[PATCH 2/3] alfred: Allow operating without any interface specified

[Marek Lindner <mareklindner@neomailbox.ch>]

The '-i' commandline parameter to specify interface names
no longer is mandatory. Specifying interface 'none' or
sending a 'none' interface string within the
ALFRED_CHANGE_INTERFACE unix socket command disables
all interfaces operations at runtime.

Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
---
 README.rst   |  6 +++++-
 alfred.h     |  2 +-
 client.c     |  8 ++++----
 main.c       |  6 +++---
 man/alfred.8 |  6 +++++-
 netsock.c    |  4 ++++
 server.c     | 39 ++++++++++++++++++++++++---------------
 7 files changed, 46 insertions(+), 25 deletions(-)

diff --git a/README.rst b/README.rst
index 33200e4..7f44db6 100644
--- a/README.rst
+++ b/README.rst
@@ -82,7 +82,8 @@ documentation how to configure alfred in this case. In any event, you can
 still run alfred from the command line. The relevant options are (for a full
 list of options, run alfred -h):
 
-  -i, --interface             specify the interface to listen on
+  -i, --interface             specify the interface to listen on. use 'none'
+                              to disable interface operations
   -b                          specify the batman-adv interface configured on
                               the system (default: bat0). use 'none' to disable
                               the batman-adv based best server selection
@@ -90,6 +91,9 @@ list of options, run alfred -h):
                               accepts data from secondaries and syncs it with
                               other primaries
 
+The interface option '-i' is optional. If interface 'none' is specified, the
+alfred daemon will not communicate with other alfred instances on the
+network unless the interface list is modified at runtime via the unix socket.
 The -b option is optional, and only needed if you run alfred on a batman-adv
 interface not called bat0, or if you don't use batman-adv at all
 (use '-b none'). In this case, alfred will still work but will not be able to
diff --git a/alfred.h b/alfred.h
index c595b06..9ab92a2 100644
--- a/alfred.h
+++ b/alfred.h
@@ -112,7 +112,7 @@ struct interface {
 struct globals {
 	struct list_head interfaces;
 
-	char *change_interface;
+	char *net_iface;
 	struct server *best_server;	/* NULL if we are a server ourselves */
 	char *mesh_iface;
 	enum opmode opmode;
diff --git a/client.c b/client.c
index d0d19fb..b5d8943 100644
--- a/client.c
+++ b/client.c
@@ -252,7 +252,7 @@ int alfred_client_change_interface(struct globals *globals)
 	if (unix_sock_open_client(globals))
 		return -1;
 
-	interface_len = strlen(globals->change_interface);
+	interface_len = strlen(globals->net_iface);
 	if (interface_len > sizeof(change_interface.ifaces)) {
 		fprintf(stderr, "%s: interface name list too long, not changing\n",
 			__func__);
@@ -264,15 +264,15 @@ int alfred_client_change_interface(struct globals *globals)
 	change_interface.header.type = ALFRED_CHANGE_INTERFACE;
 	change_interface.header.version = ALFRED_VERSION;
 	change_interface.header.length = FIXED_TLV_LEN(change_interface);
-	strncpy(change_interface.ifaces, globals->change_interface,
+	strncpy(change_interface.ifaces, globals->net_iface,
 		sizeof(change_interface.ifaces));
 	change_interface.ifaces[sizeof(change_interface.ifaces) - 1] = '\0';
 
 	/* test it before sending
-	 * globals->change_interface is now saved in change_interface.ifaces
+	 * globals->net_iface is now saved in change_interface.ifaces
 	 * and can be modified by strtok_r
 	 */
-	input = globals->change_interface;
+	input = globals->net_iface;
 	while ((token = strtok_r(input, ",", &saveptr))) {
 		input = NULL;
 
diff --git a/main.c b/main.c
index 2cb6d44..d40a0cc 100644
--- a/main.c
+++ b/main.c
@@ -179,7 +179,7 @@ static struct globals *alfred_init(int argc, char *argv[])
 	memset(globals, 0, sizeof(*globals));
 
