// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "quic/test_tools/crypto_test_utils.h"

#include <algorithm>
#include <memory>
#include <string>
#include <utility>

#include "absl/strings/escaping.h"
#include "absl/strings/string_view.h"
#include "third_party/boringssl/src/include/openssl/bn.h"
#include "third_party/boringssl/src/include/openssl/ec.h"
#include "third_party/boringssl/src/include/openssl/ecdsa.h"
#include "third_party/boringssl/src/include/openssl/nid.h"
#include "third_party/boringssl/src/include/openssl/sha.h"
#include "quic/core/crypto/channel_id.h"
#include "quic/core/crypto/common_cert_set.h"
#include "quic/core/crypto/crypto_handshake.h"
#include "quic/core/crypto/quic_crypto_server_config.h"
#include "quic/core/crypto/quic_decrypter.h"
#include "quic/core/crypto/quic_encrypter.h"
#include "quic/core/crypto/quic_random.h"
#include "quic/core/proto/crypto_server_config_proto.h"
#include "quic/core/quic_clock.h"
#include "quic/core/quic_crypto_client_stream.h"
#include "quic/core/quic_crypto_server_stream_base.h"
#include "quic/core/quic_crypto_stream.h"
#include "quic/core/quic_server_id.h"
#include "quic/core/quic_utils.h"
#include "quic/core/quic_versions.h"
#include "quic/platform/api/quic_bug_tracker.h"
#include "quic/platform/api/quic_logging.h"
#include "quic/platform/api/quic_socket_address.h"
#include "quic/platform/api/quic_test.h"
#include "quic/test_tools/quic_connection_peer.h"
#include "quic/test_tools/quic_framer_peer.h"
#include "quic/test_tools/quic_stream_peer.h"
#include "quic/test_tools/quic_test_utils.h"
#include "quic/test_tools/simple_quic_framer.h"
#include "common/test_tools/quiche_test_utils.h"

namespace quic {
namespace test {

namespace crypto_test_utils {

namespace {

using testing::_;

// CryptoFramerVisitor is a framer visitor that records handshake messages.
class CryptoFramerVisitor : public CryptoFramerVisitorInterface {
 public:
  CryptoFramerVisitor() : error_(false) {}

  void OnError(CryptoFramer* /*framer*/) override { error_ = true; }

  void OnHandshakeMessage(const CryptoHandshakeMessage& message) override {
    messages_.push_back(message);
  }

  bool error() const { return error_; }

  const std::vector<CryptoHandshakeMessage>& messages() const {
    return messages_;
  }

 private:
  bool error_;
  std::vector<CryptoHandshakeMessage> messages_;
};

// HexChar parses |c| as a hex character. If valid, it sets |*value| to the
// value of the hex character and returns true. Otherwise it returns false.
bool HexChar(char c, uint8_t* value) {
  if (c >= '0' && c <= '9') {
    *value = c - '0';
    return true;
  }
  if (c >= 'a' && c <= 'f') {
    *value = c - 'a' + 10;
    return true;
  }
  if (c >= 'A' && c <= 'F') {
    *value = c - 'A' + 10;
    return true;
  }
  return false;
}

}  // anonymous namespace

FakeClientOptions::FakeClientOptions() {}

FakeClientOptions::~FakeClientOptions() {}

namespace {
// This class is used by GenerateFullCHLO() to extract SCID and STK from
// REJ and to construct a full CHLO with these fields and given inchoate
// CHLO.
class FullChloGenerator {
 public:
  FullChloGenerator(
      QuicCryptoServerConfig* crypto_config,
      QuicSocketAddress server_addr,
      QuicSocketAddress client_addr,
      const QuicClock* clock,
      ParsedQuicVersion version,
      QuicReferenceCountedPointer<QuicSignedServerConfig> signed_config,
      QuicCompressedCertsCache* compressed_certs_cache,
      CryptoHandshakeMessage* out)
      : crypto_config_(crypto_config),
        server_addr_(server_addr),
        client_addr_(client_addr),
        clock_(clock),
        version_(version),
        signed_config_(signed_config),
        compressed_certs_cache_(compressed_certs_cache),
        out_(out),
        params_(new QuicCryptoNegotiatedParameters) {}

  class ValidateClientHelloCallback : public ValidateClientHelloResultCallback {
   public:
    explicit ValidateClientHelloCallback(FullChloGenerator* generator)
        : generator_(generator) {}
    void Run(QuicReferenceCountedPointer<
                 ValidateClientHelloResultCallback::Result> result,
             std::unique_ptr<ProofSource::Details> /* details */) override {
      generator_->ValidateClientHelloDone(std::move(result));
    }

