common: add 2 specific error codes wrt funding

Add "peer not connected" and "unknown peer" as error codes, so that
users can check against numeric error codes instead of textual error
messages.

Will ease https://github.com/ElementsProject/lightning/issues/3366

Changelog-None

common/jsonrpc_errors.h

@@ -41,6 +41,8 @@
 #define FUND_OUTPUT_IS_DUST             302
 #define FUNDING_BROADCAST_FAIL          303
 #define FUNDING_STILL_SYNCING_BITCOIN   304
+#define FUNDING_PEER_NOT_CONNECTED      305
+#define FUNDING_UNKNOWN_PEER            306
 
 /* Errors from `invoice` command */
 #define INVOICE_LABEL_ALREADY_EXISTS	900

lightningd/opening_control.c

@@ -1024,7 +1024,7 @@ static struct command_result *json_fund_channel_complete(struct command *cmd,
 	funding_txout = *funding_txout_num;
 	peer = peer_by_id(cmd->ld, id);
 	if (!peer) {
-		return command_fail(cmd, LIGHTNINGD, "Unknown peer");
+		return command_fail(cmd, FUNDING_UNKNOWN_PEER, "Unknown peer");
 	}
 
 	channel = peer_active_channel(peer);
@@ -1033,7 +1033,8 @@ static struct command_result *json_fund_channel_complete(struct command *cmd,
 				    channel_state_name(channel));
 
 	if (!peer->uncommitted_channel)
-		return command_fail(cmd, LIGHTNINGD, "Peer not connected");
+		return command_fail(cmd, FUNDING_PEER_NOT_CONNECTED,
+				    "Peer not connected");
 
 	if (!peer->uncommitted_channel->fc || !peer->uncommitted_channel->fc->inflight)
 		return command_fail(cmd, LIGHTNINGD, "No channel funding in progress.");
@@ -1071,7 +1072,7 @@ static struct command_result *json_fund_channel_cancel(struct command *cmd,
 
 	peer = peer_by_id(cmd->ld, id);
 	if (!peer) {
-		return command_fail(cmd, LIGHTNINGD, "Unknown peer");
+		return command_fail(cmd, FUNDING_UNKNOWN_PEER, "Unknown peer");
 	}
 
 	if (peer->uncommitted_channel) {
@@ -1185,7 +1186,7 @@ static struct command_result *json_fund_channel_start(struct command *cmd,
 
 	peer = peer_by_id(cmd->ld, id);
 	if (!peer) {
-		return command_fail(cmd, LIGHTNINGD, "Unknown peer");
+		return command_fail(cmd, FUNDING_UNKNOWN_PEER, "Unknown peer");
 	}
 
 	channel = peer_active_channel(peer);
@@ -1195,7 +1196,8 @@ static struct command_result *json_fund_channel_start(struct command *cmd,
 	}
 
 	if (!peer->uncommitted_channel) {
-		return command_fail(cmd, LIGHTNINGD, "Peer not connected");
+		return command_fail(cmd, FUNDING_PEER_NOT_CONNECTED,
+				    "Peer not connected");
 	}
 
 	if (peer->uncommitted_channel->fc) {