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bpo-29654 : Support If-Modified-Since HTTP header (browser cache) (#298) 

Return 304 response if file was not modified.
This commit is contained in:
Pierre Quentel 2017-04-02 12:26:12 +02:00 committed by Serhiy Storchaka
parent efbd4ea65d
commit 351adda54b
5 changed files with 112 additions and 9 deletions
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12
Doc/library/http.server.rst
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@ -343,11 +343,13 @@ of which this module provides three different variants:
:func:`os.listdir` to scan the directory, and returns a ``404`` error
response if the :func:`~os.listdir` fails.
If the request was mapped to a file, it is opened and the contents are
returned. Any :exc:`OSError` exception in opening the requested file is
mapped to a ``404``, ``'File not found'`` error. Otherwise, the content
If the request was mapped to a file, it is opened. Any :exc:`OSError`
exception in opening the requested file is mapped to a ``404``,
``'File not found'`` error. If there was a ``'If-Modified-Since'``
header in the request, and the file was not modified after this time,
a ``304``, ``'Not Modified'`` response is sent. Otherwise, the content
type is guessed by calling the :meth:`guess_type` method, which in turn
uses the *extensions_map* variable.
uses the *extensions_map* variable, and the file contents are returned.
A ``'Content-type:'`` header with the guessed content type is output,
followed by a ``'Content-Length:'`` header with the file's size and a
@ -360,6 +362,8 @@ of which this module provides three different variants:
For example usage, see the implementation of the :func:`test` function
invocation in the :mod:`http.server` module.
.. versionchanged:: 3.7
Support of the ``'If-Modified-Since'`` header.
The :class:`SimpleHTTPRequestHandler` class can be used in the following
manner in order to create a very basic webserver serving files relative to

8
Doc/whatsnew/3.7.rst
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@ -95,6 +95,14 @@ New Modules
Improved Modules
================
http.server
-----------
:class:`~http.server.SimpleHTTPRequestHandler` supports the HTTP
If-Modified-Since header. The server returns the 304 response status if the
target file was not modified after the time specified in the header.
(Contributed by Pierre Quentel in :issue:`29654`.)
locale
------

39
Lib/http/server.py
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@ -87,6 +87,9 @@ __all__ = [
"SimpleHTTPRequestHandler", "CGIHTTPRequestHandler",
]
import argparse
import copy
import datetime
import email.utils
import html
import http.client
@ -101,8 +104,6 @@ import socketserver
import sys
import time
import urllib.parse
import copy
import argparse
from http import HTTPStatus
@ -686,12 +687,42 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
except OSError:
self.send_error(HTTPStatus.NOT_FOUND, "File not found")
return None
try:
fs = os.fstat(f.fileno())
# Use browser cache if possible
if ("If-Modified-Since" in self.headers
and "If-None-Match" not in self.headers):
# compare If-Modified-Since and time of last file modification
try:
ims = email.utils.parsedate_to_datetime(
self.headers["If-Modified-Since"])
except (TypeError, IndexError, OverflowError, ValueError):
# ignore ill-formed values
pass
else:
if ims.tzinfo is None:
# obsolete format with no timezone, cf.
# https://tools.ietf.org/html/rfc7231#section-7.1.1.1
ims = ims.replace(tzinfo=datetime.timezone.utc)
if ims.tzinfo is datetime.timezone.utc:
# compare to UTC datetime of last modification
last_modif = datetime.datetime.fromtimestamp(
fs.st_mtime, datetime.timezone.utc)
# remove microseconds, like in If-Modified-Since
last_modif = last_modif.replace(microsecond=0)
if last_modif <= ims:
self.send_response(HTTPStatus.NOT_MODIFIED)
self.end_headers()
f.close()
return None
self.send_response(HTTPStatus.OK)
self.send_header("Content-type", ctype)
fs = os.fstat(f.fileno())
self.send_header("Content-Length", str(fs[6]))
self.send_header("Last-Modified", self.date_time_string(fs.st_mtime))
self.send_header("Last-Modified",
self.date_time_string(fs.st_mtime))
self.end_headers()
return f
except:

