// Copyright (c) 2013 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 "net/quic/crypto/crypto_utils.h"

#include "crypto/hkdf.h"
#include "crypto/secure_hash.h"
#include "net/base/url_util.h"
#include "net/quic/crypto/crypto_handshake.h"
#include "net/quic/crypto/crypto_protocol.h"
#include "net/quic/crypto/quic_decrypter.h"
#include "net/quic/crypto/quic_encrypter.h"
#include "net/quic/crypto/quic_random.h"
#include "net/quic/quic_time.h"
#include "net/quic/quic_utils.h"
#include "url/url_canon.h"

using base::StringPiece;
using std::numeric_limits;
using std::string;

namespace net {

// static
void CryptoUtils::GenerateNonce(QuicWallTime now,
                                QuicRandom* random_generator,
                                StringPiece orbit,
                                string* nonce) {
  // a 4-byte timestamp + 28 random bytes.
  nonce->reserve(kNonceSize);
  nonce->resize(kNonceSize);

  uint32_t gmt_unix_time = static_cast<uint32_t>(now.ToUNIXSeconds());
  // The time in the nonce must be encoded in big-endian because the
  // strike-register depends on the nonces being ordered by time.
  (*nonce)[0] = static_cast<char>(gmt_unix_time >> 24);
  (*nonce)[1] = static_cast<char>(gmt_unix_time >> 16);
  (*nonce)[2] = static_cast<char>(gmt_unix_time >> 8);
  (*nonce)[3] = static_cast<char>(gmt_unix_time);
  size_t bytes_written = 4;

  if (orbit.size() == 8) {
    memcpy(&(*nonce)[bytes_written], orbit.data(), orbit.size());
    bytes_written += orbit.size();
  }

  random_generator->RandBytes(&(*nonce)[bytes_written],
                              kNonceSize - bytes_written);
}

// static
bool CryptoUtils::IsValidSNI(StringPiece sni) {
  // TODO(rtenneti): Support RFC2396 hostname.
  // NOTE: Microsoft does NOT enforce this spec, so if we throw away hostnames
  // based on the above spec, we may be losing some hostnames that windows
  // would consider valid. By far the most common hostname character NOT
  // accepted by the above spec is '_'.
  url::CanonHostInfo host_info;
  string canonicalized_host(CanonicalizeHost(sni.as_string(), &host_info));
  return !host_info.IsIPAddress() &&
         IsCanonicalizedHostCompliant(canonicalized_host) &&
         sni.find_last_of('.') != string::npos;
}

// static
string CryptoUtils::NormalizeHostname(const char* hostname) {
  url::CanonHostInfo host_info;
  string host(CanonicalizeHost(hostname, &host_info));

  // Walk backwards over the string, stopping at the first trailing dot.
  size_t host_end = host.length();
  while (host_end != 0 && host[host_end - 1] == '.') {
    host_end--;
  }

  // Erase the trailing dots.
  if (host_end != host.length()) {
    host.erase(host_end, host.length() - host_end);
  }
  return host;
}

// static
bool CryptoUtils::DeriveKeys(StringPiece premaster_secret,
                             QuicTag aead,
                             StringPiece client_nonce,
                             StringPiece server_nonce,
                             const string& hkdf_input,
                             Perspective perspective,
                             CrypterPair* crypters,
                             string* subkey_secret) {
  crypters->encrypter.reset(QuicEncrypter::Create(aead));
  crypters->decrypter.reset(QuicDecrypter::Create(aead));
  size_t key_bytes = crypters->encrypter->GetKeySize();
  size_t nonce_prefix_bytes = crypters->encrypter->GetNoncePrefixSize();
  size_t subkey_secret_bytes =
      subkey_secret == nullptr ? 0 : premaster_secret.length();

