woodpecker/vendor/github.com/lucas-clemente/quic-go/protocol/version.go
2017-07-24 19:15:25 -04:00

55 lines
1.7 KiB
Go

package protocol
// VersionNumber is a version number as int
type VersionNumber int
// The version numbers, making grepping easier
const (
Version35 VersionNumber = 35 + iota
Version36
Version37
VersionWhatever VersionNumber = 0 // for when the version doesn't matter
VersionUnsupported VersionNumber = -1
)
// SupportedVersions lists the versions that the server supports
// must be in sorted descending order
var SupportedVersions = []VersionNumber{
Version37, Version36, Version35,
}
// VersionNumberToTag maps version numbers ('32') to tags ('Q032')
func VersionNumberToTag(vn VersionNumber) uint32 {
v := uint32(vn)
return 'Q' + ((v/100%10)+'0')<<8 + ((v/10%10)+'0')<<16 + ((v%10)+'0')<<24
}
// VersionTagToNumber is built from VersionNumberToTag in init()
func VersionTagToNumber(v uint32) VersionNumber {
return VersionNumber(((v>>8)&0xff-'0')*100 + ((v>>16)&0xff-'0')*10 + ((v>>24)&0xff - '0'))
}
// 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
// if no suitable version is found, it returns VersionUnsupported
func ChooseSupportedVersion(ours, theirs []VersionNumber) VersionNumber {
for _, ourVer := range ours {
for _, theirVer := range theirs {
if ourVer == theirVer {
return ourVer
}
}
}
return VersionUnsupported
}