printing: List Avahi printers

Show printers advertised by avahi on local network. CUPS
backend now looks for _ipps._tcp and _ipp._tcp services
offered by avahi. If it finds such a service (printer)
it requests its attributes through IPP_GET_PRINTER_ATTRIBUTES
ipp request and adds it to the list of printers. Such printer
behaves like a remote printer then.
If an avahi printer is a default printer then it is considered
default by the backend only if there is no local or remote
default printer.
This functionality is enabled when building Gtk+ with CUPS 1.6
or later because it replaces browsing protocol removed in CUPS 1.6.

https://bugzilla.gnome.org/show_bug.cgi?id=688956

modules/printbackends/cups/Makefile.am

@@ -12,6 +12,7 @@ AM_CPPFLAGS = \
 	-I$(top_builddir)/gdk				\
 	$(CUPS_CFLAGS)					\
 	$(COLORD_CFLAGS)				\
+	$(AVAHI_CFLAGS)					\
 	-DGTK_COMPILATION				\
 	-DGTK_PRINT_BACKEND_ENABLE_UNSUPPORTED		\
 	$(GTK_DEP_CFLAGS)				\
@@ -37,6 +38,6 @@ noinst_HEADERS =			\
 	gtkcupsutils.h
 
 libprintbackend_cups_la_LDFLAGS =  -avoid-version -module $(no_undefined)
-libprintbackend_cups_la_LIBADD = $(LDADDS) $(CUPS_LIBS)
+libprintbackend_cups_la_LIBADD = $(LDADDS) $(CUPS_LIBS) $(AVAHI_LIBS)
 
 -include $(top_srcdir)/git.mk

modules/printbackends/cups/gtkcupsutils.c

@@ -87,6 +87,20 @@ static GtkCupsRequestStateFunc get_states[] = {
 #define ippSetState(ipp_request, ipp_state) ipp_request->state = ipp_state
 #define ippGetString(attr, index, foo) attr->values[index].string.text
 #define ippGetCount(attr) attr->num_values
+
+int
+ippSetVersion (ipp_t *ipp,
+               int    major,
+               int    minor)
+{
+  if (!ipp || major < 0 || minor < 0)
+    return 0;
+
+  ipp->request.any.version[0] = major;
+  ipp->request.any.version[1] = minor;
+
+  return 1;
+}
 #endif
 
 static void
@@ -656,6 +670,13 @@ gtk_cups_request_encode_option (GtkCupsRequest *request,
     }
 }
 				
+void
+gtk_cups_request_set_ipp_version (GtkCupsRequest     *request,
+				  gint                major,
+				  gint                minor)
+{
+  ippSetVersion (request->ipp_request, major, minor);
+}
 
 static void
 _connect (GtkCupsRequest *request)

modules/printbackends/cups/gtkcupsutils.h

@@ -178,6 +178,9 @@ gboolean                gtk_cups_request_is_done           (GtkCupsRequest     *
 void                    gtk_cups_request_encode_option     (GtkCupsRequest     *request,
 						            const gchar        *option,
 							    const gchar        *value);
+void                    gtk_cups_request_set_ipp_version   (GtkCupsRequest     *request,
+							    gint                major,
+							    gint                minor);
 gboolean                gtk_cups_result_is_error           (GtkCupsResult      *result);
 ipp_t                 * gtk_cups_result_get_response       (GtkCupsResult      *result);
 GtkCupsErrorType        gtk_cups_result_get_error_type     (GtkCupsResult      *result);

modules/printbackends/cups/gtkprintercups.c

@@ -114,6 +114,17 @@ gtk_printer_cups_init (GtkPrinterCups *printer)
   printer->remote_cups_connection_test = NULL;
   printer->auth_info_required = NULL;
   printer->default_number_up = 1;
+#ifdef HAVE_AVAHI_BROWSING
+  printer->avahi_browsed = FALSE;
+  printer->avahi_name = NULL;
+  printer->avahi_type = NULL;
+  printer->avahi_domain = NULL;
+#endif
+  printer->ipp_version_major = 1;
+  printer->ipp_version_minor = 1;
+  printer->supports_copies = FALSE;
+  printer->supports_collate = FALSE;
+  printer->supports_number_up = FALSE;
 }
 
 static void
@@ -134,8 +145,11 @@ gtk_printer_cups_finalize (GObject *object)
   g_strfreev (printer->auth_info_required);
 
 #ifdef HAVE_COLORD
-  g_cancellable_cancel (printer->colord_cancellable);
-  g_object_unref (printer->colord_cancellable);
+  if (printer->colord_cancellable)
+    {
+      g_cancellable_cancel (printer->colord_cancellable);
+      g_object_unref (printer->colord_cancellable);
+    }
   g_free (printer->colord_title);
   g_free (printer->colord_qualifier);
   if (printer->colord_client)
@@ -146,6 +160,12 @@ gtk_printer_cups_finalize (GObject *object)
     g_object_unref (printer->colord_profile);
 #endif
 
+#ifdef HAVE_AVAHI_BROWSING
+  g_free (printer->avahi_name);
+  g_free (printer->avahi_type);
+  g_free (printer->avahi_domain);
+#endif
+
   if (printer->ppd_file)
     ppdClose (printer->ppd_file);
 
@@ -512,7 +532,8 @@ colord_printer_details_aquired_cb (GtkPrinterCups *printer,
                                    gpointer user_data)
 {
   /* refresh the device */
-  colord_update_device (printer);
+  if (printer->colord_client)
+    colord_update_device (printer);
 }
 #endif
 
@@ -565,6 +586,14 @@ gtk_printer_cups_new (const char      *name,
                       G_CALLBACK (colord_printer_details_aquired_cb),
                       printer);
 #endif
+
+  /*
+   * IPP version 1.1 has to be supported
+   * by all implementations according to rfc 2911
+   */
+  printer->ipp_version_major = 1;
+  printer->ipp_version_minor = 1;
+
   return printer;
 }
 

modules/printbackends/cups/gtkprintercups.h

@@ -75,6 +75,17 @@ struct _GtkPrinterCups
   gchar        *colord_title;
   gchar        *colord_qualifier;
 #endif
+#ifdef HAVE_AVAHI_BROWSING
+  gboolean  avahi_browsed;
+  gchar    *avahi_name;
+  gchar    *avahi_type;
+  gchar    *avahi_domain;
+#endif
+  guchar ipp_version_major;
+  guchar ipp_version_minor;
+  gboolean supports_copies;
+  gboolean supports_collate;
+  gboolean supports_number_up;
 };
 
 struct _GtkPrinterCupsClass