daemon: fulfillhtlc command

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

daemon/jsonrpc.c

@@ -239,6 +239,7 @@ static const struct json_command *cmdlist[] = {
 	&connect_command,
 	&getpeers_command,
 	&newhtlc_command,
+	&fulfillhtlc_command,
 	/* Developer/debugging options. */
 	&echo_command,
 	&rhash_command,

daemon/jsonrpc.h

@@ -59,4 +59,5 @@ void setup_jsonrpc(struct lightningd_state *dstate, const char *rpc_filename);
 extern const struct json_command connect_command;
 extern const struct json_command getpeers_command;
 extern const struct json_command newhtlc_command;
+extern const struct json_command fulfillhtlc_command;
 #endif /* LIGHTNING_DAEMON_JSONRPC_H */

daemon/packets.c

@@ -149,7 +149,14 @@ Pkt *pkt_htlc_update(const tal_t *ctx, const struct peer *peer,
 Pkt *pkt_htlc_fulfill(const tal_t *ctx, const struct peer *peer,
 		      const struct htlc_progress *htlc_prog)
 {
-	FIXME_STUB(peer);
+	UpdateFulfillHtlc *f = tal(ctx, UpdateFulfillHtlc);
+
+	update_fulfill_htlc__init(f);
+
+	f->revocation_hash = sha256_to_proto(f, &htlc_prog->our_revocation_hash);
+	f->r = sha256_to_proto(f, &htlc_prog->r);
+
+	return make_pkt(ctx, PKT__PKT_UPDATE_FULFILL_HTLC, f);
 }
 
 Pkt *pkt_htlc_timedout(const tal_t *ctx, const struct peer *peer,
@@ -437,7 +444,51 @@ Pkt *accept_pkt_htlc_timedout(const tal_t *ctx,
 Pkt *accept_pkt_htlc_fulfill(const tal_t *ctx,
 			     struct peer *peer, const Pkt *pkt)
 {
-	FIXME_STUB(peer);
+	const UpdateFulfillHtlc *f = pkt->update_fulfill_htlc;
+	struct htlc_progress *cur = tal(peer, struct htlc_progress);
+	Pkt *err;
+	size_t i;
+	struct sha256 rhash, r;
+
+	proto_to_sha256(f->r, &r);
+	proto_to_sha256(f->revocation_hash, &cur->their_revocation_hash);
+	sha256(&rhash, &r, sizeof(r));
+	i = funding_find_htlc(&peer->cstate->a, &rhash);
+	if (i == tal_count(peer->cstate->a.htlcs)) {
+		err = pkt_err(ctx, "Unknown HTLC");
+		goto fail;
+	}
+
+	cur->htlc = &peer->cstate->a.htlcs[i];
+
+	/* Removing it should not fail: they gain HTLC amount */
+	cur->cstate = copy_funding(cur, peer->cstate);
+	if (!funding_delta(peer->us.offer_anchor == CMD_OPEN_WITH_ANCHOR,
+			   peer->anchor.satoshis,
+			   -cur->htlc->msatoshis,
+			   -cur->htlc->msatoshis,
+			   &cur->cstate->a, &cur->cstate->b)) {
+		fatal("Unexpected failure fulfilling HTLC of %"PRIu64
+		      " milli-satoshis", cur->htlc->msatoshis);
+	}
+	funding_remove_htlc(&cur->cstate->a, i);
+	
+	peer_get_revocation_hash(peer, peer->num_htlcs+1,
+				 &cur->our_revocation_hash);
+
+	/* Now we create the commit tx pair. */
+	make_commit_txs(cur, peer, &cur->our_revocation_hash,
+			&cur->their_revocation_hash,
+			cur->cstate,
+			&cur->our_commit, &cur->their_commit);
+
+	assert(!peer->current_htlc);
+	peer->current_htlc = cur;
+	return NULL;
+
+fail:
+	tal_free(cur);
+	return err;
 }
 
 static u64 total_funds(const struct channel_oneside *c)

