[fuzz] fix filter crashes from OSS fuzz (envoyproxy#12152)

* fix filter fuzzer crash from OSS fuzz by checking for non-implemented proto fields
This will raise an exception that will be caught and abort the test run when an unimplemented oneof field is hit by the fuzzer

Signed-off-by: Sam Flattery <[email protected]>

Author: samflattery

api/envoy/config/tap/v3/common.proto

@@ -231,6 +231,7 @@ message OutputSink {
 
     // [#not-implemented-hide:]
     // GrpcService to stream data to. The format argument must be PROTO_BINARY.
+    // [#comment: TODO(samflattery): remove cleanup in uber_per_filter.cc once implemented]
     StreamingGrpcSink streaming_grpc = 4;
   }
 }

api/envoy/config/tap/v4alpha/common.proto

@@ -103,6 +103,19 @@ void cleanTapConfig(Protobuf::Message* message) {
     config.mutable_common_config()->mutable_static_config()->mutable_match_config()->set_any_match(
         true);
   }
+  // TODO(samflattery): remove once StreamingGrpcSink is implemented
+  else if (config.common_config().config_type_case() ==
+               envoy::extensions::common::tap::v3::CommonExtensionConfig::ConfigTypeCase::
+                   kStaticConfig &&
+           config.common_config()
+                   .static_config()
+                   .output_config()
+                   .sinks(0)
+                   .output_sink_type_case() ==
+               envoy::config::tap::v3::OutputSink::OutputSinkTypeCase::kStreamingGrpc) {
+    // will be caught in UberFilterFuzzer::fuzz
+    throw EnvoyException("received input with not implemented output_sink_type StreamingGrpcSink");
+  }
 }
 
 void UberFilterFuzzer::cleanFuzzedConfig(absl::string_view filter_name,

generated_api_shadow/envoy/config/tap/v3/common.proto

@@ -1111,6 +1111,7 @@ tuples
 typedef
 typeid
 typesafe
+uber
 ucontext
 udpa
 uint