Current File : //lib/python2.7/site-packages/ndg/httpsclient/utils.py
"""Utilities using NDG HTTPS Client, including a main module that can be used to
fetch from a URL.
"""
__author__ = "R B Wilkinson"
__date__ = "09/12/11"
__copyright__ = "(C) 2011 Science and Technology Facilities Council"
__license__ = "BSD - see LICENSE file in top-level directory"
__contact__ = "Philip.Kershaw@stfc.ac.uk"
__revision__ = '$Id$'
import cookielib
import httplib
import logging
from optparse import OptionParser
import os
import urllib2
from urllib2 import (HTTPHandler, HTTPCookieProcessor,
HTTPBasicAuthHandler, HTTPPasswordMgrWithDefaultRealm)
import urlparse
from ndg.httpsclient.urllib2_build_opener import build_opener
from ndg.httpsclient.https import HTTPSContextHandler
from ndg.httpsclient import ssl_context_util
log = logging.getLogger(__name__)
class AccumulatingHTTPCookieProcessor(HTTPCookieProcessor):
"""Cookie processor that adds new cookies (instead of replacing the existing
ones as HTTPCookieProcessor does)
"""
def http_request(self, request):
"""Processes cookies for a HTTP request.
@param request: request to process
@type request: urllib2.Request
@return: request
@rtype: urllib2.Request
"""
COOKIE_HEADER_NAME = "Cookie"
tmp_request = urllib2.Request(request.get_full_url(), request.data, {},
request.origin_req_host,
request.unverifiable)
self.cookiejar.add_cookie_header(tmp_request)
# Combine existing and new cookies.
new_cookies = tmp_request.get_header(COOKIE_HEADER_NAME)
if new_cookies:
if request.has_header(COOKIE_HEADER_NAME):
# Merge new cookies with existing ones.
old_cookies = request.get_header(COOKIE_HEADER_NAME)
merged_cookies = '; '.join([old_cookies, new_cookies])
request.add_unredirected_header(COOKIE_HEADER_NAME,
merged_cookies)
else:
# No existing cookies so just set new ones.
request.add_unredirected_header(COOKIE_HEADER_NAME, new_cookies)
return request
# Process cookies for HTTPS in the same way.
https_request = http_request
class URLFetchError(Exception):
"""Error fetching content from URL"""
def fetch_from_url(url, config, data=None, handlers=None):
"""Returns data retrieved from a URL.
@param url: URL to attempt to open
@type url: basestring
@param config: SSL context configuration
@type config: Configuration
@return data retrieved from URL or None
"""
return_code, return_message, response = open_url(url, config, data=data,
handlers=handlers)
if return_code and return_code == httplib.OK:
return_data = response.read()
response.close()
return return_data
else:
raise URLFetchError(return_message)
def fetch_from_url_to_file(url, config, output_file, data=None, handlers=None):
"""Writes data retrieved from a URL to a file.
@param url: URL to attempt to open
@type url: basestring
@param config: SSL context configuration
@type config: Configuration
@param output_file: output file
@type output_file: basestring
@return: tuple (
returned HTTP status code or 0 if an error occurred
returned message
boolean indicating whether access was successful)
"""
return_code, return_message, response = open_url(url, config, data=data,
handlers=handlers)
if return_code == httplib.OK:
return_data = response.read()
response.close()
outfile = open(output_file, "w")
outfile.write(return_data)
outfile.close()
return return_code, return_message, return_code == httplib.OK
def fetch_stream_from_url(url, config, data=None, handlers=None):
"""Returns data retrieved from a URL.
@param url: URL to attempt to open
@type url: basestring
@param config: SSL context configuration
@type config: Configuration
@return: data retrieved from URL or None
@rtype: file derived type
"""
return_code, return_message, response = open_url(url, config, data=data,
handlers=handlers)
if return_code and return_code == httplib.OK:
return response
else:
raise URLFetchError(return_message)
def open_url(url, config, data=None, handlers=None):
"""Attempts to open a connection to a specified URL.
