void
tcp_print(netdissect_options *ndo,
const u_char *bp, u_int length,
const u_char *bp2, int fragmented)
{
const struct tcphdr *tp;
const struct ip *ip;
u_char flags;
u_int hlen;
char ch;
uint16_t sport, dport, win, urp;
uint32_t seq, ack, thseq, thack;
u_int utoval;
uint16_t magic;
int rev;
const struct ip6_hdr *ip6;
ndo->ndo_protocol = "tcp";
tp = (const struct tcphdr *)bp;
ip = (const struct ip *)bp2;
if (IP_V(ip) == 6)
ip6 = (const struct ip6_hdr *)bp2;
else
ip6 = NULL;
ch = '\0';
if (!ND_TTEST_2(tp->th_dport)) {
if (ip6) {
ND_PRINT("%s > %s:",
ip6addr_string(ndo, ip6->ip6_src),
ip6addr_string(ndo, ip6->ip6_dst));
} else {
ND_PRINT("%s > %s:",
ipaddr_string(ndo, ip->ip_src),
ipaddr_string(ndo, ip->ip_dst));
}
nd_print_trunc(ndo);
return;
}
sport = GET_BE_U_2(tp->th_sport);
dport = GET_BE_U_2(tp->th_dport);
if (ip6) {
if (GET_U_1(ip6->ip6_nxt) == IPPROTO_TCP) {
ND_PRINT("%s.%s > %s.%s: ",
ip6addr_string(ndo, ip6->ip6_src),
tcpport_string(ndo, sport),
ip6addr_string(ndo, ip6->ip6_dst),
tcpport_string(ndo, dport));
} else {
ND_PRINT("%s > %s: ",
tcpport_string(ndo, sport), tcpport_string(ndo, dport));
}
} else {
if (GET_U_1(ip->ip_p) == IPPROTO_TCP) {
ND_PRINT("%s.%s > %s.%s: ",
ipaddr_string(ndo, ip->ip_src),
tcpport_string(ndo, sport),
ipaddr_string(ndo, ip->ip_dst),
tcpport_string(ndo, dport));
} else {
ND_PRINT("%s > %s: ",
tcpport_string(ndo, sport), tcpport_string(ndo, dport));
}
}
ND_TCHECK_SIZE(tp);
hlen = TH_OFF(tp) * 4;
if (hlen < sizeof(*tp)) {
ND_PRINT(" tcp %u [bad hdr length %u - too short, < %lu]",
length - hlen, hlen, (unsigned long)sizeof(*tp));
return;
}
seq = GET_BE_U_4(tp->th_seq);
ack = GET_BE_U_4(tp->th_ack);
win = GET_BE_U_2(tp->th_win);
urp = GET_BE_U_2(tp->th_urp);
if (ndo->ndo_qflag) {
ND_PRINT("tcp %u", length - hlen);
if (hlen > length) {
ND_PRINT(" [bad hdr length %u - too long, > %u]",
hlen, length);
}
return;
}
flags = GET_U_1(tp->th_flags);
ND_PRINT("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
if (!ndo->ndo_Sflag && (flags & TH_ACK)) {
/*
* Find (or record) the initial sequence numbers for
* this conversation. (we pick an arbitrary
* collating order so there's only one entry for
* both directions).
