xds: remove path matcher format requirements and default route requirement for routing enabled (v1.30.x backport) (#7063) (#7070)

Remove requirement for formats of path matchers. Only require the last route to be the default route for the case when routing is disabled.

xds/src/main/java/io/grpc/xds/EnvoyProtoData.java

@@ -444,6 +444,7 @@ final class EnvoyProtoData {
       return routeAction;
     }
 
+    // TODO(chengyuanzhang): delete and do not use after routing feature is always ON.
     boolean isDefaultRoute() {
       return routeMatch.isMatchAll();
     }
@@ -553,16 +554,10 @@ final class EnvoyProtoData {
       return pathExactMatch;
     }
 
-    boolean isMatchAll() {
+    // TODO(chengyuanzhang): delete and do not use after routing feature is always ON.
-      if (pathSafeRegExMatch != null || fractionMatch != null) {
+    private boolean isMatchAll() {
-        return false;
+      // For backward compatibility, all the other matchers are ignored. When routing is enabled,
-      }
+      // we should never care if a matcher matches all requests.
-      if (!headerMatchers.isEmpty()) {
-        return false;
-      }
-      if (pathExactMatch != null) {
-        return false;
-      }
       if (pathPrefixMatch != null) {
         return pathPrefixMatch.isEmpty() || pathPrefixMatch.equals("/");
       }
@@ -655,27 +650,9 @@ final class EnvoyProtoData {
       switch (proto.getPathSpecifierCase()) {
         case PREFIX:
           prefixPathMatch = proto.getPrefix();
-          // Supported prefix match format:
-          // "", "/" (default)
-          // "/service/"
-          if (!prefixPathMatch.isEmpty() && !prefixPathMatch.equals("/")) {
-            if (!prefixPathMatch.startsWith("/") || !prefixPathMatch.endsWith("/")
-                || prefixPathMatch.length() < 3) {
-              return StructOrError.fromError(
-                  "Invalid format of prefix path match: " + prefixPathMatch);
-            }
-          }
           break;
         case PATH:
           exactPathMatch = proto.getPath();
-          int lastSlash = exactPathMatch.lastIndexOf('/');
-          // Supported exact match format:
-          // "/service/method"
-          if (!exactPathMatch.startsWith("/") || lastSlash == 0
-              || lastSlash == exactPathMatch.length() - 1) {
-            return StructOrError.fromError(
-                "Invalid format of exact path match: " + exactPathMatch);
-          }
           break;
         case REGEX:
           return StructOrError.fromError("Unsupported path match type: regex");

xds/src/main/java/io/grpc/xds/XdsClientImpl.java

@@ -858,14 +858,14 @@ final class XdsClientImpl extends XdsClient {
       throw new InvalidProtoDataException(
           "Virtual host [" + virtualHost.getName() + "] contains no usable route");
     }
-    // The last route must be a default route.
+
-    if (!Iterables.getLast(routes).isDefaultRoute()) {
-      throw new InvalidProtoDataException(
-          "Virtual host [" + virtualHost.getName()
-              + "] contains non-default route as the last route");
-    }
     if (!enableExperimentalRouting) {
       EnvoyProtoData.Route defaultRoute = Iterables.getLast(routes);
+      if (!defaultRoute.isDefaultRoute()) {
+        throw new InvalidProtoDataException(
+            "Virtual host [" + virtualHost.getName()
+                + "] contains non-default route as the last route");
+      }
       return Collections.singletonList(defaultRoute);
     }
     return Collections.unmodifiableList(routes);

xds/src/test/java/io/grpc/xds/EnvoyProtoDataTest.java

@@ -246,51 +246,6 @@ public class EnvoyProtoDataTest {
     assertThat(unsetStruct.getStruct()).isNull();
   }
 
-  @Test
-  public void convertRouteMatch_pathMatchFormat() {
-    StructOrError<RouteMatch> struct1 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto("", null));
-    StructOrError<RouteMatch> struct2 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto("/", null));
-    StructOrError<RouteMatch> struct3 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto("/service", null));
-    StructOrError<RouteMatch> struct4 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto("/service/", null));
-    StructOrError<RouteMatch> struct5 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto(null, ""));
-    StructOrError<RouteMatch> struct6 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto(null, "/service/method"));
-    StructOrError<RouteMatch> struct7 =
-        RouteMatch.fromEnvoyProtoRouteMatch(buildSimpleRouteMatchProto(null, "/service/method/"));
-    StructOrError<RouteMatch> struct8 =
-        RouteMatch.fromEnvoyProtoRouteMatch(
-            io.envoyproxy.envoy.api.v2.route.RouteMatch.newBuilder()
-                .setSafeRegex(
-                    io.envoyproxy.envoy.type.matcher.RegexMatcher.newBuilder().setRegex("["))
-                .build());
-
-    assertThat(struct1.getStruct()).isNotNull();
-    assertThat(struct2.getStruct()).isNotNull();
-    assertThat(struct3.getStruct()).isNull();
-    assertThat(struct4.getStruct()).isNotNull();
-    assertThat(struct5.getStruct()).isNull();
-    assertThat(struct6.getStruct()).isNotNull();
-    assertThat(struct7.getStruct()).isNull();
-    assertThat(struct8.getStruct()).isNull();
-  }
-
-  private static io.envoyproxy.envoy.api.v2.route.RouteMatch buildSimpleRouteMatchProto(
-      @Nullable String pathPrefix, @Nullable String path) {
-    io.envoyproxy.envoy.api.v2.route.RouteMatch.Builder builder =
-        io.envoyproxy.envoy.api.v2.route.RouteMatch.newBuilder();
-    if (pathPrefix != null) {
-      builder.setPrefix(pathPrefix);
-    } else if (path != null) {
-      builder.setPath(path);
-    }
-    return builder.build();
-  }
-
   @Test
   public void convertRouteMatch_withHeaderMatching() {
     io.envoyproxy.envoy.api.v2.route.RouteMatch proto =