Changeset 1803a27 for lib/protocols.c

Timestamp:

05/15/07 14:52:53 (15 years ago)

Author:

Scott Raynel <smr26@…>

Branches:

4.0.1-hotfixes, cachetimestamps, develop, dpdk-ndag, etsilive, getfragoff, help, libtrace4, master, ndag_format, pfring, rc-4.0.1, rc-4.0.2, rc-4.0.3, rc-4.0.4, ringdecrementfix, ringperformance, ringtimestampfixes

Children:

f898a97

Parents:

89bfc98

Message:

Fixes in get_payload_from_80211():

• Detect the presence of 802.2 LLC/SNAP in 802.11 and skip accordingly
• Detect whether an 802.11 MAC frame has 3 or 4 MAC addresses and skip accordingly

File:

• lib/protocols.c (modified) (3 diffs)

lib/protocols.c

@@ -114 +114 @@
 static void *trace_get_payload_from_80211(void *link, uint16_t *type, uint32_t *remaining)
 {
-        /* TODO: Decode type != DATA
-         * TODO: We're assuming four address frame here... probably not good
-         */
-        
         libtrace_80211_t *wifi;
         libtrace_802_11_payload_t *eth;
-        uint8_t extra = 0; /* how many QoS bytes to skip */
+        int8_t extra = 0; /* how many QoS bytes to skip */
         
         if (remaining && *remaining < sizeof(libtrace_80211_t))
@@ -132 +128 @@
         }
 
+        /* If FromDS and ToDS are both set then we have a four-address
+         * frame. Otherwise we have a three-address frame */
+        if (!(wifi->to_ds && wifi->from_ds)) 
+                extra -= 6; 
+        
         /* Indicates QoS field present, see IEEE802.11e-2005 pg 21 */
         if (wifi->subtype & 0x8) 
@@ -140 +141 @@
 
         eth=(libtrace_802_11_payload_t *)((char*)wifi+sizeof(*wifi)+extra);
-
+        
+        if (eth->type == 0xaaaa)
+                /* Payload contains an 802.2 LLC/SNAP frame */
+                return trace_get_payload_from_llcsnap((void *)eth, type, remaining);
+                        
+        /* Otherwise we assume an Ethernet II frame */
         if (type) *type=ntohs(eth->type);
         if (remaining) *remaining = *remaining - sizeof(libtrace_80211_t) - extra - sizeof(*eth);
-        
         
         return (void*)((char*)eth+sizeof(*eth));