funding: add 64-bit id to HTLCs.

This gives us a reliable way to distinguish HTLCs, even in the face of
duplicate R values.

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

daemon/packets.c

@@ -449,7 +449,7 @@ Pkt *accept_pkt_htlc_add(const tal_t *ctx,
 	if (!funding_b_add_htlc(cur->cstate,
 				cur->stage.add.htlc.msatoshis,
 				&cur->stage.add.htlc.expiry,
-				&cur->stage.add.htlc.rhash)) {
+				&cur->stage.add.htlc.rhash, 0)) {
 		err = pkt_err(ctx, "Cannot afford %"PRIu64" milli-satoshis",
 			      cur->stage.add.htlc.msatoshis);
 		goto fail;

daemon/peer.c

@@ -1473,7 +1473,7 @@ static void do_newhtlc(struct peer *peer, struct newhtlc *newhtlc)
 	 * execute. */
 	cstate = copy_funding(newhtlc, peer->cstate);
 	if (!funding_a_add_htlc(cstate, newhtlc->htlc.msatoshis,
-				&newhtlc->htlc.expiry, &newhtlc->htlc.rhash)) {
+				&newhtlc->htlc.expiry, &newhtlc->htlc.rhash, 0)) {
 		command_fail(newhtlc->jsoncmd,
 			     "Cannot afford %"PRIu64" milli-satoshis",
 			     newhtlc->htlc.msatoshis);

funding.c

@@ -224,7 +224,7 @@ static bool add_htlc(const struct channel_state *cstate,
 		     struct channel_oneside *creator,
 		     struct channel_oneside *recipient,
 		     u32 msatoshis, const struct abs_locktime *expiry,
-		     const struct sha256 *rhash)
+		     const struct sha256 *rhash, uint64_t id)
 {
 	size_t n, nondust;
 
@@ -246,6 +246,7 @@ static bool add_htlc(const struct channel_state *cstate,
 	creator->htlcs[n].msatoshis = msatoshis;
 	creator->htlcs[n].expiry = *expiry;
 	creator->htlcs[n].rhash = *rhash;
+	creator->htlcs[n].id = id;
 	memcheck(&creator->htlcs[n].msatoshis,
 		 sizeof(creator->htlcs[n].msatoshis));
 	memcheck(&creator->htlcs[n].rhash, sizeof(creator->htlcs[n].rhash));
@@ -288,18 +289,18 @@ static void remove_htlc(const struct channel_state *cstate,
 
 bool funding_a_add_htlc(struct channel_state *cstate,
 			u32 msatoshis, const struct abs_locktime *expiry,
-			const struct sha256 *rhash)
+			const struct sha256 *rhash, uint64_t id)
 {
 	return add_htlc(cstate, &cstate->a, &cstate->b,
-			msatoshis, expiry, rhash);
+			msatoshis, expiry, rhash, id);
 }
 
 bool funding_b_add_htlc(struct channel_state *cstate,
 			u32 msatoshis, const struct abs_locktime *expiry,
-			const struct sha256 *rhash)
+			const struct sha256 *rhash, uint64_t id)
 {
 	return add_htlc(cstate, &cstate->b, &cstate->a,
-			msatoshis, expiry, rhash);
+			msatoshis, expiry, rhash, id);
 }
 
 void funding_a_fail_htlc(struct channel_state *cstate, size_t index)
@@ -334,6 +335,17 @@ size_t funding_find_htlc(struct channel_oneside *creator,
 	return i;
 }
 
+size_t funding_htlc_by_id(struct channel_oneside *creator, uint64_t id)
+{
+	size_t i;
+
+	for (i = 0; i < tal_count(creator->htlcs); i++) {
+		if (creator->htlcs[i].id == id)
+			break;
+	}
+	return i;
+}
+
 struct channel_state *copy_funding(const tal_t *ctx,
 				   const struct channel_state *cstate)
 {

funding.h

@@ -7,6 +7,7 @@
 #include <stdbool.h>
 
 struct channel_htlc {
+	u64 id;
 	u64 msatoshis;
 	struct abs_locktime expiry;
 	struct sha256 rhash;
@@ -55,6 +56,7 @@ struct channel_state *copy_funding(const tal_t *ctx,
  * @msatoshis: Millisatoshi A is putting into a HTLC
  * @expiry: time it expires
  * @rhash: hash of redeem secret
+ * @id: 64-bit ID for htlc
  *
  * If A can't afford the HTLC (or still owes its half of the fees),
  * this will return false and leave @cstate unchanged.  Otherwise
@@ -63,11 +65,11 @@ struct channel_state *copy_funding(const tal_t *ctx,
  */
 bool funding_a_add_htlc(struct channel_state *cstate,
 			u32 msatoshis, const struct abs_locktime *expiry,
-			const struct sha256 *rhash);
+			const struct sha256 *rhash, uint64_t id);
 
 bool funding_b_add_htlc(struct channel_state *cstate,
 			u32 msatoshis, const struct abs_locktime *expiry,
-			const struct sha256 *rhash);
+			const struct sha256 *rhash, uint64_t id);
 
 /**
  * funding_a_fail_htlc: remove an HTLC from A's side of cstate, funds to A
@@ -126,6 +128,16 @@ void invert_cstate(struct channel_state *cstate);
 size_t funding_find_htlc(struct channel_oneside *creator,
 			 const struct sha256 *rhash);
 
+/**
+ * funding_htlc_by_id: find an HTLC on this side of the channel by ID.
+ * @creator: channel_state->a or channel_state->b, whichever originated htlc
+ * @id: id for HTLC.
+ *
+ * Returns a number < tal_count(creator->htlcs), or == tal_count(creator->htlcs)
+ * on fail.
+ */
+size_t funding_htlc_by_id(struct channel_oneside *creator, uint64_t id);
+
 /**
  * fee_for_feerate: calculate the fee (in satoshi) for a given fee_rate.
  * @txsize: transaction size in bytes.