daemon/peer.c

@@ -1070,3 +1070,90 @@ const struct json_command newhtlc_command = {
 	"Offer {id} an HTLC worth {msatoshis} in {expiry} (in seconds since Jan 1 1970) with {rhash}",
 	"Returns an empty result on success"
 };
+
+static void json_fulfillhtlc(struct command *cmd,
+			     const char *buffer, const jsmntok_t *params)
+{
+	struct peer *peer;
+	jsmntok_t *idtok, *rtok;
+	struct pubkey id;
+	struct sha256 rhash;
+	struct htlc_progress *cur;
+	size_t i;
+
+	json_get_params(buffer, params,
+			"id", &idtok,
+			"r", &rtok,
+			NULL);
+
+	if (!idtok || !rtok) {
+		command_fail(cmd, "Need id and r");
+		return;
+	}
+
+	if (!pubkey_from_hexstr(cmd->dstate->secpctx,
+				buffer + idtok->start,
+				idtok->end - idtok->start, &id)) {
+		command_fail(cmd, "Not a valid id");
+		return;
+	}
+	peer = find_peer(cmd->dstate, &id);
+	if (!peer) {
+		command_fail(cmd, "Could not find peer with that id");
+		return;
+	}
+
+	/* Attach to cmd until it's complete. */
+	cur = tal(cmd, struct htlc_progress);
+
+	if (!hex_decode(buffer + rtok->start,
+			rtok->end - rtok->start,
+			&cur->r, sizeof(cur->r))) {
+		command_fail(cmd, "'%.*s' is not a valid sha256 preimage",
+			     (int)(rtok->end - rtok->start),
+			     buffer + rtok->start);
+		return;
+	}
+
+	sha256(&rhash, &cur->r, sizeof(cur->r));
+
+	i = funding_find_htlc(&peer->cstate->b, &rhash);
+	if (i == tal_count(peer->cstate->b.htlcs)) {
+		command_fail(cmd, "'%.*s' preimage htlc not found",
+			     (int)(rtok->end - rtok->start),
+			     buffer + rtok->start);
+		return;
+	}
+	cur->htlc = &peer->cstate->b.htlcs[i];
+
+	/* Removing it should not fail: we gain HTLC amount */
+	cur->cstate = copy_funding(cur, peer->cstate);
+	if (!funding_delta(peer->them.offer_anchor == CMD_OPEN_WITH_ANCHOR,
+			   peer->anchor.satoshis,
+			   -cur->htlc->msatoshis,
+			   -cur->htlc->msatoshis,
+			   &cur->cstate->b, &cur->cstate->a)) {
+		fatal("Unexpected failure fulfilling HTLC of %"PRIu64
+		      " milli-satoshis", cur->htlc->msatoshis);
+		return;
+	}
+	funding_remove_htlc(&cur->cstate->b, i);
+
+	peer_get_revocation_hash(peer, peer->num_htlcs+1,
+				 &cur->our_revocation_hash);
+
+	peer->current_htlc = tal_steal(peer, cur);
+	peer->jsoncmd = cmd;
+
+	/* FIXME: do we need this? */
+	peer->cmddata.htlc_prog = peer->current_htlc;
+	peer->cmd = CMD_SEND_HTLC_FULFILL;
+	try_command(peer);
+}
+	
+const struct json_command fulfillhtlc_command = {
+	"fulfillhtlc",
+	json_fulfillhtlc,
+	"Redeem htlc proposed by {id} using {r}",
+	"Returns an empty result on success"
+};

daemon/peer.h

@@ -30,9 +30,15 @@ struct peer_visible_state {
 };
 
 struct htlc_progress {
+	/* The HTLC we're working on. */
+	struct channel_htlc *htlc;
+
+	/* Set if we're fulfilling. */
+	struct sha256 r;
+	
+	/* Our next state. */
 	/* Channel funding state, after we've completed htlc. */
 	struct channel_state *cstate;
-	struct channel_htlc *htlc;
 	struct sha256 our_revocation_hash, their_revocation_hash;
 	struct bitcoin_tx *our_commit, *their_commit;
 	struct bitcoin_signature their_sig;

daemon/test/test.sh

@@ -93,6 +93,18 @@ $LCLI1 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"them" : { "pay" : 0, "fee"
 $LCLI2 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"them" : { "pay" : 948999000, "fee" : 50000000, "htlcs" : [ { "msatoshis" : 1000000, "expiry" : { "second" : '$EXPIRY' }, "rhash" : "'$RHASH'" } ]'
 $LCLI2 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"us" : { "pay" : 0, "fee" : 0, "htlcs" : [ ]'
 
+$LCLI2 fulfillhtlc $ID1 $SECRET
+
+$LCLI1 getpeers
+# We've transferred the HTLC amount to 2, who now has to pay fees.
+$LCLI1 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"us" : { "pay" : 949999000, "fee" : 49000000, "htlcs" : [ ]'
+$LCLI1 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"them" : { "pay" : 0, "fee" : 1000000, "htlcs" : [ ]'
+
+$LCLI2 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"them" : { "pay" : 949999000, "fee" : 49000000, "htlcs" : [ ]'
+$LCLI2 getpeers | tr -s '\012\011 ' ' ' | fgrep -q '"us" : { "pay" : 0, "fee" : 1000000, "htlcs" : [ ]'
+
+sleep 1
+
 $LCLI1 stop
 $LCLI2 stop
 scripts/shutdown.sh