CMakeLists.txt: added linker for GIO

handle.h: added option for LRO_NETWORK_WAIT and a helper function for handling netowork wait
handle.c: Added callback function required for GMainEventLoop and functionality for option
handle-py.c: Added the case for LRO_NETWORK_WAIT

Adds API support for waiting on network:
This waits for clients network interfaces till the specified time.
lr_handle_setopt(priv->repo_handle, error, LRO_NETWORK_WAIT, seconds)
This parses metalinkurl/baseurl and polls g_network_monitor_can_reach() in an event driven
manner with the help of GMainEventLoop.

librepo/CMakeLists.txt

@@ -52,6 +52,7 @@ TARGET_LINK_LIBRARIES(librepo
                         ${LIBCRYPTO_LIBRARIES}
                         ${GPGME_VANILLA_LIBRARIES}
                         ${GLIB2_LIBRARIES}
+                        ${GIO2_LIBRARIES}
                      )
 IF (WITH_ZCHUNK)
     TARGET_LINK_LIBRARIES(librepo ${ZCHUNKLIB_LIBRARIES})

librepo/handle.c

@@ -32,6 +32,8 @@
 #include <unistd.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <time.h>
+#include <gio/gio.h>
 
 
 #include "handle_internal.h"
@@ -264,6 +266,26 @@ lr_handle_remote_sources_changed(LrHandle *handle, LrChangedRemoteSource type)
     }
 }
 
+struct callback_data {
+   GMainLoop *loop; 
+   long input_seconds;
+   time_t begin;
+   GNetworkMonitor *monitor;
+   GSocketConnectable *connectable; 
+   GCancellable *cancellable;
+};
+
+gboolean timeout_callback(gpointer data)
+{ 
+  struct callback_data *dt = (struct callback_data*)data;
+   if(!g_network_monitor_can_reach(dt->monitor, dt->connectable, dt->cancellable, NULL) &&
+      time(NULL) - dt->begin <= dt->input_seconds){
+      return TRUE;
+   } 
+   g_main_loop_quit(dt->loop);
+   return FALSE;
+}
+
 gboolean
 lr_handle_setopt(LrHandle *handle,
                  GError **err,
@@ -812,6 +834,10 @@ lr_handle_setopt(LrHandle *handle,
         c_rc = curl_easy_setopt(c_h, CURLOPT_FILETIME, handle->preservetime);
         break;
 
+    case LRO_NETWORK_WAIT:
+        assert(lr_handle_network_wait(handle, err, va_arg(arg, long)));        
+        break;
+
     default:
         g_set_error(err, LR_HANDLE_ERROR, LRE_BADOPTARG,
                     "Unknown option");
@@ -841,7 +867,57 @@ lr_handle_setopt(LrHandle *handle,
     return ret;
 }
 
-static gboolean
+gboolean
+lr_handle_network_wait(LrHandle *handle, GError **err, guint seconds)
+{
+
+    assert(!err || *err == NULL);
+
+    if (!handle) {
+        g_set_error(err, LR_HANDLE_ERROR, LRE_BADFUNCARG,
+                    "No handle specified");
+        return FALSE;
+    }
+
+    GNetworkMonitor *monitor = g_network_monitor_get_default();
+    GCancellable *cancellable = g_cancellable_new ();
+
+    struct callback_data data_struct;
+    data_struct.input_seconds = seconds;
+    data_struct.begin = time(NULL);
+    data_struct.cancellable = cancellable;
+    data_struct.monitor = monitor;
+
+    gchar *baseurl;
+    if(handle->metalinkurl)
+      baseurl = handle->metalinkurl;
+    else if(handle->mirrorlisturl)
+      baseurl = handle->mirrorlisturl;
+    else if(handle->urls)
+      baseurl = handle->urls[0];
+    assert(baseurl);
+
+    GUri *uri = g_uri_parse(baseurl, G_URI_FLAGS_NONE, NULL);
+    if(uri == NULL){
+      return FALSE;
+    }
+    const gchar* host = g_uri_get_host(uri);
+    guint16 port = g_uri_get_port(uri);
+    GSocketConnectable *connectable =  g_network_address_new(host, port);
+    data_struct.connectable = connectable;
+    GMainLoop *loop;
+    loop = g_main_loop_new(NULL, FALSE);
+    data_struct.loop = loop;
+    g_timeout_add(200, timeout_callback, &data_struct); 
+    g_main_loop_run(loop);
+    g_main_loop_unref(loop);
+
+    //Check for handle->metalinkurl and handle->mirrorlisturl
+
+    return TRUE;
+}
+
+gboolean
 lr_handle_prepare_urls(LrHandle *handle, GError **err)
 {
     assert(!handle->urls_mirrors);

librepo/handle.h

@@ -430,6 +430,9 @@ typedef enum {
 
     LRO_SENTINEL,    /*!< Sentinel */
 
+    LRO_NETWORK_WAIT, /*!< (long)
+        This option waits time t until the baseurl is reachable.*/
+
 } LrHandleOption; /*!< Handle config options */
 
 /** Handle options for the ::lr_handle_getinfo function. */
@@ -560,6 +563,10 @@ lr_handle_getinfo(LrHandle *handle,
 gboolean
 lr_handle_perform(LrHandle *handle, LrResult *result, GError **err);
 
+
+gboolean
+lr_handle_network_wait(LrHandle *handle, GError **err, guint seconds);
+
 /** @} */
 
 G_END_DECLS

librepo/python/handle-py.c

@@ -470,6 +470,7 @@ py_setopt(_HandleObject *self, PyObject *args)
     case LRO_MAXDOWNLOADSPERMIRROR:
     case LRO_HTTPAUTHMETHODS:
     case LRO_PROXYAUTHMETHODS:
+    case LRO_NETWORK_WAIT:
     {
         long d;