Develop Reference

Trying to send Python HTTPConnection content after accepting 100-continue header

I've been trying to debug a Python script I've inherited. It's trying to POST a CSV to a website via HTTPLib. The problem, as far as I can tell, is that HTTPLib doesn't handle receiving a 100-continue response, as per python http client stuck on 100 continue. Similarly to that post, this "Just Works" via Curl, but for various reasons we need this to run from a Python script.
I've tried to employ the work-around as detailed in an answer on that post, but I can't find a way to use that to submit the CSV after accepting the 100-continue response.
The general flow needs to be like this:
-> establish connection
-> send data including "expect: 100-continue" header, but not including the JSON body yet
<- receive "100-continue"
-> using the same connection, send the JSON body of the request
<- receive the 200 OK message, in a JSON response with other information
Here's the code in its current state, with my 10+ other commented remnants of other attempted workarounds removed:
#!/usr/bin/env python
import os
import ssl
import http.client
import binascii
import logging
import json
#classes taken from https://stackoverflow.com/questions/38084993/python-http-client-stuck-on-100-continue
class ContinueHTTPResponse(http.client.HTTPResponse):
def _read_status(self, *args, **kwargs):
version, status, reason = super()._read_status(*args, **kwargs)
if status == 100:
status = 199
return version, status, reason
def begin(self, *args, **kwargs):
super().begin(*args, **kwargs)
if self.status == 199:
self.status = 100
def _check_close(self, *args, **kwargs):
return super()._check_close(*args, **kwargs) and self.status != 100
class ContinueHTTPSConnection(http.client.HTTPSConnection):
response_class = ContinueHTTPResponse
def getresponse(self, *args, **kwargs):
logging.debug('running getresponse')
response = super().getresponse(*args, **kwargs)
if response.status == 100:
setattr(self, '_HTTPConnection__state', http.client._CS_REQ_SENT)
setattr(self, '_HTTPConnection__response', None)
return response
def uploadTradeIngest(ingestFile, certFile, certPass, host, port, url):
boundary = binascii.hexlify(os.urandom(16)).decode("ascii")
headers = {
"accept": "application/json",
"Content-Type": "multipart/form-data; boundary=%s" % boundary,
"Expect": "100-continue",
}
context = ssl.SSLContext(ssl.PROTOCOL_SSLv23)
context.load_cert_chain(certfile=certFile, password=certPass)
connection = ContinueHTTPSConnection(
host, port=port, context=context)
with open(ingestFile, "r") as fh:
ingest = fh.read()
## Create form-data boundary
ingest = "--%s\r\nContent-Disposition: form-data; " % boundary + \
"name=\"file\"; filename=\"%s\"" % os.path.basename(ingestFile) + \
"\r\n\r\n%s\r\n--%s--\r\n" % (ingest, boundary)
print("pre-request")
connection.request(
method="POST", url=url, headers=headers)
print("post-request")
#resp = connection.getresponse()
resp = connection.getresponse()
if resp.status == http.client.CONTINUE:
resp.read()
print("pre-send ingest")
ingest = json.dumps(ingest)
ingest = ingest.encode()
print(ingest)
connection.send(ingest)
print("post-send ingest")
resp = connection.getresponse()
print("response1")
print(resp)
print("response2")
print(resp.read())
print("response3")
return resp.read()
But this simply returns a 400 "Bad Request" response. The problem (I think) lies with the formatting and type of the "ingest" variable. If I don't run it through json.dumps() and encode() then the HTTPConnection.send() method rejects it:
ERROR: Got error: memoryview: a bytes-like object is required, not 'str'
I had a look at using the Requests library instead, but I couldn't get it to use my local certificate bundle to accept the site's certificate. I have a full chain with an encrypted key, which I did decrypt, but still ran into constant SSL_VERIFY errors from Requests. If you have a suggestion to solve my current problem with Requests, I'm happy to go down that path too.
How can I use HTTPLib or Requests (or any other libraries) to achieve what I need to achieve?

In case anyone comes across this problem in future, I ended up working around it with a bit of a kludge. I tried HTTPLib, Requests, and URLLib3 are all known to not handle the 100-continue header, so... I just wrote a Python wrapper around Curl via the subprocess.run() function, like this:
def sendReq(upFile):
sendFile=f"file=#{upFile}"
completed = subprocess.run([
curlPath,
'--cert',
args.cert,
'--key',
args.key,
targetHost,
'-H',
'accept: application/json',
'-H',
'Content-Type: multipart/form-data',
'-H',
'Expect: 100-continue',
'-F',
sendFile,
'-s'
], stdout=subprocess.PIPE, universal_newlines=True)
return completed.stdout
The only issue I had with this was that it fails if Curl was built against the NSS libraries, which I resolved by including a statically-built Curl binary with the package, the path to which is contained in the curlPath variable in the code. I obtained this binary from this Github repo.

