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permute_tx: reintroduce permute map.

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We used to have a permutation map; this reintroduces a variant which
uses the htlc pointers directly.

We need this because we have to send the htlc-tx signatures in output
order as part of the protocol: without two-stage HTLCs we only needed
to wire them up in the unilateral spend case so we simply brute-forced
the ordering.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2017-02-07 12:14:22 +10:30
parent e11d9304ab
commit 0fe53cc8e7
6 changed files with 37 additions and 8 deletions
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11
lightningd/commit_tx.c
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@@ -154,6 +154,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
u64 local_pay_msat,
u64 remote_pay_msat,
const struct htlc **htlcs,
const struct htlc ***htlcmap,
u64 obscured_commitment_number)
{
const tal_t *tmpctx = tal_tmpctx(ctx);
@@ -199,6 +200,9 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
/* Worst-case sizing: both to-local and to-remote outputs. */
tx = bitcoin_tx(ctx, 1, tal_count(offered) + tal_count(received) + 2);
/* We keep track of which outputs have which HTLCs */
*htlcmap = tal_arr(tx, const struct htlc *, tal_count(tx->output));
/* BOLT #3:
*
* 3. For every offered HTLC, if it is not trimmed, add an [offered
@@ -211,6 +215,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
&offered[i]->rhash);
tx->output[n].amount = offered[i]->msatoshi / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
(*htlcmap)[n] = offered[i];
SUPERVERBOSE("# HTLC offered amount %"PRIu64" wscript %s\n",
tx->output[n].amount,
tal_hex(tmpctx, wscript));
@@ -228,6 +233,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
&received[i]->rhash);
tx->output[n].amount = received[i]->msatoshi / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
(*htlcmap)[n] = received[i];
SUPERVERBOSE("# HTLC received amount %"PRIu64" wscript %s\n",
tx->output[n].amount,
tal_hex(tmpctx, wscript));
@@ -246,6 +252,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
local_delayedkey);
tx->output[n].amount = local_pay_msat / 1000;
tx->output[n].script = scriptpubkey_p2wsh(tx, wscript);
(*htlcmap)[n] = NULL;
SUPERVERBOSE("# to-local amount %"PRIu64" wscript %s\n",
tx->output[n].amount,
tal_hex(tmpctx, wscript));
@@ -268,6 +275,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
*/
tx->output[n].amount = remote_pay_msat / 1000;
tx->output[n].script = scriptpubkey_p2wpkh(tx, remotekey);
(*htlcmap)[n] = NULL;
SUPERVERBOSE("# to-remote amount %"PRIu64" P2WPKH(%s)\n",
tx->output[n].amount,
type_to_string(tmpctx, struct pubkey, remotekey));
@@ -276,13 +284,14 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
assert(n <= tal_count(tx->output));
tal_resize(&tx->output, n);
tal_resize(htlcmap, n);
/* BOLT #3:
*
* 7. Sort the outputs into [BIP 69
* order](#transaction-input-and-output-ordering)
*/
permute_outputs(tx->output, tal_count(tx->output));
permute_outputs(tx->output, tal_count(tx->output), *htlcmap);
/* BOLT #3:
*