#!/usr/bin/python

"""Tiny HTTP Proxy.

This module implements GET, HEAD, POST, PUT and DELETE methods
on BaseHTTPServer, and behaves as an HTTP proxy.  The CONNECT
method is also implemented experimentally, but has not been
tested yet.

Any help will be greatly appreciated.       SUZUKI Hisao

2009/11/23 - Modified by Mitko Haralanov
             * Added very simple FTP file retrieval
             * Added custom logging methods
             * Added code to make this a standalone application
"""

import ftplib
import getopt
import logging
import logging.handlers
import os
import select
import signal
import socket
import sys
import threading
from six import PY3
from types import FrameType, CodeType
from time import sleep

from caldav.lib.python_utilities import to_wire, to_local

if PY3:
    from urllib import parse
    from urllib.parse import urlparse, urlunparse
    from http.server import BaseHTTPRequestHandler, HTTPServer
    from socketserver import ThreadingMixIn
else:
    from urlparse import urlparse as parse
    from urlparse import urlparse, urlunparse
    from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
    from SocketServer import ThreadingMixIn

__version__ = "0.3.1"

DEFAULT_LOG_FILENAME = "proxy.log"


class ProxyHandler (BaseHTTPRequestHandler):
    __base = BaseHTTPRequestHandler
    __base_handle = __base.handle

    server_version = "TinyHTTPProxy/" + __version__
    rbufsize = 0                        # self.rfile Be unbuffered

    def handle(self):
        (ip, port) = self.client_address
        self.server.logger.log(logging.INFO, "Request from '%s'", ip)
        if hasattr(self, 'allowed_clients') and ip not in self.allowed_clients:
            self.raw_requestline = self.rfile.readline()
            if self.parse_request():
                self.send_error(403)
        else:
            self.__base_handle()

    def _connect_to(self, netloc, soc):
        i = netloc.find(':')
        if i >= 0:
            host_port = netloc[:i], int(netloc[i + 1:])
        else:
            host_port = netloc, 80
        self.server.logger.log(
            logging.INFO, "connect to %s:%d", host_port[0], host_port[1])
        try:
            soc.connect(host_port)
        except socket.error as arg:
            try:
                msg = arg[1]
            except:
                msg = arg
            self.send_error(404, msg)
            return 0
        return 1

    def do_CONNECT(self):
        soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        try:
            if self._connect_to(self.path, soc):
                self.log_request(200)
                self.wfile.write(self.protocol_version +
                                 " 200 Connection established\r\n")
                self.wfile.write("Proxy-agent: %s\r\n" % self.version_string())
                self.wfile.write("\r\n")
                self._read_write(soc, 300)
        finally:
            soc.close()
            self.connection.close()

    def do_GET(self):
        (scm, netloc, path, params, query, fragment) = urlparse(
            self.path, 'http')
        if scm not in ('http', 'ftp') or fragment or not netloc:
            self.send_error(400, "bad url %s" % self.path)
            return
        soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        try:
            if scm == 'http':
                if self._connect_to(netloc, soc):
                    self.log_request()
                    soc.send(to_wire("%s %s %s\r\n" % (
                        self.command,
                        urlunparse(('', '', path, params, query, '')),
                        self.request_version)))
                    self.headers['Connection'] = 'close'
                    del self.headers['Proxy-Connection']
                    for key_val in list(self.headers.items()):
                        soc.send(to_wire("%s: %s\r\n" % key_val))
                    soc.send(to_wire("\r\n"))
                    self._read_write(soc)
            elif scm == 'ftp':
                # fish out user and password information
                i = netloc.find('@')
                if i >= 0:
                    login_info, netloc = netloc[:i], netloc[i + 1:]
                    try:
                        user, passwd = login_info.split(':', 1)
                    except ValueError:
                        user, passwd = "anonymous", None
                else:
                    user, passwd = "anonymous", None
                self.log_request()
                try:
                    ftp = ftplib.FTP(netloc)
                    ftp.login(user, passwd)
                    if self.command == "GET":
                        ftp.retrbinary("RETR %s" % path, self.connection.send)
                    ftp.quit()
                except Exception as e:
                    self.server.logger.log(
                        logging.WARNING, "FTP Exception: %s", e)
        finally:
            soc.close()
            self.connection.close()