   private:
    FullChloGenerator* generator_;
  };

  std::unique_ptr<ValidateClientHelloCallback>
  GetValidateClientHelloCallback() {
    return std::make_unique<ValidateClientHelloCallback>(this);
  }

 private:
  void ValidateClientHelloDone(
      QuicReferenceCountedPointer<ValidateClientHelloResultCallback::Result>
          result) {
    result_ = result;
    crypto_config_->ProcessClientHello(
        result_, /*reject_only=*/false, TestConnectionId(1), server_addr_,
        client_addr_, version_, {version_}, clock_, QuicRandom::GetInstance(),
        compressed_certs_cache_, params_, signed_config_,
        /*total_framing_overhead=*/50, kDefaultMaxPacketSize,
        GetProcessClientHelloCallback());
  }

  class ProcessClientHelloCallback : public ProcessClientHelloResultCallback {
   public:
    explicit ProcessClientHelloCallback(FullChloGenerator* generator)
        : generator_(generator) {}
    void Run(QuicErrorCode error,
             const std::string& error_details,
             std::unique_ptr<CryptoHandshakeMessage> message,
             std::unique_ptr<DiversificationNonce> /*diversification_nonce*/,
             std::unique_ptr<ProofSource::Details> /*proof_source_details*/)
        override {
      ASSERT_TRUE(message) << QuicErrorCodeToString(error) << " "
                           << error_details;
      generator_->ProcessClientHelloDone(std::move(message));
    }

   private:
    FullChloGenerator* generator_;
  };

  std::unique_ptr<ProcessClientHelloCallback> GetProcessClientHelloCallback() {
    return std::make_unique<ProcessClientHelloCallback>(this);
  }

  void ProcessClientHelloDone(std::unique_ptr<CryptoHandshakeMessage> rej) {
    // Verify output is a REJ.
    EXPECT_THAT(rej->tag(), testing::Eq(kREJ));

    QUIC_VLOG(1) << "Extract valid STK and SCID from\n" << rej->DebugString();
    absl::string_view srct;
    ASSERT_TRUE(rej->GetStringPiece(kSourceAddressTokenTag, &srct));

    absl::string_view scfg;
    ASSERT_TRUE(rej->GetStringPiece(kSCFG, &scfg));
    std::unique_ptr<CryptoHandshakeMessage> server_config(
        CryptoFramer::ParseMessage(scfg));

    absl::string_view scid;
    ASSERT_TRUE(server_config->GetStringPiece(kSCID, &scid));

    *out_ = result_->client_hello;
    out_->SetStringPiece(kSCID, scid);
    out_->SetStringPiece(kSourceAddressTokenTag, srct);
    uint64_t xlct = LeafCertHashForTesting();
    out_->SetValue(kXLCT, xlct);
  }

 protected:
  QuicCryptoServerConfig* crypto_config_;
  QuicSocketAddress server_addr_;
  QuicSocketAddress client_addr_;
  const QuicClock* clock_;
  ParsedQuicVersion version_;
  QuicReferenceCountedPointer<QuicSignedServerConfig> signed_config_;
  QuicCompressedCertsCache* compressed_certs_cache_;
  CryptoHandshakeMessage* out_;

  QuicReferenceCountedPointer<QuicCryptoNegotiatedParameters> params_;
  QuicReferenceCountedPointer<ValidateClientHelloResultCallback::Result>
      result_;
};

}  // namespace

std::unique_ptr<QuicCryptoServerConfig> CryptoServerConfigForTesting() {
  return std::make_unique<QuicCryptoServerConfig>(
      QuicCryptoServerConfig::TESTING, QuicRandom::GetInstance(),
      ProofSourceForTesting(), KeyExchangeSource::Default());
}

int HandshakeWithFakeServer(QuicConfig* server_quic_config,
                            QuicCryptoServerConfig* crypto_config,
                            MockQuicConnectionHelper* helper,
                            MockAlarmFactory* alarm_factory,
                            PacketSavingConnection* client_conn,
                            QuicCryptoClientStream* client,
                            std::string alpn) {
  auto* server_conn = new testing::NiceMock<PacketSavingConnection>(
      helper, alarm_factory, Perspective::IS_SERVER,
      ParsedVersionOfIndex(client_conn->supported_versions(), 0));

