From 748bcc328fc7eb21715a992d4f52e1de61431bfb Mon Sep 17 00:00:00 2001
From: Paul Selkirk <paul@painless-security.com>
Date: Wed, 27 Dec 2023 12:56:38 -0500
Subject: [PATCH] fix: Wrap weasyprint to catch exceptions (#6728)

* fix: Wrap weasyprint to catch exceptions (#6324)

* test: Restore socket function after test

* test: Use mock instead of monkeying with sockets

* refactor: Log the error

* fix: Don't catch non-Exception interruptions

---------

Co-authored-by: Robert Sparks <rjsparks@nostrum.com>
---
 ietf/doc/models.py                        |  3 +++
 ietf/doc/tests.py                         |  8 ++++++++
 ietf/doc/views_doc.py                     |  6 ++++--
 ietf/templates/doc/weasyprint_failed.html | 17 +++++++++++++++++
 4 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 ietf/templates/doc/weasyprint_failed.html

diff --git a/ietf/doc/models.py b/ietf/doc/models.py
index 434096929a..e53717cb7d 100644
--- a/ietf/doc/models.py
+++ b/ietf/doc/models.py
@@ -634,6 +634,9 @@ def pdfized(self):
                 )
             except AssertionError:
                 pdf = None
+            except Exception as e:
+                log.log('weasyprint failed:'+str(e))
+                raise
             if pdf:
                 cache.set(cache_key, pdf, settings.PDFIZER_CACHE_TIME)
         return pdf
diff --git a/ietf/doc/tests.py b/ietf/doc/tests.py
index 71ec23906c..0b5a651060 100644
--- a/ietf/doc/tests.py
+++ b/ietf/doc/tests.py
@@ -31,6 +31,8 @@
 
 from tastypie.test import ResourceTestCaseMixin
 
+from weasyprint.urls import URLFetchingError
+
 import debug                            # pyflakes:ignore
 
 from ietf.doc.models import ( Document, DocRelationshipName, RelatedDocument, State,
@@ -2867,6 +2869,12 @@ def test_pdfized(self):
                 self.should_succeed(dict(name=draft.name,rev=f'{r:02d}',ext=ext))
         self.should_404(dict(name=draft.name,rev='02'))
 
+        with mock.patch('ietf.doc.models.DocumentInfo.pdfized', side_effect=URLFetchingError):
+            url = urlreverse(self.view, kwargs=dict(name=rfc.name))
+            r = self.client.get(url)
+            self.assertEqual(r.status_code, 200)
+            self.assertContains(r, "Error while rendering PDF")
+
 class NotifyValidationTests(TestCase):
     def test_notify_validation(self):
         valid_values = [
diff --git a/ietf/doc/views_doc.py b/ietf/doc/views_doc.py
index e0bf328e89..293d32daff 100644
--- a/ietf/doc/views_doc.py
+++ b/ietf/doc/views_doc.py
@@ -51,7 +51,6 @@
 from django import forms
 from django.contrib.staticfiles import finders
 
-
 import debug                            # pyflakes:ignore
 
 from ietf.doc.models import ( Document, DocHistory, DocEvent, BallotDocEvent, BallotType,
@@ -1064,7 +1063,10 @@ def document_pdfized(request, name, rev=None, ext=None):
     if not os.path.exists(doc.get_file_name()):
         raise Http404("File not found: %s" % doc.get_file_name())
 
-    pdf = doc.pdfized()
+    try:
+        pdf = doc.pdfized()
+    except Exception:
+        return render(request, "doc/weasyprint_failed.html")
     if pdf:
         return HttpResponse(pdf,content_type='application/pdf')
     else:
diff --git a/ietf/templates/doc/weasyprint_failed.html b/ietf/templates/doc/weasyprint_failed.html
new file mode 100644
index 0000000000..985fe12fe1
--- /dev/null
+++ b/ietf/templates/doc/weasyprint_failed.html
@@ -0,0 +1,17 @@
+{# Copyright The IETF Trust 2023, All Rights Reserved #}
+{% extends "base.html" %}
+{% load origin %}
+{% block title %}Error while rendering PDF{% endblock %}
+{% block content %}
+    {% origin %}
+    <h1>Error while rendering PDF</h1>
+    <p>
+        An error was encountered while trying to render your document as PDF.
+	In case this was a temporary error, you may want to try again in a
+        little while.
+    </p>
+    <p>
+        A failure report with details about what happened has been sent to the
+        server administrators.
+    </p>
+{% endblock %}
\ No newline at end of file