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#include <assert.h>
#include <bitcoin/block.h>
#include <bitcoin/pullpush.h>
#include <bitcoin/tx.h>
#include <ccan/cast/cast.h>
#include <ccan/crypto/sha256/sha256.h>
#include <ccan/endian/endian.h>
#include <ccan/mem/mem.h>
#include <ccan/read_write_all/read_write_all.h>
#include <ccan/str/hex/hex.h>
#include <common/type_to_string.h>
#include <stdio.h>
#include <wire/wire.h>
#define SEGREGATED_WITNESS_FLAG 0x1
int bitcoin_tx_add_output(struct bitcoin_tx *tx, const u8 *script,
struct amount_sat amount)
{
size_t i = tx->wtx->num_outputs;
struct wally_tx_output *output;
int ret;
u64 satoshis = amount.satoshis; /* Raw: low-level helper */
const struct chainparams *chainparams = tx->chainparams;
assert(i < tx->wtx->outputs_allocation_len);
assert(tx->wtx != NULL);
assert(chainparams);
if (chainparams->is_elements) {
u8 value[9];
ret = wally_tx_confidential_value_from_satoshi(satoshis, value,
sizeof(value));
assert(ret == WALLY_OK);
ret = wally_tx_elements_output_init_alloc(
script, tal_bytelen(script), chainparams->fee_asset_tag, 33,
value, sizeof(value), NULL, 0, NULL, 0, NULL, 0, &output);
assert(ret == WALLY_OK);
/* Cheat a bit by also setting the numeric satoshi value,
* otherwise we end up converting a number of times */
output->satoshi = satoshis;
} else {
ret = wally_tx_output_init_alloc(satoshis, script,
tal_bytelen(script), &output);
assert(ret == WALLY_OK);
}
ret = wally_tx_add_output(tx->wtx, output);
assert(ret == WALLY_OK);
wally_tx_output_free(output);
bitcoin_tx_output_set_amount(tx, i, amount);
return i;
}
int bitcoin_tx_add_multi_outputs(struct bitcoin_tx *tx,
struct bitcoin_tx_output **outputs)
{
for (size_t j = 0; j < tal_count(outputs); j++)
bitcoin_tx_add_output(tx, outputs[j]->script,
outputs[j]->amount);
return tx->wtx->num_outputs;
}
static bool elements_tx_output_is_fee(const struct bitcoin_tx *tx, int outnum)
{
assert(outnum < tx->wtx->num_outputs);
return chainparams->is_elements &&
tx->wtx->outputs[outnum].script_len == 0;
}
/**
* Compute how much fee we are actually sending with this transaction.
*/
static struct amount_sat bitcoin_tx_compute_fee(const struct bitcoin_tx *tx)
{
struct amount_sat fee = AMOUNT_SAT(0), value;
struct amount_asset asset;
bool ok;
for (size_t i = 0; i < tal_count(tx->input_amounts); i++) {
value.satoshis = tx->input_amounts[i]->satoshis; /* Raw: fee computation */
ok = amount_sat_add(&fee, fee, value);
assert(ok);
}
for (size_t i = 0; i < tx->wtx->num_outputs; i++) {
asset = bitcoin_tx_output_get_amount(tx, i);
if (elements_tx_output_is_fee(tx, i) ||
!amount_asset_is_main(&asset))
continue;
value = amount_asset_to_sat(&asset);
ok = amount_sat_sub(&fee, fee, value);
assert(ok);
}
return fee;
}
/**
* Add an explicit fee output if necessary.
*
* An explicit fee output is only necessary if we are using an elements
* transaction, and we have a non-zero fee. This method may be called multiple
* times.
*
* Returns the position of the fee output, or -1 in the case of non-elements
* transactions.