  QuicCompressedCertsCache compressed_certs_cache(
      QuicCompressedCertsCache::kQuicCompressedCertsCacheSize);
  SetupCryptoServerConfigForTest(
      server_conn->clock(), server_conn->random_generator(), crypto_config);

  TestQuicSpdyServerSession server_session(
      server_conn, *server_quic_config, client_conn->supported_versions(),
      crypto_config, &compressed_certs_cache);
  // Call SetServerApplicationStateForResumption so that the fake server
  // supports 0-RTT in TLS.
  server_session.Initialize();
  server_session.GetMutableCryptoStream()
      ->SetServerApplicationStateForResumption(
          std::make_unique<ApplicationState>());
  EXPECT_CALL(*server_session.helper(),
              CanAcceptClientHello(testing::_, testing::_, testing::_,
                                   testing::_, testing::_))
      .Times(testing::AnyNumber());
  EXPECT_CALL(*server_conn, OnCanWrite()).Times(testing::AnyNumber());
  EXPECT_CALL(*client_conn, OnCanWrite()).Times(testing::AnyNumber());
  EXPECT_CALL(*server_conn, SendCryptoData(_, _, _))
      .Times(testing::AnyNumber());
  EXPECT_CALL(server_session, SelectAlpn(_))
      .WillRepeatedly([alpn](const std::vector<absl::string_view>& alpns) {
        return std::find(alpns.cbegin(), alpns.cend(), alpn);
      });

  // The client's handshake must have been started already.
  QUICHE_CHECK_NE(0u, client_conn->encrypted_packets_.size());

  CommunicateHandshakeMessages(client_conn, client, server_conn,
                               server_session.GetMutableCryptoStream());
  if (client_conn->connected() && server_conn->connected()) {
    CompareClientAndServerKeys(client, server_session.GetMutableCryptoStream());
  }

  return client->num_sent_client_hellos();
}

int HandshakeWithFakeClient(MockQuicConnectionHelper* helper,
                            MockAlarmFactory* alarm_factory,
                            PacketSavingConnection* server_conn,
                            QuicCryptoServerStreamBase* server,
                            const QuicServerId& server_id,
                            const FakeClientOptions& options,
                            std::string alpn) {
  // This function does not do version negotiation; read the supported versions
  // directly from the server connection instead.
  ParsedQuicVersionVector supported_versions =
      server_conn->supported_versions();
  if (options.only_tls_versions) {
    supported_versions.erase(
        std::remove_if(supported_versions.begin(), supported_versions.end(),
                       [](const ParsedQuicVersion& version) {
                         return version.handshake_protocol != PROTOCOL_TLS1_3;
                       }),
        supported_versions.end());
    QUICHE_CHECK(!options.only_quic_crypto_versions);
  } else if (options.only_quic_crypto_versions) {
    supported_versions.erase(
        std::remove_if(supported_versions.begin(), supported_versions.end(),
                       [](const ParsedQuicVersion& version) {
                         return version.handshake_protocol !=
                                PROTOCOL_QUIC_CRYPTO;
                       }),
        supported_versions.end());
  }
  PacketSavingConnection* client_conn = new PacketSavingConnection(
      helper, alarm_factory, Perspective::IS_CLIENT, supported_versions);
  // Advance the time, because timers do not like uninitialized times.
  client_conn->AdvanceTime(QuicTime::Delta::FromSeconds(1));

  QuicCryptoClientConfig crypto_config(ProofVerifierForTesting());
  TestQuicSpdyClientSession client_session(client_conn, DefaultQuicConfig(),
                                           supported_versions, server_id,
                                           &crypto_config);

  EXPECT_CALL(client_session, OnProofValid(testing::_))
      .Times(testing::AnyNumber());
  EXPECT_CALL(client_session, OnProofVerifyDetailsAvailable(testing::_))
      .Times(testing::AnyNumber());
  EXPECT_CALL(*client_conn, OnCanWrite()).Times(testing::AnyNumber());
  if (!alpn.empty()) {
    EXPECT_CALL(client_session, GetAlpnsToOffer())
        .WillRepeatedly(testing::Return(std::vector<std::string>({alpn})));
  } else {
    EXPECT_CALL(client_session, GetAlpnsToOffer())
        .WillRepeatedly(testing::Return(std::vector<std::string>(
            {AlpnForVersion(client_conn->version())})));
  }
  client_session.GetMutableCryptoStream()->CryptoConnect();
  QUICHE_CHECK_EQ(1u, client_conn->encrypted_packets_.size());

