/* tap-tcp-stream.c
 * TCP stream statistics
 * Originally from tcp_graph.c by Pavel Mores <pvl@uh.cz>
 * Win32 port:  rwh@unifiedtech.com
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include "config.h"


#include <stdlib.h>

#include <file.h>
#include <frame_tvbuff.h>

#include <epan/epan_dissect.h>
#include <epan/packet.h>
#include <epan/tap.h>

#include <epan/dissectors/packet-tcp.h>

#include "ui/simple_dialog.h"

#include "tap-tcp-stream.h"

typedef struct _tcp_scan_t {
    int                     direction;
    struct tcp_graph       *tg;
    struct segment         *last;
} tcp_scan_t;


static tap_packet_status
tapall_tcpip_packet(void *pct, packet_info *pinfo, epan_dissect_t *edt _U_, const void *vip, tap_flags_t flags _U_)
{
    tcp_scan_t   *ts = (tcp_scan_t *)pct;
    struct tcp_graph *tg  = ts->tg;
    const struct tcpheader *tcphdr = (const struct tcpheader *)vip;

    if (tg->stream == tcphdr->th_stream
            && (tg->src_address.type == AT_NONE || tg->dst_address.type == AT_NONE)) {
        /*
         * We only know the stream number. Fill in our connection data.
         * We assume that the server response is more interesting.
         */
        bool server_is_src;
        if (tcphdr->th_flags & TH_SYN) {
            if (tcphdr->th_flags & TH_ACK) {
                /* SYN-ACK packet, so the server is the source. */
                server_is_src = true;
            } else {
                /* SYN packet, so the server is the destination. */
                server_is_src = false;
            }
        } else {
            /* Fallback to assuming the lower numbered port is the server. */
            server_is_src = tcphdr->th_sport < tcphdr->th_dport;
        }
        if (server_is_src) {
            copy_address(&tg->src_address, &tcphdr->ip_src);
            tg->src_port = tcphdr->th_sport;
            copy_address(&tg->dst_address, &tcphdr->ip_dst);
            tg->dst_port = tcphdr->th_dport;
        } else {
            copy_address(&tg->src_address, &tcphdr->ip_dst);
            tg->src_port = tcphdr->th_dport;
            copy_address(&tg->dst_address, &tcphdr->ip_src);
            tg->dst_port = tcphdr->th_sport;
        }
    }

    if (compare_headers(&tg->src_address, &tg->dst_address,
                        tg->src_port, tg->dst_port,
                        &tcphdr->ip_src, &tcphdr->ip_dst,
                        tcphdr->th_sport, tcphdr->th_dport,
                        ts->direction)
        && tg->stream == tcphdr->th_stream)
    {
        struct segment *segment = g_new(struct segment, 1);
        segment->next      = NULL;
        segment->num       = pinfo->num;
        segment->rel_secs  = (uint32_t)pinfo->rel_ts.secs;
        segment->rel_usecs = pinfo->rel_ts.nsecs/1000;
        /* Currently unused
        segment->abs_secs  = pinfo->abs_ts.secs;
        segment->abs_usecs = pinfo->abs_ts.nsecs/1000;
        */
        /* tcphdr->th_rawseq is always the absolute sequence number.
         * tcphdr->th_seq is either the relative or absolute sequence number
         * depending on the TCP dissector preferences.
         * The sack entries are also either the relative or absolute sequence
         * number depending on the TCP dissector preferences.
         * The TCP stream graphs have their own action / button press to
         * switch between relative and absolute sequence numbers on the fly;
         * if the TCP dissector hasn't calculated the relative sequence numbers,
         * the tap will do so. (XXX - The calculation is cheap enough that we
         * could do it here and store the offsets at the graph level to save
         * memory. The TCP dissector could include its calculated base seq in
         * the tap information to ensure consistency.)
         */
        segment->th_seq    = tcphdr->th_seq;
        segment->th_ack    = tcphdr->th_ack;
        segment->th_rawseq = tcphdr->th_rawseq;
        segment->th_rawack = tcphdr->th_rawack;
        segment->th_win    = tcphdr->th_win;
        segment->th_flags  = tcphdr->th_flags;
        segment->th_sport  = tcphdr->th_sport;
        segment->th_dport  = tcphdr->th_dport;
        segment->th_seglen = tcphdr->th_seglen;
        copy_address(&segment->ip_src, &tcphdr->ip_src);
        copy_address(&segment->ip_dst, &tcphdr->ip_dst);

        segment->num_sack_ranges = MIN(MAX_TCP_SACK_RANGES, tcphdr->num_sack_ranges);
        if (segment->num_sack_ranges > 0) {
            /* Copy entries in the order they happen */
            memcpy(&segment->sack_left_edge, &tcphdr->sack_left_edge, sizeof(segment->sack_left_edge));
            memcpy(&segment->sack_right_edge, &tcphdr->sack_right_edge, sizeof(segment->sack_right_edge));
        }

