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 #define NETDISSECT_REWORKED 23 #ifdef HAVE_CONFIG_H 24 #include "config.h" 25 #endif 26 27 #include <tcpdump-stdinc.h> 28 29 #include "interface.h" 30 #include "slcompress.h" 31 #include "ppp.h" 32 33 /* 34 * XXX - for BSD/OS PPP, what packets get supplied with a PPP header type 35 * of PPP_VJC and what packets get supplied with a PPP header type of 36 * PPP_VJNC? PPP_VJNC is for "UNCOMPRESSED_TCP" packets, and PPP_VJC 37 * is for COMPRESSED_TCP packets (PPP_IP is used for TYPE_IP packets). 38 * 39 * RFC 1144 implies that, on the wire, the packet type is *not* needed 40 * for PPP, as different PPP protocol types can be used; it only needs 41 * to be put on the wire for SLIP. 42 * 43 * It also indicates that, for compressed SLIP: 44 * 45 * If the COMPRESSED_TCP bit is set in the first byte, it's 46 * a COMPRESSED_TCP packet; that byte is the change byte, and 47 * the COMPRESSED_TCP bit, 0x80, isn't used in the change byte. 48 * 49 * If the upper 4 bits of the first byte are 7, it's an 50 * UNCOMPRESSED_TCP packet; that byte is the first byte of 51 * the UNCOMPRESSED_TCP modified IP header, with a connection 52 * number in the protocol field, and with the version field 53 * being 7, not 4. 54 * 55 * Otherwise, the packet is an IPv4 packet (where the upper 4 bits 56 * of the packet are 4). 57 * 58 * So this routine looks as if it's sort-of intended to handle 59 * compressed SLIP, although it doesn't handle UNCOMPRESSED_TCP 60 * correctly for that (it doesn't fix the version number and doesn't 61 * do anything to the protocol field), and doesn't check for COMPRESSED_TCP 62 * packets correctly for that (you only check the first bit - see 63 * B.1 in RFC 1144). 64 * 65 * But it's called for BSD/OS PPP, not SLIP - perhaps BSD/OS does weird 66 * things with the headers? 67 * 68 * Without a BSD/OS VJC-compressed PPP trace, or knowledge of what the 69 * BSD/OS VJC code does, we can't say what's the case. 70 * 71 * We therefore leave "proto" - which is the PPP protocol type - in place, 72 * *not* marked as unused, for now, so that GCC warnings about the 73 * unused argument remind us that we should fix this some day. 74 */ 75 int 76 vjc_print(netdissect_options *ndo, register const char *bp, u_short proto _U_) 77 { 78 int i; 79 80 switch (bp[0] & 0xf0) { 81 case TYPE_IP: 82 if (ndo->ndo_eflag) 83 ND_PRINT((ndo, "(vjc type=IP) ")); 84 return PPP_IP; 85 case TYPE_UNCOMPRESSED_TCP: 86 if (ndo->ndo_eflag) 87 ND_PRINT((ndo, "(vjc type=raw TCP) ")); 88 return PPP_IP; 89 case TYPE_COMPRESSED_TCP: 90 if (ndo->ndo_eflag) 91 ND_PRINT((ndo, "(vjc type=compressed TCP) ")); 92 for (i = 0; i < 8; i++) { 93 if (bp[1] & (0x80 >> i)) 94 ND_PRINT((ndo, "%c", "?CI?SAWU"[i])); 95 } 96 if (bp[1]) 97 ND_PRINT((ndo, " ")); 98 ND_PRINT((ndo, "C=0x%02x ", bp[2])); 99 ND_PRINT((ndo, "sum=0x%04x ", *(u_short *)&bp[3])); 100 return -1; 101 case TYPE_ERROR: 102 if (ndo->ndo_eflag) 103 ND_PRINT((ndo, "(vjc type=error) ")); 104 return -1; 105 default: 106 if (ndo->ndo_eflag) 107 ND_PRINT((ndo, "(vjc type=0x%02x) ", bp[0] & 0xf0)); 108 return -1; 109 } 110 } 111
