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peer: explicitly store the previous revocation hash when sending new update.

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We want to stop keeping old commitment information (except the minimal
txid to commitment-number mapping).  One place we currently use it is
after sending a commitment signature, and before we've received the
revocation for the old commitment.  For this duration, there are two
valid commitment transactions.

So we store "their_prev_revocation_hash" explicitly for this duration.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2016-08-18 14:23:46 +09:30
parent d45161b07b
commit 4319f3ac70
4 changed files with 114 additions and 84 deletions
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26
daemon/packets.c
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@@ -200,8 +200,7 @@ void queue_pkt_revocation(struct peer *peer,
update_revocation__init(u);
u->revocation_preimage
= sha256_to_proto(u, peer->local.commit->prev->revocation_preimage);
u->revocation_preimage = sha256_to_proto(u, preimage);
u->next_revocation_hash
= sha256_to_proto(u, &peer->local.next_revocation_hash);
@@ -468,15 +467,13 @@ Pkt *accept_pkt_commit(struct peer *peer, const Pkt *pkt,
return NULL;
}
Pkt *accept_pkt_revocation(struct peer *peer, const Pkt *pkt,
struct commit_info *ci)
Pkt *accept_pkt_revocation(struct peer *peer, const Pkt *pkt)
{
const UpdateRevocation *r = pkt->update_revocation;
struct sha256 h;
struct sha256 h, preimage;
assert(!ci->revocation_preimage);
ci->revocation_preimage = tal(ci, struct sha256);
proto_to_sha256(r->revocation_preimage, ci->revocation_preimage);
assert(peer->their_prev_revocation_hash);
proto_to_sha256(r->revocation_preimage, &preimage);
/* BOLT #2:
*
@@ -484,16 +481,21 @@ Pkt *accept_pkt_revocation(struct peer *peer, const Pkt *pkt,
* SHA256 hash of `revocation_preimage` matches the previous commitment
* transaction, and MUST fail if it does not.
*/
sha256(&h, ci->revocation_preimage, sizeof(*ci->revocation_preimage));
if (!structeq(&h, &ci->revocation_hash))
sha256(&h, &preimage, sizeof(preimage));
if (!structeq(&h, peer->their_prev_revocation_hash))
return pkt_err(peer, "complete preimage incorrect");
// save revocation preimages in shachain
if (!shachain_add_hash(&peer->their_preimages,
0xFFFFFFFFFFFFFFFFL - ci->commit_num,
ci->revocation_preimage))
0xFFFFFFFFFFFFFFFFL
- (peer->remote.commit->commit_num - 1),
&preimage))
return pkt_err(peer, "preimage not next in shachain");
/* Clear the previous revocation hash. */
peer->their_prev_revocation_hash
= tal_free(peer->their_prev_revocation_hash);
/* Save next revocation hash. */
proto_to_sha256(r->next_revocation_hash,
&peer->remote.next_revocation_hash);