[dev.boringcrypto] all: merge commit 57c115e1 into dev.boringcrypto

[gostls13.git] / src / crypto / tls / handshake_client.go

diff --git a/src/crypto/tls/handshake_client.go b/src/crypto/tls/handshake_client.go
index 9582a7f867514d9fedf63b218c08c27c131228bd..cd1b3b1d126c0cab68a911bf58f0be23f17a1a6b 100644 (file)
--- a/src/crypto/tls/handshake_client.go
+++ b/src/crypto/tls/handshake_client.go
@@ -714,17 +714,11 @@ func (hs *clientHandshakeState) processServerHello() (bool, error) {
                }
        }
 
-       if hs.serverHello.alpnProtocol != "" {
-               if len(hs.hello.alpnProtocols) == 0 {
-                       c.sendAlert(alertUnsupportedExtension)
-                       return false, errors.New("tls: server advertised unrequested ALPN extension")
-               }
-               if mutualProtocol([]string{hs.serverHello.alpnProtocol}, hs.hello.alpnProtocols) == "" {
-                       c.sendAlert(alertUnsupportedExtension)
-                       return false, errors.New("tls: server selected unadvertised ALPN protocol")
-               }
-               c.clientProtocol = hs.serverHello.alpnProtocol
+       if err := checkALPN(hs.hello.alpnProtocols, hs.serverHello.alpnProtocol); err != nil {
+               c.sendAlert(alertUnsupportedExtension)
+               return false, err
        }
+       c.clientProtocol = hs.serverHello.alpnProtocol
 
        c.scts = hs.serverHello.scts
 
@@ -756,6 +750,23 @@ func (hs *clientHandshakeState) processServerHello() (bool, error) {
        return true, nil
 }
 
+// checkALPN ensure that the server's choice of ALPN protocol is compatible with
+// the protocols that we advertised in the Client Hello.
+func checkALPN(clientProtos []string, serverProto string) error {
+       if serverProto == "" {
+               return nil
+       }
+       if len(clientProtos) == 0 {
+               return errors.New("tls: server advertised unrequested ALPN extension")
+       }
+       for _, proto := range clientProtos {
+               if proto == serverProto {
+                       return nil
+               }
+       }
+       return errors.New("tls: server selected unadvertised ALPN protocol")
+}
+
 func (hs *clientHandshakeState) readFinished(out []byte) error {
        c := hs.c
 
@@ -984,19 +995,6 @@ func clientSessionCacheKey(serverAddr net.Addr, config *Config) string {
        return serverAddr.String()
 }
 
-// mutualProtocol finds the mutual ALPN protocol given list of possible
-// protocols and a list of the preference order.
-func mutualProtocol(protos, preferenceProtos []string) string {
-       for _, s := range preferenceProtos {
-               for _, c := range protos {
-                       if s == c {
-                               return s
-                       }
-               }
-       }
-       return ""
-}
-
 // hostnameInSNI converts name into an appropriate hostname for SNI.
 // Literal IP addresses and absolute FQDNs are not permitted as SNI values.
 // See RFC 6066, Section 3.