@param url: URL to attempt to open
@param config: SSL context configuration
@type config: Configuration
@param data: HTTP POST data
@type data: str
@param handlers: list of custom urllib2 handlers to add to the request
@type handlers: iterable
@return: tuple (
returned HTTP status code or 0 if an error occurred
returned message or error description
response object)
"""
debuglevel = 1 if config.debug else 0
# Set up handlers for URL opener.
if config.cookie:
cj = config.cookie
else:
cj = cookielib.CookieJar()
# Use a cookie processor that accumulates cookies when redirects occur so
# that an application can redirect for authentication and retain both any
# cookies for the application and the security system (c.f.,
# urllib2.HTTPCookieProcessor which replaces cookies).
cookie_handler = AccumulatingHTTPCookieProcessor(cj)
if not handlers:
handlers = []
handlers.append(cookie_handler)
if config.debug:
http_handler = HTTPHandler(debuglevel=debuglevel)
https_handler = HTTPSContextHandler(config.ssl_context,
debuglevel=debuglevel)
handlers.extend([http_handler, https_handler])
if config.http_basicauth:
# currently only supports http basic auth
auth_handler = HTTPBasicAuthHandler(HTTPPasswordMgrWithDefaultRealm())
auth_handler.add_password(realm=None, uri=url,
user=config.httpauth[0],
passwd=config.httpauth[1])
handlers.append(auth_handler)
# Explicitly remove proxy handling if the host is one listed in the value of
# the no_proxy environment variable because urllib2 does use proxy settings
# set via http_proxy and https_proxy, but does not take the no_proxy value
# into account.
if not _should_use_proxy(url, config.no_proxy):
handlers.append(urllib2.ProxyHandler({}))
log.debug("Not using proxy")
elif config.proxies:
handlers.append(urllib2.ProxyHandler(config.proxies))
log.debug("Configuring proxies: %s" % config.proxies)
opener = build_opener(*handlers, ssl_context=config.ssl_context)
headers = config.headers
if headers is None:
headers = {}
request = urllib2.Request(url, data, headers)
# Open the URL and check the response.
return_code = 0
return_message = ''
response = None
try:
response = opener.open(request)
return_message = response.msg
return_code = response.code
if log.isEnabledFor(logging.DEBUG):
for index, cookie in enumerate(cj):
log.debug("%s : %s", index, cookie)
except urllib2.HTTPError, exc:
return_code = exc.code
return_message = "Error: %s" % exc.msg
if log.isEnabledFor(logging.DEBUG):
log.debug("%s %s", exc.code, exc.msg)
except Exception, exc:
return_message = "Error: %s" % exc.__str__()
if log.isEnabledFor(logging.DEBUG):
import traceback
log.debug(traceback.format_exc())
return (return_code, return_message, response)
def _should_use_proxy(url, no_proxy=None):
"""Determines whether a proxy should be used to open a connection to the
specified URL, based on the value of the no_proxy environment variable.
@param url: URL
@type url: basestring or urllib2.Request
"""
if no_proxy is None:
no_proxy_effective = os.environ.get('no_proxy', '')
else:
no_proxy_effective = no_proxy
urlObj = urlparse.urlparse(_url_as_string(url))
for np in [h.strip() for h in no_proxy_effective.split(',')]:
if urlObj.hostname == np:
return False
return True
def _url_as_string(url):
"""Returns the URL string from a URL value that is either a string or
urllib2.Request..
@param url: URL
@type url: basestring or urllib2.Request
@return: URL string
@rtype: basestring
"""
if isinstance(url, urllib2.Request):
return url.get_full_url()
elif isinstance(url, basestring):
return url
else:
raise TypeError("Expected type %r or %r" %
(basestring, urllib2.Request))
class Configuration(object):
"""Connection configuration.
