protocol

Documentation

Index

• Constants
• Variables
• func IsSupportedVersion(v VersionNumber) bool
• func VersionNumberToTag(vn VersionNumber) uint32
• type ByteCount
• type ConnectionID
• type EncryptionLevel
  • func (e EncryptionLevel) String() string
• type PacketNumber
  • func InferPacketNumber(packetNumberLength PacketNumberLen, lastPacketNumber PacketNumber, ...) PacketNumber
• type PacketNumberLen
  • func GetPacketNumberLength(packetNumber PacketNumber) PacketNumberLen
  • func GetPacketNumberLengthForPublicHeader(packetNumber PacketNumber, leastUnacked PacketNumber) PacketNumberLen
• type Perspective
• type StreamID
• type VersionNumber
  • func HighestSupportedVersion(other []VersionNumber) (bool, VersionNumber)
  • func VersionTagToNumber(v uint32) VersionNumber

Constants

const (
	Version35 VersionNumber = 35 + iota
	Version36
	VersionWhatever    = 0 // for when the version doesn't matter
	VersionUnsupported = -1
)

The version numbers, making grepping easier

const AckSendDelay = 25 * time.Millisecond

AckSendDelay is the maximum delay that can be applied to an ACK for a retransmittable packet This is the value Chromium is using

const ClientHelloMinimumSize = 1024

ClientHelloMinimumSize is the minimum size the server expects an inchoate CHLO to have.

const ClosedSessionDeleteTimeout = time.Minute

ClosedSessionDeleteTimeout the server ignores packets arriving on a connection that is already closed after this time all information about the old connection will be deleted

const ConnectionFlowControlMultiplier = 1.5

ConnectionFlowControlMultiplier determines how much larger the connection flow control windows needs to be relative to any stream's flow control window This is the value that Chromium is using

const CryptoMaxParams = 128

CryptoMaxParams is the upper limit for the number of parameters in a crypto message. Value taken from Chrome.

const CryptoParameterMaxLength = 4000

CryptoParameterMaxLength is the upper limit for the length of a parameter in a crypto message.

const DefaultIdleTimeout = 30 * time.Second

DefaultIdleTimeout is the default idle timeout, for the server

const DefaultMaxCongestionWindow = 1000

DefaultMaxCongestionWindow is the default for the max congestion window

const EphermalKeyLifetime = time.Minute

EphermalKeyLifetime is the lifetime of the ephermal key during the handshake, see handshake.getEphermalKEX.

const InitialCongestionWindow = 32

InitialCongestionWindow is the initial congestion window in QUIC packets

const InitialIdleTimeout = 5 * time.Second

InitialIdleTimeout is the timeout before the handshake succeeds.

const MaxByteCount = math.MaxUint64

MaxByteCount is the maximum value of a ByteCount

const MaxClientHellos = 3

MaxClientHellos is the maximum number of times we'll send a client hello The value 3 accounts for: * one failure due to an incorrect or missing source-address token * one failure due the server's certificate chain being unavailible and the server being unwilling to send it without a valid source-address token

const MaxFrameAndPublicHeaderSize = MaxPacketSize - 12 /*crypto signature*/

MaxFrameAndPublicHeaderSize is the maximum size of a QUIC frame plus PublicHeader

const MaxIdleTimeoutClient = 2 * time.Minute

MaxIdleTimeoutClient is the idle timeout that the client suggests to the server

const MaxIdleTimeoutServer = 1 * time.Minute

MaxIdleTimeoutServer is the maximum idle timeout that can be negotiated, for the server

const MaxIncomingDynamicStreamsPerConnection = 100

MaxIncomingDynamicStreamsPerConnection is the maximum value accepted for the incoming number of dynamic streams per connection

const MaxNewStreamIDDelta = 4 * MaxStreamsPerConnection

MaxNewStreamIDDelta is the maximum difference between and a newly opened Stream and the highest StreamID that a client has ever opened note that the number of streams is half this value, since the client can only open streams with open StreamID

const MaxPacketsReceivedBeforeAckSend = 20

MaxPacketsReceivedBeforeAckSend is the number of packets that can be received before an ACK frame is sent

const MaxSessionUnprocessedPackets = DefaultMaxCongestionWindow

MaxSessionUnprocessedPackets is the max number of packets stored in each session that are not yet processed.

const MaxStreamFrameSorterGaps = 1000

MaxStreamFrameSorterGaps is the maximum number of gaps between received StreamFrames prevents DoS attacks against the streamFrameSorter

const MaxStreamsMinimumIncrement = 10

MaxStreamsMinimumIncrement is the slack the client is allowed for the maximum number of streams per connection, needed e.g. when packets are out of order or dropped. The minimum of this absolute increment and the procentual increase specified by MaxStreamsMultiplier is used.

const MaxStreamsMultiplier = 1.1

MaxStreamsMultiplier is the slack the client is allowed for the maximum number of streams per connection, needed e.g. when packets are out of order or dropped. The minimum of this procentual increase and the absolute increment specified by MaxStreamsMinimumIncrement is used.

const MaxStreamsPerConnection = 100

MaxStreamsPerConnection is the maximum value accepted for the number of streams per connection

const MaxTimeForCryptoHandshake = 10 * time.Second

MaxTimeForCryptoHandshake is the default timeout for a connection until the crypto handshake succeeds.

const MaxTrackedReceivedAckRanges = DefaultMaxCongestionWindow

MaxTrackedReceivedAckRanges is the maximum number of ACK ranges tracked

const MaxTrackedReceivedPackets = 2 * DefaultMaxCongestionWindow

MaxTrackedReceivedPackets is the maximum number of received packets saved for doing the entropy calculations

const MaxTrackedSentPackets = 2 * DefaultMaxCongestionWindow

MaxTrackedSentPackets is maximum number of sent packets saved for either later retransmission or entropy calculation

const MaxTrackedSkippedPackets = 10

MaxTrackedSkippedPackets is the maximum number of skipped packet numbers the SentPacketHandler keep track of for Optimistic ACK attack mitigation

const MaxUndecryptablePackets = 10

MaxUndecryptablePackets limits the number of undecryptable packets that a session queues for later until it sends a public reset.

const NonForwardSecurePacketSizeReduction = 50

NonForwardSecurePacketSizeReduction is the number of bytes a non forward-secure packet has to be smaller than a forward-secure packet This makes sure that those packets can always be retransmitted without splitting the contained StreamFrames

const NumCachedCertificates = 128

NumCachedCertificates is the number of cached compressed certificate chains, each taking ~1K space

const PublicResetTimeout = 500 * time.Millisecond

PublicResetTimeout is the time to wait before sending a Public Reset when receiving too many undecryptable packets during the handshake This timeout allows the Go scheduler to switch to the Go rountine that reads the crypto stream and to escalate the crypto

const RetransmittablePacketsBeforeAck = 2

RetransmittablePacketsBeforeAck is the number of retransmittable that an ACK is sent for

const STKExpiryTimeSec = 24 * 60 * 60

STKExpiryTimeSec is the valid time of a source address token in seconds

Variables

var SupportedVersions = []VersionNumber{
	Version35, Version36,
}

SupportedVersions lists the versions that the server supports must be in sorted order

var SupportedVersionsAsString string

SupportedVersionsAsString is needed for the Alt-Scv HTTP header

var SupportedVersionsAsTags []byte

SupportedVersionsAsTags is needed for the SHLO crypto message

Functions

func IsSupportedVersion

func IsSupportedVersion(v VersionNumber) bool

IsSupportedVersion returns true if the server supports this version

func VersionNumberToTag

func VersionNumberToTag(vn VersionNumber) uint32

VersionNumberToTag maps version numbers ('32') to tags ('Q032')

Types

type ByteCount

type ByteCount uint64

A ByteCount in QUIC

const DefaultTCPMSS ByteCount = 1460

DefaultTCPMSS is the default maximum packet size used in the Linux TCP implementation. Used in QUIC for congestion window computations in bytes.

const InitialConnectionFlowControlWindow ByteCount = (1 << 14) // 16 kB

InitialConnectionFlowControlWindow is the initial connection-level flow control window for sending

const InitialStreamFlowControlWindow ByteCount = (1 << 14) // 16 kB

InitialStreamFlowControlWindow is the initial stream-level flow control window for sending

const MaxPacketSize ByteCount = 1350

MaxPacketSize is the maximum packet size, including the public header, that we use for sending packets This is the value used by Chromium for a QUIC packet sent using IPv6 (for IPv4 it would be 1370)

const MaxReceiveConnectionFlowControlWindowClient ByteCount = 15 * (1 << 20) // 15 MB

MaxReceiveConnectionFlowControlWindowClient is the connection-level flow control window for receiving data, for the server This is the value that Google servers are using

const MaxReceiveConnectionFlowControlWindowServer ByteCount = 1.5 * (1 << 20) // 1.5 MB