*/
static int elements_tx_add_fee_output(struct bitcoin_tx *tx)
{
struct amount_sat fee = bitcoin_tx_compute_fee(tx);
int pos;
struct witscript *w;
/* If we aren't using elements, we don't add explicit fee outputs */
if (!chainparams->is_elements || amount_sat_eq(fee, AMOUNT_SAT(0)))
return -1;
/* Try to find any existing fee output */
for (pos = 0; pos < tx->wtx->num_outputs; pos++) {
if (elements_tx_output_is_fee(tx, pos))
break;
}
if (pos == tx->wtx->num_outputs) {
w = tal(tx->output_witscripts, struct witscript);
w->ptr = tal_arr(w, u8, 0);
/* Make sure we have a place to stash the witness script in. */
if (tal_count(tx->output_witscripts) < pos + 1) {
tal_resize(&tx->output_witscripts, pos + 1);
}
tx->output_witscripts[pos] = w;
return bitcoin_tx_add_output(tx, NULL, fee);
} else {
bitcoin_tx_output_set_amount(tx, pos, fee);
return pos;
}
}
int bitcoin_tx_add_input(struct bitcoin_tx *tx, const struct bitcoin_txid *txid,
u32 outnum, u32 sequence,
struct amount_sat amount, u8 *script)
{
struct wally_tx_input *input;
size_t i;
assert(tx->wtx != NULL);
i = tx->wtx->num_inputs;
wally_tx_input_init_alloc(txid->shad.sha.u.u8,
sizeof(struct bitcoin_txid), outnum, sequence,
script, tal_bytelen(script),
NULL /* Empty witness stack */, &input);
input->features = chainparams->is_elements ? WALLY_TX_IS_ELEMENTS : 0;
wally_tx_add_input(tx->wtx, input);
wally_tx_input_free(input);
/* Now store the input amount if we know it, so we can sign later */
if (tal_count(tx->input_amounts) < tx->wtx->num_inputs)
tal_resize(&tx->input_amounts, tx->wtx->num_inputs);
tx->input_amounts[i] = tal_free(tx->input_amounts[i]);
tx->input_amounts[i] = tal_dup(tx, struct amount_sat, &amount);
return i;
}
bool bitcoin_tx_check(const struct bitcoin_tx *tx)
{
u8 *newtx;
size_t written;
int flags = WALLY_TX_FLAG_USE_WITNESS;
if (tal_count(tx->input_amounts) != tx->wtx->num_inputs)
return false;
if (tal_count(tx->output_witscripts) != tx->wtx->num_outputs)
return false;
if (wally_tx_get_length(tx->wtx, flags, &written) != WALLY_OK)
return false;
newtx = tal_arr(tmpctx, u8, written);
if (wally_tx_to_bytes(tx->wtx, flags, newtx, written, &written) !=
WALLY_OK)
return false;
if (written != tal_bytelen(newtx))
return false;
return true;
}
void bitcoin_tx_output_set_amount(struct bitcoin_tx *tx, int outnum,
struct amount_sat amount)
{
u64 satoshis = amount.satoshis; /* Raw: low-level helper */
struct wally_tx_output *output = &tx->wtx->outputs[outnum];
assert(outnum < tx->wtx->num_outputs);
if (chainparams->is_elements) {
int ret = wally_tx_confidential_value_from_satoshi(
satoshis, output->value, output->value_len);
assert(ret == WALLY_OK);
} else {
output->satoshi = satoshis;
}
}
const u8 *bitcoin_tx_output_get_script(const tal_t *ctx,
const struct bitcoin_tx *tx, int outnum)
{
const struct wally_tx_output *output;
u8 *res;
assert(outnum < tx->wtx->num_outputs);
output = &tx->wtx->outputs[outnum];
if (output->script == NULL) {
/* This can happen for coinbase transactions and pegin
* transactions */
return NULL;
}
res = tal_arr(ctx, u8, output->script_len);
memcpy(res, output->script, output->script_len);
return res;
}
/* FIXME(cdecker) Make the caller pass in a reference to amount_asset, and
* return false if unintelligible/encrypted. (WARN UNUSED). */
struct amount_asset bitcoin_tx_output_get_amount(const struct bitcoin_tx *tx,
int outnum)
{
struct amount_asset amount;
struct wally_tx_output *output;
be64 raw;
assert(tx->chainparams);
assert(outnum < tx->wtx->num_outputs);
output = &tx->wtx->outputs[outnum];
if (chainparams->is_elements) {
assert(output->asset_len == sizeof(amount.asset));
memcpy(&amount.asset, output->asset, sizeof(amount.asset));
/* We currently only support explicit value asset tags, others
* are confidential, so don't even try to assign a value to
* it. */
if (output->asset[0] == 0x01) {
memcpy(&raw, output->value + 1, sizeof(raw));
amount.value = be64_to_cpu(raw);
