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channeld: implement and refine fee-related functions.

We had some in the header, now implement them, and add a channel_feerate()
accessor.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
ppa-0.6.1
Rusty Russell 7 years ago
committed by Christian Decker
parent
commit
f45d962a14
  1. 6
      channeld/channel.c
  2. 47
      channeld/full_channel.c
  3. 25
      channeld/full_channel.h

6
channeld/channel.c

@ -893,6 +893,12 @@ static struct io_plan *handle_peer_commit_sig(struct io_conn *conn,
"commit_sig with no changes");
}
/* We were supposed to check this was affordable as we go. */
if (peer->channel->funder == REMOTE)
assert(can_funder_afford_feerate(peer->channel,
peer->channel->view[LOCAL]
.feerate_per_kw));
if (!fromwire_commitment_signed(tmpctx, msg, NULL,
&channel_id, &commit_sig, &htlc_sigs))
peer_failed(io_conn_fd(peer->peer_conn),

47
channeld/full_channel.c

@ -678,6 +678,53 @@ static int change_htlcs(struct channel *channel,
return cflags;
}
bool can_funder_afford_feerate(const struct channel *channel, u32 feerate_per_kw)
{
u64 fee_msat, dust = dust_limit_satoshis(channel, !channel->funder);
size_t untrimmed;
const struct htlc **committed, **adding, **removing;
const tal_t *tmpctx = tal_tmpctx(channel);
gather_htlcs(tmpctx, channel, !channel->funder,
&committed, &removing, &adding);
untrimmed = commit_tx_num_untrimmed(committed, feerate_per_kw, dust,
!channel->funder)
+ commit_tx_num_untrimmed(adding, feerate_per_kw, dust,
!channel->funder)
- commit_tx_num_untrimmed(removing, feerate_per_kw, dust,
!channel->funder);
fee_msat = commit_tx_base_fee(feerate_per_kw, untrimmed);
tal_free(tmpctx);
/* BOLT #2:
*
* A receiving node SHOULD fail the channel if the sender cannot afford
* the new fee rate on the receiving node's current commitment
* transaction */
/* Note: sender == funder */
/* How much does it think it has? Must be >= reserve + fee */
return channel->view[!channel->funder].owed_msat[channel->funder]
>= channel_reserve_msat(channel, channel->funder) + fee_msat;
}
bool channel_update_feerate(struct channel *channel, u32 feerate_per_kw)
{
if (!can_funder_afford_feerate(channel, feerate_per_kw))
return false;
channel->view[!channel->funder].feerate_per_kw = feerate_per_kw;
return true;
}
u32 channel_feerate(const struct channel *channel, enum side side)
{
return channel->view[side].feerate_per_kw;
}
/* FIXME: Handle fee changes too. */
bool channel_sending_commit(struct channel *channel,
const struct htlc ***htlcs)

25
channeld/full_channel.h

@ -173,24 +173,33 @@ enum channel_remove_err channel_fulfill_htlc(struct channel *channel,
* approx_max_feerate: what's the we (initiator) could raise fee rate to?
* @channel: The channel state
*
* This is not exact! To check if their offer is valid, use can_afford_feerate.
* This is not exact! To check if their offer is valid, try
* channel_update_feerate.
*/
u32 approx_max_feerate(const struct channel *channel);
/**
* can_afford_feerate: could the initiator pay for the fee at fee_rate?
* can_funder_afford_feerate: could the funder pay the fee?
* @channel: The channel state
* @feerate_per_kw: the new fee rate proposed
* @feerate: The feerate in satoshi per 1000 bytes.
*/
bool can_afford_feerate(const struct channel *channel, u32 feerate_per_kw);
bool can_funder_afford_feerate(const struct channel *channel, u32 feerate);
/**
* adjust_fee: Change fee rate.
* @channel: The channel state
* channel_update_feerate: Change fee rate on non-funder side.
* @channel: The channel
* @feerate_per_kw: fee in satoshi per 1000 bytes.
* @side: which side to adjust.
*
* Returns true if it's affordable, otherwise does nothing.
*/
bool channel_update_feerate(struct channel *channel, u32 feerate_per_kw);
/**
* channel_feerate: Get fee rate for this side of channel.
* @channel: The channel
* @side: the side
*/
void adjust_fee(struct channel *channel, u32 feerate_per_kw, enum side side);
u32 channel_feerate(const struct channel *channel, enum side side);
/**
* channel_sending_commit: commit all remote outstanding changes.

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