112 lines
3.4 KiB
Go
112 lines
3.4 KiB
Go
package protocol
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import (
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"crypto/rand"
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"encoding/binary"
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"fmt"
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"math"
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)
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// VersionNumber is a version number as int
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type VersionNumber 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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VersionTLS VersionNumber = 0x1
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VersionWhatever VersionNumber = math.MaxUint32 - 1 // for when the version doesn't matter
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VersionUnknown VersionNumber = math.MaxUint32
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VersionDraft29 VersionNumber = 0xff00001d
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Version1 VersionNumber = 0x1
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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 = []VersionNumber{Version1, VersionDraft29}
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// IsValidVersion says if the version is known to quic-go
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func IsValidVersion(v VersionNumber) bool {
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return v == VersionTLS || IsSupportedVersion(SupportedVersions, v)
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}
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func (vn VersionNumber) String() string {
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// For releases, VersionTLS will be set to a draft version.
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// A switch statement can't contain duplicate cases.
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if vn == VersionTLS && VersionTLS != VersionDraft29 && VersionTLS != Version1 {
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return "TLS dev version (WIP)"
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}
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//nolint:exhaustive
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switch vn {
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case VersionWhatever:
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return "whatever"
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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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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 VersionNumber) isGQUIC() bool {
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return vn > gquicVersion0 && vn <= maxGquicVersion
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}
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func (vn VersionNumber) 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 []VersionNumber, v VersionNumber) 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 []VersionNumber) (VersionNumber, 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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// generateReservedVersion generates a reserved version number (v & 0x0f0f0f0f == 0x0a0a0a0a)
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func generateReservedVersion() VersionNumber {
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b := make([]byte, 4)
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_, _ = rand.Read(b) // ignore the error here. Failure to read random data doesn't break anything
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return VersionNumber((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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func GetGreasedVersions(supported []VersionNumber) []VersionNumber {
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b := make([]byte, 1)
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_, _ = rand.Read(b) // ignore the error here. Failure to read random data doesn't break anything
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randPos := int(b[0]) % (len(supported) + 1)
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greased := make([]VersionNumber, 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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