smtp: retain enhanced relay failure status

src/agents/smtp/protocol.c

@@ -26,6 +26,8 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <nmap.h>
+
 typedef struct {
     const char *name;
     SMTPCommand command;
@@ -793,6 +795,44 @@ SMTPFormatDsnRcptOptions(int notify_explicit,
     return 1;
 }
 
+int
+SMTPDeliveryResultFromReply(unsigned int reply_code,
+                            const char *reply_text)
+{
+    const char *enhanced = reply_text;
+
+    if (reply_code / 100U == 2U) return DELIVER_SUCCESS;
+    if (reply_code / 100U == 4U) return DELIVER_TRY_LATER;
+    if (reply_code / 100U != 5U) return DELIVER_TRY_LATER;
+    if (enhanced == NULL) return DELIVER_FAILURE;
+    if (isdigit((unsigned char)enhanced[0]) &&
+        isdigit((unsigned char)enhanced[1]) &&
+        isdigit((unsigned char)enhanced[2]) &&
+        (enhanced[3] == ' ' || enhanced[3] == '-'))
+        enhanced += 4;
+    while (*enhanced == ' ' || *enhanced == '\t') enhanced++;
+    if (enhanced[0] != '5' || enhanced[1] != '.' ||
+        !isdigit((unsigned char)enhanced[2]) || enhanced[3] != '.' ||
+        !isdigit((unsigned char)enhanced[4]))
+        return DELIVER_FAILURE;
+    if (enhanced[2] == '1' && enhanced[4] == '1')
+        return DELIVER_USER_UNKNOWN;
+    if (enhanced[2] == '1' && enhanced[4] == '3')
+        return DELIVER_BOGUS_NAME;
+    if (enhanced[2] == '2' && enhanced[4] == '2')
+        return DELIVER_QUOTA_EXCEEDED;
+    if (enhanced[2] == '4' && enhanced[4] == '1')
+        return DELIVER_REFUSED;
+    if (enhanced[2] == '4' && enhanced[4] == '4')
+        return DELIVER_HOST_UNKNOWN;
+    if (enhanced[2] == '4' && enhanced[4] == '6')
+        return DELIVER_HOPCOUNT_EXCEEDED;
+    if (enhanced[2] == '4' && enhanced[4] == '7')
+        return DELIVER_TIMEOUT;
+    if (enhanced[2] == '7') return DELIVER_BLOCKED;
+    return DELIVER_FAILURE;
+}
+
 static int
 OrcptValid(const char *value, size_t length, int smtp_utf8)
 {

src/agents/smtp/protocol.h

@@ -115,6 +115,8 @@ int SMTPFormatDsnRcptOptions(int notify_explicit,
                              const char *original_recipient,
                              int smtp_utf8, char *options,
                              size_t options_size);
+int SMTPDeliveryResultFromReply(unsigned int reply_code,
+                                const char *reply_text);
 int SMTPRequireTlsHasAuthenticatedPolicy(int mx_dnssec_authenticated,
                                          int dane_authenticated,
                                          int mta_sts_enforced,

src/agents/smtp/smtpc.c

@@ -23,6 +23,7 @@
 
 #include <config.h>
 
+#include <ctype.h>
 #include <fcntl.h>
 #include <inttypes.h>
 #include <sys/stat.h>
@@ -908,6 +909,34 @@ FormatDsnOptions(const SMTPClient *queue, const RecipStruct *recipient,
                rcpt_options, rcpt_options_size);
 }
 
+typedef struct {
+    char reply[CONN_BUFSIZE + 1U];
+} SMTPRelayTrace;
+
+static int
+CaptureRelayReply(CURL *curl, curl_infotype type, char *data,
+                  size_t size, void *user_data)
+{
+    SMTPRelayTrace *trace = user_data;
+    size_t length;
+
+    (void)curl;
+    if (trace == NULL || type != CURLINFO_HEADER_IN || size < 4U ||
+        !isdigit((unsigned char)data[0]) ||
+        !isdigit((unsigned char)data[1]) ||
+        !isdigit((unsigned char)data[2]) ||
+        (data[3] != ' ' && data[3] != '-'))
+        return 0;
+    length = size < sizeof(trace->reply) - 1U
+        ? size : sizeof(trace->reply) - 1U;
+    while (length > 0U &&
+           (data[length - 1U] == '\r' || data[length - 1U] == '\n'))
+        length--;
+    memcpy(trace->reply, data, length);
+    trace->reply[length] = '\0';
+    return 0;
+}
+
 static BOOL
 DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
              const SMTPRelayRoute *route)
@@ -932,7 +961,9 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
     long response = 0;
     BOOL success = FALSE;
     BongoMailAuthStatus senderStatus;
+    SMTPRelayTrace relayTrace;
 
