mirror of
https://github.com/mjl-/mox.git
synced 2024-12-26 16:33:47 +03:00
5b20cba50a
we don't want external software to include internal details like mlog. slog.Logger is/will be the standard. we still have mlog for its helper functions, and its handler that logs in concise logfmt used by mox. packages that are not meant for reuse still pass around mlog.Log for convenience. we use golang.org/x/exp/slog because we also support the previous Go toolchain version. with the next Go release, we'll switch to the builtin slog.
90 lines
3.1 KiB
Go
90 lines
3.1 KiB
Go
package smtpclient
|
|
|
|
import (
|
|
"context"
|
|
"fmt"
|
|
"net"
|
|
"time"
|
|
|
|
"golang.org/x/exp/slog"
|
|
|
|
"github.com/mjl-/mox/dns"
|
|
"github.com/mjl-/mox/mlog"
|
|
"github.com/mjl-/mox/mox-"
|
|
)
|
|
|
|
// DialHook can be used during tests to override the regular dialer from being used.
|
|
var DialHook func(ctx context.Context, dialer Dialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error)
|
|
|
|
func dial(ctx context.Context, dialer Dialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
|
|
// todo: see if we can remove this function and DialHook in favor of the Dialer interface.
|
|
|
|
if DialHook != nil {
|
|
return DialHook(ctx, dialer, timeout, addr, laddr)
|
|
}
|
|
|
|
// If this is a net.Dialer, use its settings and add the timeout and localaddr.
|
|
// This is the typical case, but SOCKS5 support can use a different dialer.
|
|
if d, ok := dialer.(*net.Dialer); ok {
|
|
nd := *d
|
|
nd.Timeout = timeout
|
|
nd.LocalAddr = laddr
|
|
return nd.DialContext(ctx, "tcp", addr)
|
|
}
|
|
return dialer.DialContext(ctx, "tcp", addr)
|
|
}
|
|
|
|
// Dialer is used to dial mail servers, an interface to facilitate testing.
|
|
type Dialer interface {
|
|
DialContext(ctx context.Context, network, addr string) (c net.Conn, err error)
|
|
}
|
|
|
|
// Dial connects to host by dialing ips, taking previous attempts in dialedIPs into
|
|
// accounts (for greylisting, blocklisting and ipv4/ipv6).
|
|
//
|
|
// If the previous attempt used IPv4, this attempt will use IPv6 (in case one of
|
|
// the IPs is in a DNSBL).
|
|
// The second attempt for an address family we prefer the same IP as earlier, to
|
|
// increase our chances if remote is doing greylisting.
|
|
//
|
|
// Dial updates dialedIPs, callers may want to save it so it can be taken into
|
|
// account for future delivery attempts.
|
|
//
|
|
// If we have fully specified local SMTP listener IPs, we set those for the
|
|
// outgoing connection. The admin probably configured these same IPs in SPF, but
|
|
// others possibly not.
|
|
func Dial(ctx context.Context, elog *slog.Logger, dialer Dialer, host dns.IPDomain, ips []net.IP, port int, dialedIPs map[string][]net.IP) (conn net.Conn, ip net.IP, rerr error) {
|
|
log := mlog.New("smtpclient", elog)
|
|
timeout := 30 * time.Second
|
|
if deadline, ok := ctx.Deadline(); ok && len(ips) > 0 {
|
|
timeout = time.Until(deadline) / time.Duration(len(ips))
|
|
}
|
|
|
|
var lastErr error
|
|
var lastIP net.IP
|
|
for _, ip := range ips {
|
|
addr := net.JoinHostPort(ip.String(), fmt.Sprintf("%d", port))
|
|
log.Debug("dialing host", slog.String("addr", addr))
|
|
var laddr net.Addr
|
|
for _, lip := range mox.Conf.Static.SpecifiedSMTPListenIPs {
|
|
ipIs4 := ip.To4() != nil
|
|
lipIs4 := lip.To4() != nil
|
|
if ipIs4 == lipIs4 {
|
|
laddr = &net.TCPAddr{IP: lip}
|
|
break
|
|
}
|
|
}
|
|
conn, err := dial(ctx, dialer, timeout, addr, laddr)
|
|
if err == nil {
|
|
log.Debug("connected to host", slog.Any("host", host), slog.String("addr", addr), slog.Any("laddr", laddr))
|
|
name := host.String()
|
|
dialedIPs[name] = append(dialedIPs[name], ip)
|
|
return conn, ip, nil
|
|
}
|
|
log.Debugx("connection attempt", err, slog.Any("host", host), slog.String("addr", addr), slog.Any("laddr", laddr))
|
|
lastErr = err
|
|
lastIP = ip
|
|
}
|
|
// todo: possibly return all errors joined?
|
|
return nil, lastIP, lastErr
|
|
}
|