115 lines
3.1 KiB
Go
115 lines
3.1 KiB
Go
package protocol
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import (
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"encoding/binary"
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"fmt"
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"math"
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"sync"
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"time"
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"golang.org/x/exp/rand"
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)
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// Version is a version number as int
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type Version uint32
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// gQUIC version range as defined in the wiki: https://github.com/quicwg/base-drafts/wiki/QUIC-Versions
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const (
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gquicVersion0 = 0x51303030
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maxGquicVersion = 0x51303439
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)
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// The version numbers, making grepping easier
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const (
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VersionUnknown Version = math.MaxUint32
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versionDraft29 Version = 0xff00001d // draft-29 used to be a widely deployed version
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Version1 Version = 0x1
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Version2 Version = 0x6b3343cf
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)
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// SupportedVersions lists the versions that the server supports
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// must be in sorted descending order
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var SupportedVersions = []Version{Version1, Version2}
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// IsValidVersion says if the version is known to quic-go
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func IsValidVersion(v Version) bool {
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return v == Version1 || IsSupportedVersion(SupportedVersions, v)
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}
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func (vn Version) String() string {
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//nolint:exhaustive
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switch vn {
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case VersionUnknown:
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return "unknown"
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case versionDraft29:
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return "draft-29"
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case Version1:
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return "v1"
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case Version2:
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return "v2"
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default:
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if vn.isGQUIC() {
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return fmt.Sprintf("gQUIC %d", vn.toGQUICVersion())
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}
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return fmt.Sprintf("%#x", uint32(vn))
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}
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}
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func (vn Version) isGQUIC() bool {
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return vn > gquicVersion0 && vn <= maxGquicVersion
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}
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func (vn Version) toGQUICVersion() int {
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return int(10*(vn-gquicVersion0)/0x100) + int(vn%0x10)
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}
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// IsSupportedVersion returns true if the server supports this version
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func IsSupportedVersion(supported []Version, v Version) bool {
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for _, t := range supported {
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if t == v {
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return true
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}
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}
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return false
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}
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// ChooseSupportedVersion finds the best version in the overlap of ours and theirs
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// ours is a slice of versions that we support, sorted by our preference (descending)
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// theirs is a slice of versions offered by the peer. The order does not matter.
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// The bool returned indicates if a matching version was found.
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func ChooseSupportedVersion(ours, theirs []Version) (Version, bool) {
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for _, ourVer := range ours {
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for _, theirVer := range theirs {
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if ourVer == theirVer {
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return ourVer, true
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}
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}
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}
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return 0, false
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}
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var (
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versionNegotiationMx sync.Mutex
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versionNegotiationRand = rand.New(rand.NewSource(uint64(time.Now().UnixNano())))
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)
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// generateReservedVersion generates a reserved version (v & 0x0f0f0f0f == 0x0a0a0a0a)
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func generateReservedVersion() Version {
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var b [4]byte
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_, _ = versionNegotiationRand.Read(b[:]) // ignore the error here. Failure to read random data doesn't break anything
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return Version((binary.BigEndian.Uint32(b[:]) | 0x0a0a0a0a) & 0xfafafafa)
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}
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// GetGreasedVersions adds one reserved version number to a slice of version numbers, at a random position.
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// It doesn't modify the supported slice.
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func GetGreasedVersions(supported []Version) []Version {
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versionNegotiationMx.Lock()
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defer versionNegotiationMx.Unlock()
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randPos := rand.Intn(len(supported) + 1)
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greased := make([]Version, len(supported)+1)
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copy(greased, supported[:randPos])
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greased[randPos] = generateReservedVersion()
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copy(greased[randPos+1:], supported[randPos:])
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return greased
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}
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