metadata: fix validation issues

internal/metadata/metadata.go

@@ -82,14 +82,13 @@ func Set(addr resolver.Address, md metadata.MD) resolver.Address {
 // - header names must contain one or more characters from this set [0-9 a-z _ - .].
 // - if the header-name ends with a "-bin" suffix, no validation of the header value is performed.
 // - otherwise, the header value must contain one or more characters from the set [%x20-%x7E].
-func Validate(md metadata.MD) (err error) {
+func Validate(md metadata.MD) error {
 	for k, vals := range md {
-		err = ValidatePair(k, vals...)
-		if err != nil {
-			break
+		if err := ValidatePair(k, vals...); err != nil {
+			return err
 		}
 	}
-	return
+	return nil
 }
 
 // hasNotPrintable return true if msg contains any characters which are not in %x20-%x7E

internal/metadata/metadata_test.go

@@ -101,7 +101,7 @@ func TestValidate(t *testing.T) {
 			want: errors.New("header key \"test\" contains value with non-printable ASCII characters"),
 		},
 		{
-			md:   map[string][]string{"": {string(rune(0x19))}},
+			md:   map[string][]string{"": {"valid"}},
 			want: errors.New("there is an empty key in the header"),
 		},
 		{

stream.go

@@ -170,15 +170,13 @@ func NewClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, meth
 func newClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (_ ClientStream, err error) {
 	if md, added, ok := metadata.FromOutgoingContextRaw(ctx); ok {
 		// validate md
-		err := imetadata.Validate(md)
-		if err != nil {
+		if err := imetadata.Validate(md); err != nil {
 			return nil, status.Error(codes.Internal, err.Error())
 		}
 		// validate added
 		for _, kvs := range added {
 			for i := 0; i < len(kvs); i += 2 {
-				err = imetadata.ValidatePair(kvs[i], kvs[i+1])
-				if err != nil {
+				if err = imetadata.ValidatePair(kvs[i], kvs[i+1]); err != nil {
 					return nil, status.Error(codes.Internal, err.Error())
 				}
 			}

test/metadata_test.go

@@ -103,8 +103,8 @@ func (s) TestInvalidMetadata(t *testing.T) {
 			}
 			test := tests[testNum]
 			testNum++
-			// merge original md and added md
-			md := test.md.Copy()
+			// merge original md and added md.
+			md := metadata.Join(test.md, metadata.Pairs(test.appendMD...))
 			for i := 0; i < len(test.appendMD); i += 2 {
 				md.Append(test.appendMD[i], test.appendMD[i+1])
 			}