/*
* 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 <[email protected]>
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-pppoe.c,v 1.9 2024/09/02 16:15:32 christos Exp $");
#endif

/* \summary: PPP-over-Ethernet (PPPoE) printer */

#include <config.h>

#include "netdissect-stdinc.h"

#include "netdissect-ctype.h"

#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "extract.h"

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

static const 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_MAX_PAYLOAD = 0x0120,
       PPPOE_SERVICE_NAME_ERROR = 0x0201,
       PPPOE_AC_SYSTEM_ERROR = 0x0202,
       PPPOE_GENERIC_ERROR = 0x0203
};

static const 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_MAX_PAYLOAD, "PPP-Max-Payload" },
       { 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

void
pppoe_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
{
       ndo->ndo_protocol = "pppoe";
       ndo->ndo_ll_hdr_len += pppoe_print(ndo, p, h->len);
}

u_int
pppoe_print(netdissect_options *ndo, const u_char *bp, u_int length)
{
       uint16_t pppoe_ver, pppoe_type, pppoe_code, pppoe_sessionid;
       u_int pppoe_length;
       const u_char *pppoe_packet, *pppoe_payload;

       ndo->ndo_protocol = "pppoe";
       if (length < PPPOE_HDRLEN) {
               ND_PRINT(" (length %u < %u)", length, PPPOE_HDRLEN);
               goto invalid;
       }
       length -= PPPOE_HDRLEN;
       pppoe_packet = bp;
       ND_TCHECK_LEN(pppoe_packet, PPPOE_HDRLEN);
       pppoe_ver  = (GET_U_1(pppoe_packet) & 0xF0) >> 4;
       pppoe_type  = (GET_U_1(pppoe_packet) & 0x0F);
       pppoe_code = GET_U_1(pppoe_packet + 1);
       pppoe_sessionid = GET_BE_U_2(pppoe_packet + 2);
       pppoe_length    = GET_BE_U_2(pppoe_packet + 4);
       pppoe_payload = pppoe_packet + PPPOE_HDRLEN;

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

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

       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 current tag,
                * tag_type is previous tag or 0xffff for first iteration
                */
               while (tag_type && p < pppoe_payload + pppoe_length) {
                       tag_type = GET_BE_U_2(p);
                       tag_len = GET_BE_U_2(p + 2);
                       p += 4;
                       /* p points to tag_value */

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

                               /* TODO print UTF-8 decoded text */
                               ND_TCHECK_LEN(p, tag_len);
                               for (v = p; v < p + tag_len && tag_str_len < MAXTAGPRINT-1; v++)
                                       if (ND_ASCII_ISPRINT(GET_U_1(v))) {
                                               tag_str[tag_str_len++] = GET_U_1(v);
                                               ascii_count++;
                                       } else {
                                               tag_str[tag_str_len++] = '.';
                                               garbage_count++;
                                       }
                               tag_str[tag_str_len] = 0;

                               if (ascii_count > garbage_count) {
                                       ND_PRINT(" [%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 */
                                       ND_PRINT(" [%s 0x", tok2str(pppoetag2str, "TAG-0x%x", tag_type));
                                       for (v=p; v<p+tag_len; v++) {
                                               ND_PRINT("%02X", GET_U_1(v));
                                       }
                                       ND_PRINT("]");
                               }


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

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

invalid:
       nd_print_invalid(ndo);
       return 0;
}

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