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# Copyright (c) 2005, 2006 Allan Saddi <allan@saddi.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $Id$
__author__ = 'Allan Saddi <allan@saddi.com>'
__version__ = '$Revision$'
import sys
import logging
import socket
import select
import errno
import cStringIO as StringIO
import signal
import datetime
import os
# Threads are required. If you want a non-threaded (forking) version, look at
# SWAP <http://www.idyll.org/~t/www-tools/wsgi/>.
import thread
import threading
__all__ = ['BaseSCGIServer']
class NoDefault(object):
pass
# The main classes use this name for logging.
LoggerName = 'scgi-wsgi'
# Set up module-level logger.
console = logging.StreamHandler()
console.setLevel(logging.DEBUG)
console.setFormatter(logging.Formatter('%(asctime)s : %(message)s',
'%Y-%m-%d %H:%M:%S'))
logging.getLogger(LoggerName).addHandler(console)
del console
class ProtocolError(Exception):
"""
Exception raised when the server does something unexpected or
sends garbled data. Usually leads to a Connection closing.
"""
pass
def recvall(sock, length):
"""
Attempts to receive length bytes from a socket, blocking if necessary.
(Socket may be blocking or non-blocking.)
"""
dataList = []
recvLen = 0
while length:
try:
data = sock.recv(length)
except socket.error, e:
if e[0] == errno.EAGAIN:
select.select([sock], [], [])
continue
else:
raise
if not data: # EOF
break
dataList.append(data)
dataLen = len(data)
recvLen += dataLen
length -= dataLen
return ''.join(dataList), recvLen
def readNetstring(sock):
"""
Attempt to read a netstring from a socket.
"""
# First attempt to read the length.
size = ''
while True:
try:
c = sock.recv(1)
except socket.error, e:
if e[0] == errno.EAGAIN:
select.select([sock], [], [])
continue
else:
raise
if c == ':':
break
if not c:
raise EOFError
size += c
# Try to decode the length.
try:
size = int(size)
if size < 0:
raise ValueError
except ValueError:
raise ProtocolError, 'invalid netstring length'
# Now read the string.
s, length = recvall(sock, size)
if length < size:
raise EOFError
# Lastly, the trailer.
trailer, length = recvall(sock, 1)
if length < 1:
raise EOFError
if trailer != ',':
raise ProtocolError, 'invalid netstring trailer'
return s
class StdoutWrapper(object):
"""
Wrapper for sys.stdout so we know if data has actually been written.
"""
def __init__(self, stdout):
self._file = stdout
self.dataWritten = False
def write(self, data):
if data:
self.dataWritten = True
self._file.write(data)
def writelines(self, lines):
for line in lines:
self.write(line)
def __getattr__(self, name):
return getattr(self._file, name)
class Request(object):
"""
Encapsulates data related to a single request.
Public attributes:
environ - Environment variables from web server.
stdin - File-like object representing the request body.
stdout - File-like object for writing the response.
"""
def __init__(self, conn, environ, input, output):
self._conn = conn
self.environ = environ
self.stdin = input
self.stdout = StdoutWrapper(output)
self.logger = logging.getLogger(LoggerName)
def run(self):
self.logger.info('%s %s%s',
self.environ['REQUEST_METHOD'],
self.environ.get('SCRIPT_NAME', ''),
self.environ.get('PATH_INFO', ''))
start = datetime.datetime.now()
try:
self._conn.server.handler(self)
except:
self.logger.exception('Exception caught from handler')
if not self.stdout.dataWritten:
self._conn.server.error(self)
end = datetime.datetime.now()
handlerTime = end - start
self.logger.debug('%s %s%s done (%.3f secs)',
self.environ['REQUEST_METHOD'],
self.environ.get('SCRIPT_NAME', ''),
self.environ.get('PATH_INFO', ''),
handlerTime.seconds +
handlerTime.microseconds / 1000000.0)
class Connection(object):
"""
Represents a single client (web server) connection. A single request
is handled, after which the socket is closed.
