core-lightning/openingd/common.c
Christian Decker 1bd3d8d9f9 openingd: Remove dust check for reserve imposed on us
This check, while in line with the specification, would cause issues
in mixed setups when the funder or fundee allows dust reserves, but
the counterparty does not. It is not an issue for the non-dust reserve
node since in this case it's the peer giving us more flexibility not
the other way around.
2022-09-21 11:25:47 +02:00

247 lines
7.9 KiB
C

#include "config.h"
#include <ccan/ccan/tal/str/str.h>
#include <common/channel_config.h>
#include <common/features.h>
#include <common/initial_commit_tx.h>
#include <common/status.h>
#include <common/type_to_string.h>
#include <hsmd/hsmd_wiregen.h>
#include <openingd/common.h>
#include <wire/wire_sync.h>
/*~ This is the key function that checks that their configuration is reasonable:
* it applied for both the case where they're trying to open a channel, and when
* they've accepted our open. */
bool check_config_bounds(const tal_t *ctx,
struct amount_sat funding,
u32 feerate_per_kw,
u32 max_to_self_delay,
struct amount_msat min_effective_htlc_capacity,
const struct channel_config *remoteconf,
const struct channel_config *localconf,
bool option_anchor_outputs,
char **err_reason)
{
struct amount_sat capacity;
struct amount_sat reserve;
struct amount_sat fee;
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `to_self_delay` is unreasonably large.
*/
if (remoteconf->to_self_delay > max_to_self_delay) {
*err_reason = tal_fmt(ctx,
"to_self_delay %u larger than %u",
remoteconf->to_self_delay,
max_to_self_delay);
return false;
}
/* BOLT #2:
*
* The receiving node MAY fail the channel if:
*...
* - `funding_satoshis` is too small.
* - it considers `htlc_minimum_msat` too large.
* - it considers `max_htlc_value_in_flight_msat` too small.
* - it considers `channel_reserve_satoshis` too large.
* - it considers `max_accepted_htlcs` too small.
*/
/* We accumulate this into an effective bandwidth minimum. */
/* Add both reserves to deduct from capacity. */
if (!amount_sat_add(&reserve,
remoteconf->channel_reserve,
localconf->channel_reserve)) {
*err_reason = tal_fmt(ctx,
"channel_reserve_satoshis %s"
" too large",
type_to_string(ctx, struct amount_sat,
&remoteconf->channel_reserve));
return false;
}
/* BOLT #2:
* - if `option_anchors` applies to this commitment
* transaction and the sending node is the funder:
* - MUST be able to additionally pay for `to_local_anchor` and
* `to_remote_anchor` above its reserve.
*/
/* (We simply include in "reserve" here if they opened). */
if (option_anchor_outputs
&& !amount_sat_add(&reserve, reserve, AMOUNT_SAT(660))) {
*err_reason = tal_fmt(ctx,
"cannot add anchors to reserve %s",
type_to_string(ctx, struct amount_sat,
&reserve));
return false;
}
/* If reserves are larger than total sat, we fail. */
if (!amount_sat_sub(&capacity, funding, reserve)) {
*err_reason = tal_fmt(ctx, "channel_reserve_satoshis %s"
" and %s too large for funding %s",
type_to_string(ctx, struct amount_sat,
&remoteconf->channel_reserve),
type_to_string(ctx, struct amount_sat,
&localconf->channel_reserve),
type_to_string(ctx, struct amount_sat,
&funding));
return false;
}
/* They have to pay for fees, too. Assuming HTLC is dust, though,
* we don't account for an HTLC output. */
fee = commit_tx_base_fee(feerate_per_kw, 0, option_anchor_outputs);
if (!amount_sat_sub(&capacity, capacity, fee)) {
*err_reason = tal_fmt(ctx, "channel_reserve_satoshis %s"
" and %s plus fee %s too large for "
"funding %s",
type_to_string(tmpctx, struct amount_sat,
&remoteconf->channel_reserve),
type_to_string(tmpctx, struct amount_sat,
&localconf->channel_reserve),
type_to_string(tmpctx, struct amount_sat,
&fee),
type_to_string(tmpctx, struct amount_sat,
