Fix #355 url escaping

src/icalendar/parser.py

@@ -259,25 +259,6 @@ def from_ical(cls, st, strict=False):
                                  % (param, exc))
         return result
 
-
-def escape_string(val):
-    # '%{:02X}'.format(i)
-    return val.replace(r'\,', '%2C').replace(r'\:', '%3A')\
-              .replace(r'\;', '%3B').replace(r'\\', '%5C')
-
-
-def unescape_string(val):
-    return val.replace('%2C', ',').replace('%3A', ':')\
-              .replace('%3B', ';').replace('%5C', '\\')
-
-
-def unescape_list_or_string(val):
-    if isinstance(val, list):
-        return [unescape_string(s) for s in val]
-    else:
-        return unescape_string(val)
-
-
 #########################################
 # parsing and generation of content lines
 
@@ -315,34 +296,68 @@ def from_parts(cls, name, params, values, sorted=True):
         return cls(f'{name}:{values}')
 
     def parts(self):
-        """Split the content line up into (name, parameters, values) parts.
+        """
+        Split the content line up into (name, parameters, values) parts.
+
+        Example with parameter:
+        DESCRIPTION;ALTREP="cid:[email protected]":The Fall'98 Wild
+
+        Example without parameters:
+        DESCRIPTION:The Fall'98 Wild
+
+        https://icalendar.org/iCalendar-RFC-5545/3-2-property-parameters.html
         """
         try:
-            st = escape_string(self)
+            st = self
             name_split = None
             value_split = None
             in_quotes = False
+            # Any character can be escaped using a backslash, e.g.: "test\:test"
+            quote_character = False
             for i, ch in enumerate(st):
-                if not in_quotes:
-                    if ch in ':;' and not name_split:
-                        name_split = i
-                    if ch == ':' and not value_split:
-                        value_split = i
+                # We can also quote using quotation marks. This ignores any output, until another quote appears.
                 if ch == '"':
                     in_quotes = not in_quotes
-            name = unescape_string(st[:name_split])
+                    continue
+
+                # Ignore input, as we are currently in quotation mark quotes
+                if in_quotes:
+                    continue
+
+                # Skip quoted character
+                if quote_character:
+                    quote_character = False
+                    continue
+
+                # The next character should be ignored
+                if ch == '\\':
+                    quote_character = True
+                    continue
+
+                # The name ends either after the parameter or value delimiter
+                if ch in ':;' and not name_split:
+                    name_split = i
+
+                # The value starts after the value delimiter
+                if ch == ':' and not value_split:
+                    value_split = i
+
+            # Get name
+            name = st[:name_split]
             if not name:
                 raise ValueError('Key name is required')
             validate_token(name)
+
+            # Check if parameters are empty
             if not name_split or name_split + 1 == value_split:
                 raise ValueError('Invalid content line')
+
+            # Get parameters (text between ; and :)
             params = Parameters.from_ical(st[name_split + 1: value_split],
-                                          strict=self.strict)
-            params = Parameters(
-                (unescape_string(key), unescape_list_or_string(value))
-                for key, value in iter(params.items())
-            )
-            values = unescape_string(st[value_split + 1:])
+                                        strict=self.strict)
+
+            # Get the value after the :
+            values = st[value_split + 1:]
             return (name, params, values)
         except ValueError as exc:
             raise ValueError(

src/icalendar/tests/issue_355_url_unescaping.ics

@@ -0,0 +1,33 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//ical.marudot.com//iCal Event Maker
+CALSCALE:GREGORIAN
+BEGIN:VTIMEZONE
+TZID:Europe/Berlin
+LAST-MODIFIED:20201011T015911Z
+TZURL:http://tzurl.org/zoneinfo-outlook/Europe/Berlin
+X-LIC-LOCATION:Europe/Berlin
+BEGIN:DAYLIGHT
+TZNAME:CEST
+TZOFFSETFROM:+0100
+TZOFFSETTO:+0200
+DTSTART:19700329T020000
+RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
+END:DAYLIGHT
+BEGIN:STANDARD
+TZNAME:CET
+TZOFFSETFROM:+0200
+TZOFFSETTO:+0100
+DTSTART:19701025T030000
+RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
+END:STANDARD
+END:VTIMEZONE
+BEGIN:VEVENT
+DTSTAMP:20220822T164528Z
+UID:[email protected]
+DTSTART;TZID=Europe/Berlin:20220822T120000
+DTEND;TZID=Europe/Berlin:20220822T120000
+SUMMARY:test
+DESCRIPTION:https://www.facebook.com/events/756119502186737/?acontext=%7B%22source%22%3A5%2C%22action_history%22%3A[%7B%22surface%22%3A%22page%22%2C%22mechanism%22%3A%22main_list%22%2C%22extra_data%22%3A%22%5C%22[]%5C%22%22%7D]%2C%22has_source%22%3Atrue%7D
+END:VEVENT
+END:VCALENDAR

src/icalendar/tests/test_fixed_issues.py

@@ -6,6 +6,8 @@
 import os
 import pytz
 
+HERE = os.path.dirname(__file__)
+
 
 class TestIssues(unittest.TestCase):
 
@@ -14,8 +16,7 @@ def test_issue_53(self):
         https://github.com/collective/icalendar/issues/53
         """
 
-        directory = os.path.dirname(__file__)
-        ics = open(os.path.join(directory, 'issue_53_parsing_failure.ics'),
+        ics = open(os.path.join(HERE, 'issue_53_parsing_failure.ics'),
                    'rb')
         cal = icalendar.Calendar.from_ical(ics.read())
         ics.close()
@@ -231,8 +232,7 @@ def test_issue_112(self):
         """Issue #112 - No timezone info on EXDATE
         https://github.com/collective/icalendar/issues/112
         """
-        directory = os.path.dirname(__file__)
-        path = os.path.join(directory,
+        path = os.path.join(HERE,
                             'issue_112_missing_tzinfo_on_exdate.ics')
         with open(path, 'rb') as ics:
             cal = icalendar.Calendar.from_ical(ics.read())
@@ -432,6 +432,18 @@ def test_issue_184(self):
                          b'END:VEVENT\r\n'
                          )
 
+    def test_issue_356_url_escaping(self):
+        """Test that the URLs stay intact.
+
+        see https://github.com/collective/icalendar/pull/356
+        see https://github.com/collective/icalendar/issues/355
+        """
+        ics = open(os.path.join(HERE, 'issue_53_parsing_failure.ics'), 'rb')
+        cal = icalendar.Calendar.from_ical(ics)
+        event = cal.walk(name='VEVENT')[0]
+        URL = "https://www.facebook.com/events/756119502186737/?acontext=%7B%22source%22%3A5%2C%22action_history%22%3A[%7B%22surface%22%3A%22page%22%2C%22mechanism%22%3A%22main_list%22%2C%22extra_data%22%3A%22%5C%22[]%5C%22%22%7D]%2C%22has_source%22%3Atrue%7D"
+        self.assertEqual(event["DESCRIPTION"], URL)
+
     def test_issue_237(self):
         """Issue #237 - Fail to parse timezone with non-ascii TZID"""