  CommunicateHandshakeMessages(client_conn,
                               client_session.GetMutableCryptoStream(),
                               server_conn, server);

  if (server->one_rtt_keys_available() && server->encryption_established()) {
    CompareClientAndServerKeys(client_session.GetMutableCryptoStream(), server);
  }

  return client_session.GetCryptoStream()->num_sent_client_hellos();
}

void SetupCryptoServerConfigForTest(const QuicClock* clock,
                                    QuicRandom* rand,
                                    QuicCryptoServerConfig* crypto_config) {
  QuicCryptoServerConfig::ConfigOptions options;
  options.channel_id_enabled = true;
  std::unique_ptr<CryptoHandshakeMessage> scfg =
      crypto_config->AddDefaultConfig(rand, clock, options);
}

void SendHandshakeMessageToStream(QuicCryptoStream* stream,
                                  const CryptoHandshakeMessage& message,
                                  Perspective /*perspective*/) {
  const QuicData& data = message.GetSerialized();
  QuicSession* session = QuicStreamPeer::session(stream);
  if (!QuicVersionUsesCryptoFrames(session->transport_version())) {
    QuicStreamFrame frame(
        QuicUtils::GetCryptoStreamId(session->transport_version()), false,
        stream->crypto_bytes_read(), data.AsStringPiece());
    stream->OnStreamFrame(frame);
  } else {
    EncryptionLevel level = session->connection()->last_decrypted_level();
    QuicCryptoFrame frame(level, stream->BytesReadOnLevel(level),
                          data.AsStringPiece());
    stream->OnCryptoFrame(frame);
  }
}

void CommunicateHandshakeMessages(PacketSavingConnection* client_conn,
                                  QuicCryptoStream* client,
                                  PacketSavingConnection* server_conn,
                                  QuicCryptoStream* server) {
  size_t client_i = 0, server_i = 0;
  while (client_conn->connected() && server_conn->connected() &&
         (!client->one_rtt_keys_available() ||
          !server->one_rtt_keys_available())) {
    ASSERT_GT(client_conn->encrypted_packets_.size(), client_i);
    QUIC_LOG(INFO) << "Processing "
                   << client_conn->encrypted_packets_.size() - client_i
                   << " packets client->server";
    MovePackets(client_conn, &client_i, server, server_conn,
                Perspective::IS_SERVER);

    if (client->one_rtt_keys_available() && server->one_rtt_keys_available() &&
        server_conn->encrypted_packets_.size() == server_i) {
      break;
    }
    ASSERT_GT(server_conn->encrypted_packets_.size(), server_i);
    QUIC_LOG(INFO) << "Processing "
                   << server_conn->encrypted_packets_.size() - server_i
                   << " packets server->client";
    MovePackets(server_conn, &server_i, client, client_conn,
                Perspective::IS_CLIENT);
  }
}

std::pair<size_t, size_t> AdvanceHandshake(PacketSavingConnection* client_conn,
                                           QuicCryptoStream* client,
                                           size_t client_i,
                                           PacketSavingConnection* server_conn,
                                           QuicCryptoStream* server,
                                           size_t server_i) {
  if (client_conn->encrypted_packets_.size() != client_i) {
    QUIC_LOG(INFO) << "Processing "
                   << client_conn->encrypted_packets_.size() - client_i
                   << " packets client->server";
    MovePackets(client_conn, &client_i, server, server_conn,
                Perspective::IS_SERVER);
  }

  if (server_conn->encrypted_packets_.size() != server_i) {
    QUIC_LOG(INFO) << "Processing "
                   << server_conn->encrypted_packets_.size() - server_i
                   << " packets server->client";
    MovePackets(server_conn, &server_i, client, client_conn,
                Perspective::IS_CLIENT);
  }

  return std::make_pair(client_i, server_i);
}

std::string GetValueForTag(const CryptoHandshakeMessage& message, QuicTag tag) {
  auto it = message.tag_value_map().find(tag);
  if (it == message.tag_value_map().end()) {
    return std::string();
  }
  return it->second;
}

uint64_t LeafCertHashForTesting() {
  QuicReferenceCountedPointer<ProofSource::Chain> chain;
  QuicSocketAddress server_address(QuicIpAddress::Any4(), 42);
  QuicSocketAddress client_address(QuicIpAddress::Any4(), 43);
  QuicCryptoProof proof;
  std::unique_ptr<ProofSource> proof_source(ProofSourceForTesting());

