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commit_tx: expose more internal functions.

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without having to build it, which is needed for limit enforcement.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2017-02-21 15:15:28 +10:30
parent e8e96e67d0
commit 9284819f68
3 changed files with 102 additions and 59 deletions
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142
lightningd/commit_tx.c
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@@ -73,13 +73,11 @@ u64 htlc_success_fee(u64 feerate_per_kw)
return feerate_per_kw * 673 / 1000;
}
static const struct htlc **untrimmed(const tal_t *ctx,
const struct htlc **htlcs,
enum side side,
u64 htlc_fee, u64 dust_limit_satoshis)
static bool trim(const struct htlc *htlc,
u64 feerate_per_kw, u64 dust_limit_satoshis,
enum side side)
{
const struct htlc **arr;
size_t i, n;
u64 htlc_fee;
/* BOLT #3:
*
@@ -88,6 +86,10 @@ static const struct htlc **untrimmed(const tal_t *ctx,
* owner, the commitment transaction MUST NOT contain that output,
* otherwise it MUST be generated as specified in [Offered HTLC
* Outputs](#offered-htlc-outputs).
*/
if (htlc_owner(htlc) == side)
htlc_fee = htlc_timeout_fee(feerate_per_kw);
/* BOLT #3:
*
* For every received HTLC, if the HTLC amount minus the HTLC-success
* fee would be less than `dust-limit-satoshis` set by the transaction
@@ -95,22 +97,25 @@ static const struct htlc **untrimmed(const tal_t *ctx,
* otherwise it MUST be generated as specified in [Received HTLC
* Outputs](#received-htlc-outputs).
*/
arr = tal_arr(ctx, const struct htlc *, tal_count(htlcs));
for (i = n = 0; i < tal_count(htlcs); i++) {
if (htlc_owner(htlcs[i]) != side)
continue;
if (htlcs[i]->msatoshi / 1000 < dust_limit_satoshis + htlc_fee)
continue;
arr[n++] = htlcs[i];
}
else
htlc_fee = htlc_success_fee(feerate_per_kw);
assert(n <= tal_count(arr));
tal_resize(&arr, n);
return arr;
return htlc->msatoshi / 1000 < dust_limit_satoshis + htlc_fee;
}
static u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs)
size_t commit_tx_num_untrimmed(const struct htlc **htlcs,
u64 feerate_per_kw, u64 dust_limit_satoshis,
enum side side)
{
size_t i, n;
for (i = n = 0; i < tal_count(htlcs); i++)
n += !trim(htlcs[i], feerate_per_kw, dust_limit_satoshis, side);
return n;
}
u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs)
{
u64 weight;
@@ -139,6 +144,38 @@ static u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs)
return feerate_per_kw * weight / 1000;
}
static void add_offered_htlc_out(struct bitcoin_tx *tx, size_t n,
const struct htlc *htlc,
const struct pubkey *selfkey,
const struct pubkey *otherkey)
{
u8 *wscript = bitcoin_wscript_htlc_offer(tx,
selfkey, otherkey,
&htlc->rhash);
tx->output[n].amount = htlc->msatoshi / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
SUPERVERBOSE("# HTLC offered amount %"PRIu64" wscript %s\n",
tx->output[n].amount, tal_hex(wscript, wscript));
tal_free(wscript);
}
static void add_received_htlc_out(struct bitcoin_tx *tx, size_t n,
const struct htlc *htlc,
const struct pubkey *selfkey,
const struct pubkey *otherkey)
{
u8 *wscript = bitcoin_wscript_htlc_receive(tx,
&htlc->expiry,
selfkey, otherkey,
&htlc->rhash);
tx->output[n].amount = htlc->msatoshi / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx->output, wscript);
SUPERVERBOSE("# HTLC received amount %"PRIu64" wscript %s\n",
tx->output[n].amount,
tal_hex(wscript, wscript));
tal_free(wscript);
}
struct bitcoin_tx *commit_tx(const tal_t *ctx,
const struct sha256_double *funding_txid,
unsigned int funding_txout,
@@ -159,10 +196,9 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
enum side side)
{
const tal_t *tmpctx = tal_tmpctx(ctx);
const struct htlc **offered, **received;
u64 base_fee_msat;
struct bitcoin_tx *tx;
size_t i, n;
size_t i, n, untrimmed;
assert(self_pay_msat + other_pay_msat <= funding_satoshis * 1000);
@@ -171,22 +207,16 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
* 1. Calculate which committed HTLCs need to be trimmed (see
* [Trimmed Outputs](#trimmed-outputs)).
