/*
 * 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
 */

#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"

/**
 * struct dccp_hdr - generic part of DCCP packet header
 *
 * @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 - sequence number high or low order 24 bits, depends on dccph_x
 */
struct dccp_hdr {
	u_int16_t	dccph_sport,
			dccph_dport;
	u_int8_t	dccph_doff;
	u_int8_t	dccph_ccval_cscov;
	u_int16_t	dccph_checksum;
	union {
	u_int8_t	dccph_xtr;
	u_int32_t	dccph_seq;
	}		dccph_xtrs;
};

#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_xtrs.dccph_xtr & 1)
#define DCCPH_TYPE(dh)	(((dh)->dccph_xtrs.dccph_xtr >> 1) & 0xF)
#define DCCPH_SEQ(dh)   (((dh)->dccph_xtrs.dccph_seq) >> 8)

/**
 * struct dccp_hdr_ext - the low bits of a 48 bit seq packet
 *
 * @dccph_seq_low - low 24 bits of a 48 bit seq packet
 */
struct dccp_hdr_ext {
	u_int32_t	dccph_seq_low;
};

/**
 * struct dccp_hdr_request - Conection initiation request header
 *
 * @dccph_req_service - Service to which the client app wants to connect
 */
struct dccp_hdr_request {
	u_int32_t	dccph_req_service;
};

/**
 * struct dccp_hdr_ack_bits - acknowledgment bits common to most packets
 *
 * @dccph_resp_ack_nr_high - 48 bit ack number high order bits, contains GSR
 * @dccph_resp_ack_nr_low - 48 bit ack number low order bits, contains GSR
 */
struct dccp_hdr_ack_bits {
	u_int32_t	dccph_ra;
	u_int32_t	dccph_ack_nr_low;
};

#define DCCPH_ACK(dh_ack)   ((dh_ack)->dccph_ra >> 8)

/**
 * struct dccp_hdr_response - Conection initiation response header
 *
 * @dccph_resp_ack_nr_high - 48 bit ack number high order bits, contains GSR
 * @dccph_resp_ack_nr_low - 48 bit ack number low order bits, contains GSR
 * @dccph_resp_service - Echoes the Service Code on a received DCCP-Request
 */
struct dccp_hdr_response {
	struct dccp_hdr_ack_bits	dccph_resp_ack;
	u_int32_t			dccph_resp_service;
};

/**
 * struct dccp_hdr_reset - Unconditionally shut down a connection
 *
 * @dccph_reset_service - Echoes the Service Code on a received DCCP-Request
 */
struct dccp_hdr_reset {
	struct dccp_hdr_ack_bits	dccph_reset_ack;
	u_int8_t			dccph_reset_code,
					dccph_reset_data[3];
};

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,
	DCCP_PKT_INVALID
};

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(u_int32_t);
	return (cov > len)? len : cov;
}

static int dccp_cksum(const struct ip *ip,
	const struct dccp_hdr *dh, u_int len)
{
	return nextproto4_cksum(ip, (const u_int8_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 u_int8_t *)(void *)dh,
	    dccp_csum_coverage(dh, len), IPPROTO_DCCP);
}
#endif

static const char *dccp_reset_code(u_int8_t code)
{
	if (code >= __DCCP_RESET_CODE_LAST)
		return "invalid";
	return dccp_reset_codes[code];
}

static u_int64_t dccp_seqno(const struct dccp_hdr *dh)
{
	u_int32_t seq_high = DCCPH_SEQ(dh);
	u_int64_t seqno = EXTRACT_24BITS(&seq_high) & 0xFFFFFF;

	if (DCCPH_X(dh) != 0) {
		const struct dccp_hdr_ext *dhx = (void *)(dh + 1);
		u_int32_t seq_low = dhx->dccph_seq_low;
		seqno &= 0x00FFFF;  /* clear reserved field */
		seqno = (seqno << 32) + EXTRACT_32BITS(&seq_low);
	}

	return seqno;
}

static inline unsigned int dccp_basic_hdr_len(const struct dccp_hdr *dh)
{
	return sizeof(*dh) + (DCCPH_X(dh) ? sizeof(struct dccp_hdr_ext) : 0);
}

static void dccp_print_ack_no(const u_char *bp)
{
	const struct dccp_hdr *dh = (const struct dccp_hdr *)bp;
	const struct dccp_hdr_ack_bits *dh_ack =
		(struct dccp_hdr_ack_bits *)(bp + dccp_basic_hdr_len(dh));
	u_int32_t ack_high;
	u_int64_t ackno;

	TCHECK2(*dh_ack,4);
	ack_high = DCCPH_ACK(dh_ack);
	ackno = EXTRACT_24BITS(&ack_high) & 0xFFFFFF;

	if (DCCPH_X(dh) != 0) {
		u_int32_t ack_low;

