crypto/tls: extend NPN support to the client.

R=bradfitzgo, rsc1, bradfitzwork
CC=golang-dev
https://golang.org/cl/4277085

diff --git a/src/pkg/crypto/tls/common.go b/src/pkg/crypto/tls/common.go
index 81b5a07446ea644b0e4cb5047fe8b23e343cdca4..c7792343942243b2614286521d41218e046897fe 100644 (file)
--- a/src/pkg/crypto/tls/common.go
+++ b/src/pkg/crypto/tls/common.go
@@ -93,9 +93,10 @@ const (
 
 // ConnectionState records basic TLS details about the connection.
 type ConnectionState struct {
-       HandshakeComplete  bool
-       CipherSuite        uint16
-       NegotiatedProtocol string
+       HandshakeComplete          bool
+       CipherSuite                uint16
+       NegotiatedProtocol         string
+       NegotiatedProtocolIsMutual bool
 
        // the certificate chain that was presented by the other side
        PeerCertificates []*x509.Certificate
@@ -124,7 +125,6 @@ type Config struct {
        RootCAs *CASet
 
        // NextProtos is a list of supported, application level protocols.
-       // Currently only server-side handling is supported.
        NextProtos []string
 
        // ServerName is included in the client's handshake to support virtual

diff --git a/src/pkg/crypto/tls/conn.go b/src/pkg/crypto/tls/conn.go
index 1e6fe60aec2a4ba630bce7f1967fa2ae81f975e9..b94e235c814fc7aea41c2131f2bb61a4cbd1066a 100644 (file)
--- a/src/pkg/crypto/tls/conn.go
+++ b/src/pkg/crypto/tls/conn.go
@@ -35,7 +35,8 @@ type Conn struct {
        ocspResponse      []byte // stapled OCSP response
        peerCertificates  []*x509.Certificate
 
-       clientProtocol string
+       clientProtocol         string
+       clientProtocolFallback bool
 
        // first permanent error
        errMutex sync.Mutex
@@ -761,6 +762,7 @@ func (c *Conn) ConnectionState() ConnectionState {
        state.HandshakeComplete = c.handshakeComplete
        if c.handshakeComplete {
                state.NegotiatedProtocol = c.clientProtocol
+               state.NegotiatedProtocolIsMutual = !c.clientProtocolFallback
                state.CipherSuite = c.cipherSuite
                state.PeerCertificates = c.peerCertificates
        }

diff --git a/src/pkg/crypto/tls/handshake_client.go b/src/pkg/crypto/tls/handshake_client.go
index a325a9b953cf9a0d011bc564dfee01667c0286ce..540b25c8753a7408df7adfa9fc35bee35b9dc088 100644 (file)
--- a/src/pkg/crypto/tls/handshake_client.go
+++ b/src/pkg/crypto/tls/handshake_client.go
@@ -29,6 +29,7 @@ func (c *Conn) clientHandshake() os.Error {
                serverName:         c.config.ServerName,
                supportedCurves:    []uint16{curveP256, curveP384, curveP521},
                supportedPoints:    []uint8{pointFormatUncompressed},
+               nextProtoNeg:       len(c.config.NextProtos) > 0,
        }
 
        t := uint32(c.config.time())
@@ -66,6 +67,11 @@ func (c *Conn) clientHandshake() os.Error {
                return c.sendAlert(alertUnexpectedMessage)
        }
 
+       if !hello.nextProtoNeg && serverHello.nextProtoNeg {
+               c.sendAlert(alertHandshakeFailure)
+               return os.ErrorString("server advertised unrequested NPN")
+       }
+
        suite, suiteId := mutualCipherSuite(c.config.cipherSuites(), serverHello.cipherSuite)
        if suite == nil {
                return c.sendAlert(alertHandshakeFailure)
@@ -267,6 +273,17 @@ func (c *Conn) clientHandshake() os.Error {
        c.out.prepareCipherSpec(clientCipher, clientHash)
        c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
 
+       if serverHello.nextProtoNeg {
+               nextProto := new(nextProtoMsg)
+               proto, fallback := mutualProtocol(c.config.NextProtos, serverHello.nextProtos)
+               nextProto.proto = proto
+               c.clientProtocol = proto
+               c.clientProtocolFallback = fallback
+
+               finishedHash.Write(nextProto.marshal())
+               c.writeRecord(recordTypeHandshake, nextProto.marshal())
+       }
+
        finished := new(finishedMsg)
        finished.verifyData = finishedHash.clientSum(masterSecret)
        finishedHash.Write(finished.marshal())
@@ -299,3 +316,19 @@ func (c *Conn) clientHandshake() os.Error {
        c.cipherSuite = suiteId
        return nil
 }
+
+// mutualProtocol finds the mutual Next Protocol Negotiation protocol given the
+// set of client and server supported protocols. The set of client supported
+// protocols must not be empty. It returns the resulting protocol and flag
+// indicating if the fallback case was reached.
+func mutualProtocol(clientProtos, serverProtos []string) (string, bool) {
+       for _, s := range serverProtos {
+               for _, c := range clientProtos {
+                       if s == c {
+                               return s, false
+                       }
+               }
+       }
+
+       return clientProtos[0], true
+}