Project import generated by Copybara.
PiperOrigin-RevId: 237361882
Change-Id: I109a68f44db867b20f8c6a7732b0ce657133e52a
diff --git a/quic/core/quic_data_writer.cc b/quic/core/quic_data_writer.cc
new file mode 100644
index 0000000..c70bbdd
--- /dev/null
+++ b/quic/core/quic_data_writer.cc
@@ -0,0 +1,356 @@
+// 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 "net/third_party/quiche/src/quic/core/quic_data_writer.h"
+
+#include <algorithm>
+#include <limits>
+
+#include "net/third_party/quiche/src/quic/core/crypto/quic_random.h"
+#include "net/third_party/quiche/src/quic/core/quic_utils.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_bug_tracker.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_flags.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_str_cat.h"
+
+namespace quic {
+
+QuicDataWriter::QuicDataWriter(size_t size, char* buffer)
+ : QuicDataWriter(size, buffer, NETWORK_BYTE_ORDER) {}
+
+QuicDataWriter::QuicDataWriter(size_t size, char* buffer, Endianness endianness)
+ : buffer_(buffer), capacity_(size), length_(0), endianness_(endianness) {}
+
+QuicDataWriter::~QuicDataWriter() {}
+
+char* QuicDataWriter::data() {
+ return buffer_;
+}
+
+bool QuicDataWriter::WriteUInt8(uint8_t value) {
+ return WriteBytes(&value, sizeof(value));
+}
+
+bool QuicDataWriter::WriteUInt16(uint16_t value) {
+ if (endianness_ == NETWORK_BYTE_ORDER) {
+ value = QuicEndian::HostToNet16(value);
+ }
+ return WriteBytes(&value, sizeof(value));
+}
+
+bool QuicDataWriter::WriteUInt32(uint32_t value) {
+ if (endianness_ == NETWORK_BYTE_ORDER) {
+ value = QuicEndian::HostToNet32(value);
+ }
+ return WriteBytes(&value, sizeof(value));
+}
+
+bool QuicDataWriter::WriteUInt64(uint64_t value) {
+ if (endianness_ == NETWORK_BYTE_ORDER) {
+ value = QuicEndian::HostToNet64(value);
+ }
+ return WriteBytes(&value, sizeof(value));
+}
+
+bool QuicDataWriter::WriteBytesToUInt64(size_t num_bytes, uint64_t value) {
+ if (num_bytes > sizeof(value)) {
+ return false;
+ }
+ if (endianness_ == HOST_BYTE_ORDER) {
+ return WriteBytes(&value, num_bytes);
+ }
+
+ value = QuicEndian::HostToNet64(value);
+ return WriteBytes(reinterpret_cast<char*>(&value) + sizeof(value) - num_bytes,
+ num_bytes);
+}
+
+bool QuicDataWriter::WriteUFloat16(uint64_t value) {
+ uint16_t result;
+ if (value < (UINT64_C(1) << kUFloat16MantissaEffectiveBits)) {
+ // Fast path: either the value is denormalized, or has exponent zero.
+ // Both cases are represented by the value itself.
+ result = static_cast<uint16_t>(value);
+ } else if (value >= kUFloat16MaxValue) {
+ // Value is out of range; clamp it to the maximum representable.
+ result = std::numeric_limits<uint16_t>::max();
+ } else {
+ // The highest bit is between position 13 and 42 (zero-based), which
+ // corresponds to exponent 1-30. In the output, mantissa is from 0 to 10,
+ // hidden bit is 11 and exponent is 11 to 15. Shift the highest bit to 11
+ // and count the shifts.
+ uint16_t exponent = 0;
+ for (uint16_t offset = 16; offset > 0; offset /= 2) {
+ // Right-shift the value until the highest bit is in position 11.
+ // For offset of 16, 8, 4, 2 and 1 (binary search over 1-30),
+ // shift if the bit is at or above 11 + offset.
+ if (value >= (UINT64_C(1) << (kUFloat16MantissaBits + offset))) {
+ exponent += offset;
+ value >>= offset;
+ }
+ }
+
+ DCHECK_GE(exponent, 1);
+ DCHECK_LE(exponent, kUFloat16MaxExponent);
+ DCHECK_GE(value, UINT64_C(1) << kUFloat16MantissaBits);
+ DCHECK_LT(value, UINT64_C(1) << kUFloat16MantissaEffectiveBits);
+
+ // Hidden bit (position 11) is set. We should remove it and increment the
+ // exponent. Equivalently, we just add it to the exponent.
+ // This hides the bit.
