// Copyright 2016 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 "quiche/http2/decoder/http2_structure_decoder.h"

// Tests decoding all of the fixed size HTTP/2 structures (i.e. those defined in
// quiche/http2/http2_structures.h) using Http2StructureDecoder, which
// handles buffering of structures split across input buffer boundaries, and in
// turn uses DoDecode when it has all of a structure in a contiguous buffer.

// NOTE: This tests the first pair of Start and Resume, which don't take
// a remaining_payload parameter. The other pair are well tested via the
// payload decoder tests, though...
// TODO(jamessynge): Create type parameterized tests for Http2StructureDecoder
// where the type is the type of structure, and with testing of both pairs of
// Start and Resume methods; note that it appears that the first pair will be
// used only for Http2FrameHeader, and the other pair only for structures in the
// frame payload.

#include <stddef.h>

#include <cstdint>
#include <string>

#include "absl/strings/string_view.h"
#include "quiche/http2/decoder/decode_buffer.h"
#include "quiche/http2/decoder/decode_status.h"
#include "quiche/http2/http2_constants.h"
#include "quiche/http2/test_tools/http2_frame_builder.h"
#include "quiche/http2/test_tools/http2_structures_test_util.h"
#include "quiche/http2/test_tools/random_decoder_test.h"
#include "quiche/common/platform/api/quiche_logging.h"
#include "quiche/common/platform/api/quiche_test_helpers.h"

using ::testing::AssertionSuccess;

namespace http2 {
namespace test {
namespace {
const bool kMayReturnZeroOnFirst = false;

template <class S>
class Http2StructureDecoderTest : public RandomDecoderTest {
 protected:
  typedef S Structure;

  Http2StructureDecoderTest() {
    // IF the test adds more data after the encoded structure, stop as
    // soon as the structure is decoded.
    stop_decode_on_done_ = true;
  }

  DecodeStatus StartDecoding(DecodeBuffer* b) override {
    // Overwrite the current contents of |structure_|, into which we'll
    // decode the buffer, so that we can be confident that we really decoded
    // the structure every time.
    structure_ = std::make_unique<S>();
    uint32_t old_remaining = b->Remaining();
    if (structure_decoder_.Start(structure_.get(), b)) {
      EXPECT_EQ(old_remaining - S::EncodedSize(), b->Remaining());
      ++fast_decode_count_;
      return DecodeStatus::kDecodeDone;
    } else {
      EXPECT_LT(structure_decoder_.offset(), S::EncodedSize());
      EXPECT_EQ(0u, b->Remaining());
      EXPECT_EQ(old_remaining - structure_decoder_.offset(), b->Remaining());
      ++incomplete_start_count_;
      return DecodeStatus::kDecodeInProgress;
    }
  }

  DecodeStatus ResumeDecoding(DecodeBuffer* b) override {
    uint32_t old_offset = structure_decoder_.offset();
    EXPECT_LT(old_offset, S::EncodedSize());
    uint32_t avail = b->Remaining();
    if (structure_decoder_.Resume(structure_.get(), b)) {
      EXPECT_LE(S::EncodedSize(), old_offset + avail);
      EXPECT_EQ(b->Remaining(), avail - (S::EncodedSize() - old_offset));
      ++slow_decode_count_;
      return DecodeStatus::kDecodeDone;
    } else {
      EXPECT_LT(structure_decoder_.offset(), S::EncodedSize());
      EXPECT_EQ(0u, b->Remaining());
      EXPECT_GT(S::EncodedSize(), old_offset + avail);
      ++incomplete_resume_count_;
      return DecodeStatus::kDecodeInProgress;
    }
  }

  // Fully decodes the Structure at the start of data, and confirms it matches
  // *expected (if provided).
  AssertionResult DecodeLeadingStructure(const S* expected,
                                         absl::string_view data) {
    VERIFY_LE(S::EncodedSize(), data.size());
    DecodeBuffer original(data);