  class Callback : public ProofSource::Callback {
   public:
    Callback(bool* ok, QuicReferenceCountedPointer<ProofSource::Chain>* chain)
        : ok_(ok), chain_(chain) {}

    void Run(bool ok,
             const QuicReferenceCountedPointer<ProofSource::Chain>& chain,
             const QuicCryptoProof& /* proof */,
             std::unique_ptr<ProofSource::Details> /* details */) override {
      *ok_ = ok;
      *chain_ = chain;
    }

   private:
    bool* ok_;
    QuicReferenceCountedPointer<ProofSource::Chain>* chain_;
  };

  // Note: relies on the callback being invoked synchronously
  bool ok = false;
  proof_source->GetProof(
      server_address, client_address, "", "",
      AllSupportedVersionsWithQuicCrypto().front().transport_version, "",
      std::unique_ptr<ProofSource::Callback>(new Callback(&ok, &chain)));
  if (!ok || chain->certs.empty()) {
    QUICHE_DCHECK(false) << "Proof generation failed";
    return 0;
  }

  return QuicUtils::FNV1a_64_Hash(chain->certs.at(0));
}

class MockCommonCertSets : public CommonCertSets {
 public:
  MockCommonCertSets(absl::string_view cert, uint64_t hash, uint32_t index)
      : cert_(cert), hash_(hash), index_(index) {}

  absl::string_view GetCommonHashes() const override {
    QUIC_BUG(quic_bug_10142_1) << "not implemented";
    return absl::string_view();
  }

  absl::string_view GetCert(uint64_t hash, uint32_t index) const override {
    if (hash == hash_ && index == index_) {
      return cert_;
    }
    return absl::string_view();
  }

  bool MatchCert(absl::string_view cert,
                 absl::string_view common_set_hashes,
                 uint64_t* out_hash,
                 uint32_t* out_index) const override {
    if (cert != cert_) {
      return false;
    }

    if (common_set_hashes.size() % sizeof(uint64_t) != 0) {
      return false;
    }
    bool client_has_set = false;
    for (size_t i = 0; i < common_set_hashes.size(); i += sizeof(uint64_t)) {
      uint64_t hash;
      memcpy(&hash, common_set_hashes.data() + i, sizeof(hash));
      if (hash == hash_) {
        client_has_set = true;
        break;
      }
    }

    if (!client_has_set) {
      return false;
    }

    *out_hash = hash_;
    *out_index = index_;
    return true;
  }

 private:
  const std::string cert_;
  const uint64_t hash_;
  const uint32_t index_;
};

CommonCertSets* MockCommonCertSets(absl::string_view cert,
                                   uint64_t hash,
                                   uint32_t index) {
  return new class MockCommonCertSets(cert, hash, index);
}

void FillInDummyReject(CryptoHandshakeMessage* rej) {
  rej->set_tag(kREJ);

  // Minimum SCFG that passes config validation checks.
  // clang-format off
  unsigned char scfg[] = {
    // SCFG
    0x53, 0x43, 0x46, 0x47,
    // num entries
    0x01, 0x00,
    // padding
    0x00, 0x00,
    // EXPY
    0x45, 0x58, 0x50, 0x59,
    // EXPY end offset
    0x08, 0x00, 0x00, 0x00,
    // Value
    '1',  '2',  '3',  '4',
    '5',  '6',  '7',  '8'
  };
  // clang-format on
  rej->SetValue(kSCFG, scfg);
  rej->SetStringPiece(kServerNonceTag, "SERVER_NONCE");
  int64_t ttl = 2 * 24 * 60 * 60;
  rej->SetValue(kSTTL, ttl);
  std::vector<QuicTag> reject_reasons;
  reject_reasons.push_back(CLIENT_NONCE_INVALID_FAILURE);
  rej->SetVector(kRREJ, reject_reasons);
}

namespace {

#define RETURN_STRING_LITERAL(x) \
  case x:                        \
    return #x

std::string EncryptionLevelString(EncryptionLevel level) {
  switch (level) {
    RETURN_STRING_LITERAL(ENCRYPTION_INITIAL);
    RETURN_STRING_LITERAL(ENCRYPTION_HANDSHAKE);
    RETURN_STRING_LITERAL(ENCRYPTION_ZERO_RTT);
    RETURN_STRING_LITERAL(ENCRYPTION_FORWARD_SECURE);
    default:
      return "";
  }
}

