# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import time
from email.utils import parsedate_tz, mktime_tz
__all__ = [
'BaseHTTPError',
'RateLimitReachedError',
'exception_from_message'
]
[docs]class BaseHTTPError(Exception):
"""
The base exception class for all HTTP related exceptions.
"""
def __init__(self, code, message, headers=None):
self.code = code
self.message = message
self.headers = headers
# preserve old exception behavior for tests that
# look for e.args[0]
super(BaseHTTPError, self).__init__(message)
def __str__(self):
return self.message
[docs]class RateLimitReachedError(BaseHTTPError):
"""
HTTP 429 - Rate limit: you've sent too many requests for this time period.
"""
code = 429
message = '%s Rate limit exceeded' % (code)
def __init__(self, *args, **kwargs):
headers = kwargs.pop('headers', None)
super(RateLimitReachedError, self).__init__(self.code,
self.message,
headers)
if self.headers is not None:
self.retry_after = int(self.headers.get('retry-after', 0))
else:
self.retry_after = 0
_error_classes = [RateLimitReachedError]
_code_map = dict((c.code, c) for c in _error_classes)
[docs]def exception_from_message(code, message, headers=None):
"""
Return an instance of BaseHTTPException or subclass based on response code.
If headers include Retry-After, RFC 2616 says that its value may be one of
two formats: HTTP-date or delta-seconds, for example:
Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
Retry-After: 120
If Retry-After comes in HTTP-date, it'll be translated to a positive
delta-seconds value when passing it to the exception constructor.
Also, RFC 2616 says that Retry-After isn't just only applicable to 429
HTTP status, but also to other responses, like 503 and 3xx.
Usage::
raise exception_from_message(code=self.status,
message=self.parse_error(),
headers=self.headers)
"""
kwargs = {
'code': code,
'message': message,
'headers': headers
}
if headers and 'retry-after' in headers:
http_date = parsedate_tz(headers['retry-after'])
if http_date is not None:
# Convert HTTP-date to delay-seconds
delay = max(0, int(mktime_tz(http_date) - time.time()))
headers['retry-after'] = str(delay)
cls = _code_map.get(code, BaseHTTPError)
return cls(**kwargs)