Added --packet-limit to fwknopd so that the number of incoming candidate

SPA packets can be limited from the command line.  When this limit is
reached (any packet that contains application layer data and passes the
pcap filter is included in the count) then fwknopd exits.



git-svn-id: file:///home/mbr/svn/fwknop/trunk@179 510a4753-2344-4c79-9c09-4d669213fbeb

ChangeLog

@@ -1,3 +1,9 @@
+2010-01-02  Michael Rash  <mbr@cipherdyne.org>
+	* Added --packet-limit to fwknopd so that the number of incoming candidate
+	  SPA packets can be limited from the command line.  When this limit is
+	  reached (any packet that contains application layer data and passes the
+	  pcap filter is included in the count) then fwknopd exits.
+
 2009-11-01  Michael Rash  <mbr@cipherdyne.org>
 	* (Legacy code) Applied patch from Jonthan Bennett to support the usage of
 	  the http_proxy environmental variable for sending SPA packets through an

server/config_init.c

@@ -316,7 +316,7 @@ config_init(fko_srv_options_t *opts, int argc, char **argv)
      * file.
     */
     set_config_entry(opts, CONF_HOSTNAME, opts->hostname);
-    
+
     /* In case this is a re-config.
     */
     optind = 0;
@@ -421,6 +421,9 @@ config_init(fko_srv_options_t *opts, int argc, char **argv)
             case 'c':
                 /* This was handled earlier */
                 break;
+            case 'C':
+                opts->packet_ctr_limit = atoi(optarg);
+                break;
             case 'D':
                 opts->dump_config = 1;
                 break;
@@ -511,6 +514,8 @@ usage(void)
       "Usage: fwknopd [options]\n\n"
       " -h, --help              - Print this usage message and exit.\n"
       " -c, --config-file       - Specify an alternate configuration file.\n"
+      " -C, --packet-limit      - Limit the number of candidate SPA packets to\n"
+      "                           process and exit when this limit is reached.\n"
       " -D, --dump-config       - Dump the current fwknop configuration values.\n"
       " -f, --foreground        - Run fwknopd in the foreground so that it never\n"
       "                           forks off into the background.\n"

server/config_init.h

@@ -63,13 +63,14 @@ enum {
 
 /* Our getopt_long options string.
 */
-#define GETOPTS_OPTION_STRING "c:Dfhi:KO:RSvV"
+#define GETOPTS_OPTION_STRING "c:C:Dfhi:KO:RSvV"
 
 /* Our program command-line options...
 */
 static struct option cmd_opts[] =
 {
     {"config-file",         1, NULL, 'c'},
+    {"packet-limit",        1, NULL, 'C'},
     {"dump-config",         0, NULL, 'D'},
     {"foreground",          0, NULL, 'f'},
     {"fw-list",             0, NULL, FIREWALL_LIST },

server/fwknopd.c

@@ -259,6 +259,13 @@ main(int argc, char **argv)
                 break;
             }
         }
+        else if (opts.packet_ctr >= opts.packet_ctr_limit)
+        {
+            log_msg(LOG_INFO|LOG_STDERR,
+                "Packet count limit (%d) reached.  Exiting...",
+                opts.packet_ctr_limit);
+            break;
+        }
         else    /* got_signal was not set (should be if we are here) */
         {
             log_msg(LOG_WARNING|LOG_STDERR,

server/fwknopd_common.h

@@ -287,6 +287,12 @@ typedef struct fko_srv_options
 
     spa_pkt_info_t  spa_pkt;            /* The current SPA packet */
 
+    /* Counter set from the command line to exit after the specified
+     * number of SPA packets are processed.
+    */
+    unsigned int    packet_ctr_limit;
+    unsigned int    packet_ctr;  /* counts packets with >0 payload bytes */
+
     /* This array holds all of the config file entry values as strings
      * indexed by their tag name.
     */

server/pcap_capture.c

@@ -154,6 +154,17 @@ pcap_capture(fko_srv_options_t *opts)
         {
             incoming_spa(opts);
 
+            /* Count this packet since it has at least one byte of payload
+             * data - we use this as a comparison for --packet-limit regardless
+             * of SPA packet validity at this point.
+            */
+            opts->packet_ctr++;
+            if (opts->packet_ctr >= opts->packet_ctr_limit)
+            {
+                pcap_breakloop(pcap);
+                pending_break = 1;
+            }
+
             pcap_errcnt = 0;
             continue;
         }