+ result = static_cast<uint16_t>(value + (exponent << kUFloat16MantissaBits));
+ }
+
+ if (endianness_ == NETWORK_BYTE_ORDER) {
+ result = QuicEndian::HostToNet16(result);
+ }
+ return WriteBytes(&result, sizeof(result));
+}
+
+bool QuicDataWriter::WriteStringPiece16(QuicStringPiece val) {
+ if (val.size() > std::numeric_limits<uint16_t>::max()) {
+ return false;
+ }
+ if (!WriteUInt16(static_cast<uint16_t>(val.size()))) {
+ return false;
+ }
+ return WriteBytes(val.data(), val.size());
+}
+
+bool QuicDataWriter::WriteStringPiece(QuicStringPiece val) {
+ return WriteBytes(val.data(), val.size());
+}
+
+char* QuicDataWriter::BeginWrite(size_t length) {
+ if (length_ > capacity_) {
+ return nullptr;
+ }
+
+ if (capacity_ - length_ < length) {
+ return nullptr;
+ }
+
+#ifdef ARCH_CPU_64_BITS
+ DCHECK_LE(length, std::numeric_limits<uint32_t>::max());
+#endif
+
+ return buffer_ + length_;
+}
+
+bool QuicDataWriter::WriteBytes(const void* data, size_t data_len) {
+ char* dest = BeginWrite(data_len);
+ if (!dest) {
+ return false;
+ }
+
+ memcpy(dest, data, data_len);
+
+ length_ += data_len;
+ return true;
+}
+
+bool QuicDataWriter::WriteRepeatedByte(uint8_t byte, size_t count) {
+ char* dest = BeginWrite(count);
+ if (!dest) {
+ return false;
+ }
+
+ memset(dest, byte, count);
+
+ length_ += count;
+ return true;
+}
+
+void QuicDataWriter::WritePadding() {
+ DCHECK_LE(length_, capacity_);
+ if (length_ > capacity_) {
+ return;
+ }
+ memset(buffer_ + length_, 0x00, capacity_ - length_);
+ length_ = capacity_;
+}
+
+bool QuicDataWriter::WritePaddingBytes(size_t count) {
+ return WriteRepeatedByte(0x00, count);
+}
+
+bool QuicDataWriter::WriteConnectionId(QuicConnectionId connection_id) {
+ if (connection_id.IsEmpty()) {
+ return true;
+ }
+ return WriteBytes(connection_id.data(), connection_id.length());
+}
+
+bool QuicDataWriter::WriteTag(uint32_t tag) {
+ return WriteBytes(&tag, sizeof(tag));
+}
+
+bool QuicDataWriter::WriteRandomBytes(QuicRandom* random, size_t length) {
+ char* dest = BeginWrite(length);
+ if (!dest) {
+ return false;
+ }
+
+ random->RandBytes(dest, length);
+ length_ += length;
+ return true;
+}
+
+// Converts a uint64_t into an IETF/Quic formatted Variable Length
+// Integer. IETF Variable Length Integers have 62 significant bits, so
+// the value to write must be in the range of 0..(2^62)-1.
+//
+// Performance notes
+//
+// Measurements and experiments showed that unrolling the four cases
+// like this and dereferencing next_ as we do (*(next_+n)) gains about
+// 10% over making a loop and dereferencing it as *(next_++)
+//
+// Using a register for next didn't help.
+//
+// Branches are ordered to increase the likelihood of the first being
+// taken.
+//
+// Low-level optimization is useful here because this function will be
+// called frequently, leading to outsize benefits.
+bool QuicDataWriter::WriteVarInt62(uint64_t value) {
+ DCHECK_EQ(endianness_, NETWORK_BYTE_ORDER);
+
+ size_t remaining = capacity_ - length_;
+ char* next = buffer_ + length_;
+
+ if ((value & kVarInt62ErrorMask) == 0) {
+ // We know the high 2 bits are 0 so |value| is legal.
+ // We can do the encoding.
+ if ((value & kVarInt62Mask8Bytes) != 0) {
+ // Someplace in the high-4 bytes is a 1-bit. Do an 8-byte
+ // encoding.
+ if (remaining >= 8) {
+ *(next + 0) = ((value >> 56) & 0x3f) + 0xc0;
+ *(next + 1) = (value >> 48) & 0xff;
+ *(next + 2) = (value >> 40) & 0xff;
+ *(next + 3) = (value >> 32) & 0xff;
+ *(next + 4) = (value >> 24) & 0xff;
+ *(next + 5) = (value >> 16) & 0xff;
+ *(next + 6) = (value >> 8) & 0xff;
+ *(next + 7) = value & 0xff;
+ length_ += 8;
+ return true;
+ }
+ return false;
+ }
+ // The high-order-4 bytes are all 0, check for a 1, 2, or 4-byte
+ // encoding
+ if ((value & kVarInt62Mask4Bytes) != 0) {
+ // The encoding will not fit into 2 bytes, Do a 4-byte
+ // encoding.
