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#include <sys/cdefs.h>
25#ifndef lint
26__RCSID("$NetBSD: print-pppoe.c,v 1.8 2023/08/17 20:19:40 christos Exp $");
27#endif
28
29/* \summary: PPP-over-Ethernet (PPPoE) printer */
30
31#ifdef HAVE_CONFIG_H
32#include <config.h>
33#endif
34
35#include "netdissect-stdinc.h"
36
37#include "netdissect-ctype.h"
38
39#define ND_LONGJMP_FROM_TCHECK
40#include "netdissect.h"
41#include "extract.h"
42
43/* Codes */
44enum {
45	PPPOE_PADI = 0x09,
46	PPPOE_PADO = 0x07,
47	PPPOE_PADR = 0x19,
48	PPPOE_PADS = 0x65,
49	PPPOE_PADT = 0xa7
50};
51
52static const struct tok pppoecode2str[] = {
53	{ PPPOE_PADI, "PADI" },
54	{ PPPOE_PADO, "PADO" },
55	{ PPPOE_PADR, "PADR" },
56	{ PPPOE_PADS, "PADS" },
57	{ PPPOE_PADT, "PADT" },
58	{ 0, "" }, /* PPP Data */
59	{ 0, NULL }
60};
61
62/* Tags */
63enum {
64	PPPOE_EOL = 0,
65	PPPOE_SERVICE_NAME = 0x0101,
66	PPPOE_AC_NAME = 0x0102,
67	PPPOE_HOST_UNIQ = 0x0103,
68	PPPOE_AC_COOKIE = 0x0104,
69	PPPOE_VENDOR = 0x0105,
70	PPPOE_RELAY_SID = 0x0110,
71	PPPOE_MAX_PAYLOAD = 0x0120,
72	PPPOE_SERVICE_NAME_ERROR = 0x0201,
73	PPPOE_AC_SYSTEM_ERROR = 0x0202,
74	PPPOE_GENERIC_ERROR = 0x0203
75};
76
77static const struct tok pppoetag2str[] = {
78	{ PPPOE_EOL, "EOL" },
79	{ PPPOE_SERVICE_NAME, "Service-Name" },
80	{ PPPOE_AC_NAME, "AC-Name" },
81	{ PPPOE_HOST_UNIQ, "Host-Uniq" },
82	{ PPPOE_AC_COOKIE, "AC-Cookie" },
83	{ PPPOE_VENDOR, "Vendor-Specific" },
84	{ PPPOE_RELAY_SID, "Relay-Session-ID" },
85	{ PPPOE_MAX_PAYLOAD, "PPP-Max-Payload" },
86	{ PPPOE_SERVICE_NAME_ERROR, "Service-Name-Error" },
87	{ PPPOE_AC_SYSTEM_ERROR, "AC-System-Error" },
88	{ PPPOE_GENERIC_ERROR, "Generic-Error" },
89	{ 0, NULL }
90};
91
92#define PPPOE_HDRLEN 6
93#define MAXTAGPRINT 80
94
95void
96pppoe_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
97{
98	ndo->ndo_protocol = "pppoe";
99	ndo->ndo_ll_hdr_len += pppoe_print(ndo, p, h->len);
100}
101
102u_int
103pppoe_print(netdissect_options *ndo, const u_char *bp, u_int length)
104{
105	uint16_t pppoe_ver, pppoe_type, pppoe_code, pppoe_sessionid;
106	u_int pppoe_length;
107	const u_char *pppoe_packet, *pppoe_payload;
108
109	ndo->ndo_protocol = "pppoe";
110	if (length < PPPOE_HDRLEN) {
111		ND_PRINT(" (length %u < %u)", length, PPPOE_HDRLEN);
112		goto invalid;
113	}
114	length -= PPPOE_HDRLEN;
115	pppoe_packet = bp;
116	ND_TCHECK_LEN(pppoe_packet, PPPOE_HDRLEN);
117	pppoe_ver  = (GET_U_1(pppoe_packet) & 0xF0) >> 4;
118	pppoe_type  = (GET_U_1(pppoe_packet) & 0x0F);
119	pppoe_code = GET_U_1(pppoe_packet + 1);
120	pppoe_sessionid = GET_BE_U_2(pppoe_packet + 2);
