[ALL] Refactoring

[ALL] Send and receive servers
[TODO] Config file reloading is broken

11 files changed, 179 insertions, 126 deletions

diff --git a/src/config.h b/src/config.h
index d5e356e..9400b32 100644
--- a/src/config.h
+++ b/src/config.h
@@ -25,6 +25,7 @@
 #define PORT 5003
 #define SERVER_SOCKET_TIMEOUT 30
 #define HB_INTERVAL 20*HZ
+#define MAX_NUMBER_SERVERS 8
 
 // block device
 #define KERNEL_SECTOR_SIZE 512
diff --git a/src/kernel/blk.c b/src/kernel/blk.c
index 009e3d4..8a76b0d 100644
--- a/src/kernel/blk.c
+++ b/src/kernel/blk.c
@@ -91,8 +91,8 @@ struct block_device_operations dnbd3_blk_ops =
 
 int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
 {
-    dnbd3_device_t *lo = bdev->bd_disk->private_data;
-    int minor = lo->disk->first_minor;
+    dnbd3_device_t *dev = bdev->bd_disk->private_data;
+    int minor = dev->disk->first_minor;
 
     dnbd3_ioctl_t *msg = kmalloc(sizeof(dnbd3_ioctl_t), GFP_KERNEL);
     copy_from_user((char *)msg, (char *)arg, sizeof(*msg));
@@ -100,23 +100,23 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
     switch (cmd)
     {
     case IOCTL_OPEN:
-        strcpy(lo->host, msg->host);
-        strcpy(lo->port, msg->port);
-        lo->vid = msg->vid;
-        lo->rid = msg->rid;
-        dnbd3_net_connect(lo);
+        strcpy(dev->host, msg->host);
+        strcpy(dev->port, msg->port);
+        dev->vid = msg->vid;
+        dev->rid = msg->rid;
+        dnbd3_net_connect(dev);
         break;
 
     case IOCTL_CLOSE:
-        dnbd3_net_disconnect(lo);
-        dnbd3_blk_del_device(lo);
-        dnbd3_blk_add_device(lo, minor);
+        dnbd3_net_disconnect(dev);
+        dnbd3_blk_del_device(dev);
+        dnbd3_blk_add_device(dev, minor);
         break;
 
     case IOCTL_SWITCH:
-        dnbd3_net_disconnect(lo);
-        strcpy(lo->host, msg->host);
-        dnbd3_net_connect(lo);
+        dnbd3_net_disconnect(dev);
+        strcpy(dev->host, msg->host);
+        dnbd3_net_connect(dev);
         break;
 
     case BLKFLSBUF:
@@ -133,11 +133,11 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 void dnbd3_blk_request(struct request_queue *q)
 {
     struct request *req;
-    dnbd3_device_t *lo;
+    dnbd3_device_t *dev;
 
     while ((req = blk_fetch_request(q)) != NULL)
     {
-        lo = req->rq_disk->private_data;
+        dev = req->rq_disk->private_data;
 
         if (req->cmd_type != REQ_TYPE_FS)
         {
@@ -147,9 +147,9 @@ void dnbd3_blk_request(struct request_queue *q)
 
         if (rq_data_dir(req) == READ)
         {
-            list_add_tail(&req->queuelist, &lo->request_queue_send);
+            list_add_tail(&req->queuelist, &dev->request_queue_send);
             spin_unlock_irq(q->queue_lock);
-            wake_up(&lo->process_queue_send);
+            wake_up(&dev->process_queue_send);
             spin_lock_irq(q->queue_lock);
         }
     }
diff --git a/src/kernel/dnbd3.h b/src/kernel/dnbd3.h
index 8dc0f47..c260e18 100644
--- a/src/kernel/dnbd3.h
+++ b/src/kernel/dnbd3.h
@@ -46,6 +46,10 @@ typedef struct
     struct timer_list hb_timer;
     struct request hb_request;
 
