smtpclient.c: use client_bind_name or servername as EHLO hostname

cyrusimap · Jul 24, 2024 · 400346f · 400346f
1 parent 7c2ba7c
commit 400346f
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Showing 4 changed files with 53 additions and 4 deletions.
diff --git a/cassandane/Cassandane/Instance.pm b/cassandane/Cassandane/Instance.pm
@@ -733,6 +733,11 @@ sub _generate_imapd_conf
                 smtp_backend => 'host',
                 smtp_host => $self->{smtphost},
             );
+            if (not defined $config->get("servername")) {
+                # smtpclient needs client_bind_name or servername,
+                # falls back to servername if client_bind isn't set.
+                $config->set(servername => "127.0.0.1");
+            }
         }
     }
     else {

diff --git a/cassandane/Cassandane/Net/SMTPServer.pm b/cassandane/Cassandane/Net/SMTPServer.pm
@@ -54,8 +54,8 @@ sub new_connection {
 }
 
 sub helo {
-    my ($Self) = @_;
-    $Self->mylog("SMTP: HELO");
+    my ($Self, $Host) = @_;
+    $Self->mylog("SMTP: HELO $Host");
     return if $Self->override('helo');
     $Self->send_client_resp(250, "localhost",
                             "AUTH", "DSN", "SIZE 10000", "ENHANCEDSTATUSCODES");

diff --git a/changes/next/smtpclient_ehlo_hostname b/changes/next/smtpclient_ehlo_hostname
@@ -0,0 +1,16 @@
+Description:
+
+Changes the SMTP client EHLO hostname from "localhost" to the `client_bind_name` config option, if set and enabled, or `servername` otherwise.
+
+
+Config changes:
+
+None
+
+Upgrade instructions:
+
+None
+
+GitHub issue:
+
+4960
diff --git a/imap/smtpclient.c b/imap/smtpclient.c
@@ -102,10 +102,13 @@ enum {
     SMTPCLIENT_CAPA_JMAPID    = (1 << 10),
 };
 
+static const char *smtpclient_ehlo_hostname = NULL;
+
 static struct protocol_t smtp_protocol =
 { "smtp", "smtp", TYPE_STD,
   { { { 0, "220 " },
-      { "EHLO", "localhost", "250 ", NULL,
+        // EHLO hostname will be set in smtpclient_open().
+      { "EHLO", NULL, "250 ", NULL,
         CAPAF_ONE_PER_LINE|CAPAF_SKIP_FIRST_WORD|CAPAF_DASH_STUFFING,
         { { "AUTH", CAPA_AUTH },
           { "STARTTLS", CAPA_STARTTLS },
@@ -143,6 +146,31 @@ static void smtpclient_logerror(smtpclient_t *sm, const char *cmd, int r);
 
 EXPORTED int smtpclient_open(smtpclient_t **smp)
 {
+    if (!smtpclient_ehlo_hostname) {
+        if (config_getswitch(IMAPOPT_CLIENT_BIND)) {
+            smtpclient_ehlo_hostname =
+                config_getstring(IMAPOPT_CLIENT_BIND_NAME);
+        }
+        if (!smtpclient_ehlo_hostname) {
+            smtpclient_ehlo_hostname = config_getstring(IMAPOPT_SERVERNAME);
+        }
+        if (!smtpclient_ehlo_hostname) {
+            xsyslog(LOG_ERR,
+                    "can not determine EHLO hostname, "
+                    "either client_bind/client_bind_name or servername option must be set",
+                    NULL);
+            return IMAP_INTERNAL;
+        }
+        if (smtp_protocol.type == TYPE_STD &&
+            !strcasecmpsafe(smtp_protocol.u.std.capa_cmd.cmd, "EHLO")) {
+            smtp_protocol.u.std.capa_cmd.arg = smtpclient_ehlo_hostname;
+        }
+        else {
+            xsyslog(LOG_ERR, "unexpected smtp_protocol value", NULL);
+            return IMAP_INTERNAL;
+        }
+    }
+
     int r = 0;
     const char *backend = config_getstring(IMAPOPT_SMTP_BACKEND);
 
@@ -366,7 +394,7 @@ static int smtpclient_ehlo(smtpclient_t *sm)
     int r = 0;
 
     /* Say EHLO */
-    buf_setcstr(&sm->buf, "EHLO localhost\r\n");
+    buf_printf(&sm->buf, "EHLO %s\r\n", smtpclient_ehlo_hostname);
     r = smtpclient_writebuf(sm, &sm->buf, 1);
     if (r) goto done;
     buf_reset(&sm->buf);