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# -*- test-case-name: twisted.web.test.test_cgi -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
I hold resource classes and helper classes that deal with CGI scripts.
"""
# System Imports
import os
import urllib
from typing import AnyStr
# Twisted Imports
from twisted.internet import protocol
from twisted.logger import Logger
from twisted.python import filepath
from twisted.spread import pb
from twisted.web import http, resource, server, static
class CGIDirectory(resource.Resource, filepath.FilePath[AnyStr]):
def __init__(self, pathname):
resource.Resource.__init__(self)
filepath.FilePath.__init__(self, pathname)
def getChild(self, path, request):
fnp = self.child(path)
if not fnp.exists():
return static.File.childNotFound
elif fnp.isdir():
return CGIDirectory(fnp.path)
else:
return CGIScript(fnp.path)
def render(self, request):
notFound = resource.NoResource(
"CGI directories do not support directory listing."
)
return notFound.render(request)
class CGIScript(resource.Resource):
"""
L{CGIScript} is a resource which runs child processes according to the CGI
specification.
The implementation is complex due to the fact that it requires asynchronous
IPC with an external process with an unpleasant protocol.
"""
isLeaf = 1
def __init__(self, filename, registry=None, reactor=None):
"""
Initialize, with the name of a CGI script file.
"""
self.filename = filename
if reactor is None:
# This installs a default reactor, if None was installed before.
# We do a late import here, so that importing the current module
# won't directly trigger installing a default reactor.
from twisted.internet import reactor
self._reactor = reactor
def render(self, request):
"""
Do various things to conform to the CGI specification.
I will set up the usual slew of environment variables, then spin off a
process.
@type request: L{twisted.web.http.Request}
@param request: An HTTP request.
"""
scriptName = b"/" + b"/".join(request.prepath)
serverName = request.getRequestHostname().split(b":")[0]
env = {
"SERVER_SOFTWARE": server.version,
"SERVER_NAME": serverName,
"GATEWAY_INTERFACE": "CGI/1.1",
"SERVER_PROTOCOL": request.clientproto,
"SERVER_PORT": str(request.getHost().port),
"REQUEST_METHOD": request.method,
"SCRIPT_NAME": scriptName,
"SCRIPT_FILENAME": self.filename,
"REQUEST_URI": request.uri,
}
ip = request.getClientAddress().host
if ip is not None:
env["REMOTE_ADDR"] = ip
pp = request.postpath
if pp:
env["PATH_INFO"] = "/" + "/".join(pp)
if hasattr(request, "content"):
# 'request.content' is either a StringIO or a TemporaryFile, and
# the file pointer is sitting at the beginning (seek(0,0))
request.content.seek(0, 2)
length = request.content.tell()
request.content.seek(0, 0)
env["CONTENT_LENGTH"] = str(length)
try:
qindex = request.uri.index(b"?")
except ValueError:
env["QUERY_STRING"] = ""
qargs = []
else:
qs = env["QUERY_STRING"] = request.uri[qindex + 1 :]
if b"=" in qs:
qargs = []
else:
qargs = [urllib.parse.unquote(x.decode()) for x in qs.split(b"+")]
# Propagate HTTP headers
for title, header in request.getAllHeaders().items():
envname = title.replace(b"-", b"_").upper()
if title not in (b"content-type", b"content-length", b"proxy"):
envname = b"HTTP_" + envname
env[envname] = header
# Propagate our environment
for key, value in os.environ.items():
if key not in env:
env[key] = value
# And they're off!
self.runProcess(env, request, qargs)
return server.NOT_DONE_YET
def runProcess(self, env, request, qargs=[]):
"""
Run the cgi script.
@type env: A L{dict} of L{str}, or L{None}
@param env: The environment variables to pass to the process that will
get spawned. See
L{twisted.internet.interfaces.IReactorProcess.spawnProcess} for
more information about environments and process creation.
@type request: L{twisted.web.http.Request}
@param request: An HTTP request.
@type qargs: A L{list} of L{str}
@param qargs: The command line arguments to pass to the process that
will get spawned.
"""
p = CGIProcessProtocol(request)
self._reactor.spawnProcess(
p,
self.filename,
[self.filename] + qargs,
env,
os.path.dirname(self.filename),
)
class FilteredScript(CGIScript):
"""
I am a special version of a CGI script, that uses a specific executable.
This is useful for interfacing with other scripting languages that adhere
to the CGI standard. My C{filter} attribute specifies what executable to
run, and my C{filename} init parameter describes which script to pass to
the first argument of that script.
