hsmd: keep a map of clients.

This means we make sure that we only have one fd per dbid, but more importantly
it enables leak detection, since we can iterate the clients we have.

If we get a second hsmfd request for the same dbid, we free the old
one: sometimes we get the new request before we notice the old daemon
died.  We also have to handle the three 0-value dbid daemons a bit
specially.

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

hsmd/hsm.c

@@ -3,11 +3,13 @@
 #include <bitcoin/pubkey.h>
 #include <bitcoin/script.h>
 #include <bitcoin/tx.h>
+#include <ccan/array_size/array_size.h>
 #include <ccan/cast/cast.h>
 #include <ccan/container_of/container_of.h>
 #include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
 #include <ccan/endian/endian.h>
 #include <ccan/fdpass/fdpass.h>
+#include <ccan/intmap/intmap.h>
 #include <ccan/io/fdpass/fdpass.h>
 #include <ccan/io/io.h>
 #include <ccan/noerr/noerr.h>
@@ -61,6 +63,12 @@ struct client {
 	u64 capabilities;
 };
 
+/* We keep a map of nonzero dbid -> clients */
+static UINTMAP(struct client *) clients;
+/* We get three zero-dbid clients: master, gossipd and connnectd. */
+static struct client *dbid_zero_clients[3];
+static size_t num_dbid_zero_clients;
+
 /* Function declarations for later */
 static struct io_plan *handle_client(struct io_conn *conn,
 				     struct daemon_conn *dc);
@@ -93,6 +101,13 @@ static void node_key(struct privkey *node_privkey, struct pubkey *node_id)
 					     node_privkey->secret.data));
 }
 
+static void destroy_client(struct client *c)
+{
+	if (!uintmap_del(&clients, c->dbid))
+		status_failed(STATUS_FAIL_INTERNAL_ERROR,
+			      "Failed to remove client dbid %"PRIu64, c->dbid);
+}
+
 static struct client *new_client(struct daemon_conn *master,
 				 const struct pubkey *id,
 				 u64 dbid,
@@ -116,6 +131,23 @@ static struct client *new_client(struct daemon_conn *master,
 	tal_steal(master, c->dc.conn);
 	/* Free client when connection freed. */
 	tal_steal(c->dc.conn, c);
+
+	if (dbid == 0) {
+		assert(num_dbid_zero_clients < ARRAY_SIZE(dbid_zero_clients));
+		dbid_zero_clients[num_dbid_zero_clients++] = c;
+	} else {
+		struct client *old_client = uintmap_get(&clients, dbid);
+
+		/* Close conn and free any old client of this dbid. */
+		if (old_client)
+			io_close(old_client->dc.conn);
+
+		if (!uintmap_add(&clients, dbid, c))
+			status_failed(STATUS_FAIL_INTERNAL_ERROR,
+				      "Failed inserting dbid %"PRIu64, dbid);
+		tal_add_destructor(c, destroy_client);
+	}
+
 	return c;
 }
 
@@ -1448,6 +1480,7 @@ int main(int argc, char *argv[])
 	daemon_conn_init(status_conn, status_conn, STDIN_FILENO,
 			 (void *)io_never, NULL);
 	status_setup_async(status_conn);
+	uintmap_init(&clients);
 
 	master = new_client(NULL, NULL, 0, HSM_CAP_MASTER | HSM_CAP_SIGN_GOSSIP,
 			    REQ_FD);