198 lines
6.5 KiB
C
198 lines
6.5 KiB
C
#include <ccan/ccan/tal/str/str.h>
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#include <common/amount.h>
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#include <common/channel_config.h>
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#include <common/initial_commit_tx.h>
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#include <common/type_to_string.h>
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#include <openingd/common.h>
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/*~ This is the key function that checks that their configuration is reasonable:
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* it applied for both the case where they're trying to open a channel, and when
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* they've accepted our open. */
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bool check_config_bounds(const tal_t *ctx,
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struct amount_sat funding,
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u32 feerate_per_kw,
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u32 max_to_self_delay,
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struct amount_msat min_effective_htlc_capacity,
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const struct channel_config *remoteconf,
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const struct channel_config *localconf,
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bool am_opener,
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bool option_anchor_outputs,
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char **err_reason)
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{
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struct amount_sat capacity;
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struct amount_sat reserve;
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struct amount_sat fee;
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/* BOLT #2:
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*
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* The receiving node MUST fail the channel if:
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*...
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* - `to_self_delay` is unreasonably large.
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*/
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if (remoteconf->to_self_delay > max_to_self_delay) {
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*err_reason = tal_fmt(ctx,
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"to_self_delay %u larger than %u",
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remoteconf->to_self_delay,
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max_to_self_delay);
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return false;
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}
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/* BOLT #2:
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*
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* The receiving node MAY fail the channel if:
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*...
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* - `funding_satoshis` is too small.
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* - it considers `htlc_minimum_msat` too large.
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* - it considers `max_htlc_value_in_flight_msat` too small.
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* - it considers `channel_reserve_satoshis` too large.
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* - it considers `max_accepted_htlcs` too small.
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*/
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/* We accumulate this into an effective bandwidth minimum. */
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/* Add both reserves to deduct from capacity. */
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if (!amount_sat_add(&reserve,
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remoteconf->channel_reserve,
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localconf->channel_reserve)) {
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*err_reason = tal_fmt(ctx,
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"channel_reserve_satoshis %s"
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" too large",
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type_to_string(ctx, struct amount_sat,
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&remoteconf->channel_reserve));
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return false;
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}
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/* BOLT-a12da24dd0102c170365124782b46d9710950ac1 #2:
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* - if `option_anchor_outputs` applies to this commitment
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* transaction and the sending node is the funder:
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* - MUST be able to additionally pay for `to_local_anchor` and
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* `to_remote_anchor` above its reserve.
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*/
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/* (We simply include in "reserve" here if they opened). */
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if (option_anchor_outputs
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&& !am_opener
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&& !amount_sat_add(&reserve, reserve, AMOUNT_SAT(660))) {
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*err_reason = tal_fmt(ctx,
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"cannot add anchors to reserve %s",
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type_to_string(ctx, struct amount_sat,
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&reserve));
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return false;
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}
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/* If reserves are larger than total sat, we fail. */
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if (!amount_sat_sub(&capacity, funding, reserve)) {
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*err_reason = tal_fmt(ctx, "channel_reserve_satoshis %s"
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" and %s too large for funding %s",
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type_to_string(ctx, struct amount_sat,
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&remoteconf->channel_reserve),
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type_to_string(ctx, struct amount_sat,
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&localconf->channel_reserve),
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type_to_string(ctx, struct amount_sat,
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&funding));
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return false;
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}
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/* They have to pay for fees, too. Assuming HTLC is dust, though,
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* we don't account for an HTLC output. */
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fee = commit_tx_base_fee(feerate_per_kw, 0, option_anchor_outputs);
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if (!amount_sat_sub(&capacity, capacity, fee)) {
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*err_reason = tal_fmt(ctx, "channel_reserve_satoshis %s"
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" and %s plus fee %s too large for "
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"funding %s",
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type_to_string(tmpctx, struct amount_sat,
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&remoteconf->channel_reserve),
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type_to_string(tmpctx, struct amount_sat,
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&localconf->channel_reserve),
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type_to_string(tmpctx, struct amount_sat,
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&fee),
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type_to_string(tmpctx, struct amount_sat,
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&funding));
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return false;
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}
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/* If they set the max HTLC value to less than that number, it caps
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* the channel capacity. */
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if (amount_sat_greater(capacity,
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amount_msat_to_sat_round_down(remoteconf->max_htlc_value_in_flight)))
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capacity = amount_msat_to_sat_round_down(remoteconf->max_htlc_value_in_flight);
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/* If the minimum htlc is greater than the capacity, the channel is
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* useless. */
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if (amount_msat_greater_sat(remoteconf->htlc_minimum, capacity)) {
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*err_reason = tal_fmt(ctx, "htlc_minimum_msat %s"
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" too large for funding %s"
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" capacity_msat %s",
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type_to_string(ctx, struct amount_msat,
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&remoteconf->htlc_minimum),
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type_to_string(ctx, struct amount_sat,
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&funding),
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type_to_string(ctx, struct amount_sat,
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&capacity));
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return false;
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}
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/* If the resulting channel doesn't meet our minimum "effective capacity"
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* set by lightningd, don't bother opening it. */
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if (amount_msat_greater_sat(min_effective_htlc_capacity,
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capacity)) {
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*err_reason = tal_fmt(ctx,
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"channel capacity with funding %s,"
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" reserves %s/%s,"
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" max_htlc_value_in_flight_msat is %s,"
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" channel capacity is %s, which is below %s",
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type_to_string(ctx, struct amount_sat,
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&funding),
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type_to_string(ctx, struct amount_sat,
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&remoteconf->channel_reserve),
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type_to_string(ctx, struct amount_sat,
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&localconf->channel_reserve),
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type_to_string(ctx, struct amount_msat,
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&remoteconf->max_htlc_value_in_flight),
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type_to_string(ctx, struct amount_sat,
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&capacity),
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type_to_string(ctx, struct amount_msat,
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&min_effective_htlc_capacity));
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return false;
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}
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/* We don't worry about how many HTLCs they accept, as long as > 0! */
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if (remoteconf->max_accepted_htlcs == 0) {
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*err_reason = tal_fmt(ctx,
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"max_accepted_htlcs %u invalid",
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remoteconf->max_accepted_htlcs);
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return false;
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}
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/* BOLT #2:
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*
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* The receiving node MUST fail the channel if:
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*...
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* - `max_accepted_htlcs` is greater than 483.
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*/
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if (remoteconf->max_accepted_htlcs > 483) {
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*err_reason = tal_fmt(ctx,
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"max_accepted_htlcs %u too large",
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remoteconf->max_accepted_htlcs);
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return false;
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}
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/* BOLT #2:
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*
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* The receiving node MUST fail the channel if:
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*...
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* - `dust_limit_satoshis` is greater than `channel_reserve_satoshis`.
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*/
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if (amount_sat_greater(remoteconf->dust_limit,
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remoteconf->channel_reserve)) {
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*err_reason = tal_fmt(ctx,
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"dust_limit_satoshis %s"
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" too large for channel_reserve_satoshis %s",
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type_to_string(ctx, struct amount_sat,
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&remoteconf->dust_limit),
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type_to_string(ctx, struct amount_sat,
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&remoteconf->channel_reserve));
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return false;
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}
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return true;
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}
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