permute_tx: generic pointer map.

Turns out we want to permute transactions for the wallet too, so we
use void ** rather than assume we're shuffling htlc ** (and do inputs,
too!).

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

lightningd/commit_tx.c

@@ -318,7 +318,8 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 	 * 7. Sort the outputs into [BIP 69
 	 *    order](#transaction-input-and-output-ordering)
 	 */
-	permute_outputs(tx->output, tal_count(tx->output), *htlcmap);
+	permute_outputs(tx->output, tal_count(tx->output),
+			(const void **)*htlcmap);
 
 	/* BOLT #3:
 	 *

permute_tx.c

@@ -34,42 +34,51 @@ static size_t find_best_in(struct bitcoin_tx_input *inputs, size_t num)
 }
 
 static void swap_inputs(struct bitcoin_tx_input *inputs,
+			const void **map,
 			size_t i1, size_t i2)
 {
 	struct bitcoin_tx_input tmpinput;
+	const void *tmp;
 
 	tmpinput = inputs[i1];
 	inputs[i1] = inputs[i2];
 	inputs[i2] = tmpinput;
+
+	if (map) {
+		tmp = map[i1];
+		map[i1] = map[i2];
+		map[i2] = tmp;
+	}
 }
 
-void permute_inputs(struct bitcoin_tx_input *inputs, size_t num_inputs)
+void permute_inputs(struct bitcoin_tx_input *inputs, size_t num_inputs,
+		    const void **map)
 {
 	size_t i;
 
 	/* Now do a dumb sort (num_inputs is small). */
 	for (i = 0; i < num_inputs; i++) {
 		/* Swap best into first place. */
-		swap_inputs(inputs,
+		swap_inputs(inputs, map,
 			    i, i + find_best_in(inputs + i, num_inputs - i));
 	}
 }
 
 static void swap_outputs(struct bitcoin_tx_output *outputs,
-			 const struct htlc **htlcmap,
+			 const void **map,
 			 size_t i1, size_t i2)
 {
 	struct bitcoin_tx_output tmpoutput;
-	const struct htlc *tmphtlc;
+	const void *tmp;
 
 	tmpoutput = outputs[i1];
 	outputs[i1] = outputs[i2];
 	outputs[i2] = tmpoutput;
 
-	if (htlcmap) {
-		tmphtlc = htlcmap[i1];
-		htlcmap[i1] = htlcmap[i2];
-		htlcmap[i2] = tmphtlc;
+	if (map) {
+		tmp = map[i1];
+		map[i1] = map[i2];
+		map[i2] = tmp;
 	}
 }
 
@@ -106,16 +115,15 @@ static size_t find_best_out(struct bitcoin_tx_output *outputs, size_t num)
 	return best;
 }
 
-void permute_outputs(struct bitcoin_tx_output *outputs,
-		     size_t num_outputs,
-		     const struct htlc **htlcmap)
+void permute_outputs(struct bitcoin_tx_output *outputs, size_t num_outputs,
+		     const void **map)
 {
 	size_t i;
 
 	/* Now do a dumb sort (num_outputs is small). */
 	for (i = 0; i < num_outputs; i++) {
 		/* Swap best into first place. */
-		swap_outputs(outputs, htlcmap,
+		swap_outputs(outputs, map,
 			     i, i + find_best_out(outputs + i, num_outputs - i));
 	}
 }

permute_tx.h

@@ -6,13 +6,14 @@
 struct htlc;
 
 /* Permute the transaction into BIP69 order. */
-void permute_inputs(struct bitcoin_tx_input *inputs, size_t num_inputs);
+void permute_inputs(struct bitcoin_tx_input *inputs, size_t num_inputs,
+		    const void **map);
 
-/* If @htlcmap is non-NULL, it will be permuted the same as the outputs.
+/* If @map is non-NULL, it will be permuted the same as the outputs.
  *
- * So the caller initiates the htlcsmap with which htlcs are used, it
- * can easily see which htlc (if any) is in output #0 with htlcmap[0].
+ * So the caller initiates the map with which htlcs are used, it
+ * can easily see which htlc (if any) is in output #0 with map[0].
  */
 void permute_outputs(struct bitcoin_tx_output *outputs, size_t num_outputs,
-		     const struct htlc **htlcmap);
+		     const void **map);
 #endif /* LIGHTNING_PERMUTE_TX_H */