hsm: new fd type for channeld.

Instead of reusing HSMFD_ECDH, we have an explicit channeld hsm fd,
which can do ECDH and will soon do channel announce signatures as well.

Based-on: Christian Decker <decker.christian@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/hsm/hsm.c

@@ -117,6 +117,27 @@ static struct io_plan *handle_ecdh(struct io_conn *conn, struct daemon_conn *dc)
 	return daemon_conn_read_next(conn, dc);
 }
 
+static struct io_plan *handle_channeld(struct io_conn *conn,
+				       struct daemon_conn *dc)
+{
+	struct client *c = container_of(dc, struct client, dc);
+	enum hsm_client_wire_type t = fromwire_peektype(dc->msg_in);
+
+	switch (t) {
+	case WIRE_HSM_ECDH_REQ:
+		return handle_ecdh(conn, dc);
+
+	case WIRE_HSM_ECDH_RESP:
+		break;
+	}
+
+	daemon_conn_send(c->master,
+			 take(towire_hsmstatus_client_bad_request(c,
+								  c->id,
+								  dc->msg_in)));
+	return io_close(conn);
+}
+
 /* Control messages */
 static void send_init_response(struct daemon_conn *master)
 {
@@ -314,6 +335,25 @@ static void pass_hsmfd_ecdh(struct daemon_conn *master, const u8 *msg)
 	daemon_conn_send_fd(master, fds[1]);
 }
 
+/* Reply to an incoming request for an HSMFD for a channeld. */
+static void pass_hsmfd_channeld(struct daemon_conn *master, const u8 *msg)
+{
+	int fds[2];
+	u64 id;
+
+	if (!fromwire_hsmctl_hsmfd_channeld(msg, NULL, &id))
+		status_failed(WIRE_HSMSTATUS_BAD_REQUEST, "bad HSMFD_CHANNELD");
+
+	if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) != 0)
+		status_failed(WIRE_HSMSTATUS_FD_FAILED,
+			      "creating fds: %s", strerror(errno));
+
+	new_client(master, id, handle_channeld, fds[0]);
+	daemon_conn_send(master,
+			 take(towire_hsmctl_hsmfd_channeld_reply(master)));
+	daemon_conn_send_fd(master, fds[1]);
+}
+
 /* Note that it's the main daemon that asks for the funding signature so it
  * can broadcast it. */
 static void sign_funding_tx(struct daemon_conn *master, const u8 *msg)
@@ -390,12 +430,16 @@ static struct io_plan *control_received_req(struct io_conn *conn,
 	case WIRE_HSMCTL_HSMFD_ECDH:
 		pass_hsmfd_ecdh(master, master->msg_in);
 		return daemon_conn_read_next(conn, master);
+	case WIRE_HSMCTL_HSMFD_CHANNELD:
+		pass_hsmfd_channeld(master, master->msg_in);
+		return daemon_conn_read_next(conn, master);
 	case WIRE_HSMCTL_SIGN_FUNDING:
 		sign_funding_tx(master, master->msg_in);
 		return daemon_conn_read_next(conn, master);
 
 	case WIRE_HSMCTL_INIT_REPLY:
 	case WIRE_HSMCTL_HSMFD_ECDH_FD_REPLY:
+	case WIRE_HSMCTL_HSMFD_CHANNELD_REPLY:
 	case WIRE_HSMCTL_SIGN_FUNDING_REPLY:
 	case WIRE_HSMSTATUS_INIT_FAILED:
 	case WIRE_HSMSTATUS_WRITEMSG_FAILED:

lightningd/hsm/hsm_wire.csv

@@ -44,4 +44,9 @@ hsmctl_sign_funding_reply,104
 hsmctl_sign_funding_reply,0,num_sigs,2
 hsmctl_sign_funding_reply,0,sig,num_sigs*secp256k1_ecdsa_signature
 
+# Request a client socket for a `channeld`, allows signing announcements 
+hsmctl_hsmfd_channeld,5
+hsmctl_hsmfd_channeld,0,unique_id,8
 
+# Empty reply, just an fd
+hsmctl_hsmfd_channeld_reply,105

lightningd/hsm_control.c

@@ -71,10 +71,12 @@ static int hsm_msg(struct subd *hsm, const u8 *msg, const int *fds)
 	/* HSM doesn't send these */
 	case WIRE_HSMCTL_INIT:
 	case WIRE_HSMCTL_HSMFD_ECDH:
+	case WIRE_HSMCTL_HSMFD_CHANNELD:
 	case WIRE_HSMCTL_SIGN_FUNDING:
 
 	/* Replies should be paired to individual requests. */
 	case WIRE_HSMCTL_INIT_REPLY:
+	case WIRE_HSMCTL_HSMFD_CHANNELD_REPLY:
 	case WIRE_HSMCTL_HSMFD_ECDH_FD_REPLY:
 	case WIRE_HSMCTL_SIGN_FUNDING_REPLY:
 		errx(1, "HSM gave invalid message %s", hsm_wire_type_name(t));

lightningd/peer_control.c

@@ -953,8 +953,8 @@ static void peer_start_channeld(struct peer *peer, enum side funder,
 
 	/* Get fd from hsm. */
 	subd_req(peer, peer->ld->hsm,
-		 take(towire_hsmctl_hsmfd_ecdh(peer, peer->unique_id)), -1, 1,
-		 peer_start_channeld_hsmfd, cds);
+		 take(towire_hsmctl_hsmfd_channeld(peer, peer->unique_id)),
+		 -1, 1, peer_start_channeld_hsmfd, cds);
 }
 
 static bool opening_release_tx(struct subd *opening, const u8 *resp,