/*      $OpenBSD: print-tcp.c,v 1.39 2020/01/24 22:46:37 procter Exp $  */

/*
 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <sys/time.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <net/if.h>
#include <net/pfvar.h>

#include <rpc/rpc.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "interface.h"
#include "addrtoname.h"
#include "extract.h"

#include "nfs.h"

static void print_tcp_rst_data(const u_char *sp, u_int length);

#define MAX_RST_DATA_LEN        30

/* Compatibility */
#ifndef TCPOPT_WSCALE
#define TCPOPT_WSCALE           3       /* window scale factor (rfc1072) */
#endif
#ifndef TCPOPT_SACKOK
#define TCPOPT_SACKOK           4       /* selective ack ok (rfc2018) */
#endif
#ifndef TCPOPT_SACK
#define TCPOPT_SACK             5       /* selective ack (rfc2018) */
#endif
#ifndef TCPOLEN_SACK
#define TCPOLEN_SACK            8       /* length of a SACK block */
#endif
#ifndef TCPOPT_ECHO
#define TCPOPT_ECHO             6       /* echo (rfc1072) */
#endif
#ifndef TCPOPT_ECHOREPLY
#define TCPOPT_ECHOREPLY        7       /* echo (rfc1072) */
#endif
#ifndef TCPOPT_TIMESTAMP
#define TCPOPT_TIMESTAMP        8       /* timestamps (rfc1323) */
#endif
#ifndef TCPOPT_CC
#define TCPOPT_CC               11      /* T/TCP CC options (rfc1644) */
#endif
#ifndef TCPOPT_CCNEW
#define TCPOPT_CCNEW            12      /* T/TCP CC options (rfc1644) */
#endif
#ifndef TCPOPT_CCECHO
#define TCPOPT_CCECHO           13      /* T/TCP CC options (rfc1644) */
#endif

/* Definitions required for ECN
   for use if the OS running tcpdump does not have ECN */
#ifndef TH_ECNECHO
#define TH_ECNECHO              0x40    /* ECN Echo in tcp header */
#endif
#ifndef TH_CWR
#define TH_CWR                  0x80    /* ECN Cwnd Reduced in tcp header*/
#endif

struct tha {
        struct in6_addr src;
        struct in6_addr dst;
        u_int port;
};

struct tcp_seq_hash {
        struct tcp_seq_hash *nxt;
        struct tha addr;
        tcp_seq seq;
        tcp_seq ack;
};

#define TSEQ_HASHSIZE 919

/* These tcp optinos do not have the size octet */
#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)

static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];

#ifndef BGP_PORT
#define BGP_PORT        179
#endif
#define NETBIOS_SSN_PORT 139

/* OpenFlow TCP ports. */
#define OLD_OFP_PORT    6633
#define OFP_PORT        6653

static int tcp_cksum(const struct ip *ip, const struct tcphdr *tp, int len)
{
        union phu {
                struct phdr {
                        u_int32_t src;
                        u_int32_t dst;
                        u_char mbz;
                        u_char proto;
                        u_int16_t len;
                } ph;
                u_int16_t pa[6];
        } phu;
        const u_int16_t *sp;
        u_int32_t sum;

        /* pseudo-header.. */
        phu.ph.len = htons((u_int16_t)len);
        phu.ph.mbz = 0;
        phu.ph.proto = IPPROTO_TCP;
        memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
        memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));

        sp = &phu.pa[0];
        sum = sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5];

        return in_cksum((u_short *)tp, len, sum);
}

static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
                      u_int len)
{
        union {
                struct {
                        struct in6_addr ph_src;
                        struct in6_addr ph_dst;
                        u_int32_t       ph_len;
                        u_int8_t        ph_zero[3];
                        u_int8_t        ph_nxt;
                } ph;
                u_int16_t pa[20];
        } phu;
        size_t i;
        u_int32_t sum = 0;

        /* pseudo-header */
        memset(&phu, 0, sizeof(phu));
        phu.ph.ph_src = ip6->ip6_src;
        phu.ph.ph_dst = ip6->ip6_dst;
        phu.ph.ph_len = htonl(len);
        phu.ph.ph_nxt = IPPROTO_TCP;

        for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
                sum += phu.pa[i];

        return in_cksum((u_short *)tp, len, sum);
}

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;
        const struct ip6_hdr *ip6;

        tp = (struct tcphdr *)bp;
        switch (((struct ip *)bp2)->ip_v) {
        case 4:
                ip = (struct ip *)bp2;
                ip6 = NULL;
                break;
        case 6:
                ip = NULL;
                ip6 = (struct ip6_hdr *)bp2;
                break;
        default:
                printf("invalid ip version");
                return;
        }

        ch = '\0';
        if (length < sizeof(*tp)) {
                printf("truncated-tcp %u", length);
                return;
        }

