* Copyright (C) Arnaldo Carvalho de Melo 2004

/*
* Copyright (C) Arnaldo Carvalho de Melo 2004
* Copyright (C) Ian McDonald 2005
* Copyright (C) Yoshifumi Nishida 2005
*
* This software may be distributed either under the terms of the
* BSD-style license that accompanies tcpdump or the GNU GPL version 2
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-dccp.c,v 1.10 2024/09/02 16:15:31 christos Exp $");
#endif

/* \summary: Datagram Congestion Control Protocol (DCCP) printer */

/* specification: RFC 4340 */

#include <config.h>

#include "netdissect-stdinc.h"

#include "netdissect.h"
#include "addrtoname.h"
#include "extract.h"
#include "ip.h"
#include "ip6.h"
#include "ipproto.h"

/* RFC4340: Datagram Congestion Control Protocol (DCCP) */

/**
* struct dccp_hdr - generic part of DCCP packet header, with a 24-bit
* sequence number
*
* @dccph_sport - Relevant port on the endpoint that sent this packet
* @dccph_dport - Relevant port on the other endpoint
* @dccph_doff - Data Offset from the start of the DCCP header, in 32-bit words
* @dccph_ccval - Used by the HC-Sender CCID
* @dccph_cscov - Parts of the packet that are covered by the Checksum field
* @dccph_checksum - Internet checksum, depends on dccph_cscov
* @dccph_x - 0 = 24 bit sequence number, 1 = 48
* @dccph_type - packet type, see DCCP_PKT_ prefixed macros
* @dccph_seq - 24-bit sequence number
*/
struct dccp_hdr {
nd_uint16_t dccph_sport,
dccph_dport;
nd_uint8_t dccph_doff;
nd_uint8_t dccph_ccval_cscov;
nd_uint16_t dccph_checksum;
nd_uint8_t dccph_xtr;
nd_uint24_t dccph_seq;
};

/**
* struct dccp_hdr_ext - generic part of DCCP packet header, with a 48-bit
* sequence number
*
* @dccph_sport - Relevant port on the endpoint that sent this packet
* @dccph_dport - Relevant port on the other endpoint
* @dccph_doff - Data Offset from the start of the DCCP header, in 32-bit words
* @dccph_ccval - Used by the HC-Sender CCID
* @dccph_cscov - Parts of the packet that are covered by the Checksum field
* @dccph_checksum - Internet checksum, depends on dccph_cscov
* @dccph_x - 0 = 24 bit sequence number, 1 = 48
* @dccph_type - packet type, see DCCP_PKT_ prefixed macros
* @dccph_seq - 48-bit sequence number
*/
struct dccp_hdr_ext {
nd_uint16_t dccph_sport,
dccph_dport;
nd_uint8_t dccph_doff;
nd_uint8_t dccph_ccval_cscov;
nd_uint16_t dccph_checksum;
nd_uint8_t dccph_xtr;
nd_uint8_t reserved;
nd_uint48_t dccph_seq;
};

#define DCCPH_CCVAL(dh) ((GET_U_1((dh)->dccph_ccval_cscov) >> 4) & 0xF)
#define DCCPH_CSCOV(dh) (GET_U_1((dh)->dccph_ccval_cscov) & 0xF)

#define DCCPH_X(dh) (GET_U_1((dh)->dccph_xtr) & 1)
#define DCCPH_TYPE(dh) ((GET_U_1((dh)->dccph_xtr) >> 1) & 0xF)

/**
* struct dccp_hdr_request - Connection initiation request header
*
* @dccph_req_service - Service to which the client app wants to connect
*/
struct dccp_hdr_request {
nd_uint32_t dccph_req_service;
};

/**
* struct dccp_hdr_response - Connection initiation response header
*
* @dccph_resp_ack - 48 bit ack number, contains GSR
* @dccph_resp_service - Echoes the Service Code on a received DCCP-Request
*/
struct dccp_hdr_response {
nd_uint64_t dccph_resp_ack; /* always 8 bytes, first 2 reserved */
nd_uint32_t dccph_resp_service;
};

