[alfred] master: alfred: Avoid large send buffer for fixed size IPC commands (5935c1e) - commits - lists.open-mesh.org

12 Jan 2022

Repository : ssh://git@diktynna/alfred
On branch  : master
...

commit 5935c1e910927cf446a251c232fc75af558aff8d
Author: Sven Eckelmann sven@narfation.org
Date:   Tue Jan 4 10:11:02 2022 +0100
alfred: Avoid large send buffer for fixed size IPC commands
For data related IPC commands, a buffer of 65527 bytes is necessary to send
    or receive a complete command. But for non-data related IPC commands
    usually have a fixed size. It is therefore enough to allocate exactly the
    minimum required amount of bytes on the stack for non-data related IPC
    commands.
Signed-off-by: Sven Eckelmann sven@narfation.org
    Acked-by: Marek Lindner mareklindner@neomailbox.ch
...

5935c1e910927cf446a251c232fc75af558aff8d
 client.c | 83 +++++++++++++++++++++++++++++-----------------------------------
 1 file changed, 38 insertions(+), 45 deletions(-)

diff --git a/client.c b/client.c
index e1107bf..b5faf3b 100644
--- a/client.c
+++ b/client.c
@@ -23,7 +23,7 @@
 int alfred_client_request_data(struct globals *globals)
 {
    unsigned char buf[MAX_PAYLOAD], *pos;
-	struct alfred_request_v0 *request;
+	struct alfred_request_v0 request;
    struct alfred_push_data_v0 *push;
    struct alfred_status_v0 *status;
    struct alfred_tlv *tlv;
@@ -34,17 +34,16 @@ int alfred_client_request_data(struct globals *globals)
    if (unix_sock_open_client(globals))
    	return -1;
-	request = (struct alfred_request_v0 *)buf;
-	len = sizeof(*request);
+	len = sizeof(request);
-	request->header.type = ALFRED_REQUEST;
-	request->header.version = ALFRED_VERSION;
-	request->header.length = sizeof(*request) - sizeof(request->header);
-	request->header.length = htons(request->header.length);
-	request->requested_type = globals->clientmode_arg;
-	request->tx_id = get_random_id();
+	request.header.type = ALFRED_REQUEST;
+	request.header.version = ALFRED_VERSION;
+	request.header.length = sizeof(request) - sizeof(request.header);
+	request.header.length = htons(request.header.length);
+	request.requested_type = globals->clientmode_arg;
+	request.tx_id = get_random_id();
-	ret = write(globals->unix_sock, buf, len);
+	ret = write(globals->unix_sock, &request, len);
    if (ret != len)
    	fprintf(stderr, "%s: only wrote %d of %d bytes: %s\n",
    		__func__, ret, len, strerror(errno));
@@ -179,26 +178,24 @@ int alfred_client_set_data(struct globals *globals)
int alfred_client_modeswitch(struct globals *globals)
 {
-	unsigned char buf[MAX_PAYLOAD];
-	struct alfred_modeswitch_v0 *modeswitch;
+	struct alfred_modeswitch_v0 modeswitch;
    int ret, len;
if (unix_sock_open_client(globals))
    	return -1;
-	modeswitch = (struct alfred_modeswitch_v0 *)buf;
-	len = sizeof(*modeswitch);
+	len = sizeof(modeswitch);
-	modeswitch->header.type = ALFRED_MODESWITCH;
-	modeswitch->header.version = ALFRED_VERSION;
-	modeswitch->header.length = htons(len - sizeof(modeswitch->header));
+	modeswitch.header.type = ALFRED_MODESWITCH;
+	modeswitch.header.version = ALFRED_VERSION;
+	modeswitch.header.length = htons(len - sizeof(modeswitch.header));
switch (globals->opmode) {
    case OPMODE_SECONDARY:
-		modeswitch->mode = ALFRED_MODESWITCH_SECONDARY;
+		modeswitch.mode = ALFRED_MODESWITCH_SECONDARY;
    	break;
    case OPMODE_PRIMARY:
-		modeswitch->mode = ALFRED_MODESWITCH_PRIMARY;
+		modeswitch.mode = ALFRED_MODESWITCH_PRIMARY;
    	break;
    default:
    	fprintf(stderr, "%s: unknown opmode %u in modeswitch\n",
@@ -206,7 +203,7 @@ int alfred_client_modeswitch(struct globals *globals)
    	return -1;
    }
-	ret = write(globals->unix_sock, buf, len);
+	ret = write(globals->unix_sock, &modeswitch, len);
    if (ret != len)
    	fprintf(stderr, "%s: only wrote %d of %d bytes: %s\n",
    		__func__, ret, len, strerror(errno));
