Merge pull request #63 from gadall/gedalya-add-length

Make hash length and hash minimum length configurable

README.exim.md

+PostSRSd integration with Exim
+==============================
+
+## SRS Return router
+
+If using a domain solely for SRS return addresses:
+
+    SRS_DOMAIN = srs.your.domain
+    
+    begin routers
+    
+    srs_return:
+      caseful_local_part
+      domains = SRS_DOMAIN
+      driver = redirect
+      allow_fail
+      data = ${if match {$local_part}{\N(?i)^srs[01]=\N} \
+    	{${if match \
+    	  {${readsocket{inet:localhost:10002}{get ${quote_local_part:$local_part_prefix$local_part}@$domain}{3s}}} \
+    	  {\N^200 (.+)\N} \
+    	  {$1} \
+    	  {:fail: Invalid SRS bounce} \
+    	}} \
+    	{:fail: Invalid SRS bounce} \
+      }
+      no_more
+
+If your SRS domain is also used for other addresses:
+
+    SRS_DOMAIN = srs.your.domain
+    
+    begin routers
+    
+    srs_return:
+      caseful_local_part
+      domains = SRS_DOMAIN
+      local_part_prefix = srs0= : srs1=
+      driver = redirect
+      allow_fail
+      data = ${if match \
+        {${readsocket{inet:localhost:10002}{get ${quote_local_part:$local_part_prefix$local_part}@$domain}{3s}}} \
+        {\N^200 (.+)\N} \
+        {$1} \
+        {:fail: Invalid SRS bounce} \
+      }
+
+## Rewriting outgoing mail in the SMTP transport
+
+The following excludes locally submitted mail, or mail submitted by authenticated
+users from SRS rewriting. Of course, if the sender address is already in
+one of our local domains, there is no need to rewrite the address.
+
+    begin transports
+    
+    remote_smtp:
+      debug_print = "T: remote_smtp for $local_part@$domain"
+      driver = smtp
+      return_path = ${if and { \
+    		{!match_ip{$sender_host_address}{:@[]}} \
+    		{!def:authenticated_id} \
+    		{!match_address {$sender_address} { : *@+local_domains : *@+virtual_domains : SRS_DOMAIN}} \
+    	} \
+    	{${if match \
+    	  {${readsocket{inet:localhost:10001}{get $sender_address}{3s}}} \
+    	  {\N^200 (.+)\N} \
+    	  {$1} \
+    	  fail } \
+    	} \
+    	fail }

README.md

 - The Postfix package in CentOS 6 lacks the required support for TCP
   dictionaries. Please upgrade your distribution or build Postfix yourself.
 
+Use with Exim
+-------------
+
+Exim configuration examples can be found in [README.exim.md](README.exim.md)

init/postsrsd.default.in

 #
 SRS_SECRET=@SYSCONF_DIR@/@PROJECT_NAME@.secret
 
+# Length of hash to be used in rewritten addresses
+SRS_HASHLENGTH=4
+
+# Minimum length of hash to accept when validating return addresses.
+# When increasing SRS_HASHLENGTH, set this to its previous value and
+# wait for the duration of SRS return address validity (21 days) before
+# increading this value as well.
+SRS_HASHMIN=4
+
 # Local ports for TCP list.
 # These ports are used to bind the TCP list for postfix. If you change
 # these, you have to modify the postfix settings accordingly. The ports

init/postsrsd.systemd.in

 # Load the real configuration.
 EnvironmentFile=@CONFIG_DIR@/@PROJECT_NAME@
 
-ExecStart=@CMAKE_INSTALL_PREFIX@/sbin/@POSTSRSD@ -f "${SRS_FORWARD_PORT}" -r "${SRS_REVERSE_PORT}" -d "${SRS_DOMAIN}" -s "${SRS_SECRET}" -a "${SRS_SEPARATOR}" -u "${RUN_AS}" -c "${CHROOT}" -X"${SRS_EXCLUDE_DOMAINS}"
+ExecStart=@CMAKE_INSTALL_PREFIX@/sbin/@POSTSRSD@ -f "${SRS_FORWARD_PORT}" -r "${SRS_REVERSE_PORT}" -d "${SRS_DOMAIN}" -s "${SRS_SECRET}" -a "${SRS_SEPARATOR}" -n "${SRS_HASHLENGTH}" -N "${SRS_HASHMIN}" -u "${RUN_AS}" -c "${CHROOT}" -X"${SRS_EXCLUDE_DOMAINS}"
 
 [Install]
 WantedBy=multi-user.target

init/postsrsd.sysv-lsb.in

 		--pidfile $PIDFILE \
 		--name $NAME \
 		--startas $DAEMON \
-		-- -f "$SRS_FORWARD_PORT" -r "$SRS_REVERSE_PORT" -d "$SRS_DOMAIN" -s "$SRS_SECRET" -a "$SRS_SEPARATOR" -u "$RUN_AS" -p "$PIDFILE" -c "$CHROOT" -D -X"$SRS_EXCLUDE_DOMAINS"
+		-- -f "$SRS_FORWARD_PORT" -r "$SRS_REVERSE_PORT" -d "$SRS_DOMAIN" -s "$SRS_SECRET" -a "$SRS_SEPARATOR" -n "$SRS_HASHLENGTH" -N "$SRS_HASHMIN" -u "$RUN_AS" -p "$PIDFILE" -c "$CHROOT" -D -X"$SRS_EXCLUDE_DOMAINS"
 	then
 	    log_end_msg 0
 	else

