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print-pppoe.c

/*
 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 * 
 * Original code by Greg Stark <gsstark@mit.edu> 
 */

#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header: /tcpdump/master/tcpdump/print-pppoe.c,v 1.24.2.4 2004/03/24 03:04:22 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#include <stdio.h>
#include <string.h>

#include "interface.h"
#include "addrtoname.h"
#include "ppp.h"
#include "ethertype.h"
#include "ether.h"
#include "extract.h"                /* must come after interface.h */

/* Codes */
enum {
      PPPOE_PADI = 0x09,
      PPPOE_PADO = 0x07,
      PPPOE_PADR = 0x19,
      PPPOE_PADS = 0x65,
      PPPOE_PADT = 0xa7
};

static struct tok pppoecode2str[] = {
      { PPPOE_PADI, "PADI" },
      { PPPOE_PADO, "PADO" },
      { PPPOE_PADR, "PADR" },
      { PPPOE_PADS, "PADS" },
      { PPPOE_PADT, "PADT" },
      { 0, "" }, /* PPP Data */
      { 0, NULL }
};

/* Tags */
enum {
      PPPOE_EOL = 0,
      PPPOE_SERVICE_NAME = 0x0101,
      PPPOE_AC_NAME = 0x0102,
      PPPOE_HOST_UNIQ = 0x0103,
      PPPOE_AC_COOKIE = 0x0104,
      PPPOE_VENDOR = 0x0105,
      PPPOE_RELAY_SID = 0x0110,
      PPPOE_SERVICE_NAME_ERROR = 0x0201,
      PPPOE_AC_SYSTEM_ERROR = 0x0202,
      PPPOE_GENERIC_ERROR = 0x0203
};

static struct tok pppoetag2str[] = {
      { PPPOE_EOL, "EOL" },
      { PPPOE_SERVICE_NAME, "Service-Name" },
      { PPPOE_AC_NAME, "AC-Name" },
      { PPPOE_HOST_UNIQ, "Host-Uniq" },
      { PPPOE_AC_COOKIE, "AC-Cookie" },
      { PPPOE_VENDOR, "Vendor-Specific" },
      { PPPOE_RELAY_SID, "Relay-Session-ID" },
      { PPPOE_SERVICE_NAME_ERROR, "Service-Name-Error" },
      { PPPOE_AC_SYSTEM_ERROR, "AC-System-Error" },
      { PPPOE_GENERIC_ERROR, "Generic-Error" },
      { 0, NULL }
};

#define PPPOE_HDRLEN 6
#define MAXTAGPRINT 80

u_int
pppoe_if_print(const struct pcap_pkthdr *h, register const u_char *p)
{
      return (pppoe_print(p, h->len));
}

u_int
pppoe_print(register const u_char *bp, u_int length)
{
      u_short pppoe_ver, pppoe_type, pppoe_code, pppoe_sessionid, pppoe_length;
      const u_char *pppoe_packet, *pppoe_payload;

      pppoe_packet = bp;
      TCHECK2(*pppoe_packet, PPPOE_HDRLEN);
      pppoe_ver  = (pppoe_packet[0] & 0xF0) >> 4;
      pppoe_type  = (pppoe_packet[0] & 0x0F);
      pppoe_code = pppoe_packet[1];
      pppoe_sessionid = EXTRACT_16BITS(pppoe_packet + 2);
      pppoe_length    = EXTRACT_16BITS(pppoe_packet + 4);
      pppoe_payload = pppoe_packet + PPPOE_HDRLEN;

      if (snapend < pppoe_payload) {
            printf(" truncated PPPoE");
            return (PPPOE_HDRLEN);
      }

      if (pppoe_ver != 1) {
            printf(" [ver %d]",pppoe_ver);
      }
      if (pppoe_type != 1) {
            printf(" [type %d]",pppoe_type);
      }

      printf("PPPoE %s", tok2str(pppoecode2str, "PAD-%x", pppoe_code));
      if (pppoe_code == PPPOE_PADI && pppoe_length > 1484 - PPPOE_HDRLEN) {
            printf(" [len %d!]",pppoe_length);
      }
      if (pppoe_sessionid) {
            printf(" [ses 0x%x]", pppoe_sessionid);
      }

      if (pppoe_payload + pppoe_length < snapend && snapend-pppoe_payload+14 > 64) {
            /* (small packets are probably just padded up to the ethernet
               minimum of 64 bytes) */
            printf(" [length %d (%d extra bytes)]",
                pppoe_length, snapend - pppoe_payload - pppoe_length);
#if RESPECT_PAYLOAD_LENGTH
            snapend = pppoe_payload+pppoe_length;
#else
            /* Actual PPPoE implementations appear to ignore the payload
               length and use the full ethernet frame anyways */
            pppoe_length = snapend-pppoe_payload;
#endif
            
      }

      if (pppoe_code) {
            /* PPP session packets don't contain tags */
            u_short tag_type = 0xffff, tag_len;
            const u_char *p = pppoe_payload;

            /*
             * loop invariant:
             * p points to next tag,
             * tag_type is previous tag or 0xffff for first iteration
             */
            while (tag_type && p + 4 < pppoe_payload + length &&
                p + 4 < snapend) {
                  tag_type = EXTRACT_16BITS(p);
                  tag_len = EXTRACT_16BITS(p + 2);
                  p += 4;
                  /* p points to tag_value */

                  if (tag_len) {
                        unsigned isascii = 0, isgarbage = 0;
                        const u_char *v = p;
                        char tag_str[MAXTAGPRINT];
                        unsigned tag_str_len = 0;

                        /* TODO print UTF-8 decoded text */
                        for (v = p; v < p + tag_len && tag_str_len < MAXTAGPRINT-1; v++)
                              if (*v >= 32 && *v < 127) {
                                    tag_str[tag_str_len++] = *v;
                                    isascii++;
                              } else {
                                    tag_str[tag_str_len++] = '.';
                                    isgarbage++;
                              }
                        tag_str[tag_str_len] = 0;

                        if (isascii > isgarbage) {
                              printf(" [%s \"%*.*s\"]",
                                     tok2str(pppoetag2str, "TAG-0x%x", tag_type),
                                     (int)tag_str_len,
                                     (int)tag_str_len,
                                     tag_str);
                        } else {
                              /* Print hex, not fast to abuse printf but this doesn't get used much */
                              printf(" [%s 0x", tok2str(pppoetag2str, "TAG-0x%x", tag_type));
                              for (v=p; v<p+tag_len; v++) {
                                    printf("%02X", *v);
                              }
                              printf("]");
                        }
                        

                  } else
                        printf(" [%s]", tok2str(pppoetag2str,
                            "TAG-0x%x", tag_type));

                  p += tag_len;
                  /* p points to next tag */
            }
            return (0);
      } else {
            /* PPPoE data */
            printf(" ");
            return (PPPOE_HDRLEN + ppp_print(pppoe_payload, pppoe_length));
      }

trunc:
      printf("[|pppoe]");
      return (PPPOE_HDRLEN);
}

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