scripteq: simple helper for comparing scripts.

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

bitcoin/script.c

@@ -476,3 +476,13 @@ u8 **bitcoin_witness_secret(const tal_t *ctx,
 
 	return witness;
 }
+
+bool scripteq(const u8 *s1, size_t s1len, const u8 *s2, size_t s2len)
+{
+	memcheck(s1, s1len);
+	memcheck(s2, s2len);
+
+	if (s1len != s2len)
+		return false;
+	return memcmp(s1, s2, s1len) == 0;
+}

bitcoin/script.h

@@ -89,4 +89,7 @@ u8 **bitcoin_witness_secret(const tal_t *ctx,
 /* Is this a pay to script hash? */
 bool is_p2sh(const u8 *script, size_t script_len);
 
+/* Are these two scripts equal? */
+bool scripteq(const u8 *s1, size_t s1len, const u8 *s2, size_t s2len);
+
 #endif /* LIGHTNING_BITCOIN_SCRIPT_H */

find_p2sh_out.c

@@ -10,9 +10,10 @@ static u32 find_output(const struct bitcoin_tx *tx, const u8 *scriptpubkey)
 	u32 i;
 
 	for (i = 0; i < tx->output_count; i++) {
-		if (tx->output[i].script_length != tal_count(scriptpubkey))
+		if (scripteq(tx->output[i].script,
-			continue;
+			     tx->output[i].script_length,
-		if (memcmp(tx->output[i].script, scriptpubkey, tal_count(scriptpubkey)) == 0)
+			     scriptpubkey,
+			     tal_count(scriptpubkey)))
 			break;
 	}
 	/* FIXME: Return failure! */