  StringPiece nonce = client_nonce;
  string nonce_storage;
  if (!server_nonce.empty()) {
    nonce_storage = client_nonce.as_string() + server_nonce.as_string();
    nonce = nonce_storage;
  }

  crypto::HKDF hkdf(premaster_secret, nonce, hkdf_input, key_bytes,
                    nonce_prefix_bytes, subkey_secret_bytes);
  if (perspective == Perspective::IS_SERVER) {
    if (!crypters->encrypter->SetKey(hkdf.server_write_key()) ||
        !crypters->encrypter->SetNoncePrefix(hkdf.server_write_iv()) ||
        !crypters->decrypter->SetKey(hkdf.client_write_key()) ||
        !crypters->decrypter->SetNoncePrefix(hkdf.client_write_iv())) {
      return false;
    }
  } else {
    if (!crypters->encrypter->SetKey(hkdf.client_write_key()) ||
        !crypters->encrypter->SetNoncePrefix(hkdf.client_write_iv()) ||
        !crypters->decrypter->SetKey(hkdf.server_write_key()) ||
        !crypters->decrypter->SetNoncePrefix(hkdf.server_write_iv())) {
      return false;
    }
  }
  if (subkey_secret != nullptr) {
    hkdf.subkey_secret().CopyToString(subkey_secret);
  }

  return true;
}

// static
bool CryptoUtils::ExportKeyingMaterial(StringPiece subkey_secret,
                                       StringPiece label,
                                       StringPiece context,
                                       size_t result_len,
                                       string* result) {
  for (size_t i = 0; i < label.length(); i++) {
    if (label[i] == '\0') {
      LOG(ERROR) << "ExportKeyingMaterial label may not contain NULs";
      return false;
    }
  }
  // Create HKDF info input: null-terminated label + length-prefixed context
  if (context.length() >= numeric_limits<uint32_t>::max()) {
    LOG(ERROR) << "Context value longer than 2^32";
    return false;
  }
  uint32_t context_length = static_cast<uint32_t>(context.length());
  string info = label.as_string();
  info.push_back('\0');
  info.append(reinterpret_cast<char*>(&context_length), sizeof(context_length));
  info.append(context.data(), context.length());

  crypto::HKDF hkdf(subkey_secret, StringPiece() /* no salt */, info,
                    result_len, 0 /* no fixed IV */, 0 /* no subkey secret */);
  hkdf.client_write_key().CopyToString(result);
  return true;
}

// static
uint64_t CryptoUtils::ComputeLeafCertHash(const std::string& cert) {
  return QuicUtils::FNV1a_64_Hash(cert.data(), cert.size());
}

QuicErrorCode CryptoUtils::ValidateServerHello(
    const CryptoHandshakeMessage& server_hello,
    const QuicVersionVector& negotiated_versions,
    string* error_details) {
  DCHECK(error_details != nullptr);

  if (server_hello.tag() != kSHLO) {
    *error_details = "Bad tag";
    return QUIC_INVALID_CRYPTO_MESSAGE_TYPE;
  }

  const QuicTag* supported_version_tags;
  size_t num_supported_versions;

  if (server_hello.GetTaglist(kVER, &supported_version_tags,
                              &num_supported_versions) != QUIC_NO_ERROR) {
    *error_details = "server hello missing version list";
    return QUIC_INVALID_CRYPTO_MESSAGE_PARAMETER;
  }
  if (!negotiated_versions.empty()) {
    bool mismatch = num_supported_versions != negotiated_versions.size();
    for (size_t i = 0; i < num_supported_versions && !mismatch; ++i) {
      mismatch = QuicTagToQuicVersion(supported_version_tags[i]) !=
                 negotiated_versions[i];
    }
    // The server sent a list of supported versions, and the connection
    // reports that there was a version negotiation during the handshake.
    // Ensure that these two lists are identical.
    if (mismatch) {
      *error_details = "Downgrade attack detected";
      return QUIC_VERSION_NEGOTIATION_MISMATCH;
    }
  }
  return QUIC_NO_ERROR;
}

QuicErrorCode CryptoUtils::ValidateClientHello(
    const CryptoHandshakeMessage& client_hello,
    QuicVersion version,
    const QuicVersionVector& supported_versions,
    string* error_details) {
  if (client_hello.tag() != kCHLO) {
    *error_details = "Bad tag";
    return QUIC_INVALID_CRYPTO_MESSAGE_TYPE;
  }

