check for multiple connected supported printers

securedrop_export/exceptions.py

@@ -22,6 +22,7 @@ class ExportStatus(Enum):
     USB_DISK_ERROR = 'USB_DISK_ERROR'
 
     # Printer preflight related errors
+    ERROR_MULTIPLE_PRINTERS_FOUND = 'ERROR_MULTIPLE_PRINTERS_FOUND'
     ERROR_PRINTER_NOT_FOUND = 'ERROR_PRINTER_NOT_FOUND'
     ERROR_PRINTER_NOT_SUPPORTED = 'ERROR_PRINTER_NOT_SUPPORTED'
     ERROR_PRINTER_DRIVER_UNAVAILABLE = 'ERROR_PRINTER_DRIVER_UNAVAILABLE'

securedrop_export/print/actions.py

@@ -50,6 +50,29 @@ def wait_for_print(self):
                 self.submission.exit_gracefully(ExportStatus.ERROR_PRINT.value)
         return True
 
+    def check_printer_setup(self) -> None:
+        try:
+            output = subprocess.check_output(["sudo", "lpinfo", "-v"])
+            printers = [x for x in output.decode('utf-8').split() if "usb://" in x]
+            if not printers:
+                logger.info('No usb printers connected')
+                self.exit_gracefully(ExportStatus.ERROR_PRINTER_NOT_FOUND.value)
+
+            supported_printers = [x for x in printers if x in ("Brother", "LaserJet")]
+            if not supported_printers:
+                logger.info('{} are unsupported printers'.format(printers))
+                self.exit_gracefully(ExportStatus.ERROR_PRINTER_NOT_SUPPORTED.value)
+
+            if len(supported_printers) > 1:
+                logger.info('Too many usb printers connected')
+                self.exit_gracefully(ExportStatus.ERROR_MULTIPLE_PRINTERS_FOUND.value)
+
+            printer_uri = printers[0]
+            printer_ppd = self._install_printer_ppd(printer_uri)
+            self._setup_printer(printer_uri, printer_ppd)
+        except subprocess.CalledProcessError:
+            self.submission.exit_gracefully(ExportStatus.ERROR_GENERIC.value)
+
     def get_printer_uri(self):
         # Get the URI via lpinfo and only accept URIs of supported printers
         printer_uri = ""
@@ -204,6 +227,7 @@ def __init__(self, *args, **kwargs):
 
     def run(self):
         logger.info('Export archive is printer')
+        self.check_printer_setup()
         # prints all documents in the archive
         logger.info('Searching for printer')
         printer_uri = self.get_printer_uri()
@@ -220,6 +244,8 @@ def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
     def run(self):
+        logger.info('Export archive is printer-test')
+        self.check_printer_setup()
         # Prints a test page to ensure the printer is functional
         printer_uri = self.get_printer_uri()
         printer_ppd = self.install_printer_ppd(printer_uri)