[SERVER] Check which dnbd3 devices are idle and ready to use for proxy mode

[SERVER] Skeleton of server-to-server communication
[SERVER] Update access-time of images in use by actual clients
[*] Add dnbd3_host_t type to handle address+port+addrtype consistently across the project

17 files changed, 511 insertions, 349 deletions

diff --git a/src/client/client.c b/src/client/client.c
index b94076f..397ac38 100644
--- a/src/client/client.c
+++ b/src/client/client.c
@@ -93,8 +93,8 @@ int main(int argc, char *argv[])
 	memset(&msg, 0, sizeof(dnbd3_ioctl_t));
 	msg.len = (uint16_t)sizeof(dnbd3_ioctl_t);
 	msg.read_ahead_kb = DEFAULT_READ_AHEAD_KB;
-	msg.port = htons(PORT);
-	msg.addrtype = 0;
+	msg.host.port = htons(PORT);
+	msg.host.type = 0;
 	msg.imgname = NULL;
 	msg.is_server = FALSE;
 
@@ -125,8 +125,8 @@ int main(int argc, char *argv[])
 			_config_file_name = strdup(optarg);
 			break;
 		case 'h':
-			dnbd3_get_ip(optarg, msg.addr, &msg.addrtype);
-			printf("Host set to %s (type %d)\n", inet_ntoa(*(struct in_addr *)msg.addr), (int)msg.addrtype);
+			dnbd3_get_ip(optarg, msg.host.addr, &msg.host.type);
+			printf("Host set to %s (type %d)\n", inet_ntoa(*(struct in_addr *)msg.host.addr), (int)msg.host.type);
 			break;
 		case 'i':
 			msg.imgname = strdup(optarg);
@@ -147,7 +147,7 @@ int main(int argc, char *argv[])
 			close_dev = 1;
 			break;
 		case 's':
-			dnbd3_get_ip(optarg, msg.addr, &msg.addrtype);
+			dnbd3_get_ip(optarg, msg.host.addr, &msg.host.type);
 			switch_host = 1;
 			break;
 		case 'H':
@@ -164,7 +164,7 @@ int main(int argc, char *argv[])
 	}
 
 	// close device
-	if (close_dev && msg.addrtype == 0 && dev && (msg.imgname == NULL))
+	if (close_dev && msg.host.type == 0 && dev && (msg.imgname == NULL))
 	{
 		fd = open(dev, O_WRONLY);
 		printf("INFO: Closing device %s\n", dev);
@@ -181,7 +181,7 @@ int main(int argc, char *argv[])
 	}
 
 	// switch host
-	if (switch_host && msg.addrtype != 0 && dev && (msg.imgname == NULL))
+	if (switch_host && msg.host.type != 0 && dev && (msg.imgname == NULL))
 	{
 		fd = open(dev, O_WRONLY);
 		printf("INFO: Switching device %s to %s\n", dev, "<fixme>");
@@ -198,7 +198,7 @@ int main(int argc, char *argv[])
 	}
 
 	// connect
-	if (msg.addrtype != 0 && dev && (msg.imgname != NULL))
+	if (msg.host.type != 0 && dev && (msg.imgname != NULL))
 	{
 		msg.imgnamelen = (uint16_t)strlen(msg.imgname);
 		fd = open(dev, O_WRONLY);
@@ -229,7 +229,7 @@ int main(int argc, char *argv[])
 
 		for (i = 0; i < j; i++)
 		{
-			dnbd3_get_ip(g_key_file_get_string(gkf, groups[i], "server", NULL), msg.addr, &msg.addrtype);
+			dnbd3_get_ip(g_key_file_get_string(gkf, groups[i], "server", NULL), msg.host.addr, &msg.host.type);
 			msg.imgname = g_key_file_get_string(gkf, groups[i], "name", NULL);
 			msg.rid = g_key_file_get_integer(gkf, groups[i], "rid", NULL);
 			dev = g_key_file_get_string(gkf, groups[i], "device", NULL);
diff --git a/src/kernel/blk.c b/src/kernel/blk.c
index bc138c3..4282295 100644
--- a/src/kernel/blk.c
+++ b/src/kernel/blk.c
@@ -140,9 +140,9 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 		}
 		else
 		{
-			memcpy(dev->cur_server.hostaddr, msg->addr, 16);
-			dev->cur_server.port = msg->port;
-			dev->cur_server.hostaddrtype = msg->addrtype;
+			if (sizeof(msg->host) != sizeof(dev->cur_server.host))
+				printk("Odd size bug#1 triggered in IOCTL\n");
+			memcpy(&dev->cur_server.host, &msg->host, sizeof(msg->host));
 			dev->cur_server.failures = 0;
 			memcpy(&dev->initial_server, &dev->cur_server, sizeof(dev->initial_server));
 			dev->imgname = imgname;
@@ -176,9 +176,7 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 
 	case IOCTL_SWITCH:
 		dnbd3_net_disconnect(dev);
-		memcpy(dev->cur_server.hostaddr, msg->addr, 16);
-		dev->cur_server.port = msg->port;
-		dev->cur_server.hostaddrtype = msg->addrtype;
+		memcpy(&dev->cur_server.host, &msg->host, sizeof(msg->host));
 		result = dnbd3_net_connect(dev);
 		break;
 
@@ -195,9 +193,7 @@ int dnbd3_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, u
 				result = -EAGAIN;
 			else
 			{
-				memcpy(dev->new_servers[dev->new_servers_num].hostaddr, msg->addr, 16);
-				dev->new_servers[dev->new_servers_num].port = msg->port;
-				dev->new_servers[dev->new_servers_num].hostaddrtype = msg->addrtype;
+				memcpy(&dev->new_servers[dev->new_servers_num].host, &msg->host, sizeof(msg->host));
 				dev->new_servers[dev->new_servers_num].failures = (cmd == IOCTL_ADD_SRV ? 0 : 1); // 0 = ADD, 1 = REM
 				++dev->new_servers_num;
 				result = 0;
diff --git a/src/kernel/dnbd3.h b/src/kernel/dnbd3.h
index fb83575..e7911cf 100644
--- a/src/kernel/dnbd3.h
+++ b/src/kernel/dnbd3.h
@@ -35,11 +35,9 @@ extern int major;
 
 typedef struct
 {
+	dnbd3_host_t host;
 	unsigned long rtts[4];		// Last four round trip time measurements in µs
-	uint16_t port;				// Port in network representation
 	uint16_t protocol_version;	// dnbd3 protocol version of this server
-	uint8_t hostaddr[16];		// Address in network representation (IPv4 or IPv6)
-	uint8_t hostaddrtype;		// Address type (AF_INET or AF_INET6)
 	uint8_t failures;			// How many times the server was unreachable
 } dnbd3_server_t;
 
diff --git a/src/kernel/net.c b/src/kernel/net.c
index 2cd3cac..f437464 100644
--- a/src/kernel/net.c
+++ b/src/kernel/net.c
@@ -36,34 +36,34 @@
  */
 #if 1 // Change to 0 to disable debug messages
 #define debug_print_va_host(_host, _fmt, ...) do { \
-	if (dev->cur_server.hostaddrtype == AF_INET) \
-		printk("%s:%d " _fmt " (%s, %pI4:%d)\n", __FILE__, __LINE__, __VA_ARGS__, dev->disk->disk_name, (_host).hostaddr, (int)ntohs((_host).port)); \
+	if ((_host).type == AF_INET) \
+		printk("%s:%d " _fmt " (%s, %pI4:%d)\n", __FILE__, __LINE__, __VA_ARGS__, dev->disk->disk_name, (_host).addr, (int)ntohs((_host).port)); \
 	else \
-		printk("%s:%d " _fmt " (%s, [%pI6]:%d)\n", __FILE__, __LINE__, __VA_ARGS__, dev->disk->disk_name, (_host).hostaddr, (int)ntohs((_host).port)); \
+		printk("%s:%d " _fmt " (%s, [%pI6]:%d)\n", __FILE__, __LINE__, __VA_ARGS__, dev->disk->disk_name, (_host).addr, (int)ntohs((_host).port)); \
 } while(0)
 #define debug_error_va_host(_host, _fmt, ...) do { \
 	debug_print_va_host(_host, _fmt, __VA_ARGS__); \
 	goto error; \
 } while(0)
-#define debug_dev_va(_fmt, ...) debug_print_va_host(dev->cur_server, _fmt, __VA_ARGS__)
-#define error_dev_va(_fmt, ...) debug_error_va_host(dev->cur_server, _fmt, __VA_ARGS__)
-#define debug_alt_va(_fmt, ...) debug_print_va_host(dev->alt_servers[i], _fmt, __VA_ARGS__)
-#define error_alt_va(_fmt, ...) debug_error_va_host(dev->alt_servers[i], _fmt, __VA_ARGS__)
+#define debug_dev_va(_fmt, ...) debug_print_va_host(dev->cur_server.host, _fmt, __VA_ARGS__)
+#define error_dev_va(_fmt, ...) debug_error_va_host(dev->cur_server.host, _fmt, __VA_ARGS__)
+#define debug_alt_va(_fmt, ...) debug_print_va_host(dev->alt_servers[i].host, _fmt, __VA_ARGS__)
+#define error_alt_va(_fmt, ...) debug_error_va_host(dev->alt_servers[i].host, _fmt, __VA_ARGS__)
 
