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

balancer/rls/internal/keys/builder.go

@@ -0,0 +1,267 @@
+/*
+ *
+ * Copyright 2020 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 keys provides functionality required to build RLS request keys.
+package keys
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+
+	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
+	"google.golang.org/grpc/metadata"
+)
+
+// BuilderMap maps from request path to the key builder for that path.
+type BuilderMap map[string]builder
+
+// MakeBuilderMap parses the provided RouteLookupConfig proto and returns a map
+// from paths to key builders.
+func MakeBuilderMap(cfg *rlspb.RouteLookupConfig) (BuilderMap, error) {
+	kbs := cfg.GetGrpcKeybuilders()
+	if len(kbs) == 0 {
+		return nil, errors.New("rls: RouteLookupConfig does not contain any GrpcKeyBuilder")
+	}
+
+	bm := make(map[string]builder)
+	for _, kb := range kbs {
+		// Extract keys from `headers`, `constant_keys` and `extra_keys` fields
+		// and populate appropriate values in the builder struct. Also ensure
+		// that keys are not repeated.
+		var matchers []matcher
+		seenKeys := make(map[string]bool)
+		constantKeys := kb.GetConstantKeys()
+		for k := range kb.GetConstantKeys() {
+			seenKeys[k] = true
+		}
+		for _, h := range kb.GetHeaders() {
+			if h.GetRequiredMatch() {
+				return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig has required_match field set {%+v}", kbs)
+			}
+			key := h.GetKey()
+			if seenKeys[key] {
+				return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key %q across headers, constant_keys and extra_keys {%+v}", key, kbs)
+			}
+			seenKeys[key] = true
+			matchers = append(matchers, matcher{key: h.GetKey(), names: h.GetNames()})
+		}
+		if seenKeys[kb.GetExtraKeys().GetHost()] {
+			return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key %q in extra_keys from constant_keys or headers {%+v}", kb.GetExtraKeys().GetHost(), kbs)
+		}
+		if seenKeys[kb.GetExtraKeys().GetService()] {
+			return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key %q in extra_keys from constant_keys or headers {%+v}", kb.GetExtraKeys().GetService(), kbs)
+		}
+		if seenKeys[kb.GetExtraKeys().GetMethod()] {
+			return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key %q in extra_keys from constant_keys or headers {%+v}", kb.GetExtraKeys().GetMethod(), kbs)
+		}
+		b := builder{
+			headerKeys:   matchers,
+			constantKeys: constantKeys,
+			hostKey:      kb.GetExtraKeys().GetHost(),
+			serviceKey:   kb.GetExtraKeys().GetService(),
+			methodKey:    kb.GetExtraKeys().GetMethod(),
+		}
+
+		// Store the builder created above in the BuilderMap based on the value
+		// of the `Names` field, which wraps incoming request's service and
+		// method. Also, ensure that there are no repeated `Names` field.
+		names := kb.GetNames()
+		if len(names) == 0 {
+			return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig does not contain any Name {%+v}", kbs)
+		}
+		for _, name := range names {
+			if name.GetService() == "" {
+				return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains a Name field with no Service {%+v}", kbs)
+			}
+			if strings.Contains(name.GetMethod(), `/`) {
+				return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains a method with a slash {%+v}", kbs)
+			}
+			path := "/" + name.GetService() + "/" + name.GetMethod()
+			if _, ok := bm[path]; ok {
+				return nil, fmt.Errorf("rls: GrpcKeyBuilder in RouteLookupConfig contains repeated Name field {%+v}", kbs)
+			}
+			bm[path] = b
+		}
+	}
+	return bm, nil
+}
+
+// KeyMap represents the RLS keys to be used for a request.
+type KeyMap struct {
+	// Map is the representation of an RLS key as a Go map. This is used when
+	// an actual RLS request is to be sent out on the wire, since the
+	// RouteLookupRequest proto expects a Go map.
+	Map map[string]string
+	// Str is the representation of an RLS key as a string, sorted by keys.
+	// Since the RLS keys are part of the cache key in the request cache
+	// maintained by the RLS balancer, and Go maps cannot be used as keys for
+	// Go maps (the cache is implemented as a map), we need a stringified
+	// version of it.
