Viewing file:  fetch.py (6.49 KB) -rw-r--r--
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import os
import sys
import io
from optparse import OptionParser
from twisted.internet.defer import DeferredList
from twisted.internet.threads import deferToThread
from twisted.python.compat import iteritems, networkString
class FetchError(Exception):
pass
class HTTPCodeError(FetchError):
def __init__(self, http_code, body):
self.http_code = http_code
self.body = body
def __str__(self):
return "Server returned HTTP code %d" % self.http_code
def __repr__(self):
return "<HTTPCodeError http_code=%d>" % self.http_code
class PyCurlError(FetchError):
def __init__(self, error_code, message):
self.error_code = error_code
self._message = message
def __str__(self):
return "Error %d: %s" % (self.error_code, self.message)
def __repr__(self):
return "<PyCurlError args=(%d, '%s')>" % (self.error_code,
self.message)
@property
def message(self):
return self._message
def fetch(url, post=False, data="", headers={}, cainfo=None, curl=None,
connect_timeout=30, total_timeout=600, insecure=False, follow=True,
user_agent=None, proxy=None):
"""Retrieve a URL and return the content.
@param url: The url to be fetched.
@param post: If true, the POST method will be used (defaults to GET).
@param data: Data to be sent to the server as the POST content.
@param headers: Dictionary of header => value entries to be used on the
request.
@param curl: A pycurl.Curl instance to use. If not provided, one will be
created.
@param cainfo: Path to the file with CA certificates.
@param insecure: If true, perform curl using insecure option which will
not attempt to verify authenticity of the peer's certificate. (Used
during autodiscovery)
@param follow: If True, follow HTTP redirects (default True).
@param user_agent: The user-agent to set in the request.
@param proxy: The proxy url to use for the request.
"""
import pycurl
if not isinstance(data, bytes):
data = data.encode("utf-8")
output = io.BytesIO(data)
input = io.BytesIO()
if curl is None:
curl = pycurl.Curl()
# The conversion with `str()` ensures the acceptance of unicode under
# Python 2 and `networkString()` will ensure bytes for Python 3.
curl.setopt(pycurl.URL, networkString(str(url)))
if post:
curl.setopt(pycurl.POST, True)
if data:
curl.setopt(pycurl.POSTFIELDSIZE, len(data))
curl.setopt(pycurl.READFUNCTION, output.read)
if cainfo and url.startswith("https:"):
curl.setopt(pycurl.CAINFO, networkString(cainfo))
if headers:
curl.setopt(pycurl.HTTPHEADER,
["%s: %s" % pair for pair in sorted(iteritems(headers))])
if insecure:
curl.setopt(pycurl.SSL_VERIFYPEER, False)
if follow:
curl.setopt(pycurl.FOLLOWLOCATION, 1)
if user_agent is not None:
curl.setopt(pycurl.USERAGENT, networkString(user_agent))
if proxy is not None:
curl.setopt(pycurl.PROXY, networkString(proxy))
curl.setopt(pycurl.MAXREDIRS, 5)
curl.setopt(pycurl.CONNECTTIMEOUT, connect_timeout)
curl.setopt(pycurl.LOW_SPEED_LIMIT, 1)
curl.setopt(pycurl.LOW_SPEED_TIME, total_timeout)
curl.setopt(pycurl.NOSIGNAL, 1)
curl.setopt(pycurl.WRITEFUNCTION, input.write)
curl.setopt(pycurl.DNS_CACHE_TIMEOUT, 0)
curl.setopt(pycurl.ENCODING, b"gzip,deflate")
try:
curl.perform()
except pycurl.error as e:
raise PyCurlError(e.args[0], e.args[1])
body = input.getvalue()
http_code = curl.getinfo(pycurl.HTTP_CODE)
if http_code != 200:
raise HTTPCodeError(http_code, body)
return body
def fetch_async(*args, **kwargs):
"""Retrieve a URL asynchronously.
@return: A C{Deferred} resulting in the URL content.
"""
return deferToThread(fetch, *args, **kwargs)
def fetch_many_async(urls, callback=None, errback=None, **kwargs):
"""
Retrieve a list of URLs asynchronously.
@param callback: Optionally, a function that will be fired one time for
each successful URL, and will be passed its content and the URL itself.
@param errback: Optionally, a function that will be fired one time for each
failing URL, and will be passed the failure and the URL itself.
@return: A C{DeferredList} whose callback chain will be fired as soon as
all downloads have terminated. If an error occurs, the errback chain
of the C{DeferredList} will be fired immediatly.
"""
results = []
for url in urls:
result = fetch_async(url, **kwargs)
if callback:
result.addCallback(callback, url)
if errback:
result.addErrback(errback, url)
results.append(result)
return DeferredList(results, fireOnOneErrback=True, consumeErrors=True)
def url_to_filename(url, directory=None):
"""Return the last component of the given C{url}.
@param url: The URL to get the filename from.
@param directory: Optionally a path to prepend to the returned filename.
@note: Any trailing slash in the C{url} will be removed
"""
filename = url.rstrip("/").split("/")[-1]
if directory is not None:
filename = os.path.join(directory, filename)
return filename
def fetch_to_files(urls, directory, logger=None, **kwargs):
"""
Retrieve a list of URLs and save their content as files in a directory.
@param urls: The list URLs to fetch.
@param directory: The directory to save the files to, the name of the file
will equal the last fragment of the URL.
@param logger: Optional function to be used to log errors for failed URLs.
"""
def write(data, url):
filename = url_to_filename(url, directory=directory)
fd = open(filename, "wb")
fd.write(data)
fd.close()
def log_error(failure, url):
if logger:
logger("Couldn't fetch file from %s (%s)" % (
url, str(failure.value)))
return failure
return fetch_many_async(urls, callback=write, errback=log_error, **kwargs)
def test(args):
parser = OptionParser()
parser.add_option("--post", action="store_true")
parser.add_option("--data", default="")
parser.add_option("--cainfo")
options, (url,) = parser.parse_args(args)
print(fetch(url, post=options.post, data=options.data,
cainfo=options.cainfo))
if __name__ == "__main__":
test(sys.argv[1:])
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