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@@ -0,0 +1,253 @@
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+package crypt
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+
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+import (
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+ "strings"
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+)
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+
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+type CurveID uint16
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+type SignatureScheme uint16
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+
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+const (
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+ statusTypeOCSP uint8 = 1
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+ extensionServerName uint16 = 0
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+ extensionStatusRequest uint16 = 5
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+ extensionSupportedCurves uint16 = 10
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+ extensionSupportedPoints uint16 = 11
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+ extensionSignatureAlgorithms uint16 = 13
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+ extensionALPN uint16 = 16
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+ extensionSCT uint16 = 18 // https://tools.ietf.org/html/rfc6962#section-6
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+ extensionSessionTicket uint16 = 35
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+ extensionNextProtoNeg uint16 = 13172 // not IANA assigned
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+ extensionRenegotiationInfo uint16 = 0xff01
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+ scsvRenegotiation uint16 = 0x00ff
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+)
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+
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+type ClientHelloMsg struct {
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+ raw []byte
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+ vers uint16
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+ random []byte
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+ sessionId []byte
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+ cipherSuites []uint16
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+ compressionMethods []uint8
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+ nextProtoNeg bool
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+ serverName string
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+ ocspStapling bool
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+ scts bool
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+ supportedCurves []CurveID
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+ supportedPoints []uint8
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+ ticketSupported bool
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+ sessionTicket []uint8
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+ supportedSignatureAlgorithms []SignatureScheme
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+ secureRenegotiation []byte
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+ secureRenegotiationSupported bool
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+ alpnProtocols []string
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+}
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+
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+func (m *ClientHelloMsg) GetServerName() string {
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+ return m.serverName
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+}
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+
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+func (m *ClientHelloMsg) Unmarshal(data []byte) bool {
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+ if len(data) < 42 {
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+ return false
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+ }
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+ m.raw = data
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+ m.vers = uint16(data[4])<<8 | uint16(data[5])
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+ m.random = data[6:38]
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+ sessionIdLen := int(data[38])
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+ if sessionIdLen > 32 || len(data) < 39+sessionIdLen {
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+ return false
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+ }
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+ m.sessionId = data[39 : 39+sessionIdLen]
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+ data = data[39+sessionIdLen:]
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+ if len(data) < 2 {
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+ return false
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+ }
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+ // cipherSuiteLen is the number of bytes of cipher suite numbers. Since
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+ // they are uint16s, the number must be even.
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+ cipherSuiteLen := int(data[0])<<8 | int(data[1])
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+ if cipherSuiteLen%2 == 1 || len(data) < 2+cipherSuiteLen {
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+ return false
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+ }
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+ numCipherSuites := cipherSuiteLen / 2
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+ m.cipherSuites = make([]uint16, numCipherSuites)
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+ for i := 0; i < numCipherSuites; i++ {
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+ m.cipherSuites[i] = uint16(data[2+2*i])<<8 | uint16(data[3+2*i])
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+ if m.cipherSuites[i] == scsvRenegotiation {
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+ m.secureRenegotiationSupported = true
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+ }
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+ }
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+ data = data[2+cipherSuiteLen:]
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+ if len(data) < 1 {
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+ return false
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+ }
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+ compressionMethodsLen := int(data[0])
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+ if len(data) < 1+compressionMethodsLen {
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+ return false
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+ }
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+ m.compressionMethods = data[1 : 1+compressionMethodsLen]
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+ data = data[1+compressionMethodsLen:]
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+
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+ m.nextProtoNeg = false
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+ m.serverName = ""
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+ m.ocspStapling = false
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+ m.ticketSupported = false
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+ m.sessionTicket = nil
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+ m.supportedSignatureAlgorithms = nil
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+ m.alpnProtocols = nil
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+ m.scts = false
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+
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+ if len(data) == 0 {
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+ // ClientHello is optionally followed by extension data
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+ return true
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+ }
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+ if len(data) < 2 {
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+ return false
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+ }
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+
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+ extensionsLength := int(data[0])<<8 | int(data[1])
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+ data = data[2:]
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+ if extensionsLength != len(data) {
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+ return false
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+ }
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+
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+ for len(data) != 0 {
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+ if len(data) < 4 {
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+ return false
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+ }
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+ extension := uint16(data[0])<<8 | uint16(data[1])
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+ length := int(data[2])<<8 | int(data[3])
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+ data = data[4:]
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+ if len(data) < length {
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+ return false
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+ }
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+
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+ switch extension {
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+ case extensionServerName:
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+ d := data[:length]
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+ if len(d) < 2 {
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+ return false
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+ }
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+ namesLen := int(d[0])<<8 | int(d[1])
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+ d = d[2:]
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+ if len(d) != namesLen {
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+ return false
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+ }
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+ for len(d) > 0 {
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+ if len(d) < 3 {
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+ return false
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+ }
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+ nameType := d[0]
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+ nameLen := int(d[1])<<8 | int(d[2])
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+ d = d[3:]
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+ if len(d) < nameLen {
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+ return false
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+ }
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+ if nameType == 0 {
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+ m.serverName = string(d[:nameLen])
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+ // An SNI value may not include a
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+ // trailing dot. See
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+ // https://tools.ietf.org/html/rfc6066#section-3.
