* Copyright (c) 2000 Lennert Buytenhek

/*
* Copyright (c) 2000 Lennert Buytenhek
*
* This software may be distributed either under the terms of the
* BSD-style license that accompanies tcpdump or the GNU General
* Public License
*
* Contributed by Lennert Buytenhek <[email protected]>
*/

/* \summary: IEEE 802.1d Spanning Tree Protocol (STP) printer */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-stp.c,v 1.10 2024/09/02 16:15:33 christos Exp $");
#endif

#include <config.h>

#include "netdissect-stdinc.h"

#include <stdio.h>

#include "netdissect.h"
#include "extract.h"

#define RSTP_EXTRACT_PORT_ROLE(x) (((x)&0x0C)>>2)
/* STP timers are expressed in multiples of 1/256th second */
#define STP_TIME_BASE 256
#define STP_BPDU_MSTP_MIN_LEN 102

struct stp_bpdu_ {
nd_uint16_t protocol_id;
nd_uint8_t protocol_version;
nd_uint8_t bpdu_type;
nd_uint8_t flags;
nd_byte root_id[8];
nd_uint32_t root_path_cost;
nd_byte bridge_id[8];
nd_uint16_t port_id;
nd_uint16_t message_age;
nd_uint16_t max_age;
nd_uint16_t hello_time;
nd_uint16_t forward_delay;
nd_uint8_t v1_length;
};

#define STP_PROTO_REGULAR 0x00
#define STP_PROTO_RAPID 0x02
#define STP_PROTO_MSTP 0x03
#define STP_PROTO_SPB 0x04

static const struct tok stp_proto_values[] = {
{ STP_PROTO_REGULAR, "802.1d" },
{ STP_PROTO_RAPID, "802.1w" },
{ STP_PROTO_MSTP, "802.1s" },
{ STP_PROTO_SPB, "802.1aq" },
{ 0, NULL}
};

#define STP_BPDU_TYPE_CONFIG 0x00
#define STP_BPDU_TYPE_RSTP 0x02
#define STP_BPDU_TYPE_TOPO_CHANGE 0x80

static const struct tok stp_bpdu_flag_values[] = {
{ 0x01, "Topology change" },
{ 0x02, "Proposal" },
{ 0x10, "Learn" },
{ 0x20, "Forward" },
{ 0x40, "Agreement" },
{ 0x80, "Topology change ACK" },
{ 0, NULL}
};

static const struct tok stp_bpdu_type_values[] = {
{ STP_BPDU_TYPE_CONFIG, "Config" },
{ STP_BPDU_TYPE_RSTP, "Rapid STP" },
{ STP_BPDU_TYPE_TOPO_CHANGE, "Topology Change" },
{ 0, NULL}
};

static const struct tok rstp_obj_port_role_values[] = {
{ 0x00, "Unknown" },
{ 0x01, "Alternate" },
{ 0x02, "Root" },
{ 0x03, "Designated" },
{ 0, NULL}
};

static char *
stp_print_bridge_id(netdissect_options *ndo, const u_char *p)
{
static char bridge_id_str[sizeof("pppp.aa:bb:cc:dd:ee:ff")];

snprintf(bridge_id_str, sizeof(bridge_id_str),
"%.2x%.2x.%.2x:%.2x:%.2x:%.2x:%.2x:%.2x",
GET_U_1(p), GET_U_1(p + 1), GET_U_1(p + 2),
GET_U_1(p + 3), GET_U_1(p + 4), GET_U_1(p + 5),
GET_U_1(p + 6), GET_U_1(p + 7));

return bridge_id_str;
}

static void
stp_print_config_bpdu(netdissect_options *ndo, const struct stp_bpdu_ *stp_bpdu,
u_int length)
{
uint8_t bpdu_flags;

bpdu_flags = GET_U_1(stp_bpdu->flags);
ND_PRINT(", Flags [%s]",
bittok2str(stp_bpdu_flag_values, "none", bpdu_flags));

ND_PRINT(", bridge-id %s.%04x, length %u",
stp_print_bridge_id(ndo, stp_bpdu->bridge_id),
GET_BE_U_2(stp_bpdu->port_id), length);

