| // 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. |
| |
| #ifndef NET_THIRD_PARTY_QUIC_CORE_QUIC_DATA_READER_H_ |
| #define NET_THIRD_PARTY_QUIC_CORE_QUIC_DATA_READER_H_ |
| |
| #include <cstddef> |
| #include <cstdint> |
| |
| #include "base/macros.h" |
| #include "net/third_party/quic/core/quic_types.h" |
| #include "net/third_party/quic/platform/api/quic_endian.h" |
| #include "net/third_party/quic/platform/api/quic_export.h" |
| #include "net/third_party/quic/platform/api/quic_string_piece.h" |
| |
| namespace quic { |
| |
| // Used for reading QUIC data. Though there isn't really anything terribly |
| // QUIC-specific here, it's a helper class that's useful when doing QUIC |
| // framing. |
| // |
| // To use, simply construct a QuicDataReader using the underlying buffer that |
| // you'd like to read fields from, then call one of the Read*() methods to |
| // actually do some reading. |
| // |
| // This class keeps an internal iterator to keep track of what's already been |
| // read and each successive Read*() call automatically increments said iterator |
| // on success. On failure, internal state of the QuicDataReader should not be |
| // trusted and it is up to the caller to throw away the failed instance and |
| // handle the error as appropriate. None of the Read*() methods should ever be |
| // called after failure, as they will also fail immediately. |
| class QUIC_EXPORT_PRIVATE QuicDataReader { |
| public: |
| // Constructs a reader using NETWORK_BYTE_ORDER endianness. |
| // Caller must provide an underlying buffer to work on. |
| QuicDataReader(const char* data, const size_t len); |
| // Constructs a reader using the specified endianness. |
| // Caller must provide an underlying buffer to work on. |
| QuicDataReader(const char* data, const size_t len, Endianness endianness); |
| QuicDataReader(const QuicDataReader&) = delete; |
| QuicDataReader& operator=(const QuicDataReader&) = delete; |
| |
| // Empty destructor. |
| ~QuicDataReader() {} |
| |
| // Reads an 8/16/32/64-bit unsigned integer into the given output |
| // parameter. Forwards the internal iterator on success. Returns true on |
| // success, false otherwise. |
| bool ReadUInt8(uint8_t* result); |
| bool ReadUInt16(uint16_t* result); |
| bool ReadUInt32(uint32_t* result); |
| bool ReadUInt64(uint64_t* result); |
| |
| // Set |result| to 0, then read |num_bytes| bytes in the correct byte order |
| // into least significant bytes of |result|. |
| bool ReadBytesToUInt64(size_t num_bytes, uint64_t* result); |
| |
| // Reads a 16-bit unsigned float into the given output parameter. |
| // Forwards the internal iterator on success. |
| // Returns true on success, false otherwise. |
| bool ReadUFloat16(uint64_t* result); |
| |
| // Reads a string prefixed with 16-bit length into the given output parameter. |
| // |
| // NOTE: Does not copy but rather references strings in the underlying buffer. |
| // This should be kept in mind when handling memory management! |
| // |
| // Forwards the internal iterator on success. |
| // Returns true on success, false otherwise. |
| bool ReadStringPiece16(QuicStringPiece* result); |
| |
| // Reads a given number of bytes into the given buffer. The buffer |
| // must be of adequate size. |
| // Forwards the internal iterator on success. |
| // Returns true on success, false otherwise. |
| bool ReadStringPiece(QuicStringPiece* result, size_t len); |
| |
| // Reads connection ID into the given output parameter. |
| // Forwards the internal iterator on success. |
| // Returns true on success, false otherwise. |
| bool ReadConnectionId(QuicConnectionId* connection_id, uint8_t length); |
| |
| // Reads tag represented as 32-bit unsigned integer into given output |
| // parameter. Tags are in big endian on the wire (e.g., CHLO is |
| // 'C','H','L','O') and are read in byte order, so tags in memory are in big |
| // endian. |
| bool ReadTag(uint32_t* tag); |
| |
| // Returns the remaining payload as a QuicStringPiece. |
| // |
| // NOTE: Does not copy but rather references strings in the underlying buffer. |
| // This should be kept in mind when handling memory management! |
| // |
| // Forwards the internal iterator. |
| QuicStringPiece ReadRemainingPayload(); |
| |
| // Returns the remaining payload as a QuicStringPiece. |
| // |
| // NOTE: Does not copy but rather references strings in the underlying buffer. |
| // This should be kept in mind when handling memory management! |
| // |
| // DOES NOT forward the internal iterator. |
| QuicStringPiece PeekRemainingPayload() const; |
| |
| // Reads a given number of bytes into the given buffer. The buffer |
| // must be of adequate size. |
| // Forwards the internal iterator on success. |
| // Returns true on success, false otherwise. |
| bool ReadBytes(void* result, size_t size); |
| |
| // Returns true if the entirety of the underlying buffer has been read via |
| // Read*() calls. |
| bool IsDoneReading() const; |
| |
| // Returns the length in bytes of a variable length integer based on the next |
| // two bits available. Returns 1, 2, 4, or 8 on success, and 0 on failure. |
| QuicVariableLengthIntegerLength PeekVarInt62Length(); |
| |
| // Returns the number of bytes remaining to be read. |
| size_t BytesRemaining() const; |
| |
| // Truncates the reader down by reducing its internal length. |
| // If called immediately after calling this, BytesRemaining will |
| // return |truncation_length|. If truncation_length is less than the |
| // current value of BytesRemaining, this does nothing and returns false. |
| bool TruncateRemaining(size_t truncation_length); |
| |
| // Returns the next byte that to be read. Must not be called when there are no |
| // bytes to be read. |
| // |
| // DOES NOT forward the internal iterator. |
| uint8_t PeekByte() const; |
| |
| void set_endianness(Endianness endianness) { endianness_ = endianness; } |
| |
| // Read an IETF-encoded Variable Length Integer and place the result |
| // in |*result|. |
| // Returns true if it works, false if not. The only error is that |
| // there is not enough in the buffer to read the number. |
| // If there is an error, |*result| is not altered. |
| // Numbers are encoded per the rules in draft-ietf-quic-transport-10.txt |
| // and that the integers in the range 0 ... (2^62)-1. |
| bool ReadVarInt62(uint64_t* result); |
| |
| // Convenience method that reads a StreamId. |
| // Atempts to read a Stream ID into |result| using ReadVarInt62 and |
| // returns false if there is a read error or if the value is |
| // greater than (2^32)-1. |
| bool ReadVarIntStreamId(QuicStreamId* result); |
| |
| QuicString DebugString() const; |
| |
| private: |
| // Returns true if the underlying buffer has enough room to read the given |
| // amount of bytes. |
| bool CanRead(size_t bytes) const; |
| |
| // To be called when a read fails for any reason. |
| void OnFailure(); |
| |
| // TODO(fkastenholz, b/73004262) change buffer_, et al, to be uint8_t, not |
| // char. The data buffer that we're reading from. |
| const char* data_; |
| |
| // The length of the data buffer that we're reading from. |
| size_t len_; |
| |
| // The location of the next read from our data buffer. |
| size_t pos_; |
| |
| // The endianness to read integers and floating numbers. |
| Endianness endianness_; |
| }; |
| |
| } // namespace quic |
| |
| #endif // NET_THIRD_PARTY_QUIC_CORE_QUIC_DATA_READER_H_ |