snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

experimental/balancer/hostname/hostname.go

@@ -0,0 +1,47 @@
+/*
+ *
+ * Copyright 2026 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package hostname contains utilities for the endpoint hostname attribute
+// (used for per-endpoint :authority / SNI override).
+//
+// # Experimental
+//
+// Notice: All APIs in this package are EXPERIMENTAL and may be changed
+// or removed in a later release.
+package hostname
+
+import "google.golang.org/grpc/resolver"
+
+type hostnameKey struct{}
+
+// Set returns a copy of the given endpoint with the hostname attribute
+// set. If hostname is empty the endpoint is returned unmodified.
+func Set(endpoint resolver.Endpoint, hostname string) resolver.Endpoint {
+	if hostname == "" {
+		return endpoint
+	}
+	endpoint.Attributes = endpoint.Attributes.WithValue(hostnameKey{}, hostname)
+	return endpoint
+}
+
+// FromEndpoint returns the hostname attribute of endpoint. If this
+// attribute is not set, it returns the empty string.
+func FromEndpoint(endpoint resolver.Endpoint) string {
+	h, _ := endpoint.Attributes.Value(hostnameKey{}).(string)
+	return h
+}

experimental/balancer/hostname/hostname_test.go

@@ -0,0 +1,75 @@
+/*
+ *
+ * Copyright 2026 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package hostname_test
+
+import (
+	"testing"
+
+	"google.golang.org/grpc/attributes"
+	"google.golang.org/grpc/experimental/balancer/hostname"
+	"google.golang.org/grpc/internal/grpctest"
+	"google.golang.org/grpc/resolver"
+)
+
+type s struct {
+	grpctest.Tester
+}
+
+func Test(t *testing.T) {
+	grpctest.RunSubTests(t, s{})
+}
+
+func (s) TestHostnameToAndFromEndpoint(t *testing.T) {
+	tests := []struct {
+		desc            string
+		inputHostname   string
+		inputAttributes *attributes.Attributes
+		wantHostname    string
+	}{
+		{
+			desc:          "empty_attributes",
+			inputHostname: "myservice.example.com",
+			wantHostname:  "myservice.example.com",
+		},
+		{
+			desc:            "non-empty_attributes",
+			inputHostname:   "myservice.example.com",
+			inputAttributes: attributes.New("foo", "bar"),
+			wantHostname:    "myservice.example.com",
+		},
+		{
+			desc: "hostname_not_present_in_empty_attributes",
+		},
+		{
+			desc:            "hostname_not_present_in_non-empty_attributes",
+			inputAttributes: attributes.New("foo", "bar"),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			endpoint := resolver.Endpoint{Attributes: test.inputAttributes}
+			endpoint = hostname.Set(endpoint, test.inputHostname)
+			gotHostname := hostname.FromEndpoint(endpoint)
+			if gotHostname != test.wantHostname {
+				t.Errorf("hostname.FromEndpoint(%+v) = %q, want %q", endpoint, gotHostname, test.wantHostname)
+			}
+		})
+	}
+}