/*

 * Copyright (C) 2026 Teluu Inc. (http://www.teluu.com)

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <stdio.h>

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

#include <pjlib.h>

#include <pjlib-util.h>

#include <pjsip.h>

pjsip_endpoint *endpt;

pj_caching_pool caching_pool;

pjsip_transport *loop_transport;

#define POOL_SIZE 8000

#define PJSIP_TEST_MEM_SIZE (2*1024*1024)

static pjsip_module dialog_test_mod;

static char* alloc_str_from_data(pj_pool_t *pool, const uint8_t *data,

                                  size_t offset, size_t len)

{

    char *buf = (char*)pj_pool_alloc(pool, len + 1);

    pj_memcpy(buf, data + offset, len);

    buf[len] = '\0';

    return buf;

}

static void test_uac_dialog(pj_pool_t *pool, const uint8_t *data, size_t size)

{

    pj_ssize_t len1, len2, len3;

    pj_str_t local_uri, remote_uri, target;

    pjsip_dialog *dlg;

    pj_status_t status;

    pjsip_tx_data *tdata;

    char *route_data;

    pj_str_t route_name;

    pjsip_hdr *hdr;

    pjsip_route_hdr route_set;

    pjsip_route_hdr *route_hdr;

    if (size < 3)

        return;

    /* Split input data into three URI strings */

    len1 = (size / 3 > 50) ? 50 : size / 3;

    len2 = (size / 3 > 50) ? 50 : size / 3;

    len3 = (size - len1 - len2 > 50) ? 50 : size - len1 - len2;

    local_uri.ptr = alloc_str_from_data(pool, data, 0, len1);

    local_uri.slen = len1;

    remote_uri.ptr = alloc_str_from_data(pool, data, len1, len2);

    remote_uri.slen = len2;

    target.ptr = alloc_str_from_data(pool, data, len1 + len2, len3);

    target.slen = len3;

    /* Create UAC dialog */

    dlg = NULL;

    status = pjsip_dlg_create_uac(pjsip_ua_instance(), &local_uri,

                                   NULL, &remote_uri, &target, &dlg);

    if (status != PJ_SUCCESS || !dlg)

        return;

    pjsip_dlg_inc_lock(dlg);

    /* Parse and set route header from fuzzer data */

    if (size > 150) {

        route_data = alloc_str_from_data(pool, data, 150, size - 150);

        route_name = pj_str("Route");

        hdr = (pjsip_hdr*)pjsip_parse_hdr(pool, &route_name,

                                           route_data, size - 150, NULL);

        if (hdr && hdr->type == PJSIP_H_ROUTE) {

            route_hdr = (pjsip_route_hdr*)hdr;

            pj_list_init(&route_set);

            pj_list_push_back(&route_set, route_hdr);

            pjsip_dlg_set_route_set(dlg, &route_set);

        }

    }

    /* Create request within dialog */

    tdata = NULL;

    status = pjsip_dlg_create_request(dlg, &pjsip_options_method, -1, &tdata);

    if (status == PJ_SUCCESS && tdata)

        pjsip_tx_data_dec_ref(tdata);

    /* Test session management */

    pjsip_dlg_inc_session(dlg, &dialog_test_mod);

    pjsip_dlg_dec_session(dlg, &dialog_test_mod);

    pjsip_dlg_dec_lock(dlg);

}

static void test_uas_dialog(pj_pool_t *pool, const uint8_t *data, size_t size)

{

    char *data_copy;

    pjsip_parser_err_report err_list;

    pjsip_msg *msg;

    pjsip_rx_data rdata;

    pjsip_dialog *dlg;

    pj_status_t status;

    pjsip_tx_data *tdata;

    pjsip_transaction *tsx;

    pj_time_val timeout;

    if (size < 1)

        return;

    /* Parse input data as SIP message */

    data_copy = alloc_str_from_data(pool, data, 0, size);

    pj_list_init(&err_list);

    msg = pjsip_parse_msg(pool, data_copy, size, &err_list);

    if (!msg || msg->type != PJSIP_REQUEST_MSG)

        return;

    /* Setup received message structure */

    pj_bzero(&rdata, sizeof(rdata));

    rdata.msg_info.msg = msg;

    rdata.tp_info.pool = pool;

    rdata.tp_info.transport = loop_transport;

    rdata.msg_info.via = (pjsip_via_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_VIA, NULL);

    rdata.msg_info.from = (pjsip_from_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_FROM, NULL);

    rdata.msg_info.to = (pjsip_to_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_TO, NULL);

    rdata.msg_info.cseq = (pjsip_cseq_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_CSEQ, NULL);

    rdata.msg_info.cid = (pjsip_cid_hdr*)pjsip_msg_find_hdr(msg, PJSIP_H_CALL_ID, NULL);