+    int num_servers;
+    struct in_addr servers[MAX_NUMBER_SERVERS];
+
+
     // process
     struct task_struct *thread_send;
     struct task_struct *thread_receive;
diff --git a/src/kernel/net.c b/src/kernel/net.c
index a90dfb8..11edd0c 100644
--- a/src/kernel/net.c
+++ b/src/kernel/net.c
@@ -21,50 +21,51 @@
 #include "net.h"
 #include "utils.h"
 
-void dnbd3_net_connect(dnbd3_device_t *lo)
+void dnbd3_net_connect(dnbd3_device_t *dev)
 {
     struct sockaddr_in sin;
     struct msghdr msg;
     struct kvec iov;
     dnbd3_request_t dnbd3_request;
     dnbd3_reply_t dnbd3_reply;
+    uint64_t filesize;
 
-    if (!lo->host || !lo->port || (lo->vid == 0))
+    if (!dev->host || !dev->port || (dev->vid == 0))
     {
         printk("ERROR: Host, port or vid not set.\n");
         return;
     }
 
-    if (lo->sock)
+    if (dev->sock)
     {
-        printk("ERROR: Device %s already connected to %s.\n", lo->disk->disk_name, lo->host);
+        printk("ERROR: Device %s already connected to %s.\n", dev->disk->disk_name, dev->host);
         return;
     }
 
-    printk("INFO: Connecting device %s to %s\n", lo->disk->disk_name, lo->host);
+    printk("INFO: Connecting device %s to %s\n", dev->disk->disk_name, dev->host);
 
     // initialize socket
-    if (sock_create_kern(AF_INET, SOCK_STREAM, IPPROTO_TCP, &lo->sock) < 0)
+    if (sock_create_kern(AF_INET, SOCK_STREAM, IPPROTO_TCP, &dev->sock) < 0)
     {
         printk("ERROR: Couldn't create socket.\n");
-        lo->sock = NULL;
+        dev->sock = NULL;
         return;
     }
-    lo->sock->sk->sk_allocation = GFP_NOIO;
+    dev->sock->sk->sk_allocation = GFP_NOIO;
     sin.sin_family = AF_INET;
-    sin.sin_addr.s_addr = inet_addr(lo->host);
-    sin.sin_port = htons(simple_strtol(lo->port, NULL, 10));
-    if (kernel_connect(lo->sock, (struct sockaddr *) &sin, sizeof(sin), 0) < 0)
+    sin.sin_addr.s_addr = inet_addr(dev->host);
+    sin.sin_port = htons(simple_strtol(dev->port, NULL, 10));
+    if (kernel_connect(dev->sock, (struct sockaddr *) &sin, sizeof(sin), 0) < 0)
     {
-        printk("ERROR: Couldn't connect to host %s:%s\n", lo->host, lo->port);
-        lo->sock = NULL;
+        printk("ERROR: Couldn't connect to host %s:%s\n", dev->host, dev->port);
+        dev->sock = NULL;
         return;
     }
 
     // prepare message
     dnbd3_request.cmd = CMD_GET_SIZE;
-    dnbd3_request.vid = lo->vid;
-    dnbd3_request.rid = lo->rid;
+    dnbd3_request.vid = dev->vid;
+    dnbd3_request.rid = dev->rid;
     msg.msg_name = NULL;
     msg.msg_namelen = 0;
     msg.msg_control = NULL;
@@ -74,80 +75,82 @@ void dnbd3_net_connect(dnbd3_device_t *lo)
     // send message
     iov.iov_base = &dnbd3_request;
     iov.iov_len = sizeof(dnbd3_request);
-    kernel_sendmsg(lo->sock, &msg, &iov, 1, sizeof(dnbd3_request));
+    kernel_sendmsg(dev->sock, &msg, &iov, 1, sizeof(dnbd3_request));
 
