From 66eb2316652f0d770ce714f5741a1eaa0ae0e590 Mon Sep 17 00:00:00 2001
From: deeplow <francisco@freedom.press>
Date: Fri, 17 Jan 2025 11:35:25 +0000
Subject: [PATCH] Handle printer discovery failure through exceptions

Incapsulate printer search and possible failure in the respective
printer search methods.
---
 export/securedrop_export/print/exceptions.py |  9 ++++++
 export/securedrop_export/print/service.py    | 32 ++++++++++++--------
 2 files changed, 28 insertions(+), 13 deletions(-)
 create mode 100644 export/securedrop_export/print/exceptions.py

diff --git a/export/securedrop_export/print/exceptions.py b/export/securedrop_export/print/exceptions.py
new file mode 100644
index 000000000..da9e93843
--- /dev/null
+++ b/export/securedrop_export/print/exceptions.py
@@ -0,0 +1,9 @@
+from securedrop_export.exceptions import ExportException
+
+from .status import Status
+
+
+class PrinterNotFoundException(ExportException):
+    def __init__(self, sderror=None):
+        super().__init__()
+        self.sdstatus = Status.ERROR_PRINTER_NOT_FOUND
diff --git a/export/securedrop_export/print/service.py b/export/securedrop_export/print/service.py
index 35e55cad7..b434fdf4a 100644
--- a/export/securedrop_export/print/service.py
+++ b/export/securedrop_export/print/service.py
@@ -6,6 +6,7 @@
 from securedrop_export.directory import safe_mkdir
 from securedrop_export.exceptions import ExportException
 
+from .exceptions import PrinterNotFoundException
 from .print_dialog import open_print_dialog
 from .status import Status
 
@@ -120,9 +121,9 @@ def _check_printer_setup(self) -> None:
         legacy_printers = False
         logger.info("Searching for printer")
 
-        printers = self._get_printers_ipp()
-        if not printers:
-            # look for legacy printers after no IPP ones are detected
+        try:
+            printers = self._get_printers_ipp()
+        except PrinterNotFoundException:
             printers = self._get_printers_legacy()
             legacy_printers = True
 
@@ -147,13 +148,18 @@ def _get_printers_legacy(self) -> list[str]:
             raise ExportException(sdstatus=Status.ERROR_UNKNOWN)
 
         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)
         ]
+        unsupported_printers = [p for p in discovered_printers if p not in supported_printers]
+
         if not supported_printers:
-            logger.info(f"{discovered_printers} are unsupported printers")
-            raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_SUPPORTED)
+            if unsupported_printers:
+                logger.info(f"{', '.join(unsupported_printers)} are unsupported printers")
+                raise ExportException(sdstatus=Status.ERROR_PRINTER_NOT_SUPPORTED)
+            else:
+                logger.info("No legacy (PDP) printers were found")
+                raise PrinterNotFoundException()
 
         return supported_printers
 
@@ -163,14 +169,14 @@ def _get_printers_ipp(self) -> list[str]:
             discovered_printers = subprocess.check_output(
                 ["ippfind"], universal_newlines=True
             ).split()
-        except subprocess.CalledProcessError as e:
-            logger.error(e)
-            raise ExportException(sdstatus=Status.ERROR_UNKNOWN)
-
-        if discovered_printers:
             logger.debug(f"Found IPP printers: {', '.join(discovered_printers)}")
-        else:
-            logger.debug("No IPP were found")
+        except subprocess.CalledProcessError as ex:
+            if ex.returncode == 1:  # Did not find any match
+                logger.debug("No IPP printers were found")
+                raise PrinterNotFoundException()
+            else:
+                logger.error("'ippfind' command failed")
+                raise ExportException(sdstatus=Status.ERROR_PRINTER_URI)
 
         return discovered_printers