lightningd: implement receiving warnings.

This takes from the draft spec at lightning/bolts#834

Note that if this draft does not get included, the peer will simply
ignore the warning message (we always close the connection afterwards
anyway).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: Protocol: we now report the new (draft) warning message.

channeld/channeld.c

@@ -1928,6 +1928,7 @@ static void peer_in(struct peer *peer, const u8 *msg)
 	case WIRE_REPLY_SHORT_CHANNEL_IDS_END:
 	case WIRE_PING:
 	case WIRE_PONG:
+	case WIRE_WARNING:
 	case WIRE_ERROR:
 	case WIRE_ONION_MESSAGE:
 		abort();

common/peer_failed.c

@@ -49,7 +49,7 @@ void peer_failed(struct per_peer_state *pps,
 	peer_fatal_continue(take(msg), pps);
 }
 
-/* We're failing because peer sent us an error message */
+/* We're failing because peer sent us an error/warning message */
 void peer_failed_received_errmsg(struct per_peer_state *pps,
 				 const char *desc,
 				 const struct channel_id *channel_id,
@@ -62,7 +62,7 @@ void peer_failed_received_errmsg(struct per_peer_state *pps,
 		channel_id = &all_channels;
 	msg = towire_status_peer_error(NULL, channel_id, desc, soft_error, pps,
 				       NULL);
-	peer_billboard(true, "Received error from peer: %s", desc);
+	peer_billboard(true, "Received %s", desc);
 	peer_fatal_continue(take(msg), pps);
 }
 

common/read_peer_msg.c

@@ -69,11 +69,16 @@ u8 *peer_or_gossip_sync_read(const tal_t *ctx,
 
 bool is_peer_error(const tal_t *ctx, const u8 *msg,
 		   const struct channel_id *channel_id,
-		   char **desc, bool *all_channels)
+		   char **desc, bool *all_channels,
+		   bool *warning)
 {
 	struct channel_id err_chanid;
 
-	if (fromwire_peektype(msg) != WIRE_ERROR)
+	if (fromwire_peektype(msg) == WIRE_ERROR)
+		*warning = false;
+	else if (fromwire_peektype(msg) == WIRE_WARNING)
+		*warning = true;
+	else
 		return false;
 
 	*desc = sanitize_error(ctx, msg, &err_chanid);
@@ -154,7 +159,7 @@ bool handle_peer_gossip_or_error(struct per_peer_state *pps,
 				 const u8 *msg TAKES)
 {
 	char *err;
-	bool all_channels;
+	bool all_channels, warning;
 	struct channel_id actual;
 
 #if DEVELOPER
@@ -181,12 +186,13 @@ bool handle_peer_gossip_or_error(struct per_peer_state *pps,
 		return true;
 	}
 
-	if (is_peer_error(tmpctx, msg, channel_id, &err, &all_channels)) {
+	if (is_peer_error(tmpctx, msg, channel_id, &err, &all_channels,
+			  &warning)) {
 		if (err)
 			peer_failed_received_errmsg(pps, err,
 						    all_channels
 						    ? NULL : channel_id,
-						    soft_error);
+						    warning || soft_error);
 
 		/* Ignore unknown channel errors. */
 		goto handled;

common/read_peer_msg.h

@@ -34,13 +34,14 @@ u8 *peer_or_gossip_sync_read(const tal_t *ctx,
  * @channel_id: the channel id of the current channel.
  * @desc: set to non-NULL if this describes a channel we care about.
  * @all_channels: set to true if this applies to all channels.
+ * @warning: set to true if this is a warning, not an error.
  *
  * If @desc is NULL, ignore this message.  Otherwise, that's usually passed
  * to peer_failed_received_errmsg().
  */
 bool is_peer_error(const tal_t *ctx, const u8 *msg,
 		   const struct channel_id *channel_id,
-		   char **desc, bool *all_channels);
+		   char **desc, bool *all_channels, bool *warning);
 
 /**
  * is_wrong_channel - if it's a message about a different channel, return true

common/wire_error.c

@@ -53,11 +53,16 @@ char *sanitize_error(const tal_t *ctx, const u8 *errmsg,
 	struct channel_id dummy;
 	u8 *data;
 	size_t i;
+	bool warning;
 
 	if (!channel_id)
 		channel_id = &dummy;
 
-	if (!fromwire_error(ctx, errmsg, channel_id, &data))
+	if (fromwire_error(ctx, errmsg, channel_id, &data))
+		warning = false;
+	else if (fromwire_warning(ctx, errmsg, channel_id, &data))
+		warning = true;
+	else
 		return tal_fmt(ctx, "Invalid ERROR message '%s'",
 			       tal_hex(ctx, errmsg));
 
@@ -79,9 +84,10 @@ char *sanitize_error(const tal_t *ctx, const u8 *errmsg,
 		}
 	}
 
