Make SRS separator configurable

init/postsrsd.default.in

 #
 #SRS_EXCLUDE_DOMAINS=.example.com,example.org
 
+# First separator character after SRS0 or SRS1.
+# Can be one of: -+=
+#SRS_SEPARATOR==
+
 # Secret key to sign rewritten addresses.
 # When postsrsd is installed for the first time, a random secret is generated
 # and stored in /etc/postsrsd.secret. For most installations, that's just fine.

postsrsd.c

     "Options:\n"
     "   -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"
     "   -f<port>       set port for the forward SRS lookup (default: 10001)\n"
     "   -r<port>       set port for the reverse SRS lookup (default: 10002)\n"
     "   -p<pidfile>    write process ID to pidfile (default: none)\n"
   int daemonize = FALSE;
   char *forward_service = NULL, *reverse_service = NULL,
        *user = NULL, *domain = NULL, *chroot_dir = NULL;
+  char separator = '=';
   int forward_sock, reverse_sock;
   char *secret_file = NULL, *pid_file = NULL;
   FILE *pf = NULL, *sf = NULL;
   tmp = strrchr(argv[0], '/');
   if (tmp) self = strdup(tmp + 1); else self = strdup(argv[0]);
 
-  while ((opt = getopt(argc, argv, "46d:f:r:s:u:t:p:c:X::Dhev")) != -1) {
+  while ((opt = getopt(argc, argv, "46d:a:f:r:s:u:t:p:c:X::Dhev")) != -1) {
     switch (opt) {
       case '?':
         return EXIT_FAILURE;
       case 'd':
         domain = strdup(optarg);
         break;
+      case 'a':
+        separator = *optarg;
+        break;
       case 'f':
         forward_service = strdup(optarg);
         break;
       case 'e':
         if ( getenv("SRS_DOMAIN") != NULL )
           domain = strdup(getenv("SRS_DOMAIN"));
+        if ( getenv("SRS_SEPARATOR") != NULL )
+          separator = *getenv("SRS_SEPARATOR");
         if ( getenv("SRS_FORWARD_PORT") != NULL )
           forward_service = strdup(getenv("SRS_FORWARD_PORT"));
         if ( getenv("SRS_REVERSE_PORT") != NULL )
     return EXIT_FAILURE;
   }
 
+  if (separator != '=' && separator != '+' && separator != '-') {
+    fprintf (stderr, "%s: SRS separator character must be one of '=+-'\n", self);
+    return EXIT_FAILURE;
+  }
+
   /* The stuff we do first may not be possible from within chroot or without privileges */
 
   /* Open pid file for writing (the actual process ID is filled in later) */
       srs_add_secret (srs, secret);
   }
   fclose (sf);
-  srs_set_separator (srs, '+');
+
+  srs_set_separator (srs, separator);
 
   fds[0].fd = forward_sock;
   fds[0].events = POLLIN;