121	pppoe_length    = GET_BE_U_2(pppoe_packet + 4);
122	pppoe_payload = pppoe_packet + PPPOE_HDRLEN;
123
124	if (pppoe_ver != 1) {
125		ND_PRINT(" [ver %u]",pppoe_ver);
126	}
127	if (pppoe_type != 1) {
128		ND_PRINT(" [type %u]",pppoe_type);
129	}
130
131	ND_PRINT("PPPoE %s", tok2str(pppoecode2str, "PAD-%x", pppoe_code));
132	if (pppoe_code == PPPOE_PADI && pppoe_length > 1484 - PPPOE_HDRLEN) {
133		ND_PRINT(" [len %u!]",pppoe_length);
134	}
135	if (pppoe_length > length) {
136		ND_PRINT(" [len %u > %u!]", pppoe_length, length);
137		pppoe_length = length;
138	}
139	if (pppoe_sessionid) {
140		ND_PRINT(" [ses 0x%x]", pppoe_sessionid);
141	}
142
143	if (pppoe_code) {
144		/* PPP session packets don't contain tags */
145		u_short tag_type = 0xffff, tag_len;
146		const u_char *p = pppoe_payload;
147
148		/*
149		 * loop invariant:
150		 * p points to current tag,
151		 * tag_type is previous tag or 0xffff for first iteration
152		 */
153		while (tag_type && p < pppoe_payload + pppoe_length) {
154			tag_type = GET_BE_U_2(p);
155			tag_len = GET_BE_U_2(p + 2);
156			p += 4;
157			/* p points to tag_value */
158
159			if (tag_len) {
160				unsigned ascii_count = 0, garbage_count = 0;
161				const u_char *v;
162				char tag_str[MAXTAGPRINT];
163				unsigned tag_str_len = 0;
164
165				/* TODO print UTF-8 decoded text */
166				ND_TCHECK_LEN(p, tag_len);
167				for (v = p; v < p + tag_len && tag_str_len < MAXTAGPRINT-1; v++)
168					if (ND_ASCII_ISPRINT(GET_U_1(v))) {
169						tag_str[tag_str_len++] = GET_U_1(v);
170						ascii_count++;
171					} else {
172						tag_str[tag_str_len++] = '.';
173						garbage_count++;
174					}
175				tag_str[tag_str_len] = 0;
176
177				if (ascii_count > garbage_count) {
178					ND_PRINT(" [%s \"%*.*s\"]",
179					       tok2str(pppoetag2str, "TAG-0x%x", tag_type),
180					       (int)tag_str_len,
181					       (int)tag_str_len,
182					       tag_str);
183				} else {
184					/* Print hex, not fast to abuse printf but this doesn't get used much */
185					ND_PRINT(" [%s 0x", tok2str(pppoetag2str, "TAG-0x%x", tag_type));
186					for (v=p; v<p+tag_len; v++) {
187						ND_PRINT("%02X", GET_U_1(v));
188					}
189					ND_PRINT("]");
190				}
191
192
193			} else
194				ND_PRINT(" [%s]", tok2str(pppoetag2str,
195				    "TAG-0x%x", tag_type));
196
197			p += tag_len;
198			/* p points to next tag */
199		}
200		return PPPOE_HDRLEN;
201	} else {
202		/* PPPoE data */
203		ND_PRINT(" ");
204		return (PPPOE_HDRLEN + ppp_print(ndo, pppoe_payload, pppoe_length));
205	}
206	/* NOTREACHED */
207
208invalid:
209	nd_print_invalid(ndo);
210	return 0;
211}
212