Re: Linux Frame-Relay and misc

[Krzysztof Halasa <khc () pm waw pl>]

Hi,

I have prepared a patch (attached below) for tcpdump/print-fr.c. It isn't
a small change, so I understand it may be unacceptable in current form.
Comments will be appreciated.

I've also attached test dumps from CCITT and ANSI LMI packet exchange
and a test ping (IP on FR) dump. Tested with Linux.

Changes:
1. Unused things (mbuf, rtentry, #include "addrtoname.h") have been removed.

2. I've dropped FR_CR_BIT etc. definitions as they have only meaning in
   specific location in Q.922 address. FR_EA_BIT is still there as it's
   used by all Q.922 bytes.

3. a new parse_q922_addr() parses the whole Q.922 address structure
   and produces DLCI, Q.922 byte count and flags in ASCII. While I can't
   test 3- and 4-byte Q.922 addresses (using only default 2-byte ones),
   they are supported.

4. I've trimmed comments regarding HDLC flags and CRC/FCS bytes in FR
   packet. They are wire-only things and as such are never seen by
   libpcap/tcpdump.

5. Changed NLPID_LMI into NLPID_CISCO_LMI and NLPID_Q933 into NLPID_LMI
   (the latter is used by both ANSI (T1.617 annex D) and CCITT (Q.933
   annex A) LMI).

6. fr_hdrlen() now correctly returns FR header length (4 - 6 bytes,
   7 bytes with 4-byte Q.922 and incorrectly used pad byte).

7. I've changed output text formatting: "xxx-value-yyy-value" into
   "xxx value, yyy value", to be consistent with Ethernet.
   Not sure if it's correct.

8. added IPv6 support

9. q933_print() now reads lmi_print()

10. CCITT (Q.933 annex A) LMI is now supported, and both CCITT and ANSI
    fields are now correctly displayed

10. lmi_print() no longer prints constant fields (such as always zeroed
    Q.922 C/R bit or LMI Call Reference byte) unless they are set
    incorrectly.

11. I've added ANSI_ and CCITT_ prefixes to appropriate #defines.

12. a new parse_dlci_el() should handle all (10, 16 and 23-bit)
    DLCIs correctly (corresponding to 2, 3 and 4-byte Q.922 addresses,
    respectively).


With CCITT LMI tcpdump now produces something like:
00:31:01.165621 DLCI 0, LMI, length 9: CCITT STATUS ENQUIRY
                IE: 51 Len: 1, LINK VERIFY
                IE: 53 Len: 2, TX Seq:   9, RX Seq:   8

00:31:01.166077 DLCI 0, LMI, length 24: CCITT STATUS REPLY
                IE: 51 Len: 1, FULL STATUS
                IE: 53 Len: 2, TX Seq:   9, RX Seq:   9
                IE: 57 Len: 3, DLCI 101: status Active
                IE: 57 Len: 3, DLCI 102: status Inactive
                IE: 57 Len: 3, DLCI 110: status Active

00:31:11.164085 DLCI 0, LMI, length 9: CCITT STATUS ENQUIRY
                IE: 51 Len: 1, LINK VERIFY
                IE: 53 Len: 2, TX Seq:  10, RX Seq:   9

00:31:11.164474 DLCI 0, LMI, length 9: CCITT STATUS REPLY
                IE: 51 Len: 1, LINK VERIFY
                IE: 53 Len: 2, TX Seq:  10, RX Seq:  10

With ANSI:
00:26:44.535636 DLCI 0, LMI, length 10: ANSI STATUS ENQUIRY
                IE: 01 Len: 1, FULL STATUS
                IE: 03 Len: 2, TX Seq:  83, RX Seq:  81

00:26:44.536103 DLCI 0, LMI, length 25: ANSI STATUS REPLY
                IE: 01 Len: 1, FULL STATUS
                IE: 03 Len: 2, TX Seq:  82, RX Seq:  83
                IE: 07 Len: 3, DLCI 101: status Active
                IE: 07 Len: 3, DLCI 102: status Inactive
                IE: 07 Len: 3, DLCI 110: status Active

00:26:54.534114 DLCI 0, LMI, length 10: ANSI STATUS ENQUIRY
                IE: 01 Len: 1, LINK VERIFY
                IE: 03 Len: 2, TX Seq:  84, RX Seq:  82

00:26:54.534521 DLCI 0, LMI, length 10: ANSI STATUS REPLY
                IE: 01 Len: 1, LINK VERIFY
                IE: 03 Len: 2, TX Seq:  83, RX Seq:  84


ping shows:
19:24:53.652794 DLCI 101, IP, length 84: IP (tos 0x0, ttl  64, id 6 ...
-- 
Krzysztof Halasa, B*FH

Attachment: print-fr.diff
Description: