github.com/ooni/psiphon/tunnel-core@v0.0.0-20230105123940-fe12a24c96ee/oovendor/quic-go/internal/protocol/protocol.go (about)

     1  package protocol
     2  
     3  import (
     4  	"fmt"
     5  	"time"
     6  )
     7  
     8  // The PacketType is the Long Header Type
     9  type PacketType uint8
    10  
    11  const (
    12  	// PacketTypeInitial is the packet type of an Initial packet
    13  	PacketTypeInitial PacketType = 1 + iota
    14  	// PacketTypeRetry is the packet type of a Retry packet
    15  	PacketTypeRetry
    16  	// PacketTypeHandshake is the packet type of a Handshake packet
    17  	PacketTypeHandshake
    18  	// PacketType0RTT is the packet type of a 0-RTT packet
    19  	PacketType0RTT
    20  )
    21  
    22  func (t PacketType) String() string {
    23  	switch t {
    24  	case PacketTypeInitial:
    25  		return "Initial"
    26  	case PacketTypeRetry:
    27  		return "Retry"
    28  	case PacketTypeHandshake:
    29  		return "Handshake"
    30  	case PacketType0RTT:
    31  		return "0-RTT Protected"
    32  	default:
    33  		return fmt.Sprintf("unknown packet type: %d", t)
    34  	}
    35  }
    36  
    37  type ECN uint8
    38  
    39  const (
    40  	ECNNon ECN = iota // 00
    41  	ECT1              // 01
    42  	ECT0              // 10
    43  	ECNCE             // 11
    44  )
    45  
    46  // A ByteCount in QUIC
    47  type ByteCount int64
    48  
    49  // MaxByteCount is the maximum value of a ByteCount
    50  const MaxByteCount = ByteCount(1<<62 - 1)
    51  
    52  // InvalidByteCount is an invalid byte count
    53  const InvalidByteCount ByteCount = -1
    54  
    55  // A StatelessResetToken is a stateless reset token.
    56  type StatelessResetToken [16]byte
    57  
    58  // MaxPacketBufferSize maximum packet size of any QUIC packet, based on
    59  // ethernet's max size, minus the IP and UDP headers. IPv6 has a 40 byte header,
    60  // UDP adds an additional 8 bytes.  This is a total overhead of 48 bytes.
    61  // Ethernet's max packet size is 1500 bytes,  1500 - 48 = 1452.
    62  const MaxPacketBufferSize ByteCount = 1452
    63  
    64  // MinInitialPacketSize is the minimum size an Initial packet is required to have.
    65  const MinInitialPacketSize = 1200
    66  
    67  // MinUnknownVersionPacketSize is the minimum size a packet with an unknown version
    68  // needs to have in order to trigger a Version Negotiation packet.
    69  const MinUnknownVersionPacketSize = MinInitialPacketSize
    70  
    71  // MinStatelessResetSize is the minimum size of a stateless reset packet that we send
    72  const MinStatelessResetSize = 1 /* first byte */ + 20 /* max. conn ID length */ + 4 /* max. packet number length */ + 1 /* min. payload length */ + 16 /* token */
    73  
    74  // MinConnectionIDLenInitial is the minimum length of the destination connection ID on an Initial packet.
    75  const MinConnectionIDLenInitial = 8
    76  
    77  // DefaultAckDelayExponent is the default ack delay exponent
    78  const DefaultAckDelayExponent = 3
    79  
    80  // MaxAckDelayExponent is the maximum ack delay exponent
    81  const MaxAckDelayExponent = 20
    82  
    83  // DefaultMaxAckDelay is the default max_ack_delay
    84  const DefaultMaxAckDelay = 25 * time.Millisecond
    85  
    86  // MaxMaxAckDelay is the maximum max_ack_delay
    87  const MaxMaxAckDelay = (1<<14 - 1) * time.Millisecond
    88  
    89  // MaxConnIDLen is the maximum length of the connection ID
    90  const MaxConnIDLen = 20
    91  
    92  // InvalidPacketLimitAES is the maximum number of packets that we can fail to decrypt when using
    93  // AEAD_AES_128_GCM or AEAD_AES_265_GCM.
    94  const InvalidPacketLimitAES = 1 << 52
    95  
    96  // InvalidPacketLimitChaCha is the maximum number of packets that we can fail to decrypt when using AEAD_CHACHA20_POLY1305.
    97  const InvalidPacketLimitChaCha = 1 << 36