/*

 * Copyright (C) Max Dymond, <cmeister2@gmail.com>, et al.

 *

 * SPDX-License-Identifier: curl

 */

/// @file

/// @brief Implementation of ScenarioRunner::Run.

#include "proto_fuzzer/scenario_runner.h"

#include <curl/curl.h>

#include <curl/header.h>

#include <cstddef>

#include <memory>

#include <string>

#include "proto_fuzzer/api_lifecycle.h"

#include "proto_fuzzer/ftp_mock_server.h"

#include "proto_fuzzer/mock_server.h"

#include "proto_fuzzer/mock_server_base.h"

#include "proto_fuzzer/option_apply.h"

#include "proto_fuzzer/request_data.h"

#include "proto_fuzzer/telnet_mock_server.h"

#include "proto_fuzzer/tftp_mock_server.h"

#include "proto_fuzzer/websocket_mock_server.h"

#if defined(PROTO_FUZZER_HAS_TLS_MOCK_SERVER)

#include "proto_fuzzer/tls_mock_server.h"

#endif

namespace proto_fuzzer {

namespace {

/// @brief RAII wrapper for CURL* easy handles.

struct CurlEasyDeleter {

  void operator()(CURL* h) const noexcept {

    if (h) curl_easy_cleanup(h);

  }

};

using CurlEasyPtr = std::unique_ptr<CURL, CurlEasyDeleter>;

/// @brief RAII wrapper for caller-owned curl_slist option data.

struct CurlSlistDeleter {

  void operator()(curl_slist* list) const noexcept { curl_slist_free_all(list); }

};

using CurlSlistPtr = std::unique_ptr<curl_slist, CurlSlistDeleter>;

constexpr unsigned int kAllHeaderOrigins = CURLH_HEADER | CURLH_TRAILER | CURLH_CONNECT | CURLH_1XX | CURLH_PSEUDO;

constexpr std::size_t kMaxResultHeaders = 16;

/// Probe each public getinfo return family and the response-header API after

/// curl has settled the transfer. Applications commonly inspect these APIs,

/// but a harness that only drives I/O leaves their type dispatch and

/// post-transfer state unexecuted even when the corresponding parser ran.

/// The chosen values are handle-owned or scalar: notably CERTINFO exercises

/// the pointer/slist dispatch family without materialising a separately-owned

/// cookie/engine list. Header iteration is capped independently of response

/// size so this unconditional coverage cannot dominate a fuzz iteration.

void ProbeTransferResults(CURL* easy) {

  char* string_result = nullptr;

  long long_result = 0;

  double double_result = 0;

  curl_off_t offset_result = 0;

  curl_socket_t socket_result = CURL_SOCKET_BAD;

  struct curl_certinfo* certinfo_result = nullptr;

  (void)curl_easy_getinfo(easy, CURLINFO_EFFECTIVE_URL, &string_result);

  (void)curl_easy_getinfo(easy, CURLINFO_RESPONSE_CODE, &long_result);

  (void)curl_easy_getinfo(easy, CURLINFO_TOTAL_TIME, &double_result);

  (void)curl_easy_getinfo(easy, CURLINFO_SIZE_DOWNLOAD_T, &offset_result);

  (void)curl_easy_getinfo(easy, CURLINFO_ACTIVESOCKET, &socket_result);

  (void)curl_easy_getinfo(easy, CURLINFO_CERTINFO, &certinfo_result);

  struct curl_header* header = nullptr;

  (void)curl_easy_header(easy, "Content-Type", 0, kAllHeaderOrigins, -1, &header);

  header = nullptr;

  for (std::size_t index = 0; index < kMaxResultHeaders; ++index) {

    header = curl_easy_nextheader(easy, kAllHeaderOrigins, -1, header);

    if (header == nullptr) {

      break;

    }

  }

}

/// Map a Scheme enum to the URL scheme literal.

const char* SchemePrefix(curl::fuzzer::proto::Scheme scheme) {

  switch (scheme) {

    case curl::fuzzer::proto::SCHEME_HTTP:

      return "http";

    case curl::fuzzer::proto::SCHEME_HTTPS:

      return "https";

    case curl::fuzzer::proto::SCHEME_WS:

      return "ws";

    case curl::fuzzer::proto::SCHEME_WSS:

      return "wss";

    case curl::fuzzer::proto::SCHEME_TELNET:

      return "telnet";

    case curl::fuzzer::proto::SCHEME_FTP:

      return "ftp";

    case curl::fuzzer::proto::SCHEME_TFTP:

      return "tftp";

    case curl::fuzzer::proto::SCHEME_UNSPECIFIED:

    default:

      return nullptr;

  }

}

/// Pick the peer implementation authorized by both protocol and target mode.

/// The compatibility target must keep treating HTTPS response bytes as raw TLS

/// records, while the dedicated HTTPS lane interprets them as decrypted HTTP.

/// Keeping that semantic boundary in the closed run-mode enum prevents a new

/// protobuf field from silently changing old OSS-Fuzz reproducers.

std::unique_ptr<MockServerBase> MakeMockServerForScenario(const curl::fuzzer::proto::Scenario& scenario,

                                                          ScenarioRunMode mode) {

  switch (scenario.scheme()) {

    case curl::fuzzer::proto::SCHEME_HTTP:

      return std::make_unique<MockServer>();

    case curl::fuzzer::proto::SCHEME_HTTPS:

#if defined(PROTO_FUZZER_HAS_TLS_MOCK_SERVER)

      if (mode == ScenarioRunMode::kTlsCoverage) {

        return std::make_unique<TlsMockServer>();

      }

#else

      (void)mode;