        if (ts->tg->segments) {
            ts->last->next = segment;
        } else {
            ts->tg->segments = segment;
        }
        ts->last = segment;
    }

    return TAP_PACKET_DONT_REDRAW;
}

/* here we collect all the external data we will ever need */
void
graph_segment_list_get(capture_file *cf, struct tcp_graph *tg)
{
    GString    *error_string;
    tcp_scan_t  ts;

    if (!cf || !tg) {
        return;
    }

    /* rescan all the packets and pick up all interesting tcp headers.
     * we only filter for TCP here for speed and do the actual compare
     * in the tap listener
     */
    ts.direction = COMPARE_ANY_DIR;
    ts.tg      = tg;
    ts.last    = NULL;
    error_string = register_tap_listener("tcp", &ts, "tcp", 0, NULL, tapall_tcpip_packet, NULL, NULL);
    if (error_string) {
        fprintf(stderr, "wireshark: Couldn't register tcp_graph tap: %s\n",
                error_string->str);
        g_string_free(error_string, TRUE);
        exit(1);   /* XXX: fix this */
    }
    cf_retap_packets(cf);
    remove_tap_listener(&ts);
}

void
graph_segment_list_free(struct tcp_graph *tg)
{
    struct segment *segment;

    free_address(&tg->src_address);
    free_address(&tg->dst_address);

    while (tg->segments) {
        segment = tg->segments->next;
        free_address(&tg->segments->ip_src);
        free_address(&tg->segments->ip_dst);
        g_free(tg->segments);
        tg->segments = segment;
    }
}

int
compare_headers(address *saddr1, address *daddr1, uint16_t sport1, uint16_t dport1, const address *saddr2, const address *daddr2, uint16_t sport2, uint16_t dport2, int dir)
{
    int dir1, dir2;

    dir1 = ((!(cmp_address(saddr1, saddr2))) &&
            (!(cmp_address(daddr1, daddr2))) &&
            (sport1==sport2)                 &&
            (dport1==dport2));

    if (dir == COMPARE_CURR_DIR) {
        return dir1;
    } else {
        dir2 = ((!(cmp_address(saddr1, daddr2))) &&
                (!(cmp_address(daddr1, saddr2))) &&
                (sport1 == dport2)               &&
                (dport1 == sport2));
        return dir1 || dir2;
    }
}

int
get_num_dsegs(struct tcp_graph *tg)
{
    int count;
    struct segment *tmp;

    for (tmp=tg->segments, count=0; tmp; tmp=tmp->next) {
        if (compare_headers(&tg->src_address, &tg->dst_address,
                            tg->src_port, tg->dst_port,
                            &tmp->ip_src, &tmp->ip_dst,
                            tmp->th_sport, tmp->th_dport,
                            COMPARE_CURR_DIR)) {
            count++;
        }
    }
    return count;
}

int
get_num_acks(struct tcp_graph *tg, int *num_sack_ranges)
{
    int count;
    struct segment *tmp;

    for (tmp = tg->segments, count=0; tmp; tmp = tmp->next) {
        if (!compare_headers(&tg->src_address, &tg->dst_address,
                             tg->src_port, tg->dst_port,
                             &tmp->ip_src, &tmp->ip_dst,
                             tmp->th_sport, tmp->th_dport,
                             COMPARE_CURR_DIR)) {
            count++;
            *num_sack_ranges += tmp->num_sack_ranges;
        }
    }
    return count;
}

typedef struct _th_t {
    int num_hdrs;
    #define MAX_SUPPORTED_TCP_HEADERS 8
    struct tcpheader *tcphdrs[MAX_SUPPORTED_TCP_HEADERS];
} th_t;

static tap_packet_status
tap_tcpip_packet(void *pct, packet_info *pinfo _U_, epan_dissect_t *edt _U_, const void *vip, tap_flags_t flags _U_)
{
    int       n;
    bool      is_unique = true;
    th_t     *th        = (th_t *)pct;
    const struct tcpheader *header = (const struct tcpheader *)vip;

    /* Check new header details against any/all stored ones */
    for (n=0; n < th->num_hdrs; n++) {
        struct tcpheader *stored = th->tcphdrs[n];

        if (compare_headers(&stored->ip_src, &stored->ip_dst,
                            stored->th_sport, stored->th_dport,
                            &header->ip_src, &header->ip_dst,
                            header->th_sport, stored->th_dport,
                            COMPARE_CURR_DIR)) {
            is_unique = false;
            break;
        }
    }

