nexmon – Rev 1
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/*
* 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
*/
#define NETDISSECT_REWORKED
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tcpdump-stdinc.h>
#include <stdio.h>
#include <string.h>
#include "interface.h"
#include "addrtoname.h"
#include "extract.h" /* must come after interface.h */
#include "ip.h"
#ifdef INET6
#include "ip6.h"
#endif
#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 {
uint16_t dccph_sport,
dccph_dport;
uint8_t dccph_doff;
uint8_t dccph_ccval_cscov;
uint16_t dccph_checksum;
uint8_t dccph_xtr;
uint8_t dccph_seq[3];
} UNALIGNED;
/**
* 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 {
uint16_t dccph_sport,
dccph_dport;
uint8_t dccph_doff;
uint8_t dccph_ccval_cscov;
uint16_t dccph_checksum;
uint8_t dccph_xtr;
uint8_t reserved;
uint8_t dccph_seq[6];
} UNALIGNED;
#define DCCPH_CCVAL(dh) (((dh)->dccph_ccval_cscov >> 4) & 0xF)
#define DCCPH_CSCOV(dh) (((dh)->dccph_ccval_cscov) & 0xF)
#define DCCPH_X(dh) ((dh)->dccph_xtr & 1)
#define DCCPH_TYPE(dh) (((dh)->dccph_xtr >> 1) & 0xF)
/**
* struct dccp_hdr_request - Conection initiation request header
*
* @dccph_req_service - Service to which the client app wants to connect
*/
struct dccp_hdr_request {
uint32_t dccph_req_service;
} UNALIGNED;
/**
* struct dccp_hdr_response - Conection 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 {
uint8_t dccph_resp_ack[8]; /* always 8 bytes */
uint32_t dccph_resp_service;
} UNALIGNED;
/**
* 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 {
uint8_t dccph_reset_ack[8]; /* always 8 bytes */
uint8_t dccph_reset_code,
dccph_reset_data[3];
} UNALIGNED;
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 tstr[] = "[|dccp]";
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 inline u_int dccp_csum_coverage(const struct dccp_hdr* dh, u_int len)
{
u_int cov;
if (DCCPH_CSCOV(dh) == 0)
return len;
cov = (dh->dccph_doff + DCCPH_CSCOV(dh) - 1) * sizeof(uint32_t);
return (cov > len)? len : cov;
}
static int 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 *)(void *)dh, len,
dccp_csum_coverage(dh, len), IPPROTO_DCCP);
}
#ifdef INET6
static int dccp6_cksum(const struct ip6_hdr *ip6, const struct dccp_hdr *dh, u_int len)
{
return nextproto6_cksum(ip6, (const uint8_t *)(void *)dh, len,
dccp_csum_coverage(dh, len), IPPROTO_DCCP);
}
#endif
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(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 = EXTRACT_48BITS(dhx->dccph_seq);
} else {
seqno = EXTRACT_24BITS(dh->dccph_seq);
}
return seqno;
}
static inline unsigned int dccp_basic_hdr_len(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(dh);
uint64_t ackno;
if (DCCPH_X(dh) != 0) {
ND_TCHECK2(*ackp, 8);
ackno = EXTRACT_48BITS(ackp + 2);
} else {
ND_TCHECK2(*ackp, 4);
ackno = EXTRACT_24BITS(ackp + 1);
}
ND_PRINT((ndo, "(ack=%" PRIu64 ") ", ackno));
trunc:
return;
}
static 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 - lenght 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;
#ifdef INET6
const struct ip6_hdr *ip6;
#endif
const u_char *cp;
u_short sport, dport;
u_int hlen;
u_int fixed_hdrlen;
uint8_t dccph_type;
dh = (const struct dccp_hdr *)bp;
ip = (struct ip *)data2;
#ifdef INET6
if (IP_V(ip) == 6)
ip6 = (const struct ip6_hdr *)data2;