+ if (remaining >= 4) {
+ *(next + 0) = ((value >> 24) & 0x3f) + 0x80;
+ *(next + 1) = (value >> 16) & 0xff;
+ *(next + 2) = (value >> 8) & 0xff;
+ *(next + 3) = value & 0xff;
+ length_ += 4;
+ return true;
+ }
+ return false;
+ }
+ // The high-order bits are all 0. Check to see if the number
+ // can be encoded as one or two bytes. One byte encoding has
+ // only 6 significant bits (bits 0xffffffff ffffffc0 are all 0).
+ // Two byte encoding has more than 6, but 14 or less significant
+ // bits (bits 0xffffffff ffffc000 are 0 and 0x00000000 00003fc0
+ // are not 0)
+ if ((value & kVarInt62Mask2Bytes) != 0) {
+ // Do 2-byte encoding
+ if (remaining >= 2) {
+ *(next + 0) = ((value >> 8) & 0x3f) + 0x40;
+ *(next + 1) = (value)&0xff;
+ length_ += 2;
+ return true;
+ }
+ return false;
+ }
+ if (remaining >= 1) {
+ // Do 1-byte encoding
+ *next = (value & 0x3f);
+ length_ += 1;
+ return true;
+ }
+ return false;
+ }
+ // Can not encode, high 2 bits not 0
+ return false;
+}
+
+bool QuicDataWriter::WriteVarInt62(
+ uint64_t value,
+ QuicVariableLengthIntegerLength write_length) {
+ DCHECK_EQ(endianness_, NETWORK_BYTE_ORDER);
+
+ size_t remaining = capacity_ - length_;
+ if (remaining < write_length) {
+ return false;
+ }
+
+ const QuicVariableLengthIntegerLength min_length = GetVarInt62Len(value);
+ if (write_length < min_length) {
+ QUIC_BUG << "Cannot write value " << value << " with write_length "
+ << write_length;
+ return false;
+ }
+ if (write_length == min_length) {
+ return WriteVarInt62(value);
+ }
+
+ if (write_length == VARIABLE_LENGTH_INTEGER_LENGTH_2) {
+ return WriteUInt8(0b01000000) && WriteUInt8(value);
+ }
+ if (write_length == VARIABLE_LENGTH_INTEGER_LENGTH_4) {
+ return WriteUInt8(0b10000000) && WriteUInt8(0) && WriteUInt16(value);
+ }
+ if (write_length == VARIABLE_LENGTH_INTEGER_LENGTH_8) {
+ return WriteUInt8(0b11000000) && WriteUInt8(0) && WriteUInt16(0) &&
+ WriteUInt32(value);
+ }
+
+ QUIC_BUG << "Invalid write_length " << static_cast<int>(write_length);
+ return false;
+}
+
+// static
+QuicVariableLengthIntegerLength QuicDataWriter::GetVarInt62Len(uint64_t value) {
+ if ((value & kVarInt62ErrorMask) != 0) {
+ QUIC_BUG << "Attempted to encode a value, " << value
+ << ", that is too big for VarInt62";
+ return VARIABLE_LENGTH_INTEGER_LENGTH_0;
+ }
+ if ((value & kVarInt62Mask8Bytes) != 0) {
+ return VARIABLE_LENGTH_INTEGER_LENGTH_8;
+ }
+ if ((value & kVarInt62Mask4Bytes) != 0) {
+ return VARIABLE_LENGTH_INTEGER_LENGTH_4;
+ }
+ if ((value & kVarInt62Mask2Bytes) != 0) {
+ return VARIABLE_LENGTH_INTEGER_LENGTH_2;
+ }
+ return VARIABLE_LENGTH_INTEGER_LENGTH_1;
+}
+
+bool QuicDataWriter::WriteStringPieceVarInt62(
+ const QuicStringPiece& string_piece) {
+ if (!WriteVarInt62(string_piece.size())) {
+ return false;
+ }
+ if (!string_piece.empty()) {
+ if (!WriteBytes(string_piece.data(), string_piece.size())) {
+ return false;
+ }
+ }
+ return true;
+}
+
+QuicString QuicDataWriter::DebugString() const {
+ return QuicStrCat(" { capacity: ", capacity_, ", length: ", length_, " }");
+}
+
+} // namespace quic
