psbt-common: shared psbt utilities

includes facilities for - sorting psbt inputs by serial_id - sorting psbt outputs by serial_id - adding a serial_id - getting a serial_id - finding the diffset between two psbts - adding a max_len to a psbt input - getting a max_len from a psbt input
4 years ago · c0d0272eac
3 changed files with 535 additions and 0 deletions
--- a/common/Makefile
+++ b/common/Makefile
@ -55,6 +55,7 @@ COMMON_SRC_NOGEN :=				\
 	common/peer_failed.c			\
 	common/permute_tx.c			\
 	common/ping.c				\
+	common/psbt_open.c			\
 	common/pseudorand.c			\
 	common/read_peer_msg.c			\
 	common/setup.c				\
--- a/common/psbt_open.c
+++ b/common/psbt_open.c
@ -0,0 +1,389 @@
+#include "common/psbt_open.h"
+#include <assert.h>
+#include <bitcoin/psbt.h>
+#include <bitcoin/script.h>
+#include <bitcoin/tx.h>
+#include <ccan/asort/asort.h>
+#include <ccan/ccan/mem/mem.h>
+#include <common/utils.h>
+
+bool psbt_get_serial_id(const struct wally_map *map, u16 *serial_id)
+{
+	size_t value_len;
+	void *result = psbt_get_lightning(map, PSBT_TYPE_SERIAL_ID, &value_len);
+	if (!result)
+		return false;
+
+	if (value_len != sizeof(*serial_id))
+		return false;
+
+	memcpy(serial_id, result, value_len);
+	return true;
+}
+
+static int compare_serials(const struct wally_map *map_a,
+			   const struct wally_map *map_b)
+{
+	u16 serial_left, serial_right;
+	bool ok;
+
+	ok = psbt_get_serial_id(map_a, &serial_left);
+	assert(ok);
+	ok = psbt_get_serial_id(map_b, &serial_right);
+	assert(ok);
+	if (serial_left > serial_right)
+		return 1;
+	if (serial_left < serial_right)
+		return -1;
+	return 0;
+}
+
+static int compare_inputs_at(const struct input_set *a,
+			     const struct input_set *b,
+			     void *unused UNUSED)
+{
+	return compare_serials(&a->input.unknowns,
+			       &b->input.unknowns);
+}
+
+static int compare_outputs_at(const struct output_set *a,
+			      const struct output_set *b,
+			      void *unused UNUSED)
+{
+	return compare_serials(&a->output.unknowns,
+			       &b->output.unknowns);
+}
+
+static const u8 *linearize_input(const tal_t *ctx,
+				 const struct wally_psbt_input *in,
+				 const struct wally_tx_input *tx_in)
+{
+	struct wally_psbt *psbt = create_psbt(NULL, 1, 0);
+	size_t byte_len;
+
+
+	if (wally_tx_add_input(psbt->tx, tx_in) != WALLY_OK)
+		abort();
+	psbt->inputs[0] = *in;
+	psbt->num_inputs++;
+
+	const u8 *bytes = psbt_get_bytes(ctx, psbt, &byte_len);
+
+	/* Hide the inputs we added, so it doesn't get freed */
+	psbt->num_inputs--;
+	tal_free(psbt);
+	return bytes;
+}
+
+static const u8 *linearize_output(const tal_t *ctx,
+				  const struct wally_psbt_output *out,
+				  const struct wally_tx_output *tx_out)
+{
+	struct wally_psbt *psbt = create_psbt(NULL, 1, 1);
+	size_t byte_len;
+	struct bitcoin_txid txid;
+
+	/* Add a 'fake' input so this will linearize the tx */
+	memset(&txid, 0, sizeof(txid));
+	psbt_append_input(psbt, &txid, 0, 0);
+
+	if (wally_tx_add_output(psbt->tx, tx_out) != WALLY_OK)
+		abort();
+	psbt->outputs[0] = *out;
+	psbt->num_outputs++;
+
+	const u8 *bytes = psbt_get_bytes(ctx, psbt, &byte_len);
+
+	/* Hide the outputs we added, so it doesn't get freed */
+	psbt->num_outputs--;
+	tal_free(psbt);
+	return bytes;
+}
+
+static bool input_identical(const struct wally_psbt *a,
+			    size_t a_index,
+			    const struct wally_psbt *b,
+			    size_t b_index)
+{
+	const u8 *a_in = linearize_input(tmpctx,
+					 &a->inputs[a_index],
+					 &a->tx->inputs[a_index]);
+	const u8 *b_in = linearize_input(tmpctx,
+					 &b->inputs[b_index],
+					 &b->tx->inputs[b_index]);
+
+	return memeq(a_in, tal_bytelen(a_in),
+		     b_in, tal_bytelen(b_in));
+}
+
+static bool output_identical(const struct wally_psbt *a,
+			     size_t a_index,
+			     const struct wally_psbt *b,
+			     size_t b_index)
+{
+	const u8 *a_out = linearize_output(tmpctx,