    /* Add address if unique and have space for it */
    if (is_unique && (th->num_hdrs < MAX_SUPPORTED_TCP_HEADERS)) {
        /* Need to take a deep copy of the tap struct, it may not be valid
           to read after this function returns? */
        th->tcphdrs[th->num_hdrs] = g_new(struct tcpheader, 1);
        *(th->tcphdrs[th->num_hdrs]) = *header;
        copy_address(&th->tcphdrs[th->num_hdrs]->ip_src, &header->ip_src);
        copy_address(&th->tcphdrs[th->num_hdrs]->ip_dst, &header->ip_dst);

        th->num_hdrs++;
    }

    return TAP_PACKET_DONT_REDRAW;
}

/* XXX should be enhanced so that if we have multiple TCP layers in the trace
 * then present the user with a dialog where the user can select WHICH tcp
 * session to graph.
 */
uint32_t
select_tcpip_session(capture_file *cf)
{
    frame_data     *fdata;
    epan_dissect_t  edt;
    dfilter_t      *sfcode;
    uint32_t        th_stream;
    df_error_t     *df_err;
    GString        *error_string;
    th_t th = {0, {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}};

    if (!cf) {
        return UINT32_MAX;
    }

    /* no real filter yet */
    if (!dfilter_compile("tcp", &sfcode, &df_err)) {
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "%s", df_err->msg);
        df_error_free(&df_err);
        return UINT32_MAX;
    }

    /* dissect the current record */
    if (!cf_read_current_record(cf)) {
        return UINT32_MAX;    /* error reading the record */
    }

    fdata = cf->current_frame;

    error_string = register_tap_listener("tcp", &th, NULL, 0, NULL, tap_tcpip_packet, NULL, NULL);
    if (error_string) {
        fprintf(stderr, "wireshark: Couldn't register tcp_graph tap: %s\n",
                error_string->str);
        g_string_free(error_string, TRUE);
        exit(1);
    }

    epan_dissect_init(&edt, cf->epan, true, false);
    epan_dissect_prime_with_dfilter(&edt, sfcode);
    epan_dissect_run_with_taps(&edt, cf->cd_t, &cf->rec,
                               frame_tvbuff_new_buffer(&cf->provider, fdata, &cf->buf),
                               fdata, NULL);
    epan_dissect_cleanup(&edt);
    remove_tap_listener(&th);
    dfilter_free(sfcode);

    if (th.num_hdrs == 0) {
        /* This "shouldn't happen", as our menu items shouldn't
         * even be enabled if the selected packet isn't a TCP
         * segment, as tcp_graph_selected_packet_enabled() is used
         * to determine whether to enable any of our menu items. */
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK,
                      "Selected packet isn't a TCP segment or is truncated");
        return UINT32_MAX;
    }
    /* XXX fix this later, we should show a dialog allowing the user
       to select which session he wants here
    */
    if (th.num_hdrs > 1) {
        /* can only handle a single tcp layer yet */
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK,
                      "The selected packet has more than one TCP unique conversation "
                      "in it.");
        return UINT32_MAX;
    }

    /* For now, still always choose the first/only one */
    th_stream = th.tcphdrs[0]->th_stream;

    for (int n = 0; n < th.num_hdrs; n++) {
        free_address(&th.tcphdrs[n]->ip_src);
        free_address(&th.tcphdrs[n]->ip_dst);
        g_free(th.tcphdrs[n]);
    }

    return th_stream;
}

int rtt_is_retrans(struct rtt_unack *list, unsigned int seqno)
{
    struct rtt_unack *u;

    for (u=list; u; u=u->next) {
        if (tcp_seq_eq_or_after(seqno, u->seqno) &&
            tcp_seq_before(seqno, u->end_seqno)) {
            return true;
        }
    }
    return false;
}

struct rtt_unack *
rtt_get_new_unack(double time_val, unsigned int seqno, unsigned int seglen)
{
    struct rtt_unack *u;

    u = g_new(struct rtt_unack, 1);
    u->next  = NULL;
    u->time  = time_val;
    u->seqno = seqno;
    u->end_seqno = seqno + seglen;
    return u;
}

void rtt_put_unack_on_list(struct rtt_unack **l, struct rtt_unack *new_unack)
{
    struct rtt_unack *u, *list = *l;

    for (u=list; u; u=u->next) {
        if (!u->next) {
            break;
        }
    }
    if (u) {
        u->next = new_unack;
    } else {
        *l = new_unack;
    }
}

void rtt_delete_unack_from_list(struct rtt_unack **l, struct rtt_unack *dead)
{
    struct rtt_unack *u, *list = *l;

    if (!dead || !list) {
        return;
    }

    if (dead == list) {
        *l = list->next;
        g_free(list);
    } else {
        for (u=list; u; u=u->next) {
            if (u->next == dead) {
                u->next = u->next->next;
                g_free(dead);
                break;
            }
        }
    }
}

void rtt_destroy_unack_list(struct rtt_unack **l ) {
    while (*l) {
        struct rtt_unack *head = *l;
        *l = head->next;
        g_free(head);
    }
}