    // The validator is called after each of the several times that the input
    // DecodeBuffer is decoded, each with a different segmentation of the input.
    // Validate that structure_ matches the expected value, if provided.
    Validator validator;
    if (expected != nullptr) {
      validator = [expected, this](const DecodeBuffer& /*db*/,
                                   DecodeStatus /*status*/) -> AssertionResult {
        VERIFY_EQ(*expected, *structure_);
        return AssertionSuccess();
      };
    }

    // Before that, validate that decoding is done and that we've advanced
    // the cursor the expected amount.
    validator = ValidateDoneAndOffset(S::EncodedSize(), validator);

    // Decode several times, with several segmentations of the input buffer.
    fast_decode_count_ = 0;
    slow_decode_count_ = 0;
    incomplete_start_count_ = 0;
    incomplete_resume_count_ = 0;
    VERIFY_SUCCESS(DecodeAndValidateSeveralWays(
        &original, kMayReturnZeroOnFirst, validator));
    VERIFY_FALSE(HasFailure());
    VERIFY_EQ(S::EncodedSize(), structure_decoder_.offset());
    VERIFY_EQ(S::EncodedSize(), original.Offset());
    VERIFY_LT(0u, fast_decode_count_);
    VERIFY_LT(0u, slow_decode_count_);
    VERIFY_LT(0u, incomplete_start_count_);

    // If the structure is large enough so that SelectZeroOrOne will have
    // caused Resume to return false, check that occurred.
    if (S::EncodedSize() >= 2) {
      VERIFY_LE(0u, incomplete_resume_count_);
    } else {
      VERIFY_EQ(0u, incomplete_resume_count_);
    }
    if (expected != nullptr) {
      QUICHE_DVLOG(1) << "DecodeLeadingStructure expected: " << *expected;
      QUICHE_DVLOG(1) << "DecodeLeadingStructure   actual: " << *structure_;
      VERIFY_EQ(*expected, *structure_);
    }
    return AssertionSuccess();
  }

  template <size_t N>
  AssertionResult DecodeLeadingStructure(const char (&data)[N]) {
    return DecodeLeadingStructure(nullptr, absl::string_view(data, N));
  }

  template <size_t N>
  AssertionResult DecodeLeadingStructure(const unsigned char (&data)[N]) {
    return DecodeLeadingStructure(nullptr, ToStringPiece(data));
  }

  // Encode the structure |in_s| into bytes, then decode the bytes
  // and validate that the decoder produced the same field values.
  AssertionResult EncodeThenDecode(const S& in_s) {
    std::string bytes = SerializeStructure(in_s);
    VERIFY_EQ(S::EncodedSize(), bytes.size());
    return DecodeLeadingStructure(&in_s, bytes);
  }

  // Repeatedly fill a structure with random but valid contents, encode it, then
  // decode it, and finally validate that the decoded structure matches the
  // random input. Lather-rinse-and-repeat.
  AssertionResult TestDecodingRandomizedStructures(size_t count) {
    for (size_t i = 0; i < count; ++i) {
      Structure input;
      Randomize(&input, RandomPtr());
      VERIFY_SUCCESS(EncodeThenDecode(input));
    }
    return AssertionSuccess();
  }

  AssertionResult TestDecodingRandomizedStructures() {
    VERIFY_SUCCESS(TestDecodingRandomizedStructures(100));
    return AssertionSuccess();
  }

  uint32_t decode_offset_ = 0;
  std::unique_ptr<S> structure_;
  Http2StructureDecoder structure_decoder_;
  size_t fast_decode_count_ = 0;
  size_t slow_decode_count_ = 0;
  size_t incomplete_start_count_ = 0;
  size_t incomplete_resume_count_ = 0;
};

class Http2FrameHeaderDecoderTest
    : public Http2StructureDecoderTest<Http2FrameHeader> {};