/**
* struct dccp_hdr_reset - Unconditionally shut down a connection
*
* @dccph_resp_ack - 48 bit ack number
* @dccph_reset_service - Echoes the Service Code on a received DCCP-Request
*/
struct dccp_hdr_reset {
nd_uint64_t dccph_reset_ack; /* always 8 bytes, first 2 reserved */
nd_uint8_t dccph_reset_code;
nd_uint8_t dccph_reset_data1;
nd_uint8_t dccph_reset_data2;
nd_uint8_t dccph_reset_data3;
};

enum dccp_pkt_type {
DCCP_PKT_REQUEST = 0,
DCCP_PKT_RESPONSE,
DCCP_PKT_DATA,
DCCP_PKT_ACK,
DCCP_PKT_DATAACK,
DCCP_PKT_CLOSEREQ,
DCCP_PKT_CLOSE,
DCCP_PKT_RESET,
DCCP_PKT_SYNC,
DCCP_PKT_SYNCACK
};

static const struct tok dccp_pkt_type_str[] = {
{ DCCP_PKT_REQUEST, "DCCP-Request" },
{ DCCP_PKT_RESPONSE, "DCCP-Response" },
{ DCCP_PKT_DATA, "DCCP-Data" },
{ DCCP_PKT_ACK, "DCCP-Ack" },
{ DCCP_PKT_DATAACK, "DCCP-DataAck" },
{ DCCP_PKT_CLOSEREQ, "DCCP-CloseReq" },
{ DCCP_PKT_CLOSE, "DCCP-Close" },
{ DCCP_PKT_RESET, "DCCP-Reset" },
{ DCCP_PKT_SYNC, "DCCP-Sync" },
{ DCCP_PKT_SYNCACK, "DCCP-SyncAck" },
{ 0, NULL}
};

enum dccp_reset_codes {
DCCP_RESET_CODE_UNSPECIFIED = 0,
DCCP_RESET_CODE_CLOSED,
DCCP_RESET_CODE_ABORTED,
DCCP_RESET_CODE_NO_CONNECTION,
DCCP_RESET_CODE_PACKET_ERROR,
DCCP_RESET_CODE_OPTION_ERROR,
DCCP_RESET_CODE_MANDATORY_ERROR,
DCCP_RESET_CODE_CONNECTION_REFUSED,
DCCP_RESET_CODE_BAD_SERVICE_CODE,
DCCP_RESET_CODE_TOO_BUSY,
DCCP_RESET_CODE_BAD_INIT_COOKIE,
DCCP_RESET_CODE_AGGRESSION_PENALTY,
__DCCP_RESET_CODE_LAST
};

static const char *dccp_reset_codes[] = {
"unspecified",
"closed",
"aborted",
"no_connection",
"packet_error",
"option_error",
"mandatory_error",
"connection_refused",
"bad_service_code",
"too_busy",
"bad_init_cookie",
"aggression_penalty",
};

static const char *dccp_feature_nums[] = {
"reserved",
"ccid",
"allow_short_seqno",
"sequence_window",
"ecn_incapable",
"ack_ratio",
"send_ack_vector",
"send_ndp_count",
"minimum checksum coverage",
"check data checksum",
};

static u_int
dccp_csum_coverage(netdissect_options *ndo,
const struct dccp_hdr *dh, u_int len)
{
u_int cov;

if (DCCPH_CSCOV(dh) == 0)
return len;
cov = (GET_U_1(dh->dccph_doff) + DCCPH_CSCOV(dh) - 1) * sizeof(uint32_t);
return (cov > len)? len : cov;
}

static uint16_t dccp_cksum(netdissect_options *ndo, const struct ip *ip,
const struct dccp_hdr *dh, u_int len)
{
return nextproto4_cksum(ndo, ip, (const uint8_t *)(const void *)dh, len,
dccp_csum_coverage(ndo, dh, len), IPPROTO_DCCP);
}

static uint16_t dccp6_cksum(netdissect_options *ndo, const struct ip6_hdr *ip6,
const struct dccp_hdr *dh, u_int len)
{
return nextproto6_cksum(ndo, ip6, (const uint8_t *)(const void *)dh, len,
dccp_csum_coverage(ndo, dh, len), IPPROTO_DCCP);
}

static const char *dccp_reset_code(uint8_t code)
{
if (code >= __DCCP_RESET_CODE_LAST)
return "invalid";
return dccp_reset_codes[code];
}

static uint64_t
dccp_seqno(netdissect_options *ndo, const u_char *bp)
{
const struct dccp_hdr *dh = (const struct dccp_hdr *)bp;
uint64_t seqno;

