// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/cert/ct_serialization.h"

#include <string>
#include <string_view>

#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "net/base/test_completion_callback.h"
#include "net/cert/merkle_tree_leaf.h"
#include "net/cert/signed_certificate_timestamp.h"
#include "net/cert/signed_tree_head.h"
#include "net/cert/x509_certificate.h"
#include "net/test/cert_test_util.h"
#include "net/test/ct_test_util.h"
#include "net/test/test_data_directory.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

using ::testing::ElementsAreArray;

namespace net {

class CtSerializationTest : public ::testing::Test {
 public:
  void SetUp() override {
    test_digitally_signed_ = ct::GetTestDigitallySigned();
  }

 protected:
  std::string test_digitally_signed_;
};

TEST_F(CtSerializationTest, DecodesDigitallySigned) {
  std::string_view digitally_signed(test_digitally_signed_);
  ct::DigitallySigned parsed;

  ASSERT_TRUE(ct::DecodeDigitallySigned(&digitally_signed, &parsed));
  EXPECT_EQ(
      ct::DigitallySigned::HASH_ALGO_SHA256,
      parsed.hash_algorithm);

  EXPECT_EQ(
      ct::DigitallySigned::SIG_ALGO_ECDSA,
      parsed.signature_algorithm);

  // The encoded data contains the signature itself from the 4th byte.
  // The first bytes are:
  // 1 byte of hash algorithm
  // 1 byte of signature algorithm
  // 2 bytes - prefix containing length of the signature data.
  EXPECT_EQ(
      test_digitally_signed_.substr(4),
      parsed.signature_data);
}


TEST_F(CtSerializationTest, FailsToDecodePartialDigitallySigned) {
  std::string_view digitally_signed(test_digitally_signed_);
  std::string_view partial_digitally_signed(
      digitally_signed.substr(0, test_digitally_signed_.size() - 5));
  ct::DigitallySigned parsed;

  ASSERT_FALSE(ct::DecodeDigitallySigned(&partial_digitally_signed, &parsed));
}


TEST_F(CtSerializationTest, EncodesDigitallySigned) {
  ct::DigitallySigned digitally_signed;
  digitally_signed.hash_algorithm = ct::DigitallySigned::HASH_ALGO_SHA256;
  digitally_signed.signature_algorithm = ct::DigitallySigned::SIG_ALGO_ECDSA;
  digitally_signed.signature_data = test_digitally_signed_.substr(4);

  std::string encoded;

  ASSERT_TRUE(ct::EncodeDigitallySigned(digitally_signed, &encoded));
  EXPECT_EQ(test_digitally_signed_, encoded);
}

TEST_F(CtSerializationTest, EncodesSignedEntryForX509Cert) {
  ct::SignedEntryData entry;
  ct::GetX509CertSignedEntry(&entry);

  std::string encoded;
  ASSERT_TRUE(ct::EncodeSignedEntry(entry, &encoded));
  EXPECT_EQ((718U + 5U), encoded.size());
  // First two bytes are log entry type. Next, length:
  // Length is 718 which is 512 + 206, which is 0x2ce
  std::string expected_prefix("\0\0\0\x2\xCE", 5);
  // Note we use std::string comparison rather than ASSERT_STREQ due
  // to null characters in the buffer.
  EXPECT_EQ(expected_prefix, encoded.substr(0, 5));
}

TEST_F(CtSerializationTest, EncodesSignedEntryForPrecert) {
  ct::SignedEntryData entry;
  ct::GetPrecertSignedEntry(&entry);

  std::string encoded;
  ASSERT_TRUE(ct::EncodeSignedEntry(entry, &encoded));
  EXPECT_EQ(604u, encoded.size());
  // First two bytes are the log entry type.
  EXPECT_EQ(std::string("\x00\x01", 2), encoded.substr(0, 2));
  // Next comes the 32-byte issuer key hash
  EXPECT_THAT(encoded.substr(2, 32), ElementsAreArray(entry.issuer_key_hash));
  // Then the length of the TBS cert (604 bytes = 0x237)
  EXPECT_EQ(std::string("\x00\x02\x37", 3), encoded.substr(34, 3));
  // Then the TBS cert itself
  EXPECT_EQ(entry.tbs_certificate, encoded.substr(37));
}

