The Tcpdump Group git mirrors - tcpdump/blob - print-pppoe.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 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  * Original code by Greg Stark <gsstark@mit.edu>
  22  */
  23
  24 /* \summary: PPP-over-Ethernet (PPPoE) printer */
  25
  26 #ifdef HAVE_CONFIG_H
  27 #include <config.h>
  28 #endif
  29
  30 #include "netdissect-stdinc.h"
  31
  32 #include "netdissect-ctype.h"
  33
  34 #include "netdissect.h"
  35 #include "extract.h"
  36
  37 /* Codes */
  38 enum {
  39         PPPOE_PADI = 0x09,
  40         PPPOE_PADO = 0x07,
  41         PPPOE_PADR = 0x19,
  42         PPPOE_PADS = 0x65,
  43         PPPOE_PADT = 0xa7
  44 };
  45
  46 static const struct tok pppoecode2str[] = {
  47         { PPPOE_PADI, "PADI" },
  48         { PPPOE_PADO, "PADO" },
  49         { PPPOE_PADR, "PADR" },
  50         { PPPOE_PADS, "PADS" },
  51         { PPPOE_PADT, "PADT" },
  52         { 0, "" }, /* PPP Data */
  53         { 0, NULL }
  54 };
  55
  56 /* Tags */
  57 enum {
  58         PPPOE_EOL = 0,
  59         PPPOE_SERVICE_NAME = 0x0101,
  60         PPPOE_AC_NAME = 0x0102,
  61         PPPOE_HOST_UNIQ = 0x0103,
  62         PPPOE_AC_COOKIE = 0x0104,
  63         PPPOE_VENDOR = 0x0105,
  64         PPPOE_RELAY_SID = 0x0110,
  65         PPPOE_MAX_PAYLOAD = 0x0120,
  66         PPPOE_SERVICE_NAME_ERROR = 0x0201,
  67         PPPOE_AC_SYSTEM_ERROR = 0x0202,
  68         PPPOE_GENERIC_ERROR = 0x0203
  69 };
  70
  71 static const struct tok pppoetag2str[] = {
  72         { PPPOE_EOL, "EOL" },
  73         { PPPOE_SERVICE_NAME, "Service-Name" },
  74         { PPPOE_AC_NAME, "AC-Name" },
  75         { PPPOE_HOST_UNIQ, "Host-Uniq" },
  76         { PPPOE_AC_COOKIE, "AC-Cookie" },
  77         { PPPOE_VENDOR, "Vendor-Specific" },
  78         { PPPOE_RELAY_SID, "Relay-Session-ID" },
  79         { PPPOE_MAX_PAYLOAD, "PPP-Max-Payload" },
  80         { PPPOE_SERVICE_NAME_ERROR, "Service-Name-Error" },
  81         { PPPOE_AC_SYSTEM_ERROR, "AC-System-Error" },
  82         { PPPOE_GENERIC_ERROR, "Generic-Error" },
  83         { 0, NULL }
  84 };
  85
  86 #define PPPOE_HDRLEN 6
  87 #define MAXTAGPRINT 80
  88
  89 void
  90 pppoe_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
  91 {
  92         ndo->ndo_protocol = "pppoe";
  93         ndo->ndo_ll_hdr_len += pppoe_print(ndo, p, h->len);
  94 }
  95
  96 u_int
  97 pppoe_print(netdissect_options *ndo, const u_char *bp, u_int length)
  98 {
  99         uint16_t pppoe_ver, pppoe_type, pppoe_code, pppoe_sessionid;
 100         u_int pppoe_length, caplen;
 101         const u_char *pppoe_packet, *pppoe_payload;
 102
 103         ndo->ndo_protocol = "pppoe";
 104         caplen = ndo->ndo_snapend - bp;
 105         if (caplen < PPPOE_HDRLEN) {
 106                 nd_print_trunc(ndo);
 107                 return caplen;
 108         }
 109         if (length < PPPOE_HDRLEN) {
 110                 nd_print_trunc(ndo);
 111                 return length;
 112         }
 113         length -= PPPOE_HDRLEN;
 114         pppoe_packet = bp;
 115         ND_TCHECK_LEN(pppoe_packet, PPPOE_HDRLEN);
 116         pppoe_ver  = (GET_U_1(pppoe_packet) & 0xF0) >> 4;
 117         pppoe_type  = (GET_U_1(pppoe_packet) & 0x0F);
 118         pppoe_code = GET_U_1(pppoe_packet + 1);
 119         pppoe_sessionid = GET_BE_U_2(pppoe_packet + 2);
 120         pppoe_length    = GET_BE_U_2(pppoe_packet + 4);
 121         pppoe_payload = pppoe_packet + PPPOE_HDRLEN;
 122
 123         if (pppoe_ver != 1) {
 124                 ND_PRINT(" [ver %u]",pppoe_ver);
 125         }
 126         if (pppoe_type != 1) {
 127                 ND_PRINT(" [type %u]",pppoe_type);
 128         }
 129
 130         ND_PRINT("PPPoE %s", tok2str(pppoecode2str, "PAD-%x", pppoe_code));
 131         if (pppoe_code == PPPOE_PADI && pppoe_length > 1484 - PPPOE_HDRLEN) {
