package courier
import (
"encoding/json"
"errors"
"fmt"
"net"
"os"
"strings"
"testing"
"time"
"blitiri.com.ar/go/chasquid/internal/domaininfo"
"blitiri.com.ar/go/chasquid/internal/sts"
"blitiri.com.ar/go/chasquid/internal/trace"
)
// This domain will cause idna.ToASCII to fail.
var invalidDomain = "test " + strings.Repeat("x", 65536) + "\uff00"
// Override the netLookupMX function, to return controlled results for
// testing.
var testMX = map[string][]*net.MX{}
var testMXErr = map[string]error{}
func init() {
netLookupMX = func(name string) ([]*net.MX, error) {
return testMX[name], testMXErr[name]
}
}
func newSMTP(t *testing.T) *SMTP {
dinfo, err := domaininfo.New(t.ArtifactDir())
if err != nil {
t.Fatal(err)
}
return &SMTP{"hello", dinfo, nil}
}
func TestSMTP(t *testing.T) {
// Shorten the total timeout, so the test fails quickly if the protocol
// gets stuck.
smtpTotalTimeout = 5 * time.Second
responses := map[string]string{
"_welcome": "220 welcome\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "354 send data\n",
"_DATA": "250 data ok\n",
"QUIT": "250 quit ok\n",
}
srv := newFakeServer(t, responses, 1)
host, port := srv.HostPort()
// Put a non-existing host first, so we check that if the first host
// doesn't work, we try with the rest.
// The host we use is invalid, to avoid having to do an actual network
// lookup which makes the test more hermetic. This is a hack, ideally we
// would be able to override the default resolver, but Go does not
// implement that yet.
testMX["to"] = []*net.MX{
{Host: ":::", Pref: 10},
{Host: host, Pref: 20},
}
*smtpPort = port
s := newSMTP(t)
err, _ := s.Deliver("me@me", "to@to", []byte("data"))
if err != nil {
t.Errorf("deliver failed: %v", err)
}
srv.Wait()
}
func TestSMTPErrors(t *testing.T) {
// Shorten the total timeout, so the test fails quickly if the protocol
// gets stuck.
smtpTotalTimeout = 1 * time.Second
cases := []struct {
responses map[string]string
wantErr string
}{
// First test: hang response, should fail due to timeout.
// Which step times out depends on timing, so just check that the
// error mentions the server.
{map[string]string{
"_welcome": "220 no newline",
}, ""},
// Server rejects us in the greeting.
{map[string]string{
"_welcome": "554 go away\n",
}, "greeting failed: 554 "},
// MAIL FROM not allowed.
{map[string]string{
"_welcome": "220 mail from not allowed\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "501 mail error\n",
}, "MAIL/RCPT failed: 501 "},
// RCPT TO not allowed.
{map[string]string{
"_welcome": "220 rcpt to not allowed\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "501 rcpt error\n",
}, "MAIL/RCPT failed: 501 "},
// DATA error.
{map[string]string{
"_welcome": "220 data error\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "554 data error\n",
}, "DATA failed: 554 "},
// DATA response error.
{map[string]string{
"_welcome": "220 data response error\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "354 send data\n",
"_DATA": "551 data response error\n",
}, "message not accepted: 551 "},
}
for _, c := range cases {
srv := newFakeServer(t, c.responses, 1)
host, port := srv.HostPort()
testMX["to"] = []*net.MX{{Host: host, Pref: 10}}
*smtpPort = port
s := newSMTP(t)
err, _ := s.Deliver("me@me", "to@to", []byte("data"))
want := host + ": " + c.wantErr
if err == nil || !strings.Contains(err.Error(), want) {
t.Errorf("case %q: expected error containing %q, got %v",
c.responses["_welcome"], want, err)
}
t.Logf("failed as expected: %v", err)
srv.Wait()
}
}
func TestSMTPForward(t *testing.T) {
// Shorten the total timeout, so the test fails quickly if the protocol
// gets stuck.
smtpTotalTimeout = 5 * time.Second
responses := map[string]string{
"_welcome": "220 welcome\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "354 send data\n",
"_DATA": "250 data ok\n",
"QUIT": "250 quit ok\n",
}
srv := newFakeServer(t, responses, 1)
host, port := srv.HostPort()
*smtpPort = port
s := newSMTP(t)
// Successful forward. The first server is invalid (see TestSMTP), so we
// also check that we try the next one.