     // receive replay
     iov.iov_base = &dnbd3_reply;
     iov.iov_len = sizeof(dnbd3_reply);
-    kernel_recvmsg(lo->sock, &msg, &iov, 1, sizeof(dnbd3_reply), msg.msg_flags);
-
-    // set filesize
-    if (dnbd3_reply.filesize <= 0)
+    kernel_recvmsg(dev->sock, &msg, &iov, 1, sizeof(dnbd3_reply), msg.msg_flags);
+    if (dnbd3_reply.size <= 0)
     {
         printk("ERROR: File size returned by server is < 0.\n");
-        sock_release(lo->sock);
-        lo->sock = NULL;
+        sock_release(dev->sock);
+        dev->sock = NULL;
         return;
     }
 
-    set_capacity(lo->disk, dnbd3_reply.filesize >> 9); /* 512 Byte blocks */
-    printk("INFO: Filesize %s: %llu\n", lo->disk->disk_name, dnbd3_reply.filesize);
+    // receive and set filesize
+    iov.iov_base = &filesize;
+    iov.iov_len = sizeof(uint64_t);
+    kernel_recvmsg(dev->sock, &msg, &iov, 1, dnbd3_reply.size, msg.msg_flags);
+    set_capacity(dev->disk, filesize >> 9); /* 512 Byte blocks */
+    printk("INFO: Filesize %s: %llu\n", dev->disk->disk_name, filesize);
 
     // start sending thread
-    lo->thread_send = kthread_create(dnbd3_net_send, lo, lo->disk->disk_name);
-    wake_up_process(lo->thread_send);
+    dev->thread_send = kthread_create(dnbd3_net_send, dev, dev->disk->disk_name);
+    wake_up_process(dev->thread_send);
 
     // start receiving thread
-    lo->thread_receive = kthread_create(dnbd3_net_receive, lo, lo->disk->disk_name);
-    wake_up_process(lo->thread_receive);
+    dev->thread_receive = kthread_create(dnbd3_net_receive, dev, dev->disk->disk_name);
+    wake_up_process(dev->thread_receive);
 
     // Add heartbeat timer
-    init_timer(&lo->hb_timer);
-    lo->hb_timer.data = (unsigned long) lo;
-    lo->hb_timer.function = dnbd3_net_heartbeat;
-    lo->hb_timer.expires = jiffies + HB_INTERVAL;
-    add_timer(&lo->hb_timer);
+    init_timer(&dev->hb_timer);
+    dev->hb_timer.data = (unsigned long) dev;
+    dev->hb_timer.function = dnbd3_net_heartbeat;
+    dev->hb_timer.expires = jiffies + HB_INTERVAL;
+    add_timer(&dev->hb_timer);
 }
 
-void dnbd3_net_disconnect(dnbd3_device_t *lo)
+void dnbd3_net_disconnect(dnbd3_device_t *dev)
 {
     struct request *blk_request, *tmp_request;
-    printk("INFO: Disconnecting device %s\n", lo->disk->disk_name);
+    printk("INFO: Disconnecting device %s\n", dev->disk->disk_name);
 
     // kill sending and receiving threads
-    if (lo->thread_send && lo->thread_receive)
+    if (dev->thread_send && dev->thread_receive)
     {
-        kthread_stop(lo->thread_send);
-        kthread_stop(lo->thread_receive);
+        kthread_stop(dev->thread_send);
+        kthread_stop(dev->thread_receive);
     }
 
     // clear sock
-    if (lo->sock)
+    if (dev->sock)
     {
-        sock_release(lo->sock);
-        lo->sock = NULL;
+        sock_release(dev->sock);
+        dev->sock = NULL;
     }
     // clear heartbeat timer
-    if (&lo->hb_timer)
-        del_timer(&lo->hb_timer);
+    if (&dev->hb_timer)
+        del_timer(&dev->hb_timer);
 