TEST_F(CtSerializationTest, EncodesV1SCTSignedData) {
  base::Time timestamp =
      base::Time::UnixEpoch() + base::Milliseconds(1348589665525);
  std::string dummy_entry("abc");
  std::string empty_extensions;
  // For now, no known failure cases.
  std::string encoded;
  ASSERT_TRUE(ct::EncodeV1SCTSignedData(
      timestamp,
      dummy_entry,
      empty_extensions,
      &encoded));
  EXPECT_EQ((size_t) 15, encoded.size());
  // Byte 0 is version, byte 1 is signature type
  // Bytes 2-10 are timestamp
  // Bytes 11-14 are the log signature
  // Byte 15 is the empty extension
  //EXPECT_EQ(0, timestamp.ToTimeT());
  std::string expected_buffer(
      "\x0\x0\x0\x0\x1\x39\xFE\x35\x3C\xF5\x61\x62\x63\x0\x0", 15);
  EXPECT_EQ(expected_buffer, encoded);
}

TEST_F(CtSerializationTest, DecodesSCTList) {
  // Two items in the list: "abc", "def"
  std::string_view encoded("\x0\xa\x0\x3\x61\x62\x63\x0\x3\x64\x65\x66", 12);
  std::vector<std::string_view> decoded;

  ASSERT_TRUE(ct::DecodeSCTList(encoded, &decoded));
  ASSERT_STREQ("abc", decoded[0].data());
  ASSERT_STREQ("def", decoded[1].data());
}

TEST_F(CtSerializationTest, FailsDecodingInvalidSCTList) {
  // A list with one item that's too short
  std::string_view encoded("\x0\xa\x0\x3\x61\x62\x63\x0\x5\x64\x65\x66", 12);
  std::vector<std::string_view> decoded;

  ASSERT_FALSE(ct::DecodeSCTList(encoded, &decoded));
}

TEST_F(CtSerializationTest, EncodeSignedCertificateTimestamp) {
  std::string encoded_test_sct(ct::GetTestSignedCertificateTimestamp());
  std::string_view encoded_sct(encoded_test_sct);

  scoped_refptr<ct::SignedCertificateTimestamp> sct;
  ASSERT_TRUE(ct::DecodeSignedCertificateTimestamp(&encoded_sct, &sct));

  std::string serialized;
  ASSERT_TRUE(ct::EncodeSignedCertificateTimestamp(sct, &serialized));
  EXPECT_EQ(serialized, encoded_test_sct);
}

TEST_F(CtSerializationTest, DecodesSignedCertificateTimestamp) {
  std::string encoded_test_sct(ct::GetTestSignedCertificateTimestamp());
  std::string_view encoded_sct(encoded_test_sct);

  scoped_refptr<ct::SignedCertificateTimestamp> sct;
  ASSERT_TRUE(ct::DecodeSignedCertificateTimestamp(&encoded_sct, &sct));
  EXPECT_EQ(0, sct->version);
  EXPECT_EQ(ct::GetTestPublicKeyId(), sct->log_id);
  base::Time expected_time =
      base::Time::UnixEpoch() + base::Milliseconds(1365181456089);
  EXPECT_EQ(expected_time, sct->timestamp);
  // Subtracting 4 bytes for signature data (hash & sig algs),
  // actual signature data should be 71 bytes.
  EXPECT_EQ((size_t) 71, sct->signature.signature_data.size());
  EXPECT_TRUE(sct->extensions.empty());
}

TEST_F(CtSerializationTest, FailsDecodingInvalidSignedCertificateTimestamp) {
  // Invalid version
  std::string_view invalid_version_sct("\x2\x0", 2);
  scoped_refptr<ct::SignedCertificateTimestamp> sct;

  ASSERT_FALSE(
      ct::DecodeSignedCertificateTimestamp(&invalid_version_sct, &sct));

  // Valid version, invalid length (missing data)
  std::string_view invalid_length_sct("\x0\xa\xb\xc", 4);
  ASSERT_FALSE(
      ct::DecodeSignedCertificateTimestamp(&invalid_length_sct, &sct));
}

