diff options
Diffstat (limited to 'print-cdp.c')
| -rw-r--r-- | print-cdp.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/print-cdp.c b/print-cdp.c new file mode 100644 index 0000000..9f5c24b --- /dev/null +++ b/print-cdp.c @@ -0,0 +1,472 @@ +/* + * Copyright (c) 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. + * + * Code by Gert Doering, SpaceNet GmbH, gert@space.net + * + * Reference documentation: + * https://web.archive.org/web/20000914194913/http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.pdf + */ + +/* \summary: Cisco Discovery Protocol (CDP) printer */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include "netdissect-stdinc.h" + +#include <string.h> + +#define ND_LONGJMP_FROM_TCHECK +#include "netdissect.h" +#include "addrtoname.h" +#include "extract.h" +#include "nlpid.h" + + +#define CDP_HEADER_LEN 4 +#define CDP_HEADER_VERSION_OFFSET 0 +#define CDP_HEADER_TTL_OFFSET 1 +#define CDP_HEADER_CHECKSUM_OFFSET 2 + +#define CDP_TLV_HEADER_LEN 4 +#define CDP_TLV_TYPE_OFFSET 0 +#define CDP_TLV_LEN_OFFSET 2 + +static const struct tok cdp_capability_values[] = { + { 0x01, "Router" }, + { 0x02, "Transparent Bridge" }, + { 0x04, "Source Route Bridge" }, + { 0x08, "L2 Switch" }, + { 0x10, "L3 capable" }, + { 0x20, "IGMP snooping" }, + { 0x40, "L1 capable" }, + { 0, NULL } +}; + +static void cdp_print_addr(netdissect_options *, const u_char *, u_int); +static void cdp_print_prefixes(netdissect_options *, const u_char *, u_int); + +static void +cdp_print_string(netdissect_options *ndo, + const u_char *cp, const u_int len) +{ + ND_PRINT("'"); + (void)nd_printn(ndo, cp, len, NULL); + ND_PRINT("'"); +} + +static void +cdp_print_power(netdissect_options *ndo, + const u_char *cp, const u_int len) +{ + u_int val = 0; + + switch (len) { + case 1: + val = GET_U_1(cp); + break; + case 2: + val = GET_BE_U_2(cp); + break; + case 3: + val = GET_BE_U_3(cp); + break; + } + ND_PRINT("%1.2fW", val / 1000.0); +} + +static void +cdp_print_capability(netdissect_options *ndo, + const u_char *cp, const u_int len _U_) +{ + uint32_t val = GET_BE_U_4(cp); + + ND_PRINT("(0x%08x): %s", val, + bittok2str(cdp_capability_values, "none", val)); +} + +/* Rework the version string to get a nice indentation. */ +static void +cdp_print_version(netdissect_options *ndo, + const u_char *cp, const u_int len) +{ + unsigned i; + + ND_PRINT("\n\t "); + for (i = 0; i < len; i++) { + u_char c = GET_U_1(cp + i); + + if (c == '\n') + ND_PRINT("\n\t "); + else + fn_print_char(ndo, c); + } +} + +static void +cdp_print_uint16(netdissect_options *ndo, + const u_char *cp, const u_int len _U_) +{ + ND_PRINT("%u", GET_BE_U_2(cp)); +} + +static void +cdp_print_duplex(netdissect_options *ndo, + const u_char *cp, const u_int len _U_) +{ + ND_PRINT("%s", GET_U_1(cp) ? "full": "half"); +} + +/* https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cata/186/2_12_m/english/release/notes/186rn21m.html +* plus more details from other sources +* +* There are apparently versions of the request with both +* 2 bytes and 3 bytes of value. The 3 bytes of value +* appear to be a 1-byte application type followed by a +* 2-byte VLAN ID; the 2 bytes of value are unknown +* (they're 0x20 0x00 in some captures I've seen; that +* is not a valid VLAN ID, as VLAN IDs are 12 bits). +* +* The replies all appear to be 3 bytes long. +*/ +static void +cdp_print_ata186(netdissect_options *ndo, + const u_char *cp, const u_int len) +{ + if (len == 2) + ND_PRINT("unknown 0x%04x", GET_BE_U_2(cp)); + else + ND_PRINT("app %u, vlan %u", GET_U_1(cp), GET_BE_U_2(cp + 1)); +} + +static void +cdp_print_mtu(netdissect_options *ndo, + const u_char *cp, const u_int len _U_) +{ + ND_PRINT("%u bytes", GET_BE_U_4(cp)); +} + +static void +cdp_print_uint8x(netdissect_options *ndo, + const u_char *cp, const u_int len _U_) +{ + ND_PRINT("0x%02x", GET_U_1(cp)); +} + +static void +cdp_print_phys_loc(netdissect_options *ndo, + const u_char *cp, const u_int len) +{ + ND_PRINT("0x%02x", GET_U_1(cp)); + if (len > 1) { + ND_PRINT("/"); + (void)nd_printn(ndo, cp + 1, len - 1, NULL); + } +} + +struct cdp_tlvinfo { + const char *name; + void (*printer)(netdissect_options *ndo, const u_char *, u_int); + int min_len, max_len; +}; + +#define T_DEV_ID 0x01 +#define T_MAX 0x17 +static const struct cdp_tlvinfo cdptlvs[T_MAX + 1] = { + /* 0x00 */ + [ T_DEV_ID ] = { "Device-ID", cdp_print_string, -1, -1 }, + [ 0x02 ] = { "Address", cdp_print_addr, -1, -1 }, + [ 0x03 ] = { "Port-ID", cdp_print_string, -1, -1 }, + [ 0x04 ] = { "Capability", cdp_print_capability, 4, 4 }, + [ 0x05 ] = { "Version String", cdp_print_version, -1, -1 }, + [ 0x06 ] = { "Platform", cdp_print_string, -1, -1 }, + [ 0x07 ] = { "Prefixes", cdp_print_prefixes, -1, -1 }, + /* not documented */ + [ 0x08 ] = { "Protocol-Hello option", NULL, -1, -1 }, + /* CDPv2 */ + [ 0x09 ] = { "VTP Management Domain", cdp_print_string, -1, -1 }, + /* CDPv2 */ + [ 0x0a ] = { "Native VLAN ID", cdp_print_uint16, 2, 2 }, + /* CDPv2 */ + [ 0x0b ] = { "Duplex", cdp_print_duplex, 1, 1 }, + /* 0x0c */ + /* 0x0d */ + /* incomplete doc. */ + [ 0x0e ] = { "ATA-186 VoIP VLAN assignment", cdp_print_ata186, 3, 3 }, + /* incomplete doc. */ + [ 0x0f ] = { "ATA-186 VoIP VLAN request", cdp_print_ata186, 2, 3 }, + /* not documented */ + [ 0x10 ] = { "power consumption", cdp_print_power, 1, 3 }, + /* not documented */ + [ 0x11 ] = { "MTU", cdp_print_mtu, 4, 4 }, + /* not documented */ + [ 0x12 ] = { "AVVID trust bitmap", cdp_print_uint8x, 1, 1 }, + /* not documented */ + [ 0x13 ] = { "AVVID untrusted ports CoS", cdp_print_uint8x, 1, 1 }, + /* not documented */ + [ 0x14 ] = { "System Name", cdp_print_string, -1, -1 }, + /* not documented */ + [ 0x15 ] = { "System Object ID (not decoded)", NULL, -1, -1 }, + [ 0x16 ] = { "Management Addresses", cdp_print_addr, 4, -1 }, + /* not documented */ + [ 0x17 ] = { "Physical Location", cdp_print_phys_loc, 1, -1 }, +}; + +void +cdp_print(netdissect_options *ndo, + const u_char *tptr, u_int length) +{ + u_int orig_length = length; + uint16_t checksum; + + ndo->ndo_protocol = "cdp"; + + if (length < CDP_HEADER_LEN) { + ND_PRINT(" (packet length %u < %u)", length, CDP_HEADER_LEN); + goto invalid; + } + ND_PRINT("CDPv%u, ttl: %us", + GET_U_1(tptr + CDP_HEADER_VERSION_OFFSET), + GET_U_1(tptr + CDP_HEADER_TTL_OFFSET)); + checksum = GET_BE_U_2(tptr + CDP_HEADER_CHECKSUM_OFFSET); + if (ndo->ndo_vflag) + ND_PRINT(", checksum: 0x%04x (unverified), length %u", + checksum, orig_length); + tptr += CDP_HEADER_LEN; + length -= CDP_HEADER_LEN; + + while (length) { + u_int type, len; + const struct cdp_tlvinfo *info; + const char *name; + u_char covered = 0; + + if (length < CDP_TLV_HEADER_LEN) { + ND_PRINT(" (remaining packet length %u < %u)", + length, CDP_TLV_HEADER_LEN); + goto invalid; + } + type = GET_BE_U_2(tptr + CDP_TLV_TYPE_OFFSET); + len = GET_BE_U_2(tptr + CDP_TLV_LEN_OFFSET); /* object length includes the 4 bytes header length */ + info = type <= T_MAX ? &cdptlvs[type] : NULL; + name = (info && info->name) ? info->name : "unknown field type"; + if (len < CDP_TLV_HEADER_LEN) { + if (ndo->ndo_vflag) + ND_PRINT("\n\t%s (0x%02x), TLV length: %u byte%s (too short)", + name, type, len, PLURAL_SUFFIX(len)); + else + ND_PRINT(", %s TLV length %u too short", + name, len); + goto invalid; + } + if (len > length) { + ND_PRINT(" (TLV length %u > %u)", len, length); + goto invalid; + } + tptr += CDP_TLV_HEADER_LEN; + length -= CDP_TLV_HEADER_LEN; + len -= CDP_TLV_HEADER_LEN; + + /* In non-verbose mode just print Device-ID. */ + if (!ndo->ndo_vflag && type == T_DEV_ID) + ND_PRINT(", Device-ID "); + else if (ndo->ndo_vflag) + ND_PRINT("\n\t%s (0x%02x), value length: %u byte%s: ", + name, type, len, PLURAL_SUFFIX(len)); + + if (info) { + if ((info->min_len > 0 && len < (unsigned)info->min_len) || + (info->max_len > 0 && len > (unsigned)info->max_len)) + ND_PRINT(" (malformed TLV)"); + else if (ndo->ndo_vflag || type == T_DEV_ID) { + if (info->printer) + info->printer(ndo, tptr, len); + else + ND_TCHECK_LEN(tptr, len); + /* + * When the type is defined without a printer, + * do not print the hex dump. + */ + covered = 1; + } + } + + if (!covered) { + ND_TCHECK_LEN(tptr, len); + print_unknown_data(ndo, tptr, "\n\t ", len); + } + tptr += len; + length -= len; + } + if (ndo->ndo_vflag < 1) + ND_PRINT(", length %u", orig_length); + + return; +invalid: + nd_print_invalid(ndo); + ND_TCHECK_LEN(tptr, length); +} + +/* + * Protocol type values. + * + * PT_NLPID means that the protocol type field contains an OSI NLPID. + * + * PT_IEEE_802_2 means that the protocol type field contains an IEEE 802.2 + * LLC header that specifies that the payload is for that protocol. + */ +#define PT_NLPID 1 /* OSI NLPID */ +#define PT_IEEE_802_2 2 /* IEEE 802.2 LLC header */ + +static void +cdp_print_addr(netdissect_options *ndo, + const u_char * p, u_int l) +{ + u_int num; + static const u_char prot_ipv6[] = { + 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00, 0x86, 0xdd + }; + + if (l < 4) { + ND_PRINT(" (not enough space for num)"); + goto invalid; + } + num = GET_BE_U_4(p); + p += 4; + l -= 4; + + while (num) { + u_int pt, pl, al; + + if (l < 2) { + ND_PRINT(" (not enough space for PT+PL)"); + goto invalid; + } + pt = GET_U_1(p); /* type of "protocol" field */ + pl = GET_U_1(p + 1); /* length of "protocol" field */ + p += 2; + l -= 2; + + if (l < pl + 2) { + ND_PRINT(" (not enough space for P+AL)"); + goto invalid; + } + /* Skip the protocol for now. */ + al = GET_BE_U_2(p + pl); /* address length */ + + if (pt == PT_NLPID && pl == 1 && GET_U_1(p) == NLPID_IP && + al == 4) { + /* + * IPv4: protocol type = NLPID, protocol length = 1 + * (1-byte NLPID), protocol = 0xcc (NLPID for IPv4), + * address length = 4 + */ + p += pl + 2; + l -= pl + 2; + /* p is just beyond al now. */ + if (l < al) { + ND_PRINT(" (not enough space for A)"); + goto invalid; + } + ND_PRINT("IPv4 (%u) %s", num, GET_IPADDR_STRING(p)); + p += al; + l -= al; + } + else if (pt == PT_IEEE_802_2 && pl == 8 && + memcmp(p, prot_ipv6, 8) == 0 && al == 16) { + /* + * IPv6: protocol type = IEEE 802.2 header, + * protocol length = 8 (size of LLC+SNAP header), + * protocol = LLC+SNAP header with the IPv6 + * Ethertype, address length = 16 + */ + p += pl + 2; + l -= pl + 2; + /* p is just beyond al now. */ + if (l < al) { + ND_PRINT(" (not enough space for A)"); + goto invalid; + } + ND_PRINT("IPv6 (%u) %s", num, GET_IP6ADDR_STRING(p)); + p += al; + l -= al; + } + else { + /* + * Generic case: just print raw data + */ + ND_PRINT("pt=0x%02x, pl=%u, pb=", pt, pl); + while (pl != 0) { + ND_PRINT(" %02x", GET_U_1(p)); + p++; + l--; + pl--; + } + ND_PRINT(", al=%u, a=", al); + p += 2; + l -= 2; + /* p is just beyond al now. */ + if (l < al) { + ND_PRINT(" (not enough space for A)"); + goto invalid; + } + while (al != 0) { + ND_PRINT(" %02x", GET_U_1(p)); + p++; + l--; + al--; + } + } + num--; + if (num) + ND_PRINT(" "); + } + if (l) + ND_PRINT(" (%u bytes of stray data)", l); + return; + +invalid: + ND_TCHECK_LEN(p, l); +} + +static void +cdp_print_prefixes(netdissect_options *ndo, + const u_char * p, u_int l) +{ + if (l % 5) { + ND_PRINT(" [length %u is not a multiple of 5]", l); + goto invalid; + } + + ND_PRINT(" IPv4 Prefixes (%u):", l / 5); + + while (l > 0) { + ND_PRINT(" %u.%u.%u.%u/%u", + GET_U_1(p), GET_U_1(p + 1), GET_U_1(p + 2), + GET_U_1(p + 3), GET_U_1(p + 4)); + l -= 5; + p += 5; + } + return; + +invalid: + ND_TCHECK_LEN(p, l); +} |