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114 lines
2.4 KiB
C
114 lines
2.4 KiB
C
#include "config.h"
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#include <common/permute_tx.h>
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#include <wally_psbt.h>
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static void swap_wally_outputs(struct wally_tx_output *outputs,
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struct wally_tx_output *psbt_global_outs,
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struct wally_psbt_output *psbt_outs,
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const void **map, u32 *cltvs,
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size_t i1, size_t i2)
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{
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struct wally_tx_output tmpoutput;
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struct wally_psbt_output tmppsbtout;
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if (i1 == i2)
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return;
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tmpoutput = outputs[i1];
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outputs[i1] = outputs[i2];
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outputs[i2] = tmpoutput;
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/* For the PSBT, we swap the psbt outputs and
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* the global tx's outputs */
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tmpoutput = psbt_global_outs[i1];
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psbt_global_outs[i1] = psbt_global_outs[i2];
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psbt_global_outs[i2] = tmpoutput;
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tmppsbtout = psbt_outs[i1];
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psbt_outs[i1] = psbt_outs[i2];
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psbt_outs[i2] = tmppsbtout;
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if (map) {
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const void *tmp = map[i1];
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map[i1] = map[i2];
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map[i2] = tmp;
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}
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if (cltvs) {
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u32 tmp = cltvs[i1];
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cltvs[i1] = cltvs[i2];
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cltvs[i2] = tmp;
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}
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}
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static bool output_better(const struct wally_tx_output *a, u32 cltv_a,
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const struct wally_tx_output *b, u32 cltv_b)
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{
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size_t len, lena, lenb;
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int ret;
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if (a->satoshi != b->satoshi)
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return a->satoshi < b->satoshi;
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/* Lexicographical sort. */
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lena = a->script_len;
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lenb = b->script_len;
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if (lena < lenb)
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len = lena;
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else
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len = lenb;
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ret = memcmp(a->script, b->script, len);
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if (ret != 0)
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return ret < 0;
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if (lena != lenb)
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return lena < lenb;
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return cltv_a < cltv_b;
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}
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static u32 cltv_of(const u32 *cltvs, size_t idx)
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{
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if (!cltvs)
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return 0;
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return cltvs[idx];
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}
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static size_t find_best_out(struct wally_tx_output *outputs, const u32 *cltvs,
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size_t num)
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{
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size_t i, best = 0;
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for (i = 1; i < num; i++) {
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if (output_better(&outputs[i], cltv_of(cltvs, i),
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&outputs[best], cltv_of(cltvs, best)))
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best = i;
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}
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return best;
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}
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void permute_outputs(struct bitcoin_tx *tx, u32 *cltvs, const void **map)
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{
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size_t i, best_pos;
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struct wally_tx_output *outputs = tx->wtx->outputs;
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size_t num_outputs = tx->wtx->num_outputs;
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/* We can't permute nothing! */
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if (num_outputs == 0)
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return;
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/* Now do a dumb sort (num_outputs is small). */
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for (i = 0; i < num_outputs - 1; i++) {
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best_pos =
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i + find_best_out(outputs + i, cltvs ? cltvs + i : NULL,
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num_outputs - i);
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/* Swap best into first place. */
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swap_wally_outputs(tx->wtx->outputs,
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tx->psbt->tx->outputs,
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tx->psbt->outputs,
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map, cltvs, i, best_pos);
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}
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}
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