&funding));
return false;
}
/* If they set the max HTLC value to less than that number, it caps
* the channel capacity. */
if (amount_sat_greater(capacity,
amount_msat_to_sat_round_down(remoteconf->max_htlc_value_in_flight)))
capacity = amount_msat_to_sat_round_down(remoteconf->max_htlc_value_in_flight);
/* If the minimum htlc is greater than the capacity, the channel is
* useless. */
if (amount_msat_greater_sat(remoteconf->htlc_minimum, capacity)) {
*err_reason = tal_fmt(ctx, "htlc_minimum_msat %s"
" too large for funding %s"
" capacity_msat %s",
type_to_string(ctx, struct amount_msat,
&remoteconf->htlc_minimum),
type_to_string(ctx, struct amount_sat,
&funding),
type_to_string(ctx, struct amount_sat,
&capacity));
return false;
}
/* If the resulting channel doesn't meet our minimum "effective capacity"
* set by lightningd, don't bother opening it. */
if (amount_msat_greater_sat(min_effective_htlc_capacity,
capacity)) {
struct amount_sat min_effective_htlc_capacity_sat =
amount_msat_to_sat_round_down(min_effective_htlc_capacity);
*err_reason = tal_fmt(ctx,
"channel capacity with funding %s,"
" reserves %s/%s,"
" max_htlc_value_in_flight_msat is %s,"
" channel capacity is %s, which is below %s",
type_to_string(ctx, struct amount_sat,
&funding),
type_to_string(ctx, struct amount_sat,
&remoteconf->channel_reserve),
type_to_string(ctx, struct amount_sat,
&localconf->channel_reserve),
type_to_string(ctx, struct amount_msat,
&remoteconf->max_htlc_value_in_flight),
type_to_string(ctx, struct amount_sat,
&capacity),
type_to_string(ctx, struct amount_sat,
&min_effective_htlc_capacity_sat));
return false;
}
/* We don't worry about how many HTLCs they accept, as long as > 0! */
if (remoteconf->max_accepted_htlcs == 0) {
*err_reason = tal_fmt(ctx,
"max_accepted_htlcs %u invalid",
remoteconf->max_accepted_htlcs);
return false;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - `max_accepted_htlcs` is greater than 483.
*/
if (remoteconf->max_accepted_htlcs > 483) {
*err_reason = tal_fmt(ctx,
"max_accepted_htlcs %u too large",
remoteconf->max_accepted_htlcs);
return false;
}
return true;
}
u8 *no_upfront_shutdown_script(const tal_t *ctx,
struct feature_set *our_features,
const u8 *their_features)
{
#if DEVELOPER
/* This is a hack, for feature testing */
const char *e = getenv("DEV_OPENINGD_UPFRONT_SHUTDOWN_SCRIPT");
if (e)
return tal_hexdata(ctx, e, strlen(e));
#endif
/* BOLT #2:
*
* - if both nodes advertised the `option_upfront_shutdown_script`
* feature:
* - MUST include `upfront_shutdown_script` with either a valid
* `shutdown_scriptpubkey` as required by `shutdown`
* `scriptpubkey`, or a zero-length `shutdown_scriptpubkey`
* (ie. `0x0000`).
*/
if (feature_negotiated(our_features, their_features,
OPT_UPFRONT_SHUTDOWN_SCRIPT))
return tal_arr(ctx, u8, 0);
return NULL;
}
void validate_initial_commitment_signature(int hsm_fd,
struct bitcoin_tx *tx,
struct bitcoin_signature *sig)
{
struct existing_htlc **htlcs;
struct bitcoin_signature *htlc_sigs;
u32 feerate;
u64 commit_num;
const u8 *msg;
struct secret *old_secret;
struct pubkey next_point;
/* Validate the counterparty's signature. */
htlcs = tal_arr(NULL, struct existing_htlc *, 0);
htlc_sigs = tal_arr(NULL, struct bitcoin_signature, 0);
feerate = 0; /* unused since there are no htlcs */
commit_num = 0;
msg = towire_hsmd_validate_commitment_tx(NULL,
tx,
(const struct simple_htlc **) htlcs,
commit_num,
feerate,
sig,
htlc_sigs);
tal_free(htlc_sigs);
tal_free(htlcs);
wire_sync_write(hsm_fd, take(msg));
msg = wire_sync_read(tmpctx, hsm_fd);
if (!fromwire_hsmd_validate_commitment_tx_reply(tmpctx, msg, &old_secret, &next_point))
status_failed(STATUS_FAIL_HSM_IO,
"Reading validate_commitment_tx reply: %s",
tal_hex(tmpctx, msg));
}