|
|
eval.DKIMResults = append(eval.DKIMResults, r)
|
|
}
|
|
|
|
switch receivedSPF.Identity {
|
|
case spf.ReceivedHELO:
|
|
spfAuthResult := dmarcrpt.SPFAuthResult{
|
|
Domain: spfArgs.HelloDomain.String(), // Can be unicode and also IP.
|
|
Scope: dmarcrpt.SPFDomainScopeHelo,
|
|
Result: dmarcrpt.SPFResult(receivedSPF.Result),
|
|
}
|
|
eval.SPFResults = []dmarcrpt.SPFAuthResult{spfAuthResult}
|
|
case spf.ReceivedMailFrom:
|
|
spfAuthResult := dmarcrpt.SPFAuthResult{
|
|
Domain: spfArgs.MailFromDomain.Name(), // Can be unicode.
|
|
Scope: dmarcrpt.SPFDomainScopeMailFrom,
|
|
Result: dmarcrpt.SPFResult(receivedSPF.Result),
|
|
}
|
|
eval.SPFResults = []dmarcrpt.SPFAuthResult{spfAuthResult}
|
|
}
|
|
|
|
err := dmarcdb.AddEvaluation(ctx, dmarcResult.Record.AggregateReportingInterval, &eval)
|
|
log.Check(err, "adding dmarc evaluation to database for aggregate report")
|
|
}
|
|
|
|
if !a.accept {
|
|
conf, _ := acc.Conf()
|
|
if conf.RejectsMailbox != "" {
|
|
present, _, messagehash, err := rejectPresent(log, acc, conf.RejectsMailbox, &m, dataFile)
|
|
if err != nil {
|
|
log.Errorx("checking whether reject is already present", err)
|
|
} else if !present {
|
|
m.IsReject = true
|
|
m.Seen = true // We don't want to draw attention.
|
|
// Regular automatic junk flags configuration applies to these messages. The
|
|
// default is to treat these as neutral, so they won't cause outright rejections
|
|
// due to reputation for later delivery attempts.
|
|
m.MessageHash = messagehash
|
|
acc.WithWLock(func() {
|
|
hasSpace := true
|
|
var err error
|
|
if !conf.KeepRejects {
|
|
hasSpace, err = acc.TidyRejectsMailbox(c.log, conf.RejectsMailbox)
|
|
}
|
|
if err != nil {
|
|
log.Errorx("tidying rejects mailbox", err)
|
|
} else if hasSpace {
|
|
if err := acc.DeliverMailbox(log, conf.RejectsMailbox, &m, dataFile); err != nil {
|
|
log.Errorx("delivering spammy mail to rejects mailbox", err)
|
|
} else {
|
|
log.Info("delivered spammy mail to rejects mailbox")
|
|
}
|
|
} else {
|
|
log.Info("not storing spammy mail to full rejects mailbox")
|
|
}
|
|
})
|
|
} else {
|
|
log.Info("reject message is already present, ignoring")
|
|
}
|
|
}
|
|
|
|
log.Info("incoming message rejected", mlog.Field("reason", a.reason), mlog.Field("msgfrom", msgFrom))
|
|
metricDelivery.WithLabelValues("reject", a.reason).Inc()
|
|
c.setSlow(true)
|
|
addError(rcptAcc, a.code, a.secode, a.userError, a.errmsg)
|
|
continue
|
|
}
|
|
|
|
delayFirstTime := true
|
|
if a.dmarcReport != nil {
|
|
// todo future: add rate limiting to prevent DoS attacks. ../rfc/7489:2570
|
|
if err := dmarcdb.AddReport(ctx, a.dmarcReport, msgFrom.Domain); err != nil {
|
|
log.Errorx("saving dmarc aggregate report in database", err)
|
|
} else {
|
|
log.Info("dmarc aggregate report processed")
|
|
m.Flags.Seen = true
|
|
delayFirstTime = false
|
|
}
|
|
}
|
|
if a.tlsReport != nil {
|
|
// todo future: add rate limiting to prevent DoS attacks.
