diff mbox series

[4/4] alfred: introduce 'server status' IPC call

Message ID 20220102113136.470299-4-mareklindner@neomailbox.ch
State Changes Requested
Delegated to: Simon Wunderlich
Headers show
Series [1/4] alfred: remove meaningless printf() call | expand

Commit Message

Marek Lindner Jan. 2, 2022, 11:31 a.m. UTC
The 'server status' call exports the 'mode' as well as interface
status via IPC. Both parameters can be modified at runtime via the
IPC and as such, the current configuration is dynamic and not
necessarily obvious.

The server status 'request' and 'reply' packet types are added
to allow the IPC client to initiate the status retrieval. The
server will respond with the 'reply' message.

Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
---
 alfred.h     |  2 ++
 client.c     | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 main.c       |  9 +++++-
 man/alfred.8 |  3 ++
 packet.h     | 26 ++++++++++++++++
 unix_sock.c  | 50 ++++++++++++++++++++++++++++++
 6 files changed, 176 insertions(+), 1 deletion(-)

Comments

Sven Eckelmann Jan. 2, 2022, 2:43 p.m. UTC | #1
On Sunday, 2 January 2022 12:31:36 CET Marek Lindner wrote:
> +       list_for_each_entry(interface, &globals->interfaces, list) {
> +               strncpy(status_rep->ifaces[iface_count].name,
> +                       interface->interface,
> +                       sizeof(status_rep->ifaces[iface_count].name));
> +
> +               iface_count++;
> +       }
> +
> +       strncpy(status_rep->bat_iface, globals->mesh_iface,
> +               sizeof(status_rep->bat_iface));

strncpy doesn't guarantee that the copied string ends with a \0. You have to 
take care of that yourself.

This might not be a big problem here because the name buffers in the 
interfaces list have currently the same size as the name buffers in 
status_rep. Still feels better to have the line to manually set \0 at
the end of the buffer.


Another thing I've just noticed: You don't take care of initialization all the 
bytes in the returned buffer. So you might leak data from the alfred process's 
stack to the client.


@Simon, would you prefer to have a global "status" message (which cannot be 
extended in the future) or separate "GET" queries for the existing commands:

* ALFRED_MODESWITCH -> ALFRED_GET_MODE
* ALFRED_CHANGE_INTERFACE -> ALFRED_GET_INTERFACES
* ALFRED_CHANGE_BAT_IFACE -> ALFRED_GET_BAT_IFACE

Kind regards,
	Sven
Sven Eckelmann Jan. 3, 2022, 9:09 a.m. UTC | #2
On Sunday, 2 January 2022 12:31:36 CET Marek Lindner wrote:
> +struct alfred_server_status_rep_v0 {
> +       struct alfred_tlv header;
> +       uint8_t mode;
> +       struct {
> +               char name[IFNAMSIZ];
> +       } ifaces[16];
> +       char bat_iface[IFNAMSIZ];
>  } __packed;

Another thing which came to my mind: maybe it could be interesting to have the 
status of an interface in the reply. So basically if netsock is >= 0 or not. 
Not sure how to deal with the IPv4 mcast code. Most likely just by using 
netsock_mcast and indicator.

Kind regards,
	Sven
Marek Lindner Jan. 12, 2022, 9:14 p.m. UTC | #3
On Sunday, 2 January 2022 15:43:37 CET Sven Eckelmann wrote:
> @Simon, would you prefer to have a global "status" message (which cannot be
> extended in the future) or separate "GET" queries for the existing commands:
> 
> * ALFRED_MODESWITCH -> ALFRED_GET_MODE
> * ALFRED_CHANGE_INTERFACE -> ALFRED_GET_INTERFACES
> * ALFRED_CHANGE_BAT_IFACE -> ALFRED_GET_BAT_IFACE

Another option would be to work with TLVs inside a single server status 
request. This would minimize the number of added packet definitions and retain 
future extensibility.

