mailto: Wait for server opening message

A subset of all mailserver configurations reject SMTP sessions where the
client sends anything before the server sent its opening message. This
is the case with Exim on Ubuntu Artful, for example:

  SMTP protocol synchronization error (input sent without waiting for
  greeting)

Not waiting for the opening message is a violation of the session
initiation described in RFC5321 (section 3.1). Update the mailto
notifier to wait for a non-error status code from the server before
proceeding to start the mail transaction.

diff --git a/notifier/mailto.c b/notifier/mailto.c
index a05addf6279dfe4f656f05b064b5cdd67fe0a983..9b3aeccaba1bec14f908d60a0f7dab90b2cae2f7 100644 (file)
--- a/notifier/mailto.c
+++ b/notifier/mailto.c
@@ -248,6 +248,10 @@ email_message(const char *to,              /* I - Recipient of message */
 
     fprintf(stderr, "DEBUG: Connected to \"%s\"...\n", mailtoSMTPServer);
 
+    if (!cupsFileGets(fp, response, sizeof(response)) || atoi(response) >= 500)
+      goto smtp_error;
+    fprintf(stderr, "DEBUG: <<< %s\n", response);
+
     cupsFilePrintf(fp, "HELO %s\r\n",
                    httpGetHostname(NULL, hostbuf, sizeof(hostbuf)));
     fprintf(stderr, "DEBUG: >>> HELO %s\n", hostbuf);