netifd: Interface last error support

Adds interface last error support which preserves the last reported
error reported by the protocol handler till the interface is up;
e.g. survives network reload and interface restarts.
This is mainly usefull for tracking down why an interface fails
to establish; eg auth failure/traffic limit for PPP interfaces

Protocol handlers register last error support by setting lasterror=1
in the proto_init function

Signed-off-by: Johan Peeters <johan.peeters111@gmail.com>
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

5 files changed, 37 insertions, 2 deletions

diff --git a/interface.c b/interface.c
index 444f3ac..8239eac 100644
--- a/interface.c
+++ b/interface.c
@@ -80,7 +80,7 @@ const struct uci_blob_param_list interface_attr_list = {
 };
 
 static void
-interface_clear_errors(struct interface *iface)
+interface_error_flush(struct interface *iface)
 {
 	struct interface_error *error, *tmp;
 
@@ -90,6 +90,17 @@ interface_clear_errors(struct interface *iface)
 	}
 }
 
+static void
+interface_clear_errors(struct interface *iface)
+{
+        /* don't flush the errors in case the configured protocol handler matches the
+           running protocol handler and is having the last error capability */
+	if (!(iface->proto &&
+              (iface->proto->handler->flags & PROTO_FLAG_LASTERROR) &&
+              (iface->proto->handler->name == iface->proto_handler->name)))
+		interface_error_flush(iface);
+}
+
 void interface_add_error(struct interface *iface, const char *subsystem,
 			 const char *code, const char **data, int n_data)
 {
@@ -98,6 +109,14 @@ void interface_add_error(struct interface *iface, const char *subsystem,
 	int *datalen = NULL;
 	char *dest, *d_subsys, *d_code;
 
+        /* if the configured protocol handler has the last error support capability,
+           errors should only be added if the running protocol handler matches the
+           configured one */
+	if (iface->proto &&
+            (iface->proto->handler->flags & PROTO_FLAG_LASTERROR) &&
+            (iface->proto->handler->name != iface->proto_handler->name))
+		return;
+
 	if (n_data) {
 		len = n_data * sizeof(char *);
 		datalen = alloca(len);
@@ -113,6 +132,11 @@ void interface_add_error(struct interface *iface, const char *subsystem,
 	if (!error)
 		return;
 
+	/* Only keep the last flagged error, prevent this list grows unlimitted in case the
+	   protocol can't be established (e.g auth failure) */
+	if (iface->proto_handler->flags & PROTO_FLAG_LASTERROR)
+		interface_error_flush(iface);
+
 	list_add_tail(&error->list, &iface->errors);
 
 	dest = (char *) &error->data[n_data + 1];
@@ -188,6 +212,7 @@ interface_event(struct interface *iface, enum interface_event ev)
 
 	switch (ev) {
 	case IFEV_UP:
+		interface_error_flush(iface);
 		adev = iface->l3_dev.dev;
 		/* fall through */
 	case IFEV_DOWN:
diff --git a/proto-shell.c b/proto-shell.c
index 977cdbc..7a1896b 100644
--- a/proto-shell.c
+++ b/proto-shell.c
@@ -819,6 +819,10 @@ proto_shell_add_handler(const char *script, const char *name, json_object *obj)
 	if (tmp && json_object_get_boolean(tmp))
 		handler->proto.flags |= PROTO_FLAG_RENEW_AVAILABLE;
 
+	tmp = json_get_field(obj, "lasterror", json_type_boolean);
+	if (tmp && json_object_get_boolean(tmp))
+		handler->proto.flags |= PROTO_FLAG_LASTERROR;
+
 	config = json_get_field(obj, "config", json_type_array);
 	if (config)
 		handler->config_buf = netifd_handler_parse_config(&handler->config, config);
diff --git a/proto.c b/proto.c
index 0ba2fbe..eaec913 100644
--- a/proto.c
+++ b/proto.c
@@ -586,16 +586,20 @@ void
 proto_attach_interface(struct interface *iface, const char *proto_name)
 {
 	const struct proto_handler *proto = &no_proto;
+	const char *error = NULL;
 
 	if (proto_name) {
 		proto = get_proto_handler(proto_name);
 		if (!proto) {
-			interface_add_error(iface, "proto", "INVALID_PROTO", NULL, 0);
+			error = "INVALID_PROTO";
 			proto = &no_proto;
 		}
 	}
 
 	iface->proto_handler = proto;
+
+	if (error)
+		interface_add_error(iface, "proto", error, NULL, 0);
 }
 
 int
diff --git a/proto.h b/proto.h
index 7210f48..87dec4e 100644
--- a/proto.h
+++ b/proto.h
@@ -37,6 +37,7 @@ enum {
 	PROTO_FLAG_INIT_AVAILABLE = (1 << 2),
 	PROTO_FLAG_RENEW_AVAILABLE = (1 << 3),
 	PROTO_FLAG_FORCE_LINK_DEFAULT = (1 << 4),
+	PROTO_FLAG_LASTERROR = (1 << 5),
 };
 
 struct interface_proto_state {
diff --git a/scripts/netifd-proto.sh b/scripts/netifd-proto.sh
index ce60cd0..95c1bb3 100644
--- a/scripts/netifd-proto.sh
+++ b/scripts/netifd-proto.sh
@@ -375,6 +375,7 @@ init_proto() {
 				json_add_boolean no-device "$no_device"
 				json_add_boolean available "$available"
 				json_add_boolean renew-handler "$renew_handler"
+				json_add_boolean lasterror "$lasterror"
 				json_dump
 			}
 		;;