// Copyright 2025 Google LLC

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//      http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

////////////////////////////////////////////////////////////////////////////////

#include <stdint.h>

#include <stddef.h>

#include <string>

#include <vector>

#include <cstring>

#include "fuzzer/FuzzedDataProvider.h"

#include "connection_helper.h"

#include "conn_tls_check.h"

#include "mempool_funcs.h"

#include "mhd_send.h"

#include "stream_process_request.h"

#include "stream_process_states.h"

// Initialising the memory pool

extern "C" int LLVMFuzzerInitialize() {

  g_pool = mhd_pool_create(g_pool_size, MHD_MEMPOOL_ZEROING_ON_RESET);

  atexit(destroy_global_pool);

  return 0;

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  if (size == 0 || g_pool == nullptr) {

    return 0;

  }

  FuzzedDataProvider fdp(data, size);

  // Reseting the memory pool for each iteartion

  mhd_pool_destroy(g_pool);

  g_pool = mhd_pool_create(g_pool_size, MHD_MEMPOOL_ZEROING_ON_RESET);

  // Initialising the daemon, connection and other MHD components

  MHD_Daemon daemon;

  MHD_Connection connection;

  init_daemon_connection(fdp, daemon, connection);

  init_parsing_configuration(fdp, connection);

  init_connection_buffer(fdp, connection);

  prepare_headers_and_parse(connection, size);

  // Randomly choose how many targets to fuzz

  std::vector<int> selectors;

  for (int i = 0; i < fdp.ConsumeIntegralInRange<int>(1, 8); i++) {

    selectors.push_back(fdp.ConsumeIntegralInRange<int>(0, 5));

  }

  // Generate random flags

  bool use_stream_body = fdp.ConsumeBool();

  bool is_nodelay = fdp.ConsumeBool();

  bool is_cork = fdp.ConsumeBool();

  // Use remaining bytes to generate random body for fuzzing

  std::string body = fdp.ConsumeRemainingBytesAsString();

  size_t body_size = body.size();

  if (body_size == 0) {

    return 0;

  }

  prepare_body_and_process(connection, body, body_size, use_stream_body);

  for (int selector : selectors) {

    switch (selector) {

      case 0: {

        mhd_conn_event_loop_state_update(&connection);

        break;

      }

      case 1: {

        if (connection.rq.app_act.head_act.act == mhd_ACTION_NO_ACTION &&

            connection.daemon && connection.daemon->req_cfg.cb) {

          mhd_stream_call_app_request_cb(&connection);

        }

        break;

      }

      case 2: {

        if (connection.rq.app_act.head_act.act == mhd_ACTION_POST_PARSE &&

            connection.rq.app_act.head_act.data.post_parse.done_cb != nullptr &&

            is_post_parse_ready(connection)) {

          mhd_stream_process_req_recv_finished(&connection);

        }

        break;

      }

      default: case 3: {

        mhd_conn_tls_check(&connection);

        break;

      }

    }

  }

  final_cleanup(connection, daemon);

  return 0;

}