[FUSE] Mid-refactoring, does not compile

15 files changed, 360 insertions, 86 deletions

diff --git a/src/config.h b/src/config.h
index 271e4bc..3ec0f8b 100644
--- a/src/config.h
+++ b/src/config.h
@@ -25,7 +25,7 @@
 // ########### SERVER ###########
 
 // +++++ Performance related
-#define SERVER_MAX_CLIENTS 2000
+#define SERVER_MAX_CLIENTS 400
 #define SERVER_MAX_IMAGES  5000
 #define SERVER_MAX_ALTS    250
 #define SERVER_MAX_UPLINK_QUEUE  1500
diff --git a/src/fuse/connection.c b/src/fuse/connection.c
index 039c532..cdfc1df 100644
--- a/src/fuse/connection.c
+++ b/src/fuse/connection.c
@@ -3,21 +3,28 @@
 #include "../config.h"
 #include "../shared/protocol.h"
 #include "../shared/signal.h"
+#include "../shared/sockhelper.h"
 
 #include <pthread.h>
 #include <string.h>
 #include <stdio.h>
 #include <unistd.h>
+#include <errno.h>
+#include <time.h>
 
 /* Constants */
 static const size_t SHORTBUF = 100;
 #define MAX_ALTS (8)
+#define MAX_HOSTS_PER_ADDRESS (2)
+static const int MAX_CONSECUTIVE_FAILURES = 16;
+#define RTT_COUNT (4)
 
 /* Module variables */
 
 // Init guard
 static bool initDone = false;
 static pthread_mutex_t mutexInit = PTHREAD_MUTEX_INITIALIZER;
+static bool keepRunning = true;
 
 // List of pending requests
 static struct {
@@ -31,14 +38,23 @@ static struct {
 	char *name;
 	uint16_t rid;
 	uint64_t size;
+} image;
+
+static struct {
 	int sockFd;
 	pthread_mutex_t sendMutex;
 	pthread_t receiveThread;
-} image;
+	int panicSignalFd;
+	bool panicMode;
+} connection;
 
 // Known alt servers
 static struct _alt_server {
-
+	dnbd3_host_t host;
+	int consecutiveFails;
+	int rtt;
+	int rtts[RTT_COUNT];
+	int rttIndex;
 } altservers[MAX_ALTS];
 typedef struct _alt_server alt_server_t;
 
@@ -47,22 +63,28 @@ typedef struct _alt_server alt_server_t;
 
 static void* connection_receiveThreadMain(void *sock);
 
+static void probeAltServers();
 static bool throwDataAway(int sockFd, uint32_t amount);
 static void enqueueRequest(dnbd3_async_t *request);
 static dnbd3_async_t* removeRequest(dnbd3_async_t *request);
+static uint64_t nowMilli();
+static uint64_t nowMicro();
 
 bool connection_init(const char *hosts, const char *lowerImage, const uint16_t rid)
 {
 	int sock = -1;
 	char host[SHORTBUF];
-	const char *current, *end;
 	serialized_buffer_t buffer;
 	uint16_t remoteVersion, remoteRid;
 	char *remoteName;
 	uint64_t remoteSize;
 