     // move already send requests to request_queue_send again
-    if (!list_empty(&lo->request_queue_receive))
+    if (!list_empty(&dev->request_queue_receive))
     {
-        printk("WARN: Request queue was not empty on %s\n", lo->disk->disk_name);
-        spin_lock_irq(&lo->blk_lock);
-        list_for_each_entry_safe(blk_request, tmp_request, &lo->request_queue_receive, queuelist)
+        printk("WARN: Request queue was not empty on %s\n", dev->disk->disk_name);
+        spin_lock_irq(&dev->blk_lock);
+        list_for_each_entry_safe(blk_request, tmp_request, &dev->request_queue_receive, queuelist)
         {
             list_del_init(&blk_request->queuelist);
-            list_add_tail(&blk_request->queuelist, &lo->request_queue_send);
+            list_add_tail(&blk_request->queuelist, &dev->request_queue_send);
         }
-        spin_unlock_irq(&lo->blk_lock);
+        spin_unlock_irq(&dev->blk_lock);
     }
 }
 
 int dnbd3_net_send(void *data)
 {
-    dnbd3_device_t *lo = data;
+    dnbd3_device_t *dev = data;
     dnbd3_request_t dnbd3_request;
     struct request *blk_request;
     struct msghdr msg;
@@ -161,24 +164,24 @@ int dnbd3_net_send(void *data)
 
     set_user_nice(current, -20);
 
-    while (!kthread_should_stop() || !list_empty(&lo->request_queue_send))
+    while (!kthread_should_stop() || !list_empty(&dev->request_queue_send))
     {
-        wait_event_interruptible(lo->process_queue_send,
-                kthread_should_stop() || !list_empty(&lo->request_queue_send));
+        wait_event_interruptible(dev->process_queue_send,
+                kthread_should_stop() || !list_empty(&dev->request_queue_send));
 
-        if (list_empty(&lo->request_queue_send))
+        if (list_empty(&dev->request_queue_send))
             continue;
 
         // extract block request
-        spin_lock_irq(&lo->blk_lock);
-        blk_request = list_entry(lo->request_queue_send.next, struct request, queuelist);
+        spin_lock_irq(&dev->blk_lock);
+        blk_request = list_entry(dev->request_queue_send.next, struct request, queuelist);
         list_del_init(&blk_request->queuelist);
-        spin_unlock_irq(&lo->blk_lock);
+        spin_unlock_irq(&dev->blk_lock);
 
         switch (blk_request->cmd_type)
         {
         case REQ_TYPE_SPECIAL:
-            dnbd3_request.cmd = CMD_PING;
+            dnbd3_request.cmd = CMD_GET_SERVERS;
             break;
 
         case REQ_TYPE_FS:
@@ -197,20 +200,20 @@ int dnbd3_net_send(void *data)
         iov.iov_len = sizeof(dnbd3_request);
 
         // send net request
-        if (kernel_sendmsg(lo->sock, &msg, &iov, 1, sizeof(dnbd3_request)) <= 0)
+        if (kernel_sendmsg(dev->sock, &msg, &iov, 1, sizeof(dnbd3_request)) <= 0)
             printk("ERROR: kernel_sendmsg\n");
 
-        spin_lock_irq(&lo->blk_lock);
-        list_add_tail(&blk_request->queuelist, &lo->request_queue_receive);
-        spin_unlock_irq(&lo->blk_lock);
-        wake_up(&lo->process_queue_receive);
+        spin_lock_irq(&dev->blk_lock);
+        list_add_tail(&blk_request->queuelist, &dev->request_queue_receive);
+        spin_unlock_irq(&dev->blk_lock);
+        wake_up(&dev->process_queue_receive);
     }
     return 0;
 }
 
 int dnbd3_net_receive(void *data)
 {
-    dnbd3_device_t *lo = data;
+    dnbd3_device_t *dev = data;
     dnbd3_reply_t dnbd3_reply;
     struct request *blk_request;
     struct msghdr msg;
@@ -223,6 +226,9 @@ int dnbd3_net_receive(void *data)
     void *kaddr;
     unsigned int size;
 
+    int i = 0;
+    char a[15];
+
     msg.msg_name = NULL;
     msg.msg_namelen = 0;
     msg.msg_control = NULL;
@@ -231,23 +237,23 @@ int dnbd3_net_receive(void *data)
 
     set_user_nice(current, -20);
 
