Review comments #1.

clientconn.go

@@ -1272,12 +1272,6 @@ func (ac *addrConn) createTransport(addr resolver.Address, copts transport.Conne
 		copts.ChannelzParentID = ac.channelzID
 	}
 
-	// gRPC, resolver, balancer etc. can specify arbitrary data in the
-	// Attributes field of resolver.Address, which is shoved into connectCtx
-	// that is passed to the transport layer. The transport layer passes the
-	// same context to the credential handshaker. This makes is possible for
-	// address specific arbitrary data to reach the credential handshaker.
-	connectCtx = credentials.WithAddressInfo(connectCtx, credentials.AddressInfo{Attr: addr.Attributes})
 	newTr, err := transport.NewClientTransport(connectCtx, ac.cc.ctx, addr, copts, onPrefaceReceipt, onGoAway, onClose)
 	if err != nil {
 		// newTr is either nil, or closed.

credentials/credentials.go

@@ -194,30 +194,31 @@ func RequestInfoFromContext(ctx context.Context) (ri RequestInfo, ok bool) {
 	return
 }
 
-// AddressInfo contains address related data attached to the context passed to
-// ClientHandshake. This makes it possible to pass arbitrary data to the
-// handshaker from gRPC, resolver, balancer etc. Individual credential
-// implementations control the actual format of the data that they are willing
-// to receive.
+// ClientHandshakeInfo holds data to be passed to ClientHandshake. This makes
+// it possible to pass arbitrary data to the handshaker from gRPC, resolver,
+// balancer etc. Individual credential implementations control the actual
+// format of the data that they are willing to receive.
 //
 // This API is experimental.
-type AddressInfo struct {
+type ClientHandshakeInfo struct {
 	// Attr is a generic key/value store.
 	Attr *attributes.Attributes
 }
 
-// addressInfoKey is a struct used as the key to store AddressInfo in a context.
-type addressInfoKey struct{}
+// clientHandshakeInfoKey is a struct used as the key to store
+// ClientHandshakeInfo in a context.
+type clientHandshakeInfoKey struct{}
 
-// WithAddressInfo returns a copy of parent with ai stored as a value.
-func WithAddressInfo(parent context.Context, ai AddressInfo) context.Context {
-	return context.WithValue(parent, addressInfoKey{}, ai)
+// WithClientHandshakeInfo returns a copy of parent with chi stored as a value.
+func WithClientHandshakeInfo(parent context.Context, chi ClientHandshakeInfo) context.Context {
+	return context.WithValue(parent, clientHandshakeInfoKey{}, chi)
 }
 
-// AddressInfoFromContext returns the AddressInfo stored in ctx.
-func AddressInfoFromContext(ctx context.Context) AddressInfo {
-	ai, _ := ctx.Value(addressInfoKey{}).(AddressInfo)
-	return ai
+// ClientHandshakeInfoFromContext returns the ClientHandshakeInfo struct stored
+// in ctx.
+func ClientHandshakeInfoFromContext(ctx context.Context) ClientHandshakeInfo {
+	chi, _ := ctx.Value(clientHandshakeInfoKey{}).(ClientHandshakeInfo)
+	return chi
 }
 
 // CheckSecurityLevel checks if a connection's security level is greater than or equal to the specified one.

internal/transport/http2_client.go

@@ -215,6 +215,11 @@ func newHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 		}
 	}
 	if transportCreds != nil {
+		// gRPC, resolver, balancer etc. can specify arbitrary data in the
+		// Attributes field of resolver.Address, which is shoved into connectCtx
+		// and passed to the credential handshaker. This makes it possible for
+		// address specific arbitrary data to reach the credential handshaker.
+		connectCtx = credentials.WithClientHandshakeInfo(connectCtx, credentials.ClientHandshakeInfo{Attr: addr.Attributes})
 		scheme = "https"
 		conn, authInfo, err = transportCreds.ClientHandshake(connectCtx, addr.ServerName, conn)
 		if err != nil {