Cheers,
Marek
Sven Eckelmann Jan. 20, 2022, 8:25 a.m. UTC | #4
On Wednesday, 12 January 2022 22:14:15 CET Marek Lindner wrote:
> On Sunday, 2 January 2022 15:43:37 CET Sven Eckelmann wrote:
> > @Simon, would you prefer to have a global "status" message (which cannot be
> > extended in the future) or separate "GET" queries for the existing commands:
> > 
> > * ALFRED_MODESWITCH -> ALFRED_GET_MODE
> > * ALFRED_CHANGE_INTERFACE -> ALFRED_GET_INTERFACES
> > * ALFRED_CHANGE_BAT_IFACE -> ALFRED_GET_BAT_IFACE
> 
> Another option would be to work with TLVs inside a single server status 
> request. This would minimize the number of added packet definitions and retain 
> future extensibility.

Just asked Simon directly and he seems to prefer the sub-TLV solution over the 
single requests.

Kind regards,
	Sven
diff mbox series

Patch

diff --git a/alfred.h b/alfred.h
index 0fc6dc6..8ee7b21 100644
--- a/alfred.h
+++ b/alfred.h
@@ -90,6 +90,7 @@  enum clientmode {
 	CLIENT_MODESWITCH,
 	CLIENT_CHANGE_INTERFACE,
 	CLIENT_CHANGE_BAT_IFACE,
+	CLIENT_SERVER_STATUS,
 };
 
 struct interface {
@@ -152,6 +153,7 @@  int alfred_client_set_data(struct globals *globals);
 int alfred_client_modeswitch(struct globals *globals);
 int alfred_client_change_interface(struct globals *globals);
 int alfred_client_change_bat_iface(struct globals *globals);
+int alfred_client_server_status(struct globals *globals);
 /* recv.c */
 int recv_alfred_packet(struct globals *globals, struct interface *interface,
 		       int recv_sock);
diff --git a/client.c b/client.c
index e1107bf..d540a9f 100644
--- a/client.c
+++ b/client.c
@@ -333,3 +333,90 @@  int alfred_client_change_bat_iface(struct globals *globals)
 