"""
def __init__(self, sock, addr, server):
self._sock = sock
self._addr = addr
self.server = server
self.logger = logging.getLogger(LoggerName)
def run(self):
if len(self._addr) == 2:
self.logger.debug('Connection starting up (%s:%d)',
self._addr[0], self._addr[1])
try:
self.processInput()
except (EOFError, KeyboardInterrupt):
pass
except ProtocolError, e:
self.logger.error("Protocol error '%s'", str(e))
except:
self.logger.exception('Exception caught in Connection')
if len(self._addr) == 2:
self.logger.debug('Connection shutting down (%s:%d)',
self._addr[0], self._addr[1])
# All done!
self._sock.close()
def processInput(self):
# Read headers
headers = readNetstring(self._sock)
headers = headers.split('\x00')[:-1]
if len(headers) % 2 != 0:
raise ProtocolError, 'invalid headers'
environ = {}
for i in range(len(headers) / 2):
environ[headers[2*i]] = headers[2*i+1]
clen = environ.get('CONTENT_LENGTH')
if clen is None:
raise ProtocolError, 'missing CONTENT_LENGTH'
try:
clen = int(clen)
if clen < 0:
raise ValueError
except ValueError:
raise ProtocolError, 'invalid CONTENT_LENGTH'
self._sock.setblocking(1)
if clen:
input = self._sock.makefile('r')
else:
# Empty input.
input = StringIO.StringIO()
# stdout
output = self._sock.makefile('w')
# Allocate Request
req = Request(self, environ, input, output)
# Run it.
req.run()
output.close()
input.close()
class BaseSCGIServer(object):
# What Request class to use.
requestClass = Request
def __init__(self, application, scriptName='', environ=None,
multithreaded=True, multiprocess=False,
bindAddress=('localhost', 4000), umask=None,
allowedServers=NoDefault,
loggingLevel=logging.INFO, debug=True):
"""
scriptName is the initial portion of the URL path that "belongs"
to your application. It is used to determine PATH_INFO (which doesn't
seem to be passed in). An empty scriptName means your application
is mounted at the root of your virtual host.
environ, which must be a dictionary, can contain any additional
environment variables you want to pass to your application.
Set multithreaded to False if your application is not thread-safe.
Set multiprocess to True to explicitly set wsgi.multiprocess to
True. (Only makes sense with threaded servers.)
bindAddress is the address to bind to, which must be a string or
a tuple of length 2. If a tuple, the first element must be a string,
which is the host name or IPv4 address of a local interface. The
2nd element of the tuple is the port number. If a string, it will
be interpreted as a filename and a UNIX socket will be opened.
If binding to a UNIX socket, umask may be set to specify what
the umask is to be changed to before the socket is created in the
filesystem. After the socket is created, the previous umask is
restored.
allowedServers must be None or a list of strings representing the
IPv4 addresses of servers allowed to connect. None means accept
connections from anywhere. By default, it is a list containing
the single item '127.0.0.1'.
loggingLevel sets the logging level of the module-level logger.
"""
if environ is None:
environ = {}
self.application = application
self.scriptName = scriptName
self.environ = environ
self.multithreaded = multithreaded
self.multiprocess = multiprocess
self.debug = debug
self._bindAddress = bindAddress
self._umask = umask
if allowedServers is NoDefault:
allowedServers = ['127.0.0.1']
self._allowedServers = allowedServers
# Used to force single-threadedness.
self._appLock = thread.allocate_lock()
self.logger = logging.getLogger(LoggerName)
self.logger.setLevel(loggingLevel)
def _setupSocket(self):
"""Creates and binds the socket for communication with the server."""
oldUmask = None
if type(self._bindAddress) is str:
# Unix socket
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
try:
os.unlink(self._bindAddress)
except OSError:
pass
if self._umask is not None:
oldUmask = os.umask(self._umask)
else:
# INET socket
assert type(self._bindAddress) is tuple
assert len(self._bindAddress) == 2
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(self._bindAddress)
sock.listen(socket.SOMAXCONN)
if oldUmask is not None:
os.umask(oldUmask)
return sock
def _cleanupSocket(self, sock):
"""Closes the main socket."""
sock.close()
def _isClientAllowed(self, addr):
ret = self._allowedServers is None or \
len(addr) != 2 or \
(len(addr) == 2 and addr[0] in self._allowedServers)
if not ret:
self.logger.warning('Server connection from %s disallowed',
addr[0])
return ret
def handler(self, request):
"""
WSGI handler. Sets up WSGI environment, calls the application,
and sends the application's response.
