Patch to add Amateur Radio protocol AX.25 to libpcap

[Richard Stearn <richard () rns-stearn demon co uk>]

Greetings

The attached patch adds recognition for the Amateur Radio AX.25 protocol
to libpcap.  The definition of DLT_AX25 already exists (protocol 3).

I would appreciate the inclusion of this patch into libpcap as I am
attempting to add the Amateur Radio protocols to tcpdump and wireshark.

Longer term I would hope to add address matching but this may be
non-trivial so I would like to get basic capture in place.


--
Regards
        Richard

*** reference/libpcap-0.9.5/gencode.c   2006-09-13 08:36:19.000000000 +0100
--- modified/libpcap-0.9.5/gencode.c    2006-12-05 23:35:00.000000000 +0000
***************
*** 1236,1241 ****
--- 1236,1251 ----
                off_nl = -1;
                off_nl_nosnap = -1;
                return;
+ 
+       case DLT_AX25:
+               /*
+                * Currently, only raw "link[N:M]" filtering is supported.
+                */
+               off_linktype = -1;      /* variable, min 15, max 71 steps of 7 */
+               off_nl = -1;            /* variable, min 16, max 71 steps of 7 */
+               off_nl_nosnap = -1;     /* no 802.2 LLC */
+               off_mac = 1;            /* step over the kiss length byte */
+               return;
        }
        bpf_error("unknown data link type %d", linktype);
        /* NOTREACHED */
*** reference/libpcap-0.9.5/pcap.c      2006-07-27 22:06:17.000000000 +0100
--- modified/libpcap-0.9.5/pcap.c       2006-12-05 23:36:05.000000000 +0000
***************
*** 384,389 ****
--- 384,390 ----
        DLT_CHOICE(DLT_A429, "Arinc 429"),
        DLT_CHOICE(DLT_CAN20B, "Controller Area Network (CAN) v. 2.0B"),
      DLT_CHOICE(DLT_A653_ICM, "Arinc 653 Interpartition Communication"),
+       DLT_CHOICE(DLT_AX25, "AX.25"),
        DLT_CHOICE_SENTINEL
  };
  

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