/* in non-verbose mode just print the bridge-id */
if (!ndo->ndo_vflag) {
return;
}

ND_PRINT("\n\tmessage-age %.2fs, max-age %.2fs"
", hello-time %.2fs, forwarding-delay %.2fs",
(float) GET_BE_U_2(stp_bpdu->message_age) / STP_TIME_BASE,
(float) GET_BE_U_2(stp_bpdu->max_age) / STP_TIME_BASE,
(float) GET_BE_U_2(stp_bpdu->hello_time) / STP_TIME_BASE,
(float) GET_BE_U_2(stp_bpdu->forward_delay) / STP_TIME_BASE);

ND_PRINT("\n\troot-id %s, root-pathcost %u",
stp_print_bridge_id(ndo, stp_bpdu->root_id),
GET_BE_U_4(stp_bpdu->root_path_cost));

/* Port role is only valid for 802.1w */
if (GET_U_1(stp_bpdu->protocol_version) == STP_PROTO_RAPID) {
ND_PRINT(", port-role %s",
tok2str(rstp_obj_port_role_values, "Unknown",
RSTP_EXTRACT_PORT_ROLE(bpdu_flags)));
}
}

/*
* MSTP packet format
* Ref. IEEE 802.1Q 2003 Ed. Section 14
*
* MSTP BPDU
*
* 2 - bytes Protocol Id
* 1 - byte Protocol Ver.
* 1 - byte BPDU type
* 1 - byte Flags
* 8 - bytes CIST Root Identifier
* 4 - bytes CIST External Path Cost
* 8 - bytes CIST Regional Root Identifier
* 2 - bytes CIST Port Identifier
* 2 - bytes Message Age
* 2 - bytes Max age
* 2 - bytes Hello Time
* 2 - bytes Forward delay
* 1 - byte Version 1 length. Must be 0
* 2 - bytes Version 3 length
* 1 - byte Config Identifier
* 32 - bytes Config Name
* 2 - bytes Revision level
* 16 - bytes Config Digest [MD5]
* 4 - bytes CIST Internal Root Path Cost
* 8 - bytes CIST Bridge Identifier
* 1 - byte CIST Remaining Hops
* 16 - bytes MSTI information [Max 64 MSTI, each 16 bytes]
*
*
* SPB BPDU
* Ref. IEEE 802.1aq. Section 14
*
* 2 - bytes Version 4 length
* 1 - byte Aux Config Identifier
* 32 - bytes Aux Config Name
* 2 - bytes Aux Revision level
* 16 - bytes Aux Config Digest [MD5]
* 1 - byte (1 - 2) Agreement Number
* (3 - 4) Discarded Agreement Number
* (5) Agreement Valid Flag
* (6) Restricted Role Flag
* (7 - 8) Unused sent zero
* 1 - byte Unused
* 1 - byte (1 - 4) Agreement Digest Format Identifier
* (5 - 8) Agreement Digest Format Capabilities
* 1 - byte (1 - 4) Agreement Digest Convention Identifier
* (5 - 8) Agreement Digest Convention Capabilities
* 2 - bytes Agreement Digest Edge Count
* 8 - byte Reserved Set
* 20 - bytes Computed Topology Digest
*
*
* MSTI Payload
*
* 1 - byte MSTI flag
* 8 - bytes MSTI Regional Root Identifier
* 4 - bytes MSTI Regional Path Cost
* 1 - byte MSTI Bridge Priority
* 1 - byte MSTI Port Priority
* 1 - byte MSTI Remaining Hops
*
*/

#define MST_BPDU_MSTI_LENGTH 16
#define MST_BPDU_CONFIG_INFO_LENGTH 64

/* Offsets of fields from the beginning for the packet */
#define MST_BPDU_VER3_LEN_OFFSET 36
#define MST_BPDU_CONFIG_NAME_OFFSET 39
#define MST_BPDU_CONFIG_DIGEST_OFFSET 73
#define MST_BPDU_CIST_INT_PATH_COST_OFFSET 89
#define MST_BPDU_CIST_BRIDGE_ID_OFFSET 93
#define MST_BPDU_CIST_REMAIN_HOPS_OFFSET 101
#define MST_BPDU_MSTI_OFFSET 102
/* Offsets within an MSTI */
#define MST_BPDU_MSTI_ROOT_PRIO_OFFSET 1
#define MST_BPDU_MSTI_ROOT_PATH_COST_OFFSET 9
#define MST_BPDU_MSTI_BRIDGE_PRIO_OFFSET 13
#define MST_BPDU_MSTI_PORT_PRIO_OFFSET 14
#define MST_BPDU_MSTI_REMAIN_HOPS_OFFSET 15