+					   &a->outputs[a_index],
+					   &a->tx->outputs[a_index]);
+	const u8 *b_out = linearize_output(tmpctx,
+					   &b->outputs[b_index],
+					   &b->tx->outputs[b_index]);
+
+	return memeq(a_out, tal_bytelen(a_out),
+		     b_out, tal_bytelen(b_out));
+}
+
+static void sort_inputs(struct wally_psbt *psbt)
+{
+	/* Build an input map */
+	struct input_set *set = tal_arr(NULL,
+					struct input_set,
+					psbt->num_inputs);
+
+	for (size_t i = 0; i < tal_count(set); i++) {
+		set[i].tx_input = psbt->tx->inputs[i];
+		set[i].input = psbt->inputs[i];
+	}
+
+	asort(set, tal_count(set),
+	      compare_inputs_at, NULL);
+
+	/* Put PSBT parts into place */
+	for (size_t i = 0; i < tal_count(set); i++) {
+		psbt->inputs[i] = set[i].input;
+		psbt->tx->inputs[i] = set[i].tx_input;
+	}
+
+	tal_free(set);
+}
+
+static void sort_outputs(struct wally_psbt *psbt)
+{
+	/* Build an output map */
+	struct output_set *set = tal_arr(NULL,
+					 struct output_set,
+					 psbt->num_outputs);
+	for (size_t i = 0; i < tal_count(set); i++) {
+		set[i].tx_output = psbt->tx->outputs[i];
+		set[i].output = psbt->outputs[i];
+	}
+
+	asort(set, tal_count(set),
+	      compare_outputs_at, NULL);
+
+	/* Put PSBT parts into place */
+	for (size_t i = 0; i < tal_count(set); i++) {
+		psbt->outputs[i] = set[i].output;
+		psbt->tx->outputs[i] = set[i].tx_output;
+	}
+
+	tal_free(set);
+}
+
+void psbt_sort_by_serial_id(struct wally_psbt *psbt)
+{
+	sort_inputs(psbt);
+	sort_outputs(psbt);
+}
+
+#define ADD(type, add_to, from, index)				\
+	do {							\
+		struct type##_set a;				\
+		a.type = from->type##s[index];			\
+		a.tx_##type = from->tx->type##s[index]; 	\
+		tal_arr_expand(add_to, a);			\
+	} while (0)
+
+/* this requires having a serial_id entry on everything */
+/* YOU MUST KEEP orig + new AROUND TO USE THE RESULTING SETS */
+bool psbt_has_diff(const tal_t *ctx,
+		   struct wally_psbt *orig,
+		   struct wally_psbt *new,
+		   struct input_set **added_ins,
+		   struct input_set **rm_ins,
+		   struct output_set **added_outs,
+		   struct output_set **rm_outs)
+{
+	int result;
+	size_t i = 0, j = 0;
+
+	psbt_sort_by_serial_id(orig);
+	psbt_sort_by_serial_id(new);
+
+	*added_ins = tal_arr(ctx, struct input_set, 0);
+	*rm_ins = tal_arr(ctx, struct input_set, 0);
+	*added_outs = tal_arr(ctx, struct output_set, 0);
+	*rm_outs = tal_arr(ctx, struct output_set, 0);
+
+	/* Find the input diff */
+	while (i < orig->num_inputs || j < new->num_inputs) {
+		if (i >= orig->num_inputs) {
+			ADD(input, added_ins, new, j);
+			j++;
+			continue;
+		}
+		if (j >= new->num_inputs) {
+			ADD(input, rm_ins, orig, i);
+			i++;
+			continue;
+		}
+
+		result = compare_serials(&orig->inputs[i].unknowns,
+					 &new->inputs[j].unknowns);
+		if (result == -1) {
+			ADD(input, rm_ins, orig, i);
+			i++;
+			continue;
+		}
+		if (result == 1) {
+			ADD(input, added_ins, new, j);
+			j++;
+			continue;
+		}
+
+		if (!input_identical(orig, i, new, j)) {
+			ADD(input, rm_ins, orig, i);
+			ADD(input, added_ins, new, j);
+		}
+		i++;
+		j++;
+	}
+	/* Find the output diff */
+	i = 0;
+	j = 0;
+	while (i < orig->num_outputs || j < new->num_outputs) {
+		if (i >= orig->num_outputs) {
+			ADD(output, added_outs, new, j);
+			j++;
+			continue;
+		}
+		if (j >= new->num_outputs) {
+			ADD(output, rm_outs, orig, i);
+			i++;
+			continue;
+		}
+
+		result = compare_serials(&orig->outputs[i].unknowns,
+					 &new->outputs[j].unknowns);
+		if (result == -1) {
+			ADD(output, rm_outs, orig, i);
+			i++;
+			continue;
+		}
+		if (result == 1) {
+			ADD(output, added_outs, new, j);
+			j++;
+			continue;
+		}
+		if (!output_identical(orig, i, new, j)) {
+			ADD(output, rm_outs, orig, i);
+			ADD(output, added_outs, new, j);
+		}
+		i++;
+		j++;
+	}
+
+	return tal_count(*added_ins) != 0 ||
+		tal_count(*rm_ins) != 0 ||
+		tal_count(*added_outs) != 0 ||
