From 3484651691cb3a78062e5c19d5ac7046a5dfba7b Mon Sep 17 00:00:00 2001
From: Laurent Meunier <laurent@deltalima.net>
Date: Thu, 28 Mar 2024 17:47:11 +0100
Subject: [PATCH] do not require the SMTPUTF8 extension when not needed
fix #145
---
smtpserver/server.go | 31 +++++++++++++++++++++++-
smtpserver/server_test.go | 50 +++++++++++++++++++++++++++++++++++++++
2 files changed, 80 insertions(+), 1 deletion(-)
diff --git a/smtpserver/server.go b/smtpserver/server.go
index 6477020..6bd8dfa 100644
--- a/smtpserver/server.go
+++ b/smtpserver/server.go
@@ -26,6 +26,7 @@ import (
"strings"
"sync"
"time"
+ "unicode"
"golang.org/x/exp/maps"
"golang.org/x/text/unicode/norm"
@@ -331,7 +332,7 @@ type conn struct {
futureRelease time.Time // MAIL FROM with HOLDFOR or HOLDUNTIL.
futureReleaseRequest string // For use in DSNs, either "for;" or "until;" plus original value. ../rfc/4865:305
has8bitmime bool // If MAIL FROM parameter BODY=8BITMIME was sent. Required for SMTPUTF8.
- smtputf8 bool // todo future: we should keep track of this per recipient. perhaps only a specific recipient requires smtputf8, e.g. due to a utf8 localpart. we should decide ourselves if the message needs smtputf8, e.g. due to utf8 header values.
+ smtputf8 bool // todo future: we should keep track of this per recipient. perhaps only a specific recipient requires smtputf8, e.g. due to a utf8 localpart.
recipients []rcptAccount
}
@@ -1899,6 +1900,34 @@ func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWr
xsmtpUserErrorf(smtp.C550MailboxUnavail, smtp.SePol7DeliveryUnauth1, "must match authenticated user")
}
+ // Check if the message contains non-ascii characters. If no such characters are found,
+ // the SMTPUTF8 extension is not required.
+ // ../rfc/6531:497
+ isASCII := func(s string) bool {
+ for _, c := range s {
+ if c > unicode.MaxASCII {
+ return false
+ }
+ }
+ return true
+ }
+ c.smtputf8 = !isASCII(c.mailFrom.Localpart.String())
+ for _, rcpt := range c.recipients {
+ if !isASCII(rcpt.rcptTo.Localpart.String()) {
+ c.smtputf8 = true
+ break
+ }
+ }
+ for _, values := range header {
+ for _, value := range values {
+ if !isASCII(value) {
+ c.smtputf8 = true
+ break
+ }
+ }
+
+ }
+
// TLS-Required: No header makes us not enforce recipient domain's TLS policy.
// ../rfc/8689:206
// Only when requiretls smtp extension wasn't used. ../rfc/8689:246
diff --git a/smtpserver/server_test.go b/smtpserver/server_test.go
index d49df9d..eacc691 100644
--- a/smtpserver/server_test.go
+++ b/smtpserver/server_test.go
@@ -1767,3 +1767,53 @@ func TestFutureRelease(t *testing.T) {
test(" HOLDFOR=1 HOLDFOR=1", "501") // Duplicate.
test(" HOLDFOR=1 HOLDUNTIL="+time.Now().Add(time.Hour).UTC().Format(time.RFC3339), "501") // Duplicate.
}
+
+// Test SMTPUTF8
+func TestSMTPUTF8(t *testing.T) {
+ ts := newTestServer(t, filepath.FromSlash("../testdata/smtp/mox.conf"), dns.MockResolver{})
+ defer ts.close()
+
+ ts.user = "mjl@mox.example"
+ ts.pass = password0
+ ts.submission = true
+
+ test := func(mailFrom string, rcptTo string, headerValue string, clientSmtputf8 bool, expectedSmtputf8 bool, expErr *smtpclient.Error) {
+ t.Helper()
+
+ ts.run(func(_ error, client *smtpclient.Client) {
+ t.Helper()
+ msg := strings.ReplaceAll(fmt.Sprintf(`From: <%s>
+To: <%s>
+Subject: test
+X-Custom-Test-Header: %s
+
+test email
+`, mailFrom, rcptTo, headerValue), "\n", "\r\n")
+
+ err := client.Deliver(ctxbg, mailFrom, rcptTo, int64(len(msg)), strings.NewReader(msg), false, clientSmtputf8, false)
+ var cerr smtpclient.Error
+ if expErr == nil && err != nil || expErr != nil && (err == nil || !errors.As(err, &cerr) || cerr.Code != expErr.Code || cerr.Secode != expErr.Secode) {
+ t.Fatalf("got err %#v, expected %#v", err, expErr)
+ }
+ if err != nil {
+ return
+ }
+
+ msgs, _ := queue.List(ctxbg, queue.Filter{})
+ queuedMsg := msgs[len(msgs)-1]
+ if queuedMsg.SMTPUTF8 != expectedSmtputf8 {
+ t.Fatalf("[%s / %s / %s] got SMTPUTF8 %t, expected %t", mailFrom, rcptTo, headerValue, queuedMsg.SMTPUTF8, expectedSmtputf8)
+ }
+ })
+ }
+
+ test(`mjl@mox.example`, `remote@example.org`, "ascii", false, false, nil)
+ test(`mjl@mox.example`, `remote@example.org`, "ascii", true, false, nil)
+ test(`mjl@mox.example`, `🙂@example.org`, "ascii", true, true, nil)
+ test(`mjl@mox.example`, `🙂@example.org`, "ascii", false, true, &smtpclient.Error{Permanent: true, Code: smtp.C553BadMailbox, Secode: smtp.SeMsg6NonASCIIAddrNotPermitted7})
+ test(`Ω@mox.example`, `remote@example.org`, "ascii", true, true, nil)
+ test(`Ω@mox.example`, `remote@example.org`, "ascii", false, true, &smtpclient.Error{Permanent: true, Code: smtp.C550MailboxUnavail, Secode: smtp.SeMsg6NonASCIIAddrNotPermitted7})
+ test(`mjl@mox.example`, `remote@example.org`, "non-ascii-😍", false, true, nil)
+ test(`mjl@mox.example`, `remote@example.org`, "non-ascii-😍", true, true, nil)
+ test(`Ω@mox.example`, `🙂@example.org`, "non-ascii-😍", true, true, nil)
+}