+	Str string
+}
+
+// RLSKey builds the RLS keys to be used for the given request, identified by
+// the request path and the request headers stored in metadata.
+func (bm BuilderMap) RLSKey(md metadata.MD, host, path string) KeyMap {
+	// The path passed in is of the form "/service/method". The keyBuilderMap is
+	// indexed with keys of the form "/service/" or "/service/method". The service
+	// that we set in the keyMap (to be sent out in the RLS request) should not
+	// include any slashes though.
+	i := strings.LastIndex(path, "/")
+	service, method := path[:i+1], path[i+1:]
+	b, ok := bm[path]
+	if !ok {
+		b, ok = bm[service]
+		if !ok {
+			return KeyMap{}
+		}
+	}
+
+	kvMap := b.buildHeaderKeys(md)
+	if b.hostKey != "" {
+		kvMap[b.hostKey] = host
+	}
+	if b.serviceKey != "" {
+		kvMap[b.serviceKey] = strings.Trim(service, "/")
+	}
+	if b.methodKey != "" {
+		kvMap[b.methodKey] = method
+	}
+	for k, v := range b.constantKeys {
+		kvMap[k] = v
+	}
+	return KeyMap{Map: kvMap, Str: mapToString(kvMap)}
+}
+
+// Equal reports whether bm and am represent equivalent BuilderMaps.
+func (bm BuilderMap) Equal(am BuilderMap) bool {
+	if (bm == nil) != (am == nil) {
+		return false
+	}
+	if len(bm) != len(am) {
+		return false
+	}
+
+	for key, bBuilder := range bm {
+		aBuilder, ok := am[key]
+		if !ok {
+			return false
+		}
+		if !bBuilder.Equal(aBuilder) {
+			return false
+		}
+	}
+	return true
+}
+
+// builder provides the actual functionality of building RLS keys.
+type builder struct {
+	headerKeys   []matcher
+	constantKeys map[string]string
+	// The following keys mirror corresponding fields in `extra_keys`.
+	hostKey    string
+	serviceKey string
+	methodKey  string
+}
+
+// Equal reports whether b and a represent equivalent key builders.
+func (b builder) Equal(a builder) bool {
+	if len(b.headerKeys) != len(a.headerKeys) {
+		return false
+	}
+	// Protobuf serialization maintains the order of repeated fields. Matchers
+	// are specified as a repeated field inside the KeyBuilder proto. If the
+	// order changes, it means that the order in the protobuf changed. We report
+	// this case as not being equal even though the builders could possibly be
+	// functionally equal.
+	for i, bMatcher := range b.headerKeys {
+		aMatcher := a.headerKeys[i]
+		if !bMatcher.Equal(aMatcher) {
+			return false
+		}
+	}
+
+	if len(b.constantKeys) != len(a.constantKeys) {
+		return false
+	}
+	for k, v := range b.constantKeys {
+		if a.constantKeys[k] != v {
+			return false
+		}
+	}
+
+	return b.hostKey == a.hostKey && b.serviceKey == a.serviceKey && b.methodKey == a.methodKey
+}
+
+// matcher helps extract a key from request headers based on a given name.
+type matcher struct {
+	// The key used in the keyMap sent as part of the RLS request.
+	key string
+	// List of header names which can supply the value for this key.
+	names []string
+}
+
+// Equal reports if m and a are equivalent headerKeys.
