[fetchmail-devel] RFC PATCH: Allow envelope to use regular expression to identify recipient

[Earl C. <ear...@ya...>]

Per my post in fetchmail-users (https://lists.berlios.de/pipermail/fetchmail-users/2012-September/003231.html)
here is a candidate patch to enable additional envelope functionality to better identify the intended
recipient in multidrop scenarios.


This patch approaches the enhancement in a straightforward way and is relatively unintrusive.


Apologies for the tab mangling in this RFC.  I can offer up a unmangled version if required to
commit the patch.

Earl



--- fetchmail.h.orig    2012-08-13 13:02:41.000000000 -0700
+++ fetchmail.h    2012-09-03 09:17:37.000000000 -0700
@@ -33,6 +33,7 @@
 #endif
 #include <netdb.h>
 #include <stdio.h>
+#include <regex.h>
 
 /* Import Trio if needed */
 #if !defined(HAVE_SNPRINTF) || !defined(HAVE_VSNPRINTF)
@@ -270,6 +271,7 @@
     int interval;            /* # cycles to skip between polls */
     int authenticate;            /* authentication mode to try */
     int timeout;            /* inactivity timout in seconds */
+    regex_t *envre;            /* envelope address list header regex */
     char *envelope;            /* envelope address list header */
     int envskip;            /* skip to numbered envelope header */
     char *qvirtual;            /* prefix removed from local user id */
--- transact.c.orig    2012-09-03 11:40:42.000000000 -0700
+++ transact.c    2012-09-03 13:04:12.000000000 -0700
@@ -104,6 +104,88 @@
     }
 }
 
+static int match_envelope(char *hdr,
+              struct query *ctl)
+/** compare the envelope with the RFC822 header and potentially rewrite */
+/** \param hdr         RFC822 header in question */
+/** \param ctl         envelope */
+{
+    static regex_t regex_disabled;
+
+    if (hdr == (char *)NULL ||
+    !ctl->server.envelope ||
+    ctl->server.envelope == STRING_DISABLED)
+    {
+       return 0;
+    }
+
+    if (ctl->server.envelope[0] != '^')
+    return strncasecmp(ctl->server.envelope,
+               hdr, strlen(ctl->server.envelope));
+
+    if (ctl->server.envre == (regex_t*)NULL)
+    {
+    int regerr;
+
+    if (outlevel >= O_DEBUG)
+        report(stdout,
+        GT_("compiling envelope regexp %s\n"), ctl->server.envelope);
+
+    ctl->server.envre = (regex_t *)xmalloc(sizeof(*ctl->server.envre));
+    regerr = regcomp(ctl->server.envre, ctl->server.envelope, REG_EXTENDED);
+
+    if (regerr)
+    {
+        report(stderr,
+        GT_("Error %d compling regex: %s\n"),
+        regerr, ctl->server.envelope);
+
+        xfree(ctl->server.envre);
+        ctl->server.envre = &regex_disabled;
+    }
+    }
+
+    if (ctl->server.envre != &regex_disabled)
+    {
+    regmatch_t regmatch[2];
+
+    int matcherr = regexec(ctl->server.envre, hdr, 2, regmatch, 0);
+
+    if (matcherr == 0)
+    {
+        if (regmatch[1].rm_so != -1)
+        {
+        int matchlen = regmatch[1].rm_eo - regmatch[1].rm_so;
+        char *hp = hdr + matchlen + 1;
+
+        memmove(hdr+1, hdr + regmatch[1].rm_so, matchlen);
+        hdr[0] = ':';
+
+        while (*hp != '\0' && *hp != '\r' && *hp != '\n')
+            *hp++ = ' ';
+
+        if (outlevel >= O_DEBUG)
+            report(stdout,
+            GT_("extracted envelope address %s\n"), hdr+1);
+        }
+
+        return 1;
+    }
+
+    if (matcherr != REG_NOMATCH)
+    {
+        char msgbuf[256];
+
+        regerror(matcherr, ctl->server.envre, msgbuf, sizeof(msgbuf));
+
+        report(stderr,
+        GT_("Error matching %s: %s\n"), ctl->server.envelope, msgbuf);
+    }
+    }
+
+    return 0;
+}
+
 static void find_server_names(const char *hdr,
                   struct query *ctl,
                   struct idlist **xmit_names)
@@ -936,9 +1018,7 @@
         if (ctl->server.envelope 
             && strcasecmp(ctl->server.envelope, "Received"))
         {
-            if (env_offs == -1 && !strncasecmp(ctl->server.envelope,
-                               line,
-                               strlen(ctl->server.envelope)))
+            if (env_offs == -1 && match_envelope(line, ctl))
             {                
             if (skipcount++ < ctl->server.envskip)
                 continue;