1 /* 2 * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that: (1) source code distributions 7 * retain the above copyright notice and this paragraph in its entirety, (2) 8 * distributions including binary code include the above copyright notice and 9 * this paragraph in its entirety in the documentation or other materials 10 * provided with the distribution, and (3) all advertising materials mentioning 11 * features or use of this software display the following acknowledgement: 12 * ``This product includes software developed by the University of California, 13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 14 * the University nor the names of its contributors may be used to endorse 15 * or promote products derived from this software without specific prior 16 * written permission. 17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 20 */ 21 22 #ifdef HAVE_CONFIG_H 23 #include "config.h" 24 #endif 25 26 #ifndef lint 27 static const char rcsid[] _U_ = 28 "@(#) $Header: /tcpdump/master/tcpdump/print-vjc.c,v 1.15 2004-03-25 03:31:17 mcr Exp $ (LBL)"; 29 #endif 30 31 #include <tcpdump-stdinc.h> 32 33 #include <pcap.h> 34 #include <stdio.h> 35 36 #include "interface.h" 37 #include "addrtoname.h" 38 39 #include "slcompress.h" 40 #include "ppp.h" 41 42 /* 43 * XXX - for BSD/OS PPP, what packets get supplied with a PPP header type 44 * of PPP_VJC and what packets get supplied with a PPP header type of 45 * PPP_VJNC? PPP_VJNC is for "UNCOMPRESSED_TCP" packets, and PPP_VJC 46 * is for COMPRESSED_TCP packets (PPP_IP is used for TYPE_IP packets). 47 * 48 * RFC 1144 implies that, on the wire, the packet type is *not* needed 49 * for PPP, as different PPP protocol types can be used; it only needs 50 * to be put on the wire for SLIP. 51 * 52 * It also indicates that, for compressed SLIP: 53 * 54 * If the COMPRESSED_TCP bit is set in the first byte, it's 55 * a COMPRESSED_TCP packet; that byte is the change byte, and 56 * the COMPRESSED_TCP bit, 0x80, isn't used in the change byte. 57 * 58 * If the upper 4 bits of the first byte are 7, it's an 59 * UNCOMPRESSED_TCP packet; that byte is the first byte of 60 * the UNCOMPRESSED_TCP modified IP header, with a connection 61 * number in the protocol field, and with the version field 62 * being 7, not 4. 63 * 64 * Otherwise, the packet is an IPv4 packet (where the upper 4 bits 65 * of the packet are 4). 66 * 67 * So this routine looks as if it's sort-of intended to handle 68 * compressed SLIP, although it doesn't handle UNCOMPRESSED_TCP 69 * correctly for that (it doesn't fix the version number and doesn't 70 * do anything to the protocol field), and doesn't check for COMPRESSED_TCP 71 * packets correctly for that (you only check the first bit - see 72 * B.1 in RFC 1144). 73 * 74 * But it's called for BSD/OS PPP, not SLIP - perhaps BSD/OS does weird 75 * things with the headers? 76 * 77 * Without a BSD/OS VJC-compressed PPP trace, or knowledge of what the 78 * BSD/OS VJC code does, we can't say what's the case. 79 * 80 * We therefore leave "proto" - which is the PPP protocol type - in place, 81 * *not* marked as unused, for now, so that GCC warnings about the 82 * unused argument remind us that we should fix this some day. 83 */ 84 int 85 vjc_print(register const char *bp, u_short proto _U_) 86 { 87 int i; 88 89 switch (bp[0] & 0xf0) { 90 case TYPE_IP: 91 if (eflag) 92 printf("(vjc type=IP) "); 93 return PPP_IP; 94 case TYPE_UNCOMPRESSED_TCP: 95 if (eflag) 96 printf("(vjc type=raw TCP) "); 97 return PPP_IP; 98 case TYPE_COMPRESSED_TCP: 99 if (eflag) 100 printf("(vjc type=compressed TCP) "); 101 for (i = 0; i < 8; i++) { 102 if (bp[1] & (0x80 >> i)) 103 printf("%c", "?CI?SAWU"[i]); 104 } 105 if (bp[1]) 106 printf(" "); 107 printf("C=0x%02x ", bp[2]); 108 printf("sum=0x%04x ", *(u_short *)&bp[3]); 109 return -1; 110 case TYPE_ERROR: 111 if (eflag) 112 printf("(vjc type=error) "); 113 return -1; 114 default: 115 if (eflag) 116 printf("(vjc type=0x%02x) ", bp[0] & 0xf0); 117 return -1; 118 } 119 } 120