common: simple helpers to test for either anchor feature.

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

common/channel_type.c

@@ -97,6 +97,12 @@ bool channel_type_has(const struct channel_type *type, int feature)
 	return feature_offered(type->features, feature);
 }
 
+bool channel_type_has_anchors(const struct channel_type *type)
+{
+	return feature_offered(type->features, OPT_ANCHOR_OUTPUTS)
+		|| feature_offered(type->features, OPT_ANCHORS_ZERO_FEE_HTLC_TX);
+}
+
 bool channel_type_eq(const struct channel_type *a,
 		     const struct channel_type *b)
 {

common/channel_type.h

@@ -30,6 +30,9 @@ struct channel_type *default_channel_type(const tal_t *ctx,
 /* Does this type include this feature? */
 bool channel_type_has(const struct channel_type *type, int feature);
 
+/* Convenience for querying either anchor_outputs or anchors_zero_fee_htlc_tx */
+bool channel_type_has_anchors(const struct channel_type *type);
+
 /* Are these two channel_types equivalent? */
 bool channel_type_eq(const struct channel_type *a,
 		     const struct channel_type *b);

common/initial_channel.c

@@ -182,6 +182,11 @@ bool channel_has(const struct channel *channel, int feature)
 	return channel_type_has(channel->type, feature);
 }
 
+bool channel_has_anchors(const struct channel *channel)
+{
+	return channel_type_has_anchors(channel->type);
+}
+
 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

@@ -159,4 +159,8 @@ struct channel_type *channel_desired_type(const tal_t *ctx,
 
 /* Convenience for querying channel->type */
 bool channel_has(const struct channel *channel, int feature);
+
+/* Convenience for querying either anchor_outputs or anchors_zero_fee_htlc_tx */
+bool channel_has_anchors(const struct channel *channel);
+
 #endif /* LIGHTNING_COMMON_INITIAL_CHANNEL_H */