/*

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

 *

 * SPDX-License-Identifier: curl

 */

/// @file

/// @brief Implementation of the option-translation helpers declared in

///        option_apply.h.

#include "proto_fuzzer/option_apply.h"

#include <algorithm>

#include <cstddef>

#include <cstdint>

#include <cstdio>

#include <cstdlib>

#include <string>

#include "proto_fuzzer/scenario_limits.h"

namespace proto_fuzzer {

/// How a SetOption oneof should be decoded before calling curl_easy_setopt.

enum class OptionValueKind {

  kString,  ///< string_value → const char* option.

  kUint,    ///< uint_value → long or curl_off_t option.

  kBool     ///< bool_value → 0/1 long option.

};

/// One row in the build-time-generated option manifest: binds a proto enum

/// value to the matching curl_easy_setopt option id and value kind.

struct OptionDescriptor {

  /// Proto enum identifier for this option.

  curl::fuzzer::proto::CurlOptionId id;

  /// How the oneof value should be decoded.

  OptionValueKind kind;

  /// Human-readable option name (e.g. "CURLOPT_URL") for diagnostics.

  const char* name;

  /// The native CURLoption to pass to curl_easy_setopt.

  CURLoption curlopt;

};

// Pulls in kOptionManifest[] and its generated switch-based lookup.

#include "curl_fuzzer_option_manifest.inc"

namespace {

constexpr char kEventDrivenProtocolsAllowed[] = "http,https,ws,wss";

constexpr char kTelnetProtocolAllowed[] = "telnet";

constexpr char kFtpProtocolAllowed[] = "ftp";

constexpr char kTftpProtocolAllowed[] = "tftp";

constexpr char kConnectToOverride[] = "::127.0.1.127:";

constexpr char kDevNull[] = "/dev/null";

constexpr char kVerboseEnvVar[] = "FUZZ_VERBOSE";

constexpr char kAltSvcHttpEnvVar[] = "CURL_ALTSVC_HTTP";

constexpr char kHstsHttpEnvVar[] = "CURL_HSTS_HTTP";

constexpr long kConnectTimeoutMs = 200;

constexpr long kTimeoutMs = 200;

/// Test the same prefix curl uses to choose between an in-memory digest and a

/// filename. Do not reject malformed base64 here: those values are useful TLS

/// parser inputs and remain filesystem-safe as long as this prefix is intact.

bool UsesInMemoryPublicKeyPin(const std::string& value) { return value.rfind("sha256//", 0) == 0; }

/// Keep mutated pin values on curl's digest-comparison branch while retaining

/// every mutation byte. Existing expressions, including correlated corpus

/// seeds, must remain byte-for-byte stable.

void ConstrainPinnedPublicKeyValue(std::string* value) {

  if (value == nullptr || UsesInMemoryPublicKeyPin(*value)) {

    return;

  }

  value->insert(0, "sha256//");

}

/// Baseline write callback for both CURLOPT_WRITEFUNCTION and

/// CURLOPT_HEADERFUNCTION. Consumes every byte so transfers don't stall on

/// backpressure and emits nothing. Protocol-specific mocks may install their

/// own WRITEFUNCTION afterwards if they need to poke protocol APIs while

/// inside a curl callback.

size_t SilentWriteCallback(void* /*contents*/, size_t size, size_t nmemb, void* /*userdata*/) { return size * nmemb; }

/// Consume libcurl's verbose records without emitting per-input diagnostics.

/// TELNET's debug build keeps its negotiation/suboption formatters behind the

/// verbose switch, so the protocol lane uses this sink to make that reachable

/// code fuzzable without turning millions of iterations into log traffic.

int SilentDebugCallback(CURL* /*handle*/, curl_infotype /*type*/, char* /*data*/, size_t /*size*/, void* /*userdata*/) {

  return 0;

}

/// Let curl's debug build accept transport-security response headers over the

/// plaintext HTTP mock. The HTTPS lane now provides a verified peer, but making

/// HSTS and Alt-Svc parser coverage depend on a cryptographic handshake would

/// needlessly remove those parsers from the high-throughput HTTP lane.

void EnableDebugHttpTransportMetadata() {

  static const bool configured = [] {

    // CMake builds the fuzzing copy of curl with ENABLE_DEBUG specifically so

    // these curl-provided test hooks are available. Do not overwrite values a

    // reproducer deliberately supplied in its environment.