@@ -248,8 +245,7 @@ static int check_interface(const char *iface)
int alfred_client_change_interface(struct globals *globals)
 {
-	unsigned char buf[MAX_PAYLOAD];
-	struct alfred_change_interface_v0 *change_interface;
+	struct alfred_change_interface_v0 change_interface;
    int ret, len;
    char *input, *token, *saveptr;
    size_t interface_len;
@@ -258,24 +254,23 @@ int alfred_client_change_interface(struct globals *globals)
    	return -1;
interface_len = strlen(globals->change_interface);
-	if (interface_len > sizeof(change_interface->ifaces)) {
+	if (interface_len > sizeof(change_interface.ifaces)) {
    	fprintf(stderr, "%s: interface name list too long, not changing\n",
    		__func__);
    	return 0;
    }
-	change_interface = (struct alfred_change_interface_v0 *)buf;
-	len = sizeof(*change_interface);
+	len = sizeof(change_interface);
-	change_interface->header.type = ALFRED_CHANGE_INTERFACE;
-	change_interface->header.version = ALFRED_VERSION;
-	change_interface->header.length = htons(len - sizeof(change_interface->header));
-	strncpy(change_interface->ifaces, globals->change_interface,
-		sizeof(change_interface->ifaces));
-	change_interface->ifaces[sizeof(change_interface->ifaces) - 1] = '\0';
+	change_interface.header.type = ALFRED_CHANGE_INTERFACE;
+	change_interface.header.version = ALFRED_VERSION;
+	change_interface.header.length = htons(len - sizeof(change_interface.header));
+	strncpy(change_interface.ifaces, globals->change_interface,
+		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->change_interface is now saved in change_interface.ifaces
     * and can be modified by strtok_r
     */
    input = globals->change_interface;
@@ -287,7 +282,7 @@ int alfred_client_change_interface(struct globals *globals)
    		return 0;
    }
-	ret = write(globals->unix_sock, buf, len);
+	ret = write(globals->unix_sock, &change_interface, len);
    if (ret != len)
    	fprintf(stderr, "%s: only wrote %d of %d bytes: %s\n",
    		__func__, ret, len, strerror(errno));
@@ -299,8 +294,7 @@ int alfred_client_change_interface(struct globals *globals)
int alfred_client_change_bat_iface(struct globals *globals)
 {
-	unsigned char buf[MAX_PAYLOAD];
-	struct alfred_change_bat_iface_v0 *change_bat_iface;
+	struct alfred_change_bat_iface_v0 change_bat_iface;
    int ret, len;
    size_t interface_len;
@@ -308,23 +302,22 @@ int alfred_client_change_bat_iface(struct globals *globals)
    	return -1;
interface_len = strlen(globals->mesh_iface);
-	if (interface_len > sizeof(change_bat_iface->bat_iface)) {
+	if (interface_len > sizeof(change_bat_iface.bat_iface)) {
    	fprintf(stderr, "%s: batman-adv interface name list too long, not changing\n",
    		__func__);
    	return 0;
    }
-	change_bat_iface = (struct alfred_change_bat_iface_v0 *)buf;
-	len = sizeof(*change_bat_iface);
+	len = sizeof(change_bat_iface);
-	change_bat_iface->header.type = ALFRED_CHANGE_BAT_IFACE;
-	change_bat_iface->header.version = ALFRED_VERSION;
-	change_bat_iface->header.length = htons(len - sizeof(change_bat_iface->header));
-	strncpy(change_bat_iface->bat_iface, globals->mesh_iface,
-		sizeof(change_bat_iface->bat_iface));
-	change_bat_iface->bat_iface[sizeof(change_bat_iface->bat_iface) - 1] = '\0';
+	change_bat_iface.header.type = ALFRED_CHANGE_BAT_IFACE;
+	change_bat_iface.header.version = ALFRED_VERSION;
+	change_bat_iface.header.length = htons(len - sizeof(change_bat_iface.header));
+	strncpy(change_bat_iface.bat_iface, globals->mesh_iface,
+		sizeof(change_bat_iface.bat_iface));
+	change_bat_iface.bat_iface[sizeof(change_bat_iface.bat_iface) - 1] = '\0';
-	ret = write(globals->unix_sock, buf, len);
+	ret = write(globals->unix_sock, &change_bat_iface, len);
    if (ret != len)
    	fprintf(stderr, "%s: only wrote %d of %d bytes: %s\n",
    		__func__, ret, len, strerror(errno));

    