 132                 ND_PRINT(" [len %u!]",pppoe_length);
 133         }
 134         if (pppoe_length > length) {
 135                 ND_PRINT(" [len %u > %u!]", pppoe_length, length);
 136                 pppoe_length = length;
 137         }
 138         if (pppoe_sessionid) {
 139                 ND_PRINT(" [ses 0x%x]", pppoe_sessionid);
 140         }
 141
 142         if (pppoe_code) {
 143                 /* PPP session packets don't contain tags */
 144                 u_short tag_type = 0xffff, tag_len;
 145                 const u_char *p = pppoe_payload;
 146
 147                 /*
 148                  * loop invariant:
 149                  * p points to current tag,
 150                  * tag_type is previous tag or 0xffff for first iteration
 151                  */
 152                 while (tag_type && p < pppoe_payload + pppoe_length) {
 153                         tag_type = GET_BE_U_2(p);
 154                         tag_len = GET_BE_U_2(p + 2);
 155                         p += 4;
 156                         /* p points to tag_value */
 157
 158                         if (tag_len) {
 159                                 unsigned ascii_count = 0, garbage_count = 0;
 160                                 const u_char *v;
 161                                 char tag_str[MAXTAGPRINT];
 162                                 unsigned tag_str_len = 0;
 163
 164                                 /* TODO print UTF-8 decoded text */
 165                                 ND_TCHECK_LEN(p, tag_len);
 166                                 for (v = p; v < p + tag_len && tag_str_len < MAXTAGPRINT-1; v++)
 167                                         if (ND_ASCII_ISPRINT(GET_U_1(v))) {
 168                                                 tag_str[tag_str_len++] = GET_U_1(v);
 169                                                 ascii_count++;
 170                                         } else {
 171                                                 tag_str[tag_str_len++] = '.';
 172                                                 garbage_count++;
 173                                         }
 174                                 tag_str[tag_str_len] = 0;
 175
 176                                 if (ascii_count > garbage_count) {
 177                                         ND_PRINT(" [%s \"%*.*s\"]",
 178                                                tok2str(pppoetag2str, "TAG-0x%x", tag_type),
 179                                                (int)tag_str_len,
 180                                                (int)tag_str_len,
 181                                                tag_str);
 182                                 } else {
 183                                         /* Print hex, not fast to abuse printf but this doesn't get used much */
 184                                         ND_PRINT(" [%s 0x", tok2str(pppoetag2str, "TAG-0x%x", tag_type));
 185                                         for (v=p; v<p+tag_len; v++) {
 186                                                 ND_PRINT("%02X", GET_U_1(v));
 187                                         }
 188                                         ND_PRINT("]");
 189                                 }
 190
 191
 192                         } else
 193                                 ND_PRINT(" [%s]", tok2str(pppoetag2str,
 194                                     "TAG-0x%x", tag_type));
 195
 196                         p += tag_len;
 197                         /* p points to next tag */
 198                 }
 199                 return PPPOE_HDRLEN;
 200         } else {
 201                 /* PPPoE data */
 202                 ND_PRINT(" ");
 203                 return (PPPOE_HDRLEN + ppp_print(ndo, pppoe_payload, pppoe_length));
 204         }
 205
 206 trunc:
 207         nd_print_trunc(ndo);
 208         return PPPOE_HDRLEN;
 209 }