*/
rev = 0;
if (ip6) {
struct tcp_seq_hash6 *th;
struct tcp_seq_hash6 *tcp_seq_hash;
const void *src, *dst;
struct tha6 tha;
tcp_seq_hash = tcp_seq_hash6;
src = (const void *)ip6->ip6_src;
dst = (const void *)ip6->ip6_dst;
if (sport > dport)
rev = 1;
else if (sport == dport) {
if (UNALIGNED_MEMCMP(src, dst, sizeof(ip6->ip6_dst)) > 0)
rev = 1;
}
if (rev) {
UNALIGNED_MEMCPY(&tha.src, dst, sizeof(ip6->ip6_dst));
UNALIGNED_MEMCPY(&tha.dst, src, sizeof(ip6->ip6_src));
tha.port = ((u_int)dport) << 16 | sport;
} else {
UNALIGNED_MEMCPY(&tha.dst, dst, sizeof(ip6->ip6_dst));
UNALIGNED_MEMCPY(&tha.src, src, sizeof(ip6->ip6_src));
tha.port = ((u_int)sport) << 16 | dport;
}
for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
th->nxt; th = th->nxt)
if (memcmp((char *)&tha, (char *)&th->addr,
sizeof(th->addr)) == 0)
break;
if (!th->nxt || (flags & TH_SYN)) {
/* didn't find it or new conversation */
/* calloc() return used by the 'tcp_seq_hash6'
hash table: do not free() */
if (th->nxt == NULL) {
th->nxt = (struct tcp_seq_hash6 *)
calloc(1, sizeof(*th));
if (th->nxt == NULL)
(*ndo->ndo_error)(ndo,
S_ERR_ND_MEM_ALLOC,
"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 {
struct tcp_seq_hash *th;
struct tcp_seq_hash *tcp_seq_hash;
struct tha tha;
tcp_seq_hash = tcp_seq_hash4;
if (sport > dport)
rev = 1;
else if (sport == dport) {
if (UNALIGNED_MEMCMP(ip->ip_src, ip->ip_dst, sizeof(ip->ip_dst)) > 0)
rev = 1;
}
if (rev) {
UNALIGNED_MEMCPY(&tha.src, ip->ip_dst,
sizeof(ip->ip_dst));
UNALIGNED_MEMCPY(&tha.dst, ip->ip_src,
sizeof(ip->ip_src));
tha.port = ((u_int)dport) << 16 | sport;
} else {
UNALIGNED_MEMCPY(&tha.dst, ip->ip_dst,
sizeof(ip->ip_dst));
UNALIGNED_MEMCPY(&tha.src, ip->ip_src,
sizeof(ip->ip_src));
tha.port = ((u_int)sport) << 16 | dport;
}
for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
th->nxt; th = th->nxt)
if (memcmp((char *)&tha, (char *)&th->addr,
sizeof(th->addr)) == 0)
break;
if (!th->nxt || (flags & TH_SYN)) {
/* didn't find it or new conversation */
/* calloc() return used by the 'tcp_seq_hash4'
hash table: do not free() */
if (th->nxt == NULL) {
th->nxt = (struct tcp_seq_hash *)
calloc(1, sizeof(*th));
if (th->nxt == NULL)
(*ndo->ndo_error)(ndo,
S_ERR_ND_MEM_ALLOC,
"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 = rev = 0;
}
if (hlen > length) {
ND_PRINT(" [bad hdr length %u - too long, > %u]",
hlen, length);
return;
}
if (ndo->ndo_vflag && !ndo->ndo_Kflag && !fragmented) {
/* Check the checksum, if possible. */
uint16_t sum, tcp_sum;
if (IP_V(ip) == 4) {
if (ND_TTEST_LEN(tp->th_sport, length)) {
sum = tcp_cksum(ndo, ip, tp, length);
tcp_sum = GET_BE_U_2(tp->th_sum);
ND_PRINT(", cksum 0x%04x", tcp_sum);
if (sum != 0)
ND_PRINT(" (incorrect -> 0x%04x)",
in_cksum_shouldbe(tcp_sum, sum));
else
ND_PRINT(" (correct)");
}
} else if (IP_V(ip) == 6 && ip6->ip6_plen) {
if (ND_TTEST_LEN(tp->th_sport, length)) {
sum = tcp6_cksum(ndo, ip6, tp, length);
tcp_sum = GET_BE_U_2(tp->th_sum);
ND_PRINT(", cksum 0x%04x", tcp_sum);
if (sum != 0)
ND_PRINT(" (incorrect -> 0x%04x)",
in_cksum_shouldbe(tcp_sum, sum));
else
ND_PRINT(" (correct)");
}
}
}
length -= hlen;
if (ndo->ndo_vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
ND_PRINT(", seq %u", seq);
if (length > 0) {
ND_PRINT(":%u", seq + length);
}
}
if (flags & TH_ACK) {
ND_PRINT(", ack %u", ack);
}
ND_PRINT(", win %u", win);
if (flags & TH_URG)
ND_PRINT(", urg %u", urp);
/*
* Handle any options.