#endif

      return std::make_unique<MockServer>();

    case curl::fuzzer::proto::SCHEME_WS:

    case curl::fuzzer::proto::SCHEME_WSS:

      return std::make_unique<WebSocketMockServer>();

    case curl::fuzzer::proto::SCHEME_TELNET:

      return std::make_unique<TelnetMockServer>();

    case curl::fuzzer::proto::SCHEME_FTP:

      // New numeric enum values may already occur in the historical mixed

      // corpus as unknown fields. Only the fixed FTP profile may reinterpret

      // one as a live two-channel protocol exchange.

      if (mode == ScenarioRunMode::kFtpCoverage) {

        return std::make_unique<FtpMockServer>();

      }

      return nullptr;

    case curl::fuzzer::proto::SCHEME_TFTP:

      // TFTP changes the callback transport from a preconnected stream to a

      // real UDP endpoint, so compatibility inputs must not opt into it merely

      // because this build learned a new enum value.

      if (mode == ScenarioRunMode::kTftpCoverage) {

        return std::make_unique<TftpMockServer>();

      }

      return nullptr;

    case curl::fuzzer::proto::SCHEME_UNSPECIFIED:

    default:

      return nullptr;

  }

}

}  // namespace

/// @class proto_fuzzer::ScenarioRunner

/// @brief Executes one Scenario end-to-end: applies options, picks a mock

///        server for the scheme, and hands off to the mock's DriveScenario.

///        Instances are cheap; create one per fuzz case so per-scenario state

///        is torn down cleanly.

/// Default-construct an empty runner. All state is set up inside Run().

ScenarioRunner::ScenarioRunner() = default;

/// Default destructor; per-run state is local to Run() so nothing to tear

/// down at instance scope.

ScenarioRunner::~ScenarioRunner() = default;

/// Implement the bounded orchestration contract documented on Run's public

/// declaration; keeping argument docs there avoids two drifting descriptions.

int ScenarioRunner::Run(const curl::fuzzer::proto::Scenario& scenario, ScenarioRunMode mode) {

  const char* prefix = SchemePrefix(scenario.scheme());

  if (prefix == nullptr || scenario.host_path().empty()) {

    return 0;

  }

  std::unique_ptr<MockServerBase> mock = MakeMockServerForScenario(scenario, mode);

  if (!mock) {

    return 0;

  }

  // Declaration order is an ownership invariant: reverse destruction keeps

  // CONNECT_TO storage and share callback userdata alive through easy cleanup.

  // This matters for incomplete transfers, where an explicit share detach can

  // be rejected while easy cleanup can still release the reference safely.

  std::unique_ptr<ApiLifecycle> api_lifecycle;

  CurlSlistPtr connect_to;

  CurlEasyPtr easy(curl_easy_init());

  if (!easy) {

    return 0;

  }

  std::string url = std::string(prefix) + "://" + scenario.host_path();

  const auto configure_easy = [&] {

    connect_to.reset(ApplyBaselineOptions(easy.get(), scenario.scheme()));

    curl_easy_setopt(easy.get(), CURLOPT_URL, url.c_str());

    mock->Install(easy.get());

    // Compatibility inputs deliberately bypass the mutating postprocessor,

    // so enforce the shared option prefix again at the runtime boundary. The

    // helper still ignores individual CURLcodes: the fuzzer stresses curl

    // rather than treating rejected combinations as harness failures.

    (void)ApplyScenarioOptions(easy.get(), scenario);

  };

  configure_easy();

  const curl::fuzzer::proto::ApiPlan* api_plan =

      mode == ScenarioRunMode::kApiLifecycle && scenario.has_api_plan() ? &scenario.api_plan() : nullptr;

  if (api_plan != nullptr && api_plan->reset_easy()) {

    // Reset deliberately drops every pointer-valued option before its backing

    // list is freed. Reapplying the exact scenario then lets the transfer

    // populate post-reset state instead of turning reset coverage into a

    // guaranteed malformed request.

    curl_easy_reset(easy.get());

    connect_to.reset();

    configure_easy();

  }

  if (api_plan != nullptr) {

    api_lifecycle = std::make_unique<ApiLifecycle>(easy.get(), *api_plan, url);

  }

  {

    // HTTP headers, MIME bodies, TELNET options, and callback userdata are

    // pointer-valued state that libcurl does not copy. Keep their owner around

    // the entire multi-handle drive, then let it detach them while `easy` is

    // still valid. This inner scope is deliberate: easy.reset() below must

    // never run before the owner's destructor clears those options.

    ScenarioRequestData request_data(easy.get(), scenario);

    mock->ConfigureRequestData(&request_data);

    const auto drive_mode = api_plan == nullptr ? curl::fuzzer::proto::API_DRIVE_MULTI_PERFORM : api_plan->drive_mode();

    if (drive_mode == curl::fuzzer::proto::API_DRIVE_EASY_PERFORM) {

      mock->DriveEasyScenario(easy.get(), scenario);

    } else {

      mock->DriveScenario(easy.get(), scenario, drive_mode == curl::fuzzer::proto::API_DRIVE_MULTI_SOCKET,

                          api_plan != nullptr && api_plan->wake_multi());

    }

    if (api_lifecycle != nullptr) {

      api_lifecycle->ProbeTransferResults(drive_mode == curl::fuzzer::proto::API_DRIVE_EASY_PERFORM);

      api_lifecycle->ProbeEasyDuplication();

    } else if (mode != ScenarioRunMode::kFastProtocol) {

      ProbeTransferResults(easy.get());

    }

  }

  // Easy cleanup is the reliable share-detach boundary even if the bounded

  // drive stopped with a connection attached. The lifecycle object—and thus

  // lock callback userdata—outlives it, then releases share-owned caches.

  easy.reset();

  connect_to.reset();

  api_lifecycle.reset();

  return 0;

}

}  // namespace proto_fuzzer