+func (m matcher) Equal(a matcher) bool {
+	if m.key != a.key {
+		return false
+	}
+	if len(m.names) != len(a.names) {
+		return false
+	}
+	for i := 0; i < len(m.names); i++ {
+		if m.names[i] != a.names[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func (b builder) buildHeaderKeys(md metadata.MD) map[string]string {
+	kvMap := make(map[string]string)
+	if len(md) == 0 {
+		return kvMap
+	}
+	for _, m := range b.headerKeys {
+		for _, name := range m.names {
+			if vals := md.Get(name); vals != nil {
+				kvMap[m.key] = strings.Join(vals, ",")
+				break
+			}
+		}
+	}
+	return kvMap
+}
+
+func mapToString(kv map[string]string) string {
+	keys := make([]string, 0, len(kv))
+	for k := range kv {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	var sb strings.Builder
+	for i, k := range keys {
+		if i != 0 {
+			fmt.Fprint(&sb, ",")
+		}
+		fmt.Fprintf(&sb, "%s=%s", k, kv[k])
+	}
+	return sb.String()
+}

balancer/rls/internal/keys/builder_test.go

@@ -0,0 +1,650 @@
+/*
+ *
+ * Copyright 2020 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 keys
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	rlspb "google.golang.org/grpc/internal/proto/grpc_lookup_v1"
+	"google.golang.org/grpc/metadata"
+)
+
+var (
+	goodKeyBuilder1 = &rlspb.GrpcKeyBuilder{
+		Names: []*rlspb.GrpcKeyBuilder_Name{
+			{Service: "gFoo"},
+		},
+		Headers: []*rlspb.NameMatcher{
+			{Key: "k1", Names: []string{"n1"}},
+			{Key: "k2", Names: []string{"n1"}},
+		},
+		ExtraKeys: &rlspb.GrpcKeyBuilder_ExtraKeys{
+			Host:    "host",
+			Service: "service",
+			Method:  "method",
+		},
+		ConstantKeys: map[string]string{
+			"const-key-1": "const-val-1",
+			"const-key-2": "const-val-2",
+		},
+	}
+	goodKeyBuilder2 = &rlspb.GrpcKeyBuilder{
+		Names: []*rlspb.GrpcKeyBuilder_Name{
+			{Service: "gBar", Method: "method1"},
+			{Service: "gFoobar"},
+		},
+		Headers: []*rlspb.NameMatcher{
+			{Key: "k1", Names: []string{"n1", "n2"}},
+		},
+	}
+)
+
+func TestMakeBuilderMap(t *testing.T) {
+	gFooBuilder := builder{
+		headerKeys: []matcher{{key: "k1", names: []string{"n1"}}, {key: "k2", names: []string{"n1"}}},
+		constantKeys: map[string]string{
+			"const-key-1": "const-val-1",
+			"const-key-2": "const-val-2",
+		},
+		hostKey:    "host",
+		serviceKey: "service",
+		methodKey:  "method",
+	}
+	wantBuilderMap1 := map[string]builder{"/gFoo/": gFooBuilder}
+	wantBuilderMap2 := map[string]builder{
+		"/gFoo/":        gFooBuilder,
+		"/gBar/method1": {headerKeys: []matcher{{key: "k1", names: []string{"n1", "n2"}}}},
+		"/gFoobar/":     {headerKeys: []matcher{{key: "k1", names: []string{"n1", "n2"}}}},
+	}
+
+	tests := []struct {
+		desc           string
+		cfg            *rlspb.RouteLookupConfig
+		wantBuilderMap BuilderMap
+	}{
+		{
+			desc: "One good GrpcKeyBuilder",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{goodKeyBuilder1},
+			},
+			wantBuilderMap: wantBuilderMap1,
+		},
+		{
+			desc: "Two good GrpcKeyBuilders",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{goodKeyBuilder1, goodKeyBuilder2},
+			},
+			wantBuilderMap: wantBuilderMap2,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			builderMap, err := MakeBuilderMap(test.cfg)
+			if err != nil || !builderMap.Equal(test.wantBuilderMap) {
+				t.Errorf("MakeBuilderMap(%+v) returned {%v, %v}, want: {%v, nil}", test.cfg, builderMap, err, test.wantBuilderMap)
+			}
+		})
+	}
+}
+
+func TestMakeBuilderMapErrors(t *testing.T) {
+	tests := []struct {
+		desc          string
+		cfg           *rlspb.RouteLookupConfig
+		wantErrPrefix string
+	}{
+		{
+			desc:          "No GrpcKeyBuilder",
+			cfg:           &rlspb.RouteLookupConfig{},
+			wantErrPrefix: "rls: RouteLookupConfig does not contain any GrpcKeyBuilder",
+		},
+		{
+			desc: "Two GrpcKeyBuilders with same Name",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{goodKeyBuilder1, goodKeyBuilder1},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains repeated Name field",
+		},
+		{
+			desc: "GrpcKeyBuilder with empty Service field",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names: []*rlspb.GrpcKeyBuilder_Name{
+							{Service: "bFoo", Method: "method1"},
+							{Service: "bBar"},
+							{Method: "method1"},
+						},