 	INIT_LIST_HEAD(&globals->interfaces);
-	globals->change_interface = NULL;
+	globals->net_iface = NULL;
 	globals->opmode = OPMODE_SECONDARY;
 	globals->clientmode = CLIENT_NONE;
 	globals->best_server = NULL;
@@ -224,7 +224,7 @@ static struct globals *alfred_init(int argc, char *argv[])
 			globals->opmode = OPMODE_PRIMARY;
 			break;
 		case 'i':
-			netsock_set_interfaces(globals, optarg);
+			globals->net_iface = strdup(optarg);
 			break;
 		case 'b':
 			globals->mesh_iface = strdup(optarg);
@@ -252,7 +252,7 @@ static struct globals *alfred_init(int argc, char *argv[])
 			break;
 		case 'I':
 			globals->clientmode = CLIENT_CHANGE_INTERFACE;
-			globals->change_interface = strdup(optarg);
+			globals->net_iface = strdup(optarg);
 			break;
 		case 'B':
 			globals->clientmode = CLIENT_CHANGE_BAT_IFACE;
diff --git a/man/alfred.8 b/man/alfred.8
index 4e002f0..74814e0 100644
--- a/man/alfred.8
+++ b/man/alfred.8
@@ -98,12 +98,16 @@ Change the alfred server to use the new \fBbatman-adv interface\fP
 .SH SERVER OPTIONS
 .TP
 \fB\-i\fP, \fB\-\-interface\fP \fIiface\fP
-Specify the interface (or comma separated list of interfaces) to listen on
+Specify the interface (or comma separated list of interfaces) to listen on.
+Use 'none' to disable interface operations.
 .TP
 \fB\-b\fP \fIbatmanif\fP
 Specify the batman-adv interface configured on the system (default: bat0).
 Use 'none' to disable the batman-adv based best server selection.
 
+The interface option \fB\-i\fP is optional. If interface 'none' is specified, the
+alfred daemon will not communicate with other alfred instances on the
+network unless the interface list is modified at runtime via the unix socket.
 The \fB\-b\fP option is optional, and only needed if you run alfred on a
 batman-adv interface not called bat0, or if you don't use batman-adv at all
 (use '\fB\-b\fP none'). In this case, alfred will still work but will not be
diff --git a/netsock.c b/netsock.c
index 84b0ec3..128e768 100644
--- a/netsock.c
+++ b/netsock.c
@@ -116,6 +116,10 @@ int netsock_set_interfaces(struct globals *globals, char *interfaces)
 
 	netsock_close_all(globals);
 
+	/* interface 'none' disables all interface operations */
+	if (is_iface_disabled(interfaces))
+		return 0;
+
 	input = interfaces;
 	while ((token = strtok_r(input, ",", &saveptr))) {
 		input = NULL;
diff --git a/server.c b/server.c
index 1efc211..bfc37bc 100644
--- a/server.c
+++ b/server.c
@@ -380,9 +380,30 @@ int alfred_server(struct globals *globals)
 	if (unix_sock_open_daemon(globals))
 		return -1;
 
-	if (list_empty(&globals->interfaces)) {
-		fprintf(stderr, "Can't start server: interface missing\n");
-		return -1;
+	if (!is_iface_disabled(globals->net_iface)) {
+		if (!globals->net_iface) {
+			fprintf(stderr, "Can't start server: interface missing\n");
+			return -1;
+		}
+
+		netsock_set_interfaces(globals, globals->net_iface);
+
+		if (list_empty(&globals->interfaces) && !globals->force) {
+			fprintf(stderr, "Can't start server: valid interface missing\n");
+			return -1;
+		}
+
+		num_socks = netsock_open_all(globals);
+		if (num_socks <= 0 && !globals->force) {
+			fprintf(stderr, "Failed to open interfaces\n");
+			return -1;
+		}
+
+		num_interfaces = netsocket_count_interfaces(globals);
+		if (num_interfaces > 1 && globals->opmode == OPMODE_SECONDARY) {
+			fprintf(stderr, "More than one interface specified in secondary mode\n");
+			return -1;
+		}
 	}
 
 	if (!is_iface_disabled(globals->mesh_iface) &&
@@ -393,18 +414,6 @@ int alfred_server(struct globals *globals)
 		return -1;
 	}
 
-	num_socks = netsock_open_all(globals);
-	if (num_socks <= 0 && !globals->force) {
-		fprintf(stderr, "Failed to open interfaces\n");
-		return -1;
-	}
-
-	num_interfaces = netsocket_count_interfaces(globals);
-	if (num_interfaces > 1 && globals->opmode == OPMODE_SECONDARY) {
-		fprintf(stderr, "More than one interface specified in secondary mode\n");
-		return -1;
-	}
-
 	clock_gettime(CLOCK_MONOTONIC, &last_check);
 	globals->if_check = last_check;
 
-- 
2.32.0.rc0