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.
This commit is contained in:
Mechiel Lukkien
2023-06-16 18:38:28 +02:00
parent 2eecf38842
commit 8096441f67
36 changed files with 3125 additions and 650 deletions

View File

@ -3,9 +3,14 @@ package queue
import (
"bufio"
"context"
"crypto/ed25519"
cryptorand "crypto/rand"
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"io"
"math/big"
"net"
"os"
"reflect"
@ -80,11 +85,11 @@ func TestQueue(t *testing.T) {
}
path := smtp.Path{Localpart: "mjl", IPDomain: dns.IPDomain{Domain: dns.Domain{ASCII: "mox.example"}}}
err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
_, err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
tcheck(t, err, "add message to queue for delivery")
mf2 := prepareFile(t)
err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, mf2, nil, false)
_, err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, mf2, nil, false)
tcheck(t, err, "add message to queue for delivery")
os.Remove(mf2.Name())
@ -120,11 +125,14 @@ func TestQueue(t *testing.T) {
// Override dial function. We'll make connecting fail for now.
resolver := dns.MockResolver{
A: map[string][]string{"mox.example.": {"127.0.0.1"}},
A: map[string][]string{
"mox.example.": {"127.0.0.1"},
"submission.example.": {"127.0.0.1"},
},
MX: map[string][]*net.MX{"mox.example.": {{Host: "mox.example", Pref: 10}}},
}
dialed := make(chan struct{}, 1)
dial = func(ctx context.Context, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dial = func(ctx context.Context, dialer contextDialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dialed <- struct{}{}
return nil, fmt.Errorf("failure from test")
}
@ -167,26 +175,20 @@ func TestQueue(t *testing.T) {
t.Fatalf("message mismatch, got %q, expected %q", string(msgbuf), testmsg)
}
n, err = Kick(ctxbg, msg.ID+1, "", "")
n, err = Kick(ctxbg, msg.ID+1, "", "", nil)
tcheck(t, err, "kick")
if n != 0 {
t.Fatalf("kick %d, expected 0", n)
}
n, err = Kick(ctxbg, msg.ID, "", "")
n, err = Kick(ctxbg, msg.ID, "", "", nil)
tcheck(t, err, "kick")
if n != 1 {
t.Fatalf("kicked %d, expected 1", n)
}
// Setting up a pipe. We'll start a fake smtp server on the server-side. And return the
// client-side to the invocation dial, for the attempted delivery from the queue.
// The delivery should succeed.
server, client := net.Pipe()
defer server.Close()
defer client.Close()
smtpdone := make(chan struct{})
go func() {
fakeSMTPServer := func(server net.Conn) {
// We do a minimal fake smtp server. We cannot import smtpserver.Serve due to cyclic dependencies.
fmt.Fprintf(server, "220 mox.example\r\n")
br := bufio.NewReader(server)
@ -205,42 +207,139 @@ func TestQueue(t *testing.T) {
fmt.Fprintf(server, "221 ok\r\n")
smtpdone <- struct{}{}
}()
dial = func(ctx context.Context, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dialed <- struct{}{}
return client, nil
}
launchWork(resolver, map[string]struct{}{})
timer.Reset(time.Second)
select {
case <-dialed:
select {
case <-smtpdone:
i := 0
for {
xmsgs, err := List(ctxbg)
tcheck(t, err, "list queue")
if len(xmsgs) == 0 {
break
}
i++
if i == 10 {
t.Fatalf("%d messages in queue, expected 0", len(xmsgs))
}
time.Sleep(100 * time.Millisecond)
}
case <-timer.C:
t.Fatalf("no deliver within 1s")
fakeSubmitServer := func(server net.Conn) {
// We do a minimal fake smtp server. We cannot import smtpserver.Serve due to cyclic dependencies.
fmt.Fprintf(server, "220 mox.example\r\n")
br := bufio.NewReader(server)
br.ReadString('\n') // Should be EHLO.
fmt.Fprintf(server, "250-localhost\r\n")
fmt.Fprintf(server, "250 AUTH PLAIN\r\n")
br.ReadString('\n') // Should be AUTH PLAIN
fmt.Fprintf(server, "235 2.7.0 auth ok\r\n")
br.ReadString('\n') // Should be MAIL FROM.