err, _ := s.Forward("me@me", "to@to", []byte("data"),
[]string{":::", host})
if err != nil {
t.Errorf("forward failed: %v", err)
}
srv.Wait()
// All servers fail with transient errors.
err, permanent := s.Forward("me@me", "to@to", []byte("data"),
[]string{":::"})
want := "all servers failed temporarily, last error: :::: "
if err == nil || !strings.HasPrefix(err.Error(), want) || permanent {
t.Errorf("expected transient error starting with %q, got %v (%v)",
want, err, permanent)
}
// Permanent failure: we return right away.
responses["RCPT TO:<to@to>"] = "550 rcpt error\n"
srv = newFakeServer(t, responses, 1)
host, port = srv.HostPort()
*smtpPort = port
err, permanent = s.Forward("me@me", "to@to", []byte("data"),
[]string{host})
want = host + ": MAIL/RCPT failed: 550 "
if err == nil || !strings.HasPrefix(err.Error(), want) || !permanent {
t.Errorf("expected permanent error starting with %q, got %v (%v)",
want, err, permanent)
}
srv.Wait()
// No servers to forward to.
err, permanent = s.Forward("me@me", "to@to", []byte("data"), nil)
if err == nil || err.Error() != "no servers to forward to" || permanent {
t.Errorf("expected transient 'no servers' error, got %v (%v)",
err, permanent)
}
}
// Test delivery to a domain whose MTA-STS policy doesn't allow any of its
// MXs.
func TestSTSNoMXAllowed(t *testing.T) {
testMX["sts-none"] = []*net.MX{
{Host: "mx1", Pref: 10},
{Host: "mx2", Pref: 20},
}
t.Cleanup(func() { delete(testMX, "sts-none") })
// Put the policy in the cache directly, so we don't need to fetch it.
// This mimics the cache's on-disk format: the policy as JSON in a
// "pol:<domain>" file, with the expiration time as its modification time.
dir := t.ArtifactDir()
policy := &sts.Policy{
Version: "STSv1",
Mode: sts.Enforce,
MXs: []string{"other-mx"},
MaxAge: 1 * time.Hour,
}
data, err := json.Marshal(policy)
if err != nil {
t.Fatal(err)
}
fname := dir + "/pol:sts-none"
if err := os.WriteFile(fname, data, 0640); err != nil {
t.Fatal(err)
}
expires := time.Now().Add(policy.MaxAge)
if err := os.Chtimes(fname, expires, expires); err != nil {
t.Fatal(err)
}
stsCache, err := sts.NewCache(dir)
if err != nil {
t.Fatal(err)
}
s := newSMTP(t)
s.STSCache = stsCache
err, permanent := s.Deliver("me@me", "to@sts-none", []byte("data"))
want := `none of the mail servers for "sts-none" are allowed by its ` +
`MTA-STS policy`
if err == nil || err.Error() != want {
t.Errorf("expected error %q, got %v", want, err)
}
if permanent {
t.Errorf("expected transient failure, got permanent")
}
}
func TestDeliverInvalidDomain(t *testing.T) {
// Mimic what the real resolver returns for invalid domains, so delivery
// would fall back to A if we didn't check the domain.
testMXErr["a/b"] = &net.DNSError{
Err: "no such host (test)",
IsNotFound: true,
}
t.Cleanup(func() { delete(testMXErr, "a/b") })
// Set up an STS cache, as that is one of the things that can't handle
// invalid domains.