void CompareCrypters(const QuicEncrypter* encrypter,
                     const QuicDecrypter* decrypter,
                     std::string label) {
  if (encrypter == nullptr || decrypter == nullptr) {
    ADD_FAILURE() << "Expected non-null crypters; have " << encrypter << " and "
                  << decrypter << " for " << label;
    return;
  }
  absl::string_view encrypter_key = encrypter->GetKey();
  absl::string_view encrypter_iv = encrypter->GetNoncePrefix();
  absl::string_view decrypter_key = decrypter->GetKey();
  absl::string_view decrypter_iv = decrypter->GetNoncePrefix();
  quiche::test::CompareCharArraysWithHexError(
      label + " key", encrypter_key.data(), encrypter_key.length(),
      decrypter_key.data(), decrypter_key.length());
  quiche::test::CompareCharArraysWithHexError(
      label + " iv", encrypter_iv.data(), encrypter_iv.length(),
      decrypter_iv.data(), decrypter_iv.length());
}

}  // namespace

void CompareClientAndServerKeys(QuicCryptoClientStream* client,
                                QuicCryptoServerStreamBase* server) {
  QuicFramer* client_framer = QuicConnectionPeer::GetFramer(
      QuicStreamPeer::session(client)->connection());
  QuicFramer* server_framer = QuicConnectionPeer::GetFramer(
      QuicStreamPeer::session(server)->connection());
  for (EncryptionLevel level :
       {ENCRYPTION_HANDSHAKE, ENCRYPTION_ZERO_RTT, ENCRYPTION_FORWARD_SECURE}) {
    SCOPED_TRACE(EncryptionLevelString(level));
    const QuicEncrypter* client_encrypter(
        QuicFramerPeer::GetEncrypter(client_framer, level));
    const QuicDecrypter* server_decrypter(
        QuicFramerPeer::GetDecrypter(server_framer, level));
    if (level == ENCRYPTION_FORWARD_SECURE ||
        !((level == ENCRYPTION_HANDSHAKE || level == ENCRYPTION_ZERO_RTT ||
           client_encrypter == nullptr) &&
          (level == ENCRYPTION_ZERO_RTT || server_decrypter == nullptr))) {
      CompareCrypters(client_encrypter, server_decrypter,
                      "client " + EncryptionLevelString(level) + " write");
    }
    const QuicEncrypter* server_encrypter(
        QuicFramerPeer::GetEncrypter(server_framer, level));
    const QuicDecrypter* client_decrypter(
        QuicFramerPeer::GetDecrypter(client_framer, level));
    if (level == ENCRYPTION_FORWARD_SECURE ||
        !(server_encrypter == nullptr &&
          (level == ENCRYPTION_HANDSHAKE || level == ENCRYPTION_ZERO_RTT ||
           client_decrypter == nullptr))) {
      CompareCrypters(server_encrypter, client_decrypter,
                      "server " + EncryptionLevelString(level) + " write");
    }
  }

  absl::string_view client_subkey_secret =
      client->crypto_negotiated_params().subkey_secret;
  absl::string_view server_subkey_secret =
      server->crypto_negotiated_params().subkey_secret;
  quiche::test::CompareCharArraysWithHexError(
      "subkey secret", client_subkey_secret.data(),
      client_subkey_secret.length(), server_subkey_secret.data(),
      server_subkey_secret.length());
}

QuicTag ParseTag(const char* tagstr) {
  const size_t len = strlen(tagstr);
  QUICHE_CHECK_NE(0u, len);

  QuicTag tag = 0;

  if (tagstr[0] == '#') {
    QUICHE_CHECK_EQ(static_cast<size_t>(1 + 2 * 4), len);
    tagstr++;

    for (size_t i = 0; i < 8; i++) {
      tag <<= 4;

      uint8_t v = 0;
      QUICHE_CHECK(HexChar(tagstr[i], &v));
      tag |= v;
    }

    return tag;
  }

  QUICHE_CHECK_LE(len, 4u);
  for (size_t i = 0; i < 4; i++) {
    tag >>= 8;
    if (i < len) {
      tag |= static_cast<uint32_t>(tagstr[i]) << 24;
    }
  }

  return tag;
}

CryptoHandshakeMessage CreateCHLO(
    std::vector<std::pair<std::string, std::string>> tags_and_values) {
  return CreateCHLO(tags_and_values, -1);
}