Conditionally mock httputil.get method on specific url with path json

I have http get method mocked so to get the response from the url without actually sending the url:
def get(url, retries=None, back_off_factor=None, max_back_off=None, timeout=None, response_encoding=None,
retry_on_timeout=None, retry_codes=None, **kwargs):
return _make_request("GET", url,
retries=retries, back_off_factor=back_off_factor,
max_back_off=max_back_off,
timeout=timeout,
response_encoding=response_encoding,
retry_on_timeout=retry_on_timeout,
retry_codes=retry_codes,
**kwargs)
#patch('lib.httputil.get')
def test_harvest(self, mock_get):
articles = json.load(json_file)
# Configure the mock to return a response with an OK status code. Also, the mock should have
# a `json()` method that returns a list of todos.
mock_get.return_value = Mock(ok=True)
mock_get.return_value.json.return_value = articles
mock_get.return_value.status_code = 200
the_rest_of_the_test()
But I realized I need to mock it only if the URL is specific. I know I could use new keyword and do:
def mock_get(self, url):
if url == MY_SPECIFIC_URL:
{...}
else:
self.old_get(url)
{...}
with mock.patch('portality.lib.httputil.get', new=self.mock_get):
the_rest_of_the_test()
but I don't really know how to mock the Response object so that it returns the correct status code and gives the correct result to .json() method.
How can I use both of these approaches altogether so that on one hand I can use the conditional but on the other mock the Response in easy way?

I suggest that you use the requests library, along with responses which is specifically meant for returning the desired HTTP responses.
You can mock specific urls:
import responses
import requests
#responses.activate
def test_simple():
responses.add(responses.GET, 'http://twitter.com/api/1/foobar',
json={'error': 'not found'}, status=404)
resp = requests.get('http://twitter.com/api/1/foobar')
assert resp.json() == {"error": "not found"}
assert len(responses.calls) == 1
assert responses.calls[0].request.url == 'http://twitter.com/api/1/foobar'
assert responses.calls[0].response.text == '{"error": "not found"}'
And you can exclude other urls:
responses.add_passthru(re.compile('https://percy.io/\\w+'))

Python - the most efficient way to get head request in python 3

I found this code and it seemed to reliable and efficient to me but unfortunately it's for python2 and also it uses urllib2 while everybody is saying requests is faster. What would be the equivalent code of the following (or something more efficient or more reliable) in python 3?
#!/usr/bin/env python
#-*- coding:utf-8 -*-
import sys
import urllib2
# This script uses HEAD requests (with fallback in case of 405)
# to follow the redirect path up to the real URL
# (c) 2012 Filippo Valsorda - FiloSottile
# Released under the GPL license
class HeadRequest(urllib2.Request):
def get_method(self):
return "HEAD"
class HEADRedirectHandler(urllib2.HTTPRedirectHandler):
"""
Subclass the HTTPRedirectHandler to make it use our
HeadRequest also on the redirected URL
"""
def redirect_request(self, req, fp, code, msg, headers, newurl):
if code in (301, 302, 303, 307):
newurl = newurl.replace(' ', '%20')
newheaders = dict((k,v) for k,v in req.headers.items()
if k.lower() not in ("content-length", "content-type"))
return HeadRequest(newurl,
headers=newheaders,
origin_req_host=req.get_origin_req_host(),
unverifiable=True)
else:
raise urllib2.HTTPError(req.get_full_url(), code, msg, headers, fp)
class HTTPMethodFallback(urllib2.BaseHandler):
"""
Fallback to GET if HEAD is not allowed (405 HTTP error)
"""
def http_error_405(self, req, fp, code, msg, headers):
fp.read()
fp.close()
newheaders = dict((k,v) for k,v in req.headers.items()
if k.lower() not in ("content-length", "content-type"))
return self.parent.open(urllib2.Request(req.get_full_url(),
headers=newheaders,
origin_req_host=req.get_origin_req_host(),
unverifiable=True))
# Build our opener
opener = urllib2.OpenerDirector()
for handler in [urllib2.HTTPHandler, urllib2.HTTPDefaultErrorHandler,
HTTPMethodFallback, HEADRedirectHandler,
urllib2.HTTPErrorProcessor, urllib2.HTTPSHandler]:
opener.add_handler(handler())
response = opener.open(HeadRequest(sys.argv[1]))
print(response.geturl())
By the way Head request is not actually what I need. I only want to know if the link is broken(In some sites if you give them a broken code they will redirect you back to the main page of the site and I want my code to recognize this too) and head request is the most efficient solution that came to my mind for this so if you know any better way I'd also appreciate that.

