/usr/share/pyshared/twill/wsgi_intercept.py is in python-twill 0.9-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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wsgi_intercept.WSGI_HTTPConnection is a replacement for
httplib.HTTPConnection that intercepts certain HTTP connections into a
WSGI application.
Use 'add_wsgi_intercept' and 'remove_wsgi_intercept' to control this behavior.
"""
import sys
from httplib import HTTPConnection
import urllib
from cStringIO import StringIO
import traceback
debuglevel = 0
# 1 basic
# 2 verbose
####
#
# Specify which hosts/ports to target for interception to a given WSGI app.
#
# For simplicity's sake, intercept ENTIRE host/port combinations;
# intercepting only specific URL subtrees gets complicated, because we don't
# have that information in the HTTPConnection.connect() function that does the
# redirection.
#
# format: key=(host, port), value=(create_app, top_url)
#
# (top_url becomes the SCRIPT_NAME)
_wsgi_intercept = {}
def add_wsgi_intercept(host, port, app_create_fn, script_name=''):
"""
Add a WSGI intercept call for host:port, using the app returned
by app_create_fn with a SCRIPT_NAME of 'script_name' (default '').
"""
_wsgi_intercept[(host, port)] = (app_create_fn, script_name)
def remove_wsgi_intercept(host, port):
"""
Remove the WSGI intercept call for (host, port).
"""
key = (host, port)
if _wsgi_intercept.has_key(key):
del _wsgi_intercept[key]
#
# make_environ: behave like a Web server. Take in 'input', and behave
# as if you're bound to 'host' and 'port'; build an environment dict
# for the WSGI app.
#
# This is where the magic happens, folks.
#
def make_environ(inp, host, port, script_name):
"""
Take 'inp' as if it were HTTP-speak being received on host:port,
and parse it into a WSGI-ok environment dictionary. Return the
dictionary.
Set 'SCRIPT_NAME' from the 'script_name' input, and, if present,
remove it from the beginning of the PATH_INFO variable.
"""
#
# parse the input up to the first blank line (or its end).
#
environ = {}
method_line = inp.readline()
content_type = None
content_length = None
cookies = []
for line in inp:
if not line.strip():
break
k, v = line.strip().split(':', 1)
v = v.lstrip()
#
# take care of special headers, and for the rest, put them
# into the environ with HTTP_ in front.
#
if k.lower() == 'content-type':
content_type = v
elif k.lower() == 'content-length':
content_length = v
elif k.lower() == 'cookie' or k.lower() == 'cookie2':
cookies.append(v)
else:
h = k.upper()
h = h.replace('-', '_')
environ['HTTP_' + h] = v
if debuglevel >= 2:
print 'HEADER:', k, v
#
# decode the method line
#
if debuglevel >= 2:
print 'METHOD LINE:', method_line
method, url, protocol = method_line.split(' ')
# clean the script_name off of the url, if it's there.
if not url.startswith(script_name):
script_name = '' # @CTB what to do -- bad URL. scrap?
else:
url = url[len(script_name):]
url = url.split('?', 1)
path_info = urllib.unquote_plus(url[0])
query_string = ""
if len(url) == 2:
query_string = urllib.unquote_plus(url[1])
if debuglevel:
print "method: %s; script_name: %s; path_info: %s; query_string: %s" % (method, script_name, path_info, query_string)
r = inp.read()
inp = StringIO(r)
#
# fill out our dictionary.
#
environ.update({ "wsgi.version" : (1,0),
"wsgi.url_scheme": "http",
"wsgi.input" : inp, # to read for POSTs
"wsgi.errors" : StringIO(),
"wsgi.multithread" : 0,
"wsgi.multiprocess" : 0,
"wsgi.run_once" : 0,
"REQUEST_METHOD" : method,
"SCRIPT_NAME" : script_name,
"PATH_INFO" : path_info,
"SERVER_NAME" : host,
"SERVER_PORT" : str(port),
"SERVER_PROTOCOL" : protocol,
"REMOTE_ADDR" : '127.0.0.1',
})
#
# query_string, content_type & length are optional.
#
if query_string:
environ['QUERY_STRING'] = query_string
else:
environ['QUERY_STRING'] = ''
if content_type:
environ['CONTENT_TYPE'] = content_type
if debuglevel >= 2:
print 'CONTENT-TYPE:', content_type
if content_length:
environ['CONTENT_LENGTH'] = content_length
if debuglevel >= 2:
print 'CONTENT-LENGTH:', content_length
#
# handle cookies.
#
if cookies:
environ['HTTP_COOKIE'] = "; ".join(cookies)
if debuglevel:
print 'WSGI environ dictionary:', environ
return environ
#
# fake socket for WSGI intercept stuff.
#
class wsgi_fake_socket:
"""
Handle HTTP traffic and stuff into a WSGI application object instead.