 	return 0;
 }
+
+int alfred_client_server_status(struct globals *globals)
+{
+	unsigned char buf[MAX_PAYLOAD];
+	struct alfred_server_status_req_v0 *status_req;
+	struct alfred_server_status_rep_v0 *status_rep;
+	struct alfred_tlv *packet;
+	int ret, len, headsize, i;
+
+	if (unix_sock_open_client(globals))
+		return -1;
+
+	status_req = (struct alfred_server_status_req_v0 *)buf;
+	len = sizeof(*status_req);
+
+	status_req->header.type = ALFRED_SERVER_STATUS;
+	status_req->header.version = ALFRED_VERSION;
+	status_req->header.length = 0;
+
+	ret = write(globals->unix_sock, buf, len);
+	if (ret != len)
+		fprintf(stderr, "%s: only wrote %d of %d bytes: %s\n",
+			__func__, ret, len, strerror(errno));
+
+	len = read(globals->unix_sock, buf, sizeof(buf));
+	if (len <= 0) {
+		perror("read from unix socket failed");
+		goto err;
+	}
+
+	ret = -1;
+
+	/* drop too small packets */
+	headsize = sizeof(*packet);
+	if (len < headsize) {
+		perror("unexpected header size received from unix socket");
+		goto err;
+	}
+
+	packet = (struct alfred_tlv *)buf;
+
+	if ((len - headsize) < ((int)ntohs(packet->length))) {
+		perror("unexpected packet size received from unix socket");
+		goto err;
+	}
+
+	if (packet->version != ALFRED_VERSION) {
+		perror("alfred version mismatch");
+		goto err;
+	}
+
+	status_rep = (struct alfred_server_status_rep_v0 *)buf;
+	headsize = ntohs(status_rep->header.length);
+
+	if (headsize < (int)(sizeof(*status_rep) - sizeof(status_rep->header)))
+		goto err;
+
+	fprintf(stdout, "alfred status:\n");
+
+	switch (status_rep->mode) {
+	case ALFRED_MODESWITCH_SECONDARY:
+		fprintf(stdout, "- mode: secondary\n");
+		break;
+	case ALFRED_MODESWITCH_PRIMARY:
+		fprintf(stdout, "- mode: primary\n");
+		break;
+	default:
+		fprintf(stderr, "- mode: unknown\n");
+		break;
+	}
+
+	fprintf(stderr, "- interfaces:\n");
+
+	for (i = 0; i < 16; i++) {
+		if (strlen(status_rep->ifaces[i].name) == 0)
+			continue;
+
+		fprintf(stderr, "\t- name: %s\n",
+			status_rep->ifaces[i].name);
+	}
+
+	fprintf(stdout, "- batman-adv interface: %s\n", status_rep->bat_iface);
+
+err:
+	unix_sock_close(globals);
+	return 0;
+}
diff --git a/main.c b/main.c
index 2cb6d44..e2ac576 100644
--- a/main.c
+++ b/main.c
@@ -38,6 +38,7 @@  static void alfred_usage(void)
 	printf("                   secondary          switch daemon to mode secondary\n");
 	printf("  -I, --change-interface [interface]  change to the specified interface(s)\n");
 	printf("  -B, --change-bat-iface [interface]  change to the specified batman-adv interface\n");
+	printf("  -S, --server-status                 request server status info such as mode & interfaces\n");
 	printf("\n");
 	printf("server mode options:\n");
 	printf("  -i, --interface                     specify the interface (or comma separated list of interfaces) to listen on\n");
@@ -162,6 +163,7 @@  static struct globals *alfred_init(int argc, char *argv[])
 		{"modeswitch",		required_argument,	NULL,	'M'},
 		{"change-interface",	required_argument,	NULL,	'I'},
 		{"change-bat-iface",	required_argument,	NULL,	'B'},
+		{"server-status",	required_argument,	NULL,	'S'},
 		{"unix-path",		required_argument,	NULL,	'u'},
 		{"update-command",	required_argument,	NULL,	'c'},
 		{"version",		no_argument,		NULL,	'v'},
@@ -196,7 +198,7 @@  static struct globals *alfred_init(int argc, char *argv[])
 
 	time_random_seed();
 
-	while ((opt = getopt_long(argc, argv, "ms:r:hi:b:vV:M:I:B:u:dc:p:4:f", long_options,
+	while ((opt = getopt_long(argc, argv, "ms:r:hi:b:vV:M:I:B:Su:dc:p:4:f", long_options,
 				  &opt_ind)) != -1) {
 		switch (opt) {
 		case 'r':
@@ -258,6 +260,9 @@  static struct globals *alfred_init(int argc, char *argv[])
 			globals->clientmode = CLIENT_CHANGE_BAT_IFACE;
 			globals->mesh_iface = strdup(optarg);
 			break;
+		case 'S':
+			globals->clientmode = CLIENT_SERVER_STATUS;
+			break;
 		case 'u':
 			globals->unix_path = optarg;
 			break;
@@ -321,6 +326,8 @@  int main(int argc, char *argv[])
 		return alfred_client_change_interface(globals);
 	case CLIENT_CHANGE_BAT_IFACE:
 		return alfred_client_change_bat_iface(globals);
+	case CLIENT_SERVER_STATUS:
+		return alfred_client_server_status(globals);
 	}
 