Take a look at Requests: http://docs.python-requests.org/en/master/
To do a head request, you simply go:
import requests
r=requests.head('http://www.example.com')
Then you can access the object for what you need. For example, the status code:
print r.status_code
Update:
If you are wanting to check to see if a page is live, you'll want to do a GET request. I've seen cases of HEAD requests returning a 200 response and on the same URL, a GET request returning a 500

Fetch a file from a local url with Python requests?

I am using Python's requests library in one method of my application. The body of the method looks like this:
def handle_remote_file(url, **kwargs):
response = requests.get(url, ...)
buff = StringIO.StringIO()
buff.write(response.content)
...
return True
I'd like to write some unit tests for that method, however, what I want to do is to pass a fake local url such as:
class RemoteTest(TestCase):
def setUp(self):
self.url = 'file:///tmp/dummy.txt'
def test_handle_remote_file(self):
self.assertTrue(handle_remote_file(self.url))
When I call requests.get with a local url, I got the KeyError exception below:
requests.get('file:///tmp/dummy.txt')
/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/requests/packages/urllib3/poolmanager.pyc in connection_from_host(self, host, port, scheme)
76
77 # Make a fresh ConnectionPool of the desired type
78 pool_cls = pool_classes_by_scheme[scheme]
79 pool = pool_cls(host, port, **self.connection_pool_kw)
80
KeyError: 'file'
The question is how can I pass a local url to requests.get?
PS: I made up the above example. It possibly contains many errors.

As #WooParadog explained requests library doesn't know how to handle local files. Although, current version allows to define transport adapters.
Therefore you can simply define you own adapter which will be able to handle local files, e.g.:
from requests_testadapter import Resp
import os
class LocalFileAdapter(requests.adapters.HTTPAdapter):
def build_response_from_file(self, request):
file_path = request.url[7:]
with open(file_path, 'rb') as file:
buff = bytearray(os.path.getsize(file_path))
file.readinto(buff)
resp = Resp(buff)
r = self.build_response(request, resp)
return r
def send(self, request, stream=False, timeout=None,
verify=True, cert=None, proxies=None):
return self.build_response_from_file(request)
requests_session = requests.session()
requests_session.mount('file://', LocalFileAdapter())
requests_session.get('file://<some_local_path>')
I'm using requests-testadapter module in the above example.

Here's a transport adapter I wrote which is more featureful than b1r3k's and has no additional dependencies beyond Requests itself. I haven't tested it exhaustively yet, but what I have tried seems to be bug-free.
import requests
import os, sys
if sys.version_info.major < 3:
from urllib import url2pathname
else:
from urllib.request import url2pathname
class LocalFileAdapter(requests.adapters.BaseAdapter):
"""Protocol Adapter to allow Requests to GET file:// URLs
#todo: Properly handle non-empty hostname portions.
"""
#staticmethod
def _chkpath(method, path):
"""Return an HTTP status for the given filesystem path."""
if method.lower() in ('put', 'delete'):
return 501, "Not Implemented" # TODO
elif method.lower() not in ('get', 'head'):
return 405, "Method Not Allowed"
elif os.path.isdir(path):
return 400, "Path Not A File"
elif not os.path.isfile(path):
return 404, "File Not Found"
elif not os.access(path, os.R_OK):
return 403, "Access Denied"
else:
return 200, "OK"
def send(self, req, **kwargs): # pylint: disable=unused-argument
"""Return the file specified by the given request
#type req: C{PreparedRequest}
#todo: Should I bother filling `response.headers` and processing
If-Modified-Since and friends using `os.stat`?
"""
path = os.path.normcase(os.path.normpath(url2pathname(req.path_url)))
response = requests.Response()
response.status_code, response.reason = self._chkpath(req.method, path)
if response.status_code == 200 and req.method.lower() != 'head':
try:
response.raw = open(path, 'rb')
except (OSError, IOError) as err:
response.status_code = 500
response.reason = str(err)
if isinstance(req.url, bytes):
response.url = req.url.decode('utf-8')
else:
response.url = req.url
response.request = req
response.connection = self
return response
def close(self):
pass
(Despite the name, it was completely written before I thought to check Google, so it has nothing to do with b1r3k's.) As with the other answer, follow this with:
requests_session = requests.session()
requests_session.mount('file://', LocalFileAdapter())
r = requests_session.get('file:///path/to/your/file')