CryptoHandshakeMessage CreateCHLO(
    std::vector<std::pair<std::string, std::string>> tags_and_values,
    int minimum_size_bytes) {
  CryptoHandshakeMessage msg;
  msg.set_tag(MakeQuicTag('C', 'H', 'L', 'O'));

  if (minimum_size_bytes > 0) {
    msg.set_minimum_size(minimum_size_bytes);
  }

  for (const auto& tag_and_value : tags_and_values) {
    const std::string& tag = tag_and_value.first;
    const std::string& value = tag_and_value.second;

    const QuicTag quic_tag = ParseTag(tag.c_str());

    size_t value_len = value.length();
    if (value_len > 0 && value[0] == '#') {
      // This is ascii encoded hex.
      std::string hex_value =
          absl::HexStringToBytes(absl::string_view(&value[1]));
      msg.SetStringPiece(quic_tag, hex_value);
      continue;
    }
    msg.SetStringPiece(quic_tag, value);
  }

  // The CryptoHandshakeMessage needs to be serialized and parsed to ensure
  // that any padding is included.
  std::unique_ptr<QuicData> bytes =
      CryptoFramer::ConstructHandshakeMessage(msg);
  std::unique_ptr<CryptoHandshakeMessage> parsed(
      CryptoFramer::ParseMessage(bytes->AsStringPiece()));
  QUICHE_CHECK(parsed);

  return *parsed;
}

void MovePackets(PacketSavingConnection* source_conn,
                 size_t* inout_packet_index,
                 QuicCryptoStream* dest_stream,
                 PacketSavingConnection* dest_conn,
                 Perspective dest_perspective) {
  SimpleQuicFramer framer(source_conn->supported_versions(), dest_perspective);
  QuicFramerPeer::SetLastSerializedServerConnectionId(framer.framer(),
                                                      TestConnectionId());

  SimpleQuicFramer null_encryption_framer(source_conn->supported_versions(),
                                          dest_perspective);
  QuicFramerPeer::SetLastSerializedServerConnectionId(
      null_encryption_framer.framer(), TestConnectionId());

  size_t index = *inout_packet_index;
  for (; index < source_conn->encrypted_packets_.size(); index++) {
    if (!dest_conn->connected()) {
      QUIC_LOG(INFO)
          << "Destination connection disconnected. Skipping packet at index "
          << index;
      continue;
    }
    // In order to properly test the code we need to perform encryption and
    // decryption so that the crypters latch when expected. The crypters are in
    // |dest_conn|, but we don't want to try and use them there. Instead we swap
    // them into |framer|, perform the decryption with them, and then swap ther
    // back.
    QuicConnectionPeer::SwapCrypters(dest_conn, framer.framer());
    QuicConnectionPeer::AddBytesReceived(
        dest_conn, source_conn->encrypted_packets_[index]->length());
    if (!framer.ProcessPacket(*source_conn->encrypted_packets_[index])) {
      // The framer will be unable to decrypt zero-rtt packets sent during
      // handshake or forward-secure packets sent after the handshake is
      // complete. Don't treat them as handshake packets.
      QuicConnectionPeer::SwapCrypters(dest_conn, framer.framer());
      continue;
    }
    QuicConnectionPeer::SwapCrypters(dest_conn, framer.framer());

    // Install a packet flusher such that the packets generated by |dest_conn|
    // in response to this packet are more likely to be coalesced and/or batched
    // in the writer.
    QuicConnection::ScopedPacketFlusher flusher(dest_conn);

    dest_conn->OnDecryptedPacket(
        source_conn->encrypted_packets_[index]->length(),
        framer.last_decrypted_level());

    if (dest_stream->handshake_protocol() == PROTOCOL_TLS1_3) {
      // Try to process the packet with a framer that only has the NullDecrypter
      // for decryption. If ProcessPacket succeeds, that means the packet was
      // encrypted with the NullEncrypter. With the TLS handshaker in use, no
      // packets should ever be encrypted with the NullEncrypter, instead
      // they're encrypted with an obfuscation cipher based on QUIC version and
      // connection ID.
      QUIC_LOG(INFO) << "Attempting to decrypt with NullDecrypter: "
                        "expect a decryption failure on the next log line.";
      ASSERT_FALSE(null_encryption_framer.ProcessPacket(
          *source_conn->encrypted_packets_[index]))
          << "No TLS packets should be encrypted with the NullEncrypter";
    }