#define SPB_BPDU_MIN_LEN 87
#define SPB_BPDU_CONFIG_NAME_OFFSET 3
#define SPB_BPDU_CONFIG_REV_OFFSET SPB_BPDU_CONFIG_NAME_OFFSET + 32
#define SPB_BPDU_CONFIG_DIGEST_OFFSET SPB_BPDU_CONFIG_REV_OFFSET + 2
#define SPB_BPDU_AGREEMENT_OFFSET SPB_BPDU_CONFIG_DIGEST_OFFSET + 16
#define SPB_BPDU_AGREEMENT_UNUSED_OFFSET SPB_BPDU_AGREEMENT_OFFSET + 1
#define SPB_BPDU_AGREEMENT_FORMAT_OFFSET SPB_BPDU_AGREEMENT_UNUSED_OFFSET + 1
#define SPB_BPDU_AGREEMENT_CON_OFFSET SPB_BPDU_AGREEMENT_FORMAT_OFFSET + 1
#define SPB_BPDU_AGREEMENT_EDGE_OFFSET SPB_BPDU_AGREEMENT_CON_OFFSET + 1
#define SPB_BPDU_AGREEMENT_RES1_OFFSET SPB_BPDU_AGREEMENT_EDGE_OFFSET + 2
#define SPB_BPDU_AGREEMENT_RES2_OFFSET SPB_BPDU_AGREEMENT_RES1_OFFSET + 4
#define SPB_BPDU_AGREEMENT_DIGEST_OFFSET SPB_BPDU_AGREEMENT_RES2_OFFSET + 4

static void
stp_print_mstp_bpdu(netdissect_options *ndo, const struct stp_bpdu_ *stp_bpdu,
u_int length)
{
const u_char *ptr;
uint8_t bpdu_flags;
uint16_t v3len;
uint16_t len;
uint16_t msti;
u_int offset;

ptr = (const u_char *)stp_bpdu;
bpdu_flags = GET_U_1(stp_bpdu->flags);
ND_PRINT(", CIST Flags [%s], length %u",
bittok2str(stp_bpdu_flag_values, "none", bpdu_flags), length);

/*
* in non-verbose mode just print the flags.
*/
if (!ndo->ndo_vflag) {
return;
}

ND_PRINT("\n\tport-role %s, ",
tok2str(rstp_obj_port_role_values, "Unknown",
RSTP_EXTRACT_PORT_ROLE(bpdu_flags)));

ND_PRINT("CIST root-id %s, CIST ext-pathcost %u",
stp_print_bridge_id(ndo, stp_bpdu->root_id),
GET_BE_U_4(stp_bpdu->root_path_cost));

ND_PRINT("\n\tCIST regional-root-id %s, ",
stp_print_bridge_id(ndo, stp_bpdu->bridge_id));

ND_PRINT("CIST port-id %04x,", GET_BE_U_2(stp_bpdu->port_id));

ND_PRINT("\n\tmessage-age %.2fs, max-age %.2fs"
", hello-time %.2fs, forwarding-delay %.2fs",
(float) GET_BE_U_2(stp_bpdu->message_age) / STP_TIME_BASE,
(float) GET_BE_U_2(stp_bpdu->max_age) / STP_TIME_BASE,
(float) GET_BE_U_2(stp_bpdu->hello_time) / STP_TIME_BASE,
(float) GET_BE_U_2(stp_bpdu->forward_delay) / STP_TIME_BASE);