To customize me for a particular location of a CGI interpreter, override
C{filter}.
@type filter: L{str}
@ivar filter: The absolute path to the executable.
"""
filter = "/usr/bin/cat"
def runProcess(self, env, request, qargs=[]):
"""
Run a script through the C{filter} executable.
@type env: A L{dict} of L{str}, or L{None}
@param env: The environment variables to pass to the process that will
get spawned. See
L{twisted.internet.interfaces.IReactorProcess.spawnProcess}
for more information about environments and process creation.
@type request: L{twisted.web.http.Request}
@param request: An HTTP request.
@type qargs: A L{list} of L{str}
@param qargs: The command line arguments to pass to the process that
will get spawned.
"""
p = CGIProcessProtocol(request)
self._reactor.spawnProcess(
p,
self.filter,
[self.filter, self.filename] + qargs,
env,
os.path.dirname(self.filename),
)
class CGIProcessProtocol(protocol.ProcessProtocol, pb.Viewable):
handling_headers = 1
headers_written = 0
headertext = b""
errortext = b""
_log = Logger()
_requestFinished = False
# Remotely relay producer interface.
def view_resumeProducing(self, issuer):
self.resumeProducing()
def view_pauseProducing(self, issuer):
self.pauseProducing()
def view_stopProducing(self, issuer):
self.stopProducing()
def resumeProducing(self):
self.transport.resumeProducing()
def pauseProducing(self):
self.transport.pauseProducing()
def stopProducing(self):
self.transport.loseConnection()
def __init__(self, request):
self.request = request
self.request.notifyFinish().addBoth(self._finished)
def connectionMade(self):
self.request.registerProducer(self, 1)
self.request.content.seek(0, 0)
content = self.request.content.read()
if content:
self.transport.write(content)
self.transport.closeStdin()
def errReceived(self, error):
self.errortext = self.errortext + error
def outReceived(self, output):
"""
Handle a chunk of input
"""
# First, make sure that the headers from the script are sorted
# out (we'll want to do some parsing on these later.)
if self.handling_headers:
text = self.headertext + output
headerEnds = []
for delimiter in b"\n\n", b"\r\n\r\n", b"\r\r", b"\n\r\n":
headerend = text.find(delimiter)
if headerend != -1:
headerEnds.append((headerend, delimiter))
if headerEnds:
# The script is entirely in control of response headers;
# disable the default Content-Type value normally provided by
# twisted.web.server.Request.
self.request.defaultContentType = None
headerEnds.sort()
headerend, delimiter = headerEnds[0]
self.headertext = text[:headerend]
# This is a final version of the header text.
linebreak = delimiter[: len(delimiter) // 2]
headers = self.headertext.split(linebreak)
for header in headers:
br = header.find(b": ")
if br == -1:
self._log.error(
"ignoring malformed CGI header: {header!r}", header=header
)
else:
headerName = header[:br].lower()
headerText = header[br + 2 :]
if headerName == b"location":
self.request.setResponseCode(http.FOUND)
if headerName == b"status":
try:
# "XXX <description>" sometimes happens.
statusNum = int(headerText[:3])
except BaseException:
self._log.error("malformed status header")
else:
self.request.setResponseCode(statusNum)
else:
# Don't allow the application to control
# these required headers.
if headerName.lower() not in (b"server", b"date"):
self.request.responseHeaders.addRawHeader(
headerName, headerText
)
output = text[headerend + len(delimiter) :]
self.handling_headers = 0
if self.handling_headers:
self.headertext = text
if not self.handling_headers:
self.request.write(output)
def processEnded(self, reason):
if reason.value.exitCode != 0:
self._log.error(
"CGI {uri} exited with exit code {exitCode}",
uri=self.request.uri,
exitCode=reason.value.exitCode,
)
if self.errortext:
self._log.error(
"Errors from CGI {uri}: {errorText}",
uri=self.request.uri,
errorText=self.errortext,
)
if self.handling_headers:
self._log.error(
"Premature end of headers in {uri}: {headerText}",
uri=self.request.uri,
headerText=self.headertext,
)
if not self._requestFinished:
self.request.write(
resource.ErrorPage(
http.INTERNAL_SERVER_ERROR,
"CGI Script Error",
"Premature end of script headers.",
).render(self.request)
)
if not self._requestFinished:
self.request.unregisterProducer()
self.request.finish()
def _finished(self, ignored):
"""
Record the end of the response generation for the request being
serviced.
"""
self._requestFinished = True