From 8474fef52077a4ae30bbdeac05839ff09c8cb4c9 Mon Sep 17 00:00:00 2001
From: Matteo Cypriani <matteo.cypriani@univ-fcomte.fr>
Date: Tue, 23 Nov 2010 18:29:32 +0100
Subject: [PATCH] [Listener] Reorganise implicit/explicit code

Reorganise read_packet() code for detection of implicit/explicit
requests. Quite buggy, it was.

Word of the day: OMG GOTOZ LOL111
---
 .../owlps-listener/owlps-listenerd.c          | 78 +++++++++----------
 1 file changed, 35 insertions(+), 43 deletions(-)

diff --git a/infrastructure-centred/owlps-listener/owlps-listenerd.c b/infrastructure-centred/owlps-listener/owlps-listenerd.c
index 42c8eb2..0e93896 100644
--- a/infrastructure-centred/owlps-listener/owlps-listenerd.c
+++ b/infrastructure-centred/owlps-listener/owlps-listenerd.c
@@ -492,6 +492,7 @@ void read_packet(u_char *args, const struct pcap_pkthdr *header,
   BOOL is_explicit_packet = TRUE ; // Is the packet an explicit request?
   int i ; // Iterator
 
+  bzero(couple.mobile_ip_addr_bytes, 4) ; // Blank the IP
 
   /* Common treatements */
 
@@ -505,53 +506,44 @@ void read_packet(u_char *args, const struct pcap_pkthdr *header,
   // is the packet type (beacon or not):
   raw_packet_type = data[rtap_bytes] ;
 
-  if (raw_packet_type == RAW_PACKET_TYPE_DATA) // Data packet
+  if (raw_packet_type != RAW_PACKET_TYPE_DATA) // Data packet?
+    goto not_explicit_packet ;
+
+  // Get the packet type (protocol, 2 bytes) from the LLC header:
+  memcpy((unsigned char*) &llc_packet_type,
+         &data[rtap_bytes + IEEE80211_HEADER_SIZE + 6], 2) ;
+  llc_packet_type = ntohs(llc_packet_type) ;
+
+  if (llc_packet_type != ETH_P_IP) // IP packet?
+    goto not_explicit_packet ;
+
+  packet_ip_header = (struct iphdr *)
+    &data[rtap_bytes + IEEE80211_HEADER_SIZE + LLC_HEADER_SIZE] ;
+  // Get the source IP:
+  memcpy(couple.mobile_ip_addr_bytes, &packet_ip_header->saddr, 4) ;
+
+  if (GET_MODE() != MODE_PASSIVE) // If mode is active or mixed
     {
-      // Get the packet type (protocol, 2 bytes) from the LLC header:
-      memcpy((unsigned char*) &llc_packet_type,
-             &data[rtap_bytes + IEEE80211_HEADER_SIZE + 6], 2) ;
-      llc_packet_type = ntohs(llc_packet_type) ;
+      // Protocol for an explicit request is UDP
+      if (packet_ip_header->protocol != IPPROTO_UDP)
+        goto not_explicit_packet ;
 
-      if (llc_packet_type == ETH_P_IP) // IP packet
-        {
-          packet_ip_header = (struct iphdr *)
-            &data[rtap_bytes + IEEE80211_HEADER_SIZE + LLC_HEADER_SIZE] ;
-          // Get the source IP:
-          memcpy(couple.mobile_ip_addr_bytes, &packet_ip_header->saddr, 4) ;
-
-          if (GET_MODE() != MODE_PASSIVE) // If mode is active or mixed
-            {
-              // Protocol for an explicit request is UDP
-              if (packet_ip_header->protocol == IPPROTO_UDP)
-                { // Check destination port:
-                  packet_udp_header = (struct udphdr *)
-                    &data[rtap_bytes + IEEE80211_HEADER_SIZE +
-                          LLC_HEADER_SIZE + sizeof(struct iphdr)] ;
-                  if (ntohs(packet_udp_header->dest) !=
-                      GET_LISTENING_PORT())
-                    {
-                      if (GET_MODE() == MODE_ACTIVE)
-                        return ;
-                      is_explicit_packet = FALSE ;
-                    }
-                }
-            }
-        }
-      else if (GET_MODE() != MODE_ACTIVE) // Passive or mixed mode
-        {
-          is_explicit_packet = FALSE ;
-          bzero(couple.mobile_ip_addr_bytes, 4) ; // Blank the IP
-        }
-      else // Active mode and not an IP packet, so it is not a request
-        return ;
+      // Check destination port:
+      packet_udp_header = (struct udphdr *)
+        &data[rtap_bytes + IEEE80211_HEADER_SIZE +
+              LLC_HEADER_SIZE + sizeof(struct iphdr)] ;
+      if (ntohs(packet_udp_header->dest) != GET_LISTENING_PORT())
+        goto not_explicit_packet ;
     }
 
-  else // Packet is not data, so it is not a localisation request
-    {
-      if (GET_MODE() == MODE_ACTIVE)
-        return ;
-      is_explicit_packet = FALSE ;
-    }
+  goto process_packet ;
+
+ not_explicit_packet :
+  if (GET_MODE() == MODE_ACTIVE)
+    return ;
+  is_explicit_packet = FALSE ;
+
+ process_packet :
 
   // Get 802.11 flags from the 802.11 header:
   raw_packet_flags = data[rtap_bytes+1] ;