Initial support for IPP / driverless printing

debian/control

@@ -14,7 +14,8 @@ Description: securedrop client for qubes workstation
 
 Package: securedrop-export
 Architecture: all
-Depends: ${misc:Depends}, python3, udisks2, cups, printer-driver-brlaser, printer-driver-hpcups, system-config-printer, xpp, libcups2, gnome-disk-utility, libreoffice,
+Depends: ${misc:Depends}, python3, udisks2, cups, cups-ipp-utils, printer-driver-brlaser, printer-driver-hpcups,
+ avahi-daemon, system-config-printer, xpp, libcups2, gnome-disk-utility, libreoffice,
  desktop-file-utils, shared-mime-info, libfile-mimeinfo-perl
 Description: Submission export scripts for SecureDrop Workstation
  This package provides scripts used by the SecureDrop Qubes Workstation to

debian/securedrop-export.install

@@ -2,3 +2,4 @@ export/files/application-x-sd-export.xml usr/share/mime/packages
 export/files/send-to-usb.desktop usr/share/applications
 export/files/sd-logo.png usr/share/securedrop/icons
 export/files/tcrypt.conf etc/udisks2
+export/files/60-securedrop-export.preset usr/lib/systemd/system-preset

export/files/60-securedrop-export.preset

@@ -0,0 +1,4 @@
+# avahi-daemon so that driverless printers are detected when
+# plugged in via USB, overriding 75-qubes-vm.preset
+
+enable avahi-daemon.service

export/securedrop_export/print/service.py

@@ -143,32 +143,59 @@ def _check_printer_setup(self) -> None:
         Check printer setup.
         Raise ExportException if supported setup is not found.
         """
+        legacy_printers=False
         try:
             logger.info("Searching for printer")
-            output = subprocess.check_output(["sudo", "lpinfo", "-v"])
-            printers = [x for x in output.decode("utf-8").split() if "usb://" in x]
+
+            printers = self._get_printers_ipp()
             if not printers:
-                logger.info("No usb printers connected")
-                raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_FOUND)
+                # look for legacy printers after no IPP ones are detected
+                printers = self._get_printers_legacy()
+                legacy_printers=True
 
-            supported_printers = [
-                p for p in printers if any(sub in p for sub in self.SUPPORTED_PRINTERS)
-            ]
-            if not supported_printers:
-                logger.info(f"{printers} are unsupported printers")
-                raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_SUPPORTED)
+            if not printers:
+                logger.info("No supported printers connected")
+                raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_FOUND)
 
-            if len(supported_printers) > 1:
-                logger.info("Too many usb printers connected")
+            if len(printers) > 1:
+                logger.info("Too many printers connected")
                 raise ExportException(sdstatus=Status.ERROR_MULTIPLE_PRINTERS_FOUND)
 
             printer_uri = printers[0]
-            printer_ppd = self._install_printer_ppd(printer_uri)
-            self._setup_printer(printer_uri, printer_ppd)
+            if legacy_printers:  # IPP printers are auto-detected by the print dialog
+                self._setup_printer(printer_uri)
         except subprocess.CalledProcessError as e:
             logger.error(e)
             raise ExportException(sdstatus=Status.ERROR_UNKNOWN)
 
+    def _get_printers_legacy(self) -> list[str]:
+        logger.info("Searching for legacy printers")
+        output = subprocess.check_output(["sudo", "lpinfo", "-v"])
+        discovered_printers = [x for x in output.decode("utf-8").split() if "usb://" in x]
+
+        supported_printers = [
+            p for p in discovered_printers if any(sub in p for sub in self.SUPPORTED_PRINTERS)
+        ]
+        if not supported_printers:
+            logger.info(f"{discovered_printers} are unsupported printers")
+            raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_SUPPORTED)
+
+        return supported_printers
+
+    def _get_printers_ipp(self) -> list[str]:
+        logger.info("Searching for IPP printers (driverless)")
+        discovered_printers = subprocess.check_output(
+            ["ippfind"],
+            universal_newlines=True
+        ).split()
+
+        if discovered_printers:
+            logger.debug(f"Found IPP printers: {', '.join(discovered_printers)}")
+        else:
+            logger.debug(f"No IPP were found")
+
+        return discovered_printers
+
     def _get_printer_uri(self) -> str:
         """
         Get the URI via lpinfo. Only accept URIs of supported printers.
@@ -202,6 +229,9 @@ def _get_printer_uri(self) -> str:
         return printer_uri
 
     def _install_printer_ppd(self, uri):
+        """
+        Discovery and installation of PPD driver (for legacy printers)
+        """
         if not any(x in uri for x in self.SUPPORTED_PRINTERS):
             logger.error(f"Cannot install printer ppd for unsupported printer: {uri}")
             raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_SUPPORTED)