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110 lines
2.4 KiB
110 lines
2.4 KiB
#include "permute_tx.h"
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#include <stdbool.h>
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#include <string.h>
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static bool input_better(const struct bitcoin_tx_input *a,
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const struct bitcoin_tx_input *b)
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{
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int cmp;
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cmp = memcmp(&a->txid, &b->txid, sizeof(a->txid));
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if (cmp != 0)
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return cmp < 0;
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if (a->index != b->index)
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return a->index < b->index;
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/* These shouldn't happen, but let's get a canonical order anyway. */
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if (tal_len(a->script) != tal_len(b->script))
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return tal_len(a->script) < tal_len(b->script);
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cmp = memcmp(a->script, b->script, tal_len(a->script));
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if (cmp != 0)
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return cmp < 0;
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return a->sequence_number < b->sequence_number;
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}
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static size_t find_best_in(struct bitcoin_tx_input *inputs, 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 (input_better(&inputs[i], &inputs[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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static void swap_inputs(struct bitcoin_tx_input *inputs, size_t i1, size_t i2)
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{
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struct bitcoin_tx_input tmpinput;
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tmpinput = inputs[i1];
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inputs[i1] = inputs[i2];
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inputs[i2] = tmpinput;
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}
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void permute_inputs(struct bitcoin_tx_input *inputs, size_t num_inputs)
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{
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size_t i;
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/* Now do a dumb sort (num_inputs is small). */
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for (i = 0; i < num_inputs; i++) {
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/* Swap best into first place. */
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swap_inputs(inputs,
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i, i + find_best_in(inputs + i, num_inputs - i));
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}
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}
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static void swap_outputs(struct bitcoin_tx_output *outputs,
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size_t i1, size_t i2)
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{
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struct bitcoin_tx_output tmpoutput;
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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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}
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static bool output_better(const struct bitcoin_tx_output *a,
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const struct bitcoin_tx_output *b)
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{
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size_t len;
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int ret;
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if (a->amount != b->amount)
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return a->amount < b->amount;
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/* Lexographic sort. */
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if (tal_len(a->script) < tal_len(b->script))
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len = tal_len(a->script);
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else
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len = tal_len(b->script);
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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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return tal_len(a->script) < tal_len(b->script);
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}
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static size_t find_best_out(struct bitcoin_tx_output *outputs, 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], &outputs[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_output *outputs, size_t num_outputs)
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{
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size_t i;
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/* Now do a dumb sort (num_outputs is small). */
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for (i = 0; i < num_outputs; i++) {
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/* Swap best into first place. */
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swap_outputs(outputs,
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i, i + find_best_out(outputs + i, num_outputs - i));
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}
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}
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