|
|
if err := tlsrptdb.AddReport(ctx, msgFrom.Domain, c.mailFrom.String(), rcptAcc.destination.HostTLSReports, a.tlsReport); err != nil {
|
|
log.Errorx("saving TLSRPT report in database", err)
|
|
} else {
|
|
log.Info("tlsrpt report processed")
|
|
m.Flags.Seen = true
|
|
delayFirstTime = false
|
|
}
|
|
}
|
|
|
|
// If this is a first-time sender and not a forwarded message, wait before actually
|
|
// delivering. If this turns out to be a spammer, we've kept one of their
|
|
// connections busy.
|
|
if delayFirstTime && !m.IsForward && a.reason == reasonNoBadSignals && c.firstTimeSenderDelay > 0 {
|
|
log.Debug("delaying before delivering from sender without reputation", mlog.Field("delay", c.firstTimeSenderDelay))
|
|
mox.Sleep(mox.Context, c.firstTimeSenderDelay)
|
|
}
|
|
|
|
// Gather the message-id before we deliver and the file may be consumed.
|
|
if !parsedMessageID {
|
|
if p, err := message.Parse(c.log, false, store.FileMsgReader(m.MsgPrefix, dataFile)); err != nil {
|
|
log.Infox("parsing message for message-id", err)
|
|
} else if header, err := p.Header(); err != nil {
|
|
log.Infox("parsing message header for message-id", err)
|
|
} else {
|
|
messageID = header.Get("Message-Id")
|
|
}
|
|
}
|
|
|
|
if Localserve {
|
|
code, timeout := localserveNeedsError(rcptAcc.rcptTo.Localpart)
|
|
if timeout {
|
|
c.log.Info("timing out due to special localpart")
|
|
mox.Sleep(mox.Context, time.Hour)
|
|
xsmtpServerErrorf(codes{smtp.C451LocalErr, smtp.SeOther00}, "timing out delivery due to special localpart")
|
|
} else if code != 0 {
|
|
c.log.Info("failure due to special localpart", mlog.Field("code", code))
|
|
metricDelivery.WithLabelValues("delivererror", "localserve").Inc()
|
|
addError(rcptAcc, code, smtp.SeOther00, false, fmt.Sprintf("failure with code %d due to special localpart", code))
|
|
}
|
|
}
|
|
acc.WithWLock(func() {
|
|
if err := acc.DeliverMailbox(log, a.mailbox, &m, dataFile); err != nil {
|
|
log.Errorx("delivering", err)
|
|
metricDelivery.WithLabelValues("delivererror", a.reason).Inc()
|
|
addError(rcptAcc, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing")
|
|
return
|
|
}
|
|
metricDelivery.WithLabelValues("delivered", a.reason).Inc()
|
|
log.Info("incoming message delivered", mlog.Field("reason", a.reason), mlog.Field("msgfrom", msgFrom))
|
|
|
|
conf, _ := acc.Conf()
|
|
if conf.RejectsMailbox != "" && m.MessageID != "" {
|
|
if err := acc.RejectsRemove(log, conf.RejectsMailbox, m.MessageID); err != nil {
|
|
log.Errorx("removing message from rejects mailbox", err, mlog.Field("messageid", messageID))
|
|
}
|
|
}
|
|
})
|
|
|
|
err = acc.Close()
|
|
log.Check(err, "closing account after delivering")
|
|
acc = nil
|
|
}
|
|
|
|
// If all recipients failed to deliver, return an error.