 	pthread_mutex_lock( &mutexInit );
-	if ( !initDone ) {
+	if ( !initDone && keepRunning ) {
+		dnbd3_host_t tempHosts[MAX_HOSTS_PER_ADDRESS];
+		const char *current, *end;
+		int altIndex = 0;
+		memset( altservers, 0, sizeof altservers );
 		current = hosts;
 		do {
 			// Get next host from string
@@ -71,9 +93,23 @@ bool connection_init(const char *hosts, const char *lowerImage, const uint16_t r
 			size_t len = (end == NULL ? SHORTBUF : (size_t)( end - current ) + 1);
 			if ( len > SHORTBUF ) len = SHORTBUF;
 			snprintf( host, len, "%s", current );
+			int newHosts = sock_resolveToDnbd3Host( host, tempHosts, MAX_HOSTS_PER_ADDRESS );
+			for ( int i = 0; i < newHosts; ++i ) {
+				if ( altIndex >= MAX_ALTS )
+					break;
+				altservers[altIndex].host = tempHosts[i];
+				altIndex += 1;
+			}
 			current = end + 1;
+		} while ( end != NULL && altIndex < MAX_ALTS );
+		printf( "Got %d servers from init call\n", altIndex );
+		// Connect
+		for ( int i = 0; i < altIndex; ++i ) {
+			if ( altservers[i].host.type == 0 )
+				continue;
 			// Try to connect
-			sock = connect_to_server( host, PORT ); // TODO: Parse port from host
+			sock = sock_connect( &altservers[i].host, 500, SOCKET_KEEPALIVE_TIMEOUT * 2000 ); // TODO timeout...
+			printf( "Got socket %d\n", sock );
 			if ( sock != -1 && dnbd3_select_image( sock, lowerImage, rid, 0 )
 					&& dnbd3_select_image_reply( &buffer, sock, &remoteVersion, &remoteName, &remoteRid, &remoteSize )
 					&& ( rid == 0 || rid == remoteRid ) ) {
@@ -87,16 +123,18 @@ bool connection_init(const char *hosts, const char *lowerImage, const uint16_t r
 				close( sock );
 				sock = -1;
 			}
-			// TODO: Add to alt list
-		} while ( end != NULL );
+		}
 		if ( sock != -1 ) {
-			if ( pthread_mutex_init( &image.sendMutex, NULL ) != 0
+			printf( "Initializing stuff\n" );
+			if ( pthread_mutex_init( &connection.sendMutex, NULL ) != 0
 					|| pthread_spin_init( &requests.lock, PTHREAD_PROCESS_PRIVATE ) != 0
-					|| pthread_create( &image.receiveThread, NULL, &connection_receiveThreadMain, (void*)(size_t)sock ) != 0 ) {
+					|| pthread_create( &connection.receiveThread, NULL, &connection_receiveThreadMain, (void*)(size_t)sock ) != 0 ) {
 				close( sock );
 				sock = -1;
 			} else {
-				image.sockFd = sock;
+				connection.sockFd = sock;
+				connection.panicMode = false;
+				connection.panicSignalFd = signal_new();
 				requests.head = NULL;
 				requests.tail = NULL;
 			}
@@ -111,31 +149,42 @@ bool connection_read(dnbd3_async_t *request)
 {
 	if (!initDone) return false;
 	enqueueRequest( request );
-	pthread_mutex_lock( &image.sendMutex );
-	if ( image.sockFd != -1 ) {
-		while ( !dnbd3_get_block( image.sockFd, request->offset, request->length, (uint64_t)request ) ) {
-			shutdown( image.sockFd, SHUT_RDWR );
-			image.sockFd = -1;
+	pthread_mutex_lock( &connection.sendMutex );
+	if ( connection.sockFd != -1 ) {
+		while ( !dnbd3_get_block( connection.sockFd, request->offset, request->length, (uint64_t)request ) ) {
+			shutdown( connection.sockFd, SHUT_RDWR );
+			connection.sockFd = -1;
 			// TODO reconnect!
-			pthread_mutex_unlock( &image.sendMutex );
+			pthread_mutex_unlock( &connection.sendMutex );
 			return false;
 		}
 	}
-	pthread_mutex_unlock( &image.sendMutex );
+	pthread_mutex_unlock( &connection.sendMutex );
 	return true;
 }
 
 void connection_close()
 {
-	//
+	pthread_mutex_lock( &mutexInit );
+	keepRunning = false;
+	if ( !initDone ) {
+		pthread_mutex_unlock( &mutexInit );
+		return;
+	}
+	pthread_mutex_unlock( &mutexInit );
+	pthread_mutex_lock( &connection.sendMutex );
+	if ( connection.sockFd != -1 ) {
+		shutdown( connection.sockFd, SHUT_RDWR );
+	}
+	pthread_mutex_unlock( &connection.sendMutex );
 }
 
