Check file validity.

4 files changed, 69 insertions, 11 deletions

diff --git a/xandikos/icalendar.py b/xandikos/icalendar.py
index 77ddbed..aa631dc 100644
--- a/xandikos/icalendar.py
+++ b/xandikos/icalendar.py
@@ -24,7 +24,7 @@
 import logging
 
 from icalendar.cal import Calendar, component_factory
-from xandikos.store import File
+from xandikos.store import File, InvalidFileContents
 
 
 def calendar_component_delta(old_cal, new_cal):
@@ -139,6 +139,13 @@ class ICalendarFile(File):
         super(ICalendarFile, self).__init__(content, content_type)
         self._calendar = None
 
+    def validate(self):
+        """Verify that file contents are valid."""
+        try:
+            self.calendar
+        except ValueError:
+            raise InvalidFileContents(self.content_type, self.content)
+
     @property
     def calendar(self):
         if self._calendar is None:
diff --git a/xandikos/store.py b/xandikos/store.py
index e6245b3..8e35c80 100644
--- a/xandikos/store.py
+++ b/xandikos/store.py
@@ -58,6 +58,13 @@ class File(object):
         self.content = content
         self.content_type = content_type
 
+    def validate(self):
+        """Verify that file contents are valid.
+
+        :raise InvalidFileContents: Raised if a file is not valid
+        """
+        pass
+
     def describe(self, name):
         """Describe the contents of this file.
 
@@ -144,6 +151,14 @@ class NotStoreError(Exception):
         self.path = path
 
 
+class InvalidFileContents(Exception):
+    """Invalid file contents."""
+
+    def __init__(self, content_type, data):
+        self.content_type = content_type
+        self.data = data
+
+
 class Store(object):
     """A object store."""
 
@@ -344,7 +359,7 @@ class GitStore(Store):
         fi = open_by_content_type(data, content_type, self.extra_file_handlers)
         if name is None:
             name = str(uuid.uuid4()) + mimetypes.guess_extension(content_type)
-        # TODO(jelmer): Verify that 'data' actually represents a valid object
+        fi.validate()
         try:
             uid = fi.get_uid()
         except (KeyError, NotImplementedError):
diff --git a/xandikos/web.py b/xandikos/web.py
index 0138417..991fb08 100644
--- a/xandikos/web.py
+++ b/xandikos/web.py
@@ -36,6 +36,7 @@ from xandikos.icalendar import ICalendarFile
 from xandikos.store import (
     TreeGitStore,
     GitStore,
+    InvalidFileContents,
     NoSuchItem,
     NotStoreError,
     STORE_TYPE_ADDRESSBOOK,
@@ -102,9 +103,15 @@ class ObjectResource(webdav.Resource):
         return self.file.content
 
     def set_body(self, data, replace_etag=None):
-        (name, etag) = self.store.import_one(
-            self.name, self.content_type, data,
-            replace_etag=extract_strong_etag(replace_etag))
+        try:
+            (name, etag) = self.store.import_one(
+                self.name, self.content_type, data,
+                replace_etag=extract_strong_etag(replace_etag))
+        except InvalidFileContents:
+            # TODO(jelmer): Not every invalid file is a calendar file..
+            raise webdav.PreconditionFailure(
+                '{%s}valid-calendar-data' % caldav.NAMESPACE,
+                'Not a valid calendar file.')
         return create_strong_etag(etag)
 
     def get_content_language(self):
@@ -198,8 +205,14 @@ class StoreBasedCollection(object):
             shutil.rmtree(os.path.join(self.store.path, name))
 
     def create_member(self, name, contents, content_type):
-        (name, etag) = self.store.import_one(name, content_type,
-            contents)
+        try:
+            (name, etag) = self.store.import_one(name, content_type,
+                contents)
+        except InvalidFileContents:
+            # TODO(jelmer): Not every invalid file is a calendar file..
+            raise webdav.PreconditionFailure(
+                '{%s}valid-calendar-data' % caldav.NAMESPACE,
+                'Not a valid calendar file.')
         return (name, create_strong_etag(etag))
 
     def iter_differences_since(self, old_token, new_token):
diff --git a/xandikos/webdav.py b/xandikos/webdav.py
index 4846753..aa126d7 100644
--- a/xandikos/webdav.py
+++ b/xandikos/webdav.py
@@ -52,6 +52,14 @@ class BadRequestError(Exception):
         self.message = message
 
 
+class PreconditionFailure(Exception):
+    """A precondition failed."""
+
+    def __init__(self, precondition, description):
+        self.precondition = precondition
+        self.description = description
+
+
 def etag_matches(condition, actual_etag):
     """Check if an etag matches an If-Matches condition.
 
@@ -1117,7 +1125,12 @@ class WebDAVApp(object):
             start_response('405 Method Not Allowed', [])
             return []
         content_type = environ['CONTENT_TYPE'].split(';')[0]
-        (name, etag) = r.create_member(None, new_contents, content_type)
+        try:
+            (name, etag) = r.create_member(None, new_contents, content_type)
+        except PreconditionFailure as e:
+            return _send_simple_dav_error(
+                environ, start_response, '412 Precondition Failed',
+                error=ET.Element(e.precondition))
         href = environ['SCRIPT_NAME'] + urllib.parse.urljoin(path+'/', name)
         start_response('200 OK', [
             ('Location', href)
@@ -1137,7 +1150,12 @@ class WebDAVApp(object):
             start_response('412 Precondition Failed', [])
             return []
         if r is not None:
-            new_etag = r.set_body(new_contents, current_etag)
+            try:
+                new_etag = r.set_body(new_contents, current_etag)
+            except PreconditionFailure as e:
+                return _send_simple_dav_error(
+                    environ, start_response, '412 Precondition Failed',
+                    error=ET.Element(e.precondition))
             start_response('204 No Content', [
                 ('ETag', new_etag)])
             return []
@@ -1145,8 +1163,13 @@ class WebDAVApp(object):
         container_path, name = posixpath.split(path)
         r = self.backend.get_resource(container_path)
         if r is not None:
-            (new_name, new_etag) = r.create_member(
-                name, new_contents, content_type)
+            try:
+                (new_name, new_etag) = r.create_member(
+                    name, new_contents, content_type)
+            except PreconditionFailure as e:
+                return _send_simple_dav_error(
+                    environ, start_response, '412 Precondition Failed',
+                    error=ET.Element(e.precondition))
             start_response('201 Created', [
                 ('ETag', new_etag)])
             return []