TEST_F(CtSerializationTest, EncodesMerkleTreeLeafForX509Cert) {
  ct::MerkleTreeLeaf tree_leaf;
  ct::GetX509CertTreeLeaf(&tree_leaf);

  std::string encoded;
  ASSERT_TRUE(ct::EncodeTreeLeaf(tree_leaf, &encoded));
  EXPECT_EQ(741u, encoded.size()) << "Merkle tree leaf encoded incorrectly";
  EXPECT_EQ(std::string("\x00", 1), encoded.substr(0, 1)) <<
      "Version encoded incorrectly";
  EXPECT_EQ(std::string("\x00", 1), encoded.substr(1, 1)) <<
      "Merkle tree leaf type encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x00\x01\x45\x3c\x5f\xb8\x35", 8),
            encoded.substr(2, 8)) <<
      "Timestamp encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x00", 2), encoded.substr(10, 2)) <<
      "Log entry type encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x02\xce", 3), encoded.substr(12, 3)) <<
      "Certificate length encoded incorrectly";
  EXPECT_EQ(tree_leaf.signed_entry.leaf_certificate, encoded.substr(15, 718))
      << "Certificate encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x06", 2), encoded.substr(733, 2)) <<
      "CT extensions length encoded incorrectly";
  EXPECT_EQ(tree_leaf.extensions, encoded.substr(735, 6)) <<
      "CT extensions encoded incorrectly";
}

TEST_F(CtSerializationTest, EncodesMerkleTreeLeafForPrecert) {
  ct::MerkleTreeLeaf tree_leaf;
  ct::GetPrecertTreeLeaf(&tree_leaf);

  std::string encoded;
  ASSERT_TRUE(ct::EncodeTreeLeaf(tree_leaf, &encoded));
  EXPECT_EQ(622u, encoded.size()) << "Merkle tree leaf encoded incorrectly";
  EXPECT_EQ(std::string("\x00", 1), encoded.substr(0, 1)) <<
      "Version encoded incorrectly";
  EXPECT_EQ(std::string("\x00", 1), encoded.substr(1, 1)) <<
      "Merkle tree leaf type encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x00\x01\x45\x3c\x5f\xb8\x35", 8),
            encoded.substr(2, 8)) <<
      "Timestamp encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x01", 2), encoded.substr(10, 2)) <<
      "Log entry type encoded incorrectly";
  EXPECT_THAT(encoded.substr(12, 32),
              ElementsAreArray(tree_leaf.signed_entry.issuer_key_hash))
      << "Issuer key hash encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x02\x37", 3), encoded.substr(44, 3)) <<
      "TBS certificate length encoded incorrectly";
  EXPECT_EQ(tree_leaf.signed_entry.tbs_certificate, encoded.substr(47, 567))
      << "TBS certificate encoded incorrectly";
  EXPECT_EQ(std::string("\x00\x06", 2), encoded.substr(614, 2)) <<
      "CT extensions length encoded incorrectly";
  EXPECT_EQ(tree_leaf.extensions, encoded.substr(616, 6)) <<
      "CT extensions encoded incorrectly";
}

TEST_F(CtSerializationTest, EncodesValidSignedTreeHead) {
  ct::SignedTreeHead signed_tree_head;
  ASSERT_TRUE(GetSampleSignedTreeHead(&signed_tree_head));

  std::string encoded;
  ASSERT_TRUE(ct::EncodeTreeHeadSignature(signed_tree_head, &encoded));
  // Expected size is 50 bytes:
  // Byte 0 is version, byte 1 is signature type
  // Bytes 2-9 are timestamp
  // Bytes 10-17 are tree size
  // Bytes 18-49 are sha256 root hash
  ASSERT_EQ(50u, encoded.length());
  std::string expected_buffer(
      "\x0\x1\x0\x0\x1\x45\x3c\x5f\xb8\x35\x0\x0\x0\x0\x0\x0\x0\x15", 18);
  expected_buffer.append(ct::GetSampleSTHSHA256RootHash());
  ASSERT_EQ(expected_buffer, encoded);
}

}  // namespace net