The easiest way seems using requests-file.
https://github.com/dashea/requests-file (available through PyPI too)
"Requests-File is a transport adapter for use with the Requests Python library to allow local filesystem access via file:// URLs."
This in combination with requests-html is pure magic :)

packages/urllib3/poolmanager.py pretty much explains it. Requests doesn't support local url.
pool_classes_by_scheme = {
'http': HTTPConnectionPool,
'https': HTTPSConnectionPool,
}

In a recent project, I've had the same issue. Since requests doesn't support the "file" scheme, I'll patch our code to load the content locally. First, I define a function to replace requests.get:
def local_get(self, url):
"Fetch a stream from local files."
p_url = six.moves.urllib.parse.urlparse(url)
if p_url.scheme != 'file':
raise ValueError("Expected file scheme")
filename = six.moves.urllib.request.url2pathname(p_url.path)
return open(filename, 'rb')
Then, somewhere in test setup or decorating the test function, I use mock.patch to patch the get function on requests:
#mock.patch('requests.get', local_get)
def test_handle_remote_file(self):
...
This technique is somewhat brittle -- it doesn't help if the underlying code calls requests.request or constructs a Session and calls that. There may be a way to patch requests at a lower level to support file: URLs, but in my initial investigation, there didn't seem to be an obvious hook point, so I went with this simpler approach.

To load a file from a local URL, e.g. an image file you can do this:
import urllib
from PIL import Image
Image.open(urllib.request.urlopen('file:///path/to/your/file.png'))

I think simple solution for this will be creating temporary http server using python and using it.
Put all your files in temporary folder eg. tempFolder
Go to that directory and create a temporary http server in terminal/cmd as per your OS using command python -m http.server 8000 (Note 8000 is port no.)
This will you give you a link to http server. You can access it from http://127.0.0.1:8000/
Open your desired file in browser and copy the link to your url.

How do I unit test a module that relies on urllib2?

I've got a piece of code that I can't figure out how to unit test! The module pulls content from external XML feeds (twitter, flickr, youtube, etc.) with urllib2. Here's some pseudo-code for it:
params = (url, urlencode(data),) if data else (url,)
req = Request(*params)
response = urlopen(req)
#check headers, content-length, etc...
#parse the response XML with lxml...
My first thought was to pickle the response and load it for testing, but apparently urllib's response object is unserializable (it raises an exception).
Just saving the XML from the response body isn't ideal, because my code uses the header information too. It's designed to act on a response object.
And of course, relying on an external source for data in a unit test is a horrible idea.
So how do I write a unit test for this?

urllib2 has a functions called build_opener() and install_opener() which you should use to mock the behaviour of urlopen()
import urllib2
from StringIO import StringIO
def mock_response(req):
if req.get_full_url() == "http://example.com":
resp = urllib2.addinfourl(StringIO("mock file"), "mock message", req.get_full_url())
resp.code = 200
resp.msg = "OK"
return resp
class MyHTTPHandler(urllib2.HTTPHandler):
def http_open(self, req):
print "mock opener"
return mock_response(req)
my_opener = urllib2.build_opener(MyHTTPHandler)
urllib2.install_opener(my_opener)
response=urllib2.urlopen("http://example.com")
print response.read()
print response.code
print response.msg

It would be best if you could write a mock urlopen (and possibly Request) which provides the minimum required interface to behave like urllib2's version. You'd then need to have your function/method which uses it able to accept this mock urlopen somehow, and use urllib2.urlopen otherwise.
This is a fair amount of work, but worthwhile. Remember that python is very friendly to ducktyping, so you just need to provide some semblance of the response object's properties to mock it.
For example:
class MockResponse(object):
def __init__(self, resp_data, code=200, msg='OK'):
self.resp_data = resp_data
self.code = code
self.msg = msg
self.headers = {'content-type': 'text/xml; charset=utf-8'}
def read(self):
return self.resp_data
def getcode(self):
return self.code
# Define other members and properties you want
def mock_urlopen(request):
return MockResponse(r'<xml document>')
Granted, some of these are difficult to mock, because for example I believe the normal "headers" is an HTTPMessage which implements fun stuff like case-insensitive header names. But, you might be able to simply construct an HTTPMessage with your response data.

