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openingd: ensure that initial channel can cover fees and reserve.

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This is probably covered by our "channel capacity" heuristic which
requires the channel be significant, but best to be explicit and sure.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2018-03-18 15:11:32 +10:30
committed by Christian Decker
parent 441a5b8835
commit 21fbae6df8
6 changed files with 70 additions and 8 deletions
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49
common/initial_commit_tx.c
View File

@@ -4,7 +4,9 @@
#include <common/initial_commit_tx.h>
#include <common/keyset.h>
#include <common/permute_tx.h>
#include <common/status.h>
#include <common/utils.h>
#include <inttypes.h>
/* BOLT #3:
*
@@ -29,7 +31,7 @@ u64 commit_number_obscurer(const struct pubkey *opener_payment_basepoint,
return be64_to_cpu(obscurer);
}
void try_subtract_fee(enum side funder, enum side side,
bool try_subtract_fee(enum side funder, enum side side,
u64 base_fee_msat, u64 *self_msat, u64 *other_msat)
{
u64 *funder_msat;
@@ -39,10 +41,13 @@ void try_subtract_fee(enum side funder, enum side side,
else
funder_msat = other_msat;
if (*funder_msat >= base_fee_msat)
if (*funder_msat >= base_fee_msat) {
*funder_msat -= base_fee_msat;
else
return true;
} else {
*funder_msat = 0;
return false;
}
}
u8 *to_self_wscript(const tal_t *ctx,
@@ -65,6 +70,7 @@ struct bitcoin_tx *initial_commit_tx(const tal_t *ctx,
u64 dust_limit_satoshis,
u64 self_pay_msat,
u64 other_pay_msat,
u64 self_reserve_msat,
u64 obscured_commitment_number,
enum side side)
{
@@ -93,8 +99,41 @@ struct bitcoin_tx *initial_commit_tx(const tal_t *ctx,
* 3. Subtract this base fee from the funder (either `to_local` or
* `to_remote`), with a floor of zero (see [Fee Payment](#fee-payment)).
*/
try_subtract_fee(funder, side, base_fee_msat,
&self_pay_msat, &other_pay_msat);
if (!try_subtract_fee(funder, side, base_fee_msat,
&self_pay_msat, &other_pay_msat)) {
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - the funder's amount for the initial commitment
* transaction is not sufficient for full [fee
* payment](03-transactions.md#fee-payment).
*/
status_unusual("Funder cannot afford fee"
" on initial commitment transaction");
return NULL;
}
/* BOLT #2:
*
* The receiving node MUST fail the channel if:
*...
* - both `to_local` and `to_remote` amounts for the initial
* commitment transaction are less than or equal to
* `channel_reserve_satoshis`.
*/
if (self_pay_msat <= self_reserve_msat
&& other_pay_msat <= self_reserve_msat) {
status_unusual("Neither self amount %"PRIu64
" nor other amount %"PRIu64
" exceed reserve %"PRIu64
" on initial commitment transaction",
self_pay_msat / 1000,
other_pay_msat / 1000,
self_reserve_msat / 1000);
return NULL;
}
/* Worst-case sizing: both to-local and to-remote outputs. */
tx = bitcoin_tx(ctx, 1, untrimmed + 2);