+						Headers: []*rlspb.NameMatcher{{Key: "k1", Names: []string{"n1", "n2"}}},
+					},
+					goodKeyBuilder1,
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains a Name field with no Service",
+		},
+		{
+			desc: "GrpcKeyBuilder with no Name",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{{}, goodKeyBuilder1},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig does not contain any Name",
+		},
+		{
+			desc: "GrpcKeyBuilder with requiredMatch field set",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names:   []*rlspb.GrpcKeyBuilder_Name{{Service: "bFoo", Method: "method1"}},
+						Headers: []*rlspb.NameMatcher{{Key: "k1", Names: []string{"n1", "n2"}, RequiredMatch: true}},
+					},
+					goodKeyBuilder1,
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig has required_match field set",
+		},
+		{
+			desc: "GrpcKeyBuilder two headers with same key",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names: []*rlspb.GrpcKeyBuilder_Name{
+							{Service: "gBar", Method: "method1"},
+							{Service: "gFoobar"},
+						},
+						Headers: []*rlspb.NameMatcher{
+							{Key: "k1", Names: []string{"n1", "n2"}},
+							{Key: "k1", Names: []string{"n1", "n2"}},
+						},
+					},
+					goodKeyBuilder1,
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key \"k1\" across headers, constant_keys and extra_keys",
+		},
+		{
+			desc: "GrpcKeyBuilder repeated keys across headers and constant_keys",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names: []*rlspb.GrpcKeyBuilder_Name{
+							{Service: "gBar", Method: "method1"},
+							{Service: "gFoobar"},
+						},
+						Headers:      []*rlspb.NameMatcher{{Key: "k1", Names: []string{"n1", "n2"}}},
+						ConstantKeys: map[string]string{"k1": "v1"},
+					},
+					goodKeyBuilder1,
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key \"k1\" across headers, constant_keys and extra_keys",
+		},
+		{
+			desc: "GrpcKeyBuilder repeated keys across headers and extra_keys",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names: []*rlspb.GrpcKeyBuilder_Name{
+							{Service: "gBar", Method: "method1"},
+							{Service: "gFoobar"},
+						},
+						Headers:   []*rlspb.NameMatcher{{Key: "k1", Names: []string{"n1", "n2"}}},
+						ExtraKeys: &rlspb.GrpcKeyBuilder_ExtraKeys{Method: "k1"},
+					},
+					goodKeyBuilder1,
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key \"k1\" in extra_keys from constant_keys or headers",
+		},
+		{
+			desc: "GrpcKeyBuilder repeated keys across constant_keys and extra_keys",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names: []*rlspb.GrpcKeyBuilder_Name{
+							{Service: "gBar", Method: "method1"},
+							{Service: "gFoobar"},
+						},
+						Headers:      []*rlspb.NameMatcher{{Key: "k1", Names: []string{"n1", "n2"}}},
+						ConstantKeys: map[string]string{"host": "v1"},
+						ExtraKeys:    &rlspb.GrpcKeyBuilder_ExtraKeys{Host: "host"},
+					},
+					goodKeyBuilder1,
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains repeated key \"host\" in extra_keys from constant_keys or headers",
+		},
+		{
+			desc: "GrpcKeyBuilder with slash in method name",
+			cfg: &rlspb.RouteLookupConfig{
+				GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{
+					{
+						Names:   []*rlspb.GrpcKeyBuilder_Name{{Service: "gBar", Method: "method1/foo"}},
+						Headers: []*rlspb.NameMatcher{{Key: "k1", Names: []string{"n1", "n2"}}},
+					},
+				},
+			},
+			wantErrPrefix: "rls: GrpcKeyBuilder in RouteLookupConfig contains a method with a slash",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			builderMap, err := MakeBuilderMap(test.cfg)
+			if builderMap != nil || !strings.HasPrefix(fmt.Sprint(err), test.wantErrPrefix) {
+				t.Errorf("MakeBuilderMap(%+v) returned {%v, %v}, want: {nil, %v}", test.cfg, builderMap, err, test.wantErrPrefix)
+			}
+		})
+	}
+}
+
+func TestRLSKey(t *testing.T) {
+	bm, err := MakeBuilderMap(&rlspb.RouteLookupConfig{
+		GrpcKeybuilders: []*rlspb.GrpcKeyBuilder{goodKeyBuilder1, goodKeyBuilder2},
+	})
+	if err != nil {
+		t.Fatalf("MakeBuilderMap() failed: %v", err)
+	}
+
+	tests := []struct {
+		desc   string
+		path   string
+		md     metadata.MD
+		wantKM KeyMap
+	}{
+		{
+			// No keyBuilder is found for the provided service.