    // Since we're using QuicFramers separate from the connections to move
    // packets, the QuicConnection never gets notified about what level the last
    // packet was decrypted at. This is needed by TLS to know what encryption
    // level was used for the data it's receiving, so we plumb this information
    // from the SimpleQuicFramer back into the connection.
    dest_conn->OnDecryptedPacket(
        source_conn->encrypted_packets_[index]->length(),
        framer.last_decrypted_level());

    QuicConnectionPeer::SetCurrentPacket(
        dest_conn, source_conn->encrypted_packets_[index]->AsStringPiece());
    for (const auto& stream_frame : framer.stream_frames()) {
      // Ignore stream frames that are sent on other streams in the crypto
      // event.
      if (stream_frame->stream_id == dest_stream->id()) {
        dest_stream->OnStreamFrame(*stream_frame);
      }
    }
    for (const auto& crypto_frame : framer.crypto_frames()) {
      dest_stream->OnCryptoFrame(*crypto_frame);
    }
    if (!framer.connection_close_frames().empty() && dest_conn->connected()) {
      dest_conn->OnConnectionCloseFrame(framer.connection_close_frames()[0]);
    }
  }
  *inout_packet_index = index;

  QuicConnectionPeer::SetCurrentPacket(dest_conn,
                                       absl::string_view(nullptr, 0));
}

CryptoHandshakeMessage GenerateDefaultInchoateCHLO(
    const QuicClock* clock,
    QuicTransportVersion version,
    QuicCryptoServerConfig* crypto_config) {
  // clang-format off
  return CreateCHLO(
      {{"PDMD", "X509"},
       {"AEAD", "AESG"},
       {"KEXS", "C255"},
       {"PUBS", GenerateClientPublicValuesHex().c_str()},
       {"NONC", GenerateClientNonceHex(clock, crypto_config).c_str()},
       {"VER\0", QuicVersionLabelToString(
           CreateQuicVersionLabel(
            ParsedQuicVersion(PROTOCOL_QUIC_CRYPTO, version))).c_str()}},
      kClientHelloMinimumSize);
  // clang-format on
}

std::string GenerateClientNonceHex(const QuicClock* clock,
                                   QuicCryptoServerConfig* crypto_config) {
  QuicCryptoServerConfig::ConfigOptions old_config_options;
  QuicCryptoServerConfig::ConfigOptions new_config_options;
  old_config_options.id = "old-config-id";
  crypto_config->AddDefaultConfig(QuicRandom::GetInstance(), clock,
                                  old_config_options);
  QuicServerConfigProtobuf primary_config = crypto_config->GenerateConfig(
      QuicRandom::GetInstance(), clock, new_config_options);
  primary_config.set_primary_time(clock->WallNow().ToUNIXSeconds());
  std::unique_ptr<CryptoHandshakeMessage> msg =
      crypto_config->AddConfig(primary_config, clock->WallNow());
  absl::string_view orbit;
  QUICHE_CHECK(msg->GetStringPiece(kORBT, &orbit));
  std::string nonce;
  CryptoUtils::GenerateNonce(clock->WallNow(), QuicRandom::GetInstance(), orbit,
                             &nonce);
  return ("#" + absl::BytesToHexString(nonce));
}

std::string GenerateClientPublicValuesHex() {
  char public_value[32];
  memset(public_value, 42, sizeof(public_value));
  return ("#" + absl::BytesToHexString(
                    absl::string_view(public_value, sizeof(public_value))));
}

void GenerateFullCHLO(
    const CryptoHandshakeMessage& inchoate_chlo,
    QuicCryptoServerConfig* crypto_config,
    QuicSocketAddress server_addr,
    QuicSocketAddress client_addr,
    QuicTransportVersion transport_version,
    const QuicClock* clock,
    QuicReferenceCountedPointer<QuicSignedServerConfig> signed_config,
    QuicCompressedCertsCache* compressed_certs_cache,
    CryptoHandshakeMessage* out) {
  // Pass a inchoate CHLO.
  FullChloGenerator generator(
      crypto_config, server_addr, client_addr, clock,
      ParsedQuicVersion(PROTOCOL_QUIC_CRYPTO, transport_version), signed_config,
      compressed_certs_cache, out);
  crypto_config->ValidateClientHello(
      inchoate_chlo, client_addr, server_addr, transport_version, clock,
      signed_config, generator.GetValidateClientHelloCallback());
}

}  // namespace crypto_test_utils
}  // namespace test
}  // namespace quic