ND_PRINT("\n\tv3len %u, ", GET_BE_U_2(ptr + MST_BPDU_VER3_LEN_OFFSET));
ND_PRINT("MCID Name ");
nd_printjnp(ndo, ptr + MST_BPDU_CONFIG_NAME_OFFSET, 32);
ND_PRINT(", rev %u,"
"\n\t\tdigest %08x%08x%08x%08x, ",
GET_BE_U_2(ptr + MST_BPDU_CONFIG_NAME_OFFSET + 32),
GET_BE_U_4(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET),
GET_BE_U_4(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 4),
GET_BE_U_4(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 8),
GET_BE_U_4(ptr + MST_BPDU_CONFIG_DIGEST_OFFSET + 12));

ND_PRINT("CIST int-root-pathcost %u,",
GET_BE_U_4(ptr + MST_BPDU_CIST_INT_PATH_COST_OFFSET));

ND_PRINT("\n\tCIST bridge-id %s, ",
stp_print_bridge_id(ndo, ptr + MST_BPDU_CIST_BRIDGE_ID_OFFSET));

ND_PRINT("CIST remaining-hops %u",
GET_U_1(ptr + MST_BPDU_CIST_REMAIN_HOPS_OFFSET));

/* Dump all MSTI's */
v3len = GET_BE_U_2(ptr + MST_BPDU_VER3_LEN_OFFSET);
if (v3len > MST_BPDU_CONFIG_INFO_LENGTH) {
len = v3len - MST_BPDU_CONFIG_INFO_LENGTH;
offset = MST_BPDU_MSTI_OFFSET;
while (len >= MST_BPDU_MSTI_LENGTH) {
msti = GET_BE_U_2(ptr + offset + MST_BPDU_MSTI_ROOT_PRIO_OFFSET);
msti = msti & 0x0FFF;

ND_PRINT("\n\tMSTI %u, Flags [%s], port-role %s",
msti,
bittok2str(stp_bpdu_flag_values, "none", GET_U_1(ptr + offset)),
tok2str(rstp_obj_port_role_values, "Unknown",
RSTP_EXTRACT_PORT_ROLE(GET_U_1(ptr + offset))));
ND_PRINT("\n\t\tMSTI regional-root-id %s, pathcost %u",
stp_print_bridge_id(ndo, ptr + offset +
MST_BPDU_MSTI_ROOT_PRIO_OFFSET),
GET_BE_U_4(ptr + offset + MST_BPDU_MSTI_ROOT_PATH_COST_OFFSET));
ND_PRINT("\n\t\tMSTI bridge-prio %u, port-prio %u, hops %u",
GET_U_1(ptr + offset + MST_BPDU_MSTI_BRIDGE_PRIO_OFFSET) >> 4,
GET_U_1(ptr + offset + MST_BPDU_MSTI_PORT_PRIO_OFFSET) >> 4,
GET_U_1(ptr + offset + MST_BPDU_MSTI_REMAIN_HOPS_OFFSET));

len -= MST_BPDU_MSTI_LENGTH;
offset += MST_BPDU_MSTI_LENGTH;
}
}
}

static void
stp_print_spb_bpdu(netdissect_options *ndo, const struct stp_bpdu_ *stp_bpdu,
u_int offset)
{
const u_char *ptr;

/*
* in non-verbose mode don't print anything.
*/
if (!ndo->ndo_vflag) {
return;
}

ptr = (const u_char *)stp_bpdu;

ND_PRINT("\n\tv4len %u, ", GET_BE_U_2(ptr + offset));
ND_PRINT("AUXMCID Name ");
nd_printjnp(ndo, ptr + offset + SPB_BPDU_CONFIG_NAME_OFFSET, 32);
ND_PRINT(", Rev %u,\n\t\tdigest %08x%08x%08x%08x",
GET_BE_U_2(ptr + offset + SPB_BPDU_CONFIG_REV_OFFSET),
GET_BE_U_4(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET),
GET_BE_U_4(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET + 4),
GET_BE_U_4(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET + 8),
GET_BE_U_4(ptr + offset + SPB_BPDU_CONFIG_DIGEST_OFFSET + 12));

