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=702455

configure.ac

@@ -1479,7 +1479,7 @@ else
 	    $CUPS_API_MAJOR -eq 1 -a $CUPS_API_MINOR -ge 6; then
       AC_DEFINE(HAVE_CUPS_API_1_6, 1,
                 [Define to 1 if CUPS 1.6 API is available])
-
+      have_cups_api_1_6=yes
     fi
 
     AC_SUBST(CUPS_API_MAJOR)

modules/printbackends/cups/gtkcupsutils.c

@@ -89,6 +89,20 @@ 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
@@ -659,6 +673,14 @@ 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

@@ -182,6 +182,9 @@ 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

@@ -82,6 +82,17 @@ gtk_printer_cups_init (GtkPrinterCups *printer)
   printer->get_remote_ppd_attempts = 0;
   printer->remote_cups_connection_test = NULL;
   printer->auth_info_required = NULL;
+#ifdef HAVE_CUPS_API_1_6
+  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
@@ -101,6 +112,12 @@ gtk_printer_cups_finalize (GObject *object)
   g_free (printer->default_cover_after);
   g_strfreev (printer->auth_info_required);
 
+#ifdef HAVE_CUPS_API_1_6
+  g_free (printer->avahi_name);
+  g_free (printer->avahi_type);
+  g_free (printer->avahi_domain);
+#endif
+
   if (printer->ppd_file)
     ppdClose (printer->ppd_file);
 
@@ -128,6 +145,7 @@ gtk_printer_cups_new (const char      *name,
 {
   GObject *result;
   gboolean accepts_pdf;
+  GtkPrinterCups *printer;
 
 #if (CUPS_VERSION_MAJOR == 1 && CUPS_VERSION_MINOR >= 2) || CUPS_VERSION_MAJOR > 1
   accepts_pdf = TRUE;
@@ -142,7 +160,16 @@ gtk_printer_cups_new (const char      *name,
 			 "accepts-pdf", accepts_pdf,
                          NULL);
 
-  return (GtkPrinterCups *) result;
+  printer = GTK_PRINTER_CUPS (result);
+
+  /*
+   * 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;
 }
 
 ppd_file_t *

modules/printbackends/cups/gtkprintercups.h

@@ -62,6 +62,17 @@ struct _GtkPrinterCups
   guint get_remote_ppd_poll;
   gint  get_remote_ppd_attempts;
   GtkCupsConnectionTest *remote_cups_connection_test;
+#ifdef HAVE_CUPS_API_1_6
+  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