		TCHECK2(*dh_ack,8);
		ack_low = dh_ack->dccph_ack_nr_low;

		ackno &= 0x00FFFF;  /* clear reserved field */
		ackno = (ackno << 32) + EXTRACT_32BITS(&ack_low);
	}

	(void)printf("(ack=%" PRIu64 ") ", ackno);
trunc:
	return;
}

static inline unsigned int dccp_packet_hdr_len(const u_int8_t type)
{
	if (type == DCCP_PKT_DATA)
		return 0;
	if (type == DCCP_PKT_DATAACK	||
	    type == DCCP_PKT_ACK	||
	    type == DCCP_PKT_SYNC	||
	    type == DCCP_PKT_SYNCACK	||
	    type == DCCP_PKT_CLOSE	||
	    type == DCCP_PKT_CLOSEREQ)
		return sizeof(struct dccp_hdr_ack_bits);
	if (type == DCCP_PKT_REQUEST)
		return sizeof(struct dccp_hdr_request);
	if (type == DCCP_PKT_RESPONSE)
		return sizeof(struct dccp_hdr_response);
	return sizeof(struct dccp_hdr_reset);
}

static int dccp_print_option(const u_char *option);

/**
 * dccp_print - show dccp packet
 * @bp - beginning of dccp packet
 * @data2 - beginning of enclosing
 * @len - lenght of ip packet
 */
void dccp_print(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 extlen = 0;

	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*/
	cp = (const u_char *)(dh + 1);
	if (cp > snapend) {
		printf("[Invalid packet|dccp]");
		return;
	}

	if (len < sizeof(struct dccp_hdr)) {
		printf("truncated-dccp - %ld bytes missing!",
			     (long)len - sizeof(struct dccp_hdr));
		return;
	}

	sport = EXTRACT_16BITS(&dh->dccph_sport);
	dport = EXTRACT_16BITS(&dh->dccph_dport);
	hlen = dh->dccph_doff * 4;

#ifdef INET6
	if (ip6) {
		(void)printf("%s.%d > %s.%d: ",
			     ip6addr_string(&ip6->ip6_src), sport,
			     ip6addr_string(&ip6->ip6_dst), dport);
	} else
#endif /*INET6*/
	{
		(void)printf("%s.%d > %s.%d: ",
			     ipaddr_string(&ip->ip_src), sport,
			     ipaddr_string(&ip->ip_dst), dport);
	}
	fflush(stdout);

	if (qflag) {
		(void)printf(" %d", len - hlen);
		if (hlen > len) {
			(void)printf("dccp [bad hdr length %u - too long, > %u]",
			    hlen, len);
		}
		return;
	}

	/* other variables in generic header */
	if (vflag) {
		(void)printf("CCVal %d, CsCov %d, ", DCCPH_CCVAL(dh), DCCPH_CSCOV(dh));
	}

	/* checksum calculation */
	if (vflag && TTEST2(bp[0], len)) {
		u_int16_t sum = 0, dccp_sum;

		dccp_sum = EXTRACT_16BITS(&dh->dccph_checksum);
		(void)printf("cksum 0x%04x ", dccp_sum);
		if (IP_V(ip) == 4)
			sum = dccp_cksum(ip, dh, len);
#ifdef INET6
		else if (IP_V(ip) == 6)
			sum = dccp6_cksum(ip6, dh, len);
#endif
		if (sum != 0)
			(void)printf("(incorrect -> 0x%04x), ",in_cksum_shouldbe(dccp_sum, sum));
		else
			(void)printf("(correct), ");
	}

	switch (DCCPH_TYPE(dh)) {
	case DCCP_PKT_REQUEST: {
		struct dccp_hdr_request *dhr =
			(struct dccp_hdr_request *)(bp + dccp_basic_hdr_len(dh));
		TCHECK(*dhr);
		(void)printf("request (service=%d) ",
			     EXTRACT_32BITS(&dhr->dccph_req_service));
		extlen += 4;
		break;
	}
	case DCCP_PKT_RESPONSE: {
		struct dccp_hdr_response *dhr =
			(struct dccp_hdr_response *)(bp + dccp_basic_hdr_len(dh));
		TCHECK(*dhr);
		(void)printf("response (service=%d) ",
			     EXTRACT_32BITS(&dhr->dccph_resp_service));
		extlen += 12;
		break;
	}
	case DCCP_PKT_DATA:
		(void)printf("data ");
		break;
	case DCCP_PKT_ACK: {
		(void)printf("ack ");
		extlen += 8;
		break;
	}
	case DCCP_PKT_DATAACK: {
		(void)printf("dataack ");
		extlen += 8;
		break;
	}
	case DCCP_PKT_CLOSEREQ:
		(void)printf("closereq ");
		extlen += 8;
		break;
	case DCCP_PKT_CLOSE:
		(void)printf("close ");
		extlen += 8;
		break;
	case DCCP_PKT_RESET: {
		struct dccp_hdr_reset *dhr =
			(struct dccp_hdr_reset *)(bp + dccp_basic_hdr_len(dh));
		TCHECK(*dhr);
		(void)printf("reset (code=%s) ",
			     dccp_reset_code(dhr->dccph_reset_code));
		extlen += 12;
		break;
	}
	case DCCP_PKT_SYNC:
		(void)printf("sync ");
		extlen += 8;
		break;
	case DCCP_PKT_SYNCACK:
		(void)printf("syncack ");
		extlen += 8;
		break;
	default:
		(void)printf("invalid ");
		break;
	}