stsCache, err := sts.NewCache(t.ArtifactDir())
if err != nil {
t.Fatal(err)
}
s := newSMTP(t)
s.STSCache = stsCache
err, permanent := s.Deliver("me@me", "to@a/b", []byte("data"))
if err == nil {
t.Errorf("expected error, got nil")
}
if !permanent {
t.Errorf("expected permanent failure, got transient")
}
}
func TestNoMXServer(t *testing.T) {
testMX["to"] = []*net.MX{}
s := newSMTP(t)
err, permanent := s.Deliver("me@me", "to@to", []byte("data"))
if err == nil {
t.Errorf("delivery worked, expected failure")
}
if !permanent {
t.Errorf("expected permanent failure, got transient (%v)", err)
}
if want := `no mail servers found for "to"`; err.Error() != want {
t.Errorf("expected error %q, got %q", want, err)
}
}
func TestDeliverMXLookupError(t *testing.T) {
dnsErr := &net.DNSError{
Err: "temp error (test)",
Name: "lookuperr",
IsTemporary: true,
}
testMXErr["lookuperr"] = dnsErr
t.Cleanup(func() { delete(testMXErr, "lookuperr") })
s := newSMTP(t)
err, permanent := s.Deliver("me@me", "to@lookuperr", []byte("data"))
want := `error looking up mail servers for "lookuperr": ` +
`lookup lookuperr: temp error (test)`
if err == nil || err.Error() != want {
t.Errorf("expected error %q, got %v", want, err)
}
if !errors.Is(err, dnsErr) {
t.Errorf("expected error to wrap the DNS error, got %v", err)
}
if permanent {
t.Errorf("expected transient failure, got permanent")
}
}
func TestTooManyMX(t *testing.T) {
tr := trace.New("test", "test")
testMX["domain"] = []*net.MX{
{Host: "h1", Pref: 10}, {Host: "h2", Pref: 20},
{Host: "h3", Pref: 30}, {Host: "h4", Pref: 40},
{Host: "h5", Pref: 50}, {Host: "h5", Pref: 60},
}
mxs, err, perm := lookupMXs(tr, "domain")
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if perm != true {
t.Fatalf("expected perm == true")
}
if len(mxs) != 5 {
t.Errorf("expected len(mxs) == 5, got: %v", mxs)
}
}
func TestFallbackToA(t *testing.T) {
tr := trace.New("test", "test")
testMX["domain"] = nil
testMXErr["domain"] = &net.DNSError{
Err: "no such host (test)",
IsTemporary: false,
IsNotFound: true,
}
mxs, err, perm := lookupMXs(tr, "domain")
if err != nil {
t.Errorf("unexpected error: %v", err)
}
if perm != true {
t.Errorf("expected perm == true")
}
if !(len(mxs) == 1 && mxs[0] == "domain") {
t.Errorf("expected mxs == [domain], got: %v", mxs)
}
}
func TestTemporaryDNSerror(t *testing.T) {
tr := trace.New("test", "test")
testMX["domain"] = nil
testMXErr["domain"] = &net.DNSError{
Err: "temp error (test)",
IsTemporary: true,
}
mxs, err, perm := lookupMXs(tr, "domain")
if !(mxs == nil && err == testMXErr["domain"]) {
t.Errorf("expected mxs == nil, err == test error, got: %v, %v", mxs, err)
}
if perm != false {
t.Errorf("expected perm == false")
}
}
func TestMXLookupError(t *testing.T) {
tr := trace.New("test", "test")
testMX["domain"] = nil
testMXErr["domain"] = fmt.Errorf("test error")
mxs, err, perm := lookupMXs(tr, "domain")
if !(mxs == nil && err == testMXErr["domain"]) {
t.Errorf("expected mxs == nil, err == test error, got: %v, %v", mxs, err)
}
if perm != false {
t.Errorf("expected perm == false")
}
}
func TestLookupInvalidDomain(t *testing.T) {
tr := trace.New("test", "test")
mxs, err, perm := lookupMXs(tr, invalidDomain)
if !(mxs == nil && err != nil) {
t.Errorf("expected err != nil, got: %v, %v", mxs, err)
}
if perm != true {
t.Fatalf("expected perm == true")
}
}
// Server fake responses for a complete TLS delivery.