-    while (!kthread_should_stop() || !list_empty(&lo->request_queue_receive))
+    while (!kthread_should_stop() || !list_empty(&dev->request_queue_receive))
     {
-        wait_event_interruptible(lo->process_queue_receive,
-                kthread_should_stop() || !list_empty(&lo->request_queue_receive));
+        wait_event_interruptible(dev->process_queue_receive,
+                kthread_should_stop() || !list_empty(&dev->request_queue_receive));
 
-        if (list_empty(&lo->request_queue_receive))
+        if (list_empty(&dev->request_queue_receive))
             continue;
 
         // receive net replay
         iov.iov_base = &dnbd3_reply;
         iov.iov_len = sizeof(dnbd3_reply);
-        kernel_recvmsg(lo->sock, &msg, &iov, 1, sizeof(dnbd3_reply), msg.msg_flags);
+        kernel_recvmsg(dev->sock, &msg, &iov, 1, sizeof(dnbd3_reply), msg.msg_flags);
 
         // search for replied request in queue
         received_request = *(struct request **) dnbd3_reply.handle;
-        spin_lock_irq(&lo->blk_lock);
-        list_for_each_entry_safe(blk_request, tmp_request, &lo->request_queue_receive, queuelist)
+        spin_lock_irq(&dev->blk_lock);
+        list_for_each_entry_safe(blk_request, tmp_request, &dev->request_queue_receive, queuelist)
         {
             if (blk_request != received_request)
             continue;
@@ -255,12 +261,22 @@ int dnbd3_net_receive(void *data)
             list_del_init(&blk_request->queuelist);
             break;
         }
-        spin_unlock_irq(&lo->blk_lock);
+        spin_unlock_irq(&dev->blk_lock);
 
         switch (dnbd3_reply.cmd)
         {
-        case CMD_PING:
-            // TODO: use for rtt?
+        case CMD_GET_SERVERS:
+            dev->num_servers = dnbd3_reply.size / sizeof(struct in_addr);
+            size = sizeof(struct in_addr);
+            for (i = 0; i < dev->num_servers && i < MAX_NUMBER_SERVERS; i++)
+            {
+                iov.iov_base = &dev->servers[i];
+                iov.iov_len = size;
+                kernel_recvmsg(dev->sock, &msg, &iov, 1, size, msg.msg_flags);
+
+//                inet_ntoa(dev->servers[i], a);
+//                printk("INFO: Server[%i] %s\n", i, a);
+            }
             break;
 
         case CMD_GET_BLOCK:
@@ -274,14 +290,14 @@ int dnbd3_net_receive(void *data)
                     size = bvec->bv_len;
                     iov.iov_base = kaddr;
                     iov.iov_len = size;
-                    kernel_recvmsg(lo->sock, &msg, &iov, 1, size, msg.msg_flags);
+                    kernel_recvmsg(dev->sock, &msg, &iov, 1, size, msg.msg_flags);
                     kunmap(bvec->bv_page);
 
                     sigprocmask(SIG_SETMASK, &oldset, NULL);
                 }
-            spin_lock_irqsave(&lo->blk_lock, flags);
+            spin_lock_irqsave(&dev->blk_lock, flags);
             __blk_end_request_all(blk_request, 0);
-            spin_unlock_irqrestore(&lo->blk_lock, flags);
+            spin_unlock_irqrestore(&dev->blk_lock, flags);
             break;
 
         default:
@@ -295,9 +311,9 @@ int dnbd3_net_receive(void *data)
 
 void dnbd3_net_heartbeat(unsigned long arg)
 {
-    dnbd3_device_t *lo = (dnbd3_device_t *) arg;
-    list_add(&lo->hb_request.queuelist, &lo->request_queue_send);
-    wake_up(&lo->process_queue_send);
-    lo->hb_timer.expires = jiffies + HB_INTERVAL;
-    add_timer(&lo->hb_timer);
+    dnbd3_device_t *dev = (dnbd3_device_t *) arg;
+    list_add(&dev->hb_request.queuelist, &dev->request_queue_send);
+    wake_up(&dev->process_queue_send);
+    dev->hb_timer.expires = jiffies + HB_INTERVAL;
+    add_timer(&dev->hb_timer);
 }
diff --git a/src/kernel/utils.c b/src/kernel/utils.c
index 85c0ce0..221dc4d 100644
--- a/src/kernel/utils.c
+++ b/src/kernel/utils.c
@@ -20,6 +20,8 @@
 
