[PATCH 2 of 2] Mail: fixed "upstream: ..." in logs with "smtp_auth none"

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1755187434 -10800
#      Thu Aug 14 19:03:54 2025 +0300
# Node ID 31ecd4a1b346b117e84128988bd7bf056e7aa3b9
# Parent  13ee0b2ffee6d852bc5aa4e10fcf217a982c8e79
Mail: fixed "upstream: ..." in logs with "smtp_auth none".

Previously, it was not added to the log line due to no s->login, which
caused early return from the function.  Fix is to restructure the log handler
to use "if (...)" blocks instead, similarly to ngx_http_log_error_handler().

diff --git a/src/mail/ngx_mail_handler.c b/src/mail/ngx_mail_handler.c
--- a/src/mail/ngx_mail_handler.c
+++ b/src/mail/ngx_mail_handler.c
@@ -1486,19 +1486,15 @@ ngx_mail_log_error(ngx_log_t *log, u_cha
     len -= p - buf;
     buf = p;
 
-    if (s->login.len == 0) {
-        return p;
+    if (s->login.len) {
+        p = ngx_snprintf(buf, len, ", login: \"%V\"", &s->login);
+        len -= p - buf;
+        buf = p;
     }
 
-    p = ngx_snprintf(buf, len, ", login: \"%V\"", &s->login);
-    len -= p - buf;
-    buf = p;
-
-    if (s->proxy == NULL) {
-        return p;
+    if (s->proxy) {
+        p = ngx_snprintf(buf, len, ", upstream: %V", s->proxy->upstream.name);
     }
 
-    p = ngx_snprintf(buf, len, ", upstream: %V", s->proxy->upstream.name);
-
     return p;
 }