1package protocol 2 3import ( 4 "crypto/rand" 5 "encoding/binary" 6 "fmt" 7 "math" 8) 9 10// VersionNumber is a version number as int 11type VersionNumber uint32 12 13// gQUIC version range as defined in the wiki: https://github.com/quicwg/base-drafts/wiki/QUIC-Versions 14const ( 15 gquicVersion0 = 0x51303030 16 maxGquicVersion = 0x51303439 17) 18 19// The version numbers, making grepping easier 20const ( 21 VersionTLS VersionNumber = 0x1 22 VersionWhatever VersionNumber = math.MaxUint32 - 1 // for when the version doesn't matter 23 VersionUnknown VersionNumber = math.MaxUint32 24 VersionDraft29 VersionNumber = 0xff00001d 25 Version1 VersionNumber = 0x1 26) 27 28// SupportedVersions lists the versions that the server supports 29// must be in sorted descending order 30var SupportedVersions = []VersionNumber{Version1, VersionDraft29} 31 32// IsValidVersion says if the version is known to quic-go 33func IsValidVersion(v VersionNumber) bool { 34 return v == VersionTLS || IsSupportedVersion(SupportedVersions, v) 35} 36 37func (vn VersionNumber) String() string { 38 // For releases, VersionTLS will be set to a draft version. 39 // A switch statement can't contain duplicate cases. 40 if vn == VersionTLS && VersionTLS != VersionDraft29 && VersionTLS != Version1 { 41 return "TLS dev version (WIP)" 42 } 43 //nolint:exhaustive 44 switch vn { 45 case VersionWhatever: 46 return "whatever" 47 case VersionUnknown: 48 return "unknown" 49 case VersionDraft29: 50 return "draft-29" 51 case Version1: 52 return "v1" 53 default: 54 if vn.isGQUIC() { 55 return fmt.Sprintf("gQUIC %d", vn.toGQUICVersion()) 56 } 57 return fmt.Sprintf("%#x", uint32(vn)) 58 } 59} 60 61func (vn VersionNumber) isGQUIC() bool { 62 return vn > gquicVersion0 && vn <= maxGquicVersion 63} 64 65func (vn VersionNumber) toGQUICVersion() int { 66 return int(10*(vn-gquicVersion0)/0x100) + int(vn%0x10) 67} 68 69// IsSupportedVersion returns true if the server supports this version 70func IsSupportedVersion(supported []VersionNumber, v VersionNumber) bool { 71 for _, t := range supported { 72 if t == v { 73 return true 74 } 75 } 76 return false 77} 78 79// ChooseSupportedVersion finds the best version in the overlap of ours and theirs 80// ours is a slice of versions that we support, sorted by our preference (descending) 81// theirs is a slice of versions offered by the peer. The order does not matter. 82// The bool returned indicates if a matching version was found. 83func ChooseSupportedVersion(ours, theirs []VersionNumber) (VersionNumber, bool) { 84 for _, ourVer := range ours { 85 for _, theirVer := range theirs { 86 if ourVer == theirVer { 87 return ourVer, true 88 } 89 } 90 } 91 return 0, false 92} 93 94// generateReservedVersion generates a reserved version number (v & 0x0f0f0f0f == 0x0a0a0a0a) 95func generateReservedVersion() VersionNumber { 96 b := make([]byte, 4) 97 _, _ = rand.Read(b) // ignore the error here. Failure to read random data doesn't break anything 98 return VersionNumber((binary.BigEndian.Uint32(b) | 0x0a0a0a0a) & 0xfafafafa) 99} 100 101// GetGreasedVersions adds one reserved version number to a slice of version numbers, at a random position 102func GetGreasedVersions(supported []VersionNumber) []VersionNumber { 103 b := make([]byte, 1) 104 _, _ = rand.Read(b) // ignore the error here. Failure to read random data doesn't break anything 105 randPos := int(b[0]) % (len(supported) + 1) 106 greased := make([]VersionNumber, len(supported)+1) 107 copy(greased, supported[:randPos]) 108 greased[randPos] = generateReservedVersion() 109 copy(greased[randPos+1:], supported[randPos:]) 110 return greased 111} 112