fmt.Fprintf(server, "250 ok\r\n")
br.ReadString('\n') // Should be RCPT TO.
fmt.Fprintf(server, "250 ok\r\n")
br.ReadString('\n') // Should be DATA.
fmt.Fprintf(server, "354 continue\r\n")
reader := smtp.NewDataReader(br)
io.Copy(io.Discard, reader)
fmt.Fprintf(server, "250 ok\r\n")
br.ReadString('\n') // Should be QUIT.
fmt.Fprintf(server, "221 ok\r\n")
smtpdone <- struct{}{}
}
testDeliver := func(fakeServer func(conn net.Conn)) bool {
t.Helper()
// Setting up a pipe. We'll start a fake smtp server on the server-side. And return the
// client-side to the invocation dial, for the attempted delivery from the queue.
// The delivery should succeed.
server, client := net.Pipe()
defer server.Close()
defer client.Close()
var wasNetDialer bool
dial = func(ctx context.Context, dialer contextDialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
_, wasNetDialer = dialer.(*net.Dialer)
dialed <- struct{}{}
return client, nil
}
case <-timer.C:
t.Fatalf("no dial within 1s")
waitDeliver := func() {
t.Helper()
timer.Reset(time.Second)
select {
case <-dialed:
select {
case <-smtpdone:
i := 0
for {
xmsgs, err := List(ctxbg)
tcheck(t, err, "list queue")
if len(xmsgs) == 0 {
break
}
i++
if i == 10 {
t.Fatalf("%d messages in queue, expected 0", len(xmsgs))
}
time.Sleep(100 * time.Millisecond)
}
case <-timer.C:
t.Fatalf("no deliver within 1s")
}
case <-timer.C:
t.Fatalf("no dial within 1s")
}
<-deliveryResult // Deliver sends here.
}
go fakeServer(server)
launchWork(resolver, map[string]struct{}{})
waitDeliver()
return wasNetDialer
}
// Test direct delivery.
wasNetDialer := testDeliver(fakeSMTPServer)
if !wasNetDialer {
t.Fatalf("expected net.Dialer as dialer")
}
// Add a message to be delivered with submit because of its route.
topath := smtp.Path{Localpart: "mjl", IPDomain: dns.IPDomain{Domain: dns.Domain{ASCII: "submit.example"}}}
_, err = Add(ctxbg, xlog, "mjl", path, topath, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
tcheck(t, err, "add message to queue for delivery")
wasNetDialer = testDeliver(fakeSubmitServer)
if !wasNetDialer {
t.Fatalf("expected net.Dialer as dialer")
}
// Add a message to be delivered with submit because of explicitly configured transport, that uses TLS.
msgID, err := Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
tcheck(t, err, "add message to queue for delivery")
transportSubmitTLS := "submittls"
n, err = Kick(ctxbg, msgID, "", "", &transportSubmitTLS)
tcheck(t, err, "kick queue")
if n != 1 {
t.Fatalf("kick changed %d messages, expected 1", n)
}
// Make fake cert, and make it trusted.
cert := fakeCert(t, "submission.example", false)
mox.Conf.Static.TLS.CertPool = x509.NewCertPool()
mox.Conf.Static.TLS.CertPool.AddCert(cert.Leaf)
tlsConfig := tls.Config{
Certificates: []tls.Certificate{cert},
}
wasNetDialer = testDeliver(func(conn net.Conn) {
conn = tls.Server(conn, &tlsConfig)
fakeSubmitServer(conn)
})
if !wasNetDialer {
t.Fatalf("expected net.Dialer as dialer")
}
// Add a message to be delivered with socks.
msgID, err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
tcheck(t, err, "add message to queue for delivery")
transportSocks := "socks"
n, err = Kick(ctxbg, msgID, "", "", &transportSocks)
tcheck(t, err, "kick queue")
if n != 1 {
t.Fatalf("kick changed %d messages, expected 1", n)
}
wasNetDialer = testDeliver(fakeSMTPServer)
if wasNetDialer {
t.Fatalf("expected non-net.Dialer as dialer") // SOCKS5 dialer is a private type, we cannot check for it.