+		tal_count(*rm_outs) != 0;
+}
+
+void psbt_input_add_serial_id(struct wally_psbt_input *input,
+			      u16 serial_id)
+{
+	u8 *key = psbt_make_key(tmpctx, PSBT_TYPE_SERIAL_ID, NULL);
+	psbt_input_add_unknown(input, key, &serial_id, sizeof(serial_id));
+}
+
+
+void psbt_output_add_serial_id(struct wally_psbt_output *output,
+			       u16 serial_id)
+{
+	u8 *key = psbt_make_key(tmpctx, PSBT_TYPE_SERIAL_ID, NULL);
+	psbt_output_add_unknown(output, key, &serial_id, sizeof(serial_id));
+}
+
+bool psbt_has_serial_input(struct wally_psbt *psbt, u16 serial_id)
+{
+	for (size_t i = 0; i < psbt->num_inputs; i++) {
+		u16 in_serial;
+		if (!psbt_get_serial_id(&psbt->inputs[i].unknowns, &in_serial))
+			continue;
+		if (in_serial == serial_id)
+			return true;
+	}
+	return false;
+}
+
+bool psbt_has_serial_output(struct wally_psbt *psbt, u16 serial_id)
+{
+	for (size_t i = 0; i < psbt->num_outputs; i++) {
+		u16 out_serial;
+		if (!psbt_get_serial_id(&psbt->outputs[i].unknowns, &out_serial))
+			continue;
+		if (out_serial == serial_id)
+			return true;
+	}
+	return false;
+}
+
+void psbt_input_add_max_witness_len(struct wally_psbt_input *input,
+				    u16 max_witness_len)
+{
+	u8 *key = psbt_make_key(NULL, PSBT_TYPE_MAX_WITNESS_LEN, NULL);
+	psbt_input_add_unknown(input, key, &max_witness_len, sizeof(max_witness_len));
+	tal_free(key);
+}
+
+
+bool psbt_input_get_max_witness_len(struct wally_psbt_input *input,
+				    u16 *max_witness_len)
+{
+	size_t value_len;
+	void *result = psbt_get_lightning(&input->unknowns,
+					  PSBT_TYPE_MAX_WITNESS_LEN,
+					  &value_len);
+	if (!result)
+		return false;
+
+	if (value_len != sizeof(*max_witness_len))
+		return false;
+
+	memcpy(max_witness_len, result, value_len);
+	return true;
+}
+
+bool psbt_has_required_fields(struct wally_psbt *psbt)
+{
+	u16 max_witness, serial_id;
+	for (size_t i = 0; i < psbt->num_inputs; i++) {
+		struct wally_psbt_input *input = &psbt->inputs[i];
+
+		if (!psbt_get_serial_id(&input->unknowns, &serial_id))
+			return false;
+
+		/* Inputs had also better have their max_witness_lens
+		 * filled in! */
+		if (!psbt_input_get_max_witness_len(input, &max_witness))
+			return false;
+
+		/* Required because we send the full tx over the wire now */
+		if (!input->utxo)
+			return false;
+
+		/* If is P2SH, redeemscript must be present */
+		const u8 *outscript =
+			wally_tx_output_get_script(tmpctx,
+				&input->utxo->outputs[psbt->tx->inputs[i].index]);
+		if (is_p2sh(outscript, NULL) && input->redeem_script_len == 0)
+			return false;
+
+	}
+
+	for (size_t i = 0; i < psbt->num_outputs; i++) {
+		if (!psbt_get_serial_id(&psbt->outputs[i].unknowns, &serial_id))
+			return false;
+	}
+
+	return true;
+}
--- a/common/psbt_open.h
+++ b/common/psbt_open.h
@ -0,0 +1,145 @@
+#ifndef LIGHTNING_COMMON_PSBT_OPEN_H
+#define LIGHTNING_COMMON_PSBT_OPEN_H
+#include "config.h"
+#include <ccan/short_types/short_types.h>
+#include <ccan/tal/tal.h>
+#include <stdbool.h>
+#include <wally_psbt.h>
+#include <wally_transaction.h>
+
+struct wally_tx_input;
+struct wally_tx_output;
+struct wally_psbt;
+struct wally_psbt_input;
+struct wally_psbt_output;
+struct wally_map;
+
+struct input_set {
+	struct wally_tx_input tx_input;
+	struct wally_psbt_input input;
+};
+
+struct output_set {
+	struct wally_tx_output tx_output;
+	struct wally_psbt_output output;
+};
+
+#define PSBT_TYPE_SERIAL_ID 0x01
+#define PSBT_TYPE_MAX_WITNESS_LEN 0x02
+
+/* psbt_get_serial_id - Returns the serial_id from an unknowns map
+ *
+ * @map - the map to find the serial id entry within
+ * @serial_id - found serial_id
+ *
+ * Returns false if serial_id is not present
+ */
+WARN_UNUSED_RESULT bool psbt_get_serial_id(const struct wally_map *map,
+					   u16 *serial_id);
+
+/* psbt_sort_by_serial_id - Sort PSBT by serial_ids
+ *
+ * MUST have a serial_id on every input/output.