+			desc:   "service not found in key builder map",
+			path:   "/notFoundService/method",
+			md:     metadata.Pairs("n1", "v1", "n2", "v2"),
+			wantKM: KeyMap{},
+		},
+		{
+			// No keyBuilder is found for the provided method.
+			desc:   "method not found in key builder map",
+			path:   "/gBar/notFoundMethod",
+			md:     metadata.Pairs("n1", "v1", "n2", "v2"),
+			wantKM: KeyMap{},
+		},
+		{
+			// A keyBuilder is found, but none of the headers match.
+			desc:   "directPathMatch-NoMatchingKey",
+			path:   "/gBar/method1",
+			md:     metadata.Pairs("notMatchingKey", "v1"),
+			wantKM: KeyMap{Map: map[string]string{}, Str: ""},
+		},
+		{
+			// A keyBuilder is found, and a single headers matches.
+			desc:   "directPathMatch-SingleKey",
+			path:   "/gBar/method1",
+			md:     metadata.Pairs("n1", "v1"),
+			wantKM: KeyMap{Map: map[string]string{"k1": "v1"}, Str: "k1=v1"},
+		},
+		{
+			// A keyBuilder is found, and multiple headers match, but the first
+			// match is chosen.
+			desc:   "directPathMatch-FirstMatchingKey",
+			path:   "/gBar/method1",
+			md:     metadata.Pairs("n2", "v2", "n1", "v1"),
+			wantKM: KeyMap{Map: map[string]string{"k1": "v1"}, Str: "k1=v1"},
+		},
+		{
+			// A keyBuilder is found as a wildcard match, but none of the
+			// headers match.
+			desc:   "wildcardPathMatch-NoMatchingKey",
+			path:   "/gFoobar/method1",
+			md:     metadata.Pairs("notMatchingKey", "v1"),
+			wantKM: KeyMap{Map: map[string]string{}, Str: ""},
+		},
+		{
+			// A keyBuilder is found as a wildcard match, and a single headers
+			// matches.
+			desc:   "wildcardPathMatch-SingleKey",
+			path:   "/gFoobar/method1",
+			md:     metadata.Pairs("n1", "v1"),
+			wantKM: KeyMap{Map: map[string]string{"k1": "v1"}, Str: "k1=v1"},
+		},
+		{
+			// A keyBuilder is found as a wildcard match, and multiple headers
+			// match, but the first match is chosen.
+			desc:   "wildcardPathMatch-FirstMatchingKey",
+			path:   "/gFoobar/method1",
+			md:     metadata.Pairs("n2", "v2", "n1", "v1"),
+			wantKM: KeyMap{Map: map[string]string{"k1": "v1"}, Str: "k1=v1"},
+		},
+		{
+			// Multiple headerKeys find hits in the provided request headers.
+			desc: "multipleMatchers",
+			path: "/gFoo/method1",
+			md:   metadata.Pairs("n2", "v2", "n1", "v1"),
+			wantKM: KeyMap{
+				Map: map[string]string{
+					"const-key-1": "const-val-1",
+					"const-key-2": "const-val-2",
+					"host":        "dummy-host",
+					"service":     "gFoo",
+					"method":      "method1",
+					"k1":          "v1",
+					"k2":          "v1",
+				},
+				Str: "const-key-1=const-val-1,const-key-2=const-val-2,host=dummy-host,k1=v1,k2=v1,method=method1,service=gFoo",
+			},
+		},
+		{
+			// A match is found for a header which is specified multiple times.
+			// So, the values are joined with commas separating them.