}
<-deliveryResult // Deliver sends here.
// Add another message that we'll fail to deliver entirely.
err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
_, err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
tcheck(t, err, "add message to queue for delivery")
msgs, err = List(ctxbg)
@ -270,7 +369,7 @@ func TestQueue(t *testing.T) {
}()
seq := 0
dial = func(ctx context.Context, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dial = func(ctx context.Context, dialer contextDialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
seq++
switch seq {
default:
@ -337,7 +436,7 @@ func TestQueueStart(t *testing.T) {
MX: map[string][]*net.MX{"mox.example.": {{Host: "mox.example", Pref: 10}}},
}
dialed := make(chan struct{}, 1)
dial = func(ctx context.Context, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dial = func(ctx context.Context, dialer contextDialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dialed <- struct{}{}
return nil, fmt.Errorf("failure from test")
}
@ -374,7 +473,7 @@ func TestQueueStart(t *testing.T) {
}
path := smtp.Path{Localpart: "mjl", IPDomain: dns.IPDomain{Domain: dns.Domain{ASCII: "mox.example"}}}
err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
_, err = Add(ctxbg, xlog, "mjl", path, path, false, false, int64(len(testmsg)), nil, prepareFile(t), nil, true)
tcheck(t, err, "add message to queue for delivery")
checkDialed(true)
@ -383,7 +482,7 @@ func TestQueueStart(t *testing.T) {
checkDialed(false)
// Kick for real, should see another attempt.
n, err := Kick(ctxbg, 0, "mox.example", "")
n, err := Kick(ctxbg, 0, "mox.example", "", nil)
tcheck(t, err, "kick queue")
if n != 1 {
t.Fatalf("kick changed %d messages, expected 1", n)
@ -520,7 +619,7 @@ func TestDialHost(t *testing.T) {
},
}
dial = func(ctx context.Context, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
dial = func(ctx context.Context, dialer contextDialer, timeout time.Duration, addr string, laddr net.Addr) (net.Conn, error) {
return nil, nil // No error, nil connection isn't used.
}
@ -529,12 +628,44 @@ func TestDialHost(t *testing.T) {
}
m := Msg{DialedIPs: map[string][]net.IP{}}
_, ip, dualstack, err := dialHost(ctxbg, xlog, resolver, ipdomain("dualstack.example"), &m)
_, ip, dualstack, err := dialHost(ctxbg, xlog, resolver, nil, ipdomain("dualstack.example"), 25, &m)
if err != nil || ip.String() != "10.0.0.1" || !dualstack {
t.Fatalf("expected err nil, address 10.0.0.1, dualstack true, got %v %v %v", err, ip, dualstack)
}
_, ip, dualstack, err = dialHost(ctxbg, xlog, resolver, ipdomain("dualstack.example"), &m)
_, ip, dualstack, err = dialHost(ctxbg, xlog, resolver, nil, ipdomain("dualstack.example"), 25, &m)
if err != nil || ip.String() != "2001:db8::1" || !dualstack {
t.Fatalf("expected err nil, address 2001:db8::1, dualstack true, got %v %v %v", err, ip, dualstack)
}
}
// Just a cert that appears valid.
func fakeCert(t *testing.T, name string, expired bool) tls.Certificate {
notAfter := time.Now()
if expired {
notAfter = notAfter.Add(-time.Hour)
} else {
notAfter = notAfter.Add(time.Hour)
}
privKey := ed25519.NewKeyFromSeed(make([]byte, ed25519.SeedSize)) // Fake key, don't use this for real!
template := &x509.Certificate{
SerialNumber: big.NewInt(1), // Required field...
DNSNames: []string{name},
NotBefore: time.Now().Add(-time.Hour),
NotAfter: notAfter,
}
localCertBuf, err := x509.CreateCertificate(cryptorand.Reader, template, template, privKey.Public(), privKey)
if err != nil {
t.Fatalf("making certificate: %s", err)
}
cert, err := x509.ParseCertificate(localCertBuf)
if err != nil {
t.Fatalf("parsing generated certificate: %s", err)
}
c := tls.Certificate{
Certificate: [][]byte{localCertBuf},
PrivateKey: privKey,
Leaf: cert,
}
return c
}