*/
if (hlen > sizeof(*tp)) {
const u_char *cp;
u_int i, opt, datalen;
u_int len;
hlen -= sizeof(*tp);
cp = (const u_char *)tp + sizeof(*tp);
ND_PRINT(", options [");
while (hlen > 0) {
if (ch != '\0')
ND_PRINT("%c", ch);
ND_TCHECK_1(cp);
opt = GET_U_1(cp);
cp++;
if (ZEROLENOPT(opt))
len = 1;
else {
ND_TCHECK_1(cp);
len = GET_U_1(cp);
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; ND_TCHECK_LEN(cp, l); }
ND_PRINT("%s", tok2str(tcp_option_values, "unknown-%u", opt));
switch (opt) {
case TCPOPT_MAXSEG:
datalen = 2;
LENCHECK(datalen);
ND_PRINT(" %u", GET_BE_U_2(cp));
break;
case TCPOPT_WSCALE:
datalen = 1;
LENCHECK(datalen);
ND_PRINT(" %u", GET_U_1(cp));
break;
case TCPOPT_SACK:
datalen = len - 2;
if (datalen % 8 != 0) {
ND_PRINT(" invalid sack");
} else {
uint32_t s, e;
ND_PRINT(" %u ", datalen / 8);
for (i = 0; i < datalen; i += 8) {
LENCHECK(i + 4);
s = GET_BE_U_4(cp + i);
LENCHECK(i + 8);
e = GET_BE_U_4(cp + i + 4);
if (rev) {
s -= thseq;
e -= thseq;
} else {
s -= thack;
e -= thack;
}
ND_PRINT("{%u:%u}", s, e);
}
}
break;
case TCPOPT_CC:
case TCPOPT_CCNEW:
case TCPOPT_CCECHO:
case TCPOPT_ECHO:
case TCPOPT_ECHOREPLY:
/*
* those options share their semantics.
* fall through
*/
datalen = 4;
LENCHECK(datalen);
ND_PRINT(" %u", GET_BE_U_4(cp));
break;
case TCPOPT_TIMESTAMP:
datalen = 8;
LENCHECK(datalen);
ND_PRINT(" val %u ecr %u",
GET_BE_U_4(cp),
GET_BE_U_4(cp + 4));
break;
case TCPOPT_SIGNATURE:
datalen = TCP_SIGLEN;
LENCHECK(datalen);
ND_PRINT(" ");
#ifdef HAVE_LIBCRYPTO
switch (tcp_verify_signature(ndo, ip, tp,
bp + TH_OFF(tp) * 4, length, cp)) {
case SIGNATURE_VALID:
ND_PRINT("valid");
break;
case SIGNATURE_INVALID:
nd_print_invalid(ndo);
break;
case CANT_CHECK_SIGNATURE:
ND_PRINT("can't check - ");
for (i = 0; i < TCP_SIGLEN; ++i)
ND_PRINT("%02x",
GET_U_1(cp + i));
break;
}
#else
for (i = 0; i < TCP_SIGLEN; ++i)
ND_PRINT("%02x", GET_U_1(cp + i));
#endif
break;
case TCPOPT_SCPS:
datalen = 2;
LENCHECK(datalen);
ND_PRINT(" cap %02x id %u", GET_U_1(cp),
GET_U_1(cp + 1));
break;
case TCPOPT_TCPAO:
datalen = len - 2;
/* RFC 5925 Section 2.2:
* "The Length value MUST be greater than or equal to 4."
* (This includes the Kind and Length fields already processed
* at this point.)
*/
if (datalen < 2) {
nd_print_invalid(ndo);
} else {
LENCHECK(1);
ND_PRINT(" keyid %u", GET_U_1(cp));
LENCHECK(2);
ND_PRINT(" rnextkeyid %u",
GET_U_1(cp + 1));
if (datalen > 2) {
ND_PRINT(" mac 0x");
for (i = 2; i < datalen; i++) {
LENCHECK(i + 1);
ND_PRINT("%02x",
GET_U_1(cp + i));
}
}
}
break;
case TCPOPT_EOL:
case TCPOPT_NOP:
case TCPOPT_SACKOK:
/*
* Nothing interesting.
