mfc-df: track destination's openchannel version

Plus method to help count/tabulate how many of each we've got
around still.

plugins/spender/multifundchannel.c

@@ -39,6 +39,17 @@ static bool has_all(const struct multifundchannel_command *mfc)
 	return false;
 }
 
+size_t dest_count(const struct multifundchannel_command *mfc,
+		  enum channel_protocol protocol)
+{
+	size_t count = 0, i;
+	for (i = 0; i < tal_count(mfc->destinations); i++) {
+		if (mfc->destinations[i].protocol == protocol)
+			count++;
+	}
+	return count;
+}
+
 /*-----------------------------------------------------------------------------
 Command Cleanup
 -----------------------------------------------------------------------------*/
@@ -380,6 +391,7 @@ param_destinations_array(struct command *cmd, const char *name,
 		dest->error = NULL;
 		dest->psbt = NULL;
 		dest->updated_psbt = NULL;
+		dest->protocol = FUND_CHANNEL;
 
 		/* Only one destination can have "all" indicator.  */
 		if (dest->all) {
@@ -946,6 +958,7 @@ perform_channel_start(struct multifundchannel_command *mfc)
 		if (feature_negotiated(plugin_feature_set(mfc->cmd->plugin),
 				       mfc->destinations[i].their_features,
 				       OPT_DUAL_FUND)) {
+			mfc->destinations[i].protocol = OPEN_CHANNEL;
 			openchannel_init_dest(&mfc->destinations[i]);
 		} else
 #endif /* EXPERIMENTAL_FEATURES */

plugins/spender/multifundchannel.h

@@ -9,6 +9,13 @@
 extern const struct plugin_command multifundchannel_commands[];
 extern const size_t num_multifundchannel_commands;
 
+/* Which protocol this channel open is using.
+ * OPEN_CHANNEL implies opt_dual_fund  */
+enum channel_protocol {
+	FUND_CHANNEL,
+	OPEN_CHANNEL,
+};
+
 /* Current state of the funding process.  */
 enum multifundchannel_state {
 	/* We have not yet performed `fundchannel_start`.  */
@@ -114,9 +121,16 @@ struct multifundchannel_destination {
 	const char *error;
 	errcode_t code;
 
-	/* yarr v2, ahoy! */
+	/* what channel protocol this destination is using */
+	enum channel_protocol protocol;
+
+	/* PSBT for the inflight channel open (OPEN_CHANNEL) */
 	struct wally_psbt *psbt;
+
+	/* PSBT for the inflight channel open, updated (OPEN_CHANNEL) */
 	struct wally_psbt *updated_psbt;
+
+	/* serial of the funding output for this channel (OPEN_CHANNEL) */
 	u64 funding_serial;
 };
 
@@ -221,6 +235,10 @@ mfc_forward_error(struct command *cmd,
 void fail_destination(struct multifundchannel_destination *dest,
 		      char *error TAKES);
 
+/* dest_count - Returns count of destinations using given protocol version */
+size_t dest_count(const struct multifundchannel_command *mfc,
+		  enum channel_protocol);
+
 /* Use this instead of command_finished.  */
 struct command_result *
 mfc_finished(struct multifundchannel_command *, struct json_stream *response);