// We use this in a few tests, so make it common.
var tlsResponses = map[string]string{
"_welcome": "220 welcome\n",
"EHLO hello": "250-ehlo ok\n250 STARTTLS\n",
"STARTTLS": "220 starttls go\n",
"_STARTTLS": "ok",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "354 send data\n",
"_DATA": "250 data ok\n",
"QUIT": "250 quit ok\n",
}
func TestTLS(t *testing.T) {
smtpTotalTimeout = 5 * time.Second
srv := newFakeServer(t, tlsResponses, 1)
_, *smtpPort = srv.HostPort()
testMX["to"] = []*net.MX{
{Host: "localhost", Pref: 20},
}
s := newSMTP(t)
err, _ := s.Deliver("me@me", "to@to", []byte("data"))
if err != nil {
t.Errorf("deliver failed: %v", err)
}
srv.Wait()
// Now do another delivery, but without TLS, to check that the detection
// of connection downgrade is working.
responses := map[string]string{
"_welcome": "220 welcome\n",
"EHLO hello": "250 ehlo ok\n",
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "354 send data\n",
"_DATA": "250 data ok\n",
"QUIT": "250 quit ok\n",
}
srv = newFakeServer(t, responses, 1)
_, *smtpPort = srv.HostPort()
err, permanent := s.Deliver("me@me", "to@to", []byte("data"))
if !strings.Contains(err.Error(),
"security level check failed: connection is PLAIN") {
t.Errorf("expected sec level check failed, got: %v", err)
}
if permanent != false {
t.Errorf("expected transient failure, got permanent")
}
srv.Wait()
}
func TestTLSError(t *testing.T) {
smtpTotalTimeout = 5 * time.Second
responses := map[string]string{
"_welcome": "220 welcome\n",
// STARTTLS should be advertised so we try to initiate it.
"EHLO hello": "250-ehlo ok\n250 STARTTLS\n",
// Error in STARTTLS request. Note that a TLS-layer error also falls
// under this code path, so both situations are covered by this test.
"STARTTLS": "500 starttls err\n",
"_STARTTLS": "no",
// Rest of the transaction is normal and straightforward.
"MAIL FROM:<me@me>": "250 mail ok\n",
"RCPT TO:<to@to>": "250 rcpt ok\n",
"DATA": "354 send data\n",
"_DATA": "250 data ok\n",
"QUIT": "250 quit ok\n",
}
// Note we expect 2 connections to the fake server (because of the retry
// after the failed STARTTLS). Note this also checks that we correctly
// close the errored connection, instead of leaving it lingering.
srv := newFakeServer(t, responses, 2)
_, *smtpPort = srv.HostPort()
testMX["to"] = []*net.MX{
{Host: "localhost", Pref: 20},
}
s := newSMTP(t)
err, _ := s.Deliver("me@me", "to@to", []byte("data"))
if err != nil {
t.Errorf("deliver failed: %v", err)
}
// Double check that we delivered over a plaintext connection.
tr := trace.New("test", "test")
defer tr.Finish()
if !s.Dinfo.OutgoingSecLevel(tr, "to", domaininfo.SecLevel_PLAIN) {
t.Errorf("delivery did not took place over plaintext as expected")
}
srv.Wait()
}
func TestSTSPolicyEnforcement(t *testing.T) {
smtpTotalTimeout = 5 * time.Second
srv := newFakeServer(t, tlsResponses, 1)
_, *smtpPort = srv.HostPort()
s := newSMTP(t)
a := &attempt{
courier: s,
from: "me@me",
to: "to@to",
toDomain: "to",
data: []byte("data"),
tr: trace.New("test", "test"),
}
a.stsPolicy = &sts.Policy{
Version: "STSv1",
Mode: sts.Enforce,
MXs: []string{"mx"},
MaxAge: 1 * time.Minute,
}
// At this point the cert is not valid, which is incompatible with STS
// policy, so we expect it to fail.
err, permanent := a.deliver("localhost")
if !strings.Contains(err.Error(),
"connection is TLS_INSECURE, but the MTA-STS policy") {
t.Errorf("expected invalid sec level error, got %v", err)
}
if permanent != false {
t.Errorf("expected transient error, got permanent")
}
srv.Wait()
// Do another delivery attempt, but this time we trust the server cert.
// This time it should be successful, because the connection level should
// be TLS_SECURE which is required by the STS policy.
srv = newFakeServer(t, tlsResponses, 1)
_, *smtpPort = srv.HostPort()
certRoots = srv.rootCA()
defer func() {
certRoots = nil
}()
err, permanent = a.deliver("localhost")
if err != nil {
t.Errorf("expected success, got %v (permanent=%v)", err, permanent)
}
srv.Wait()
}