if (DCCPH_X(dh) != 0) {
const struct dccp_hdr_ext *dhx = (const struct dccp_hdr_ext *)bp;
seqno = GET_BE_U_6(dhx->dccph_seq);
} else {
seqno = GET_BE_U_3(dh->dccph_seq);
}

return seqno;
}

static unsigned int
dccp_basic_hdr_len(netdissect_options *ndo, const struct dccp_hdr *dh)
{
return DCCPH_X(dh) ? sizeof(struct dccp_hdr_ext) : sizeof(struct dccp_hdr);
}

static void dccp_print_ack_no(netdissect_options *ndo, const u_char *bp)
{
const struct dccp_hdr *dh = (const struct dccp_hdr *)bp;
const u_char *ackp = bp + dccp_basic_hdr_len(ndo, dh);
uint64_t ackno;

if (DCCPH_X(dh) != 0) {
ackno = GET_BE_U_6(ackp + 2);
} else {
ackno = GET_BE_U_3(ackp + 1);
}

ND_PRINT("(ack=%" PRIu64 ") ", ackno);
}

static u_int dccp_print_option(netdissect_options *, const u_char *, u_int);

/**
* dccp_print - show dccp packet
* @bp - beginning of dccp packet
* @data2 - beginning of enclosing
* @len - length of ip packet
*/
void
dccp_print(netdissect_options *ndo, const u_char *bp, const u_char *data2,
u_int len)
{
const struct dccp_hdr *dh;
const struct ip *ip;
const struct ip6_hdr *ip6;
const u_char *cp;
u_short sport, dport;
u_int hlen;
u_int fixed_hdrlen;
uint8_t dccph_type;

ndo->ndo_protocol = "dccp";
dh = (const struct dccp_hdr *)bp;

ip = (const struct ip *)data2;
if (IP_V(ip) == 6)
ip6 = (const struct ip6_hdr *)data2;
else
ip6 = NULL;

/* make sure we have enough data to look at the X bit */
cp = (const u_char *)(dh + 1);
if (cp > ndo->ndo_snapend)
goto trunc;
if (len < sizeof(struct dccp_hdr)) {
ND_PRINT("truncated-dccp - %zu bytes missing!",
sizeof(struct dccp_hdr) - len);
return;
}

/* get the length of the generic header */
fixed_hdrlen = dccp_basic_hdr_len(ndo, dh);
if (len < fixed_hdrlen) {
ND_PRINT("truncated-dccp - %u bytes missing!",
fixed_hdrlen - len);
return;
}
ND_TCHECK_LEN(dh, fixed_hdrlen);

sport = GET_BE_U_2(dh->dccph_sport);
dport = GET_BE_U_2(dh->dccph_dport);
hlen = GET_U_1(dh->dccph_doff) * 4;

if (ip6) {
ND_PRINT("%s.%u > %s.%u: ",
GET_IP6ADDR_STRING(ip6->ip6_src), sport,
GET_IP6ADDR_STRING(ip6->ip6_dst), dport);
} else {
ND_PRINT("%s.%u > %s.%u: ",
GET_IPADDR_STRING(ip->ip_src), sport,
GET_IPADDR_STRING(ip->ip_dst), dport);
}

nd_print_protocol_caps(ndo);

if (ndo->ndo_qflag) {
ND_PRINT(" %u", len - hlen);
if (hlen > len) {
ND_PRINT(" [bad hdr length %u - too long, > %u]",
hlen, len);
}
return;
}

/* other variables in generic header */
if (ndo->ndo_vflag) {
ND_PRINT(" (CCVal %u, CsCov %u", DCCPH_CCVAL(dh), DCCPH_CSCOV(dh));
}

