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channeld: generate revoke_and_ack before telling lightningd about com…
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…mitment.

The `channel_got_commitsig` we send the lightningd also implies we sent
the revoke_and_ack, as an optimization.  It doesn't currently matter,
since channel_sending_revoke_and_ack doesn't do anything important to the
state, but that changes once we start uploading the entire fee_states.

So now we move our state machine *before* sending to lightningd, in
preparation for sending fee_states too.

Unfortunately, we need to marshall the info to send before we
increment the state, as lightningd expects that.

Signed-off-by: Rusty Russell <[email protected]>
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@rustyrussell @cdecker
rustyrussell authored and cdecker committed Dec 12, 2019
1 parent 8ffd9d5 commit acb89de
Showing 1 changed file with 76 additions and 62 deletions.
138 changes: 76 additions & 62 deletions channeld/channeld.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1259,44 +1259,20 @@ static u8 *make_revocation_msg(const struct peer *peer, u64 revoke_index,
point);
}

static void send_revocation(struct peer *peer)
/* Convert changed htlcs into parts which lightningd expects. */
static void marshall_htlc_info(const tal_t *ctx,
const struct htlc **changed_htlcs,
struct changed_htlc **changed,
struct fulfilled_htlc **fulfilled,
const struct failed_htlc ***failed,
struct added_htlc **added,
struct secret **shared_secret)
{
/* Revoke previous commit, get new point. */
u8 *msg = make_revocation_msg(peer, peer->next_index[LOCAL]-1,
&peer->next_local_per_commit);

/* From now on we apply changes to the next commitment */
peer->next_index[LOCAL]++;

/* If this queues more changes on the other end, send commit. */
if (channel_sending_revoke_and_ack(peer->channel)) {
status_debug("revoke_and_ack made pending: commit timer");
start_commit_timer(peer);
}

sync_crypto_write_no_delay(peer->pps, take(msg));
}

static u8 *got_commitsig_msg(const tal_t *ctx,
u64 local_commit_index,
u32 local_feerate,
const struct bitcoin_signature *commit_sig,
const secp256k1_ecdsa_signature *htlc_sigs,
const struct htlc **changed_htlcs,
const struct bitcoin_tx *committx)
{
struct changed_htlc *changed;
struct fulfilled_htlc *fulfilled;
const struct failed_htlc **failed;
struct added_htlc *added;
struct secret *shared_secret;
u8 *msg;

changed = tal_arr(tmpctx, struct changed_htlc, 0);
added = tal_arr(tmpctx, struct added_htlc, 0);
shared_secret = tal_arr(tmpctx, struct secret, 0);
failed = tal_arr(tmpctx, const struct failed_htlc *, 0);
fulfilled = tal_arr(tmpctx, struct fulfilled_htlc, 0);
*changed = tal_arr(ctx, struct changed_htlc, 0);
*added = tal_arr(ctx, struct added_htlc, 0);
*shared_secret = tal_arr(ctx, struct secret, 0);
*failed = tal_arr(ctx, const struct failed_htlc *, 0);
*fulfilled = tal_arr(ctx, struct fulfilled_htlc, 0);

for (size_t i = 0; i < tal_count(changed_htlcs); i++) {
const struct htlc *htlc = changed_htlcs[i];
Expand All @@ -1317,25 +1293,25 @@ static u8 *got_commitsig_msg(const tal_t *ctx,
memset(&s, 0, sizeof(s));
else
s = *htlc->shared_secret;
tal_arr_expand(&added, a);
tal_arr_expand(&shared_secret, s);
tal_arr_expand(added, a);
tal_arr_expand(shared_secret, s);
} else if (htlc->state == RCVD_REMOVE_COMMIT) {
if (htlc->r) {
struct fulfilled_htlc f;
assert(!htlc->fail && !htlc->failcode);
f.id = htlc->id;
f.payment_preimage = *htlc->r;
tal_arr_expand(&fulfilled, f);
tal_arr_expand(fulfilled, f);
} else {
struct failed_htlc *f;
assert(htlc->fail || htlc->failcode);
f = tal(failed, struct failed_htlc);
f = tal(*failed, struct failed_htlc);
f->id = htlc->id;
f->failcode = htlc->failcode;
f->failreason = cast_const(u8 *, htlc->fail);
f->scid = cast_const(struct short_channel_id *,
htlc->failed_scid);
tal_arr_expand(&failed, f);
tal_arr_expand(failed, f);
}
} else {
struct changed_htlc c;
Expand All @@ -1344,21 +1320,65 @@ static u8 *got_commitsig_msg(const tal_t *ctx,

c.id = htlc->id;
c.newstate = htlc->state;
tal_arr_expand(&changed, c);
tal_arr_expand(changed, c);
}
}
}

msg = towire_channel_got_commitsig(ctx, local_commit_index,
local_feerate,
commit_sig,
htlc_sigs,
added,
shared_secret,
fulfilled,
failed,
changed,
committx);
return msg;
static void send_revocation(struct peer *peer,
const struct bitcoin_signature *commit_sig,
const secp256k1_ecdsa_signature *htlc_sigs,
const struct htlc **changed_htlcs,
const struct bitcoin_tx *committx)
{
struct changed_htlc *changed;
struct fulfilled_htlc *fulfilled;
const struct failed_htlc **failed;
struct added_htlc *added;
struct secret *shared_secret;
const u8 *msg_for_master;

/* Marshall it now before channel_sending_revoke_and_ack changes htlcs */
/* FIXME: Make infrastructure handle state post-revoke_and_ack! */
marshall_htlc_info(tmpctx,
changed_htlcs,
&changed,
&fulfilled,
&failed,
&added,
&shared_secret);

/* Revoke previous commit, get new point. */
u8 *msg = make_revocation_msg(peer, peer->next_index[LOCAL]-1,
&peer->next_local_per_commit);

/* From now on we apply changes to the next commitment */
peer->next_index[LOCAL]++;

/* If this queues more changes on the other end, send commit. */
if (channel_sending_revoke_and_ack(peer->channel)) {
status_debug("revoke_and_ack made pending: commit timer");
start_commit_timer(peer);
}

/* Tell master daemon about commitsig (and by implication, that we're
* sending revoke_and_ack), then wait for it to ack. */
msg_for_master
= towire_channel_got_commitsig(NULL,
peer->next_index[LOCAL] - 1,
channel_feerate(peer->channel, LOCAL),
commit_sig, htlc_sigs,
added,
shared_secret,
fulfilled,
failed,
changed,
committx);
master_wait_sync_reply(tmpctx, peer, take(msg_for_master),
WIRE_CHANNEL_GOT_COMMITSIG_REPLY);

/* Now we can finally send revoke_and_ack to peer */
sync_crypto_write_no_delay(peer->pps, take(msg));
}

static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
Expand Down Expand Up @@ -1488,14 +1508,8 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
status_debug("Received commit_sig with %zu htlc sigs",
tal_count(htlc_sigs));

/* Tell master daemon, then wait for ack. */
msg = got_commitsig_msg(NULL, peer->next_index[LOCAL],
channel_feerate(peer->channel, LOCAL),
&commit_sig, htlc_sigs, changed_htlcs, txs[0]);

master_wait_sync_reply(tmpctx, peer, take(msg),
WIRE_CHANNEL_GOT_COMMITSIG_REPLY);
return send_revocation(peer);
return send_revocation(peer,
&commit_sig, htlc_sigs, changed_htlcs, txs[0]);
}

static u8 *got_revoke_msg(const tal_t *ctx, u64 revoke_num,
Expand Down

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