else
ip6 = NULL;
#endif /*INET6*/
/* make sure we have enough data to look at the X bit */
cp = (const u_char *)(dh + 1);
if (cp > ndo->ndo_snapend) {
ND_PRINT((ndo, "[Invalid packet|dccp]"));
return;
}
if (len < sizeof(struct dccp_hdr)) {
ND_PRINT((ndo, "truncated-dccp - %u bytes missing!",
len - (u_int)sizeof(struct dccp_hdr)));
return;
}
/* get the length of the generic header */
fixed_hdrlen = dccp_basic_hdr_len(dh);
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-dccp - %u bytes missing!",
len - fixed_hdrlen));
return;
}
ND_TCHECK2(*dh, fixed_hdrlen);
sport = EXTRACT_16BITS(&dh->dccph_sport);
dport = EXTRACT_16BITS(&dh->dccph_dport);
hlen = dh->dccph_doff * 4;
#ifdef INET6
if (ip6) {
ND_PRINT((ndo, "%s.%d > %s.%d: ",
ip6addr_string(ndo, &ip6->ip6_src), sport,
ip6addr_string(ndo, &ip6->ip6_dst), dport));
} else
#endif /*INET6*/
{
ND_PRINT((ndo, "%s.%d > %s.%d: ",
ipaddr_string(ndo, &ip->ip_src), sport,
ipaddr_string(ndo, &ip->ip_dst), dport));
}
ND_PRINT((ndo, "DCCP"));
if (ndo->ndo_qflag) {
ND_PRINT((ndo, " %d", len - hlen));
if (hlen > len) {
ND_PRINT((ndo, " [bad hdr length %u - too long, > %u]",
hlen, len));
}
return;
}
/* other variables in generic header */
if (ndo->ndo_vflag) {
ND_PRINT((ndo, " (CCVal %d, CsCov %d, ", DCCPH_CCVAL(dh), DCCPH_CSCOV(dh)));
}
/* checksum calculation */
if (ndo->ndo_vflag && ND_TTEST2(bp[0], len)) {
uint16_t sum = 0, dccp_sum;
dccp_sum = EXTRACT_16BITS(&dh->dccph_checksum);
ND_PRINT((ndo, "cksum 0x%04x ", dccp_sum));
if (IP_V(ip) == 4)
sum = dccp_cksum(ndo, ip, dh, len);
#ifdef INET6
else if (IP_V(ip) == 6)
sum = dccp6_cksum(ip6, dh, len);
#endif
if (sum != 0)
ND_PRINT((ndo, "(incorrect -> 0x%04x)",in_cksum_shouldbe(dccp_sum, sum)));
else
ND_PRINT((ndo, "(correct)"));
}
if (ndo->ndo_vflag)
ND_PRINT((ndo, ")"));
ND_PRINT((ndo, " "));
dccph_type = DCCPH_TYPE(dh);
switch (dccph_type) {
case DCCP_PKT_REQUEST: {
struct dccp_hdr_request *dhr =
(struct dccp_hdr_request *)(bp + fixed_hdrlen);
fixed_hdrlen += 4;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_TCHECK(*dhr);
ND_PRINT((ndo, "%s (service=%d) ",
tok2str(dccp_pkt_type_str, "", dccph_type),
EXTRACT_32BITS(&dhr->dccph_req_service)));
break;
}
case DCCP_PKT_RESPONSE: {
struct dccp_hdr_response *dhr =
(struct dccp_hdr_response *)(bp + fixed_hdrlen);
fixed_hdrlen += 12;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_TCHECK(*dhr);
ND_PRINT((ndo, "%s (service=%d) ",
tok2str(dccp_pkt_type_str, "", dccph_type),
EXTRACT_32BITS(&dhr->dccph_resp_service)));
break;
}
case DCCP_PKT_DATA:
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
case DCCP_PKT_ACK: {
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
}
case DCCP_PKT_DATAACK: {
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
}
case DCCP_PKT_CLOSEREQ:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
case DCCP_PKT_CLOSE:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
case DCCP_PKT_RESET: {
struct dccp_hdr_reset *dhr =
(struct dccp_hdr_reset *)(bp + fixed_hdrlen);
fixed_hdrlen += 12;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_TCHECK(*dhr);
ND_PRINT((ndo, "%s (code=%s) ",
tok2str(dccp_pkt_type_str, "", dccph_type),
dccp_reset_code(dhr->dccph_reset_code)));
break;
}
case DCCP_PKT_SYNC:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
case DCCP_PKT_SYNCACK:
fixed_hdrlen += 8;
if (len < fixed_hdrlen) {
ND_PRINT((ndo, "truncated-%s - %u bytes missing!",
tok2str(dccp_pkt_type_str, "", dccph_type),
len - fixed_hdrlen));
return;
}
ND_PRINT((ndo, "%s ", tok2str(dccp_pkt_type_str, "", dccph_type)));
break;
default:
ND_PRINT((ndo, "%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((ndo, "seq %" PRIu64, dccp_seqno(bp)));
/* process options */
if (hlen > fixed_hdrlen){
const u_char *cp;
u_int optlen;
cp = bp + fixed_hdrlen;
ND_PRINT((ndo, " <"));
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((ndo, ", "));
}
ND_PRINT((ndo, ">"));
}
return;
trunc:
ND_PRINT((ndo, "%s", tstr));
return;
}
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 int dccp_print_option(netdissect_options *ndo, const u_char *option, u_int hlen)
{
uint8_t optlen, i;
ND_TCHECK(*option);
if (*option >= 32) {
ND_TCHECK(*(option+1));
optlen = *(option +1);
if (optlen < 2) {
if (*option >= 128)
ND_PRINT((ndo, "CCID option %u optlen too short", *option));
else
ND_PRINT((ndo, "%s optlen too short",
tok2str(dccp_option_values, "Option %u", *option)));
return 0;
}
} else
optlen = 1;
if (hlen < optlen) {
if (*option >= 128)
ND_PRINT((ndo, "CCID option %u optlen goes past header length",
*option));
else
ND_PRINT((ndo, "%s optlen goes past header length",
tok2str(dccp_option_values, "Option %u", *option)));
return 0;
}
ND_TCHECK2(*option, optlen);
if (*option >= 128) {
ND_PRINT((ndo, "CCID option %d", *option));
switch (optlen) {
case 4:
ND_PRINT((ndo, " %u", EXTRACT_16BITS(option + 2)));
break;
case 6:
ND_PRINT((ndo, " %u", EXTRACT_32BITS(option + 2)));
break;
default:
break;
}
} else {
ND_PRINT((ndo, "%s", tok2str(dccp_option_values, "Option %u", *option)));
switch (*option) {
case 32:
case 33:
case 34:
case 35:
if (optlen < 3) {
ND_PRINT((ndo, " optlen too short"));
return optlen;
}
if (*(option + 2) < 10){
ND_PRINT((ndo, " %s", dccp_feature_nums[*(option + 2)]));
for (i = 0; i < optlen - 3; i++)
ND_PRINT((ndo, " %d", *(option + 3 + i)));
}
break;
case 36:
if (optlen > 2) {
ND_PRINT((ndo, " 0x"));
for (i = 0; i < optlen - 2; i++)
ND_PRINT((ndo, "%02x", *(option + 2 + i)));
}
break;
case 37:
for (i = 0; i < optlen - 2; i++)
ND_PRINT((ndo, " %d", *(option + 2 + i)));
break;
case 38:
if (optlen > 2) {
ND_PRINT((ndo, " 0x"));
for (i = 0; i < optlen - 2; i++)
ND_PRINT((ndo, "%02x", *(option + 2 + i)));
}
break;
case 39:
if (optlen > 2) {
ND_PRINT((ndo, " 0x"));
for (i = 0; i < optlen - 2; i++)
ND_PRINT((ndo, "%02x", *(option + 2 + i)));
}
break;
case 40:
if (optlen > 2) {
ND_PRINT((ndo, " 0x"));
for (i = 0; i < optlen - 2; i++)
ND_PRINT((ndo, "%02x", *(option + 2 + i)));
}
break;
case 41:
if (optlen == 4)
ND_PRINT((ndo, " %u", EXTRACT_32BITS(option + 2)));
else
ND_PRINT((ndo, " optlen != 4"));
break;
case 42:
if (optlen == 4)
ND_PRINT((ndo, " %u", EXTRACT_32BITS(option + 2)));
else
ND_PRINT((ndo, " optlen != 4"));
break;
case 43:
if (optlen == 6)
ND_PRINT((ndo, " %u", EXTRACT_32BITS(option + 2)));
else if (optlen == 4)
ND_PRINT((ndo, " %u", EXTRACT_16BITS(option + 2)));
else
ND_PRINT((ndo, " optlen != 4 or 6"));
break;
case 44:
if (optlen > 2) {
ND_PRINT((ndo, " "));
for (i = 0; i < optlen - 2; i++)
ND_PRINT((ndo, "%02x", *(option + 2 + i)));
}
break;
}
}
return optlen;
trunc:
ND_PRINT((ndo, "%s", tstr));
return 0;
}