} else {
amount.value = 0;
}
} else {
/* Do not assign amount.asset, we should never touch it in
* non-elements scenarios. */
amount.value = tx->wtx->outputs[outnum].satoshi;
}
return amount;
}
void bitcoin_tx_input_set_witness(struct bitcoin_tx *tx, int innum,
u8 **witness)
{
struct wally_tx_witness_stack *stack = NULL;
size_t stack_size = tal_count(witness);
/* Free any lingering witness */
if (witness) {
wally_tx_witness_stack_init_alloc(stack_size, &stack);
for (size_t i = 0; i < stack_size; i++)
wally_tx_witness_stack_add(stack, witness[i],
tal_bytelen(witness[i]));
}
wally_tx_set_input_witness(tx->wtx, innum, stack);
if (stack)
wally_tx_witness_stack_free(stack);
if (taken(witness))
tal_free(witness);
}
void bitcoin_tx_input_set_script(struct bitcoin_tx *tx, int innum, u8 *script)
{
wally_tx_set_input_script(tx->wtx, innum, script, tal_bytelen(script));
}
const u8 *bitcoin_tx_input_get_witness(const tal_t *ctx,
const struct bitcoin_tx *tx, int innum,
int witnum)
{
const u8 *witness_item;
struct wally_tx_witness_item *item;
assert(innum < tx->wtx->num_inputs);
assert(witnum < tx->wtx->inputs[innum].witness->num_items);
item = &tx->wtx->inputs[innum].witness->items[witnum];
witness_item =
tal_dup_arr(ctx, u8, item->witness, item->witness_len, 0);
return witness_item;
}
void bitcoin_tx_input_get_txid(const struct bitcoin_tx *tx, int innum,
struct bitcoin_txid *out)
{
assert(innum < tx->wtx->num_inputs);
assert(sizeof(struct bitcoin_txid) ==
sizeof(tx->wtx->inputs[innum].txhash));
memcpy(out, tx->wtx->inputs[innum].txhash, sizeof(struct bitcoin_txid));
}
/* BIP144:
* If the witness is empty, the old serialization format should be used. */
static bool uses_witness(const struct bitcoin_tx *tx)
{
size_t i;
for (i = 0; i < tx->wtx->num_inputs; i++) {
if (tx->wtx->inputs[i].witness)
return true;
}
return false;
}
/* For signing, we ignore input scripts on other inputs, and pretend
* the current input has a certain script: this is indicated by a
* non-NULL override_script.
*
* For this (and other signing weirdness like SIGHASH_SINGLE), we
* also need the current input being signed; that's in input_num.
* We also need sighash_type.
*/
static void push_tx(const struct bitcoin_tx *tx,
const u8 *override_script,
size_t input_num,
void (*push)(const void *, size_t, void *), void *pushp,
bool bip144)
{
int res;
size_t len, written;
u8 *serialized;;
u8 flag = 0;
if (bip144 && uses_witness(tx))
flag |= WALLY_TX_FLAG_USE_WITNESS;
res = wally_tx_get_length(tx->wtx, flag, &len);
assert(res == WALLY_OK);
serialized = tal_arr(tmpctx, u8, len);
res = wally_tx_to_bytes(tx->wtx, flag, serialized, len, &written);
assert(res == WALLY_OK);
assert(len == written);
push(serialized, len, pushp);
tal_free(serialized);
}
static void push_sha(const void *data, size_t len, void *shactx_)
{
struct sha256_ctx *ctx = shactx_;
sha256_update(ctx, memcheck(data, len), len);
}
static void push_linearize(const void *data, size_t len, void *pptr_)
{
u8 **pptr = pptr_;
size_t oldsize = tal_count(*pptr);
tal_resize(pptr, oldsize + len);
memcpy(*pptr + oldsize, memcheck(data, len), len);
}
u8 *linearize_tx(const tal_t *ctx, const struct bitcoin_tx *tx)
{
u8 *arr = tal_arr(ctx, u8, 0);
push_tx(tx, NULL, 0, push_linearize, &arr, true);
return arr;
}
size_t bitcoin_tx_weight(const struct bitcoin_tx *tx)
{
size_t weight;
int ret = wally_tx_get_weight(tx->wtx, &weight);
assert(ret == WALLY_OK);
return weight;
}
void bitcoin_txid(const struct bitcoin_tx *tx, struct bitcoin_txid *txid)
{
struct sha256_ctx ctx = SHA256_INIT;
/* For TXID, we never use extended form. */
push_tx(tx, NULL, 0, push_sha, &ctx, false);
sha256_double_done(&ctx, &txid->shad);
}
/* Use the bitcoin_tx destructor to also free the wally_tx */
static void bitcoin_tx_destroy(struct bitcoin_tx *tx)
{
wally_tx_free(tx->wtx);
}
struct bitcoin_tx *bitcoin_tx(const tal_t *ctx,
const struct chainparams *chainparams,