* fall through
*/
break;
case TCPOPT_UTO:
datalen = 2;
LENCHECK(datalen);
utoval = GET_BE_U_2(cp);
ND_PRINT(" 0x%x", utoval);
if (utoval & 0x0001)
utoval = (utoval >> 1) * 60;
else
utoval >>= 1;
ND_PRINT(" %u", utoval);
break;
case TCPOPT_MPTCP:
datalen = len - 2;
LENCHECK(datalen);
if (!mptcp_print(ndo, cp-2, len, flags))
goto bad;
break;
case TCPOPT_FASTOPEN:
datalen = len - 2;
LENCHECK(datalen);
ND_PRINT(" ");
print_tcp_fastopen_option(ndo, cp, datalen, FALSE);
break;
case TCPOPT_EXPERIMENT2:
datalen = len - 2;
LENCHECK(datalen);
if (datalen < 2)
goto bad;
/* RFC6994 */
magic = GET_BE_U_2(cp);
ND_PRINT("-");
switch(magic) {
case 0xf989: /* TCP Fast Open RFC 7413 */
print_tcp_fastopen_option(ndo, cp + 2, datalen - 2, TRUE);
break;
default:
/* Unknown magic number */
ND_PRINT("%04x", magic);
break;
}
break;
default:
datalen = len - 2;
if (datalen)
ND_PRINT(" 0x");
for (i = 0; i < datalen; ++i) {
LENCHECK(i + 1);
ND_PRINT("%02x", GET_U_1(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)
ND_PRINT("[len %u]", len);
ch = ',';
if (opt == TCPOPT_EOL)
break;
}
ND_PRINT("]");
}
void
tcp_print(const u_char *bp, u_int length, const u_char *bp2)
{
const struct tcphdr *tp;
const struct ip *ip;
u_char flags;
int hlen;
char ch;
struct tcp_seq_hash *th = NULL;
int rev = 0;
u_int16_t sport, dport, win, urp;
tcp_seq seq, ack;
#ifdef INET6
const struct ip6_hdr *ip6;
#endif
tp = (struct tcphdr *)bp;
switch (((struct ip *)bp2)->ip_v) {
case 4:
ip = (struct ip *)bp2;
#ifdef INET6
ip6 = NULL;
#endif
break;
#ifdef INET6
case 6:
ip = NULL;
ip6 = (struct ip6_hdr *)bp2;
break;
#endif
default:
(void)printf("invalid ip version");
return;
}
ch = '\0';
if (length < sizeof(*tp)) {
(void)printf("truncated-tcp %u", length);
return;
}
if (!TTEST(tp->th_dport)) {
#ifdef INET6
if (ip6) {
(void)printf("%s > %s: [|tcp]",
ip6addr_string(&ip6->ip6_src),
ip6addr_string(&ip6->ip6_dst));
} else
#endif /*INET6*/
{
(void)printf("%s > %s: [|tcp]",
ipaddr_string(&ip->ip_src),
ipaddr_string(&ip->ip_dst));
}
return;
}
sport = ntohs(tp->th_sport);
dport = ntohs(tp->th_dport);
#ifdef INET6
if (ip6) {
if (ip6->ip6_nxt == IPPROTO_TCP) {
(void)printf("%s.%s > %s.%s: ",
ip6addr_string(&ip6->ip6_src),
tcpport_string(sport),
ip6addr_string(&ip6->ip6_dst),
tcpport_string(dport));
} else {
(void)printf("%s > %s: ",
tcpport_string(sport), tcpport_string(dport));
}
} else
#endif /*INET6*/
{
if (ip->ip_p == IPPROTO_TCP) {
(void)printf("%s.%s > %s.%s: ",
ipaddr_string(&ip->ip_src),
tcpport_string(sport),
ipaddr_string(&ip->ip_dst),
tcpport_string(dport));
} else {
(void)printf("%s > %s: ",
tcpport_string(sport), tcpport_string(dport));
}
}
if (!qflag && TTEST(tp->th_seq) && !TTEST(tp->th_ack))
(void)printf("%u ", ntohl(tp->th_seq));
TCHECK(*tp);
seq = ntohl(tp->th_seq);
ack = ntohl(tp->th_ack);
win = ntohs(tp->th_win);
urp = ntohs(tp->th_urp);
hlen = tp->th_off * 4;
if (qflag) {
(void)printf("tcp %d", length - tp->th_off * 4);
return;
} else if (packettype != PT_TCP) {
/*
* If data present and NFS port used, assume NFS.