    (void)setenv(kAltSvcHttpEnvVar, "1", 0);

    (void)setenv(kHstsHttpEnvVar, "1", 0);

    return true;

  }();

  (void)configured;

}

void EnableTraceIds() {

  static const bool enabled = curl_global_trace("+LIB-IDS") == CURLE_OK;

  (void)enabled;

}

/// Decode protobuf's two integral oneof members according to the semantic

/// kind in the generated option descriptor. The schema cannot couple an

/// option id to one particular oneof member, so both retained corpus entries

/// and ordinary mutations can represent a flag as uint_value or a numeric

/// mode as bool_value. Preserving magnitude for numeric options and reducing

/// flags to truthiness keeps either representation useful without embedding

/// option-specific history in the runtime. String or unset members map to the

/// same zero default protobuf's inactive scalar accessors historically gave.

std::uint64_t DecodeIntegralValue(const OptionDescriptor& descriptor, const curl::fuzzer::proto::SetOption& option) {

  if (descriptor.kind == OptionValueKind::kString) {

    return 0;

  }

  switch (option.value_case()) {

    case curl::fuzzer::proto::SetOption::kBoolValue:

      return option.bool_value() ? 1U : 0U;

    case curl::fuzzer::proto::SetOption::kUintValue:

      if (descriptor.kind == OptionValueKind::kBool) {

        return option.uint_value() != 0 ? 1U : 0U;

      }

      return option.uint_value();

    case curl::fuzzer::proto::SetOption::kStringValue:

    case curl::fuzzer::proto::SetOption::VALUE_NOT_SET:

      return 0;

  }

  return 0;

}

}  // namespace

/// Decode a recognized integral option using its generated semantic kind.

/// Unknown and string-valued options have no integral interpretation and

/// therefore return zero.

std::uint64_t DecodeIntegralOptionValue(const curl::fuzzer::proto::SetOption& option) {

  const OptionDescriptor* descriptor = LookupOptionDescriptor(option.option_id());

  if (descriptor == nullptr || descriptor->kind == OptionValueKind::kString) {

    return 0;

  }

  return DecodeIntegralValue(*descriptor, option);

}

/// Make every supported option's expected oneof member explicit. Boolean and

/// integer representations retain their scalar meaning when crossing between

/// those families; string or unset mismatches become the destination family's

/// zero value. This focuses later mutations on a value ApplySetOption consumes

/// without requiring option-specific compatibility rules.

void CanonicalizeOptionValueCases(curl::fuzzer::proto::Scenario* scenario) {

  if (scenario == nullptr) {

    return;

  }

  for (auto& option : *scenario->mutable_options()) {

    const OptionDescriptor* desc = LookupOptionDescriptor(option.option_id());

    if (desc == nullptr) {

      continue;

    }

    switch (desc->kind) {

      case OptionValueKind::kString:

        if (option.value_case() != curl::fuzzer::proto::SetOption::kStringValue) {

          option.set_string_value("");

        }

        if (desc->curlopt == CURLOPT_PINNEDPUBLICKEY) {

          ConstrainPinnedPublicKeyValue(option.mutable_string_value());

        }

        break;

      case OptionValueKind::kUint:

        if (option.value_case() != curl::fuzzer::proto::SetOption::kUintValue) {

          option.set_uint_value(DecodeIntegralValue(*desc, option));

        }

        break;

      case OptionValueKind::kBool:

        if (option.value_case() != curl::fuzzer::proto::SetOption::kBoolValue) {

          option.set_bool_value(DecodeIntegralValue(*desc, option) != 0);

        }

        break;

    }

  }

}

/// Apply the fixed baseline options the harness always wants: output sinks,

/// protocol restrictions, DNS overrides, timeouts. Call before applying any

/// scenario options.

/// @param easy The curl easy handle to configure.

/// @param scheme Protocol whose dedicated in-process mock will service it.

/// @return the curl_slist owned by the caller (for CURLOPT_CONNECT_TO), which

///         must be freed with curl_slist_free_all after curl_easy_cleanup.

struct curl_slist* ApplyBaselineOptions(CURL* easy, curl::fuzzer::proto::Scheme scheme, bool trace_ids) {

  EnableDebugHttpTransportMetadata();

  curl_easy_setopt(easy, CURLOPT_WRITEFUNCTION, &SilentWriteCallback);

  curl_easy_setopt(easy, CURLOPT_HEADERFUNCTION, &SilentWriteCallback);

  const bool user_requested_verbose = std::getenv(kVerboseEnvVar) != nullptr;

  if (trace_ids) {

    EnableTraceIds();

    // Keep trace-ID coverage enabled during fuzzing without flooding the

    // process log. The callback still executes curl_trc.c's formatting path.

    curl_easy_setopt(easy, CURLOPT_DEBUGFUNCTION, &SilentDebugCallback);

    curl_easy_setopt(easy, CURLOPT_VERBOSE, 1L);

  } else if (scheme == curl::fuzzer::proto::SCHEME_TELNET && !user_requested_verbose) {

    // printoption() and printsub() contain a substantial part of curl's TELNET

    // parser diagnostics but run only in verbose mode. Keep those paths in the

    // ordinary TELNET coverage lane while suppressing their high-volume text.