-	return tal_fmt(ctx, "channel %s: %.*s",
-		       channel_id_is_all(channel_id)
-		       ? "ALL"
-		       : type_to_string(ctx, struct channel_id, channel_id),
+	return tal_fmt(ctx, "%s%s%s: %.*s",
+		       warning ? "warning" : "error",
+		       channel_id_is_all(channel_id) ? "": " channel ",
+		       channel_id_is_all(channel_id) ? ""
+		       : type_to_string(tmpctx, struct channel_id, channel_id),
 		       (int)tal_count(data), (char *)data);
 }

common/wire_error.h

@@ -43,10 +43,10 @@ u8 *towire_errorfmtv(const tal_t *ctx,
 bool channel_id_is_all(const struct channel_id *channel_id);
 
 /**
- * sanitize_error - extract and sanitize contents of WIRE_ERROR.
+ * sanitize_error - extract and sanitize contents of WIRE_ERROR/WIRE_WARNING.
  *
  * @ctx: context to allocate from
- * @errmsg: the wire_error
+ * @errmsg: the wire_error or wire_warning
  * @channel: (out) channel it's referring to, or NULL if don't care.
  */
 char *sanitize_error(const tal_t *ctx, const u8 *errmsg,

gossipd/gossipd.c

@@ -737,6 +737,7 @@ static struct io_plan *peer_msg_in(struct io_conn *conn,
 		goto handled_relay;
 
 	/* These are non-gossip messages (!is_msg_for_gossipd()) */
+	case WIRE_WARNING:
 	case WIRE_INIT:
 	case WIRE_ERROR:
 	case WIRE_OPEN_CHANNEL:

openingd/dualopend.c

@@ -972,7 +972,7 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state)
 		u8 *msg;
 		bool from_gossipd;
 		char *err;
-		bool all_channels;
+		bool all_channels, warning;
 		struct channel_id actual;
 
 		/* The event loop is responsible for freeing tmpctx, so our
@@ -1011,7 +1011,7 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state)
 
 		/* A helper which decodes an error. */
 		if (is_peer_error(tmpctx, msg, &state->channel_id,
-				  &err, &all_channels)) {
+				  &err, &all_channels, &warning)) {
 			/* BOLT #1:
 			 *
 			 *  - if no existing channel is referred to by the
@@ -1355,6 +1355,7 @@ static bool run_tx_interactive(struct state *state,
 			break;
 		case WIRE_INIT:
 		case WIRE_ERROR:
+		case WIRE_WARNING:
 		case WIRE_OPEN_CHANNEL:
 		case WIRE_ACCEPT_CHANNEL:
 		case WIRE_FUNDING_CREATED:

openingd/openingd.c

@@ -199,7 +199,7 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state,
 		u8 *msg;
 		bool from_gossipd;
 		char *err;
-		bool all_channels;
+		bool all_channels, warning;
 		struct channel_id actual;
 
 		/* The event loop is responsible for freeing tmpctx, so our
@@ -238,7 +238,7 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state,
 
 		/* A helper which decodes an error. */
 		if (is_peer_error(tmpctx, msg, &state->channel_id,
-				  &err, &all_channels)) {
+				  &err, &all_channels, &warning)) {
 			/* BOLT #1:
 			 *
 			 *  - if no existing channel is referred to by the
@@ -262,7 +262,7 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state,
 							    NULL, false);
 			}
 			negotiation_aborted(state, am_opener,
-					    tal_fmt(tmpctx, "They sent error %s",
+					    tal_fmt(tmpctx, "They sent %s",
 						    err));
 			/* Return NULL so caller knows to stop negotiating. */
 			return NULL;

wire/extracted_peer_warning.patch

@@ -0,0 +1,13 @@
+--- wire/peer_exp_wire.csv	2021-01-14 11:00:27.526336550 +1030
++++ -	2021-01-21 15:31:37.071118999 +1030
+@@ -10,6 +10,10 @@
+ msgdata,error,channel_id,channel_id,
+ msgdata,error,len,u16,
+ msgdata,error,data,byte,len
++msgtype,warning,1
++msgdata,warning,channel_id,channel_id,
++msgdata,warning,len,u16,
++msgdata,warning,data,byte,len
+ msgtype,ping,18
+ msgdata,ping,num_pong_bytes,u16,
+ msgdata,ping,byteslen,u16,

wire/peer_wire.c

@@ -4,6 +4,7 @@
 static bool unknown_type(enum peer_wire t)
 {
 	switch (t) {
+	case WIRE_WARNING:
 	case WIRE_INIT:
 	case WIRE_ERROR:
 	case WIRE_OPEN_CHANNEL:
@@ -64,6 +65,7 @@ bool is_msg_for_gossipd(const u8 *cursor)
 	case WIRE_PONG:
 	case WIRE_ONION_MESSAGE:
 		return true;
+	case WIRE_WARNING:
 	case WIRE_INIT:
 	case WIRE_ERROR:
 	case WIRE_OPEN_CHANNEL:

wire/peer_wire.csv

@@ -10,6 +10,10 @@ msgtype,error,17
 msgdata,error,channel_id,channel_id,
 msgdata,error,len,u16,
 msgdata,error,data,byte,len
+msgtype,warning,1
+msgdata,warning,channel_id,channel_id,
+msgdata,warning,len,u16,
+msgdata,warning,data,byte,len
 msgtype,ping,18
 msgdata,ping,num_pong_bytes,u16,
 msgdata,ping,byteslen,u16,