"""
def __init__(self, ssl_context, debug=False, proxies=None, no_proxy=None,
cookie=None, http_basicauth=None, headers=None):
"""
@param ssl_context: SSL context to use with this configuration
@type ssl_context: OpenSSL.SSL.Context
@param debug: if True, output debugging information
@type debug: bool
@param proxies: proxies to use for
@type proxies: dict with basestring keys and values
@param no_proxy: hosts for which a proxy should not be used
@type no_proxy: basestring
@param cookie: cookies to set for request
@type cookie: cookielib.CookieJar
@param http_basicauth: http authentication, or None
@type http_basicauth: tuple of (username,password)
@param headers: http headers
@type headers: dict
"""
self.ssl_context = ssl_context
self.debug = debug
self.proxies = proxies
self.no_proxy = no_proxy
self.cookie = cookie
self.http_basicauth = http_basicauth
self.headers = headers
def main():
'''Utility to fetch data using HTTP or HTTPS GET from a specified URL.
'''
parser = OptionParser(usage="%prog [options] url")
parser.add_option("-c", "--certificate", dest="cert_file", metavar="FILE",
default=os.path.expanduser("~/credentials.pem"),
help="Certificate file - defaults to $HOME/credentials.pem")
parser.add_option("-k", "--private-key", dest="key_file", metavar="FILE",
default=None,
help="Private key file - defaults to the certificate file")
parser.add_option("-t", "--ca-certificate-dir", dest="ca_dir",
metavar="PATH",
default=None,
help="Trusted CA certificate file directory")
parser.add_option("-d", "--debug", action="store_true", dest="debug",
default=False,
help="Print debug information.")
parser.add_option("-p", "--post-data-file", dest="data_file",
metavar="FILE", default=None,
help="POST data file")
parser.add_option("-f", "--fetch", dest="output_file", metavar="FILE",
default=None, help="Output file")
parser.add_option("-n", "--no-verify-peer", action="store_true",
dest="no_verify_peer", default=False,
help="Skip verification of peer certificate.")
parser.add_option("-a", "--basicauth", dest="auth", metavar="USER:PASSWD",
default=None,
help="HTTP authentication credentials")
parser.add_option("--header", action="append", dest="headers",
metavar="HEADER: VALUE",
help="Add HTTP header to request")
(options, args) = parser.parse_args()
if len(args) != 1:
parser.error("Incorrect number of arguments")
url = args[0]
if options.debug:
logging.getLogger().setLevel(logging.DEBUG)
if options.key_file and os.path.exists(options.key_file):
key_file = options.key_file
else:
key_file = None
if options.cert_file and os.path.exists(options.cert_file):
cert_file = options.cert_file
else:
cert_file = None
if options.ca_dir and os.path.exists(options.ca_dir):
ca_dir = options.ca_dir
else:
ca_dir = None
verify_peer = not options.no_verify_peer
if options.data_file and os.path.exists(options.data_file):
data_file = open(options.data_file)
data = data_file.read()
data_file.close()
else:
data = None
if options.basicauth:
http_basicauth = options.auth.split(':', 1)
else:
http_basicauth = None
headers = {}
if options.headers:
for h in options.headers:
key, val = h.split(':', 1)
headers[key.strip()] = val.lstrip()
# If a private key file is not specified, the key is assumed to be stored in
# the certificate file.
ssl_context = ssl_context_util.make_ssl_context(key_file,
cert_file,
None,
ca_dir,
verify_peer,
url)
config = Configuration(ssl_context,
options.debug,
http_basicauth=http_basicauth,
headers=headers)
if options.output_file:
return_code, return_message = fetch_from_url_to_file(
url,
config,
options.output_file,
data)[:2]
raise SystemExit(return_code, return_message)
else:
data = fetch_from_url(url, config)
print(data)
if __name__=='__main__':
logging.basicConfig()
main()
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