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+ if strings.HasSuffix(m.serverName, ".") {
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+ return false
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+ }
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+ break
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+ }
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+ d = d[nameLen:]
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+ }
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+ case extensionNextProtoNeg:
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+ if length > 0 {
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+ return false
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+ }
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+ m.nextProtoNeg = true
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+ case extensionStatusRequest:
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+ m.ocspStapling = length > 0 && data[0] == statusTypeOCSP
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+ case extensionSupportedCurves:
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+ // https://tools.ietf.org/html/rfc4492#section-5.5.1
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+ if length < 2 {
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+ return false
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+ }
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+ l := int(data[0])<<8 | int(data[1])
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+ if l%2 == 1 || length != l+2 {
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+ return false
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+ }
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+ numCurves := l / 2
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+ m.supportedCurves = make([]CurveID, numCurves)
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+ d := data[2:]
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+ for i := 0; i < numCurves; i++ {
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+ m.supportedCurves[i] = CurveID(d[0])<<8 | CurveID(d[1])
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+ d = d[2:]
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+ }
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+ case extensionSupportedPoints:
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+ // https://tools.ietf.org/html/rfc4492#section-5.5.2
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+ if length < 1 {
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+ return false
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+ }
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+ l := int(data[0])
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+ if length != l+1 {
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+ return false
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+ }
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+ m.supportedPoints = make([]uint8, l)
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+ copy(m.supportedPoints, data[1:])
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+ case extensionSessionTicket:
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+ // https://tools.ietf.org/html/rfc5077#section-3.2
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+ m.ticketSupported = true
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+ m.sessionTicket = data[:length]
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+ case extensionSignatureAlgorithms:
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+ // https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
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+ if length < 2 || length&1 != 0 {
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+ return false
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+ }
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+ l := int(data[0])<<8 | int(data[1])
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+ if l != length-2 {
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+ return false
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+ }
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+ n := l / 2
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+ d := data[2:]
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+ m.supportedSignatureAlgorithms = make([]SignatureScheme, n)
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+ for i := range m.supportedSignatureAlgorithms {
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+ m.supportedSignatureAlgorithms[i] = SignatureScheme(d[0])<<8 | SignatureScheme(d[1])
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+ d = d[2:]
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+ }
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+ case extensionRenegotiationInfo:
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+ if length == 0 {
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+ return false
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+ }
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+ d := data[:length]
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+ l := int(d[0])
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+ d = d[1:]
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+ if l != len(d) {
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+ return false
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+ }
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+
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+ m.secureRenegotiation = d
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+ m.secureRenegotiationSupported = true
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+ case extensionALPN:
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+ if length < 2 {
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+ return false
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+ }
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+ l := int(data[0])<<8 | int(data[1])
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+ if l != length-2 {
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+ return false
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+ }
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+ d := data[2:length]
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+ for len(d) != 0 {
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+ stringLen := int(d[0])
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+ d = d[1:]
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+ if stringLen == 0 || stringLen > len(d) {
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+ return false
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+ }
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+ m.alpnProtocols = append(m.alpnProtocols, string(d[:stringLen]))
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+ d = d[stringLen:]
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+ }
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+ case extensionSCT:
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+ m.scts = true
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+ if length != 0 {
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+ return false
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+ }
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+ }
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+ data = data[length:]
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+ }
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+
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+ return true
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+}
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