Build a separate class or module responsible for communicating with your external feeds.
Make this class able to be a test double. You're using python, so you're pretty golden there; if you were using C#, I'd suggest either in interface or virtual methods.
In your unit test, insert a test double of the external feed class. Test that your code uses the class correctly, assuming that the class does the work of communicating with your external resources correctly. Have your test double return fake data rather than live data; test various combinations of the data and of course the possible exceptions urllib2 could throw.
Aand... that's it.
You can't effectively automate unit tests that rely on external sources, so you're best off not doing it. Run an occasional integration test on your communication module, but don't include those tests as part of your automated tests.
Edit:
Just a note on the difference between my answer and #Crast's answer. Both are essentially correct, but they involve different approaches. In Crast's approach, you use a test double on the library itself. In my approach, you abstract the use of the library away into a separate module and test double that module.
Which approach you use is entirely subjective; there's no "correct" answer there. I prefer my approach because it allows me to build more modular, flexible code, something I value. But it comes at a cost in terms of additional code to write, something that may not be valued in many agile situations.

You can use pymox to mock the behavior of anything and everything in the urllib2 (or any other) package. It's 2010, you shouldn't be writing your own mock classes.

I think the easiest thing to do is to actually create a simple web server in your unit test. When you start the test, create a new thread that listens on some arbitrary port and when a client connects just returns a known set of headers and XML, then terminates.
I can elaborate if you need more info.
Here's some code:
import threading, SocketServer, time
# a request handler
class SimpleRequestHandler(SocketServer.BaseRequestHandler):
def handle(self):
data = self.request.recv(102400) # token receive
senddata = file(self.server.datafile).read() # read data from unit test file
self.request.send(senddata)
time.sleep(0.1) # make sure it finishes receiving request before closing
self.request.close()
def serve_data(datafile):
server = SocketServer.TCPServer(('127.0.0.1', 12345), SimpleRequestHandler)
server.datafile = datafile
http_server_thread = threading.Thread(target=server.handle_request())
To run your unit test, call serve_data() then call your code that requests a URL that looks like http://localhost:12345/anythingyouwant.

Why not just mock a website that returns the response you expect? then start the server in a thread in setup and kill it in the teardown. I ended up doing this for testing code that would send email by mocking an smtp server and it works great. Surely something more trivial could be done for http...
from smtpd import SMTPServer
from time import sleep
import asyncore
SMTP_PORT = 6544
class MockSMTPServer(SMTPServer):
def __init__(self, localaddr, remoteaddr, cb = None):
self.cb = cb
SMTPServer.__init__(self, localaddr, remoteaddr)
def process_message(self, peer, mailfrom, rcpttos, data):
print (peer, mailfrom, rcpttos, data)
if self.cb:
self.cb(peer, mailfrom, rcpttos, data)
self.close()
def start_smtp(cb, port=SMTP_PORT):
def smtp_thread():
_smtp = MockSMTPServer(("127.0.0.1", port), (None, 0), cb)
asyncore.loop()
return Thread(None, smtp_thread)
def test_stuff():
#.......snip noise
email_result = None
def email_back(*args):
email_result = args
t = start_smtp(email_back)
t.start()
sleep(1)
res.form["email"]= self.admin_email
res = res.form.submit()
assert res.status_int == 302,"should've redirected"
sleep(1)
assert email_result is not None, "didn't get an email"

Trying to improve a bit on #john-la-rooy answer, I've made a small class allowing simple mocking for unit tests
Should work with python 2 and 3
try:
import urllib.request as urllib
except ImportError:
import urllib2 as urllib
from io import BytesIO
class MockHTTPHandler(urllib.HTTPHandler):
def mock_response(self, req):
url = req.get_full_url()
print("incomming request:", url)
if url.endswith('.json'):
resdata = b'[{"hello": "world"}]'
headers = {'Content-Type': 'application/json'}
resp = urllib.addinfourl(BytesIO(resdata), header, url, 200)
resp.msg = "OK"
return resp
raise RuntimeError('Unhandled URL', url)
http_open = mock_response
#classmethod
def install(cls):
previous = urllib._opener
urllib.install_opener(urllib.build_opener(cls))
return previous
#classmethod
def remove(cls, previous=None):
urllib.install_opener(previous)
Used like this:
class TestOther(unittest.TestCase):
def setUp(self):
previous = MockHTTPHandler.install()
self.addCleanup(MockHTTPHandler.remove, previous)