daemon: code for HTLC maps.

We currently keep copies of HTLCs in each commit_info structure, but
that's redundant.  Keep per-peer per-direction maps of HTLCs, then we can
just throw pointers around (next patch).

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

daemon/Makefile

@@ -52,6 +52,7 @@ DAEMON_HEADERS :=				\
 	daemon/controlled_time.h		\
 	daemon/cryptopkt.h			\
 	daemon/dns.h				\
+	daemon/htlc.h				\
 	daemon/json.h				\
 	daemon/jsonrpc.h			\
 	daemon/lightningd.h			\

daemon/htlc.h

@@ -0,0 +1,49 @@
+#ifndef LIGHTNING_DAEMON_HTLC_H
+#define LIGHTNING_DAEMON_HTLC_H
+#include "config.h"
+#include "bitcoin/locktime.h"
+#include "pseudorand.h"
+#include <ccan/crypto/sha256/sha256.h>
+#include <ccan/crypto/siphash24/siphash24.h>
+#include <ccan/htable/htable_type.h>
+#include <ccan/short_types/short_types.h>
+
+struct htlc {
+	/* Useful for debugging, and decoding via ->src. */
+	struct peer *peer;
+	/* The unique ID for this peer and this direction (ours or theirs) */
+	u64 id;
+	/* The amount in millisatoshi. */
+	u64 msatoshis;
+	/* When the HTLC can no longer be redeemed. */
+	struct abs_locktime expiry;
+	/* The hash of the preimage which can redeem this HTLC */
+	struct sha256 rhash;
+
+	/* FIXME: We could union these together: */
+	/* Routing information sent with this HTLC. */
+	const u8 *routing;
+	/* Previous HTLC (if any) which made us offer this (OURS only) */
+	struct htlc *src;
+};
+
+/* htlc_map: ID -> htlc mapping. */
+static inline u64 htlc_key(const struct htlc *h)
+{
+	return h->id;
+}
+static inline bool htlc_cmp(const struct htlc *h, u64 id)
+{
+	return h->id == id;
+}
+static inline size_t htlc_hash(u64 id)
+{
+	return siphash24(siphash_seed(), &id, sizeof(id));
+}
+HTABLE_DEFINE_TYPE(struct htlc, htlc_key, htlc_hash, htlc_cmp, htlc_map);
+
+static inline size_t htlc_map_count(const struct htlc_map *htlcs)
+{
+	return htlcs->raw.elems;
+}
+#endif /* LIGHTNING_DAEMON_HTLC_H */