+			desc:   "commaSeparated",
+			path:   "/gBar/method1",
+			md:     metadata.Pairs("n1", "v1", "n1", "v2", "n1", "v3"),
+			wantKM: KeyMap{Map: map[string]string{"k1": "v1,v2,v3"}, Str: "k1=v1,v2,v3"},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			if gotKM := bm.RLSKey(test.md, "dummy-host", test.path); !cmp.Equal(gotKM, test.wantKM) {
+				t.Errorf("RLSKey(%+v, %s) = %+v, want %+v", test.md, test.path, gotKM, test.wantKM)
+			}
+		})
+	}
+}
+
+func TestMapToString(t *testing.T) {
+	tests := []struct {
+		desc    string
+		input   map[string]string
+		wantStr string
+	}{
+		{
+			desc:    "empty map",
+			input:   nil,
+			wantStr: "",
+		},
+		{
+			desc: "one key",
+			input: map[string]string{
+				"k1": "v1",
+			},
+			wantStr: "k1=v1",
+		},
+		{
+			desc: "sorted keys",
+			input: map[string]string{
+				"k1": "v1",
+				"k2": "v2",
+				"k3": "v3",
+			},
+			wantStr: "k1=v1,k2=v2,k3=v3",
+		},
+		{
+			desc: "unsorted keys",
+			input: map[string]string{
+				"k3": "v3",
+				"k1": "v1",
+				"k2": "v2",
+			},
+			wantStr: "k1=v1,k2=v2,k3=v3",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			if gotStr := mapToString(test.input); gotStr != test.wantStr {
+				t.Errorf("mapToString(%v) = %s, want %s", test.input, gotStr, test.wantStr)
+			}
+		})
+	}
+}
+
+func TestBuilderMapEqual(t *testing.T) {
+	tests := []struct {
+		desc      string
+		a         BuilderMap
+		b         BuilderMap
+		wantEqual bool
+	}{
+		{
+			desc:      "nil builder maps",
+			a:         nil,
+			b:         nil,
+			wantEqual: true,
+		},
+		{
+			desc:      "empty builder maps",
+			a:         make(map[string]builder),
+			b:         make(map[string]builder),
+			wantEqual: true,
+		},
+		{
+			desc:      "nil and non-nil builder maps",
+			a:         nil,
+			b:         map[string]builder{"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}}},
+			wantEqual: false,
+		},
+		{
+			desc:      "empty and non-empty builder maps",
+			a:         make(map[string]builder),
+			b:         map[string]builder{"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}}},
+			wantEqual: false,
+		},
+		{
+			desc: "different number of map keys",
+			a: map[string]builder{
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+				"/gBar/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			b: map[string]builder{
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			wantEqual: false,
+		},
+		{
+			desc: "different map keys",
+			a: map[string]builder{
+				"/gBar/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			b: map[string]builder{
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			wantEqual: false,
+		},
+		{
+			desc: "equal keys different values",
+			a: map[string]builder{
+				"/gBar/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1", "n2"}}}},
+			},
+			b: map[string]builder{
+				"/gBar/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			wantEqual: false,
+		},
+		{
+			desc: "good match",
+			a: map[string]builder{
+				"/gBar/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			b: map[string]builder{
+				"/gBar/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+				"/gFoo/": {headerKeys: []matcher{{key: "k1", names: []string{"n1"}}}},
+			},
+			wantEqual: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			if gotEqual := test.a.Equal(test.b); gotEqual != test.wantEqual {
+				t.Errorf("BuilderMap.Equal(%v, %v) = %v, want %v", test.a, test.b, gotEqual, test.wantEqual)
+			}
+		})
+	}
+}
+
+func TestBuilderEqual(t *testing.T) {
+	tests := []struct {
+		desc      string
+		a         builder
+		b         builder
+		wantEqual bool
+	}{
+		{
+			desc:      "nil builders",
+			a:         builder{headerKeys: nil},
+			b:         builder{headerKeys: nil},
+			wantEqual: true,
+		},
+		{
+			desc:      "empty builders",
