cloudflared-mirror/vendor/github.com/lucas-clemente/quic-go/internal/protocol/version.go

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package protocol
import (
"crypto/rand"
"encoding/binary"
"fmt"
"math"
)
// VersionNumber is a version number as int
type VersionNumber uint32
// gQUIC version range as defined in the wiki: https://github.com/quicwg/base-drafts/wiki/QUIC-Versions
const (
gquicVersion0 = 0x51303030
maxGquicVersion = 0x51303439
)
// The version numbers, making grepping easier
const (
VersionTLS VersionNumber = 0x1
VersionWhatever VersionNumber = math.MaxUint32 - 1 // for when the version doesn't matter
VersionUnknown VersionNumber = math.MaxUint32
VersionDraft29 VersionNumber = 0xff00001d
Version1 VersionNumber = 0x1
Version2 VersionNumber = 0x709a50c4
)
// SupportedVersions lists the versions that the server supports
// must be in sorted descending order
var SupportedVersions = []VersionNumber{Version1, Version2, VersionDraft29}
// IsValidVersion says if the version is known to quic-go
func IsValidVersion(v VersionNumber) bool {
return v == VersionTLS || IsSupportedVersion(SupportedVersions, v)
}
func (vn VersionNumber) String() string {
// For releases, VersionTLS will be set to a draft version.
// A switch statement can't contain duplicate cases.
if vn == VersionTLS && VersionTLS != VersionDraft29 && VersionTLS != Version1 {
return "TLS dev version (WIP)"
}
//nolint:exhaustive
switch vn {
case VersionWhatever:
return "whatever"
case VersionUnknown:
return "unknown"
case VersionDraft29:
return "draft-29"
case Version1:
return "v1"
case Version2:
return "v2"
default:
if vn.isGQUIC() {
return fmt.Sprintf("gQUIC %d", vn.toGQUICVersion())
}
return fmt.Sprintf("%#x", uint32(vn))
}
}
func (vn VersionNumber) isGQUIC() bool {
return vn > gquicVersion0 && vn <= maxGquicVersion
}
func (vn VersionNumber) toGQUICVersion() int {
return int(10*(vn-gquicVersion0)/0x100) + int(vn%0x10)
}
// IsSupportedVersion returns true if the server supports this version
func IsSupportedVersion(supported []VersionNumber, v VersionNumber) bool {
for _, t := range supported {
if t == v {
return true
}
}
return false
}
// ChooseSupportedVersion finds the best version in the overlap of ours and theirs
// ours is a slice of versions that we support, sorted by our preference (descending)
// theirs is a slice of versions offered by the peer. The order does not matter.
// The bool returned indicates if a matching version was found.
func ChooseSupportedVersion(ours, theirs []VersionNumber) (VersionNumber, bool) {
for _, ourVer := range ours {
for _, theirVer := range theirs {
if ourVer == theirVer {
return ourVer, true
}
}
}
return 0, false
}
// generateReservedVersion generates a reserved version number (v & 0x0f0f0f0f == 0x0a0a0a0a)
func generateReservedVersion() VersionNumber {
b := make([]byte, 4)
_, _ = rand.Read(b) // ignore the error here. Failure to read random data doesn't break anything
return VersionNumber((binary.BigEndian.Uint32(b) | 0x0a0a0a0a) & 0xfafafafa)
}
// GetGreasedVersions adds one reserved version number to a slice of version numbers, at a random position
func GetGreasedVersions(supported []VersionNumber) []VersionNumber {
b := make([]byte, 1)
_, _ = rand.Read(b) // ignore the error here. Failure to read random data doesn't break anything
randPos := int(b[0]) % (len(supported) + 1)
greased := make([]VersionNumber, len(supported)+1)
copy(greased, supported[:randPos])
greased[randPos] = generateReservedVersion()
copy(greased[randPos+1:], supported[randPos:])
return greased
}