|
|
if len(c.recipients) == len(deliverErrors) {
|
|
same := true
|
|
e0 := deliverErrors[0]
|
|
var serverError bool
|
|
var msgs []string
|
|
major := 4
|
|
for _, e := range deliverErrors {
|
|
serverError = serverError || !e.userError
|
|
if e.code != e0.code || e.secode != e0.secode {
|
|
same = false
|
|
}
|
|
msgs = append(msgs, e.errmsg)
|
|
if e.code >= 500 {
|
|
major = 5
|
|
}
|
|
}
|
|
if same {
|
|
xsmtpErrorf(e0.code, e0.secode, !serverError, "%s", strings.Join(msgs, "\n"))
|
|
}
|
|
|
|
// Not all failures had the same error. We'll return each error on a separate line.
|
|
lines := []string{}
|
|
for _, e := range deliverErrors {
|
|
s := fmt.Sprintf("%d %d.%s %s", e.code, e.code/100, e.secode, e.errmsg)
|
|
lines = append(lines, s)
|
|
}
|
|
code := smtp.C451LocalErr
|
|
secode := smtp.SeSys3Other0
|
|
if major == 5 {
|
|
code = smtp.C554TransactionFailed
|
|
}
|
|
lines = append(lines, "multiple errors")
|
|
xsmtpErrorf(code, secode, !serverError, strings.Join(lines, "\n"))
|
|
}
|
|
// Generate one DSN for all failed recipients.
|
|
if len(deliverErrors) > 0 {
|
|
now := time.Now()
|
|
dsnMsg := dsn.Message{
|
|
SMTPUTF8: c.smtputf8,
|
|
From: smtp.Path{Localpart: "postmaster", IPDomain: deliverErrors[0].rcptTo.IPDomain},
|
|
To: *c.mailFrom,
|
|
Subject: "mail delivery failure",
|
|
References: messageID,
|
|
|
|
// Per-message details.
|
|
ReportingMTA: mox.Conf.Static.HostnameDomain.ASCII,
|
|
ReceivedFromMTA: smtp.Ehlo{Name: c.hello, ConnIP: c.remoteIP},
|
|
ArrivalDate: now,
|
|
}
|
|
|
|
if len(deliverErrors) > 1 {
|
|
dsnMsg.TextBody = "Multiple delivery failures occurred.\n\n"
|
|
}
|
|
|
|
for _, e := range deliverErrors {
|
|
kind := "Permanent"
|
|
if e.code/100 == 4 {
|
|
kind = "Transient"
|
|
}
|
|
dsnMsg.TextBody += fmt.Sprintf("%s delivery failure to:\n\n\t%s\n\nError:\n\n\t%s\n\n", kind, e.errmsg, e.rcptTo.XString(false))
|
|
rcpt := dsn.Recipient{
|
|
FinalRecipient: e.rcptTo,
|
|
Action: dsn.Failed,
|
|
Status: fmt.Sprintf("%d.%s", e.code/100, e.secode),
|
|
LastAttemptDate: now,
|
|
}
|
|
dsnMsg.Recipients = append(dsnMsg.Recipients, rcpt)
|
|
}
|
|
|
|
header, err := message.ReadHeaders(bufio.NewReader(&moxio.AtReader{R: dataFile}))
|
|
if err != nil {
|
|
c.log.Errorx("reading headers of incoming message for dsn, continuing dsn without headers", err)
|
|
}
|
|
dsnMsg.Original = header
|
|
|
|
if Localserve {
|
|
c.log.Error("not queueing dsn for incoming delivery due to localserve")
|
|
} else if err := queueDSN(context.TODO(), c, *c.mailFrom, dsnMsg, c.requireTLS != nil && *c.requireTLS); err != nil {
|
|
metricServerErrors.WithLabelValues("queuedsn").Inc()
|
|
c.log.Errorx("queuing DSN for incoming delivery, no DSN sent", err)
|
|
}
|
|
}
|
|
|
|
c.transactionGood++
|
|
c.transactionBad-- // Compensate for early earlier pessimistic increase.
|
|
c.rset()
|
|
c.writecodeline(smtp.C250Completed, smtp.SeMailbox2Other0, "it is done", nil)
|
|
}
|
|
|
|
// ecode returns either ecode, or a more specific error based on err.
