From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Tue, 12 May 2020 23:58:32 +0000 (+0100)
Subject: Fix over-long line in DSN
X-Git-Url: https://git.exim.org/users/jgh/exim.git/commitdiff_plain/a050bbe0d120464d80dab3eb8af420c4ec686ca8?hp=599fc3c68f5e942c1d662012053ecfc6ea26bd49

Fix over-long line in DSN
---

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 3cd92b816..1682a78b7 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -199,6 +199,10 @@ JH/42 Internationalisation: change the default for downconversion in the smtp
       transport.  The change does mean that addresses needing conversion will
       be converted when previously a delivery failure would occur.
 
+JH/43 Fix possible long line in DSN.  Previously when a very long SMTP error
+      response was received it would be used unchecked in a fail-DSN, violating
+      standards on line-length limits.  Truncate if needed.
+
 
 Exim version 4.93
 -----------------
diff --git a/src/src/deliver.c b/src/src/deliver.c
index 85b061b30..40db50084 100644
--- a/src/src/deliver.c
+++ b/src/src/deliver.c
@@ -5380,7 +5380,8 @@ Returns:       nothing
 static void
 print_dsn_diagnostic_code(const address_item *addr, FILE *f)
 {
-uschar *s = testflag(addr, af_pass_message) ? addr->message : NULL;
+uschar * s = testflag(addr, af_pass_message) ? addr->message : NULL;
+unsigned cnt;
 
 /* af_pass_message and addr->message set ? print remote host answer */
 if (s)
@@ -5392,19 +5393,32 @@ if (s)
   if (!(s = Ustrstr(addr->message, ": ")))
     return;				/* not found, bail out */
   s += 2;  /* skip ": " */
-  fprintf(f, "Diagnostic-Code: smtp; ");
+  cnt = fprintf(f, "Diagnostic-Code: smtp; ");
   }
 /* no message available. do nothing */
 else return;
 
 while (*s)
+  {
+  if (cnt > 950)	/* RFC line length limit: 998 */
+    {
+    DEBUG(D_deliver) debug_printf("print_dsn_diagnostic_code() truncated line\n");
+    fputs("[truncated]", f);
+    break;
+    }
+
   if (*s == '\\' && s[1] == 'n')
     {
     fputs("\n ", f);    /* as defined in RFC 3461 */
     s += 2;
+    cnt += 2;
     }
   else
+    {
     fputc(*s++, f);
+    cnt++;
+    }
+  }
 
 fputc('\n', f);
 }
@@ -7831,11 +7845,11 @@ wording. */
 	    fprintf(fp, "Remote-MTA: X-ip; [%s]%s\n", hu->address, p);
 	    }
 	  if ((s = addr->smtp_greeting) && *s)
-	    fprintf(fp, "X-Remote-MTA-smtp-greeting: X-str; %s\n", s);
+	    fprintf(fp, "X-Remote-MTA-smtp-greeting: X-str; %.900s\n", s);
 	  if ((s = addr->helo_response) && *s)
-	    fprintf(fp, "X-Remote-MTA-helo-response: X-str; %s\n", s);
+	    fprintf(fp, "X-Remote-MTA-helo-response: X-str; %.900s\n", s);
 	  if ((s = addr->message) && *s)
-	    fprintf(fp, "X-Exim-Diagnostic: X-str; %s\n", s);
+	    fprintf(fp, "X-Exim-Diagnostic: X-str; %.900s\n", s);
 	  }
 #endif
 	  print_dsn_diagnostic_code(addr, fp);