lightningd: base feerate for onchain txs on deadlines, not fixed fees.
This commit is contained in:
Rusty Russell
parent
3a3370f4c1
commit
819d9882aa
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@ -642,6 +642,29 @@ onchain_witness_htlc_tx(const tal_t *ctx, u8 **witness)
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return cast_const2(const struct onchain_witness_element **, welements);
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}
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/* feerate_for_deadline, but really lowball for distant targets */
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static u32 feerate_for_target(const struct chain_topology *topo, u64 deadline)
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{
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u64 blocks, blockheight;
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blockheight = get_block_height(topo);
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/* Past deadline? Want it now. */
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if (blockheight > deadline)
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return feerate_for_deadline(topo, 1);
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blocks = deadline - blockheight;
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/* Over 200 blocks, we *always* use min fee! */
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if (blocks > 200)
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return FEERATE_FLOOR;
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/* Over 100 blocks, use min fee bitcoind will accept */
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if (blocks > 100)
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return get_feerate_floor(topo);
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return feerate_for_deadline(topo, blocks);
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}
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/* Always sets *welements, returns tx. Sets *worthwhile to false if
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* it wasn't worthwhile at the given feerate (and it had to drop feerate).
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* Returns NULL iff it called channel_internal_error().
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@ -652,7 +675,6 @@ static struct bitcoin_tx *onchaind_tx(const tal_t *ctx,
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struct amount_sat out_sats,
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u32 to_self_delay,
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u32 locktime,
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u32 feerate,
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u8 *(*sign)(const tal_t *ctx,
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const struct bitcoin_tx *tx,
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const struct onchain_signing_info *info),
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@ -661,13 +683,14 @@ static struct bitcoin_tx *onchaind_tx(const tal_t *ctx,
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const struct onchain_witness_element ***welements)
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{
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struct bitcoin_tx *tx;
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struct amount_sat fee, min_out, amt;
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struct amount_sat amt;
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struct bitcoin_signature sig;
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size_t weight;
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u8 *msg;
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u8 **witness;
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struct pubkey final_key;
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struct ext_key final_wallet_ext_key;
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u64 block_target;
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struct lightningd *ld = channel->peer->ld;
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bip32_pubkey(ld, &final_key, channel->final_key_idx);
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@ -692,33 +715,61 @@ static struct bitcoin_tx *onchaind_tx(const tal_t *ctx,
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/* Worst-case sig is 73 bytes */
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weight = bitcoin_tx_weight(tx) + 1 + 3 + 73 + 0 + tal_count(info->wscript);
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weight += elements_tx_overhead(chainparams, 1, 1);
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block_target = info->deadline_block;
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for (;;) {
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struct amount_sat fee;
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u32 feerate;
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feerate = feerate_for_target(ld->topology, block_target);
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fee = amount_tx_fee(feerate, weight);
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/* Result is trivial? Spend with small feerate, but don't wait
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* around for it as it might not confirm. */
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if (!amount_sat_add(&min_out, channel->our_config.dust_limit, fee))
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fatal("Cannot add dust_limit %s and fee %s",
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type_to_string(tmpctx, struct amount_sat, &channel->our_config.dust_limit),
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type_to_string(tmpctx, struct amount_sat, &fee));
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log_debug(channel->log,
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"Feerate for target %"PRIu64" (%+"PRId64" blocks) is %u, fee %s of %s",
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block_target,
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block_target - get_block_height(ld->topology),
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feerate,
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type_to_string(tmpctx, struct amount_sat, &fee),
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type_to_string(tmpctx, struct amount_sat, &out_sats));
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if (amount_sat_less(out_sats, min_out)) {
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/* FIXME: We should use SIGHASH_NONE so others can take it? */
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/* Use lowest possible theoretical fee: who cares if it doesn't propagate */
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fee = amount_tx_fee(FEERATE_FLOOR, weight);
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*worthwhile = false;
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} else
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*worthwhile = true;
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/* If we can afford fee and it's not dust, we're done */
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if (amount_sat_sub(&amt, out_sats, fee)
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&& amount_sat_greater_eq(amt, channel->our_config.dust_limit))
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break;
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/* This can only happen if FEERATE_FLOOR is still too high; shouldn't
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* happen! */
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if (!amount_sat_sub(&amt, out_sats, fee)) {
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/* Hmm, can't afford with recommended fee. Try increasing deadline! */
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block_target++;
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/* If we can't even afford at FEERATE_FLOOR, something is wrong! */
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if (feerate == FEERATE_FLOOR) {
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amt = channel->our_config.dust_limit;
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log_broken(channel->log, "TX can't afford minimal feerate"
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"; setting output to %s",
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type_to_string(tmpctx, struct amount_sat,
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&amt));
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*worthwhile = false;
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type_to_string(tmpctx, struct amount_sat, &amt));
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break;
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}
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}
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/* If we anticipate waiting a long time (say, 20 blocks past
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* the deadline), tell onchaind not to wait */
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*worthwhile = (block_target < info->deadline_block + (u64)20);
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/* If we came close to target, it's worthwhile to wait for. */
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if (block_target != info->deadline_block)
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log_debug(channel->log, "Had to adjust deadline from %u to %"PRIu64" for %s",
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info->deadline_block, block_target,
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type_to_string(tmpctx, struct amount_sat, &out_sats));
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if (!*worthwhile) {
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log_unusual(channel->log,
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"Lowballing feerate for %s sats from %u to %u (deadline %u->%"PRIu64"):"
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" won't count on it being spent!",
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type_to_string(tmpctx, struct amount_sat, &out_sats),
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feerate_for_target(ld->topology, info->deadline_block),
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feerate_for_target(ld->topology, block_target),
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info->deadline_block, block_target);
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}
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bitcoin_tx_output_set_amount(tx, 0, amt);
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bitcoin_tx_finalize(tx);
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@ -798,7 +849,6 @@ static void create_onchain_tx(struct channel *channel,
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struct amount_sat out_sats,
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u32 to_self_delay,
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u32 locktime,
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u32 initial_feerate,
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u8 *(*sign)(const tal_t *ctx,
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const struct bitcoin_tx *tx,
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const struct onchain_signing_info *info),
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@ -808,9 +858,10 @@ static void create_onchain_tx(struct channel *channel,
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struct bitcoin_tx *tx;
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const struct onchain_witness_element **welements;
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bool worthwhile;
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struct lightningd *ld = channel->peer->ld;
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tx = onchaind_tx(tmpctx, channel,
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out, out_sats, to_self_delay, locktime, initial_feerate,
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out, out_sats, to_self_delay, locktime,
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sign, info, &worthwhile, &welements);
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if (!tx)
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return;
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@ -819,7 +870,7 @@ static void create_onchain_tx(struct channel *channel,
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type_to_string(tmpctx, struct bitcoin_tx, tx),
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worthwhile ? "" : "(NOT WORTHWHILE, LOWBALL FEE!)");
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broadcast_tx(channel->peer->ld->topology,
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broadcast_tx(ld->topology,
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channel, take(tx), NULL, false, info->minblock,
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NULL, consider_onchain_rebroadcast, take(info));
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@ -832,11 +883,9 @@ static void create_onchain_tx(struct channel *channel,
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static void handle_onchaind_spend_to_us(struct channel *channel,
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const u8 *msg)
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{
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struct lightningd *ld = channel->peer->ld;
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struct onchain_signing_info *info;
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struct bitcoin_outpoint out;
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struct amount_sat out_sats;
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u32 initial_feerate;
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info = new_signing_info(msg, channel, WIRE_ONCHAIND_SPEND_TO_US);
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@ -870,27 +919,20 @@ static void handle_onchaind_spend_to_us(struct channel *channel,
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return;
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}
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/* FIXME: Be more sophisticated! */
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initial_feerate = delayed_to_us_feerate(ld->topology);
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if (!initial_feerate)
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initial_feerate = tx_feerate(channel->last_tx);
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/* No real deadline on this, it's just returning to our wallet. */
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info->deadline_block = infinite_block_deadline(ld->topology);
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info->deadline_block = infinite_block_deadline(channel->peer->ld->topology);
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create_onchain_tx(channel, &out, out_sats,
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channel->channel_info.their_config.to_self_delay, 0,
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initial_feerate, sign_tx_to_us, info,
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sign_tx_to_us, info,
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__func__);
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}