    /* Validate required headers */

    if (!rdata.msg_info.via || !rdata.msg_info.from || !rdata.msg_info.to ||

        !rdata.msg_info.cseq || !rdata.msg_info.cid || !rdata.msg_info.cid->id.slen)

        return;

    /* Set recvd_param required by PJSIP transport layer */

    if (rdata.msg_info.via->recvd_param.slen == 0)

        rdata.msg_info.via->recvd_param = pj_str("127.0.0.1");

    /* Skip if method doesn't create a dialog */

    if (!pjsip_method_creates_dialog(&msg->line.req.method))

        return;

    /* Skip if To tag already exists */

    if (rdata.msg_info.to->tag.slen != 0)

        return;

    /* Create UAS dialog from incoming request */

    dlg = NULL;

    status = pjsip_dlg_create_uas_and_inc_lock(pjsip_ua_instance(),

                                                &rdata, NULL, &dlg);

    if (status != PJ_SUCCESS || !dlg)

        return;

    /* Create response within dialog */

    tdata = NULL;

    status = pjsip_dlg_create_response(dlg, &rdata, 200, NULL, &tdata);

    if (status == PJ_SUCCESS && tdata)

        pjsip_tx_data_dec_ref(tdata);

    /* Test session management */

    pjsip_dlg_inc_session(dlg, &dialog_test_mod);

    pjsip_dlg_dec_session(dlg, &dialog_test_mod);

    /* Terminate the transaction to prevent memory leak */

    tsx = pjsip_rdata_get_tsx(&rdata);

    if (tsx && tsx->state != PJSIP_TSX_STATE_TERMINATED)

        pjsip_tsx_terminate(tsx, 500);

    pjsip_dlg_dec_lock(dlg);

    /* Process events to cleanup terminated transactions */

    timeout.sec = 0;

    timeout.msec = 0;

    pjsip_endpt_handle_events(endpt, &timeout);

}

int LLVMFuzzerInitialize(int *argc, char ***argv)

{

    pj_status_t status;

    PJ_UNUSED_ARG(argc);

    PJ_UNUSED_ARG(argv);

    /* Initialize PJLIB */

    status = pj_init();

    if (status != PJ_SUCCESS)

        return 1;

    /* Initialize memory pool factory */

    pj_caching_pool_init(&caching_pool, &pj_pool_factory_default_policy,

                         PJSIP_TEST_MEM_SIZE);

    /* Create SIP endpoint */

    status = pjsip_endpt_create(&caching_pool.factory, "dialog-fuzzer", &endpt);

    if (status != PJ_SUCCESS)

        return 1;

    /* Initialize transaction layer */

    status = pjsip_tsx_layer_init_module(endpt);

    if (status != PJ_SUCCESS)

        return 1;

    /* Initialize UA layer */

    status = pjsip_ua_init_module(endpt, NULL);

    if (status != PJ_SUCCESS)

        return 1;

    /* Initialize loop transport */

    status = pjsip_loop_start(endpt, &loop_transport);

    if (status != PJ_SUCCESS)

        return 1;

    /* Register dialog test module */

    pj_bzero(&dialog_test_mod, sizeof(dialog_test_mod));

    dialog_test_mod.name = pj_str("dialog-test-mod");

    dialog_test_mod.id = -1;

    dialog_test_mod.priority = PJSIP_MOD_PRIORITY_APPLICATION;

    status = pjsip_endpt_register_module(endpt, &dialog_test_mod);

    if (status != PJ_SUCCESS)

        return 1;

    /* Disable logging for performance */

    pj_log_set_level(0);

    return 0;

}

int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)

{

    pj_pool_t *pool;

    pj_time_val timeout;

    /* Create pool for this iteration */

    pool = pjsip_endpt_create_pool(endpt, "dialog-fuzz", POOL_SIZE, POOL_SIZE);

    if (!pool)

        return 0;

    /* Test both UAC and UAS dialog creation */

    test_uac_dialog(pool, Data, Size);

    test_uas_dialog(pool, Data, Size);

    /* Release pool */

    pjsip_endpt_release_pool(endpt, pool);

    /* Final cleanup of any pending events */

    timeout.sec = 0;

    timeout.msec = 0;

    pjsip_endpt_handle_events(endpt, &timeout);

    return 0;

}