| // Copyright 2018 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 QUICHE_QUIC_CORE_QUIC_CONNECTION_ID_H_ |
| #define QUICHE_QUIC_CORE_QUIC_CONNECTION_ID_H_ |
| |
| #include <string> |
| #include <vector> |
| |
| #include "absl/types/span.h" |
| #include "quiche/quic/platform/api/quic_export.h" |
| |
| namespace quic { |
| |
| enum QuicConnectionIdLength { |
| PACKET_0BYTE_CONNECTION_ID = 0, |
| PACKET_8BYTE_CONNECTION_ID = 8, |
| }; |
| |
| // This is a property of QUIC headers, it indicates whether the connection ID |
| // should actually be sent over the wire (or was sent on received packets). |
| enum QuicConnectionIdIncluded : uint8_t { |
| CONNECTION_ID_PRESENT = 1, |
| CONNECTION_ID_ABSENT = 2, |
| }; |
| |
| // Maximum connection ID length supported by versions that use the encoding from |
| // draft-ietf-quic-invariants-06. |
| const uint8_t kQuicMaxConnectionIdWithLengthPrefixLength = 20; |
| |
| // Maximum connection ID length supported by versions that use the encoding from |
| // draft-ietf-quic-invariants-05. |
| const uint8_t kQuicMaxConnectionId4BitLength = 18; |
| |
| // kQuicDefaultConnectionIdLength is the only supported length for QUIC |
| // versions < v99, and is the default picked for all versions. |
| const uint8_t kQuicDefaultConnectionIdLength = 8; |
| |
| // According to the IETF spec, the initial server connection ID generated by |
| // the client must be at least this long. |
| const uint8_t kQuicMinimumInitialConnectionIdLength = 8; |
| |
| class QUIC_EXPORT_PRIVATE QuicConnectionId { |
| public: |
| // Creates a connection ID of length zero. |
| QuicConnectionId(); |
| |
| // Creates a connection ID from network order bytes. |
| QuicConnectionId(const char* data, uint8_t length); |
| QuicConnectionId(const absl::Span<const uint8_t> data); |
| |
| // Creates a connection ID from another connection ID. |
| QuicConnectionId(const QuicConnectionId& other); |
| |
| // Assignment operator. |
| QuicConnectionId& operator=(const QuicConnectionId& other); |
| |
| ~QuicConnectionId(); |
| |
| // Returns the length of the connection ID, in bytes. |
| uint8_t length() const; |
| |
| // Sets the length of the connection ID, in bytes. |
| // WARNING: Calling set_length() can change the in-memory location of the |
| // connection ID. Callers must therefore ensure they call data() or |
| // mutable_data() after they call set_length(). |
| void set_length(uint8_t length); |
| |
| // Returns a pointer to the connection ID bytes, in network byte order. |
| const char* data() const; |
| |
| // Returns a mutable pointer to the connection ID bytes, |
| // in network byte order. |
| char* mutable_data(); |
| |
| // Returns whether the connection ID has length zero. |
| bool IsEmpty() const; |
| |
| // Hash() is required to use connection IDs as keys in hash tables. |
| // During the lifetime of a process, the output of Hash() is guaranteed to be |
| // the same for connection IDs that are equal to one another. Note however |
| // that this property is not guaranteed across process lifetimes. This makes |
| // Hash() suitable for data structures such as hash tables but not for sending |
| // a hash over the network. |
| size_t Hash() const; |
| |
| // Generates an ASCII string that represents |
| // the contents of the connection ID, or "0" if it is empty. |
| std::string ToString() const; |
| |
| // operator<< allows easily logging connection IDs. |
| friend QUIC_EXPORT_PRIVATE std::ostream& operator<<( |
| std::ostream& os, const QuicConnectionId& v); |
| |
| bool operator==(const QuicConnectionId& v) const; |
| bool operator!=(const QuicConnectionId& v) const; |
| // operator< is required to use connection IDs as keys in hash tables. |
| bool operator<(const QuicConnectionId& v) const; |
| |
| private: |
| // The connection ID is represented in network byte order. |
| union { |
| // If the connection ID fits in |data_short_|, it is stored in the |
| // first |length_| bytes of |data_short_|. |
| // Otherwise it is stored in |data_long_| which is guaranteed to have a size |
| // equal to |length_|. |
| // A value of 11 was chosen because our commonly used connection ID length |
| // is 8 and with the length, the class is padded to at least 12 bytes |
| // anyway. |
| struct { |
| uint8_t padding_; // Match length_ field of the other union member. |
| char data_short_[11]; |
| }; |
| struct { |
| uint8_t length_; // length of the connection ID, in bytes. |
| char* data_long_; |
| }; |
| }; |
| }; |
| |
| // Creates a connection ID of length zero, unless the restart flag |
| // quic_connection_ids_network_byte_order is false in which case |
| // it returns an 8-byte all-zeroes connection ID. |
| QUIC_EXPORT_PRIVATE QuicConnectionId EmptyQuicConnectionId(); |
| |
| // QuicConnectionIdHash can be passed as hash argument to hash tables. |
| // During the lifetime of a process, the output of QuicConnectionIdHash is |
| // guaranteed to be the same for connection IDs that are equal to one another. |
| // Note however that this property is not guaranteed across process lifetimes. |
| // This makes QuicConnectionIdHash suitable for data structures such as hash |
| // tables but not for sending a hash over the network. |
| class QUIC_EXPORT_PRIVATE QuicConnectionIdHash { |
| public: |
| size_t operator()(QuicConnectionId const& connection_id) const noexcept { |
| return connection_id.Hash(); |
| } |
| }; |
| |
| } // namespace quic |
| |
| #endif // QUICHE_QUIC_CORE_QUIC_CONNECTION_ID_H_ |