 #include <linux/kernel.h>
 
+#include "utils.h"
+
 unsigned int inet_addr(char *str)
 {
     int a, b, c, d;
@@ -31,3 +33,9 @@ unsigned int inet_addr(char *str)
     arr[3] = d;
     return *(unsigned int*) arr;
 }
+
+void inet_ntoa(struct in_addr addr, char* str)
+{
+    unsigned char *ptr = (unsigned char *) &addr;
+    sprintf(str, "%d.%d.%d.%d", ptr[0] & 0xff, ptr[1] & 0xff, ptr[2] & 0xff, ptr[3] & 0xff);
+}
diff --git a/src/kernel/utils.h b/src/kernel/utils.h
index 6b7fcee..b2c5fb1 100644
--- a/src/kernel/utils.h
+++ b/src/kernel/utils.h
@@ -21,6 +21,9 @@
 #ifndef UTILS_H_
 #define UTILS_H_
 
+#include <linux/in.h>
+
 unsigned int inet_addr(char *str);
+void inet_ntoa(struct in_addr addr, char* str);
 
 #endif /* UTILS_H_ */
diff --git a/src/server/net.c b/src/server/net.c
index f49305b..4f2ddfa 100644
--- a/src/server/net.c
+++ b/src/server/net.c
@@ -29,6 +29,7 @@
 #include <sys/sendfile.h>
 #include <sys/types.h>
 #include <netinet/in.h>
+#include <arpa/inet.h>
 
 #include "server.h"
 #include "utils.h"
@@ -36,20 +37,36 @@
 void *dnbd3_handle_query(void *dnbd3_client)
 {
     dnbd3_client_t *client = (dnbd3_client_t *) (uintptr_t) dnbd3_client;
-    int image_file = -1;
     dnbd3_request_t request;
     dnbd3_reply_t reply;
-    uint16_t cmd;
+
+    int image_file = -1;
+
+    struct in_addr server;
+    int i = 0;
 
     while (recv(client->sock, &request, sizeof(dnbd3_request_t), MSG_WAITALL) > 0)
     {
-        cmd = request.cmd;
-        switch (cmd)
+        reply.cmd = request.cmd;
+        memcpy(reply.handle, request.handle, sizeof(request.handle));
+
+        // TODO: lock CMD_GET_SERVERS and CMD_GET_SIZE because of reloading cfg...
+
+        switch (request.cmd)
         {
-        case CMD_PING:
-            reply.cmd = request.cmd;
-            memcpy(reply.handle, request.handle, sizeof(request.handle));
+        case CMD_GET_SERVERS:
+            if (client->image->num_servers < MAX_NUMBER_SERVERS)
+                reply.size = client->image->num_servers * sizeof(struct in_addr);
+            else
+                reply.size = MAX_NUMBER_SERVERS * sizeof(struct in_addr);
+
             send(client->sock, (char *) &reply, sizeof(dnbd3_reply_t), 0);
+
+            for (i = 0; i < client->image->num_servers && i < MAX_NUMBER_SERVERS; i++)
+            {
+                inet_aton(client->image->servers[i], &server);
+                send(client->sock, (char *) &server, sizeof(struct in_addr), 0);
+            }
             break;
 
         case CMD_GET_SIZE:
@@ -59,24 +76,23 @@ void *dnbd3_handle_query(void *dnbd3_client)
             if (image)
             {
                 image_file = open(image->file, O_RDONLY);
-                reply.filesize = image->filesize;
+                reply.size = sizeof(uint64_t);
                 client->image = image;
             }
             else
             {
                 printf("ERROR: Client requested an unknown image id.\n");
-                reply.filesize = 0;
+                reply.size = 0;
             }
-            reply.cmd = request.cmd;
             send(client->sock, (char *) &reply, sizeof(dnbd3_reply_t), 0);
+            send(client->sock, &image->filesize, sizeof(uint64_t), 0);
             break;
 
         case CMD_GET_BLOCK:
             if (image_file < 0)
                 break;
 
