common/node_id: runtime assertion override, not separate compile time for fuzzing.

This makes it trivial to run the fuzz tests as unit tests in non-fuzzing mode.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/node_id.c

@@ -56,14 +56,16 @@ void fromwire_node_id(const u8 **cursor, size_t *max, struct node_id *id)
 	fromwire(cursor, max, &id->k, sizeof(id->k));
 }
 
+bool dev_towire_allow_invalid_node_id = false;
+
 void towire_node_id(u8 **pptr, const struct node_id *id)
 {
-#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 	/* Cheap sanity check. For wire fuzzing, we only care about correct
 	 * encoding of node IDs and not whether the IDs are valid, so we disable
 	 * this check while fuzzing. */
+	if (!dev_towire_allow_invalid_node_id)
 		assert(id->k[0] == 0x2 || id->k[0] == 0x3);
-#endif
+
 	towire(pptr, id->k, sizeof(id->k));
 }
 

common/node_id.h

@@ -48,6 +48,9 @@ static inline int node_id_idx(const struct node_id *id1,
 void towire_node_id(u8 **pptr, const struct node_id *id);
 void fromwire_node_id(const u8 **cursor, size_t *max, struct node_id *id);
 
+/* Fuzzer creates these, so sets this flag to allow it */
+extern bool dev_towire_allow_invalid_node_id;
+
 /* Hash table functions for node ids */
 static inline const struct node_id *node_id_keyof(const struct node_id *id)
 {

tests/fuzz/wire.h

@@ -21,7 +21,7 @@ static u8 *prefix_arr(const u8 *data, size_t size, u16 prefix)
 }
 
 /* The init function used by all fuzz-wire-* targets. */
-void init(int *argc, char ***argv) { common_setup("fuzzer"); }
+void init(int *argc, char ***argv) { common_setup("fuzzer"); dev_towire_allow_invalid_node_id = true; }
 
 /* Test that decoding arbitrary data does not crash. Then, if the data was
  * successfully decoded, test that encoding and decoding the message does not