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#include "permute_tx.h"
#include <stdbool.h>
#include <string.h>
static bool input_better(const struct bitcoin_tx_input *a,
const struct bitcoin_tx_input *b)
{
int cmp;
cmp = memcmp(&a->txid, &b->txid, sizeof(a->txid));
if (cmp != 0)
return cmp < 0;
if (a->index != b->index)
return a->index < b->index;
/* These shouldn't happen, but let's get a canonical order anyway. */
if (tal_count(a->script) != tal_count(b->script))
return tal_count(a->script) < tal_count(b->script);
cmp = memcmp(a->script, b->script, tal_count(a->script));
if (cmp != 0)
return cmp < 0;
return a->sequence_number < b->sequence_number;
}
static size_t find_best_in(struct bitcoin_tx_input *inputs, size_t num)
{
size_t i, best = 0;
for (i = 1; i < num; i++) {
if (input_better(&inputs[i], &inputs[best]))
best = i;
}
return best;
}
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;
if (i1 == i2)
return;
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,
const void **map)
{
size_t i;
size_t num_inputs = tal_count(inputs);
/* We can't permute nothing! */
if (num_inputs == 0)
return;
/* Now do a dumb sort (num_inputs is small). */
for (i = 0; i < num_inputs-1; i++) {
/* Swap best into first place. */
swap_inputs(inputs, map,
i, i + find_best_in(inputs + i, num_inputs - i));
}
}
static void swap_outputs(struct bitcoin_tx_output *outputs,
const void **map,
u32 *cltvs,
size_t i1, size_t i2)
{
struct bitcoin_tx_output tmpoutput;
if (i1 == i2)
return;
tmpoutput = outputs[i1];
outputs[i1] = outputs[i2];
outputs[i2] = tmpoutput;
if (map) {
const void *tmp = map[i1];
map[i1] = map[i2];
map[i2] = tmp;
}
if (cltvs) {
u32 tmp = cltvs[i1];
cltvs[i1] = cltvs[i2];
cltvs[i2] = tmp;
}
}
static bool output_better(const struct bitcoin_tx_output *a,
u32 cltv_a,
const struct bitcoin_tx_output *b,
u32 cltv_b)
{
size_t len, lena, lenb;
int ret;
if (a->amount != b->amount)
return a->amount < b->amount;
/* Lexicographical sort. */
lena = tal_count(a->script);
lenb = tal_count(b->script);
if (lena < lenb)
len = lena;
else
len = lenb;
ret = memcmp(a->script, b->script, len);
if (ret != 0)
return ret < 0;
if (lena != lenb)
return lena < lenb;
return cltv_a < cltv_b;
}
static u32 cltv_of(const u32 *cltvs, size_t idx)
{
if (!cltvs)
return 0;
return cltvs[idx];
}
static size_t find_best_out(struct bitcoin_tx_output *outputs,
const u32 *cltvs,
size_t num)
{
size_t i, best = 0;
for (i = 1; i < num; i++) {
if (output_better(&outputs[i], cltv_of(cltvs, i),
&outputs[best], cltv_of(cltvs, best)))
best = i;
}
return best;
}
void permute_outputs(struct bitcoin_tx_output *outputs,
u32 *cltvs,
const void **map)
{
size_t i;
size_t num_outputs = tal_count(outputs);
/* We can't permute nothing! */
if (num_outputs == 0)
return;
/* Now do a dumb sort (num_outputs is small). */
for (i = 0; i < num_outputs-1; i++) {
/* Swap best into first place. */
swap_outputs(outputs, map, cltvs,
i, i + find_best_out(outputs + i,
cltvs ? cltvs + i : NULL,
num_outputs - i));
}
}