Combine socket creation code

The client connection and the server listener sockets used largely similar
code. Combining them allows for simpler protocol code.

Cleaned up parts of the DCB listener creation and moved the parsing of the
network binding configuration to a higher level.

include/maxscale/utils.h

@@ -35,31 +35,39 @@ MXS_BEGIN_DECLS
  */
 #define MXS_PTR(a, b) (((uint8_t*)(a)) + (b))
 
+/** The type of the socket */
+enum mxs_socket_type
+{
+    MXS_SOCKET_LISTENER, /**< */
+    MXS_SOCKET_NETWORK,
+};
+
 bool utils_init(); /*< Call this first before using any other function */
 void utils_end();
 
-/**
- * Parse the bind configuration data.
- *
- * The configuration is passed as string in the `address|port` format.
- *
- * @param config        The bind address and port separated by a '|'
- * @param addr          The struct sockaddr_storage in which the data is written
- * @return              True on success, false on failure
- */
-bool parse_bindconfig(const char *config, struct sockaddr_storage *addr);
-
-
 /**
  * @brief Create a network socket and a socket configuration
  *
- * @param dest Pointer to a struct sockaddr_storage where the configuration is stored
+ * This helper function can be used to open both listener socket and network
+ * connection sockets. For listener sockets, the @c host and @c port parameters
+ * tell where the socket will bind to. For network sockets, the parameters tell
+ * where the connection is created.
+ *
+ * After calling this function, the only thing that needs to be done is to
+ * give @c addr and the return value of this function as the parameters to
+ * either bind() (for listeners) or connect() (for outbound network connections).
+ *
+ * @param type Type of the socket, either MXS_SOCKET_LISTENER for a listener
+ *             socket or MXS_SOCKET_NETWORK for a network connection socket
+ * @param addr Pointer to a struct sockaddr_storage where the socket
+ *             configuration is stored
  * @param host The target host for which the socket is created
  * @param port The target port on the host
  *
  * @return The opened socket or -1 on failure
  */
-int open_network_socket(struct sockaddr_storage *dest, char *host, uint16_t port);
+int open_network_socket(enum mxs_socket_type type, struct sockaddr_storage *addr,
+                        const char *host, uint16_t port);
 
 int setnonblocking(int fd);
 char  *gw_strend(register const char *s);