    // An explicit FUZZ_VERBOSE still skips the sink so reproductions remain

    // inspectable from the terminal.

    curl_easy_setopt(easy, CURLOPT_DEBUGFUNCTION, &SilentDebugCallback);

    curl_easy_setopt(easy, CURLOPT_VERBOSE, 1L);

  }

  // Each non-HTTP protocol must use its dedicated peer invariants. Keep them

  // out of the redirect allowlist so an HTTP response cannot switch a stream

  // mock into synchronous TELNET, two-channel FTP, or datagram TFTP semantics.

  // CURLOPT_PROTOCOLS_STR arrived in 7.85.0.

  const char* direct_protocols = kEventDrivenProtocolsAllowed;

  switch (scheme) {

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

      direct_protocols = kTelnetProtocolAllowed;

      break;

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

      direct_protocols = kFtpProtocolAllowed;

      break;

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

      direct_protocols = kTftpProtocolAllowed;

      break;

    case curl::fuzzer::proto::SCHEME_GOPHER:

      direct_protocols = "gopher";

      break;

    case curl::fuzzer::proto::SCHEME_GOPHERS:

      direct_protocols = "gophers";

      break;

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

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

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

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

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

    default:

      break;

  }

  curl_easy_setopt(easy, CURLOPT_PROTOCOLS_STR, direct_protocols);

  curl_easy_setopt(easy, CURLOPT_REDIR_PROTOCOLS_STR, kEventDrivenProtocolsAllowed);

  // CONNECT_TO confines direct connections, but an ambient http_proxy or

  // ALL_PROXY can select a proxy before curl asks the harness for a socket.

  // An explicit empty proxy keeps every transfer inside the socketpair and

  // makes replay independent of the machine running the fuzzer.

  curl_easy_setopt(easy, CURLOPT_PROXY, "");

  // Keep raw secure-scheme inputs independent of the host trust store,

  // matching the legacy harness. The dedicated TLS mock installs its own

  // in-memory trust anchor after this baseline; scenario options still run

  // last and can deliberately select verification failures.

  curl_easy_setopt(easy, CURLOPT_SSL_VERIFYPEER, 0L);

  // Force every name lookup to the fuzzer's in-process mock peer. The caller

  // owns the returned slist and must free it after curl_easy_cleanup.

  struct curl_slist* connect_to = curl_slist_append(nullptr, kConnectToOverride);

  curl_easy_setopt(easy, CURLOPT_CONNECT_TO, connect_to);

  // Short bounds: fuzzing should never sit waiting on real I/O. Response

  // volume is already bounded by libFuzzer's input-size limit, so do not rate

  // limit receive traffic here: a global bytes-per-second throttle turns every

  // otherwise-complete large response into wall-clock sleep.

  curl_easy_setopt(easy, CURLOPT_CONNECTTIMEOUT_MS, kConnectTimeoutMs);

  curl_easy_setopt(easy, CURLOPT_TIMEOUT_MS, kTimeoutMs);

  // Keep every persistence/read path deterministic and prevent scenarios from

  // leaking state onto the filesystem. COOKIEFILE also makes the in-memory

  // engine's RELOAD command traverse its loader against a harmless empty

  // source. These path options deliberately remain absent from the generated

  // mutation manifest, so a proto cannot replace /dev/null.

  curl_easy_setopt(easy, CURLOPT_COOKIEJAR, kDevNull);

  curl_easy_setopt(easy, CURLOPT_COOKIEFILE, kDevNull);

  curl_easy_setopt(easy, CURLOPT_ALTSVC, kDevNull);

  curl_easy_setopt(easy, CURLOPT_HSTS, kDevNull);

  curl_easy_setopt(easy, CURLOPT_NETRC_FILE, kDevNull);

  // Do not set CRLFILE merely to mirror the legacy harness. An empty CRL is

  // not a harmless sink: when a scenario restores certificate verification,

  // OpenSSL rejects /dev/null before it can exercise useful handshake and

  // verification paths. The option is absent from the mutation manifest, so

  // leaving it unset introduces neither filesystem writes nor external input.

