grpc-pb: Skip unknown fields

Signed-off-by: Johannes Zottele <[email protected]>

Author: Jozott00

grpc/grpc-core/src/commonMain/kotlin/kotlinx/rpc/grpc/pb/WireDecoder.kt

@@ -88,6 +88,17 @@ public interface WireDecoder : AutoCloseable {
         decoder(msg, this)
         popLimit(limit)
     }
+
+    public fun skipValue(writeType: WireType) {
+        when (writeType) {
+            WireType.VARINT -> readInt64()
+            WireType.FIXED32 -> readFixed32()
+            WireType.FIXED64 -> readFixed64()
+            WireType.LENGTH_DELIMITED -> readBytes()
+            WireType.START_GROUP -> error("Unexpected START_GROUP wire type")
+            WireType.END_GROUP -> {} // nothing to do
+        }
+    }
 }
 
 /**

grpc/grpc-core/src/commonTest/kotlin/kotlinx/rpc/grpc/pb/ProtosTest.kt

@@ -34,6 +34,24 @@ class ProtosTest {
         return codec.decode(source)
     }
 
+    @Test
+    fun testUnknownFieldsDontCrash() {
+        val buffer = Buffer()
+        val encoder = WireEncoder(buffer)
+        // optional sint32 sint32 = 7
+        encoder.writeSInt32(7, 12)
+        // optional sint64 sint64 = 8; (unknown as wrong wire-type)
+        encoder.writeFloat(8, 2f)
+        // optional fixed32 fixed32 = 9;
+        encoder.writeFixed32(9, 1234u)
+        encoder.flush()
+
+        val decoded = AllPrimitivesInternal.CODEC.decode(buffer)
+        assertEquals(12, decoded.sint32)
+        assertNull(decoded.sint64)
+        assertEquals(1234u, decoded.fixed32)
+    }
+
     @Test
     fun testAllPrimitiveProto() {
         val msg = AllPrimitives {

protoc-gen/src/main/kotlin/kotlinx/rpc/protobuf/ModelToKotlinCommonGenerator.kt

@@ -288,7 +288,10 @@ class ModelToKotlinCommonGenerator(
             code("val tag = decoder.readTag() ?: break // EOF, we read the whole message")
             whenBlock {
                 declaration.fields().forEach { (_, field) -> readMatchCase(field) }
-                whenCase("else") { code("TODO(\"Handle unknown fields: \$tag\")") }
+                whenCase("else") {
+                    code("// we are currently just skipping unknown fields (KRPC-191)")
+                    code("decoder.skipValue(tag.wireType)")
+                }
             }
         }
         ifBranch(