  // If the client's preferred version is not the version we are currently
  // speaking, then the client went through a version negotiation.  In this
  // case, we need to make sure that we actually do not support this version
  // and that it wasn't a downgrade attack.
  QuicTag client_version_tag;
  if (client_hello.GetUint32(kVER, &client_version_tag) != QUIC_NO_ERROR) {
    *error_details = "client hello missing version list";
    return QUIC_INVALID_CRYPTO_MESSAGE_PARAMETER;
  }
  QuicVersion client_version = QuicTagToQuicVersion(client_version_tag);
  if (client_version != version) {
    // Just because client_version is a valid version enum doesn't mean that
    // this server actually supports that version, so we check to see if
    // it's actually in the supported versions list.
    for (size_t i = 0; i < supported_versions.size(); ++i) {
      if (client_version == supported_versions[i]) {
        *error_details = "Downgrade attack detected";
        return QUIC_VERSION_NEGOTIATION_MISMATCH;
      }
    }
  }
  return QUIC_NO_ERROR;
}

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

// Returns the name of the HandshakeFailureReason as a char*
// static
const char* CryptoUtils::HandshakeFailureReasonToString(
    HandshakeFailureReason reason) {
  switch (reason) {
    RETURN_STRING_LITERAL(HANDSHAKE_OK);
    RETURN_STRING_LITERAL(CLIENT_NONCE_UNKNOWN_FAILURE);
    RETURN_STRING_LITERAL(CLIENT_NONCE_INVALID_FAILURE);
    RETURN_STRING_LITERAL(CLIENT_NONCE_NOT_UNIQUE_FAILURE);
    RETURN_STRING_LITERAL(CLIENT_NONCE_INVALID_ORBIT_FAILURE);
    RETURN_STRING_LITERAL(CLIENT_NONCE_INVALID_TIME_FAILURE);
    RETURN_STRING_LITERAL(CLIENT_NONCE_STRIKE_REGISTER_TIMEOUT);
    RETURN_STRING_LITERAL(CLIENT_NONCE_STRIKE_REGISTER_FAILURE);

    RETURN_STRING_LITERAL(SERVER_NONCE_DECRYPTION_FAILURE);
    RETURN_STRING_LITERAL(SERVER_NONCE_INVALID_FAILURE);
    RETURN_STRING_LITERAL(SERVER_NONCE_NOT_UNIQUE_FAILURE);
    RETURN_STRING_LITERAL(SERVER_NONCE_INVALID_TIME_FAILURE);
    RETURN_STRING_LITERAL(SERVER_NONCE_REQUIRED_FAILURE);

    RETURN_STRING_LITERAL(SERVER_CONFIG_INCHOATE_HELLO_FAILURE);
    RETURN_STRING_LITERAL(SERVER_CONFIG_UNKNOWN_CONFIG_FAILURE);

    RETURN_STRING_LITERAL(SOURCE_ADDRESS_TOKEN_INVALID_FAILURE);
    RETURN_STRING_LITERAL(SOURCE_ADDRESS_TOKEN_DECRYPTION_FAILURE);
    RETURN_STRING_LITERAL(SOURCE_ADDRESS_TOKEN_PARSE_FAILURE);
    RETURN_STRING_LITERAL(SOURCE_ADDRESS_TOKEN_DIFFERENT_IP_ADDRESS_FAILURE);
    RETURN_STRING_LITERAL(SOURCE_ADDRESS_TOKEN_CLOCK_SKEW_FAILURE);
    RETURN_STRING_LITERAL(SOURCE_ADDRESS_TOKEN_EXPIRED_FAILURE);

    RETURN_STRING_LITERAL(INVALID_EXPECTED_LEAF_CERTIFICATE);
    RETURN_STRING_LITERAL(MAX_FAILURE_REASON);
  }
  // Return a default value so that we return this when |reason| doesn't match
  // any HandshakeFailureReason.. This can happen when the message by the peer
  // (attacker) has invalid reason.
  return "INVALID_HANDSHAKE_FAILURE_REASON";
}

// static
void CryptoUtils::HashHandshakeMessage(const CryptoHandshakeMessage& message,
                                       string* output) {
  const QuicData& serialized = message.GetSerialized();
  scoped_ptr<crypto::SecureHash> hash(
      crypto::SecureHash::Create(crypto::SecureHash::SHA256));
  hash->Update(serialized.data(), serialized.length());
  uint8_t digest[32];
  hash->Finish(digest, sizeof(digest));
  output->assign(reinterpret_cast<const char*>(&digest), sizeof(digest));
}

}  // namespace net