internal/transport/transport_test.go

@@ -34,9 +34,12 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/hpack"
+	"google.golang.org/grpc/attributes"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/internal/grpctest"
 	"google.golang.org/grpc/internal/leakcheck"
 	"google.golang.org/grpc/internal/testutils"
@@ -1816,3 +1819,54 @@ func (s) TestHeaderTblSize(t *testing.T) {
 		t.Fatalf("expected len(limits) = 2 within 10s, got != 2")
 	}
 }
+
+// attrTransportCreds is a transport credential implementation which stores
+// Attributes from the ClientHandshakeInfo struct passed in the context locally
+// for the test to inspect.
+type attrTransportCreds struct {
+	credentials.TransportCredentials
+	attr *attributes.Attributes
+}
+
+func (ac *attrTransportCreds) ClientHandshake(ctx context.Context, addr string, rawConn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	ai := credentials.ClientHandshakeInfoFromContext(ctx)
+	ac.attr = ai.Attr
+	return rawConn, nil, nil
+}
+func (ac *attrTransportCreds) Info() credentials.ProtocolInfo {
+	return credentials.ProtocolInfo{}
+}
+func (ac *attrTransportCreds) Clone() credentials.TransportCredentials {
+	return nil
+}
+
+// TestClientHandshakeInfo adds attributes to the resolver.Address passes to
+// NewClientTransport and verifies that these attributes are received by the
+// transport credential handshaker.
+func (s) TestClientHandshakeInfo(t *testing.T) {
+	server := setUpServerOnly(t, 0, &ServerConfig{}, pingpong)
+	defer server.stop()
+
+	const (
+		testAttrKey = "foo"
+		testAttrVal = "bar"
+	)
+	addr := resolver.Address{
+		Addr:       "localhost:" + server.port,
+		Attributes: attributes.New(testAttrKey, testAttrVal),
+	}
+	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(2*time.Second))
+	defer cancel()
+	creds := &attrTransportCreds{}
+
+	tr, err := NewClientTransport(ctx, context.Background(), addr, ConnectOptions{TransportCredentials: creds}, func() {}, func(GoAwayReason) {}, func() {})
+	if err != nil {
+		t.Fatalf("NewClientTransport(): %v", err)
+	}
+	defer tr.Close()
+
+	wantAttr := attributes.New(testAttrKey, testAttrVal)
+	if gotAttr := creds.attr; !cmp.Equal(gotAttr, wantAttr, cmp.AllowUnexported(attributes.Attributes{})) {
+		t.Fatalf("received attributes %v in creds, want %v", gotAttr, wantAttr)
+	}
+}

test/balancer_test.go

@@ -353,27 +353,27 @@ func (s) TestNonGRPCLBBalancerGetsNoGRPCLBAddress(t *testing.T) {
 	}
 }
 
-const aiBalancerName = "addrInfo-attribute-balancer"
+const attrBalancerName = "attribute-balancer"
 
-// aiBalancerBuilder builds a balancer and passes the attribute key and value
+// attrBalancerBuilder builds a balancer and passes the attribute key and value
 // with which it was configured at creation time by the test.
-type aiBalancerBuilder struct {
+type attrBalancerBuilder struct {
 	attrKey string
 	attrVal string
 }
 
-func (bb *aiBalancerBuilder) Build(cc balancer.ClientConn, opts balancer.BuildOptions) balancer.Balancer {
-	return &aiBalancer{cc: cc, attrKey: bb.attrKey, attrVal: bb.attrVal}
+func (bb *attrBalancerBuilder) Build(cc balancer.ClientConn, opts balancer.BuildOptions) balancer.Balancer {
+	return &attrBalancer{cc: cc, attrKey: bb.attrKey, attrVal: bb.attrVal}
 }
 
-func (bb *aiBalancerBuilder) Name() string {
-	return aiBalancerName
+func (bb *attrBalancerBuilder) Name() string {
+	return attrBalancerName
 }
 
-// aiBalancer receives an attribute key and value which it adds to the address
-// that it calls NewSubConn on. This key/value pair reaches the credential
-// handshaker and the test verifies the same.
-type aiBalancer struct {
+// attrBalancer receives an attribute key and value which it adds to the
+// address that it calls NewSubConn on. This key/value pair reaches the
+// credential handshaker and the test verifies the same.
+type attrBalancer struct {
 	balancer.Balancer
 	cc      balancer.ClientConn
 	attrKey string
@@ -382,7 +382,7 @@ type aiBalancer struct {
 