        if (!TTEST(tp->th_dport)) {
                if (ip6) {
                        printf("%s > %s: [|tcp]",
                            ip6addr_string(&ip6->ip6_src),
                            ip6addr_string(&ip6->ip6_dst));
                } else {
                        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);

        if (ip6) {
                if (ip6->ip6_nxt == IPPROTO_TCP) {
                        printf("%s.%s > %s.%s: ",
                            ip6addr_string(&ip6->ip6_src),
                            tcpport_string(sport),
                            ip6addr_string(&ip6->ip6_dst),
                            tcpport_string(dport));
                } else {
                        printf("%s > %s: ",
                            tcpport_string(sport), tcpport_string(dport));
                }
        } else {
                if (ip->ip_p == IPPROTO_TCP) {
                        printf("%s.%s > %s.%s: ",
                            ipaddr_string(&ip->ip_src),
                            tcpport_string(sport),
                            ipaddr_string(&ip->ip_dst),
                            tcpport_string(dport));
                } else {
                        printf("%s > %s: ",
                            tcpport_string(sport), tcpport_string(dport));
                }
        }

        if (!qflag && TTEST(tp->th_seq) && !TTEST(tp->th_ack))
                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) {
                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).
                 */
                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;
                        }
                }

                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) {
                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);
                                printf(" [bad tcp cksum %x! -> %x]", tcp_sum,
                                    in_cksum_shouldbe(tcp_sum, sum));
                        } else
                                printf(" [tcp sum ok]");
                }
        }
        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);
                                printf(" [bad tcp cksum %x! -> %x]", tcp_sum,
                                    in_cksum_shouldbe(tcp_sum, sum));
                        } else
                                printf(" [tcp sum ok]");
                }
        }

        /* 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)");
                }
        }

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

        printf(" win %u", win);

        if (flags & TH_URG)
                printf(" urg %u", urp);
        /*
         * Handle any options.
         */
        if ((hlen -= sizeof(*tp)) > 0) {
                const u_char *cp;
                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:
                                printf("mss");
                                datalen = 2;
                                LENCHECK(datalen);
                                printf(" %u", EXTRACT_16BITS(cp));

                                break;

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

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

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

                        case TCPOPT_SACKOK:
                                printf("sackOK");
                                if (len != 2)
                                        printf("[len %d]", len);
                                break;

                        case TCPOPT_SACK:
                        {
                                u_long s, e;

                                datalen = len - 2;
                                if ((datalen % TCPOLEN_SACK) != 0 ||
                                    !(flags & TH_ACK)) {
                                         printf("malformed sack ");
                                         printf("[len %d] ", datalen);
                                         break;
                                }
                                printf("sack %d ", datalen/TCPOLEN_SACK);
                                for (i = 0; i < datalen; i += TCPOLEN_SACK) {
                                        LENCHECK (i + TCPOLEN_SACK);
                                        s = EXTRACT_32BITS(cp + i);
                                        e = EXTRACT_32BITS(cp + i + 4);
                                        if (!Sflag) {
                                                if (rev) {
                                                        s -= th->seq;
                                                        e -= th->seq;
                                                } else {
                                                        s -= th->ack;
                                                        e -= th->ack;
                                                }
                                        }
                                        printf("{%lu:%lu} ", s, e);
                                }
                                break;
                        }
                        case TCPOPT_ECHO:
                                printf("echo");
                                datalen = 4;
                                LENCHECK(datalen);
                                printf(" %u", EXTRACT_32BITS(cp));
                                break;

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

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

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

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

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

                        case TCPOPT_SIGNATURE:
                                printf("tcpmd5:");
                                datalen = len - 2;
                                for (i = 0; i < datalen; ++i) {
                                        LENCHECK(i+1);
                                        printf("%02x", cp[i]);
                                }
                                break;

                        default:
                                printf("opt-%d:", opt);
                                datalen = len - 2;
                                for (i = 0; i < datalen; ++i) {
                                        LENCHECK(i+1);
                                        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)
                                printf("[len %d]", len);
                        ch = ',';
                        if (opt == TCPOPT_EOL)
                                break;
                }
                putchar('>');
        }

        if (length <= 0)
                return;

        /*
         * Decode payload if necessary.
        */
        bp += (tp->th_off * 4);
        if (flags & TH_RST) {
                if (vflag)
                        print_tcp_rst_data(bp, length);
        } else {
                if (sport == BGP_PORT || dport == BGP_PORT)
                        bgp_print(bp, length);
                else if (sport == OLD_OFP_PORT || dport == OLD_OFP_PORT ||
                    sport == OFP_PORT || dport == OFP_PORT)
                        ofp_print(bp, length);
#if 0
                else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
                        nbt_tcp_print(bp, length);
#endif
        }
        return;
bad:
        printf("[bad opt]");
        if (ch != '\0')
                putchar('>');
        return;
trunc:
        printf("[|tcp]");
        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(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++;
                safeputchar(c);
        }
        putchar(']');
}