net/http: minor fixes and optimization for Response.TLS

Also add it to doc/go1.3.txt.

Update #7289

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/71740043

doc/go1.3.txt

@@ -8,6 +8,7 @@ crypto/x509: support CSRs (CL 49830048)
 liblink: pull linker i/o into separate liblink C library (CL 35790044)
 misc/benchcmp: removed and replaced by go.tools/cmd/benchcmp (CL 47980043)
 misc/dist: renamed misc/makerelease (CL 39920043)
+net/http: add Request.TLS (CL 52660047)
 net/http: add Server.ErrorLog; log and test TLS handshake errors (CL 70250044)
 net/http: add Server.SetKeepAlivesEnabled (CL 69670043)
 net/http: add Transport.TLSHandshakeTimeout; set it by default (CL 68150045)

src/pkg/net/http/client_test.go

@@ -727,14 +727,13 @@ func TestResponseSetsTLSConnectionState(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer res.Body.Close()
 	if res.TLS == nil {
 		t.Fatal("Response didn't set TLS Connection State.")
 	}
-	if res.TLS.CipherSuite != tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA {
-		t.Errorf("Unexpected TLS Cipher Suite: %d != %d",
-			res.TLS.CipherSuite, tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA)
+	if got, want := res.TLS.CipherSuite, tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA; got != want {
+		t.Errorf("TLS Cipher Suite = %d; want %d", got, want)
 	}
-	res.Body.Close()
 }
 
 // Verify Response.ContentLength is populated. http://golang.org/issue/4126

src/pkg/net/http/response.go

@@ -76,10 +76,10 @@ type Response struct {
 	// This is only populated for Client requests.
 	Request *Request
 
-	// TLS allows information about the TLS connection on which the
-	// response was received. The Transport in this package sets the field
-	// for TLS-enabled connections before returning the Response otherwise
-	// it leaves the field nil.
+	// TLS contains information about the TLS connection on which the
+	// response was received. It is nil for unencrypted responses.
+	// The pointer is shared between responses and should not be
+	// modified.
 	TLS *tls.ConnectionState
 }
 

src/pkg/net/http/transport.go

@@ -583,6 +583,8 @@ func (t *Transport) dialConn(cm connectMethod) (*persistConn, error) {
 				return nil, err
 			}
 		}
+		cs := tlsConn.ConnectionState()
+		pconn.tlsState = &cs
 		pconn.conn = tlsConn
 	}
 
@@ -718,6 +720,7 @@ type persistConn struct {
 	t        *Transport
 	cacheKey connectMethodKey
 	conn     net.Conn
+	tlsState *tls.ConnectionState
 	closed   bool                // whether conn has been closed
 	br       *bufio.Reader       // from conn
 	bw       *bufio.Writer       // to conn
@@ -792,9 +795,8 @@ func (pc *persistConn) readLoop() {
 			}
 		}
 
-		if tlsConn, ok := pc.conn.(*tls.Conn); resp != nil && ok {
-			resp.TLS = new(tls.ConnectionState)
-			*resp.TLS = tlsConn.ConnectionState()
+		if resp != nil {
+			resp.TLS = pc.tlsState
 		}
 
 		hasBody := resp != nil && rc.req.Method != "HEAD" && resp.ContentLength != 0