 #define debug_print_host(_host, txt) do { \
-	if (dev->cur_server.hostaddrtype == AF_INET) \
-		printk("%s:%d " txt " (%s, %pI4:%d)\n", __FILE__, __LINE__, dev->disk->disk_name, (_host).hostaddr, (int)ntohs((_host).port)); \
+	if ((_host).type == AF_INET) \
+		printk("%s:%d " txt " (%s, %pI4:%d)\n", __FILE__, __LINE__, dev->disk->disk_name, (_host).addr, (int)ntohs((_host).port)); \
 	else \
-		printk("%s:%d " txt " (%s, [%pI6]:%d)\n", __FILE__, __LINE__, dev->disk->disk_name, (_host).hostaddr, (int)ntohs((_host).port)); \
+		printk("%s:%d " txt " (%s, [%pI6]:%d)\n", __FILE__, __LINE__, dev->disk->disk_name, (_host).addr, (int)ntohs((_host).port)); \
 } while(0)
 #define debug_error_host(_host, txt) do { \
 	debug_print_host(_host, txt); \
 	goto error; \
 } while(0)
-#define debug_dev(txt) debug_print_host(dev->cur_server, txt)
-#define error_dev(txt) debug_error_host(dev->cur_server, txt)
-#define debug_alt(txt) debug_print_host(dev->alt_servers[i], txt)
-#define error_alt(txt) debug_error_host(dev->alt_servers[i], txt)
+#define debug_dev(txt) debug_print_host(dev->cur_server.host, txt)
+#define error_dev(txt) debug_error_host(dev->cur_server.host, txt)
+#define debug_alt(txt) debug_print_host(dev->alt_servers[i].host, txt)
+#define error_alt(txt) debug_error_host(dev->alt_servers[i].host, txt)
 
 #else // Silent
 
@@ -79,9 +79,9 @@
 
 static inline int is_same_server(const dnbd3_server_t *const a, const dnbd3_server_t *const b)
 {
-	return (a->hostaddrtype == b->hostaddrtype)
-	       && (a->port == b->port)
-	       && (0 == memcmp(a->hostaddr, b->hostaddr, (a->hostaddrtype == AF_INET ? 4 : 16)));
+	return (a->host.type == b->host.type)
+	       && (a->host.port == b->host.port)
+	       && (0 == memcmp(a->host.addr, b->host.addr, (a->host.type == AF_INET ? 4 : 16)));
 }
 
 static inline dnbd3_server_t *get_existing_server(const dnbd3_server_entry_t *const newserver, dnbd3_device_t *const dev)
@@ -89,9 +89,9 @@ static inline dnbd3_server_t *get_existing_server(const dnbd3_server_entry_t *co
 	int i;
 	for (i = 0; i < NUMBER_SERVERS; ++i)
 	{
-		if ((newserver->hostaddrtype == dev->alt_servers[i].hostaddrtype)
-		        && (newserver->port == dev->alt_servers[i].port)
-		        && (0 == memcmp(newserver->hostaddr, dev->alt_servers[i].hostaddr, (newserver->hostaddrtype == AF_INET ? 4 : 16))))
+		if ((newserver->host.type == dev->alt_servers[i].host.type)
+		        && (newserver->host.port == dev->alt_servers[i].host.port)
+		        && (0 == memcmp(newserver->host.addr, dev->alt_servers[i].host.addr, (newserver->host.type == AF_INET ? 4 : 16))))
 		{
 			return &dev->alt_servers[i];
 			break;
@@ -105,7 +105,7 @@ static inline dnbd3_server_t *get_free_alt_server(dnbd3_device_t *const dev)
 	int i;
 	for (i = 0; i < NUMBER_SERVERS; ++i)
 	{
-		if (dev->alt_servers[i].hostaddrtype == 0)
+		if (dev->alt_servers[i].host.type == 0)
 			return &dev->alt_servers[i];
 	}
 	for (i = 0; i < NUMBER_SERVERS; ++i)
@@ -153,12 +153,12 @@ int dnbd3_net_connect(dnbd3_device_t *dev)
 			error_dev("FATAL: Kmalloc(1) failed.");
 	}
 
-	if (dev->cur_server.port == 0 || dev->cur_server.hostaddrtype == 0 || dev->imgname == NULL)
+	if (dev->cur_server.host.port == 0 || dev->cur_server.host.type == 0 || dev->imgname == NULL)
 		error_dev("FATAL: Host, port or image name not set.");
 	if (dev->sock)
 		error_dev("ERROR: Already connected.");
 
-	if (dev->cur_server.hostaddrtype != AF_INET)
+	if (dev->cur_server.host.type != AF_INET)
 		error_dev("ERROR: IPv6 not implemented.");
 	else
 		debug_dev("INFO: Connecting...");
@@ -180,8 +180,8 @@ int dnbd3_net_connect(dnbd3_device_t *dev)
 		kernel_setsockopt(dev->sock, SOL_SOCKET, SO_RCVTIMEO, (char *) &timeout, sizeof(timeout));
 		dev->sock->sk->sk_allocation = GFP_NOIO;
 		sin.sin_family = AF_INET;
-		memcpy(&(sin.sin_addr.s_addr), dev->cur_server.hostaddr, 4);
-		sin.sin_port = dev->cur_server.port;
+		memcpy(&(sin.sin_addr.s_addr), dev->cur_server.host.addr, 4);
+		sin.sin_port = dev->cur_server.host.port;
 		if (kernel_connect(dev->sock, (struct sockaddr *) &sin, sizeof(sin), 0) != 0)
 			error_dev("FATAL: Connection to host failed.");
 		// Request filesize
@@ -291,8 +291,8 @@ error:
 		sock_release(dev->sock);
 		dev->sock = NULL;
 	}
-	dev->cur_server.hostaddrtype = 0;
-	dev->cur_server.port = 0;
+	dev->cur_server.host.type = 0;
+	dev->cur_server.host.port = 0;
 	if (req1) kfree(req1);
 	return -1;
 }
@@ -337,8 +337,8 @@ int dnbd3_net_disconnect(dnbd3_device_t *dev)
 		sock_release(dev->sock);
 		dev->sock = NULL;
 	}
-	dev->cur_server.hostaddrtype = 0;
-	dev->cur_server.port = 0;
+	dev->cur_server.host.type = 0;
+	dev->cur_server.host.port = 0;
 
 	dev->disconnecting = 0;
 
@@ -451,7 +451,7 @@ int dnbd3_net_discover(void *data)
 			spin_lock_irqsave(&dev->blk_lock, irqflags);
 			for (i = 0; i < dev->new_servers_num; ++i)
 			{
-				if (dev->new_servers[i].hostaddrtype != AF_INET) // Invalid entry.. (Add IPv6)
+				if (dev->new_servers[i].host.type != AF_INET) // Invalid entry.. (Add IPv6)
 					continue;
 				alt_server = get_existing_server(&dev->new_servers[i], dev);
 				if (alt_server != NULL) // Server already known
@@ -459,7 +459,7 @@ int dnbd3_net_discover(void *data)
 					if (dev->new_servers[i].failures == 1)
 					{
 						// REMOVE request
-						alt_server->hostaddrtype = 0;
+						alt_server->host.type = 0;
 						continue;
 					}
 					// ADD, so just reset fail counter
@@ -472,9 +472,9 @@ int dnbd3_net_discover(void *data)
 				if (alt_server == NULL) // All NUMBER_SERVERS slots are taken, ignore entry
 					continue;
 				// Add new server entry
-				memcpy(alt_server->hostaddr, dev->new_servers[i].hostaddr, 16);
-				alt_server->hostaddrtype = dev->new_servers[i].hostaddrtype;
-				alt_server->port = dev->new_servers[i].port;
+				memcpy(alt_server->host.addr, dev->new_servers[i].host.addr, 16);
+				alt_server->host.type = dev->new_servers[i].host.type;
+				alt_server->host.port = dev->new_servers[i].host.port;
 				alt_server->rtts[0] = alt_server->rtts[1]
 				                      = alt_server->rtts[2] = alt_server->rtts[3]
 				                              = RTT_UNREACHABLE;
@@ -490,7 +490,7 @@ int dnbd3_net_discover(void *data)
 
 		for (i=0; i < NUMBER_SERVERS; ++i)
 		{
-			if (dev->alt_servers[i].hostaddrtype == 0) // Empty slot
+			if (dev->alt_servers[i].host.type == 0) // Empty slot
 				continue;
 			if (!dev->panic && dev->alt_servers[i].failures > 50) // If not in panic mode, skip server if it failed too many times
 				continue;
@@ -506,8 +506,8 @@ int dnbd3_net_discover(void *data)
 			kernel_setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char *) &timeout, sizeof(timeout));
 			sock->sk->sk_allocation = GFP_NOIO;
 			sin.sin_family = AF_INET; // add IPv6.....
-			memcpy(&sin.sin_addr.s_addr, dev->alt_servers[i].hostaddr, 4);
-			sin.sin_port = dev->alt_servers[i].port;
+			memcpy(&sin.sin_addr.s_addr, dev->alt_servers[i].host.addr, 4);
+			sin.sin_port = dev->alt_servers[i].host.port;
 			if (kernel_connect(sock, (struct sockaddr *) &sin, sizeof(sin), 0) < 0)
 				goto error;
 
