C bindings: Implement _Validate(), and some pre-requisites

mojo/public/c/bindings/lib/message.c

Index: mojo/public/c/bindings/lib/message.c
diff --git a/mojo/public/c/bindings/lib/message.c b/mojo/public/c/bindings/lib/message.c
index 9b2d27dce004f9b4f9e8c5fad1d8d3e04c960e17..6c766e3009fe7b192483c4d6a116e3bfcd0cb8b3 100644
--- a/mojo/public/c/bindings/lib/message.c
+++ b/mojo/public/c/bindings/lib/message.c
@@ -12,10 +12,10 @@ MojomValidationResult MojomMessage_ValidateHeader(const void* in_buf,
                                                   uint32_t in_buf_size) {
   const struct MojomStructHeader* header =
     (const struct MojomStructHeader*)in_buf;
+
   if (in_buf_size < sizeof(struct MojomStructHeader) ||
-      in_buf_size < header->num_bytes) {
-    return MOJOM_VALIDATION_UNEXPECTED_STRUCT_HEADER;
-  }
+      in_buf_size < header->num_bytes)
+    return MOJOM_VALIDATION_ILLEGAL_MEMORY_RANGE;
 
   const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
   if (header->version == 0u) {
@@ -47,3 +47,28 @@ MojomValidationResult MojomMessage_ValidateHeader(const void* in_buf,
   // Accept unknown versions of the message header to be future-proof.
   return MOJOM_VALIDATION_ERROR_NONE;
 }
+
+MojomValidationResult MojomMessage_ValidateRequestExpectingResponse(
+    const void* in_buf) {
+  const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
+  return (msg->flags & MOJOM_MESSAGE_FLAGS_EXPECTS_RESPONSE)
+             ? MOJOM_VALIDATION_ERROR_NONE
+             : MOJOM_VALIDATION_MESSAGE_HEADER_INVALID_FLAGS;
+}
+
+MojomValidationResult MojomMessage_ValidateRequestWithoutResponse(
+    const void* in_buf) {
+  const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
+  return (!(msg->flags & MOJOM_MESSAGE_FLAGS_EXPECTS_RESPONSE) &&
+                 !(msg->flags & MOJOM_MESSAGE_FLAGS_IS_RESPONSE))
+             ? MOJOM_VALIDATION_ERROR_NONE
+             : MOJOM_VALIDATION_MESSAGE_HEADER_INVALID_FLAGS;
+}
+
+MojomValidationResult MojomMessage_ValidateResponse(
+    const void* in_buf) {
+  const struct MojomMessage* msg = (const struct MojomMessage*)in_buf;
+  return (msg->flags & MOJOM_MESSAGE_FLAGS_IS_RESPONSE)
+             ? MOJOM_VALIDATION_ERROR_NONE
+             : MOJOM_VALIDATION_MESSAGE_HEADER_INVALID_FLAGS;
+}