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static void handle_onchaind_spend_penalty(struct channel *channel,
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const u8 *msg)
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{
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struct lightningd *ld = channel->peer->ld;
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struct onchain_signing_info *info;
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struct bitcoin_outpoint out;
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struct amount_sat out_sats;
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u32 initial_feerate;
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u8 *stack_elem;
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info = new_signing_info(msg, channel, WIRE_ONCHAIND_SPEND_PENALTY);
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@ -908,11 +950,6 @@ static void handle_onchaind_spend_penalty(struct channel *channel,
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/* info->stack_elem is const void * */
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info->stack_elem = stack_elem;
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/* FIXME: Be more sophisticated! */
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initial_feerate = penalty_feerate(ld->topology);
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if (!initial_feerate)
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initial_feerate = tx_feerate(channel->last_tx);
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/* FIXME: deadline for HTLCs is actually a bit longer, but for
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* their output it's channel->our_config.to_self_delay after
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* the commitment tx is mined. */
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@ -920,19 +957,17 @@ static void handle_onchaind_spend_penalty(struct channel *channel,
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+ channel->our_config.to_self_delay;
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create_onchain_tx(channel, &out, out_sats,
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0, 0,
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initial_feerate, sign_penalty, info,
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sign_penalty, info,
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__func__);
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}
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static void handle_onchaind_spend_fulfill(struct channel *channel,
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const u8 *msg)
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{
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struct lightningd *ld = channel->peer->ld;
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struct onchain_signing_info *info;
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struct bitcoin_outpoint out;
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struct amount_sat out_sats;
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struct preimage preimage;
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u32 initial_feerate;
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u64 htlc_id;
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const bool anchor_outputs = channel_has(channel, OPT_ANCHOR_OUTPUTS);
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@ -951,11 +986,6 @@ static void handle_onchaind_spend_fulfill(struct channel *channel,
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}
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info->stack_elem = tal_dup(info, struct preimage, &preimage);
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/* FIXME: Be more sophisticated! */
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initial_feerate = htlc_resolution_feerate(ld->topology);
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if (!initial_feerate)
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initial_feerate = tx_feerate(channel->last_tx);
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info->deadline_block = htlc_incoming_deadline(channel, htlc_id);
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/* BOLT #3:
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*
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@ -965,7 +995,7 @@ static void handle_onchaind_spend_fulfill(struct channel *channel,
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create_onchain_tx(channel, &out, out_sats,
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anchor_outputs ? 1 : 0,
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0,
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initial_feerate, sign_fulfill, info,
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sign_fulfill, info,
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__func__);
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}
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@ -1122,12 +1152,11 @@ static void handle_onchaind_spend_htlc_timeout(struct channel *channel,
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static void handle_onchaind_spend_htlc_expired(struct channel *channel,
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const u8 *msg)
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{
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struct lightningd *ld = channel->peer->ld;
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struct onchain_signing_info *info;
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struct bitcoin_outpoint out;
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struct amount_sat out_sats;
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u64 htlc_id;
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u32 cltv_expiry, initial_feerate;
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u32 cltv_expiry;
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const bool anchor_outputs = channel_has(channel, OPT_ANCHOR_OUTPUTS);
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info = new_signing_info(msg, channel, WIRE_ONCHAIND_SPEND_HTLC_EXPIRED);
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@ -1158,17 +1187,12 @@ static void handle_onchaind_spend_htlc_expired(struct channel *channel,
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/* nLocktime: we have to be *after* that block! */
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info->minblock = cltv_expiry + 1;
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/* FIXME: Be more sophisticated! */
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initial_feerate = htlc_resolution_feerate(ld->topology);
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if (!initial_feerate)
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initial_feerate = tx_feerate(channel->last_tx);
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/* We have to spend it before we can close incoming */
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info->deadline_block = htlc_outgoing_incoming_deadline(channel, htlc_id);
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create_onchain_tx(channel, &out, out_sats,
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anchor_outputs ? 1 : 0,
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cltv_expiry,
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initial_feerate, sign_htlc_expired, info,
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sign_htlc_expired, info,
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__func__);
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}
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