@@ -565,7 +565,7 @@ int dnbd3_net_discover(void *data)
 			// panic mode, take first responding server
 			if (dev->panic)
 			{
-				printk("WARN: Panic mode (%s), taking server %pI4 : %d\n", dev->disk->disk_name, dev->alt_servers[i].hostaddr, (int)ntohs(dev->alt_servers[i].port));
+				debug_alt("WARN: Panic mode, changing server:");
 				if (best_sock != NULL) sock_release(best_sock);
 				dev->better_sock = sock; // Pass over socket to take a shortcut in *_connect();
 				kfree(buf);
@@ -796,7 +796,7 @@ int dnbd3_net_send(void *data)
 	return 0;
 
 error:
-	printk("ERROR: Connection to server %pI4 : %d lost (send)\n", dev->cur_server.hostaddr, (int)ntohs(dev->cur_server.port));
+	debug_dev("ERROR: Connection to server lost (send)");
 	if (dev->sock)
 		kernel_sock_shutdown(dev->sock, SHUT_RDWR);
 	dev->thread_send = NULL;
diff --git a/src/kernel/sysfs.c b/src/kernel/sysfs.c
index 596e745..d219c86 100644
--- a/src/kernel/sysfs.c
+++ b/src/kernel/sysfs.c
@@ -29,10 +29,10 @@
 
 ssize_t show_cur_server_addr(char *buf, dnbd3_device_t *dev)
 {
-	if (dev->cur_server.hostaddrtype == AF_INET)
-		return MIN(snprintf(buf, PAGE_SIZE, "%pI4,%d\n", dev->cur_server.hostaddr, (int)ntohs(dev->cur_server.port)), PAGE_SIZE);
-	else if (dev->cur_server.hostaddrtype == AF_INET6)
-		return MIN(snprintf(buf, PAGE_SIZE, "%pI6,%d\n", dev->cur_server.hostaddr, (int)ntohs(dev->cur_server.port)), PAGE_SIZE);
+	if (dev->cur_server.host.type == AF_INET)
+		return MIN(snprintf(buf, PAGE_SIZE, "%pI4,%d\n", dev->cur_server.host.addr, (int)ntohs(dev->cur_server.host.port)), PAGE_SIZE);
+	else if (dev->cur_server.host.type == AF_INET6)
+		return MIN(snprintf(buf, PAGE_SIZE, "%pI6,%d\n", dev->cur_server.host.addr, (int)ntohs(dev->cur_server.host.port)), PAGE_SIZE);
 	*buf = '\0';
 	return 0;
 }
@@ -47,7 +47,7 @@ ssize_t show_alt_server_num(char *buf, dnbd3_device_t *dev)
 	int i, num = 0;
 	for (i = 0; i < NUMBER_SERVERS; ++i)
 	{
-		if (dev->alt_servers[i].hostaddrtype) ++num;
+		if (dev->alt_servers[i].host.type) ++num;
 	}
 	return MIN(snprintf(buf, PAGE_SIZE, "%d\n", num), PAGE_SIZE);
 }
@@ -57,17 +57,17 @@ ssize_t show_alt_servers(char *buf, dnbd3_device_t *dev)
 	int i, size = PAGE_SIZE, ret;
 	for (i = 0; i < NUMBER_SERVERS; ++i)
 	{
-		if (dev->alt_servers[i].hostaddrtype == AF_INET)
+		if (dev->alt_servers[i].host.type == AF_INET)
 			ret = MIN(snprintf(buf, size, "%pI4,%d,%llu,%d\n",
-			                   dev->alt_servers[i].hostaddr,
-			                   (int)ntohs(dev->alt_servers[i].port),
+			                   dev->alt_servers[i].host.addr,
+			                   (int)ntohs(dev->alt_servers[i].host.port),
 			                   (unsigned long long)((dev->alt_servers[i].rtts[0] + dev->alt_servers[i].rtts[1] + dev->alt_servers[i].rtts[2] + dev->alt_servers[i].rtts[3]) / 4),
 			                   (int)dev->alt_servers[i].failures)
 			          , size);
-		else if (dev->alt_servers[i].hostaddrtype == AF_INET6)
+		else if (dev->alt_servers[i].host.type == AF_INET6)
 			ret = MIN(snprintf(buf, size, "%pI6,%d,%llu,%d\n",
-			                   dev->alt_servers[i].hostaddr,
-			                   (int)ntohs(dev->alt_servers[i].port),
+			                   dev->alt_servers[i].host.addr,
+			                   (int)ntohs(dev->alt_servers[i].host.port),
 			                   (unsigned long long)((dev->alt_servers[i].rtts[0] + dev->alt_servers[i].rtts[1] + dev->alt_servers[i].rtts[2] + dev->alt_servers[i].rtts[3]) / 4),
 			                   (int)dev->alt_servers[i].failures)
 			          , size);
diff --git a/src/server/helper.c b/src/server/helper.c
new file mode 100644
index 0000000..293fa36
--- /dev/null
+++ b/src/server/helper.c
@@ -0,0 +1,162 @@
+#include "helper.h"
+#include <arpa/inet.h>
+#include <string.h>
+#include <stdlib.h>
+#include <glib/gmacros.h>
+#include "../config.h"
+
+/**
+ * Parse IPv4 or IPv6 address in string representation to a suitable format usable by the BSD socket library
+ * @string eg. "1.2.3.4" or "2a01::10:5", optially with port appended, eg "1.2.3.4:6666" or "[2a01::10:5]:6666"
+ * @af will contain either AF_INET or AF_INET6
+ * @addr will contain the address in network representation
+ * @port will contain the port in network representation, defaulting to #define PORT if none was given
+ * returns 1 on success, 0 in failure. contents of af, addr and port are undefined in the latter case
+ * !! Contents of @string might be modified by this function !!
+ */
+char parse_address(char *string, dnbd3_host_t *host)
+{
+	struct in_addr v4;
+	struct in6_addr v6;
+
+	// Try IPv4 without port
+	if (1 == inet_pton(AF_INET, string, &v4))
+	{
+		host->type = AF_INET;
+		memcpy(host->addr, &v4, 4);
+		host->port = htons(PORT);
+		return 1;
+	}
+	// Try IPv6 without port
+	if (1 == inet_pton(AF_INET6, string, &v6))
+	{
+		host->type = AF_INET6;
+		memcpy(host->addr, &v6, 16);
+		host->port = htons(PORT);
+		return 1;
+	}
+
+	// Scan for port
+	char *portpos = NULL, *ptr = string;
+	while (*ptr)
+	{
+		if (*ptr == ':')
+			portpos = ptr;
+		++ptr;
+	}
+	if (portpos == NULL)
+		return 0; // No port in string
+	// Consider IP being surrounded by [ ]
+	if (*string == '[' && *(portpos - 1) == ']')
+	{
+		++string;
+		*(portpos - 1) = '\0';
+	}
+	*portpos++ = '\0';
+	int p = atoi(portpos);
+	if (p < 1 || p > 65535)
+		return 0; // Invalid port
+	host->port = htons((uint16_t)p);
+
+	// Try IPv4 with port
+	if (1 == inet_pton(AF_INET, string, &v4))
+	{
+		host->type = AF_INET;
+		memcpy(host->addr, &v4, 4);
+		return 1;
+	}
+	// Try IPv6 with port
+	if (1 == inet_pton(AF_INET6, string, &v6))
+	{
+		host->type = AF_INET6;
+		memcpy(host->addr, &v6, 16);
+		return 1;
+	}
+
+	// FAIL
+	return 0;
+}
+
+/**
+ * Convert a host and port (network byte order) to printable representation.
+ * Worst case required buffer len is 48, eg. [1234:1234:1234:1234:1234:1234:1234:1234]:12345 (+ \0)
+ * Returns TRUE on success, FALSE on error
+ */
+char host_to_string(const dnbd3_host_t *host, char *target, size_t targetlen)
+{
+	// Worst case: Port 5 chars, ':' to separate ip and port 1 char, terminating null 1 char = 7, [] for IPv6
+	if (targetlen < 10)
+		return FALSE;
+	if (host->type == AF_INET6)
+	{
+		*target++ = '[';
+		inet_ntop(AF_INET6, host->addr, target, targetlen - 9);
+		target += strlen(target);
+		*target++ = ']';
+	}
+	else if (host->type == AF_INET)
+	{
+		inet_ntop(AF_INET, host->addr, target, targetlen - 7);
+		target += strlen(target);
+	}
+	else
+	{
+		snprintf(target, targetlen, "<?addrtype=%d>", (int)host->type);
+		return FALSE;
+	}
+	*target = '\0';
+	if (host->port != 0)
+	{
+		// There are still at least 7 bytes left in the buffer, port is at most 5 bytes + ':' + '\0' = 7
+		snprintf(target, 7, ":%d", (int)ntohs(host->port));
+	}
+	return TRUE;
+}
+
+char is_valid_namespace(char *namespace)
+{
+	if (*namespace == '\0' || *namespace == '/')
+		return 0; // Invalid: Length = 0 or starting with a slash
+	while (*namespace)
+	{
+		if (*namespace != '/' && *namespace != '-' && (*namespace < 'a' || *namespace > 'z')
+		        && (*namespace < 'A' || *namespace > 'Z')
+		        && (*namespace < '0' || *namespace > '9'))
+			return 0;
+		++namespace;
+	}
+	if (strstr(namespace, "//") != NULL)
+		return 0; // Invalid: Double slash
+	if (*(namespace - 1) == '/')
+		return 0; // Invalid: Ends in a slash
+	return 1;
+}
+
+char is_valid_imagename(char *namespace)
+{
+	if (*namespace == '\0' || *namespace == ' ')
+		return 0; // Invalid: Length = 0 or starting with a space
+	while (*namespace)
+	{
+		// Check for invalid chars
+		if (*namespace != '.' && *namespace != '-' && *namespace != ' '
+		        && *namespace != '(' && *namespace != ')'
+		        && (*namespace < 'a' || *namespace > 'z') && (*namespace < 'A' || *namespace > 'Z')
+		        && (*namespace < '0' || *namespace > '9'))
+			return 0;
+		++namespace;
+	}
+	if (*(namespace - 1) == ' ')
+		return 0; // Invalid: Ends in a space
+	return 1;
+}
+
+void strtolower(char *string)
+{
+	while (*string)
+	{
+		if (*string >= 'A' && *string <= 'Z')
+			*string += 32;
+		++string;
+	}
+}
diff --git a/src/server/helper.h b/src/server/helper.h
new file mode 100644
index 0000000..e787c42
--- /dev/null
+++ b/src/server/helper.h
@@ -0,0 +1,30 @@
+#ifndef HELPER_H_
+#define HELPER_H_
+
+#include "server.h"
+#include <netinet/in.h>
+#include <string.h>
+
+char parse_address(char *string, dnbd3_host_t *host);
+char host_to_string(const dnbd3_host_t *host, char *target, size_t targetlen);
+char is_valid_namespace(char *namespace);
+char is_valid_imagename(char *namespace);
+void strtolower(char *string);
+
+static inline int is_same_server(const dnbd3_trusted_server_t *const a, const dnbd3_trusted_server_t *const b)
+{
+	return (a->host.type == b->host.type)
+	       && (a->host.port == b->host.port)
+	       && (0 == memcmp(a->host.addr, b->host.addr, (a->host.type == AF_INET ? 4 : 16)));
+}
+
+// one byte in the map covers 8 4kib blocks, so 32kib per byte
+// "+ (1 << 15) - 1" is required to account for the last bit of
+// the image that is smaller than 32kib
+// this would be the case whenever the image file size is not a
+// multiple of 32kib (= the number of blocks is not divisible by 8)
+// ie: if the image is 49152 bytes and you do 49152 >> 15 you get 1,
+// but you actually need 2 bytes to have a complete cache map
+#define IMGSIZE_TO_MAPBYTES(bytes) ((int)(((bytes) + (1 << 15) - 1) >> 15))
+
+#endif
diff --git a/src/server/ipc.c b/src/server/ipc.c
index 339dcc6..b93844a 100644
--- a/src/server/ipc.c
+++ b/src/server/ipc.c
@@ -18,6 +18,13 @@
  *
  */
 
