lightningd: forward onion messages.

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

lightningd/Makefile

@@ -75,6 +75,7 @@ LIGHTNINGD_SRC :=				\
 	lightningd/channel_control.c		\
 	lightningd/closing_control.c		\
 	lightningd/connect_control.c		\
+	lightningd/onion_message.c		\
 	lightningd/gossip_control.c		\
 	lightningd/gossip_msg.c			\
 	lightningd/hsm_control.c		\

lightningd/channel_control.c

@@ -21,6 +21,7 @@
 #include <lightningd/jsonrpc.h>
 #include <lightningd/lightningd.h>
 #include <lightningd/log.h>
+#include <lightningd/onion_message.h>
 #include <lightningd/peer_control.h>
 #include <lightningd/subd.h>
 #include <wire/gen_common_wire.h>
@@ -319,11 +320,17 @@ static unsigned channel_msg(struct subd *sd, const u8 *msg, const int *fds)
 	case WIRE_CHANNEL_SEND_ERROR_REPLY:
 		handle_error_channel(sd->channel, msg);
 		break;
+#if EXPERIMENTAL_FEATURES
 	case WIRE_GOT_ONIONMSG_TO_US:
+		handle_onionmsg_to_us(sd->channel, msg);
+		break;
 	case WIRE_GOT_ONIONMSG_FORWARD:
-		/* FIXME */
+		handle_onionmsg_forward(sd->channel, msg);
 		break;
-
+#else
+	case WIRE_GOT_ONIONMSG_TO_US:
+	case WIRE_GOT_ONIONMSG_FORWARD:
+#endif
 	/* And we never get these from channeld. */
 	case WIRE_CHANNEL_INIT:
 	case WIRE_CHANNEL_FUNDING_DEPTH:

lightningd/onion_message.c

@@ -0,0 +1,87 @@
+#include <channeld/gen_channel_wire.h>
+#include <lightningd/channel.h>
+#include <lightningd/lightningd.h>
+#include <lightningd/onion_message.h>
+#include <lightningd/peer_control.h>
+#include <lightningd/subd.h>
+
+#if EXPERIMENTAL_FEATURES
+/* Returns false if we can't tell it */
+static bool make_peer_send(struct lightningd *ld,
+			   struct channel *dst, const u8 *msg TAKES)
+{
+	/* Take ownership of msg (noop if it's taken) */
+	msg = tal_dup_talarr(tmpctx, u8, msg);
+
+	if (!dst) {
+		log_debug(ld->log, "Can't send %s: no channel",
+			  channel_wire_type_name(fromwire_peektype(msg)));
+		return false;
+	}
+
+	if (!dst->owner) {
+		log_debug(ld->log, "Can't send %s: not connected",
+			  channel_wire_type_name(fromwire_peektype(msg)));
+		return false;
+	}
+
+	/* FIXME: We should allow this for closingd too, and we should
+	 * allow incoming via openingd!. */
+	if (!streq(dst->owner->name, "channeld")) {
+		log_debug(ld->log, "Can't send %s: owned by %s",
+			  channel_wire_type_name(fromwire_peektype(msg)),
+			  dst->owner->name);
+		return false;
+	}
+	subd_send_msg(dst->owner, take(msg));
+	return true;
+}
+
+void handle_onionmsg_to_us(struct channel *channel, const u8 *msg)
+{
+	struct pubkey *reply_blinding;
+	struct onionmsg_path **reply_path;
+
+	if (!fromwire_got_onionmsg_to_us(msg, msg,
+					 &reply_blinding, &reply_path)) {
+		channel_internal_error(channel, "bad got_onionmsg_tous: %s",
+				       tal_hex(tmpctx, msg));
+		return;
+	}
+
+	log_info(channel->log, "Got onionmsg%s%s",
+		 reply_blinding ? " reply_blinding": "",
+		 reply_path ? " reply_path": "");
+}
+
+void handle_onionmsg_forward(struct channel *channel, const u8 *msg)
+{
+	struct lightningd *ld = channel->peer->ld;
+	struct short_channel_id *next_scid;
+	struct node_id *next_node;
+	struct pubkey *next_blinding;
+	u8 onion[TOTAL_PACKET_SIZE];
+	struct channel *outchan;
+
+	if (!fromwire_got_onionmsg_forward(msg, msg, &next_scid, &next_node,
+					   &next_blinding, onion)) {
+		channel_internal_error(channel, "bad got_onionmsg_forward: %s",
+				       tal_hex(tmpctx, msg));
+		return;
+	}
+
+	if (next_scid)
+		outchan = active_channel_by_scid(ld, next_scid);
+	else if (next_node) {
+		struct peer *p = peer_by_id(ld, next_node);
+		if (p)
+			outchan = peer_active_channel(p);
+		else
+			outchan = NULL;
+	} else
+		outchan = NULL;
+
+	make_peer_send(ld, outchan,
+		       take(towire_send_onionmsg(NULL, onion, next_blinding)));
+}
+#endif /* EXPERIMENTAL_FEATURES */

lightningd/onion_message.h

@@ -0,0 +1,11 @@
+#ifndef LIGHTNING_LIGHTNINGD_ONION_MESSAGE_H
+#define LIGHTNING_LIGHTNINGD_ONION_MESSAGE_H
+#include "config.h"
+#include <ccan/short_types/short_types.h>
+
+struct channel;
+
+void handle_onionmsg_to_us(struct channel *channel, const u8 *msg);
+void handle_onionmsg_forward(struct channel *channel, const u8 *msg);
+
+#endif /* LIGHTNING_LIGHTNINGD_ONION_MESSAGE_H */