TEST_F(Http2FrameHeaderDecoderTest, DecodesLiteral) {
  {
    // Realistic input.
    // clang-format off
    const char kData[] = {
        0x00, 0x00, 0x05,        // Payload length: 5
        0x01,                    // Frame type: HEADERS
        0x08,                    // Flags: PADDED
        0x00, 0x00, 0x00, 0x01,  // Stream ID: 1
        0x04,                    // Padding length: 4
        0x00, 0x00, 0x00, 0x00,  // Padding bytes
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(5u, structure_->payload_length);
    EXPECT_EQ(Http2FrameType::HEADERS, structure_->type);
    EXPECT_EQ(Http2FrameFlag::PADDED, structure_->flags);
    EXPECT_EQ(1u, structure_->stream_id);
  }
  {
    // Unlikely input.
    // clang-format off
    const unsigned char kData[] = {
        0xff, 0xff, 0xff,        // Payload length: uint24 max
        0xff,                    // Frame type: Unknown
        0xff,                    // Flags: Unknown/All
        0xff, 0xff, 0xff, 0xff,  // Stream ID: uint31 max, plus R-bit
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ((1u << 24) - 1u, structure_->payload_length);
    EXPECT_EQ(static_cast<Http2FrameType>(255), structure_->type);
    EXPECT_EQ(255, structure_->flags);
    EXPECT_EQ(0x7FFFFFFFu, structure_->stream_id);
  }
}

TEST_F(Http2FrameHeaderDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2PriorityFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2PriorityFields> {};

TEST_F(Http2PriorityFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const unsigned char kData[] = {
        0x80, 0x00, 0x00, 0x05,  // Exclusive (yes) and Dependency (5)
        0xff,                    // Weight: 256 (after adding 1)
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(5u, structure_->stream_dependency);
    EXPECT_EQ(256u, structure_->weight);
    EXPECT_EQ(true, structure_->is_exclusive);
  }
  {
    // clang-format off
    const unsigned char kData[] = {
        0x7f, 0xff, 0xff, 0xff,  // Excl. (no) and Dependency (uint31 max)
        0x00,                    // Weight: 1 (after adding 1)
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(StreamIdMask(), structure_->stream_dependency);
    EXPECT_EQ(1u, structure_->weight);
    EXPECT_FALSE(structure_->is_exclusive);
  }
}

TEST_F(Http2PriorityFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2RstStreamFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2RstStreamFields> {};

TEST_F(Http2RstStreamFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x00, 0x00, 0x01,  // Error: PROTOCOL_ERROR
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_TRUE(structure_->IsSupportedErrorCode());
    EXPECT_EQ(Http2ErrorCode::PROTOCOL_ERROR, structure_->error_code);
  }
  {
    // clang-format off
    const unsigned char kData[] = {
        0xff, 0xff, 0xff, 0xff,  // Error: max uint32 (Unknown error code)
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_FALSE(structure_->IsSupportedErrorCode());
    EXPECT_EQ(static_cast<Http2ErrorCode>(0xffffffff), structure_->error_code);
  }
}

TEST_F(Http2RstStreamFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2SettingFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2SettingFields> {};

TEST_F(Http2SettingFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x01,              // Setting: HEADER_TABLE_SIZE
        0x00, 0x00, 0x40, 0x00,  // Value: 16K
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_TRUE(structure_->IsSupportedParameter());
    EXPECT_EQ(Http2SettingsParameter::HEADER_TABLE_SIZE, structure_->parameter);
    EXPECT_EQ(1u << 14, structure_->value);
  }
  {
    // clang-format off
    const unsigned char kData[] = {
        0x00, 0x00,              // Setting: Unknown (0)
        0xff, 0xff, 0xff, 0xff,  // Value: max uint32
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_FALSE(structure_->IsSupportedParameter());
    EXPECT_EQ(static_cast<Http2SettingsParameter>(0), structure_->parameter);
  }
}

TEST_F(Http2SettingFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2PushPromiseFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2PushPromiseFields> {};

TEST_F(Http2PushPromiseFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const unsigned char kData[] = {
        0x00, 0x01, 0x8a, 0x92,  // Promised Stream ID: 101010
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(101010u, structure_->promised_stream_id);
  }
  {
    // Promised stream id has R-bit (reserved for future use) set, which
    // should be cleared by the decoder.
    // clang-format off
    const unsigned char kData[] = {
        // Promised Stream ID: max uint31 and R-bit
        0xff, 0xff, 0xff, 0xff,
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(StreamIdMask(), structure_->promised_stream_id);
  }
}

