channeld: send current features (EXPERIMENTAL_FEATURES)

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

channeld/channeld.c

@@ -2506,6 +2506,25 @@ static void peer_reconnect(struct peer *peer,
 	 *     `commitment_signed` it expects to send.
 	 */
 	send_tlvs->next_to_send = tal_dup(send_tlvs, u64, &peer->next_index[REMOTE]);
+
+	/* BOLT-upgrade_protocol #2:
+	 * - if it initiated the channel:
+	 *   - MUST set `desired_type` to the channel_type it wants for the
+	 *     channel.
+	 */
+	if (peer->channel->opener == LOCAL)
+		send_tlvs->desired_type = channel_type(send_tlvs, peer->channel);
+	else {
+		/* BOLT-upgrade_protocol #2:
+		 * - otherwise:
+		 *  - MUST set `current_type` to the current channel_type of the
+		 *    channel.
+		 *  - MUST set `upgradable` to the channel types it could change
+		 *    to.
+		 *  - MAY not set `upgradable` if it would be empty.
+		 */
+		send_tlvs->current_type = channel_type(send_tlvs, peer->channel);
+	}
 #endif
 
 	/* BOLT #2:

channeld/test/run-full_channel.c

@@ -29,6 +29,9 @@ void memleak_add_helper_(const tal_t *p UNNEEDED, void (*cb)(struct htable *memt
 /* Generated stub for memleak_remove_htable */
 void memleak_remove_htable(struct htable *memtable UNNEEDED, const struct htable *ht UNNEEDED)
 { fprintf(stderr, "memleak_remove_htable called!\n"); abort(); }
+/* Generated stub for set_feature_bit */
+void set_feature_bit(u8 **ptr UNNEEDED, u32 bit UNNEEDED)
+{ fprintf(stderr, "set_feature_bit called!\n"); abort(); }
 /* Generated stub for status_failed */
 void status_failed(enum status_failreason code UNNEEDED,
 		   const char *fmt UNNEEDED, ...)

common/initial_channel.c

@@ -6,12 +6,14 @@
 #include <ccan/array_size/array_size.h>
 #include <ccan/cast/cast.h>
 #include <ccan/tal/str/str.h>
+#include <common/features.h>
 #include <common/fee_states.h>
 #include <common/initial_channel.h>
 #include <common/initial_commit_tx.h>
 #include <common/keyset.h>
 #include <common/type_to_string.h>
 #include <inttypes.h>
+#include <wire/peer_wire.h>
 
 struct channel *new_initial_channel(const tal_t *ctx,
 				    const struct channel_id *cid,
@@ -136,6 +138,56 @@ u32 channel_feerate(const struct channel *channel, enum side side)
 	return get_feerate(channel->fee_states, channel->opener, side);
 }
 
+#if EXPERIMENTAL_FEATURES
+/* BOLT-upgrade_protocol #2:
+ * Channel features are explicitly enumerated as `channel_type` bitfields,
+ * using odd features bits.  The currently defined types are:
+ *   - no features (no bits set)
+ *   - `option_static_remotekey` (bit 13)
+ *   - `option_anchor_outputs` and `option_static_remotekey` (bits 21 and 13)
+ *   - `option_anchors_zero_fee_htlc_tx` and `option_static_remotekey` (bits 23
+ *      and 13)
+ */
+static struct channel_type *new_channel_type(const tal_t *ctx)
+{
+	struct channel_type *type = tal(ctx, struct channel_type);
+
+	type->features = tal_arr(type, u8, 0);
+	return type;
+}
+
+static struct channel_type *type_static_remotekey(const tal_t *ctx)
+{
+	struct channel_type *type = new_channel_type(ctx);
+
+	set_feature_bit(&type->features,
+			OPTIONAL_FEATURE(OPT_STATIC_REMOTEKEY));
+ 	return type;
+}
+
+static struct channel_type *type_anchor_outputs(const tal_t *ctx)
+{
+	struct channel_type *type = new_channel_type(ctx);
+
+	set_feature_bit(&type->features,
+			OPTIONAL_FEATURE(OPT_ANCHOR_OUTPUTS));
+	set_feature_bit(&type->features,
+			OPTIONAL_FEATURE(OPT_STATIC_REMOTEKEY));
+	return type;
+}
+
+struct channel_type *channel_type(const tal_t *ctx,
+				  const struct channel *channel)
+{
+	if (channel->option_anchor_outputs)
+		return type_anchor_outputs(ctx);
+	if (channel->option_static_remotekey)
+		return type_static_remotekey(ctx);
+
+	return new_channel_type(ctx);
+}
+#endif /* EXPERIMENTAL_FEATURES */
+
 static char *fmt_channel_view(const tal_t *ctx, const struct channel_view *view)
 {
 	return tal_fmt(ctx, "{ owed_local=%s,"

common/initial_channel.h

@@ -140,4 +140,13 @@ struct bitcoin_tx *initial_channel_tx(const tal_t *ctx,
  */
 u32 channel_feerate(const struct channel *channel, enum side side);
 
+#if EXPERIMENTAL_FEATURES
+/* BOLT-upgrade_protocol #2:
+ * Channel features are explicitly enumerated as `channel_type` bitfields,
+ * using odd features bits.
+ */
+struct channel_type *channel_type(const tal_t *ctx,
+				  const struct channel *channel);
+#endif /* EXPERIMENTAL_FEATURES */
+
 #endif /* LIGHTNING_COMMON_INITIAL_CHANNEL_H */