Changeset 1491 for trunk/lib/protocols_transport.c

Timestamp:

01/21/10 10:10:46 (3 years ago)

Author:

salcock

Message:

• Adjusted the "shortcut" protocol access functions to return NULL if a full header (minus options) is not present.

File:

• trunk/lib/protocols_transport.c (modified) (3 diffs)

trunk/lib/protocols_transport.c

@@ -46 +46 @@
 DLLEXPORT libtrace_tcp_t *trace_get_tcp(libtrace_packet_t *packet) {
         uint8_t proto;
+        uint32_t rem = 0;
         libtrace_tcp_t *tcp;
 
-        tcp=(libtrace_tcp_t*)trace_get_transport(packet,&proto,NULL);
+        tcp=(libtrace_tcp_t*)trace_get_transport(packet,&proto,&rem);
 
         if (!tcp || proto != TRACE_IPPROTO_TCP)
+                return NULL;
+
+        /* We should return NULL if there isn't a full TCP header, because the
+         * caller has no way of telling how much of a TCP header we have
+         * returned - use trace_get_transport() if you want to deal with
+         * partial headers 
+         *
+         * NOTE: We're not going to insist that all the TCP options are present
+         * as well, because lots of traces are snapped after 20 bytes of TCP
+         * header and I don't really want to break libtrace programs that
+         * use this function to process those traces */
+
+        if (rem < sizeof(libtrace_tcp_t))
                 return NULL;
 
@@ -70 +84 @@
 DLLEXPORT libtrace_udp_t *trace_get_udp(libtrace_packet_t *packet) {
         uint8_t proto;
+        uint32_t rem = 0;
         libtrace_udp_t *udp;
 
-        udp=(libtrace_udp_t*)trace_get_transport(packet,&proto,NULL);
+        udp=(libtrace_udp_t*)trace_get_transport(packet,&proto,&rem);
 
         if (!udp || proto != TRACE_IPPROTO_UDP)
+                return NULL;
+
+        /* Make sure we return a full UDP header as the caller has no way of
+         * telling how much of the packet is remaining */
+        if (rem < sizeof(libtrace_udp_t))
                 return NULL;
 
@@ -94 +114 @@
 DLLEXPORT libtrace_icmp_t *trace_get_icmp(libtrace_packet_t *packet) {
         uint8_t proto;
+        uint32_t rem = 0;
         libtrace_icmp_t *icmp;
 
-        icmp=(libtrace_icmp_t*)trace_get_transport(packet,&proto,NULL);
+        icmp=(libtrace_icmp_t*)trace_get_transport(packet,&proto,&rem);
 
         if (!icmp || proto != TRACE_IPPROTO_ICMP)
+                return NULL;
+
+        /* Make sure we return a full ICMP header as the caller has no way of
+         * telling how much of the packet is remaining */
+        if (rem < sizeof(libtrace_icmp_t))
                 return NULL;