65 lines
2.0 KiB
C
65 lines
2.0 KiB
C
#include "config.h"
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#include <common/htlc_trim.h>
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#include <common/htlc_tx.h>
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/* If this htlc too small to create an output on @side's commitment tx? */
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bool htlc_is_trimmed(enum side htlc_owner,
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struct amount_msat htlc_amount,
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u32 feerate_per_kw,
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struct amount_sat dust_limit,
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enum side side,
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bool option_anchor_outputs,
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bool option_anchors_zero_fee_htlc_tx)
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{
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struct amount_sat htlc_fee, htlc_min;
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/* BOLT #3:
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*
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* - for every offered HTLC:
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* - if the HTLC amount minus the HTLC-timeout fee would be less than
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* `dust_limit_satoshis` set by the transaction owner:
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* - MUST NOT contain that output.
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* - otherwise:
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* - MUST be generated as specified in
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* [Offered HTLC Outputs](#offered-htlc-outputs).
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*/
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if (htlc_owner == side)
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htlc_fee = htlc_timeout_fee(feerate_per_kw,
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option_anchor_outputs,
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option_anchors_zero_fee_htlc_tx);
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/* BOLT #3:
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*
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* - for every received HTLC:
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* - if the HTLC amount minus the HTLC-success fee would be less than
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* `dust_limit_satoshis` set by the transaction owner:
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* - MUST NOT contain that output.
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* - otherwise:
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* - MUST be generated as specified in
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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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option_anchor_outputs,
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option_anchors_zero_fee_htlc_tx);
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/* If these overflow, it implies htlc must be less. */
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if (!amount_sat_add(&htlc_min, dust_limit, htlc_fee))
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return true;
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return amount_msat_less_sat(htlc_amount, htlc_min);
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}
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/* Minimum amount of headroom we should use for
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* anticipated feerate adjustments */
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#define HTLC_FEE_MIN_RANGE 2530
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#define max(a, b) ((a) > (b) ? (a) : (b))
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u32 htlc_trim_feerate_ceiling(u32 feerate_per_kw)
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{
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/* BOLT-919 #2:
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*
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* `dust_buffer_feerate` is defined as the maximum
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* of either 2530 sats per kWU or 125% of the
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* current `feerate_per_kw`. */
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return max(feerate_per_kw + feerate_per_kw / 4,
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feerate_per_kw + HTLC_FEE_MIN_RANGE);
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}
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