ND_PRINT("\n\tAgreement num %u, Discarded Agreement num %u, Agreement valid-"
"flag %u,\n\tRestricted role-flag: %u, Format id %u cap %u, "
"Convention id %u cap %u,\n\tEdge count %u, "
"Agreement digest %08x%08x%08x%08x%08x",
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_OFFSET)>>6,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_OFFSET)>>4 & 0x3,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_OFFSET)>>3 & 0x1,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_OFFSET)>>2 & 0x1,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_FORMAT_OFFSET)>>4,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_FORMAT_OFFSET)&0x00ff,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_CON_OFFSET)>>4,
GET_U_1(ptr + offset + SPB_BPDU_AGREEMENT_CON_OFFSET)&0x00ff,
GET_BE_U_2(ptr + offset + SPB_BPDU_AGREEMENT_EDGE_OFFSET),
GET_BE_U_4(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET),
GET_BE_U_4(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET + 4),
GET_BE_U_4(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET + 8),
GET_BE_U_4(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET + 12),
GET_BE_U_4(ptr + offset + SPB_BPDU_AGREEMENT_DIGEST_OFFSET + 16));
}

/*
* Print 802.1d / 802.1w / 802.1q (mstp) / 802.1aq (spb) packets.
*/
void
stp_print(netdissect_options *ndo, const u_char *p, u_int length)
{
const struct stp_bpdu_ *stp_bpdu;
u_int protocol_version;
u_int bpdu_type;
u_int mstp_len;
u_int spb_len;

ndo->ndo_protocol = "stp";
stp_bpdu = (const struct stp_bpdu_*)p;

/* Minimum STP Frame size. */
if (length < 4)
goto invalid;

if (GET_BE_U_2(stp_bpdu->protocol_id)) {
ND_PRINT("unknown STP version, length %u", length);
return;
}

protocol_version = GET_U_1(stp_bpdu->protocol_version);
ND_PRINT("STP %s", tok2str(stp_proto_values, "Unknown STP protocol (0x%02x)",
protocol_version));

switch (protocol_version) {
case STP_PROTO_REGULAR:
case STP_PROTO_RAPID:
case STP_PROTO_MSTP:
case STP_PROTO_SPB:
break;
default:
return;
}

bpdu_type = GET_U_1(stp_bpdu->bpdu_type);
ND_PRINT(", %s", tok2str(stp_bpdu_type_values, "Unknown BPDU Type (0x%02x)",
bpdu_type));

switch (bpdu_type) {
case STP_BPDU_TYPE_CONFIG:
if (length < sizeof(struct stp_bpdu_) - 1) {
goto invalid;
}
stp_print_config_bpdu(ndo, stp_bpdu, length);
break;

case STP_BPDU_TYPE_RSTP:
if (protocol_version == STP_PROTO_RAPID) {
if (length < sizeof(struct stp_bpdu_)) {
goto invalid;
}
stp_print_config_bpdu(ndo, stp_bpdu, length);
} else if (protocol_version == STP_PROTO_MSTP ||
protocol_version == STP_PROTO_SPB) {
if (length < STP_BPDU_MSTP_MIN_LEN) {
goto invalid;
}

if (GET_U_1(stp_bpdu->v1_length) != 0) {
/* FIX ME: Emit a message here ? */
goto invalid;
}

/* Validate v3 length */
mstp_len = GET_BE_U_2(p + MST_BPDU_VER3_LEN_OFFSET);
mstp_len += 2; /* length encoding itself is 2 bytes */
if (length < (sizeof(struct stp_bpdu_) + mstp_len)) {
goto invalid;
}
stp_print_mstp_bpdu(ndo, stp_bpdu, length);

if (protocol_version == STP_PROTO_SPB) {
/* Validate v4 length */
spb_len = GET_BE_U_2(p + MST_BPDU_VER3_LEN_OFFSET + mstp_len);
spb_len += 2;
if (length < (sizeof(struct stp_bpdu_) + mstp_len + spb_len) ||
spb_len < SPB_BPDU_MIN_LEN) {
goto invalid;
}
stp_print_spb_bpdu(ndo, stp_bpdu, (sizeof(struct stp_bpdu_) + mstp_len));
}
}
break;

case STP_BPDU_TYPE_TOPO_CHANGE:
/* always empty message - just break out */
break;

default:
break;
}
return;

invalid:
nd_print_invalid(ndo);
}