MaxReceiveConnectionFlowControlWindowServer is the connection-level flow control window for receiving data This is the value that Google servers are using

const MaxReceivePacketSize ByteCount = 1452

MaxReceivePacketSize maximum packet size of any QUIC packet, based on ethernet's max size, minus the IP and UDP headers. IPv6 has a 40 byte header, UDP adds an additional 8 bytes. This is a total overhead of 48 bytes. Ethernet's max packet size is 1500 bytes, 1500 - 48 = 1452.

const MaxReceiveStreamFlowControlWindowClient ByteCount = 6 * (1 << 20) // 6 MB

MaxReceiveStreamFlowControlWindowClient is the maximum stream-level flow control window for receiving data, for the client This is the value that Chromium is using

const MaxReceiveStreamFlowControlWindowServer ByteCount = 1 * (1 << 20) // 1 MB

MaxReceiveStreamFlowControlWindowServer is the maximum stream-level flow control window for receiving data This is the value that Google servers are using

const ReceiveConnectionFlowControlWindow ByteCount = (1 << 10) * 48 // 48 kB

ReceiveConnectionFlowControlWindow is the connection-level flow control window for receiving data This is the value that Google servers are using

const ReceiveStreamFlowControlWindow ByteCount = (1 << 10) * 32 // 32 kB

ReceiveStreamFlowControlWindow is the stream-level flow control window for receiving data This is the value that Google servers are using

type ConnectionID

type ConnectionID uint64

A ConnectionID in QUIC

type EncryptionLevel

type EncryptionLevel int

EncryptionLevel is the encryption level Default value is Unencrypted

const (
	// EncryptionUnspecified is a not specified encryption level
	EncryptionUnspecified EncryptionLevel = iota
	// EncryptionUnencrypted is not encrypted
	EncryptionUnencrypted
	// EncryptionSecure is encrypted, but not forward secure
	EncryptionSecure
	// EncryptionForwardSecure is forward secure
	EncryptionForwardSecure
)

func (EncryptionLevel) String

func (e EncryptionLevel) String() string

type PacketNumber

type PacketNumber uint64

A PacketNumber in QUIC

const SkipPacketAveragePeriodLength PacketNumber = 500

SkipPacketAveragePeriodLength is the average period length in which one packet number is skipped to prevent an Optimistic ACK attack

func InferPacketNumber

func InferPacketNumber(packetNumberLength PacketNumberLen, lastPacketNumber PacketNumber, wirePacketNumber PacketNumber) PacketNumber

InferPacketNumber calculates the packet number based on the received packet number, its length and the last seen packet number

type PacketNumberLen

type PacketNumberLen uint8

PacketNumberLen is the length of the packet number in bytes

const (
	// PacketNumberLenInvalid is the default value and not a valid length for a packet number
	PacketNumberLenInvalid PacketNumberLen = 0
	// PacketNumberLen1 is a packet number length of 1 byte
	PacketNumberLen1 PacketNumberLen = 1
	// PacketNumberLen2 is a packet number length of 2 bytes
	PacketNumberLen2 PacketNumberLen = 2
	// PacketNumberLen4 is a packet number length of 4 bytes
	PacketNumberLen4 PacketNumberLen = 4
	// PacketNumberLen6 is a packet number length of 6 bytes
	PacketNumberLen6 PacketNumberLen = 6
)

func GetPacketNumberLength

func GetPacketNumberLength(packetNumber PacketNumber) PacketNumberLen

GetPacketNumberLength gets the minimum length needed to fully represent the packet number

func GetPacketNumberLengthForPublicHeader

func GetPacketNumberLengthForPublicHeader(packetNumber PacketNumber, leastUnacked PacketNumber) PacketNumberLen

GetPacketNumberLengthForPublicHeader gets the length of the packet number for the public header it never chooses a PacketNumberLen of 1 byte, since this is too short under certain circumstances

type Perspective

type Perspective int

Perspective determines if we're acting as a server or a client

const (
	PerspectiveServer Perspective = 1
	PerspectiveClient Perspective = 2
)

the perspectives

type StreamID

type StreamID uint32

A StreamID in QUIC

type VersionNumber

type VersionNumber int

VersionNumber is a version number as int

func HighestSupportedVersion

func HighestSupportedVersion(other []VersionNumber) (bool, VersionNumber)

HighestSupportedVersion finds the highest version number that is both present in other and in SupportedVersions the versions in other do not need to be ordered it returns true and the version number, if there is one, otherwise false

func VersionTagToNumber

func VersionTagToNumber(v uint32) VersionNumber

VersionTagToNumber is built from VersionNumberToTag in init()