daemon: check protobuf-c version, report failure.

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

daemon/cryptopkt.c

@@ -184,9 +184,10 @@ static Pkt *decrypt_pkt(struct peer *peer, struct crypto_pkt *cpkt,
 	prototal.allocator_data = tal(iod, char);
 
 	ret = pkt__unpack(&prototal, data_len, cpkt->data);
-	if (!ret)
+	if (!ret) {
+		log_unusual(peer->log, "Packet failed to unpack!");
 		tal_free(prototal.allocator_data);
-	else
+	} else
 		/* Make sure packet owns contents */
 		tal_steal(ret, prototal.allocator_data);
 	return ret;

daemon/lightningd.c

@@ -207,6 +207,10 @@ int main(int argc, char *argv[])
 	err_set_progname(argv[0]);
 	opt_set_alloc(opt_allocfn, tal_reallocfn, tal_freefn);
 
+	if (!streq(protobuf_c_version(), PROTOBUF_C_VERSION))
+		errx(1, "Compiled against protobuf %s, but have %s",
+		     PROTOBUF_C_VERSION, protobuf_c_version());
+	
 	opt_register_noarg("--help|-h", opt_usage_and_exit,
 			   "\n"
 			   "A bitcoin lightning daemon.",