mox/vendor/golang.org/x/net/proxy/socks5.go

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new feature: when delivering messages from the queue, make it possible to use a "transport" the default transport is still just "direct delivery", where we connect to the destination domain's MX servers. other transports are: - regular smtp without authentication, this is relaying to a smarthost. - submission with authentication, e.g. to a third party email sending service. - direct delivery, but with with connections going through a socks proxy. this can be helpful if your ip is blocked, you need to get email out, and you have another IP that isn't blocked. keep in mind that for all of the above, appropriate SPF/DKIM settings have to be configured. the "dnscheck" for a domain does a check for any SOCKS IP in the SPF record. SPF for smtp/submission (ranges? includes?) and any DKIM requirements cannot really be checked. which transport is used can be configured through routes. routes can be set on an account, a domain, or globally. the routes are evaluated in that order, with the first match selecting the transport. these routes are evaluated for each delivery attempt. common selection criteria are recipient domain and sender domain, but also which delivery attempt this is. you could configured mox to attempt sending through a 3rd party from the 4th attempt onwards. routes and transports are optional. if no route matches, or an empty/zero transport is selected, normal direct delivery is done. we could already "submit" emails with 3rd party accounts with "sendmail". but we now support more SASL authentication mechanisms with SMTP (not only PLAIN, but also SCRAM-SHA-256, SCRAM-SHA-1 and CRAM-MD5), which sendmail now also supports. sendmail will use the most secure mechanism supported by the server, or the explicitly configured mechanism. for issue #36 by dmikushin. also based on earlier discussion on hackernews.
2023-06-16 19:38:28 +03:00
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package proxy
import (
"context"
"net"
"golang.org/x/net/internal/socks"
)
// SOCKS5 returns a Dialer that makes SOCKSv5 connections to the given
// address with an optional username and password.
// See RFC 1928 and RFC 1929.
func SOCKS5(network, address string, auth *Auth, forward Dialer) (Dialer, error) {
d := socks.NewDialer(network, address)
if forward != nil {
if f, ok := forward.(ContextDialer); ok {
d.ProxyDial = func(ctx context.Context, network string, address string) (net.Conn, error) {
return f.DialContext(ctx, network, address)
}
} else {
d.ProxyDial = func(ctx context.Context, network string, address string) (net.Conn, error) {
return dialContext(ctx, forward, network, address)
}
}
}
if auth != nil {
up := socks.UsernamePassword{
Username: auth.User,
Password: auth.Password,
}
d.AuthMethods = []socks.AuthMethod{
socks.AuthMethodNotRequired,
socks.AuthMethodUsernamePassword,
}
d.Authenticate = up.Authenticate
}
return d, nil
}