280 lines
8.2 KiB
Python
Executable File
280 lines
8.2 KiB
Python
Executable File
#!/usr/bin/env python3
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# esgd - exceedingly simple gopher daemon
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# Copyright (c) 2021 randomuser/rndusr <randomuser@tilde.club>
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# see LICENSE for license information; README for instructions
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# This program is free software: you can redistribute it and/or
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# modify it under the terms of the GNU Affero General Public
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# License as published by the Free Software Foundation, either
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# version 3 of the License, or (at your option) any later
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# version.
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#
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# This program is distributed in the hope that it will be
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# useful, but WITHOUT ANY WARRANTY; without even the implied
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# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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# PURPOSE. See the GNU General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Affero General
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# Public License along with this program. If not, see
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# <https://www.gnu.org/licenses/>.
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from socketserver import TCPServer
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from socketserver import BaseRequestHandler
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import subprocess
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import argparse
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import os
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import time
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import pwd
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import grp
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class GopherError(BaseException): pass
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class RequestError(GopherError): pass
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class GopherLine:
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def __init__(self, line):
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self.item = "i"
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self.text = ""
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self.location = "null"
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self.host = "null.host"
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self.port = "0"
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self.line = line
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self.parse()
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def parse(self):
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split = self.line.rstrip().split('\t')
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location = False
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if len(split) == 1:
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self.text = split[0]
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return
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try: self.item = split[0][0]
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except IndexError: pass
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try: self.text = split[0][1:]
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except IndexError: pass
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try:
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self.location = split[1]
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location = True
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except IndexError: pass
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try: self.host = split[2]
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except IndexError:
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if location == True: self.host = ghost
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try: self.port = split[3]
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except IndexError:
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if location == True: self.port = str(port)
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def render(self):
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return "{}{}\t{}\t{}\t{}".format(
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self.item,
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self.text,
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self.location,
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self.host,
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self.port
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)
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class Logger:
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def __init__(self, file=None):
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if file != None: self.fd = open(file, "a+")
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else: self.fd = False
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def time(self):
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return int(time.time())
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def write(self, msg):
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if self.fd: self.fd.write("{}\n".format(msg))
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print("{}".format(msg))
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def log(self, msg):
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ct = self.time()
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self.write("[{}] {}".format(str(ct), msg))
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def warn(self, msg):
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ct = self.time()
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self.write("! [{}] {}".format(str(ct), msg))
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def error(self, msg):
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ct = self.time()
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self.write("!! [{}] {}".format(str(ct), msg))
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self.close()
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raise SystemExit
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def close(self):
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if self.fd: self.fd.close()
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class GopherServerLogic:
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def recieveRequest(self):
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data = b""
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while data[-2:] != b"\r\n":
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data += self.request.recv(1)
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decoded = data[:-2].decode("utf-8")
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return decoded
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def requestParser(self, request):
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if ".." in request: raise RequestError
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try:
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if request[0] == "/": request = request[1:]
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except IndexError: pass
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request = request.replace("?", "\t").split("\t")
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try: return (request[0], request[1])
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except IndexError: return (request[0], "")
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def returnRelative(self, file):
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gph = False
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if file == "":
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ret = "gophermap"
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gph = True
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elif os.path.isdir(file):
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if file[-1] != "/": ret = file + "/gophermap"
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else: ret = file + "gophermap"
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gph = True
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elif os.path.isfile(file):
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ret = file
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else: raise RequestError("unreachable state")
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return (ret, gph)
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def fileSendable(self, file):
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return os.access(file, os.F_OK|os.R_OK)
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def fileCGI(self, file):
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if exempt != None:
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for i in exempt:
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if i in file: return False
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if nocgi:
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return False
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return os.access(file, os.F_OK|os.R_OK|os.X_OK)
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def notFound(self):
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self.request.sendall(
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b"3error: file not found!\r\n.\r\n")
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def invalid(self):
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self.request.sendall(
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b"3error: selector contains '..'!\r\n.\r\n")
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def fileToFileArray(self, file):
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fd = open(file, "r")
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ret = [i.rstrip() for i in fd.readlines()]
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fd.close()
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return ret
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def sendFileArray(self, fileArray):
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[self.request.sendall(
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(i.rstrip() + "\r\n").encode("utf-8")
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) for i in fileArray]
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self.request.sendall(b".\r\n")
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def cgi(self, file, query):
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env = {}
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env["QUERY_STRING"] = query
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env["SCRIPT_NAME"] = "/" + file
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env["REMOTE_ADDR"] = self.client_address[0]
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proc = subprocess.Popen(
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[os.getcwd() + "/" + file],
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stdout = subprocess.PIPE,
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env = env
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)
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try: out, err = proc.communicate(timeout=10)
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except TimeoutExpired:
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proc.kill()
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out, err = proc.communicate()
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return out.decode("utf-8")\
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.replace("\r", "")\
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.split("\n")
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def gopherRenderer(self, fileArray):
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gopherlines = []
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for i in fileArray:
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gopherlines.append(GopherLine(i))
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returned = []
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for i in gopherlines:
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returned.append(i.render())
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return returned
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def serveFile(self, file, query, gph):
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if self.fileCGI(file):
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fa = self.cgi(file, query)
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elif self.fileSendable(file):
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fa = self.fileToFileArray(file)
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else:
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log.log("selector not found")
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self.notFound()
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return
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if gph: fa = self.gopherRenderer(fa)
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self.sendFileArray(fa)
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class GopherHandler(BaseRequestHandler,
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GopherServerLogic):
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def handle(self):
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log.log("request from {}".format(
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self.client_address[0]))
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decoded = self.recieveRequest()
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try: parsed = self.requestParser(decoded)
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except RequestError:
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log.log("request was invalid")
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self.invalid()
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return
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try: file = self.returnRelative(parsed[0])
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except RequestError:
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log.log("selector not found")
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self.notFound()
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return
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log.log("serving {}".format(file[0]))
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self.serveFile(file[0], parsed[1], file[1])
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log = Logger()
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def parseArgs():
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parse = argparse.ArgumentParser()
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parse.add_argument("-u", "--user", default="nobody",
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help="user to change to on startup")
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parse.add_argument("-g", "--group", default="nobody",
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help="group to change to on startup")
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parse.add_argument("-s", "--host", default="localhost",
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help="host to host on")
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parse.add_argument("-gs", "--gopherhost", default=None,
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help="host defaulted to in links on gophermaps")
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parse.add_argument("-p", "--port", default=70, type=int,
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help="port to host on")
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parse.add_argument("-d", "--dir", default="/var/gopher",
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help="directory to host from")
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parse.add_argument("-ndx", "--direxc",
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action="append", nargs="*",
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help="make directory-wide exception for file execution")
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parse.add_argument("-nx", "--nocgi", action="store_true",
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help="disable execution of cgi scripts")
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return parse.parse_args()
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if __name__ == "__main__":
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args = parseArgs()
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log.log("arguments parsed")
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switchgrp = grp.getgrnam(args.group).gr_gid
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switchusr = pwd.getpwnam(args.user).pw_uid
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host = args.host
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ghost = args.gopherhost
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port = args.port
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location = args.dir
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exempt = args.direxc
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nocgi = args.nocgi
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log.log("arguments good")
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if ghost == None: ghost = host
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try:
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with TCPServer((host, port), GopherHandler) as server:
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os.setgid(switchgrp)
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os.seteuid(switchusr)
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log.log("switch user successful")
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os.chdir(location)
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log.log("change directory successful")
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server.serve_forever()
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except PermissionError: log.error("invalid permissions")
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except OSError: log.error("address already in use")
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