-            reply.cmd = request.cmd;
-            memcpy(reply.handle, request.handle, sizeof(request.handle));
+            reply.size = request.size;
             send(client->sock, (char *) &reply, sizeof(dnbd3_reply_t), 0);
 
             if (sendfile(client->sock, image_file, (off_t *) &request.offset, request.size) < 0)
diff --git a/src/server/server.c b/src/server/server.c
index bd09115..a767ed6 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -110,8 +110,10 @@ int main(int argc, char* argv[])
             demonize = 0;
             break;
         case 'r':
-            printf("INFO: Reloading configuration file...\n");
-            dnbd3_ipc_send(IPC_RELOAD);
+            printf("ERROR: Buggy, do not use...\n");
+            // FIXME: segfault in dnbd3_handle_query because of free(_images)
+            // printf("INFO: Reloading configuration file...\n");
+            // dnbd3_ipc_send(IPC_RELOAD);
             return EXIT_SUCCESS;
         case 's':
             printf("INFO: Stopping running server...\n");
diff --git a/src/server/server.h b/src/server/server.h
index dd8584c..02da005 100644
--- a/src/server/server.h
+++ b/src/server/server.h
@@ -31,9 +31,9 @@
 typedef struct
 {
     char *file;
-    off_t filesize;
+    uint64_t filesize;
+    size_t num_servers;
     char **servers;
-    size_t num;
     int vid;
     int rid;
 } dnbd3_image_t;
diff --git a/src/server/utils.c b/src/server/utils.c
index 34da129..3a9215e 100644
--- a/src/server/utils.c
+++ b/src/server/utils.c
@@ -45,10 +45,13 @@ void dnbd3_load_config(char *file)
     for (i = 0; i < _num_images; i++)
     {
         _images[i].file = g_key_file_get_string(gkf, groups[i], "file", NULL);
-        _images[i].servers = g_key_file_get_string_list(gkf, groups[i], "servers", &_images[i].num, NULL);
+        _images[i].servers = g_key_file_get_string_list(gkf, groups[i], "servers", &_images[i].num_servers, NULL);
         _images[i].vid = g_key_file_get_integer(gkf, groups[i], "vid", NULL);
         _images[i].rid = g_key_file_get_integer(gkf, groups[i], "rid", NULL);
 
+        if (_images[i].num_servers > MAX_NUMBER_SERVERS)
+            printf("WARN: Max allowed servers %i\n", MAX_NUMBER_SERVERS);
+
         fd = open(_images[i].file, O_RDONLY);
         if (fd > 0)
         {
diff --git a/src/types.h b/src/types.h
index bb2d082..8fdfbba 100644
--- a/src/types.h
+++ b/src/types.h
@@ -40,26 +40,26 @@ typedef struct
 // network
 #define CMD_GET_BLOCK   1
 #define CMD_GET_SIZE    2
-#define CMD_PING        3
+#define CMD_GET_SERVERS 3
 
 #pragma pack(1)
 typedef struct
 {
-    uint16_t cmd;
-    uint16_t vid;
-    uint16_t rid;
-    uint64_t offset;
-    uint64_t size;
-    char handle[8];
+    uint16_t cmd;       // 2byte
+    uint16_t vid;       // 2byte
+    uint16_t rid;       // 2byte
+    uint64_t offset;    // 8byte
+    uint64_t size;      // 8byte
+    char handle[8];     // 8byte
 } dnbd3_request_t;
 #pragma pack(0)
 
 #pragma pack(1)
 typedef struct
 {
-    uint16_t cmd;
-    uint64_t filesize;
-    char handle[8];
+    uint16_t cmd;   // 2byte
+    uint64_t size;  // 8byte
+    char handle[8]; // 8byte
 } dnbd3_reply_t;
 #pragma pack(0)