print-tcp.c

Windump3.6.2源代码

		 * both directions).
		 */
#ifdef INET6
		memset(&tha, 0, sizeof(tha));
		rev = 0;
		if (ip6) {
			if (sport > dport) {
				rev = 1;
			} else if (sport == dport) {
			    int i;

			    for (i = 0; i < 4; i++) {
				if (((u_int32_t *)(&ip6->ip6_src))[i] >
				    ((u_int32_t *)(&ip6->ip6_dst))[i]) {
					rev = 1;
					break;
				}
			    }
			}
			if (rev) {
				tha.src = ip6->ip6_dst;
				tha.dst = ip6->ip6_src;
				tha.port = dport << 16 | sport;
			} else {
				tha.dst = ip6->ip6_dst;
				tha.src = ip6->ip6_src;
				tha.port = sport << 16 | dport;
			}
		} else {
			if (sport > dport ||
			    (sport == dport &&
			     ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
				rev = 1;
			}
			if (rev) {
				*(struct in_addr *)&tha.src = ip->ip_dst;
				*(struct in_addr *)&tha.dst = ip->ip_src;
				tha.port = dport << 16 | sport;
			} else {
				*(struct in_addr *)&tha.dst = ip->ip_dst;
				*(struct in_addr *)&tha.src = ip->ip_src;
				tha.port = sport << 16 | dport;
			}
		}
#else
		if (sport < dport ||
		    (sport == dport &&
		     ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
			tha.src = ip->ip_src, tha.dst = ip->ip_dst;
			tha.port = sport << 16 | dport;
			rev = 0;
		} else {
			tha.src = ip->ip_dst, tha.dst = ip->ip_src;
			tha.port = dport << 16 | sport;
			rev = 1;
		}
#endif

		threv = rev;
		for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
		     th->nxt; th = th->nxt)
			if (!memcmp((char *)&tha, (char *)&th->addr,
				  sizeof(th->addr)))
				break;

		if (!th->nxt || (flags & TH_SYN)) {
			/* didn't find it or new conversation */
			if (th->nxt == NULL) {
				th->nxt = (struct tcp_seq_hash *)
					calloc(1, sizeof(*th));
				if (th->nxt == NULL)
					error("tcp_print: calloc");
			}
			th->addr = tha;
			if (rev)
				th->ack = seq, th->seq = ack - 1;
			else
				th->seq = seq, th->ack = ack - 1;

		} else {
			if (rev)
				seq -= th->ack, ack -= th->seq;
			else
				seq -= th->seq, ack -= th->ack;
		}

		thseq = th->seq;
		thack = th->ack;
	} else {
		/*fool gcc*/
		thseq = thack = threv = 0;
	}
	if (hlen > length) {
		(void)printf(" [bad hdr length]");
		return;
	}

	if (IP_V(ip) == 4 && vflag && !fragmented) {
		int sum;
		if (TTEST2(tp->th_sport, length)) {
			sum = tcp_cksum(ip, tp, length);
			if (sum != 0)
				(void)printf(" [bad tcp cksum %x!]", sum);
			else
				(void)printf(" [tcp sum ok]");
		}
	}
#ifdef INET6
	if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
		int sum;
		if (TTEST2(tp->th_sport, length)) {
			sum = tcp6_cksum(ip6, tp, length);
			if (sum != 0)
				(void)printf(" [bad tcp cksum %x!]", sum);
			else
				(void)printf(" [tcp sum ok]");
		}
	}
#endif

	length -= hlen;
	if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
		(void)printf(" %u:%u(%d)", seq, seq + length, length);
	if (flags & TH_ACK)
		(void)printf(" ack %u", ack);

	(void)printf(" win %d", win);

	if (flags & TH_URG)
		(void)printf(" urg %d", urp);
	/*
	 * Handle any options.
	 */
	if ((hlen -= sizeof(*tp)) > 0) {
		register const u_char *cp;
		register int i, opt, len, datalen;

		cp = (const u_char *)tp + sizeof(*tp);
		putchar(' ');
		ch = '<';
		while (hlen > 0) {
			putchar(ch);
			TCHECK(*cp);
			opt = *cp++;
			if (ZEROLENOPT(opt))
				len = 1;
			else {
				TCHECK(*cp);
				len = *cp++;	/* total including type, len */
				if (len < 2 || len > hlen)
					goto bad;
				--hlen;		/* account for length byte */
			}
			--hlen;			/* account for type byte */
			datalen = 0;