/* checksum calculation */
if (ndo->ndo_vflag && ND_TTEST_LEN(bp, len)) {
uint16_t sum = 0, dccp_sum;

dccp_sum = GET_BE_U_2(dh->dccph_checksum);
ND_PRINT(", cksum 0x%04x ", dccp_sum);
if (IP_V(ip) == 4)
sum = dccp_cksum(ndo, ip, dh, len);
else if (IP_V(ip) == 6)
sum = dccp6_cksum(ndo, ip6, dh, len);
if (sum != 0)
ND_PRINT("(incorrect -> 0x%04x)",in_cksum_shouldbe(dccp_sum, sum));
else
ND_PRINT("(correct)");
}

if (ndo->ndo_vflag)
ND_PRINT(")");
ND_PRINT(" ");

dccph_type = DCCPH_TYPE(dh);
switch (dccph_type) {
case DCCP_PKT_REQUEST: {
const struct dccp_hdr_request *dhr =
(const struct dccp_hdr_request *)(bp + fixed_hdrlen);
fixed_hdrlen += 4;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_TCHECK_SIZE(dhr);
ND_PRINT("%s (service=%u) ",
tok2str(dccp_pkt_type_str, "", dccph_type),
GET_BE_U_4(dhr->dccph_req_service));
break;
}
case DCCP_PKT_RESPONSE: {
const struct dccp_hdr_response *dhr =
(const struct dccp_hdr_response *)(bp + fixed_hdrlen);
fixed_hdrlen += 12;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_TCHECK_SIZE(dhr);
ND_PRINT("%s (service=%u) ",
tok2str(dccp_pkt_type_str, "", dccph_type),
GET_BE_U_4(dhr->dccph_resp_service));
break;
}
case DCCP_PKT_DATA:
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
case DCCP_PKT_ACK: {
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
}
case DCCP_PKT_DATAACK: {
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
}
case DCCP_PKT_CLOSEREQ:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
case DCCP_PKT_CLOSE:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
case DCCP_PKT_RESET: {
const struct dccp_hdr_reset *dhr =
(const struct dccp_hdr_reset *)(bp + fixed_hdrlen);
fixed_hdrlen += 12;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_TCHECK_SIZE(dhr);
ND_PRINT("%s (code=%s) ",
tok2str(dccp_pkt_type_str, "", dccph_type),
dccp_reset_code(GET_U_1(dhr->dccph_reset_code)));
break;
}
case DCCP_PKT_SYNC:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
case DCCP_PKT_SYNCACK:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT("truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
fixed_hdrlen - len);
return;
}
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "", dccph_type));
break;
default:
ND_PRINT("%s ", tok2str(dccp_pkt_type_str, "unknown-type-%u", dccph_type));
break;
}

if ((DCCPH_TYPE(dh) != DCCP_PKT_DATA) &&
(DCCPH_TYPE(dh) != DCCP_PKT_REQUEST))
dccp_print_ack_no(ndo, bp);

if (ndo->ndo_vflag < 2)
return;

ND_PRINT("seq %" PRIu64, dccp_seqno(ndo, bp));

/* process options */
if (hlen > fixed_hdrlen){
u_int optlen;
cp = bp + fixed_hdrlen;
ND_PRINT(" <");

hlen -= fixed_hdrlen;
while(1){
optlen = dccp_print_option(ndo, cp, hlen);
if (!optlen)
break;
if (hlen <= optlen)
break;
hlen -= optlen;
cp += optlen;
ND_PRINT(", ");
}
ND_PRINT(">");
}
return;
trunc:
nd_print_trunc(ndo);
}

static const struct tok dccp_option_values[] = {
{ 0, "nop" },
{ 1, "mandatory" },
{ 2, "slowreceiver" },
{ 32, "change_l" },
{ 33, "confirm_l" },
{ 34, "change_r" },
{ 35, "confirm_r" },
{ 36, "initcookie" },
{ 37, "ndp_count" },
{ 38, "ack_vector0" },
{ 39, "ack_vector1" },
{ 40, "data_dropped" },
{ 41, "timestamp" },
{ 42, "timestamp_echo" },
{ 43, "elapsed_time" },
{ 44, "data_checksum" },
{ 0, NULL }
};

static u_int
dccp_print_option(netdissect_options *ndo, const u_char *option, u_int hlen)
{
uint8_t optlen, i;

if (GET_U_1(option) >= 32) {
optlen = GET_U_1(option + 1);
if (optlen < 2) {
if (GET_U_1(option) >= 128)
ND_PRINT("CCID option %u optlen too short",
GET_U_1(option));
else
ND_PRINT("%s optlen too short",
tok2str(dccp_option_values, "Option %u", GET_U_1(option)));
return 0;
}
} else
optlen = 1;

if (hlen < optlen) {
if (GET_U_1(option) >= 128)
ND_PRINT("CCID option %u optlen goes past header length",
GET_U_1(option));
else
ND_PRINT("%s optlen goes past header length",
tok2str(dccp_option_values, "Option %u", GET_U_1(option)));
return 0;
}
ND_TCHECK_LEN(option, optlen);