+#include "ipc.h"
+#include "../config.h"
+#include "server.h"
+#include "saveload.h"
+#include "memlog.h"
+#include "helper.h"
+
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
@@ -37,12 +44,6 @@
 #include <libxml/xpath.h>
 #include "xmlutil.h"
 
-#include "ipc.h"
-#include "../config.h"
-#include "server.h"
-#include "utils.h"
-#include "memlog.h"
-
 #define IPC_PORT (PORT+1)
 
 static int server_sock = -1;
@@ -363,7 +364,6 @@ static int ipc_receive(int client_sock)
 {
 	GSList *iterator, *iterator2;
 
-	struct tm *timeinfo;
 #define STRBUFLEN 100
 	char strbuffer[STRBUFLEN];
 
@@ -433,8 +433,7 @@ static int ipc_receive(int client_sock)
 			if (tmp_node == NULL)
 				goto get_info_reply_cleanup;
 			xmlNewProp(tmp_node, BAD_CAST "name", BAD_CAST image->config_group);
-			timeinfo = localtime(&image->atime);
-			strftime(strbuffer, STRBUFLEN, "%d.%m.%y %H:%M:%S", timeinfo);
+			sprintf(strbuffer, "%u", (unsigned int)image->atime);
 			xmlNewProp(tmp_node, BAD_CAST "atime", BAD_CAST strbuffer);
 			sprintf(strbuffer, "%d", image->rid);
 			xmlNewProp(tmp_node, BAD_CAST "rid", BAD_CAST strbuffer);
@@ -471,7 +470,7 @@ static int ipc_receive(int client_sock)
 				if (tmp_node == NULL)
 					goto get_info_reply_cleanup;
 				*strbuffer = '\0';
-				inet_ntop(client->addrtype, client->ipaddr, strbuffer, STRBUFLEN);
+				host_to_string(&client->host, strbuffer, STRBUFLEN);
 				xmlNewProp(tmp_node, BAD_CAST "ip", BAD_CAST strbuffer);
 				xmlNewProp(tmp_node, BAD_CAST "file", BAD_CAST client->image->file);
 				xmlAddChild(parent_node, tmp_node);
@@ -490,15 +489,14 @@ static int ipc_receive(int client_sock)
 		for (iterator = _trusted_servers; iterator; iterator = iterator->next)
 		{
 			dnbd3_trusted_server_t *server = iterator->data;
-			if (server->hostaddrtype != 0)
+			if (server->host.type != 0)
 			{
 				tmp_node = xmlNewNode(NULL, BAD_CAST "server");
 				if (tmp_node == NULL)
 					goto get_info_reply_cleanup;
-				*strbuffer = '\0';
-				inet_ntop(server->hostaddrtype, server->hostaddr, strbuffer, STRBUFLEN);
+				host_to_string(&server->host, strbuffer, STRBUFLEN);
 				xmlNewProp(tmp_node, BAD_CAST "ip", BAD_CAST strbuffer);
-				sprintf(strbuffer, "%d", (int)server->port);
+				sprintf(strbuffer, "%d", (int)server->host.port);
 				xmlNewProp(tmp_node, BAD_CAST "port", BAD_CAST strbuffer);
 				if (server->comment)
 					xmlNewProp(tmp_node, BAD_CAST "comment", BAD_CAST server->comment);
@@ -576,32 +574,28 @@ get_info_reply_cleanup:
 
 			FOR_EACH_NODE(docRequest, "/data/images/image", cur)
 			{
-				if (cur->type == XML_ELEMENT_NODE)
+				if (cur->type != XML_ELEMENT_NODE)
+					continue;
+				NEW_POINTERLIST;
+				++count;
+				dnbd3_image_t image;
+				memset(&image, 0, sizeof(dnbd3_image_t));
+				image.config_group = (char *)XML_GETPROP(cur, "name");
+				char *rid_str = (char *)XML_GETPROP(cur, "rid");
+				image.file = (char *)XML_GETPROP(cur, "file");
+				image.cache_file = (char *)XML_GETPROP(cur, "cache");
+				if (image.config_group && rid_str && image.file && image.cache_file)
 				{
-					++count;
-					dnbd3_image_t image;
-					memset(&image, 0, sizeof(dnbd3_image_t));
-					image.config_group = (char *)xmlGetNoNsProp(cur, BAD_CAST "name");
-					char *rid_str = (char *)xmlGetNoNsProp(cur, BAD_CAST "rid");
-					image.file = (char *)xmlGetNoNsProp(cur, BAD_CAST "file");
-					image.cache_file = (char *)xmlGetNoNsProp(cur, BAD_CAST "cache");
-					if (image.config_group && rid_str && image.file && image.cache_file)
-					{
-						image.rid = atoi(rid_str);
-						if (cmd == IPC_ADDIMG)
-							header.error = htonl(dnbd3_add_image(&image));
-						else
-							header.error = htonl(dnbd3_del_image(&image));
-					}
+					image.rid = atoi(rid_str);
+					if (cmd == IPC_ADDIMG)
+						header.error = htonl(dnbd3_add_image(&image));
 					else
-						header.error = htonl(ERROR_MISSING_ARGUMENT);
-					xmlFree(image.config_group);
-					xmlFree(rid_str);
-					xmlFree(image.file);
-					xmlFree(image.cache_file);
+						header.error = htonl(dnbd3_del_image(&image));
 				}
-			}
-			END_FOR_EACH;
+				else
+					header.error = htonl(ERROR_MISSING_ARGUMENT);
+				FREE_POINTERLIST;
+			} END_FOR_EACH;
 			if (count == 0)
 				header.error = htonl(ERROR_MISSING_ARGUMENT);
 		}
@@ -712,22 +706,20 @@ void dnbd3_ipc_send(int cmd)
 				printf("--- Last log lines ----\n%s\n\n", log);
 			}
 
-			int watime = 0, wname = 0, wrid = 5;
+			int watime = 17, wname = 0, wrid = 5;
 			FOR_EACH_NODE(doc, "/data/images/image", cur)
 			{
 				if (cur->type != XML_ELEMENT_NODE)
 					continue;
-				xmlChar *atime = xmlGetNoNsProp(cur, BAD_CAST "atime");
-				xmlChar *vid = xmlGetNoNsProp(cur, BAD_CAST "name");
-				xmlChar *rid = xmlGetNoNsProp(cur, BAD_CAST "rid");
-				watime = MAX(watime, xmlStrlen(atime));
+				NEW_POINTERLIST; // This macro defines an array of pointers
+				xmlChar *vid = XML_GETPROP(cur, "name"); // XML_GETPROP is a macro wrapping xmlGetNoNsProp()
+				xmlChar *rid = XML_GETPROP(cur, "rid"); // Each of these calls allocates memory for the string
 				wname = MAX(wname, xmlStrlen(vid));
 				wrid = MAX(wrid, xmlStrlen(rid));
-				// Too lazy to free vars, client will exit anyways
-			}
-			END_FOR_EACH;
+				FREE_POINTERLIST; // This macro simply frees all pointers in the above array
+			} END_FOR_EACH;
 
-			char format[100];
+			char format[100], strbuffer[STRBUFLEN];
 			snprintf(format, 100,
 			         "%%-%ds %%-%ds %%%ds %%s\n", watime, wname, wrid);
 
@@ -740,15 +732,18 @@ void dnbd3_ipc_send(int cmd)
 			{
 				if (cur->type != XML_ELEMENT_NODE)
 					continue;
+				NEW_POINTERLIST;
 				++count;
-				xmlChar *atime = xmlGetNoNsProp(cur, BAD_CAST "atime");
-				xmlChar *vid = xmlGetNoNsProp(cur, BAD_CAST "name");
-				xmlChar *rid = xmlGetNoNsProp(cur, BAD_CAST "rid");
-				xmlChar *file = xmlGetNoNsProp(cur, BAD_CAST "file");
-				printf(format, atime, vid, rid, file);
-				// Too lazy to free vars, client will exit anyways
-			}
-			END_FOR_EACH;
+				xmlChar *numatime = XML_GETPROP(cur, "atime");
+				xmlChar *vid = XML_GETPROP(cur, "name");
+				xmlChar *rid = XML_GETPROP(cur, "rid");
+				xmlChar *file = XML_GETPROP(cur, "file");
+				time_t at = (time_t)atol((char*)numatime);
+				struct tm *timeinfo = localtime(&at);
+				strftime(strbuffer, STRBUFLEN, "%d.%m.%y %H:%M:%S", timeinfo);
+				printf(format, strbuffer, vid, rid, file);
+				FREE_POINTERLIST;
+			} END_FOR_EACH;
 			char_repeat_br('=', term_width);
 			printf("\nNumber of images: %d\n\n", count);
 
@@ -765,8 +760,7 @@ void dnbd3_ipc_send(int cmd)
 				xmlChar *file = xmlGetNoNsProp(cur, BAD_CAST "file");
 				printf("%-40s %s\n", ip, file);
 				// Too lazy to free vars, client will exit anyways
-			}
-			END_FOR_EACH;
+			} END_FOR_EACH;
 			char_repeat_br('=', term_width);
 			printf("\nNumber clients: %d\n\n", count);
 
@@ -778,30 +772,32 @@ void dnbd3_ipc_send(int cmd)
 			{
 				if (cur->type != XML_ELEMENT_NODE)
 					continue;
+				NEW_POINTERLIST;
 				++count;
-				xmlChar *ip = xmlGetNoNsProp(cur, BAD_CAST "ip");
-				xmlChar *comment = xmlGetNoNsProp(cur, BAD_CAST "comment");
+				xmlChar *ip = XML_GETPROP(cur, "ip");
+				xmlChar *comment = XML_GETPROP(cur, "comment");
 				if (comment)
 					printf("%-30s (%s)\n", ip, comment);
 				else
 					printf("%-30s\n", ip);
 				for (childit = cur->children; childit; childit = childit->next)
 				{
-					if (childit->type != XML_ELEMENT_NODE || childit->name == NULL || strcmp(childit->name, "namespace") != 0)
+					if (childit->type != XML_ELEMENT_NODE || childit->name == NULL || strcmp((const char*)childit->name, "namespace") != 0)
 						continue;
-					xmlChar *name = xmlGetNoNsProp(childit, BAD_CAST "name");
-					xmlChar *replicate = xmlGetNoNsProp(childit, BAD_CAST "replicate");
-					xmlChar *recursive = xmlGetNoNsProp(childit, BAD_CAST "recursive");
+					NEW_POINTERLIST;
+					xmlChar *name = XML_GETPROP(childit, "name");
+					xmlChar *replicate = XML_GETPROP(childit, "replicate");
+					xmlChar *recursive = XML_GETPROP(childit, "recursive");
 					printf("     %-40s ", name);
 					if (replicate && *replicate != '0')
 						printf(" replicate");
 					if (recursive && *recursive != '0')
 						printf(" recursive");
 					putchar('\n');
+					FREE_POINTERLIST;
 				}
-				// Too lazy to free vars, client will exit anyways
-			}
-			END_FOR_EACH;
+				FREE_POINTERLIST;
+			} END_FOR_EACH;
 			char_repeat_br('=', term_width);
 			printf("\nNumber servers: %d\n\n", count);
 
diff --git a/src/server/ipc.h b/src/server/ipc.h
index 36d1f60..fb29efc 100644
--- a/src/server/ipc.h
+++ b/src/server/ipc.h
@@ -21,6 +21,8 @@
 #ifndef IPC_H_
 #define IPC_H_
 
+#include <stdint.h>
+
 #define IPC_EXIT 0
 #define IPC_RELOAD 1
 #define IPC_INFO 2
diff --git a/src/server/job.c b/src/server/job.c
index 1f10cb6..4a30cd1 100644
--- a/src/server/job.c
+++ b/src/server/job.c
@@ -1,5 +1,7 @@
 #include "job.h"
-#include "utils.h"
+#include "saveload.h"
+#include "memlog.h"
+
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -7,8 +9,15 @@
 #include <string.h>
 #include <pthread.h>
 #include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
 #include <glib/gslist.h>
 
+#include <libxml/parser.h>
+#include <libxml/xpath.h>
+#include "xmlutil.h"
+
 #define DEV_STRLEN 12 // INCLUDING NULLCHAR (increase to 13 if you need more than 100 (0-99) devices)
 #define MAX_NUM_DEVICES_TO_CHECK 100
 
@@ -34,6 +43,7 @@ static char keep_running = TRUE;
 // Private functions
 static char *get_free_device();
 static void query_servers();
+static void update_image_atimes(time_t now);
 
 //
 
@@ -73,7 +83,8 @@ void *dnbd3_job_thread(void *data)
 	{
 		const time_t starttime = time(NULL);
 		//
-		// TODO: Update image atime
+		// Update image atime
+		update_image_atimes(starttime);
 		// Call image deletion function if last call is more than 5 minutes ago
 		if (starttime < next_delete_invocation)
 		{
@@ -99,32 +110,116 @@ void dnbd3_job_shutdown()
 	keep_running = FALSE;
 }
 
+static void update_image_atimes(time_t now)
+{
+	GSList *iterator;
+	pthread_spin_lock(&_spinlock);
+	for (iterator = _dnbd3_clients; iterator; iterator = iterator->next)
+	{
+		dnbd3_client_t *client = iterator->data;
+		if (client && client->image && !client->is_server)
+			client->image->atime = now;
+	}
+	pthread_spin_unlock(&_spinlock);
+}
+
 static void query_servers()
 {
-	struct timeval client_timeout;
+	if (_trusted_servers == NULL)
+		return;
+	struct timeval client_timeout, connect_timeout;
 	client_timeout.tv_sec = 0;
 	client_timeout.tv_usec = 500 * 1000;
-	int client_sock;
-	// Apply read/write timeout
-	setsockopt(client_sock, SOL_SOCKET, SO_RCVTIMEO, &client_timeout, sizeof(client_timeout));
-	setsockopt(client_sock, SOL_SOCKET, SO_SNDTIMEO, &client_timeout, sizeof(client_timeout));
+	connect_timeout.tv_sec = 2;
+	connect_timeout.tv_usec = 0;
+	int client_sock, num;
+	dnbd3_trusted_server_t *server;
+	dnbd3_host_t host;
+	struct sockaddr_in addr4;
+	for (num = 0;; ++num)
+	{
+		// "Iterate" this way to prevent holding the lock for a long time, although it is possible to skip a server this way...
+		pthread_spin_lock(&_spinlock);
+		server = g_slist_nth_data(_trusted_servers, num);
+		if (server == NULL)
+		{
+			pthread_spin_unlock(&_spinlock);
+			break; // Done
+		}
+		memcpy(&host, &server->host, sizeof(host));
+		pthread_spin_unlock(&_spinlock);
+		// Connect
+		if (host.type != AF_INET)
+		{
+			printf("[DEBUG] Unsupported addr type '%d', ignoring trusted server.\n", (int)host.type);
+			continue;
+		}
+		// Create socket (Extend for IPv6)
+		if ((client_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
+		{
+			printf("[DEBUG] Error creating server-to-server socket.\n");
+			continue;
+		}
+		// Set host (IPv4)
+		memset(&addr4, 0, sizeof(addr4));
+		addr4.sin_family = AF_INET;
+		memcpy(&addr4.sin_addr.s_addr, host.addr, 4);
+		addr4.sin_port = host.port;
+		// Connect to server
+		setsockopt(client_sock, SOL_SOCKET, SO_RCVTIMEO, &connect_timeout, sizeof(connect_timeout));
+		setsockopt(client_sock, SOL_SOCKET, SO_SNDTIMEO, &connect_timeout, sizeof(connect_timeout));
+		if (connect(client_sock, (struct sockaddr *)&addr4, sizeof(addr4)) < 0)
+		{
+			printf("[DEBUG] Could not connect to other server...\n");
+			close(client_sock); // TODO: Remove from alt server list if failed too often
+			continue;
+		}
+		// Apply read/write timeout
+		setsockopt(client_sock, SOL_SOCKET, SO_RCVTIMEO, &client_timeout, sizeof(client_timeout));
+		setsockopt(client_sock, SOL_SOCKET, SO_SNDTIMEO, &client_timeout, sizeof(client_timeout));
+		//
+		// TODO: Send and receive info from server
+		//
+		close(client_sock);
+		//
+		// TODO: Process data, update server info, add/remove this server as alt server for images, replicate images, etc.
+	}
 }
 
 /**
  * Get full name of an available dnbd3 device, eg. /dev/dnbd4
  * Returned buffer is owned by this module, do not modify or free!
+ * Returns NULL if all devices are in use
  */
 static char *get_free_device()
 {
 	if (devices == NULL)
 		return NULL;
-	int i;
+	int i, c;
+	char buffer[100];
 	for (i = 0; i < num_devices; ++i)
 	{
 		if (!devices[i].available)
 			continue;
-		// TODO: Check sysfs if device is maybe already connected
+		devices[i].available = FALSE;
+		// Check sysfs if device is maybe already connected
+		snprintf(buffer, 100, "/sys/devices/virtual/block/%s/net/cur_server_addr", devices[i].name + 5);
+		FILE *f = fopen(buffer, "r");
+		if (f == NULL)
+		{
+			printf("[DEBUG] Could not open %s - device marked as used.\n", buffer);
+			continue;
+		}
+		c = fgetc(f);
+		fclose(f);
+		if (c > 0)
+		{
+			// Could read something, so the device is connected
+			printf("[DEBUG] Free device %s is actually in use - marked as such.\n", devices[i].name);
+			continue;
+		}
 		return devices[i].name;
 	}
+	memlogf("[WARNING] No more free dnbd3 devices - proxy mode probably affected.");
 	return NULL;
 }
diff --git a/src/server/net.c b/src/server/net.c
index afb7077..963d3ea 100644
--- a/src/server/net.c
+++ b/src/server/net.c
@@ -33,7 +33,7 @@
 #include <netinet/tcp.h>
 
 #include "server.h"
-#include "utils.h"
+#include "saveload.h"
 #include "memlog.h"
 #include "../serialize.h"
 #include "../config.h"
@@ -369,7 +369,7 @@ void *dnbd3_handle_query(void *dnbd3_client)
 				num = 0;
 				for (i = 0; i < NUMBER_SERVERS; i++)
 				{
-					if (image->servers[i].hostaddrtype == 0 || image->servers[i].failures > 200) continue;
+					if (image->servers[i].host.type == 0 || image->servers[i].failures > 200) continue;
 					memcpy(server_list + num++, image->servers + i, sizeof(dnbd3_server_entry_t));
 				}
 				reply.cmd = CMD_GET_SERVERS;
diff --git a/src/server/utils.c b/src/server/saveload.c
index ad40322..6af9b39 100644
--- a/src/server/utils.c
+++ b/src/server/saveload.c
@@ -24,147 +24,20 @@
 #include <pthread.h>
 #include <string.h>
 #include <glib.h>
+#include <math.h>
 #include <netinet/in.h>
-#include <arpa/inet.h>
 
 #include "server.h"
-#include "utils.h"
+#include "saveload.h"
 #include "memlog.h"
+#include "helper.h"
 
 // Keep parsed config file in memory so it doesn't need to be parsed again every time it's modified
 static GKeyFile *_config_handle = NULL;
 
-static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *port);
-static char is_valid_namespace(char *namespace);
-static char is_valid_imagename(char *namespace);
-static void strtolower(char *string);
-static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file, gchar **servers, gsize num_servers);
-static int save_config();
+static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file);
 //static char* get_local_image_name(char *global_name);
 
-/**
- * Parse IPv4 or IPv6 address in string representation to a suitable format usable by the BSD socket library
- * @string eg. "1.2.3.4" or "2a01::10:5", optially with port appended, eg "1.2.3.4:6666" or "[2a01::10:5]:6666"
- * @af will contain either AF_INET or AF_INET6
- * @addr will contain the address in network representation
- * @port will contain the port in network representation, defaulting to #define PORT if none was given
- * returns 1 on success, 0 in failure. contents of af, addr and port are undefined in the latter case
- */
-static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *port)
-{
-	struct in_addr v4;
-	struct in6_addr v6;
-
-	// Try IPv4 without port
-	if (1 == inet_pton(AF_INET, string, &v4))
-	{
-		*af = AF_INET;
-		memcpy(addr, &v4, 4);
-		*port = htons(PORT);
-		return 1;
-	}
-	// Try IPv6 without port
-	if (1 == inet_pton(AF_INET6, string, &v6))
-	{
-		*af = AF_INET6;
-		memcpy(addr, &v6, 16);
-		*port = htons(PORT);
-		return 1;
-	}
-
-	// Scan for port
-	char *portpos = NULL, *ptr = string;
-	while (*ptr)
-	{
-		if (*ptr == ':')
-			portpos = ptr;
-		++ptr;
-	}
-	if (portpos == NULL)
-		return 0; // No port in string
-	// Consider IP being surrounded by [ ]
-	if (*string == '[' && *(portpos - 1) == ']')
-	{
-		++string;
-		*(portpos - 1) = '\0';
-	}
-	*portpos++ = '\0';
-	int p = atoi(portpos);
-	if (p < 1 || p > 65535)
-		return 0; // Invalid port
-	*port = htons((uint16_t)p);
-
-	// Try IPv4 with port
-	if (1 == inet_pton(AF_INET, string, &v4))
-	{
-		*af = AF_INET;
-		memcpy(addr, &v4, 4);
-		return 1;
-	}
-	// Try IPv6 with port
-	if (1 == inet_pton(AF_INET6, string, &v6))
-	{
-		*af = AF_INET6;
-		memcpy(addr, &v6, 16);
-		return 1;
-	}
-
-	// FAIL
-	return 0;
-}
-
-static char is_valid_namespace(char *namespace)
-{
-	if (*namespace == '\0' || *namespace == '/')
-		return 0; // Invalid: Length = 0 or starting with a slash
-	while (*namespace)
-	{
-		if (*namespace != '/' && *namespace != '-' && (*namespace < 'a' || *namespace > 'z')
-		        && (*namespace < 'A' || *namespace > 'Z')
-		        && (*namespace < '0' || *namespace > '9'))
-			return 0;
-		++namespace;
-	}
-	if (*(namespace - 1) == '/')
-		return 0; // Invalid: Ends in a slash
-	return 1;
-}
-
-static char is_valid_imagename(char *namespace)
-{
-	if (*namespace == '\0' || *namespace == ' ')
-		return 0; // Invalid: Length = 0 or starting with a space
-	while (*namespace)
-	{
-		// Check for invalid chars
-		if (*namespace != '.' && *namespace != '-' && *namespace != ' '
-		        && *namespace != '(' && *namespace != ')'
-		        && (*namespace < 'a' || *namespace > 'z') && (*namespace < 'A' || *namespace > 'Z')
-		        && (*namespace < '0' || *namespace > '9'))
-			return 0;
-		++namespace;
-	}
-	if (*(namespace - 1) == ' ')
-		return 0; // Invalid: Ends in a space
-	return 1;
-}
-
-static inline int is_same_server(const dnbd3_trusted_server_t *const a, const dnbd3_trusted_server_t *const b)
-{
-	return (a->hostaddrtype == b->hostaddrtype)
-	       && (a->port == b->port)
-	       && (0 == memcmp(a->hostaddr, b->hostaddr, (a->hostaddrtype == AF_INET ? 4 : 16)));
-}
-
-static void strtolower(char *string)
-{
-	while (*string)
-	{
-		if (*string >= 'A' && *string <= 'Z')
-			*string += 32;
-		++string;
-	}
-}
 
 void dnbd3_load_config()
 {
@@ -191,6 +64,8 @@ void dnbd3_load_config()
 		_local_namespace = NULL;
 	}
 
+	srand(time(NULL));
+
 	_ipc_password = g_key_file_get_string(_config_handle, "settings", "password", NULL);
 
 	gchar **groups = NULL;
@@ -209,11 +84,10 @@ void dnbd3_load_config()
 			gchar *addr = g_key_file_get_string(_config_handle, groups[i], "address", NULL);
 			if (addr == NULL)
 				continue;
-			dnbd3_trusted_server_t *server = dnbd3_get_trusted_server(addr, TRUE);
+			dnbd3_trusted_server_t *server = dnbd3_get_trusted_server(addr, TRUE, groups[i]+6);
 			g_free(addr);
 			if (server == NULL)
 				continue;
-			server->comment = strdup(groups[i]+6);
 			gsize key_count;
 			gchar **keys = g_key_file_get_keys(_config_handle, groups[i], &key_count, NULL);
 			for (j = 0; j < key_count; ++j)
@@ -248,10 +122,8 @@ void dnbd3_load_config()
 
 		char *image_file = g_key_file_get_string(_config_handle, groups[i], "file", NULL);
 		char *cache_file = g_key_file_get_string(_config_handle, groups[i], "cache", NULL);
-		gsize num_servers;
-		gchar **servers = g_key_file_get_string_list(_config_handle, groups[i], "servers", &num_servers, NULL);
 
-		dnbd3_image_t *image = prepare_image(groups[i], rid, image_file, cache_file, servers, num_servers);
+		dnbd3_image_t *image = prepare_image(groups[i], rid, image_file, cache_file);
 		if (image)
 		{
 			_dnbd3_images = g_slist_prepend(_dnbd3_images, image);
@@ -259,7 +131,6 @@ void dnbd3_load_config()
 
 		g_free(image_file);
 		g_free(cache_file);
-		g_strfreev(servers);
 	}
 
 	g_strfreev(groups);
@@ -280,7 +151,7 @@ int dnbd3_add_image(dnbd3_image_t *image)
 			image->rid = 1;
 	}
 
-	dnbd3_image_t *newimage = prepare_image(image->config_group, image->rid, image->file, image->cache_file, NULL, 0);
+	dnbd3_image_t *newimage = prepare_image(image->config_group, image->rid, image->file, image->cache_file);
 	if (newimage)
 	{
 		_dnbd3_images = g_slist_prepend(_dnbd3_images, image);
@@ -299,7 +170,7 @@ int dnbd3_add_image(dnbd3_image_t *image)
 
 	pthread_spin_unlock(&_spinlock);
 
-	const int ret = save_config();
+	const int ret = dnbd3_save_config();
 	if (ret == ERROR_OK)
 		memlogf("[INFO] Added new image '%s' (rid %d)", newimage->config_group, newimage->rid);
 	else
@@ -328,7 +199,7 @@ int dnbd3_del_image(dnbd3_image_t *image)
 	dnbd3_exec_delete(FALSE);
 	existing_image = NULL;
 
-	const int ret = save_config();
+	const int ret = dnbd3_save_config();
 	if (ret == ERROR_OK)
 		memlogf("[INFO] Marked for deletion: '%s' (rid %d)", image->config_group, image->rid);
 	else
@@ -336,7 +207,7 @@ int dnbd3_del_image(dnbd3_image_t *image)
 	return ret;
 }
 
-static int save_config()
+int dnbd3_save_config()
 {
 	pthread_spin_lock(&_spinlock);
 	char *data = (char *)g_key_file_to_data(_config_handle, NULL, NULL);
@@ -408,12 +279,12 @@ dnbd3_image_t *dnbd3_get_image(char *name_orig, int rid, const char do_lock)
 
 void dnbd3_handle_sigpipe(int signum)
 {
-	memlogf("ERROR: SIGPIPE received!\n");
+	memlogf("ERROR: SIGPIPE received (%s)", strsignal(signum));
 }
 
 void dnbd3_handle_sigterm(int signum)
 {
-	memlogf("INFO: SIGTERM or SIGINT received!\n");
+	memlogf("INFO: SIGTERM or SIGINT received (%s)", strsignal(signum));
 	dnbd3_cleanup();
 }
 
@@ -423,9 +294,9 @@ void dnbd3_handle_sigterm(int signum)
  * Note: This function calls dnbd3_get_image without locking, so make sure you lock
  * before calling this function while the server is active.
  */
-static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file, gchar **servers, gsize num_servers)
+static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file)
 {
-	int j, k;
+	int j;
 	if (image_name == NULL)
 	{
 		memlogf("[ERROR] Null Image-Name");
@@ -511,19 +382,6 @@ static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file,
 		image->working = 1;
 	}
 
-	// A list of servers that are known to also host or relay this image
-	if (servers)
-		for (k = 0, j = 0; j < MIN(num_servers, NUMBER_SERVERS); ++j)
-		{
-			if (parse_address(servers[j], &(image->servers[k].hostaddrtype), image->servers[k].hostaddr,
-			                  &(image->servers[k].port)))
-			{
-				++k;
-				continue;
-			}
-			image->servers[k].hostaddrtype = 0;
-		}
-
 	if (image->cache_file)
 	{
 		// Determine size of cached image
@@ -637,7 +495,7 @@ void dnbd3_exec_delete(int save_if_changed)
 					continue;
 				// Kill client's connection
 				*ipstr = '\0';
-				inet_ntop(client->addrtype, client->ipaddr, ipstr, 100);
+				host_to_string(&client->host, ipstr, 100);
 				memlogf("[INFO] delete_hard of %s reached; dropping client %s", image->config_group, ipstr);
 				const int fd = client->sock;
 				client->sock = -1;
@@ -645,7 +503,7 @@ void dnbd3_exec_delete(int save_if_changed)
 				delete_now = FALSE; // Wait for all clients being actually dropped; deletion will happen on next dnbd3_exec_delete()
 			}
 		} // END delete_hard image
-		else if (image->delete_soft != 0 && image->delete_soft < now)
+		else if (image->delete_soft != 0 && image->delete_soft < now && image->atime + 3600 < now)
 		{
 			// Image should be soft-deleted
 			// Check if it is still in use
@@ -683,7 +541,7 @@ void dnbd3_exec_delete(int save_if_changed)
 	pthread_spin_lock(&_spinlock);
 
 	if (changed && save_if_changed)
-		save_config();
+		dnbd3_save_config();
 }
 
 /**
@@ -693,11 +551,11 @@ void dnbd3_exec_delete(int save_if_changed)
  * Returns NULL otherwise, or if the address could not be parsed
  * !! Lock before calling this function !!
  */
-dnbd3_trusted_server_t *dnbd3_get_trusted_server(char *address, char create_if_not_found)
+dnbd3_trusted_server_t *dnbd3_get_trusted_server(char *address, char create_if_not_found, char *comment)
 {
 	dnbd3_trusted_server_t server;
 	memset(&server, 0, sizeof(server));
-	if (!parse_address(address, &server.hostaddrtype, server.hostaddr, &server.port))
+	if (!parse_address(address, &server.host))
 	{
 		memlogf("[WARNING] Could not parse address '%s' of trusted server", address);
 		return NULL;
@@ -711,6 +569,22 @@ dnbd3_trusted_server_t *dnbd3_get_trusted_server(char *address, char create_if_n
 	}
 	if (!create_if_not_found)
 		return NULL;
+	char *groupname = NULL;
+	if (comment == NULL)
+	{
+		groupname = malloc(50);
+		snprintf(groupname, 50, "trust:%x%x", rand(), (int)clock());
+	}
+	else
+	{
+		const size_t len = strlen(comment) + 8;
+		groupname = malloc(len);
+		snprintf(groupname, len, "trust:%s", comment);
+	}
+	char addrbuffer[50];
+	host_to_string(&server.host, addrbuffer, 50);
+	g_key_file_set_string(_config_handle, groupname, "address", addrbuffer);
+	free(groupname);
 	dnbd3_trusted_server_t *copy = malloc(sizeof(server));
 	memcpy(copy, &server, sizeof(*copy));
 	_trusted_servers = g_slist_prepend(_trusted_servers, copy);
diff --git a/src/server/utils.h b/src/server/saveload.h
index e254cfd..065c0b1 100644
--- a/src/server/utils.h
+++ b/src/server/saveload.h
@@ -42,6 +42,8 @@
 #define ERROR_WRONG_PASSWORD           12
 
 void dnbd3_load_config();
+int dnbd3_save_config();
+
 int dnbd3_add_image(dnbd3_image_t *image);
 int dnbd3_del_image(dnbd3_image_t *image);
 
@@ -49,7 +51,7 @@ void dnbd3_exec_delete(int save_if_changed);
 
 dnbd3_image_t *dnbd3_get_image(char *name, int rid, const char do_lock);
 
-dnbd3_trusted_server_t *dnbd3_get_trusted_server(char *address, char create_if_not_found);
+dnbd3_trusted_server_t *dnbd3_get_trusted_server(char *address, char create_if_not_found, char *comment);
 int dnbd3_add_trusted_namespace(dnbd3_trusted_server_t *server, char *namespace, char *flags);
 
 void dnbd3_handle_sigpipe(int signum);
diff --git a/src/server/server.c b/src/server/server.c
index 9fc5383..4b30009 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -31,7 +31,7 @@
 #include "../version.h"
 
 #include "server.h"
-#include "utils.h"
+#include "saveload.h"
 #include "net.h"
 #include "ipc.h"
 #include "memlog.h"
@@ -245,10 +245,11 @@ int main(int argc, char *argv[])
 			continue;
 		}
 		// TODO: Extend this if you ever want to add IPv6 (something like:)
-		// dnbd3_client->addrtype = AF_INET6;
-		// memcpy(dnbd3_client->ipaddr, &(client.sin6_addr), 16);
-		dnbd3_client->addrtype = AF_INET;
-		memcpy(dnbd3_client->ipaddr, &(client.sin_addr), 4);
+		// dnbd3_client->host.type = AF_INET6;
+		// memcpy(dnbd3_client->host.addr, &(client.sin6_addr), 16);
+		dnbd3_client->host.type = AF_INET;
+		memcpy(dnbd3_client->host.addr, &(client.sin_addr), 4);
+		dnbd3_client->host.port = client.sin_port;
 		dnbd3_client->sock = fd;
 		dnbd3_client->image = NULL;
 
diff --git a/src/server/server.h b/src/server/server.h
index c608066..93f219e 100644
--- a/src/server/server.h
+++ b/src/server/server.h
@@ -28,37 +28,28 @@
 #include "../config.h"
 #include "../types.h"
 
-// one byte in the map covers 8 4kib blocks, so 32kib per byte
-// "+ (1 << 15) - 1" is required to account for the last bit of
-// the image that is smaller than 32kib
-// this would be the case whenever the image file size is not a
-// multiple of 32kib (= the number of blocks is not divisible by 8)
-// ie: if the image is 49152 bytes and you do 49152 >> 15 you get 1,
-// but you actually need 2 bytes to have a complete cache map
-#define IMGSIZE_TO_MAPBYTES(bytes) ((int)(((bytes) + (1 << 15) - 1) >> 15))
 
 typedef struct
 {
-	char *config_group; // exact name of group in config file that represents this image
-	char *low_name; // full (global) name of image, lowercased for comparison, eg. "uni-freiburg/rz/ubuntu-12.04"
-	int rid; // revision of provided image
-	char *file; // path to image file or device
-	uint64_t filesize; // size of image
+	char *config_group;    // exact name of group in config file that represents this image
+	char *low_name;        // full (global) name of image, lowercased for comparison, eg. "uni-freiburg/rz/ubuntu-12.04"
+	int rid;               // revision of provided image
+	char *file;            // path to image file or device
+	uint64_t filesize;     // size of image
 	dnbd3_server_entry_t servers[NUMBER_SERVERS]; // known alt servers that also offer that image
-	time_t atime; // last access time
-	uint8_t *cache_map; // cache map telling which parts are locally cached
-	char *cache_file; // path to local cache of image (in case the image is read from a dnbd3 device)
-	char working;	// whether this image is considered working. local images are "working" if the local file exists, proxied images have to have at least one working upstream server or a complete local cache file
-	time_t delete_soft; // unixtime telling when this image should be deleted. if there are still clients using this image it weill be kept, but new clients requesting the image will be rejected. 0 = never
-	time_t delete_hard; // unixtime telling when this image should be deleted, no matter if there are still clients connected. 0 = never
-	uint8_t relayed;		// TRUE if relayed from other server (needs dnbd3 client module loaded)
+	time_t atime;          // last access time
+	uint8_t *cache_map;    // cache map telling which parts are locally cached
+	char *cache_file;      // path to local cache of image (in case the image is read from a dnbd3 device)
+	char working;          // whether this image is considered working. local images are "working" if the local file exists, proxied images have to have at least one working upstream server or a complete local cache file
+	time_t delete_soft;    // unixtime telling when this image should be deleted. if there are still clients using this image it weill be kept, but new clients requesting the image will be rejected. 0 = never
+	time_t delete_hard;    // unixtime telling when this image should be deleted, no matter if there are still clients connected. 0 = never
+	uint8_t relayed;       // TRUE if relayed from other server (needs dnbd3 client module loaded)
 } dnbd3_image_t;
 
 typedef struct
 {
 	int sock;
-	uint8_t ipaddr[16];
-	uint8_t addrtype; 	       // ip version (AF_INET or AF_INET6)
+	dnbd3_host_t host;
 	uint8_t is_server;         // TRUE if a server in proxy mode, FALSE if real client
 	pthread_t thread;
 	dnbd3_image_t *image;
@@ -66,11 +57,9 @@ typedef struct
 
 typedef struct
 {
-	uint8_t  hostaddr[16];
-	uint16_t port;
-	uint8_t  hostaddrtype;
+	dnbd3_host_t host;
 	gchar    *comment;
-	GSList   *namespaces; // List of dnbd3_namespace_t
+	GSList   *namespaces;    // List of dnbd3_namespace_t
 } dnbd3_trusted_server_t;
 
 typedef struct
diff --git a/src/server/xmlutil.h b/src/server/xmlutil.h
index 46a5790..971d8a9 100644
--- a/src/server/xmlutil.h
+++ b/src/server/xmlutil.h
@@ -22,5 +22,17 @@ xmlChar *getTextFromPath(xmlDocPtr doc, char *xpath);
 	xmlXPathFreeContext(_makro_xpathCtx); \
 	} while(0)
 
+#define NUM_POINTERS_IN_LIST 20
+#define NEW_POINTERLIST \
+	void *_makro_ptrlist[NUM_POINTERS_IN_LIST]; \
+	int _makro_usedcount = 0
+
+#define FREE_POINTERLIST do { \
+	int _makro_i_; \
+	for (_makro_i_ = 0; _makro_i_ < _makro_usedcount; ++_makro_i_) { \
+		xmlFree(_makro_ptrlist[_makro_i_]); \
+	} } while(0)
+
+#define XML_GETPROP(_node, _name) (xmlChar*)(_makro_ptrlist[(_makro_usedcount >= NUM_POINTERS_IN_LIST ? 0 : _makro_usedcount++)] = xmlGetNoNsProp(_node, BAD_CAST _name))
 
 #endif
diff --git a/src/types.h b/src/types.h
index d41111a..22fbc50 100644
--- a/src/types.h
+++ b/src/types.h
@@ -60,12 +60,19 @@ static const uint16_t dnbd3_packet_magic = (0x73) | (0x72 << 8);
 #error "Unknown Endianness"
 #endif
 
+#pragma pack(1)
+typedef struct
+{
+	uint8_t addr[16];	   // 16byte (network representation, so it can be directly passed to socket functions)
+	uint16_t port;		   // 2byte (network representation, so it can be directly passed to socket functions)
+	uint8_t type;        // 1byte (ip version. AF_INET or AF_INET6. 0 means this struct is empty and should be ignored)
+} dnbd3_host_t;
+#pragma pack(0)
+
 typedef struct
 {
 	uint16_t len;
-	uint8_t addrtype;
-	uint8_t addr[16];	   // network representation
-	uint16_t port;		   // network representation
+	dnbd3_host_t host;
 	uint16_t imgnamelen;
 	char *imgname;
 	int rid;
@@ -106,10 +113,8 @@ typedef struct
 #pragma pack(1)
 typedef struct
 {
-	uint8_t hostaddr[16];	// 16byte (network representation, so it can be directly passed to socket functions)
-	uint16_t port; 			// 2byte (network representation, so it can be directly passed to socket functions)
-	uint8_t hostaddrtype; 	// 1byte (ip version. AF_INET or AF_INET6. 0 means this struct is empty and should be ignored)
-	uint8_t failures;		// 1byte (number of times server has been consecutively unreachable)
+	dnbd3_host_t host;
+	uint8_t  failures;		// 1byte (number of times server has been consecutively unreachable)
 } dnbd3_server_entry_t;
 #pragma pack(0)