"""
environ = request.environ
environ.update(self.environ)
environ['wsgi.version'] = (1,0)
environ['wsgi.input'] = request.stdin
environ['wsgi.errors'] = sys.stderr
environ['wsgi.multithread'] = self.multithreaded
environ['wsgi.multiprocess'] = self.multiprocess
environ['wsgi.run_once'] = False
if environ.get('HTTPS', 'off') in ('on', '1'):
environ['wsgi.url_scheme'] = 'https'
else:
environ['wsgi.url_scheme'] = 'http'
self._sanitizeEnv(environ)
headers_set = []
headers_sent = []
result = None
def write(data):
assert type(data) is str, 'write() argument must be string'
assert headers_set, 'write() before start_response()'
if not headers_sent:
status, responseHeaders = headers_sent[:] = headers_set
found = False
for header,value in responseHeaders:
if header.lower() == 'content-length':
found = True
break
if not found and result is not None:
try:
if len(result) == 1:
responseHeaders.append(('Content-Length',
str(len(data))))
except:
pass
s = 'Status: %s\r\n' % status
for header in responseHeaders:
s += '%s: %s\r\n' % header
s += '\r\n'
request.stdout.write(s)
request.stdout.write(data)
request.stdout.flush()
def start_response(status, response_headers, exc_info=None):
if exc_info:
try:
if headers_sent:
# Re-raise if too late
raise exc_info[0], exc_info[1], exc_info[2]
finally:
exc_info = None # avoid dangling circular ref
else:
assert not headers_set, 'Headers already set!'
assert type(status) is str, 'Status must be a string'
assert len(status) >= 4, 'Status must be at least 4 characters'
assert int(status[:3]), 'Status must begin with 3-digit code'
assert status[3] == ' ', 'Status must have a space after code'
assert type(response_headers) is list, 'Headers must be a list'
if __debug__:
for name,val in response_headers:
assert type(name) is str, 'Header names must be strings'
assert type(val) is str, 'Header values must be strings'
headers_set[:] = [status, response_headers]
return write
if not self.multithreaded:
self._appLock.acquire()
try:
try:
result = self.application(environ, start_response)
try:
for data in result:
if data:
write(data)
if not headers_sent:
write('') # in case body was empty
finally:
if hasattr(result, 'close'):
result.close()
except socket.error, e:
if e[0] != errno.EPIPE:
raise # Don't let EPIPE propagate beyond server
finally:
if not self.multithreaded:
self._appLock.release()
def _sanitizeEnv(self, environ):
"""Fill-in/deduce missing values in environ."""
# Namely SCRIPT_NAME/PATH_INFO
scriptName = environ.get('WSGI_SCRIPT_NAME')
if scriptName is None:
scriptName = self.scriptName
elif scriptName.lower() == 'none':
scriptName = None
if scriptName is None:
# Do nothing (most likely coming from cgi2scgi)
return
value = environ['SCRIPT_NAME']
# Pull PATH_INFO from environ, if it exists. (cgi2scgi actually
# passes it in.)
value += environ.get('PATH_INFO', '')
if not value.startswith(scriptName):
self.logger.warning('scriptName does not match request URI')
environ['PATH_INFO'] = value[len(scriptName):]
environ['SCRIPT_NAME'] = scriptName
if not environ.has_key('QUERY_STRING'):
environ['QUERY_STRING'] = ''
def error(self, request):
"""
Override to provide custom error handling. Ideally, however,
all errors should be caught at the application level.
"""
if self.debug:
import cgitb
request.stdout.write('Content-Type: text/html\r\n\r\n' +
cgitb.html(sys.exc_info()))
else:
errorpage = """<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>Unhandled Exception</title>
</head><body>
<h1>Unhandled Exception</h1>
<p>An unhandled exception was thrown by the application.</p>
</body></html>
"""
request.stdout.write('Content-Type: text/html\r\n\r\n' +
errorpage)
|