 // UpdateClientConnState adds an attribute with the configured key/value to the
 // addresses received and invokes NewSubConn.
-func (b *aiBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error {
+func (b *attrBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error {
 	addrs := ccs.ResolverState.Addresses
 	if len(addrs) == 0 {
 		return nil
@@ -399,12 +399,12 @@ func (b *aiBalancer) UpdateClientConnState(ccs balancer.ClientConnState) error {
 	return nil
 }
 
-func (b *aiBalancer) UpdateSubConnState(sc balancer.SubConn, state balancer.SubConnState) {
+func (b *attrBalancer) UpdateSubConnState(sc balancer.SubConn, state balancer.SubConnState) {
 	b.cc.UpdateState(balancer.State{ConnectivityState: state.ConnectivityState, Picker: &aiPicker{result: balancer.PickResult{SubConn: sc}, err: state.ConnectionError}})
 }
 
-func (b *aiBalancer) ResolverError(error) {}
-func (b *aiBalancer) Close()              {}
+func (b *attrBalancer) ResolverError(error) {}
+func (b *attrBalancer) Close()              {}
 
 type aiPicker struct {
 	result balancer.PickResult
@@ -415,22 +415,23 @@ func (aip *aiPicker) Pick(_ balancer.PickInfo) (balancer.PickResult, error) {
 	return aip.result, aip.err
 }
 
-// addrInfoTransportCreds is a transport credential implementation which stores
-// the Attributes struct passed in the context locally for the test to inspect.
-type addrInfoTransportCreds struct {
+// attrTransportCreds is a transport credential implementation which stores
+// Attributes from the ClientHandshakeInfo struct passed in the context locally
+// for the test to inspect.
+type attrTransportCreds struct {
 	credentials.TransportCredentials
 	attr *attributes.Attributes
 }
 
-func (ac *addrInfoTransportCreds) ClientHandshake(ctx context.Context, addr string, rawConn net.Conn) (net.Conn, credentials.AuthInfo, error) {
-	ai := credentials.AddressInfoFromContext(ctx)
+func (ac *attrTransportCreds) ClientHandshake(ctx context.Context, addr string, rawConn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	ai := credentials.ClientHandshakeInfoFromContext(ctx)
 	ac.attr = ai.Attr
 	return rawConn, nil, nil
 }
-func (ac *addrInfoTransportCreds) Info() credentials.ProtocolInfo {
+func (ac *attrTransportCreds) Info() credentials.ProtocolInfo {
 	return credentials.ProtocolInfo{}
 }
-func (ac *addrInfoTransportCreds) Clone() credentials.TransportCredentials {
+func (ac *attrTransportCreds) Clone() credentials.TransportCredentials {
 	return nil
 }
 
@@ -444,9 +445,9 @@ func (s) TestAddressAttributesInNewSubConn(t *testing.T) {
 		testAttrVal = "bar"
 	)
 
-	balancer.Register(&aiBalancerBuilder{attrKey: testAttrKey, attrVal: testAttrVal})
-	defer internal.BalancerUnregister(aiBalancerName)
-	t.Logf("Registered balancer %s...", aiBalancerName)
+	balancer.Register(&attrBalancerBuilder{attrKey: testAttrKey, attrVal: testAttrVal})
+	defer internal.BalancerUnregister(attrBalancerName)
+	t.Logf("Registered balancer %s...", attrBalancerName)
 
 	r, cleanup := manual.GenerateAndRegisterManualResolver()
 	defer cleanup()
@@ -463,10 +464,10 @@ func (s) TestAddressAttributesInNewSubConn(t *testing.T) {
 	defer s.Stop()
 	t.Logf("Started gRPC server at %s...", lis.Addr().String())
 
-	creds := &addrInfoTransportCreds{}
+	creds := &attrTransportCreds{}
 	dopts := []grpc.DialOption{
 		grpc.WithTransportCredentials(creds),
-		grpc.WithDefaultServiceConfig(fmt.Sprintf(`{ "loadBalancingConfig": [{"%v": {}}] }`, aiBalancerName)),
+		grpc.WithDefaultServiceConfig(fmt.Sprintf(`{ "loadBalancingConfig": [{"%v": {}}] }`, attrBalancerName)),
 	}
 	cc, err := grpc.Dial(r.Scheme()+":///test.server", dopts...)
 	if err != nil {