if (GET_U_1(option) >= 128) {
ND_PRINT("CCID option %u", GET_U_1(option));
switch (optlen) {
case 4:
ND_PRINT(" %u", GET_BE_U_2(option + 2));
break;
case 6:
ND_PRINT(" %u", GET_BE_U_4(option + 2));
break;
default:
break;
}
} else {
ND_PRINT("%s",
tok2str(dccp_option_values, "Option %u", GET_U_1(option)));
switch (GET_U_1(option)) {
case 32:
case 33:
case 34:
case 35:
if (optlen < 3) {
ND_PRINT(" optlen too short");
return optlen;
}
if (GET_U_1(option + 2) < 10){
ND_PRINT(" %s",
dccp_feature_nums[GET_U_1(option + 2)]);
for (i = 0; i < optlen - 3; i++)
ND_PRINT(" %u",
GET_U_1(option + 3 + i));
}
break;
case 36:
if (optlen > 2) {
ND_PRINT(" 0x");
for (i = 0; i < optlen - 2; i++)
ND_PRINT("%02x",
GET_U_1(option + 2 + i));
}
break;
case 37:
for (i = 0; i < optlen - 2; i++)
ND_PRINT(" %u", GET_U_1(option + 2 + i));
break;
case 38:
if (optlen > 2) {
ND_PRINT(" 0x");
for (i = 0; i < optlen - 2; i++)
ND_PRINT("%02x",
GET_U_1(option + 2 + i));
}
break;
case 39:
if (optlen > 2) {
ND_PRINT(" 0x");
for (i = 0; i < optlen - 2; i++)
ND_PRINT("%02x",
GET_U_1(option + 2 + i));
}
break;
case 40:
if (optlen > 2) {
ND_PRINT(" 0x");
for (i = 0; i < optlen - 2; i++)
ND_PRINT("%02x",
GET_U_1(option + 2 + i));
}
break;
case 41:
/*
* 13.1. Timestamp Option
*
* +--------+--------+--------+--------+--------+--------+
* |00101001|00000110| Timestamp Value |
* +--------+--------+--------+--------+--------+--------+
* Type=41 Length=6
*/
if (optlen == 6)
ND_PRINT(" %u", GET_BE_U_4(option + 2));
else
ND_PRINT(" [optlen != 6]");
break;
case 42:
/*
* 13.3. Timestamp Echo Option
*
* +--------+--------+--------+--------+--------+--------+
* |00101010|00000110| Timestamp Echo |
* +--------+--------+--------+--------+--------+--------+
* Type=42 Len=6
*
* +--------+--------+------- ... -------+--------+--------+
* |00101010|00001000| Timestamp Echo | Elapsed Time |
* +--------+--------+------- ... -------+--------+--------+
* Type=42 Len=8 (4 bytes)
*
* +--------+--------+------- ... -------+------- ... -------+
* |00101010|00001010| Timestamp Echo | Elapsed Time |
* +--------+--------+------- ... -------+------- ... -------+
* Type=42 Len=10 (4 bytes) (4 bytes)
*/
switch (optlen) {
case 6:
ND_PRINT(" %u", GET_BE_U_4(option + 2));
break;
case 8:
ND_PRINT(" %u", GET_BE_U_4(option + 2));
ND_PRINT(" (elapsed time %u)",
GET_BE_U_2(option + 6));
break;
case 10:
ND_PRINT(" %u", GET_BE_U_4(option + 2));
ND_PRINT(" (elapsed time %u)",
GET_BE_U_4(option + 6));
break;
default:
ND_PRINT(" [optlen != 6 or 8 or 10]");
break;
}
break;
case 43:
if (optlen == 6)
ND_PRINT(" %u", GET_BE_U_4(option + 2));
else if (optlen == 4)
ND_PRINT(" %u", GET_BE_U_2(option + 2));
else
ND_PRINT(" [optlen != 4 or 6]");
break;
case 44:
if (optlen > 2) {
ND_PRINT(" ");
for (i = 0; i < optlen - 2; i++)
ND_PRINT("%02x",
GET_U_1(option + 2 + i));
}
break;
}
}

return optlen;
trunc:
nd_print_trunc(ndo);
return 0;
}