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

	if (vflag < 2)
		return;

	(void)printf("seq %" PRIu64, dccp_seqno(dh));

	/* process options */
	if (hlen > dccp_basic_hdr_len(dh) + extlen){
		const u_char *cp;
		u_int optlen;
		cp = bp + dccp_basic_hdr_len(dh) + extlen;
		printf(" <");

		hlen -= dccp_basic_hdr_len(dh) + extlen;
		while(1){
			TCHECK(*cp);
			optlen = dccp_print_option(cp);
			if (!optlen) goto trunc2;
			if (hlen <= optlen) break;
			hlen -= optlen;
			cp += optlen;
			printf(", ");
		}
		printf(">");
	}
	return;
trunc:
	printf("%s", tstr);
trunc2:
	return;
}

static int dccp_print_option(const u_char *option)
{
	u_int8_t optlen, i;

	TCHECK(*option);

	if (*option >= 32) {
		TCHECK(*(option+1));
		optlen = *(option +1);
		if (optlen < 2) {
			printf("Option %d optlen too short",*option);
			return 1;
		}
	} else optlen = 1;

	TCHECK2(*option,optlen);

	switch (*option){
	case 0:
		printf("nop");
		break;
	case 1:
		printf("mandatory");
		break;
	case 2:
		printf("slowreceiver");
		break;
	case 32:
		printf("change_l");
		if (*(option +2) < 10){
			printf(" %s", dccp_feature_nums[*(option +2)]);
			for (i = 0; i < optlen -3; i ++) printf(" %d", *(option +3 + i));
		}
		break;
	case 33:
		printf("confirm_l");
		if (*(option +2) < 10){
			printf(" %s", dccp_feature_nums[*(option +2)]);
			for (i = 0; i < optlen -3; i ++) printf(" %d", *(option +3 + i));
		}
		break;
	case 34:
	        printf("change_r");
		if (*(option +2) < 10){
			printf(" %s", dccp_feature_nums[*(option +2)]);
			for (i = 0; i < optlen -3; i ++) printf(" %d", *(option +3 + i));
		}
		break;
	case 35:
		printf("confirm_r");
		if (*(option +2) < 10){
			printf(" %s", dccp_feature_nums[*(option +2)]);
			for (i = 0; i < optlen -3; i ++) printf(" %d", *(option +3 + i));
		}
		break;
	case 36:
		printf("initcookie 0x");
		for (i = 0; i < optlen -2; i ++) printf("%02x", *(option +2 + i));
		break;
	case 37:
		printf("ndp_count");
		for (i = 0; i < optlen -2; i ++) printf(" %d", *(option +2 + i));
		break;
	case 38:
		printf("ack_vector0 0x");
		for (i = 0; i < optlen -2; i ++) printf("%02x", *(option +2 + i));
		break;
	case 39:
		printf("ack_vector1 0x");
		for (i = 0; i < optlen -2; i ++) printf("%02x", *(option +2 + i));
		break;
	case 40:
		printf("data_dropped 0x");
		for (i = 0; i < optlen -2; i ++) printf("%02x", *(option +2 + i));
		break;
	case 41:
		printf("timestamp %u", EXTRACT_32BITS(option + 2));
		break;
	case 42:
		printf("timestamp_echo %u", EXTRACT_32BITS(option + 2));
		break;
	case 43:
		printf("elapsed_time ");
		if (optlen == 6)
			printf("%u", EXTRACT_32BITS(option + 2));
		else
			printf("%u", EXTRACT_16BITS(option + 2));
		break;
	case 44:
		printf("data_checksum ");
		for (i = 0; i < optlen -2; i ++) printf("%02x", *(option +2 + i));
		break;
	default :
		if (*option >= 128) {
			printf("CCID option %d",*option);
			switch (optlen) {
				case 4:
					printf(" %u", EXTRACT_16BITS(option + 2));
					break;
				case 6:
					printf(" %u", EXTRACT_32BITS(option + 2));
					break;
				default:
					break;
			}
			break;
		}

		printf("unknown_opt %d", *option);
		break;
	}

	return optlen;
trunc:
	printf("%s", tstr);
	return 0;
}