 	return 0;
diff --git a/man/alfred.8 b/man/alfred.8
index 74814e0..cf0eafc 100644
--- a/man/alfred.8
+++ b/man/alfred.8
@@ -94,6 +94,9 @@  Change the alfred server to use the new \fBinterface\fP(s)
 .TP
 \fB\-B\fP, \fB\-\-change\-bat\-iface\fP \fIinterface\fP
 Change the alfred server to use the new \fBbatman-adv interface\fP
+.TP
+\fB\-S\fP, \fB\-\-server\-status\fP
+Request server status information such as mode & interfaces\fP
 .
 .SH SERVER OPTIONS
 .TP
diff --git a/packet.h b/packet.h
index 94c6a77..b9e1f2e 100644
--- a/packet.h
+++ b/packet.h
@@ -69,6 +69,7 @@  enum alfred_packet_type {
 	ALFRED_MODESWITCH = 5,
 	ALFRED_CHANGE_INTERFACE = 6,
 	ALFRED_CHANGE_BAT_IFACE = 7,
+	ALFRED_SERVER_STATUS = 8,
 };
 
 /* packets */
@@ -159,6 +160,31 @@  struct alfred_change_interface_v0 {
 struct alfred_change_bat_iface_v0 {
 	struct alfred_tlv header;
 	char bat_iface[IFNAMSIZ];
+};
+
+/**
+ * struct alfred_server_status_req_v0 - server status request
+ * @header: TLV header describing the complete packet
+ *
+ * Sent to the daemon by client
+ */
+struct alfred_server_status_req_v0 {
+	struct alfred_tlv header;
+} __packed;
+
+/**
+ * struct alfred_server_status_req_v0 - server status reply
+ * @header: TLV header describing the complete packet
+ *
+ * Sent by the daemon to client in response to status request
+ */
+struct alfred_server_status_rep_v0 {
+	struct alfred_tlv header;
+	uint8_t mode;
+	struct {
+		char name[IFNAMSIZ];
+	} ifaces[16];
+	char bat_iface[IFNAMSIZ];
 } __packed;
 
 /**
diff --git a/unix_sock.c b/unix_sock.c
index bc39199..22a6805 100644
--- a/unix_sock.c
+++ b/unix_sock.c
@@ -366,6 +366,53 @@  err:
 	return ret;
 }
 
+static int unix_sock_server_status(struct globals *globals, int client_sock)
+{
+	unsigned char buf[MAX_PAYLOAD];
+	struct alfred_server_status_rep_v0 *status_rep;
+	struct interface *interface;
+	int ret, len, iface_count;
+
+	status_rep = (struct alfred_server_status_rep_v0 *)buf;
+	len = sizeof(*status_rep);
+
+	status_rep->header.type = ALFRED_SERVER_STATUS;
+	status_rep->header.version = ALFRED_VERSION;
+	status_rep->header.length = htons(len - sizeof(status_rep->header));
+
+	switch (globals->opmode) {
+	case OPMODE_SECONDARY:
+		status_rep->mode = ALFRED_MODESWITCH_SECONDARY;
+		break;
+	case OPMODE_PRIMARY:
+		status_rep->mode = ALFRED_MODESWITCH_PRIMARY;
+		break;
+	default:
+		break;
+	}
+
+	iface_count = 0;
+
+	list_for_each_entry(interface, &globals->interfaces, list) {
+		strncpy(status_rep->ifaces[iface_count].name,
+			interface->interface,
+			sizeof(status_rep->ifaces[iface_count].name));
+
+		iface_count++;
+	}
+
+	strncpy(status_rep->bat_iface, globals->mesh_iface,
+		sizeof(status_rep->bat_iface));
+
+	ret = write(client_sock, buf, len);
+	if (ret == len)
+		return 0;
+
+	fprintf(stderr, "%s: only wrote %d of %d bytes: %s\n",
+		__func__, ret, len, strerror(errno));
+	return -1;
+}
+
 int unix_sock_read(struct globals *globals)
 {
 	int client_sock;
@@ -428,6 +475,9 @@  int unix_sock_read(struct globals *globals)
 						 (struct alfred_change_bat_iface_v0 *)packet,
 						 client_sock);
 		break;
+	case ALFRED_SERVER_STATUS:
+		ret = unix_sock_server_status(globals, client_sock);
+		break;
 	default:
 		/* unknown packet type */
 		ret = -1;