Based on work from Florent Drouin, split the 32-bit link-layer type

[libpcap] / pcap-dag.c

diff --git a/pcap-dag.c b/pcap-dag.c
index 477c632aa608766cbd1156be00286ea7d2ec1f67..86df4f68aaa698cce65530bd021fbe91a4eb4aa6 100644 (file)
--- a/pcap-dag.c
+++ b/pcap-dag.c
@@ -17,7 +17,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-       "@(#) $Header: /tcpdump/master/libpcap/pcap-dag.c,v 1.29 2007-06-22 06:32:06 guy Exp $ (LBL)";
+       "@(#) $Header: /tcpdump/master/libpcap/pcap-dag.c,v 1.30 2007-09-29 19:33:29 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -644,24 +644,45 @@ dag_open_live(const char *device, int snaplen, int promisc, int to_ms, char *ebu
         */
        handle->md.dag_mem_bottom = 0;
        handle->md.dag_mem_top = 0;
-       handle->md.dag_fcs_bits = 32;
 
-       /* Query the card first for special cases. */
+       /*
+        * Find out how many FCS bits we should strip.
+        * First, query the card to see if it strips the FCS.
+        */
        daginf = dag_info(handle->fd);
-       if ((0x4200 == daginf->device_code) || (0x4230 == daginf->device_code))
-       {
+       if ((0x4200 == daginf->device_code) || (0x4230 == daginf->device_code)) {
                /* DAG 4.2S and 4.23S already strip the FCS.  Stripping the final word again truncates the packet. */
                handle->md.dag_fcs_bits = 0;
-       }
 
-       /* Then allow an environment variable to override. */
-       if ((s = getenv("ERF_FCS_BITS")) != NULL) {
-               if ((n = atoi(s)) == 0 || n == 16|| n == 32) {
-                       handle->md.dag_fcs_bits = n;
-               } else {
-                       snprintf(ebuf, PCAP_ERRBUF_SIZE,
-                               "pcap_open_live %s: bad ERF_FCS_BITS value (%d) in environment\n", device, n);
-                       goto failstop;
+               /* Note that no FCS will be supplied. */
+               handle->linktype_ext = LT_FCS_DATALINK_EXT(0);
+       } else {
+               /*
+                * Start out assuming it's 32 bits.
+                */
+               handle->md.dag_fcs_bits = 32;
+
+               /* Allow an environment variable to override. */
+               if ((s = getenv("ERF_FCS_BITS")) != NULL) {
+                       if ((n = atoi(s)) == 0 || n == 16 || n == 32) {
+                               handle->md.dag_fcs_bits = n;
+                       } else {
+                               snprintf(ebuf, PCAP_ERRBUF_SIZE,
+                                       "pcap_open_live %s: bad ERF_FCS_BITS value (%d) in environment\n", device, n);
+                               goto failstop;
+                       }
+               }
+
+               /*
+                * Did the user request that they not be stripped?
+                */
+               if ((s = getenv("ERF_DONT_STRIP_FCS")) != NULL) {
+                       /* Yes.  Note the number of bytes that will be
+                          supplied. */
+                       handle->linktype_ext = LT_FCS_DATALINK_EXT(handle->md.dag_fcs_bits/16);
+
+                       /* And don't strip them. */
+                       handle->md.dag_fcs_bits = 0;
                }
        }