+			a:         builder{headerKeys: []matcher{}},
+			b:         builder{headerKeys: []matcher{}},
+			wantEqual: true,
+		},
+		{
+			desc:      "empty and non-empty builders",
+			a:         builder{headerKeys: []matcher{}},
+			b:         builder{headerKeys: []matcher{{key: "foo"}}},
+			wantEqual: false,
+		},
+		{
+			desc:      "different number of headerKeys",
+			a:         builder{headerKeys: []matcher{{key: "foo"}, {key: "bar"}}},
+			b:         builder{headerKeys: []matcher{{key: "foo"}}},
+			wantEqual: false,
+		},
+		{
+			desc:      "equal number but differing headerKeys",
+			a:         builder{headerKeys: []matcher{{key: "bar"}}},
+			b:         builder{headerKeys: []matcher{{key: "foo"}}},
+			wantEqual: false,
+		},
+		{
+			desc:      "different number of constantKeys",
+			a:         builder{constantKeys: map[string]string{"k1": "v1"}},
+			b:         builder{constantKeys: map[string]string{"k1": "v1", "k2": "v2"}},
+			wantEqual: false,
+		},
+		{
+			desc:      "equal number but differing constantKeys",
+			a:         builder{constantKeys: map[string]string{"k1": "v1"}},
+			b:         builder{constantKeys: map[string]string{"k2": "v2"}},
+			wantEqual: false,
+		},
+		{
+			desc:      "different hostKey",
+			a:         builder{hostKey: "host1"},
+			b:         builder{hostKey: "host2"},
+			wantEqual: false,
+		},
+		{
+			desc:      "different serviceKey",
+			a:         builder{hostKey: "service1"},
+			b:         builder{hostKey: "service2"},
+			wantEqual: false,
+		},
+		{
+			desc:      "different methodKey",
+			a:         builder{hostKey: "method1"},
+			b:         builder{hostKey: "method2"},
+			wantEqual: false,
+		},
+		{
+			desc: "equal",
+			a: builder{
+				headerKeys:   []matcher{{key: "foo"}},
+				constantKeys: map[string]string{"k1": "v1"},
+				hostKey:      "host",
+				serviceKey:   "/service/",
+				methodKey:    "method",
+			},
+			b: builder{
+				headerKeys:   []matcher{{key: "foo"}},
+				constantKeys: map[string]string{"k1": "v1"},
+				hostKey:      "host",
+				serviceKey:   "/service/",
+				methodKey:    "method",
+			},
+			wantEqual: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			t.Run(test.desc, func(t *testing.T) {
+				if gotEqual := test.a.Equal(test.b); gotEqual != test.wantEqual {
+					t.Errorf("builder.Equal(%v, %v) = %v, want %v", test.a, test.b, gotEqual, test.wantEqual)
+				}
+			})
+		})
+	}
+}
+
+// matcher helps extract a key from request headers based on a given name.
+func TestMatcherEqual(t *testing.T) {
+	tests := []struct {
+		desc      string
+		a         matcher
+		b         matcher
+		wantEqual bool
+	}{
+		{
+			desc:      "different keys",
+			a:         matcher{key: "foo"},
+			b:         matcher{key: "bar"},
+			wantEqual: false,
+		},
+		{
+			desc:      "different number of names",
+			a:         matcher{key: "foo", names: []string{"v1", "v2"}},
+			b:         matcher{key: "foo", names: []string{"v1"}},
+			wantEqual: false,
+		},
+		{
+			desc:      "equal number but differing names",
+			a:         matcher{key: "foo", names: []string{"v1", "v2"}},
+			b:         matcher{key: "foo", names: []string{"v1", "v22"}},
+			wantEqual: false,
+		},
+		{
+			desc:      "same names in different order",
+			a:         matcher{key: "foo", names: []string{"v2", "v1"}},
+			b:         matcher{key: "foo", names: []string{"v1", "v3"}},
+			wantEqual: false,
+		},
+		{
+			desc:      "good match",
+			a:         matcher{key: "foo", names: []string{"v1", "v2"}},
+			b:         matcher{key: "foo", names: []string{"v1", "v2"}},
+			wantEqual: true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			if gotEqual := test.a.Equal(test.b); gotEqual != test.wantEqual {
+				t.Errorf("matcher.Equal(%v, %v) = %v, want %v", test.a, test.b, gotEqual, test.wantEqual)
+			}
+		})
+	}
+}