59
Lib/test/test_httpservers.py
View File

@ -14,11 +14,14 @@ import re
import base64
import ntpath
import shutil
import urllib.parse
import email.message
import email.utils
import html
import http.client
import urllib.parse
import tempfile
import time
import datetime
from io import BytesIO
import unittest
@ -333,6 +336,13 @@ class SimpleHTTPServerTestCase(BaseTestCase):
self.base_url = '/' + self.tempdir_name
with open(os.path.join(self.tempdir, 'test'), 'wb') as temp:
temp.write(self.data)
mtime = os.fstat(temp.fileno()).st_mtime
# compute last modification datetime for browser cache tests
last_modif = datetime.datetime.fromtimestamp(mtime,
datetime.timezone.utc)
self.last_modif_datetime = last_modif.replace(microsecond=0)
self.last_modif_header = email.utils.formatdate(
last_modif.timestamp(), usegmt=True)
def tearDown(self):
try:
@ -444,6 +454,44 @@ class SimpleHTTPServerTestCase(BaseTestCase):
self.assertEqual(response.getheader('content-type'),
'application/octet-stream')
def test_browser_cache(self):
"""Check that when a request to /test is sent with the request header
If-Modified-Since set to date of last modification, the server returns
status code 304, not 200
"""
headers = email.message.Message()
headers['If-Modified-Since'] = self.last_modif_header
response = self.request(self.base_url + '/test', headers=headers)
self.check_status_and_reason(response, HTTPStatus.NOT_MODIFIED)
# one hour after last modification : must return 304
new_dt = self.last_modif_datetime + datetime.timedelta(hours=1)
headers = email.message.Message()
headers['If-Modified-Since'] = email.utils.format_datetime(new_dt,
usegmt=True)
response = self.request(self.base_url + '/test', headers=headers)
self.check_status_and_reason(response, HTTPStatus.NOT_MODIFIED)
def test_browser_cache_file_changed(self):
# with If-Modified-Since earlier than Last-Modified, must return 200
dt = self.last_modif_datetime
# build datetime object : 365 days before last modification
old_dt = dt - datetime.timedelta(days=365)
headers = email.message.Message()
headers['If-Modified-Since'] = email.utils.format_datetime(old_dt,
usegmt=True)
response = self.request(self.base_url + '/test', headers=headers)
self.check_status_and_reason(response, HTTPStatus.OK)
def test_browser_cache_with_If_None_Match_header(self):
# if If-None-Match header is present, ignore If-Modified-Since
headers = email.message.Message()
headers['If-Modified-Since'] = self.last_modif_header
headers['If-None-Match'] = "*"
response = self.request(self.base_url + '/test', headers=headers)
self.check_status_and_reason(response, HTTPStatus.OK)
def test_invalid_requests(self):
response = self.request('/', method='FOO')
self.check_status_and_reason(response, HTTPStatus.NOT_IMPLEMENTED)
@ -453,6 +501,15 @@ class SimpleHTTPServerTestCase(BaseTestCase):
response = self.request('/', method='GETs')
self.check_status_and_reason(response, HTTPStatus.NOT_IMPLEMENTED)
def test_last_modified(self):
"""Checks that the datetime returned in Last-Modified response header
is the actual datetime of last modification, rounded to the second
"""
response = self.request(self.base_url + '/test')
self.check_status_and_reason(response, HTTPStatus.OK, data=self.data)
last_modif_header = response.headers['Last-modified']
self.assertEqual(last_modif_header, self.last_modif_header)
def test_path_without_leading_slash(self):
response = self.request(self.tempdir_name + '/test')
self.check_status_and_reason(response, HTTPStatus.OK, data=self.data)

3
Misc/NEWS
View File

@ -303,6 +303,9 @@ Extension Modules
Library
-------
- bpo-29654: Support If-Modified-Since HTTP header (browser cache). Patch
by Pierre Quentel.
- bpo-29931: Fixed comparison check for ipaddress.ip_interface objects.
Patch by Sanjay Sundaresan.