|
|
// For example, ecode can be turned from an "other system" error into a "mail
|
|
// system full" if the error indicates no disk space is available.
|
|
func errCodes(code int, ecode string, err error) codes {
|
|
switch {
|
|
case moxio.IsStorageSpace(err):
|
|
switch ecode {
|
|
case smtp.SeMailbox2Other0:
|
|
if code == smtp.C451LocalErr {
|
|
code = smtp.C452StorageFull
|
|
}
|
|
ecode = smtp.SeMailbox2Full2
|
|
case smtp.SeSys3Other0:
|
|
if code == smtp.C451LocalErr {
|
|
code = smtp.C452StorageFull
|
|
}
|
|
ecode = smtp.SeSys3StorageFull1
|
|
}
|
|
}
|
|
return codes{code, ecode}
|
|
}
|
|
|
|
// ../rfc/5321:2079
|
|
func (c *conn) cmdRset(p *parser) {
|
|
// ../rfc/5321:2106
|
|
p.xend()
|
|
|
|
c.rset()
|
|
c.bwritecodeline(smtp.C250Completed, smtp.SeOther00, "all clear", nil)
|
|
}
|
|
|
|
// ../rfc/5321:2108 ../rfc/5321:1222
|
|
func (c *conn) cmdVrfy(p *parser) {
|
|
// No EHLO/HELO needed.
|
|
// ../rfc/5321:2448
|
|
|
|
// ../rfc/5321:2119 ../rfc/6531:641
|
|
p.xspace()
|
|
p.xstring()
|
|
if p.space() {
|
|
p.xtake("SMTPUTF8")
|
|
}
|
|
p.xend()
|
|
|
|
// todo future: we could support vrfy and expn for submission? though would need to see if its rfc defines it.
|
|
|
|
// ../rfc/5321:4239
|
|
xsmtpUserErrorf(smtp.C252WithoutVrfy, smtp.SePol7Other0, "no verify but will try delivery")
|
|
}
|
|
|
|
// ../rfc/5321:2135 ../rfc/5321:1272
|
|
func (c *conn) cmdExpn(p *parser) {
|
|
// No EHLO/HELO needed.
|
|
// ../rfc/5321:2448
|
|
|
|
// ../rfc/5321:2149 ../rfc/6531:645
|
|
p.xspace()
|
|
p.xstring()
|
|
if p.space() {
|
|
p.xtake("SMTPUTF8")
|
|
}
|
|
p.xend()
|
|
|
|
// ../rfc/5321:4239
|
|
xsmtpUserErrorf(smtp.C252WithoutVrfy, smtp.SePol7Other0, "no expand but will try delivery")
|
|
}
|
|
|
|
// ../rfc/5321:2151
|
|
func (c *conn) cmdHelp(p *parser) {
|
|
// Let's not strictly parse the request for help. We are ignoring the text anyway.
|
|
// ../rfc/5321:2166
|
|
|
|
c.bwritecodeline(smtp.C214Help, smtp.SeOther00, "see rfc 5321 (smtp)", nil)
|
|
}
|
|
|
|
// ../rfc/5321:2191
|
|
func (c *conn) cmdNoop(p *parser) {
|
|
// No idea why, but if an argument follows, it must adhere to the string ABNF production...
|
|
// ../rfc/5321:2203
|
|
if p.space() {
|
|
p.xstring()
|
|
}
|
|
p.xend()
|
|
|
|
c.bwritecodeline(smtp.C250Completed, smtp.SeOther00, "alrighty", nil)
|
|
}
|
|
|
|
// ../rfc/5321:2205
|
|
func (c *conn) cmdQuit(p *parser) {
|
|
// ../rfc/5321:2226
|
|
p.xend()
|
|
|
|
c.writecodeline(smtp.C221Closing, smtp.SeOther00, "okay thanks bye", nil)
|
|
panic(cleanClose)
|
|
}
|