init/postsrsd.sysv-redhat.in

 do_start()
 {
 	echo -n "Starting $DESC: "
-	daemon $DAEMON -f "$SRS_FORWARD_PORT" -r "$SRS_REVERSE_PORT" -d "$SRS_DOMAIN" -s "$SRS_SECRET" \
+	daemon $DAEMON -f "$SRS_FORWARD_PORT" -r "$SRS_REVERSE_PORT" -d "$SRS_DOMAIN" \
+	               -s "$SRS_SECRET" -n "$SRS_HASHLENGTH" -N "$SRS_HASHMIN" \
 	               -u "$RUN_AS" -p "$PIDFILE" -a "$SRS_SEPARATOR" -c "$CHROOT" -D -X"$SRS_EXCLUDE_DOMAINS"
 	RETVAL=$?
 	echo

init/postsrsd.upstart.in

 	SRS_DOMAIN=`postconf -h mydomain || true`
 	SRS_EXCLUDE_DOMAINS=
 	. "@CONFIG_DIR@/@PROJECT_NAME@"
-	exec @CMAKE_INSTALL_PREFIX@/sbin/@POSTSRSD@ -f "$SRS_FORWARD_PORT" -r "$SRS_REVERSE_PORT" -d "$SRS_DOMAIN" -s "$SRS_SECRET" -a "$SRS_SEPARATOR" -u "$RUN_AS" -c "$CHROOT" -X"$SRS_EXCLUDE_DOMAINS"
+	exec @CMAKE_INSTALL_PREFIX@/sbin/@POSTSRSD@ -f "$SRS_FORWARD_PORT" -r "$SRS_REVERSE_PORT" -d "$SRS_DOMAIN" -s "$SRS_SECRET" -a "$SRS_SEPARATOR" -n "$SRS_HASHLENGTH" -N "$SRS_HASHMIN" -u "$RUN_AS" -c "$CHROOT" -X"$SRS_EXCLUDE_DOMAINS"
 end script
 

postsrsd.c

     "   -s<file>       read secrets from file (required)\n"
     "   -d<domain>     set domain name for rewrite (required)\n"
     "   -a<char>       set first separator character which can be one of: -=+ (default: =)\n"
+    "   -n<num>        length of hash to be used in rewritten addresses (default: 4)\n"
+    "   -N<num>        minimum length of hash to accept for validation (default: 4)\n"
     "   -l<addr>       set socket listen address (default: 127.0.0.1)\n"
     "   -f<port>       set port for the forward SRS lookup (default: 10001)\n"
     "   -r<port>       set port for the reverse SRS lookup (default: 10002)\n"
 
 int main (int argc, char **argv)
 {
-  int opt, timeout = 1800, family = AF_UNSPEC;
+  int opt, timeout = 1800, family = AF_UNSPEC, hashlength = 0, hashmin = 0;
   int daemonize = FALSE;
   char *listen_addr = NULL, *forward_service = NULL, *reverse_service = NULL,
        *user = NULL, *domain = NULL, *chroot_dir = NULL;
   tmp = strrchr(argv[0], '/');
   if (tmp) self = strdup(tmp + 1); else self = strdup(argv[0]);
 
-  while ((opt = getopt(argc, argv, "46d:a:l:f:r:s:u:t:p:c:X::Dhev")) != -1) {
+  while ((opt = getopt(argc, argv, "46d:a:l:f:r:s:n:N:u:t:p:c:X::Dhev")) != -1) {
     switch (opt) {
       case '?':
         return EXIT_FAILURE;
       case 's':
         secret_file = strdup(optarg);
         break;
+      case 'n':
+        hashlength = atoi(optarg);
+        break;
+      case 'N':
+        hashmin = atoi(optarg);
+        break;
       case 'p':
         pid_file = strdup(optarg);
         break;
           domain = strdup(getenv("SRS_DOMAIN"));
         if ( getenv("SRS_SEPARATOR") != NULL )
           separator = *getenv("SRS_SEPARATOR");
+        if ( getenv("SRS_HASHLENGTH") != NULL )
+          hashlength = atoi(getenv("SRS_HASHLENGTH"));
+        if ( getenv("SRS_HASHMIN") != NULL )
+          hashmin = atoi(getenv("SRS_HASHMIN"));
         if ( getenv("SRS_FORWARD_PORT") != NULL )
           forward_service = strdup(getenv("SRS_FORWARD_PORT"));
         if ( getenv("SRS_REVERSE_PORT") != NULL )
   fclose (sf);
 
   srs_set_separator (srs, separator);
+  if (hashlength)
+    srs_set_hashlength (srs, hashlength);
+  if (hashmin)
+    srs_set_hashmin (srs, hashmin);
 
   for (sc = 0; sc < socket_count; ++sc) {
     fds[sc].fd = sockets[sc];

srs2.c

 	len = strlen(hash);
 	if (len < srs->hashmin)
 		return SRS_EHASHTOOSHORT;
-	if (len < srs->hashlength) {
+	if (len > srs->hashlength) {
 		tmp = alloca(srs->hashlength + 1);
 		strncpy(tmp, hash, srs->hashlength);
 		tmp[srs->hashlength] = '\0';