 static void* connection_receiveThreadMain(void *sockPtr)
 {
 	int sockFd = (int)(size_t)sockPtr;
 	dnbd3_reply_t reply;
-	for ( ;; ) {
-		if ( !dnbd3_get_reply( image.sockFd, &reply ) )
+	while ( keepRunning ) {
+		if ( !dnbd3_get_reply( connection.sockFd, &reply ) )
 			goto fail;
 		// TODO: Ignoring anything but block replies for now; handle the others
 		if ( reply.cmd != CMD_GET_BLOCK ) {
@@ -167,26 +216,152 @@ static void* connection_receiveThreadMain(void *sockPtr)
 	}
 fail:;
 	// Make sure noone is trying to use the socket for sending by locking,
-	pthread_mutex_lock( &image.sendMutex );
+	pthread_mutex_lock( &connection.sendMutex );
 	// then just set the fd to -1, but only if it's the same fd as ours,
 	// as someone could have established a new connection already
-	if ( image.sockFd == sockFd ) {
-		image.sockFd = -1;
+	if ( connection.sockFd == sockFd ) {
+		connection.sockFd = -1;
 	}
-	pthread_mutex_unlock( &image.sendMutex );
+	pthread_mutex_unlock( &connection.sendMutex );
 	// As we're the only reader, it's safe to close the socket now
 	close( sockFd );
 	return NULL;
 }
 
+static void* connection_backgroundThread(void *something UNUSED)
+{
+	uint64_t nextKeepalive = 0;
+	uint64_t nextRttCheck = 0;
+	const uint64_t startupTime = nowMilli();
+
+	while ( keepRunning ) {
+		const uint64_t now = nowMilli();
+		if ( now < nextKeepalive && now < nextRttCheck ) {
+			int waitTime = (int)( MIN( nextKeepalive, nextRttCheck ) - now );
+			int waitRes = signal_wait( connection.panicSignalFd, waitTime );
+			if ( waitRes == SIGNAL_ERROR ) {
+				printf( "Error waiting on signal in background thread! Errno = %d\n", errno );
+			}
+		}
+		// Woken up, see what we have to do
+		// Check alt servers
+		if ( connection.panicMode || now < nextRttCheck ) {
+			probeAltServers();
+			if ( connection.panicMode || startupTime + ( STARTUP_MODE_DURATION * 1000ull ) > now ) {
+				nextRttCheck = now + TIMER_INTERVAL_PROBE_STARTUP * 1000ull;
+			} else {
+				nextRttCheck = now + TIMER_INTERVAL_PROBE_NORMAL * 1000ull;
+			}
+		}
+		// Send keepalive packet
+		if ( now < nextKeepalive ) {
+			pthread_mutex_lock( &connection.sendMutex );
+			if ( connection.sockFd != -1 ) {
+				printf( "Sending keepalive...\n" );
+				dnbd3_request_t request;
+				request.magic = dnbd3_packet_magic;
+				request.cmd = CMD_KEEPALIVE;
+				request.size = 0;
+				fixup_request( request );
+				ssize_t ret = sock_sendAll( connection.sockFd, &request, sizeof request, 2 );
+				if ( (size_t)ret != sizeof request ) {
+					shutdown( connection.sockFd, SHUT_RDWR );
+					connection.sockFd = -1;
+					connection.panicMode = true;
+				}
+			}
+			pthread_mutex_unlock( &connection.sendMutex );
+			nextKeepalive = now + TIMER_INTERVAL_KEEPALIVE_PACKET * 1000ull;
+		}
+	}
+	return NULL;
+}
+
 // Private quick helpers
 
