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https://github.com/ElementsProject/lightning.git
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commit_tx: expose more internal functions.
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
parent
e8e96e67d0
commit
9284819f68
@ -73,13 +73,11 @@ u64 htlc_success_fee(u64 feerate_per_kw)
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return feerate_per_kw * 673 / 1000;
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}
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static const struct htlc **untrimmed(const tal_t *ctx,
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const struct htlc **htlcs,
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enum side side,
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u64 htlc_fee, u64 dust_limit_satoshis)
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static bool trim(const struct htlc *htlc,
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u64 feerate_per_kw, u64 dust_limit_satoshis,
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enum side side)
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{
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const struct htlc **arr;
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size_t i, n;
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u64 htlc_fee;
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/* BOLT #3:
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*
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@ -88,6 +86,10 @@ static const struct htlc **untrimmed(const tal_t *ctx,
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* owner, the commitment transaction MUST NOT contain that output,
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* otherwise it MUST be generated as specified in [Offered HTLC
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* Outputs](#offered-htlc-outputs).
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*/
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if (htlc_owner(htlc) == side)
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htlc_fee = htlc_timeout_fee(feerate_per_kw);
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/* BOLT #3:
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*
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* For every received HTLC, if the HTLC amount minus the HTLC-success
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* fee would be less than `dust-limit-satoshis` set by the transaction
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@ -95,22 +97,25 @@ static const struct htlc **untrimmed(const tal_t *ctx,
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* otherwise it MUST be generated as specified in [Received HTLC
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* Outputs](#received-htlc-outputs).
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*/
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arr = tal_arr(ctx, const struct htlc *, tal_count(htlcs));
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for (i = n = 0; i < tal_count(htlcs); i++) {
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if (htlc_owner(htlcs[i]) != side)
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continue;
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if (htlcs[i]->msatoshi / 1000 < dust_limit_satoshis + htlc_fee)
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continue;
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arr[n++] = htlcs[i];
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}
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else
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htlc_fee = htlc_success_fee(feerate_per_kw);
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assert(n <= tal_count(arr));
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tal_resize(&arr, n);
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return arr;
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return htlc->msatoshi / 1000 < dust_limit_satoshis + htlc_fee;
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}
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static u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs)
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size_t commit_tx_num_untrimmed(const struct htlc **htlcs,
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u64 feerate_per_kw, u64 dust_limit_satoshis,
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enum side side)
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{
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size_t i, n;
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for (i = n = 0; i < tal_count(htlcs); i++)
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n += !trim(htlcs[i], feerate_per_kw, dust_limit_satoshis, side);
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return n;
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}
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u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs)
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{
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u64 weight;
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@ -139,6 +144,38 @@ static u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs)
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return feerate_per_kw * weight / 1000;
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}
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static void add_offered_htlc_out(struct bitcoin_tx *tx, size_t n,
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const struct htlc *htlc,
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const struct pubkey *selfkey,
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const struct pubkey *otherkey)
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{
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u8 *wscript = bitcoin_wscript_htlc_offer(tx,
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selfkey, otherkey,
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&htlc->rhash);
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tx->output[n].amount = htlc->msatoshi / 1000;
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tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
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SUPERVERBOSE("# HTLC offered amount %"PRIu64" wscript %s\n",
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tx->output[n].amount, tal_hex(wscript, wscript));
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tal_free(wscript);
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}
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static void add_received_htlc_out(struct bitcoin_tx *tx, size_t n,
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const struct htlc *htlc,
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const struct pubkey *selfkey,
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const struct pubkey *otherkey)
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{
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u8 *wscript = bitcoin_wscript_htlc_receive(tx,
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&htlc->expiry,
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selfkey, otherkey,
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&htlc->rhash);
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tx->output[n].amount = htlc->msatoshi / 1000;
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tx->output[n].script = scriptpubkey_p2wsh(tx->output, wscript);
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SUPERVERBOSE("# HTLC received amount %"PRIu64" wscript %s\n",
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tx->output[n].amount,
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tal_hex(wscript, wscript));
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tal_free(wscript);
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}
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struct bitcoin_tx *commit_tx(const tal_t *ctx,
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const struct sha256_double *funding_txid,
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unsigned int funding_txout,
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@ -159,10 +196,9 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
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enum side side)
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{
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const tal_t *tmpctx = tal_tmpctx(ctx);
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const struct htlc **offered, **received;
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u64 base_fee_msat;
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struct bitcoin_tx *tx;
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size_t i, n;
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size_t i, n, untrimmed;
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assert(self_pay_msat + other_pay_msat <= funding_satoshis * 1000);
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@ -171,22 +207,16 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
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* 1. Calculate which committed HTLCs need to be trimmed (see
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* [Trimmed Outputs](#trimmed-outputs)).
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*/
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offered = untrimmed(tmpctx, htlcs, side,
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htlc_timeout_fee(feerate_per_kw),
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dust_limit_satoshis);
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received = untrimmed(tmpctx, htlcs, !side,
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htlc_success_fee(feerate_per_kw),
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dust_limit_satoshis);
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untrimmed = commit_tx_num_untrimmed(htlcs,
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feerate_per_kw,
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dust_limit_satoshis, side);
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/* BOLT #3:
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*
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* 2. Calculate the base [commitment transaction
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* fee](#fee-calculation).
