mirror of
https://github.com/mjl-/mox.git
synced 2024-12-26 16:33:47 +03:00
96 lines
3.1 KiB
Go
96 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
|
|
}
|