* Pass offset of data plus 4 bytes for RPC TCP msg length
* to NFS print routines.
*/
u_int len = length - hlen;
if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
dport == NFS_PORT) {
nfsreq_print((u_char *)tp + hlen + 4, len, bp2);
return;
} else if ((u_char *)tp + 4 +
sizeof(struct rpc_msg) <= snapend && sport == NFS_PORT) {
nfsreply_print((u_char *)tp + hlen + 4, len, bp2);
return;
}
}
if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
TH_ECNECHO|TH_CWR)) {
if (flags & TH_SYN)
putchar('S');
if (flags & TH_FIN)
putchar('F');
if (flags & TH_RST)
putchar('R');
if (flags & TH_PUSH)
putchar('P');
if (flags & TH_CWR)
putchar('W'); /* congestion _W_indow reduced (ECN) */
if (flags & TH_ECNECHO)
putchar('E'); /* ecn _E_cho sent (ECN) */
} else
putchar('.');
if (!Sflag && (flags & TH_ACK)) {
struct tha tha;
/*
* Find (or record) the initial sequence numbers for
* this conversation. (we pick an arbitrary
* collating order so there's only one entry for
* both directions).
*/
#ifdef INET6
bzero(&tha, 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
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 = 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;
}
}
hlen = tp->th_off * 4;
if (hlen > length) {
(void)printf(" [bad hdr length]");
return;
}
if (ip && ip->ip_v == 4 && vflag) {
if (TTEST2(tp->th_sport, length)) {
u_int16_t sum, tcp_sum;
sum = tcp_cksum(ip, tp, length);
if (sum != 0) {
tcp_sum = EXTRACT_16BITS(&tp->th_sum);
(void)printf(" [bad tcp cksum %x! -> %x]", tcp_sum,
in_cksum_shouldbe(tcp_sum, sum));
} else
(void)printf(" [tcp sum ok]");
}
}
#ifdef INET6
if (ip6 && ip6->ip6_plen && vflag) {
if (TTEST2(tp->th_sport, length)) {
u_int16_t sum, tcp_sum;
sum = tcp6_cksum(ip6, tp, length);
if (sum != 0) {
tcp_sum = EXTRACT_16BITS(&tp->th_sum);
(void)printf(" [bad tcp cksum %x! -> %x]", tcp_sum,
in_cksum_shouldbe(tcp_sum, sum));
} else
(void)printf(" [tcp sum ok]");
}
}
#endif
/* OS Fingerprint */
if (oflag && (flags & (TH_SYN|TH_ACK)) == TH_SYN) {
struct pf_osfp_enlist *head = NULL;
struct pf_osfp_entry *fp;
unsigned long left;
left = (unsigned long)(snapend - (const u_char *)tp);
if (left >= hlen)
head = pf_osfp_fingerprint_hdr(ip, ip6, tp);
if (head) {
int prev = 0;
printf(" (src OS:");
SLIST_FOREACH(fp, head, fp_entry) {
if (fp->fp_enflags & PF_OSFP_EXPANDED)
continue;
if (prev)
printf(",");
printf(" %s", fp->fp_class_nm);
if (fp->fp_version_nm[0])
printf(" %s", fp->fp_version_nm);
if (fp->fp_subtype_nm[0])
printf(" %s", fp->fp_subtype_nm);
prev = 1;
}
printf(")");
} else {
if (left < hlen)
printf(" (src OS: short-pkt)");
else
printf(" (src OS: unknown)");
}
}