TEST_F(Http2PushPromiseFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2PingFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2PingFields> {};

TEST_F(Http2PingFieldsDecoderTest, DecodesLiteral) {
  {
    // Each byte is different, so can detect if order changed.
    const char kData[] = {
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
    };
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(ToStringPiece(kData), ToStringPiece(structure_->opaque_bytes));
  }
  {
    // All zeros, detect problems handling NULs.
    const char kData[] = {
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    };
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(ToStringPiece(kData), ToStringPiece(structure_->opaque_bytes));
  }
  {
    const unsigned char kData[] = {
        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
    };
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(ToStringPiece(kData), ToStringPiece(structure_->opaque_bytes));
  }
}

TEST_F(Http2PingFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2GoAwayFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2GoAwayFields> {};

TEST_F(Http2GoAwayFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x00, 0x00, 0x00,  // Last Stream ID: 0
        0x00, 0x00, 0x00, 0x00,  // Error: NO_ERROR (0)
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(0u, structure_->last_stream_id);
    EXPECT_TRUE(structure_->IsSupportedErrorCode());
    EXPECT_EQ(Http2ErrorCode::HTTP2_NO_ERROR, structure_->error_code);
  }
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x00, 0x00, 0x01,  // Last Stream ID: 1
        0x00, 0x00, 0x00, 0x0d,  // Error: HTTP_1_1_REQUIRED
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(1u, structure_->last_stream_id);
    EXPECT_TRUE(structure_->IsSupportedErrorCode());
    EXPECT_EQ(Http2ErrorCode::HTTP_1_1_REQUIRED, structure_->error_code);
  }
  {
    // clang-format off
    const unsigned char kData[] = {
        0xff, 0xff, 0xff, 0xff,  // Last Stream ID: max uint31 and R-bit
        0xff, 0xff, 0xff, 0xff,  // Error: max uint32 (Unknown error code)
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(StreamIdMask(), structure_->last_stream_id);  // No high-bit.
    EXPECT_FALSE(structure_->IsSupportedErrorCode());
    EXPECT_EQ(static_cast<Http2ErrorCode>(0xffffffff), structure_->error_code);
  }
}

TEST_F(Http2GoAwayFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2WindowUpdateFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2WindowUpdateFields> {};

TEST_F(Http2WindowUpdateFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x01, 0x00, 0x00,  // Window Size Increment: 2 ^ 16
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(1u << 16, structure_->window_size_increment);
  }
  {
    // Increment must be non-zero, but we need to be able to decode the invalid
    // zero to detect it.
    // clang-format off
    const char kData[] = {
        0x00, 0x00, 0x00, 0x00,  // Window Size Increment: 0
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(0u, structure_->window_size_increment);
  }
  {
    // Increment has R-bit (reserved for future use) set, which
    // should be cleared by the decoder.
    // clang-format off
    const unsigned char kData[] = {
        // Window Size Increment: max uint31 and R-bit
        0xff, 0xff, 0xff, 0xff,
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(StreamIdMask(), structure_->window_size_increment);
  }
}

TEST_F(Http2WindowUpdateFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

//------------------------------------------------------------------------------

class Http2AltSvcFieldsDecoderTest
    : public Http2StructureDecoderTest<Http2AltSvcFields> {};

TEST_F(Http2AltSvcFieldsDecoderTest, DecodesLiteral) {
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x00,  // Origin Length: 0
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(0, structure_->origin_length);
  }
  {
    // clang-format off
    const char kData[] = {
        0x00, 0x14,  // Origin Length: 20
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(20, structure_->origin_length);
  }
  {
    // clang-format off
    const unsigned char kData[] = {
        0xff, 0xff,  // Origin Length: uint16 max
    };
    // clang-format on
    ASSERT_TRUE(DecodeLeadingStructure(kData));
    EXPECT_EQ(65535, structure_->origin_length);
  }
}

TEST_F(Http2AltSvcFieldsDecoderTest, DecodesRandomized) {
  EXPECT_TRUE(TestDecodingRandomizedStructures());
}

}  // namespace
}  // namespace test
}  // namespace http2