*/
offered = untrimmed(tmpctx, htlcs, side,
htlc_timeout_fee(feerate_per_kw),
dust_limit_satoshis);
received = untrimmed(tmpctx, htlcs, !side,
htlc_success_fee(feerate_per_kw),
dust_limit_satoshis);
untrimmed = commit_tx_num_untrimmed(htlcs,
feerate_per_kw,
dust_limit_satoshis, side);
/* BOLT #3:
*
* 2. Calculate the base [commitment transaction
* fee](#fee-calculation).
*/
base_fee_msat = commit_tx_base_fee(feerate_per_kw,
tal_count(offered)
+ tal_count(received))
* 1000;
base_fee_msat = commit_tx_base_fee(feerate_per_kw, untrimmed) * 1000;
SUPERVERBOSE("# base commitment transaction fee = %"PRIu64"\n",
base_fee_msat / 1000);
@@ -200,45 +230,41 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
&self_pay_msat, &other_pay_msat);
/* Worst-case sizing: both to-local and to-remote outputs. */
tx = bitcoin_tx(ctx, 1, tal_count(offered) + tal_count(received) + 2);
tx = bitcoin_tx(ctx, 1, untrimmed + 2);
/* We keep track of which outputs have which HTLCs */
*htlcmap = tal_arr(tx, const struct htlc *, tal_count(tx->output));
/* This could be done in a single loop, but we follow the BOLT
* literally to make comments in test vectors clearer. */
n = 0;
/* BOLT #3:
*
* 3. For every offered HTLC, if it is not trimmed, add an [offered
* HTLC output](#offered-htlc-outputs).
* 3. For every offered HTLC, if it is not trimmed, add an
* [offered HTLC output](#offered-htlc-outputs).
*/
n = 0;
for (i = 0; i < tal_count(offered); i++, n++) {
u8 *wscript = bitcoin_wscript_htlc_offer(tmpctx,
selfkey, otherkey,
&offered[i]->rhash);
tx->output[n].amount = offered[i]->msatoshi / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
(*htlcmap)[n] = offered[i];
SUPERVERBOSE("# HTLC offered amount %"PRIu64" wscript %s\n",
tx->output[n].amount,
tal_hex(tmpctx, wscript));
for (i = 0; i < tal_count(htlcs); i++) {
if (htlc_owner(htlcs[i]) != side)
continue;
if (trim(htlcs[i], feerate_per_kw, dust_limit_satoshis, side))
continue;
add_offered_htlc_out(tx, n, htlcs[i], selfkey, otherkey);
(*htlcmap)[n++] = htlcs[i];
}
/* BOLT #3:
*
* 4. For every received HTLC, if it is not trimmed, add an [received
* HTLC output](#received-htlc-outputs).
* 4. For every received HTLC, if it is not trimmed, add an
* [received HTLC output](#received-htlc-outputs).
*/
for (i = 0; i < tal_count(received); i++, n++) {
u8 *wscript = bitcoin_wscript_htlc_receive(tmpctx,
&received[i]->expiry,
selfkey, otherkey,
&received[i]->rhash);
tx->output[n].amount = received[i]->msatoshi / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
(*htlcmap)[n] = received[i];
SUPERVERBOSE("# HTLC received amount %"PRIu64" wscript %s\n",
tx->output[n].amount,
tal_hex(tmpctx, wscript));
for (i = 0; i < tal_count(htlcs); i++) {
if (htlc_owner(htlcs[i]) == side)
continue;
if (trim(htlcs[i], feerate_per_kw, dust_limit_satoshis, side))
continue;
add_received_htlc_out(tx, n, htlcs[i],selfkey, otherkey);
(*htlcmap)[n++] = htlcs[i];
}
/* BOLT #3: