From fcc5097d0e8e6a5f2245f0736769710ed902ef63 Mon Sep 17 00:00:00 2001
From: Mario Fetka <mario.fetka@gmail.com>
Date: Sun, 26 Jul 2026 22:53:10 +0200
Subject: [PATCH] Report relayhost preparation failures

---
 src/agents/smtp/smtpc.c | 46 +++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/agents/smtp/smtpc.c b/src/agents/smtp/smtpc.c
index a6a0efa..74073a9 100755
--- a/src/agents/smtp/smtpc.c
+++ b/src/agents/smtp/smtpc.c
@@ -864,6 +864,7 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
     CURLcode code = CURLE_FAILED_INIT;
     long response = 0;
     BOOL success = FALSE;
+    BongoMailAuthStatus senderStatus;
 
     recipient->Result = DELIVER_TRY_LATER;
     if (route == NULL || route->host == NULL || route->host[0] == '\0' ||
@@ -877,13 +878,26 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
          strcmp(route->tlsSecurityLevel, "none") == 0) ||
         strpbrk(route->host, "/?#@\r\n") != NULL ||
         ((route->username == NULL || route->username[0] == '\0') !=
-         (route->password == NULL || route->password[0] == '\0')) ||
-        GetEnvelopeSender(queue, rewrittenSender, sizeof(rewrittenSender),
-                          &envelopeSender) != BONGO_MAILAUTH_OK) goto done;
+         (route->password == NULL || route->password[0] == '\0'))) {
+        Log(LOG_ERROR, "Invalid relay route for message %s",
+            queue != NULL && queue->qID != NULL ? queue->qID : "(unknown)");
+        goto done;
+    }
+    senderStatus = GetEnvelopeSender(
+        queue, rewrittenSender, sizeof(rewrittenSender), &envelopeSender);
+    if (senderStatus != BONGO_MAILAUTH_OK) {
+        Log(LOG_ERROR,
+            "Cannot prepare relay envelope sender for message %s (status %d)",
+            queue->qID, (int)senderStatus);
+        goto done;
+    }
     if (!BongoMailboxDomainToASCII(
             envelopeSender, canonicalSender, sizeof(canonicalSender)) ||
         !BongoMailboxDomainToASCII(
             recipient->To, canonicalRecipient, sizeof(canonicalRecipient))) {
+        Log(LOG_ERROR,
+            "Cannot canonicalize relay envelope for message %s to %s",
+            queue->qID, recipient->To);
         recipient->Result = DELIVER_FAILURE;
         goto done;
     }
@@ -894,6 +908,8 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
     if (requiresSMTPUTF8 &&
         (!SMTPStringIsValidUTF8(envelopeSender) ||
          !SMTPStringIsValidUTF8(canonicalRecipient))) {
+        Log(LOG_ERROR, "Invalid UTF-8 relay envelope for message %s",
+            queue->qID);
         recipient->Result = DELIVER_FAILURE;
         goto done;
     }
@@ -907,6 +923,8 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
             (requiresSMTPUTF8 || (queue->flags & MSG_FLAG_ENCODING_8BITM))
                 ? " BODY=8BITMIME" : "");
         if (written < 0 || (size_t) written >= sizeof(curlMailFrom)) {
+            Log(LOG_ERROR, "Relay MAIL FROM is too long for message %s",
+                queue->qID);
             recipient->Result = DELIVER_FAILURE;
             goto done;
         }
@@ -914,12 +932,28 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
     }
     if (snprintf(url, sizeof(url), "%s://%s:%d",
                  route->tlsWrapperMode ? "smtps" : "smtp",
-                 route->host, route->port) >= (int) sizeof(url)) goto done;
+                 route->host, route->port) >= (int) sizeof(url)) {
+        Log(LOG_ERROR, "Relay URL is too long for message %s", queue->qID);
+        goto done;
+    }
     message = tmpfile();
-    if (message == NULL || QueueMessageToFile(queue, message, &messageSize) != 0) goto done;
+    if (message == NULL) {
+        Log(LOG_ERROR, "Cannot allocate relay message file for queue %s",
+            queue->qID);
+        goto done;
+    }
+    if (QueueMessageToFile(queue, message, &messageSize) != 0) {
+        Log(LOG_ERROR, "Cannot retrieve relay message body for queue %s",
+            queue->qID);
+        goto done;
+    }
     curl = curl_easy_init();
     recipients = curl_slist_append(recipients, canonicalRecipient);
-    if (curl == NULL || recipients == NULL) goto done;
+    if (curl == NULL || recipients == NULL) {
+        Log(LOG_ERROR, "Cannot initialize relay transport for queue %s",
+            queue->qID);
+        goto done;
+    }
     curl_easy_setopt(curl, CURLOPT_URL, url);
     if (route->username != NULL && route->username[0] != '\0') {
         curl_easy_setopt(curl, CURLOPT_USERNAME, route->username);