peer: helpers to extract a given HTLC from commit_info.

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

daemon/peer.c

@@ -20,6 +20,7 @@
 #include <bitcoin/script.h>
 #include <bitcoin/tx.h>
 #include <ccan/array_size/array_size.h>
+#include <ccan/cast/cast.h>
 #include <ccan/io/io.h>
 #include <ccan/list/list.h>
 #include <ccan/noerr/noerr.h>
@@ -743,6 +744,31 @@ static void close_depth_cb(struct peer *peer, unsigned int depth,
 	}
 }
 
+static UNNEEDED struct channel_htlc *htlc_by_index(const struct commit_info *ci, size_t index)
+{
+	if (ci->map[index] == -1)
+		return NULL;
+
+	/* First two are non-HTLC outputs to us, them. */
+	assert(index >= 2);
+	index -= 2;
+
+	if (index < tal_count(ci->cstate->a.htlcs))
+		return cast_const(struct channel_htlc *, ci->cstate->a.htlcs)
+			+ index;
+	index -= tal_count(ci->cstate->a.htlcs);
+	assert(index < tal_count(ci->cstate->b.htlcs));
+	return cast_const(struct channel_htlc *, ci->cstate->b.htlcs) + index;
+}
+
+static UNNEEDED bool htlc_a_offered(struct commit_info *ci, size_t index)
+{
+	assert(index >= 2);
+	index -= 2;
+
+	return index < tal_count(ci->cstate->a.htlcs);
+}
+
 /* We assume the tx is valid!  Don't do a blockchain.info and feed this
  * invalid transactions! */
 static void anchor_spent(struct peer *peer,