[Listener] Fix the "don't want to quit" bug

In capture(), the pcap_loop() call was blocking, so the program did not
quit if no packet came on rtap_iface. This is now fixed by a call to
pcap_breakloop() in the signal handlers.

TODO

@@ -35,11 +35,6 @@
 
 - read_packet(): use ieee80211_header_size for all implicit packets
    Currently the size is corrected only for data packets.
-- Fix the "don't want to quit" bug
-   Sometimes owlps-listener refuses to quit on SIGTERM. This is
-   because of the blocking call of pcap_loop() in capture(): something
-   has to be read on rtap_iface before to quit. Maybe we should thread
-   capture(), to be able to pthread_cancel() it.
 - Fix segfault when rtap_iface is not in monitor mode (?) on Foneras.
 - Merge Makefile and Makefile_atheros?
    Use autohell?

owlps-listener/owlps-listener.h

@@ -97,6 +97,9 @@ void send_autocalibration_request(void) ;
 uint_fast16_t make_packet(uint8_t **packet) ;
 #endif // USE_PTHREAD
 
+void sigint_handler(int num) ;
+void sigterm_handler(int num) ;
+
 void print_usage(void) ;
 void print_version(void) ;
 

owlps-listener/owlps-listenerd.c

@@ -11,6 +11,7 @@ char *program_name = NULL ;
 uint8_t my_mac_bytes[6] ; // AP MAC address
 char my_ip[INET_ADDRSTRLEN] ; // AP IP address
 
+pcap_t *capture_handler = NULL ; // Packet capture descriptor
 int aggregation_sockfd ;
 struct sockaddr_in aggregation_server ;
 int autocalibration_send_sockfd ;
@@ -89,9 +90,9 @@ int main(int argc, char *argv[])
 
   /* Set up signal handlers */
   sigemptyset(&action.sa_mask) ;
-  action.sa_handler = owl_sigint_handler ;
+  action.sa_handler = sigint_handler ;
   sigaction(SIGINT, &action, NULL) ;
-  action.sa_handler = owl_sigterm_handler ;
+  action.sa_handler = sigterm_handler ;
   sigaction(SIGTERM, &action, NULL) ;
 
   get_mac_addr(GET_WIFI_IFACE(), my_mac_bytes) ;
@@ -585,12 +586,12 @@ void* keep_mode_monitor(void *iface)
  */
 int capture()
 {
-  pcap_t *handle ; // Packet capture descriptor
   char errbuf[PCAP_ERRBUF_SIZE] ; // Error message
 
   // Start capture:
-  handle = pcap_open_live(GET_RTAP_IFACE(), BUFSIZ, 1, 1000, errbuf) ;
-  if (handle == NULL) // Capture starting failed
+  capture_handler =
+    pcap_open_live(GET_RTAP_IFACE(), BUFSIZ, 1, 1000, errbuf) ;
+  if (capture_handler == NULL) // Capture starting failed
     {
       fprintf(stderr, "Cannot open capture interface %s\n", errbuf) ;
       return ERR_OPENING_IFACE ;
@@ -602,11 +603,11 @@ int capture()
                                 GET_AGGREGATION_PORT(),
                                 &aggregation_server, NULL) ;
 
-  while(run)
+  while (run)
     // Capture one packet at time, and call read_packet() on it:
-    pcap_loop(handle, 1, read_packet, NULL) ;
+    pcap_loop(capture_handler, 1, read_packet, NULL) ;
 
-  pcap_close(handle) ; // Stop capture
+  pcap_close(capture_handler) ; // Stop capture
   close(aggregation_sockfd) ; // Close socket
 
   return 0 ;
@@ -1176,6 +1177,22 @@ uint_fast16_t make_packet(uint8_t **packet)
 
 
 
+void sigint_handler(int num)
+{
+  owl_sigint_handler(num) ;
+  pcap_breakloop(capture_handler) ;
+}
+
+
+
+void sigterm_handler(int num)
+{
+  owl_sigterm_handler(num) ;
+  pcap_breakloop(capture_handler) ;
+}
+
+
+
 void print_usage()
 {
   printf("Usage :\n"