Note that this class assumes:
1. 'makefile' is called (by the response class) only after all of the
data has been sent to the socket by the request class;
2. non-persistent (i.e. non-HTTP/1.1) connections.
"""
def __init__(self, app, host, port, script_name):
self.app = app # WSGI app object
self.host = host
self.port = port
self.script_name = script_name # SCRIPT_NAME (app mount point)
self.inp = StringIO() # stuff written into this "socket"
self.write_results = [] # results from the 'write_fn'
self.results = None # results from running the app
self.output = StringIO() # all output from the app, incl headers
def makefile(self, *args, **kwargs):
"""
'makefile' is called by the HTTPResponse class once all of the
data has been written. So, in this interceptor class, we need to:
1. build a start_response function that grabs all the headers
returned by the WSGI app;
2. create a wsgi.input file object 'inp', containing all of the
traffic;
3. build an environment dict out of the traffic in inp;
4. run the WSGI app & grab the result object;
5. concatenate & return the result(s) read from the result object.
"""
# dynamically construct the start_response function for no good reason.
def start_response(status, headers, exc_info=None):
# construct the HTTP request.
self.output.write("HTTP/1.0 " + status + "\n")
for k, v in headers:
self.output.write('%s: %s\n' % (k, v,))
self.output.write('\n')
def write_fn(s):
self.write_results.append(s)
return write_fn
# construct the wsgi.input file from everything that's been
# written to this "socket".
inp = StringIO(self.inp.getvalue())
# build the environ dictionary.
environ = make_environ(inp, self.host, self.port, self.script_name)
# run the application.
app_result = self.app(environ, start_response)
self.result = iter(app_result)
###
# read all of the results. the trick here is to get the *first*
# bit of data from the app via the generator, *then* grab & return
# the data passed back from the 'write' function, and then return
# the generator data. this is because the 'write' fn doesn't
# necessarily get called until the first result is requested from
# the app function.
#
# see twill tests, 'test_wrapper_intercept' for a test that breaks
# if this is done incorrectly.
try:
generator_data = None
try:
generator_data = self.result.next()
finally:
for data in self.write_results:
self.output.write(data)
if generator_data:
self.output.write(generator_data)
while 1:
data = self.result.next()
self.output.write(data)
except StopIteration:
pass
if hasattr(app_result, 'close'):
app_result.close()
if debuglevel >= 2:
print "***", self.output.getvalue(), "***"
# return the concatenated results.
return StringIO(self.output.getvalue())
def sendall(self, str):
"""
Save all the traffic to self.inp.
"""
if debuglevel >= 2:
print ">>>", str, ">>>"
self.inp.write(str)
def close(self):
"Do nothing, for now."
pass
#
# WSGI_HTTPConnection
#
class WSGI_HTTPConnection(HTTPConnection):
"""
Intercept all traffic to certain hosts & redirect into a WSGI
application object.
"""
def get_app(self, host, port):
"""
Return the app object for the given (host, port).
"""
key = (host, int(port))
app, script_name = None, None
if _wsgi_intercept.has_key(key):
(app_fn, script_name) = _wsgi_intercept[key]
app = app_fn()
return app, script_name
def connect(self):
"""
Override the connect() function to intercept calls to certain
host/ports.
"""
if debuglevel:
sys.stderr.write('connect: %s, %s\n' % (self.host, self.port,))
try:
(app, script_name) = self.get_app(self.host, self.port)
if app:
if debuglevel:
sys.stderr.write('INTERCEPTING call to %s:%s\n' % \
(self.host, self.port,))
self.sock = wsgi_fake_socket(app, self.host, self.port,
script_name)
else:
HTTPConnection.connect(self)
except Exception, e:
if debuglevel: # intercept & print out tracebacks
traceback.print_exc()
raise
### DEBUGGING CODE -- to help me figure out communications stuff. ###
# (ignore me, please)
'''
import socket
class file_wrapper:
def __init__(self, fp):
self.fp = fp
def readline(self):
d = self.fp.readline()
if debuglevel:
print 'file_wrapper readline:', d
return d
def __iter__(self):
return self
def next(self):
d = self.fp.next()
if debuglevel:
print 'file_wrapper next:', d
return d
def read(self, *args):
d = self.fp.read(*args)
if debuglevel:
print 'file_wrapper read:', d
return d
def close(self):
if debuglevel:
print 'file_wrapper close'
self.fp.close()
class intercept_socket:
"""
A socket that intercepts everything written to it & read from it.
"""
def __init__(self):
for res in socket.getaddrinfo("floating.caltech.edu", 80, 0,
socket.SOCK_STREAM):
af, socktype, proto, canonname, sa = res
self.sock = socket.socket(af, socktype, proto)
self._open = True
self.sock.connect(sa)
break
def makefile(self, *args, **kwargs):
fp = self.sock.makefile('rb', 0)
return file_wrapper(fp)
def sendall(self, str):
if not self._open:
raise Exception
return self.sock.sendall(str)
def close(self):
self._open = False
'''
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