+static void probeAltServers()
+{
+	serialized_buffer_t buffer;
+	dnbd3_request_t request;
+	dnbd3_reply_t reply;
+	int bestIndex = -1;
+	int bestSock = -1;
+	uint16_t remoteRid, remoteProto;
+	uint64_t remoteSize;
+	char *remoteName;
+
+	for ( int altIndex = 0; altIndex < MAX_ALTS; ++altIndex ) {
+		alt_server_t * const srv = &altservers[altIndex];
+		if ( srv->host.type == 0 )
+			continue;
+		if ( !connection.panicMode && srv->consecutiveFails > MAX_CONSECUTIVE_FAILURES
+				&& srv->consecutiveFails % ( srv->consecutiveFails / 8 ) != 0 ) {
+			continue;
+		}
+		if (srv->rttIndex >= RTT_COUNT) {
+			srv->rttIndex = 0;
+		} else {
+			srv->rttIndex += 1;
+		}
+		// Probe
+		const uint64_t start = nowMicro();
+		int sock = sock_connect( &srv->host, connection.panicMode ? 1000 : 333, 1000 );
+		if ( sock == -1 ) {
+			printf( "Could not crrate socket for probing. errno = %d\n", errno );
+			continue;
+		}
+		if ( !dnbd3_select_image( sock, image.name, image.rid, 0 ) ) {
+			goto fail;
+		}
+		if ( !dnbd3_select_image_reply( &buffer, sock, &remoteProto, &remoteName, &remoteRid, &remoteSize )) {
+			goto fail;
+		}
+		if ( remoteProto < MIN_SUPPORTED_SERVER || remoteProto > PROTOCOL_VERSION ) {
+			printf( "Unsupported remote version\n" );
+			goto fail;
+		}
+		if ( remoteRid != image.rid || strcmp( remoteName, image.name ) != 0 ) {
+			printf( "Remote rid or name mismatch\n" );
+			goto fail;
+		}
+		if ( !dnbd3_get_block( sock, 0, RTT_BLOCK_SIZE, 0 ) ) {
+			goto fail;
+		}
+		if ( !dnbd3_get_reply( sock, &reply ) || reply.size != RTT_BLOCK_SIZE
+				|| !throwDataAway( sock, RTT_BLOCK_SIZE ) ) {
+			goto fail;
+		}
+		// Yay, success
+		const uint64_t end = nowMicro();
+		srv->consecutiveFails = 0;
+		srv->rtts[srv->rttIndex] = (int)(end - start);
+		srv->rtt = 0;
+		for ( int i = 0; i < RTT_COUNT; ++i ) {
+			srv->rtt += srv->rtts[i];
+		}
+		srv->rtt /= RTT_COUNT;
+		if ( bestIndex == -1 || altservers[bestIndex].rtt > srv->rtt ) {
+			bestIndex = altIndex;
+			close( bestSock );
+			bestSock = sock;
+		} else {
+			close( sock );
+		}
+		continue; // XXX: Remember current server, compare to it, update value on change,
+fail:;
+		close( sock );
+		srv->rtts[srv->rttIndex] = RTT_UNREACHABLE;
+		srv->consecutiveFails += 1;
+	}
+}
+
 static bool throwDataAway(int sockFd, uint32_t amount)
 {
 	uint32_t done = 0;
 	char tempBuffer[SHORTBUF];
 	while ( done < amount ) {
-		if ( recv( sockFd, tempBuffer, MIN( amount - done, SHORTBUF ), 0 ) <= 0 )
+		const ssize_t ret = recv( sockFd, tempBuffer, MIN( amount - done, SHORTBUF ), MSG_NOSIGNAL );
+		if ( ret == 0 || ( ret < 0 && ret != EINTR ) )
 			return false;
 	}
 	return true;
@@ -227,3 +402,23 @@ static dnbd3_async_t* removeRequest(dnbd3_async_t *request)
 	pthread_spin_unlock( &requests.lock );
 	return iterator;
 }
+
+static uint64_t nowMilli()
+{
+	struct timespec ts;
+	if ( clock_gettime( CLOCK_MONOTONIC_RAW, &ts ) != 0 ) {
+		printf( "clock_gettime() failed. Errno: %d\n", errno );
+		return 0;
+	}
+	return ( ts.tv_sec * 1000ull ) + ( ts.tv_nsec / 1000000ull );
+}
+
+static uint64_t nowMicro()
+{
+	struct timespec ts;
+	if ( clock_gettime( CLOCK_MONOTONIC_RAW, &ts ) != 0 ) {
+		printf( "clock_gettime() failed. Errno: %d\n", errno );
+		return 0;
+	}
+	return ( ts.tv_sec * 1000000ull ) + ( ts.tv_nsec / 1000ull );
+}
diff --git a/src/fuse/helper.c b/src/fuse/helper.c
index 65644f8..6e46352 100644
--- a/src/fuse/helper.c
+++ b/src/fuse/helper.c
@@ -47,54 +47,3 @@ bool sock_printable( struct sockaddr *addr, socklen_t addrLen, char *output, int
 	}
 	return ret == 0;
 }
-
-// TODO: Pretty much same as in server/*
-int connect_to_server( char *server_address, int port )
-{
-	const int on = 1;
-	int sock = -1;
-	struct addrinfo hints, *res, *ptr;
-	char portStr[6];
-
-	// Set hints for local addresses.
-	memset( &hints, 0, sizeof( hints ) );
-	hints.ai_flags = AI_PASSIVE;
-	hints.ai_family = AF_UNSPEC;
-	hints.ai_socktype = SOCK_STREAM;
-	snprintf( portStr, sizeof portStr, "%d", port );
-	if ( getaddrinfo( server_address, portStr, &hints, &res ) != 0 || res == NULL ) {
-		return false;
-	}
-	// Attempt to bind to all of the addresses as long as there's room in the poll list
-	for ( ptr = res; ptr != NULL; ptr = ptr->ai_next ) {
-		char bla[100];
-		if ( !sock_printable( ( struct sockaddr * ) ptr->ai_addr, ptr->ai_addrlen, bla, 100 ) ) {
-			snprintf( bla, 100, "[invalid]" );
-		}
-		printf( "Trying to connect to %s ", bla );
-		sock = socket( ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol );
-		if ( sock < 0 ) {
-			printf( "...cannot create socket, errno=%d\n", errno );
-			sock = -1;
-			continue;
-		}
-		setsockopt( sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof( on ) );
-		if ( ptr->ai_family == PF_INET6 ) {
-			setsockopt( sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof( on ) );
-		}
-		if ( connect( sock, ptr->ai_addr, ptr->ai_addrlen ) < 0 ) {
-			// if ( bind( sock, ptr->ai_addr, ptr->ai_addrlen ) == -1 ) {
-			printf( "...socket Error, errno=%d\n", errno );
-			close( sock );
-			sock = -1;
-			continue;
-		} else {
-			printf( "... connecting successful!\n" );
-			break;
-		}
-	}
-
-	freeaddrinfo( res );
-	return sock;
-}
-
diff --git a/src/fuse/helper.h b/src/fuse/helper.h
index bbba44c..35cdc8a 100644
--- a/src/fuse/helper.h
+++ b/src/fuse/helper.h
@@ -4,6 +4,9 @@
 #include <netdb.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <string.h>
+
+#include "../types.h"
 