+    memset(&relayTrace, 0, sizeof(relayTrace));
     recipient->Result = DELIVER_TRY_LATER;
     if (route == NULL || route->host == NULL || route->host[0] == '\0' ||
         route->port < 1 || route->port > 65535 ||
@@ -1078,13 +1109,17 @@ DeliverRelay(SMTPClient *queue, RecipStruct *recipient,
     curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 30L);
     curl_easy_setopt(curl, CURLOPT_TIMEOUT, 300L);
     curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, curlError);
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+    curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, CaptureRelayReply);
+    curl_easy_setopt(curl, CURLOPT_DEBUGDATA, &relayTrace);
     code = curl_easy_perform(curl);
     curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &response);
     if (code == CURLE_OK && response >= 200 && response < 300) {
         recipient->Result = DELIVER_SUCCESS;
         success = TRUE;
     } else if (response >= 500 && code != CURLE_LOGIN_DENIED) {
-        recipient->Result = DELIVER_FAILURE;
+        recipient->Result = SMTPDeliveryResultFromReply(
+            (unsigned int)response, relayTrace.reply);
     }
     Log(success ? LOG_INFO : LOG_WARN,
         "%s %s returned %ld (%s) for message %s to %s",
@@ -1771,8 +1806,8 @@ beginConversation:
 
     if (!ReadRemoteSMTPReply(Remote, &ReplyCode, NULL, NULL) ||
         ReplyCode != 250U) {
-        Recip->Result = ReplyCode / 100U == 5U
-            ? DELIVER_FAILURE : DELIVER_TRY_LATER;
+        Recip->Result = SMTPDeliveryResultFromReply(
+            ReplyCode, Remote->line);
         goto finalization;
     }
 
@@ -1798,9 +1833,8 @@ beginConversation:
      *      4xx are temporary failures and should be re-attempted
      *      5xx are fatal errors */
     if (ReplyCode / 100U == 5U) {
-        Recip->Result = DELIVER_FAILURE;
-
-        /* TODO: am i supposed to bounce the mail here? */
+        Recip->Result = SMTPDeliveryResultFromReply(
+            ReplyCode, Remote->line);
         goto finalization;
     } else if (ReplyCode / 100U != 2U) {
         /* all other errors will be re-tried later */
@@ -1815,8 +1849,8 @@ beginConversation:
 
     if (!ReadRemoteSMTPReply(Remote, &ReplyCode, NULL, NULL) ||
         ReplyCode != 354U) {
-        Recip->Result = ReplyCode / 100U == 5U
-            ? DELIVER_FAILURE : DELIVER_TRY_LATER;
+        Recip->Result = SMTPDeliveryResultFromReply(
+            ReplyCode, Remote->line);
         goto finalization;
     }
 

src/agents/smtp/tests/protocol-test.c

@@ -24,6 +24,8 @@
 #include <assert.h>
 #include <string.h>
 
+#include <nmap.h>
+
 static void
 TestCommands(void)
 {
@@ -399,6 +401,19 @@ TestDsnOptions(void)
     assert(!strcmp(options, ""));
     assert(!SMTPFormatDsnRcptOptions(
         1, SMTP_NOTIFY_NEVER, NULL, 0, options, sizeof(options)));
+
+    assert(SMTPDeliveryResultFromReply(
+               250U, "250 2.1.5 Recipient accepted") == DELIVER_SUCCESS);
+    assert(SMTPDeliveryResultFromReply(
+               451U, "451 4.3.0 Try later") == DELIVER_TRY_LATER);
+    assert(SMTPDeliveryResultFromReply(
+               550U, "550 5.1.1 No such user") == DELIVER_USER_UNKNOWN);
+    assert(SMTPDeliveryResultFromReply(
+               552U, "5.2.2 Mailbox full") == DELIVER_QUOTA_EXCEEDED);
+    assert(SMTPDeliveryResultFromReply(
+               550U, "550 5.7.1 Policy rejection") == DELIVER_BLOCKED);
+    assert(SMTPDeliveryResultFromReply(
+               550U, "550 Rejected") == DELIVER_FAILURE);
 }
 
 int