/* Bail if "l" bytes of data are not left or were not captured  */
#define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }

			switch (opt) {

			case TCPOPT_MAXSEG:
				(void)printf("mss");
				datalen = 2;
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_16BITS(cp));

				break;

			case TCPOPT_EOL:
				(void)printf("eol");
				break;

			case TCPOPT_NOP:
				(void)printf("nop");
				break;

			case TCPOPT_WSCALE:
				(void)printf("wscale");
				datalen = 1;
				LENCHECK(datalen);
				(void)printf(" %u", *cp);
				break;

			case TCPOPT_SACKOK:
				(void)printf("sackOK");
				break;

			case TCPOPT_SACK:
				(void)printf("sack");
				datalen = len - 2;
				if (datalen % 8 != 0) {
					(void)printf(" malformed sack ");
				} else {
					u_int32_t s, e;

					(void)printf(" sack %d ", datalen / 8);
					for (i = 0; i < datalen; i += 8) {
						LENCHECK(i + 4);
						s = EXTRACT_32BITS(cp + i);
						LENCHECK(i + 8);
						e = EXTRACT_32BITS(cp + i + 4);
						if (threv) {
							s -= thseq;
							e -= thseq;
						} else {
							s -= thack;
							e -= thack;
						}
						(void)printf("{%u:%u}", s, e);
					}
					(void)printf(" ");
				}
				break;

			case TCPOPT_ECHO:
				(void)printf("echo");
				datalen = 4;
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_32BITS(cp));
				break;

			case TCPOPT_ECHOREPLY:
				(void)printf("echoreply");
				datalen = 4;
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_32BITS(cp));
				break;

			case TCPOPT_TIMESTAMP:
				(void)printf("timestamp");
				datalen = 8;
				LENCHECK(4);
				(void)printf(" %u", EXTRACT_32BITS(cp));
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_32BITS(cp + 4));
				break;

			case TCPOPT_CC:
				(void)printf("cc");
				datalen = 4;
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_32BITS(cp));
				break;

			case TCPOPT_CCNEW:
				(void)printf("ccnew");
				datalen = 4;
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_32BITS(cp));
				break;

			case TCPOPT_CCECHO:
				(void)printf("ccecho");
				datalen = 4;
				LENCHECK(datalen);
				(void)printf(" %u", EXTRACT_32BITS(cp));
				break;

			default:
				(void)printf("opt-%d:", opt);
				datalen = len - 2;
				for (i = 0; i < datalen; ++i) {
					LENCHECK(i);
					(void)printf("%02x", cp[i]);
				}
				break;
			}

			/* Account for data printed */
			cp += datalen;
			hlen -= datalen;

			/* Check specification against observed length */
			++datalen;			/* option octet */
			if (!ZEROLENOPT(opt))
				++datalen;		/* size octet */
			if (datalen != len)
				(void)printf("[len %d]", len);
			ch = ',';
			if (opt == TCPOPT_EOL)
				break;
		}
		putchar('>');
	}

	if (length <= 0)
		return;

	/*
	 * Decode payload if necessary.
	 */
	bp += TH_OFF(tp) * 4;
	if (flags & TH_RST) {
		if (vflag)
			print_tcp_rst_data(bp, length);
	} else {
		if (sport == TELNET_PORT || dport == TELNET_PORT) {
			if (!qflag && vflag)
				telnet_print(bp, length);
		} else if (sport == BGP_PORT || dport == BGP_PORT)
			bgp_print(bp, length);
		else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
			nbt_tcp_print(bp, length);
		else if (sport == BXXP_PORT || dport == BXXP_PORT)
			bxxp_print(bp, length);
	}
	return;
bad:
	fputs("[bad opt]", stdout);
	if (ch != '\0')
		putchar('>');
	return;
trunc:
	fputs("[|tcp]", stdout);
	if (ch != '\0')
		putchar('>');
}

/*
 * RFC1122 says the following on data in RST segments:
 *
 *         4.2.2.12  RST Segment: RFC-793 Section 3.4
 *
 *            A TCP SHOULD allow a received RST segment to include data.
 *
 *            DISCUSSION
 *                 It has been suggested that a RST segment could contain
 *                 ASCII text that encoded and explained the cause of the
 *                 RST.  No standard has yet been established for such
 *                 data.
 *
 */

static void
print_tcp_rst_data(register const u_char *sp, u_int length)
{
	int c;

	if (TTEST2(*sp, length))
		printf(" [RST");
	else
		printf(" [!RST");
	if (length > MAX_RST_DATA_LEN) {
		length = MAX_RST_DATA_LEN;	/* can use -X for longer */
		putchar('+');			/* indicate we truncate */
	}
	putchar(' ');
	while (length-- && sp <= snapend) {
		c = *sp++;
		if (isprint(c))
			putchar(c);
		else
			putchar('.');
	}
	putchar(']');
}