  // Match the legacy TLV fuzzer: FUZZ_VERBOSE in the environment flips curl's

  // own verbose logging on. Useful when reproducing a crashing corpus entry.

  if (user_requested_verbose) {

    curl_easy_setopt(easy, CURLOPT_VERBOSE, 1L);

  }

  return connect_to;

}

/// Apply one SetOption to the easy handle. The Scenario passed to the runner

/// owns every SetOption for the whole transfer, so pointer-valued options can

/// borrow string_value directly instead of allocating a duplicate backing

/// store on every iteration. This lifetime is especially important for

/// CURLOPT_POSTFIELDS, which curl deliberately does not copy.

/// @param easy   The curl easy handle to configure.

/// @param option The SetOption proto describing which option and value to set;

///               its containing Scenario must remain stable through cleanup.

/// @return CURLE_OK on success, an error code if the option is unsupported or

///         the setopt call itself failed.

CURLcode ApplySetOption(CURL* easy, const curl::fuzzer::proto::SetOption& option) {

  const OptionDescriptor* desc = LookupOptionDescriptor(option.option_id());

  if (desc == nullptr) {

    return CURLE_UNKNOWN_OPTION;

  }

  switch (desc->kind) {

    case OptionValueKind::kString: {

      const std::string& value = option.string_value();

      // POSTFIELDS borrows its pointer and COPYPOSTFIELDS copies exactly the

      // previously configured size. Apply the correlated byte length first so

      // either option accepts embedded NULs without strlen semantics and the

      // copying variant can never read beyond the protobuf-owned buffer.

      if (desc->curlopt == CURLOPT_POSTFIELDS || desc->curlopt == CURLOPT_COPYPOSTFIELDS) {

        CURLcode result = curl_easy_setopt(easy, CURLOPT_POSTFIELDSIZE_LARGE, static_cast<curl_off_t>(value.size()));

        if (result != CURLE_OK) {

          return result;

        }

      }

      // Curl otherwise treats this option as a filename during the TLS

      // handshake. Fixed-policy inputs normally arrive pre-constrained by the

      // postprocessor; this runtime check also protects compatibility inputs,

      // which intentionally bypass it. Curl copies this option in setopt, so

      // the temporary remains valid for the call's full ownership contract.

      if (desc->curlopt == CURLOPT_PINNEDPUBLICKEY && !UsesInMemoryPublicKeyPin(value)) {

        std::string constrained = value;

        ConstrainPinnedPublicKeyValue(&constrained);

        return curl_easy_setopt(easy, desc->curlopt, constrained.c_str());

      }

      return curl_easy_setopt(easy, desc->curlopt, value.c_str());

    }

    // Decode the uint_value and pass it as either a long or a curl_off_t depending on the option.

    case OptionValueKind::kUint: {

      const std::uint64_t raw = DecodeIntegralValue(*desc, option);

      // CURLOPTTYPE_OFF_T options start at 30000. Everything below takes a

      // long; everything at/above takes a curl_off_t.

      if (static_cast<int>(desc->curlopt) >= 30000) {

        return curl_easy_setopt(easy, desc->curlopt, static_cast<curl_off_t>(raw));

      }

      return curl_easy_setopt(easy, desc->curlopt, static_cast<long>(raw));

    }

    // Decode the bool_value and pass it as a long flag (0 or 1).

    case OptionValueKind::kBool: {

      const long flag = static_cast<long>(DecodeIntegralValue(*desc, option));

      return curl_easy_setopt(easy, desc->curlopt, flag);

    }

  }

  return CURLE_UNKNOWN_OPTION;

}

/// Keep compatibility inputs immutable while enforcing the same observable

/// option prefix as postprocessed fixed lanes.

std::size_t RuntimeOptionCount(const curl::fuzzer::proto::Scenario& scenario) {

  return std::min<std::size_t>(static_cast<std::size_t>(scenario.options_size()), scenario_limits::kMaxOptions);

}

/// Apply only the prefix curl can observe in every target lane. Bounding here,

/// rather than relying solely on LPM's postprocessor, is important because

/// standalone compatibility seeds reach RunScenario without normalization.

std::size_t ApplyScenarioOptions(CURL* easy, const curl::fuzzer::proto::Scenario& scenario) {

  const std::size_t option_count = RuntimeOptionCount(scenario);

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

    (void)ApplySetOption(easy, scenario.options(static_cast<int>(index)));

  }

  return option_count;

}

}  // namespace proto_fuzzer