Compatibility workaround: Accept XML content from calendar server even if it's marked up with content-type text/plain

caldav/davclient.py

@@ -73,64 +73,60 @@ def __init__(
         if davclient:
             self.huge_tree = davclient.huge_tree
 
-        ## TODO: this if/else/elif could possibly be refactored, or we should
-        ## consider to do streaming into the xmltree library as originally
-        ## intended.  It only makes sense for really huge payloads though.
-        if self.headers.get("Content-Type", "").startswith(
-            "text/xml"
-        ) or self.headers.get("Content-Type", "").startswith("application/xml"):
-            try:
-                content_length = int(self.headers["Content-Length"])
-            except:
-                content_length = -1
-            if content_length == 0 or not self._raw:
-                self._raw = ""
-                self.tree = None
-                log.debug("No content delivered")
-            else:
-                ## With response.raw we could be streaming the content, but it does not work because
-                ## the stream often is compressed.  We could add uncompression on the fly, but not
-                ## considered worth the effort as for now.
-                # self.tree = etree.parse(response.raw, parser=etree.XMLParser(remove_blank_text=True))
-                try:
-                    self.tree = etree.XML(
-                        self._raw,
-                        parser=etree.XMLParser(
-                            remove_blank_text=True, huge_tree=self.huge_tree
-                        ),
-                    )
-                except:
-                    logging.critical(
-                        "Expected some valid XML from the server, but got this: \n"
-                        + str(self._raw),
-                        exc_info=True,
-                    )
-                    raise
-                if log.level <= logging.DEBUG:
-                    log.debug(etree.tostring(self.tree, pretty_print=True))
-        elif self.headers.get("Content-Type", "").startswith(
-            "text/calendar"
-        ) or self.headers.get("Content-Type", "").startswith("text/plain"):
-            ## text/plain is typically for errors, we shouldn't see it on 200/207 responses.
-            ## TODO: may want to log an error if it's text/plain and 200/207.
-            ## Logic here was moved when refactoring
-            pass
+        content_type = self.headers.get("Content-Type", "")
+        xml = ["text/xml", "application/xml"]
+        no_xml = ["text/plain", "text/calendar"]
+        expect_xml = any((content_type.startswith(x) for x in xml))
+        expect_no_xml = any((content_type.startswith(x) for x in no_xml))
+        try:
+            content_length = int(self.headers["Content-Length"])
+        except:
+            content_length = -1
+        if content_length == 0 or not self._raw:
+            self._raw = ""
+            self.tree = None
+            log.debug("No content delivered")
         else:
-            ## Probably no content type given (iCloud).  Some servers
-            ## give text/html as the default when no content is
-            ## delivered or on errors (ref
-            ## https://github.com/python-caldav/caldav/issues/142).
-            ## TODO: maybe just remove all of the code above in this if/else and let all
-            ## data be parsed through this code.
+            ## For really huge objects we should pass the object as a stream to the
+            ## XML parser, like this:
+            # self.tree = etree.parse(response.raw, parser=etree.XMLParser(remove_blank_text=True))
+            ## However, we would also need to decompress on the fly.  I won't bother now.
             try:
+                ## https://github.com/python-caldav/caldav/issues/142
+                ## We cannot trust the content=type (iCloud, OX and others).
+                ## We'll try to parse the content as XML no matter
+                ## the content type given.
                 self.tree = etree.XML(
                     self._raw,
                     parser=etree.XMLParser(
                         remove_blank_text=True, huge_tree=self.huge_tree
                     ),
                 )
             except:
-                pass
+                ## Content wasn't XML.  What does the content-type say?
+                ## expect_no_xml means text/plain or text/calendar
+                ## expect_no_xml -> ok, pass on, with debug logging
+                ## expect_xml means text/xml or application/xml
+                ## expect_xml -> raise an error
+                ## anything else (text/plain, text/html, ''),
+                ## log an error and continue
+                if not expect_no_xml or log.level <= logging.DEBUG:
+                    if not expect_no_xml:
+                        _log = logging.critical
+                    else:
+                        _log = logging.debug
+                        ## The statement below may not be true.
+                        ## We may be expecting something else
+                    _log(
+                        "Expected some valid XML from the server, but got this: \n"
+                        + str(self._raw),
+                        exc_info=True,
+                    )
+                if expect_xml:
+                    raise
+            else:
+                if log.level <= logging.DEBUG:
+                    log.debug(etree.tostring(self.tree, pretty_print=True))
 
         ## this if will always be true as for now, see other comments on streaming.
         if hasattr(self, "_raw"):