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*/
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base_fee_msat = commit_tx_base_fee(feerate_per_kw,
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tal_count(offered)
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+ tal_count(received))
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* 1000;
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base_fee_msat = commit_tx_base_fee(feerate_per_kw, untrimmed) * 1000;
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SUPERVERBOSE("# base commitment transaction fee = %"PRIu64"\n",
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base_fee_msat / 1000);
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@ -200,45 +230,41 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
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&self_pay_msat, &other_pay_msat);
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/* Worst-case sizing: both to-local and to-remote outputs. */
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tx = bitcoin_tx(ctx, 1, tal_count(offered) + tal_count(received) + 2);
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tx = bitcoin_tx(ctx, 1, untrimmed + 2);
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/* We keep track of which outputs have which HTLCs */
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*htlcmap = tal_arr(tx, const struct htlc *, tal_count(tx->output));
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/* This could be done in a single loop, but we follow the BOLT
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* literally to make comments in test vectors clearer. */
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n = 0;
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/* BOLT #3:
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*
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* 3. For every offered HTLC, if it is not trimmed, add an [offered
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* HTLC output](#offered-htlc-outputs).
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* 3. For every offered HTLC, if it is not trimmed, add an
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* [offered HTLC output](#offered-htlc-outputs).
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*/
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n = 0;
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for (i = 0; i < tal_count(offered); i++, n++) {
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u8 *wscript = bitcoin_wscript_htlc_offer(tmpctx,
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selfkey, otherkey,
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&offered[i]->rhash);
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tx->output[n].amount = offered[i]->msatoshi / 1000;
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tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
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(*htlcmap)[n] = offered[i];
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SUPERVERBOSE("# HTLC offered amount %"PRIu64" wscript %s\n",
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tx->output[n].amount,
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tal_hex(tmpctx, wscript));
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for (i = 0; i < tal_count(htlcs); i++) {
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if (htlc_owner(htlcs[i]) != side)
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continue;
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if (trim(htlcs[i], feerate_per_kw, dust_limit_satoshis, side))
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continue;
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add_offered_htlc_out(tx, n, htlcs[i], selfkey, otherkey);
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(*htlcmap)[n++] = htlcs[i];
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}
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/* BOLT #3:
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*
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* 4. For every received HTLC, if it is not trimmed, add an [received
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* HTLC output](#received-htlc-outputs).
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* 4. For every received HTLC, if it is not trimmed, add an
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* [received HTLC output](#received-htlc-outputs).
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*/
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for (i = 0; i < tal_count(received); i++, n++) {
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u8 *wscript = bitcoin_wscript_htlc_receive(tmpctx,
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&received[i]->expiry,
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selfkey, otherkey,
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&received[i]->rhash);
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tx->output[n].amount = received[i]->msatoshi / 1000;
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tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
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(*htlcmap)[n] = received[i];
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SUPERVERBOSE("# HTLC received amount %"PRIu64" wscript %s\n",
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tx->output[n].amount,
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tal_hex(tmpctx, wscript));
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for (i = 0; i < tal_count(htlcs); i++) {
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if (htlc_owner(htlcs[i]) == side)
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continue;
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if (trim(htlcs[i], feerate_per_kw, dust_limit_satoshis, side))
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continue;
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add_received_htlc_out(tx, n, htlcs[i],selfkey, otherkey);
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(*htlcmap)[n++] = htlcs[i];
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}
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/* BOLT #3:
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@ -20,6 +20,23 @@ u64 commit_number_obscurer(const struct pubkey *opener_payment_basepoint,
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u64 htlc_success_fee(u64 feerate_per_kw);
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u64 htlc_timeout_fee(u64 feerate_per_kw);
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/**
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* commit_tx_num_untrimmed: how many of these htlc outputs will commit tx have?
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* @htlcs: tal_arr of HTLCs
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* @feerate_per_kw: feerate to use
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* @dust_limit_satoshis: dust limit below which to trim outputs.
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* @side: from which side's point of view
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*
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* We need @side because HTLC fees are different for offered and
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* received HTLCs.
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*/
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size_t commit_tx_num_untrimmed(const struct htlc **htlcs,
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u64 feerate_per_kw, u64 dust_limit_satoshis,
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enum side side);
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/* Helper to calculate the base fee if we add this extra htlc */
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u64 commit_tx_base_fee(u64 feerate_per_kw, size_t num_untrimmed_htlcs);
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/**
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* commit_tx: create (unsigned) commitment tx to spend the funding tx output
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* @ctx: context to allocate transaction and @htlc_map from.
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@ -10,7 +10,7 @@ update-mocks: $(LIGHTNINGD_TEST_SRC:%=update-mocks/%)
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$(LIGHTNINGD_TEST_PROGRAMS): $(CCAN_OBJS) $(CORE_OBJS) $(CORE_TX_OBJS) $(BITCOIN_OBJS) $(WIRE_OBJS) $(LIBBASE58_OBJS) $(LIGHTNINGD_OLD_LIB_OBJS) utils.o libsecp256k1.a libsodium.a
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$(LIGHTNINGD_TEST_OBJS): $(LIGHTNINGD_HEADERS)
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$(LIGHTNINGD_TEST_OBJS): $(LIGHTNINGD_HEADERS) $(LIGHTNINGD_SRC) $(LIGHTNINGD_LIB_SRC)
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lightningd/tests: $(LIGHTNINGD_TEST_PROGRAMS:%=unittest/%)
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