 
 typedef struct log_info {
@@ -21,4 +24,9 @@ bool sock_printable(struct sockaddr *addr, socklen_t addrLen, char *output, int
 
 int connect_to_server(char *server_adress, int port);
 
+static inline bool isSameAddressPort(const dnbd3_host_t * const a, const dnbd3_host_t * const b)
+{
+	return (a->type == b->type) && (a->port == b->port) && (0 == memcmp( a->addr, b->addr, (a->type == AF_INET ? 4 : 16) ));
+}
+
 #endif
diff --git a/src/fuse/log.h b/src/fuse/log.h
new file mode 100644
index 0000000..e429861
--- /dev/null
+++ b/src/fuse/log.h
@@ -0,0 +1,43 @@
+#ifndef LOG_H_
+#define LOG_H_
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+typedef unsigned int logmask_t;
+#define LOG_ERROR    ((logmask_t)1)  // Fatal error, server will terminate
+#define LOG_WARNING  ((logmask_t)2)  // Major issue, something is broken but keep running
+#define LOG_MINOR    ((logmask_t)4)  // Minor issue, more of a hickup than serious problem
+#define LOG_INFO     ((logmask_t)8)  // Informational message
+#define LOG_DEBUG1  ((logmask_t)16)  // Debug information, use this for non-spammy stuff
+#define LOG_DEBUG2  ((logmask_t)32)  // Use this for debug messages that will show up a lot
+
+//void log_setFileMask(logmask_t mask);
+
+//void log_setConsoleMask(logmask_t mask);
+
+/**
+ * Open or reopen the log file. If path is NULL and the
+ * function was called with a path before, the same path
+ * will be used again.
+ */
+//bool log_openLogFile(const char *path);
+
+/**
+ * Add a line to the log
+ */
+void logadd(const logmask_t mask, const char *text, ...)
+{
+	va_list args;
+	va_start( args, text );
+	vprintf( text, args );
+	va_end( args );
+}
+
+/**
+ * Return last size bytes of log.
+ */
+//bool log_fetch(char *buffer, int size);
+
+#endif /* LOG_H_ */
diff --git a/src/fuse/main.c b/src/fuse/main.c
index d6a4d98..7889023 100644
--- a/src/fuse/main.c
+++ b/src/fuse/main.c
@@ -58,7 +58,7 @@ static void dnbd3_connect()
 		if ( sock != -1 ) {
 			close( sock );
 		}
-		sock = connect_to_server( server_address, portno );
+		sock = -1; // connect_to_server( server_address, portno );
 
 		if ( sock == -1 ) {
 			debugf( "[ERROR] Connection Error!\n" );
diff --git a/src/server/altservers.c b/src/server/altservers.c
index 7a2aaf7..bbe33ba 100644
--- a/src/server/altservers.c
+++ b/src/server/altservers.c
@@ -1,7 +1,7 @@
 #include "altservers.h"
 #include "uplink.h"
 #include "locks.h"
-#include "sockhelper.h"
+#include "../shared/sockhelper.h"
 #include "log.h"
 #include "helper.h"
 #include "globals.h"
diff --git a/src/server/image.c b/src/server/image.c
index 6f2cb6a..8d2a77f 100644
--- a/src/server/image.c
+++ b/src/server/image.c
@@ -6,7 +6,7 @@
 #include "locks.h"
 #include "integrity.h"
 #include "../shared/protocol.h"
-#include "sockhelper.h"
+#include "../shared/sockhelper.h"
 #include "altservers.h"
 #include "server.h"
 #include "../shared/signal.h"
diff --git a/src/server/net.c b/src/server/net.c
index a7bdf86..4aab050 100644
--- a/src/server/net.c
+++ b/src/server/net.c
@@ -31,7 +31,7 @@
 #include <inttypes.h>
 #include <signal.h>
 
-#include "sockhelper.h"
+#include "../shared/sockhelper.h"
 #include "helper.h"
 #include "server.h"
 #include "image.h"
diff --git a/src/server/rpc.c b/src/server/rpc.c
index b709b94..6152d99 100644
--- a/src/server/rpc.c
+++ b/src/server/rpc.c
@@ -4,7 +4,7 @@
 #include "uplink.h"
 #include "log.h"
 #include "locks.h"
-#include "sockhelper.h"
+#include "../shared/sockhelper.h"
 #include "helper.h"
 #include "image.h"
 
diff --git a/src/server/server.c b/src/server/server.c
index 384ffa6..f47f208 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -33,7 +33,7 @@
 #include "../version.h"
 
 #include "locks.h"
-#include "sockhelper.h"
+#include "../shared/sockhelper.h"
 #include "server.h"
 #include "image.h"
 #include "uplink.h"
diff --git a/src/server/uplink.c b/src/server/uplink.c
index a205164..7910dc1 100644
--- a/src/server/uplink.c
+++ b/src/server/uplink.c
@@ -1,7 +1,7 @@
 #include "uplink.h"
 #include "locks.h"
 #include "log.h"
-#include "sockhelper.h"
+#include "../shared/sockhelper.h"
 #include "image.h"
 #include "helper.h"
 #include "altservers.h"
diff --git a/src/shared/signal.h b/src/shared/signal.h
index 0e2f85f..6fd2765 100644
--- a/src/shared/signal.h
+++ b/src/shared/signal.h
@@ -46,4 +46,3 @@ int signal_clear(int signalFd);
 void signal_close(int signalFd);
 
 #endif
-
diff --git a/src/server/sockhelper.c b/src/shared/sockhelper.c
index fb09ec2..0b7a1db 100644
--- a/src/server/sockhelper.c
+++ b/src/shared/sockhelper.c
@@ -1,5 +1,5 @@
 #include "sockhelper.h"
-#include "log.h"
+//#include "log.h"
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <arpa/inet.h> // inet_ntop
@@ -65,6 +65,79 @@ int sock_connect(const dnbd3_host_t * const addr, const int connect_ms, const in
 	return client_sock;
 }
 
+// TODO: Pretty much same as in server/*
+int sock_resolveToDnbd3Host(const char * const address, dnbd3_host_t * const dest, const int count)
+{
+	if ( count <= 0 )
+		return 0;
+	const int on = 1;
+	int sock = -1;
+	struct addrinfo hints, *res, *ptr;
+	char bufferAddr[100], bufferPort[6];
+	char *addr = bufferAddr;
+	const char *portStr = NULL;
+	int addCount = 0;
+
+	// See if we have a port
+	snprintf( bufferAddr, sizeof bufferAddr, "%s", address );
+	const char *c1, *c2;
+	c1 = strchr( addr, ':' );
+	if ( c1 != NULL ) {
+		c2 = strchr( c1 + 1, ':' );
+		if ( c2 == NULL ) {
+			*c1 = '\0';
+			portStr = c1 + 1;
+		} else if ( *addr == '[' ) {
+			// IPv6 - support [1:2::3]:123
+			do {
+				c1 = strchr( c2 + 1, ':' );
+				if ( c1 != NULL ) c2 = c1;
+			} while ( c1 != NULL );
+			if ( c2[-1] == ']' ) {
+				c2[-1] = '\0';
+				*c2 = '\0';
+				addr += 1;
+				portStr = c2 + 1;
+			}
+		}
+	}
+	if ( portStr == NULL ) {
+		portStr = bufferPort;
+		snprintf( bufferPort, sizeof bufferPort, "%d", (int)PORT );
+	}
+
+	// Set hints for local addresses.
+	memset( &hints, 0, sizeof( hints ) );
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	if ( getaddrinfo( addr, portStr, &hints, &res ) != 0 || res == NULL ) {
+		return 0;
+	}
+	for ( ptr = res; ptr != NULL && count > 0; ptr = ptr->ai_next ) {
+		// TODO: AF->DNBD3
+		if ( ptr->ai_addr->sa_family == AF_INET ) {
+			// Set host (IPv4)
+			struct sockaddr_in *addr4 = (struct sockaddr_in*)ptr->ai_addr;
+			dest[addCount].type = AF_INET;
+			dest[addCount].port = addr4->sin_port;
+			memcpy( dest[addCount].addr, &addr4->sin_addr, 4 );
+			addCount += 1;
+#ifdef WITH_IPV6
+		} else if ( ptr->ai_addr->sa_family == AF_INET6 ) {
+			// Set host (IPv6)
+			struct sockaddr_in6 *addr6 = (struct sockaddr_in6*)ptr->ai_addr;
+			dest[addCount].type = AF_INET6;
+			dest[addCount].port = addr6->sin6_port;
+			memcpy( dest[addCount].addr, &addr6->sin6_addr, 16 );
+			addCount += 1;
+#endif
+		}
+	}
+
+	freeaddrinfo( res );
+	return addCount;
+}
+
 void sock_setTimeout(const int sockfd, const int milliseconds)
 {
 	struct timeval tv;
diff --git a/src/server/sockhelper.h b/src/shared/sockhelper.h
index 3f4d485..3a4ab6c 100644
--- a/src/server/sockhelper.h
+++ b/src/shared/sockhelper.h
@@ -22,6 +22,13 @@ typedef struct _poll_list poll_list_t;
  */
 int sock_connect(const dnbd3_host_t * const addr, const int connect_ms, const int rw_ms);
 
+/**
+ * Resolve/parse given address and put the result(s) into passed dnbd3_host_t array,
+ * but only up to count entries.
+ * @return Number of items added to array
+ */
+int sock_resolveToDnbd3Host(const char * const address, dnbd3_host_t * const dest, const int count);
+
 void sock_setTimeout(const int sockfd, const int milliseconds);
 
 /**