+ *
+ * @psbt - psbt to sort
+ */
+void psbt_sort_by_serial_id(struct wally_psbt *psbt);
+
+/* psbt_has_diff - Returns set of diffs btw orig + new psbt
+ *
+ * All inputs+outputs MUST have a serial_id field present before
+ * calling this.
+ *
+ * @ctx - allocation context for returned diffsets
+ * @orig - original psbt
+ * @new - updated psbt
+ * @added_ins - inputs added {new}
+ * @rm_ins - inputs removed {orig}
+ * @added_outs - outputs added {new}
+ * @rm_outs - outputs removed {orig}
+ *
+ * Note that the input + output data returned in the diff sets
+ * contain references to the originating PSBT; they are not copies.
+ *
+ * Returns true if changes are found.
+ */
+bool psbt_has_diff(const tal_t *ctx,
+		   struct wally_psbt *orig,
+		   struct wally_psbt *new,
+		   struct input_set **added_ins,
+		   struct input_set **rm_ins,
+		   struct output_set **added_outs,
+		   struct output_set **rm_outs);
+
+/* psbt_input_add_serial_id - Adds a serial id to given input
+ *
+ * @input - to add serial_id to
+ * @serial_id - to add
+ */
+void psbt_input_add_serial_id(struct wally_psbt_input *input,
+			       u16 serial_id);
+/* psbt_output_add_serial_id - Adds a serial id to given output
+ *
+ * @output - to add serial_id to
+ * @serial_id - to add
+ */
+void psbt_output_add_serial_id(struct wally_psbt_output *output,
+			       u16 serial_id);
+
+/* psbt_sort_by_serial_id - Sorts the inputs + outputs by serial_id
+ *
+ * Requires every input/output to have a serial_id entry.
+ *
+ * @psbt - psbt to sort inputs/outputs
+ */
+void psbt_sort_by_serial_id(struct wally_psbt *psbt);
+
+/* psbt_has_serial_input - Checks inputs for provided serial_id
+ *
+ * @psbt - psbt's inputs to check
+ * @serial_id - id to look for
+ * Returns true if serial_id found.
+ */
+WARN_UNUSED_RESULT bool
+psbt_has_serial_input(struct wally_psbt *psbt, u16 serial_id);
+
+/* psbt_has_serial_output - Checks outputs for provided serial_id
+ *
+ * @psbt - psbt's outputs to check
+ * @serial_id - id to look for
+ * Returns true if serial_id found.
+ */
+WARN_UNUSED_RESULT bool
+psbt_has_serial_output(struct wally_psbt *psbt, u16 serial_id);
+
+/* psbt_input_add_max_witness_len - Put a max witness len on a thing
+ *
+ * @input - input to add max-witness-len to
+ * @max_witness_len - value
+ */
+void psbt_input_add_max_witness_len(struct wally_psbt_input *input,
+				    u16 max_witness_len);
+
+/* psbt_input_get_max_witness_len - Get the max_witness_len
+ *
+ * @input - psbt input to look for max witness len on
+ * @max_witness_len - found length
+ *
+ * Returns false if key not present */
+WARN_UNUSED_RESULT bool
+psbt_input_get_max_witness_len(struct wally_psbt_input *input,
+			       u16 *max_witness_len);
+
+/* psbt_has_required_fields - Validates psbt field completion
+ *
+ * Required fields are:
+ * - a serial_id; input+output
+ * - a prev_tx; input,non_witness_utxo
+ * - redeemscript; input,iff is P2SH-P2W*
+ * @psbt - psbt to validate
+ *
+ * Returns true if all required fields are present
+ */
+bool psbt_has_required_fields(struct wally_psbt *psbt);
+
+#endif /* LIGHTNING_COMMON_PSBT_OPEN_H */