varint_t input_count, varint_t output_count,
u32 nlocktime)
{
struct bitcoin_tx *tx = tal(ctx, struct bitcoin_tx);
assert(chainparams);
/* If we are constructing an elements transaction we need to
* explicitly add the fee as an extra output. So allocate one more
* than the outputs we need internally. */
if (chainparams->is_elements)
output_count += 1;
wally_tx_init_alloc(WALLY_TX_VERSION_2, 0, input_count, output_count,
&tx->wtx);
tal_add_destructor(tx, bitcoin_tx_destroy);
tx->input_amounts = tal_arrz(tx, struct amount_sat*, input_count);
tx->wtx->locktime = nlocktime;
tx->wtx->version = 2;
tx->output_witscripts = tal_arrz(tx, struct witscript*, output_count);
tx->chainparams = chainparams;
return tx;
}
void bitcoin_tx_finalize(struct bitcoin_tx *tx)
{
size_t num_outputs, num_inputs;
elements_tx_add_fee_output(tx);
num_outputs = tx->wtx->num_outputs;
tal_resize(&(tx->output_witscripts), num_outputs);
num_inputs = tx->wtx->num_inputs;
tal_resize(&tx->input_amounts, num_inputs);
assert(bitcoin_tx_check(tx));
}
struct bitcoin_tx *pull_bitcoin_tx(const tal_t *ctx, const u8 **cursor,
size_t *max)
{
size_t wsize;
int flags = WALLY_TX_FLAG_USE_WITNESS;
struct bitcoin_tx *tx = tal(ctx, struct bitcoin_tx);
if (chainparams->is_elements)
flags |= WALLY_TX_FLAG_USE_ELEMENTS;
if (wally_tx_from_bytes(*cursor, *max, flags, &tx->wtx) != WALLY_OK) {
fromwire_fail(cursor, max);
return tal_free(tx);
}
tal_add_destructor(tx, bitcoin_tx_destroy);
/* For whatever reason the length computation gets upset if we tell it
* that we are using elements. It wants to discover it on its own, NO
* CLUES! (Ms. Doyle)
*
* https://github.com/ElementsProject/libwally-core/issues/139
*/
wally_tx_get_length(tx->wtx, flags & ~WALLY_TX_FLAG_USE_ELEMENTS,
&wsize);
/* We don't know the input amounts yet, so set them all to NULL */
tx->input_amounts =
tal_arrz(tx, struct amount_sat *, tx->wtx->inputs_allocation_len);
tx->chainparams = chainparams;
*cursor += wsize;
*max -= wsize;
return tx;
}
struct bitcoin_tx *bitcoin_tx_from_hex(const tal_t *ctx, const char *hex,
size_t hexlen)
{
const char *end;
u8 *linear_tx;
const u8 *p;
struct bitcoin_tx *tx;
size_t len;
end = memchr(hex, '\n', hexlen);
if (!end)
end = hex + hexlen;
len = hex_data_size(end - hex);
p = linear_tx = tal_arr(ctx, u8, len);
if (!hex_decode(hex, end - hex, linear_tx, len))
goto fail;
tx = pull_bitcoin_tx(ctx, &p, &len);
if (!tx)
goto fail;
if (len)
goto fail_free_tx;
tal_free(linear_tx);
tx->output_witscripts =
tal_arrz(tx, struct witscript *, tx->wtx->num_outputs);
tx->input_amounts =
tal_arrz(tx, struct amount_sat *, tx->wtx->num_inputs);
return tx;
fail_free_tx:
tal_free(tx);
fail:
tal_free(linear_tx);
return NULL;
}
/* <sigh>. Bitcoind represents hashes as little-endian for RPC. */
static void reverse_bytes(u8 *arr, size_t len)
{
unsigned int i;
for (i = 0; i < len / 2; i++) {
unsigned char tmp = arr[i];
arr[i] = arr[len - 1 - i];
arr[len - 1 - i] = tmp;
}
}
bool bitcoin_txid_from_hex(const char *hexstr, size_t hexstr_len,
struct bitcoin_txid *txid)
{
if (!hex_decode(hexstr, hexstr_len, txid, sizeof(*txid)))
return false;
reverse_bytes(txid->shad.sha.u.u8, sizeof(txid->shad.sha.u.u8));
return true;
}
bool bitcoin_txid_to_hex(const struct bitcoin_txid *txid,
char *hexstr, size_t hexstr_len)
{
struct sha256_double rev = txid->shad;
reverse_bytes(rev.sha.u.u8, sizeof(rev.sha.u.u8));
return hex_encode(&rev, sizeof(rev), hexstr, hexstr_len);
}
static char *fmt_bitcoin_tx(const tal_t *ctx, const struct bitcoin_tx *tx)
{
u8 *lin = linearize_tx(ctx, tx);
char *s = tal_hex(ctx, lin);
tal_free(lin);
return s;
}
static char *fmt_bitcoin_txid(const tal_t *ctx, const struct bitcoin_txid *txid)
{
char *hexstr = tal_arr(ctx, char, hex_str_size(sizeof(*txid)));
bitcoin_txid_to_hex(txid, hexstr, hex_str_size(sizeof(*txid)));
return hexstr;
}
REGISTER_TYPE_TO_STRING(bitcoin_tx, fmt_bitcoin_tx);
REGISTER_TYPE_TO_STRING(bitcoin_txid, fmt_bitcoin_txid);