    def _read_write(self, soc, max_idling=20, local=False):
        iw = [self.connection, soc]
        local_data = ""
        ow = []
        count = 0
        while 1:
            count += 1
            (ins, _, exs) = select.select(iw, ow, iw, 1)
            if exs:
                break
            if ins:
                for i in ins:
                    if i is soc:
                        out = self.connection
                    else:
                        out = soc
                    data = i.recv(8192)
                    if data:
                        if local:
                            local_data += data
                        else:
                            out.send(data)
                        count = 0
            if count == max_idling:
                break
        if local:
            return to_local(local_data)
        return None

    do_HEAD = do_GET
    do_POST = do_GET
    do_PUT = do_GET
    do_DELETE = do_GET
    do_PROPFIND = do_GET

    def log_message(self, format, *args):
        self.server.logger.log(
            logging.INFO, "%s %s", self.address_string(), format % args)

    def log_error(self, format, *args):
        self.server.logger.log(
            logging.ERROR, "%s %s", self.address_string(), format % args)


class ThreadingHTTPServer(ThreadingMixIn, HTTPServer):
    def __init__(self, server_address, RequestHandlerClass, logger=None):
        HTTPServer.__init__(self, server_address, RequestHandlerClass)
        self.logger = logger


class NonThreadingHTTPServer(HTTPServer):
    def __init__(self, server_address, RequestHandlerClass, logger=None):
        HTTPServer.__init__(self, server_address, RequestHandlerClass)
        self.logger = logger


def logSetup(filename, log_size, daemon):
    logger = logging.getLogger("TinyHTTPProxy")
    logger.setLevel(logging.INFO)
    if not filename:
        if not daemon:
            # display to the screen
            handler = logging.StreamHandler()
        else:
            handler = logging.handlers.RotatingFileHandler(
                DEFAULT_LOG_FILENAME, maxBytes=(log_size * (1 << 20)),
                backupCount=5)
    else:
        handler = logging.handlers.RotatingFileHandler(
            filename, maxBytes=(log_size * (1 << 20)), backupCount=5)
    fmt = logging.Formatter("[%(asctime)-12s.%(msecs)03d] "
                            "%(levelname)-8s {%(name)s %(threadName)s}"
                            " %(message)s",
                            "%Y-%m-%d %H:%M:%S")
    handler.setFormatter(fmt)

    logger.addHandler(handler)
    return logger


def usage(msg=None):
    if msg:
        print(msg)
    print(sys.argv[0],
          "[-p port] [-l logfile] [-dh] [allowed_client_name ...]]")
    print()
    print("   -p       - Port to bind to")
    print("   -l       - Path to logfile. If not specified, STDOUT is used")
    print("   -d       - Run in the background")
    print()


def handler(signo, frame):
    while frame and isinstance(frame, FrameType):
        if frame.f_code and isinstance(frame.f_code, CodeType):
            if "run_event" in frame.f_code.co_varnames:
                frame.f_locals["run_event"].set()
                return
        frame = frame.f_back


def daemonize(logger):
    class DevNull(object):
        def __init__(self): self.fd = os.open("/dev/null", os.O_WRONLY)
        def write(self, *args, **kwargs): return 0
        def read(self, *args, **kwargs): return 0
        def fileno(self): return self.fd
        def close(self): os.close(self.fd)
    class ErrorLog:
        def __init__(self, obj): self.obj = obj
        def write(self, string): self.obj.log(logging.ERROR, string)
        def read(self, *args, **kwargs): return 0
        def close(self): pass

    if os.fork() != 0:
        # allow the child pid to instanciate the server
        # class
        sleep(1)
        sys.exit(0)
    os.setsid()
    fd = os.open('/dev/null', os.O_RDONLY)
    if fd != 0:
        os.dup2(fd, 0)
        os.close(fd)
    null = DevNull()
    log = ErrorLog(logger)
    sys.stdout = null
    sys.stderr = log
    sys.stdin = null
    fd = os.open('/dev/null', os.O_WRONLY)
    # if fd != 1: os.dup2(fd, 1)
    os.dup2(sys.stdout.fileno(), 1)
    if fd != 2:
        os.dup2(fd, 2)
    if fd not in (1, 2):
        os.close(fd)


def main():
    logfile = None
    daemon = False
    max_log_size = 20
    port = 8080
    allowed = []
    run_event = threading.Event()
    local_hostname = socket.gethostname()

    try:
        opts, args = getopt.getopt(sys.argv[1:], "l:dhp:", [])
    except getopt.GetoptError as e:
        usage(str(e))
        return 1

    for opt, value in opts:
        if opt == "-p": port = int(value)
        if opt == "-l": logfile = value
        if opt == "-d": daemon = not daemon
        if opt == "-h":
            usage()
            return 0

    # setup the log file
    logger = logSetup(logfile, max_log_size, daemon)

    if daemon:
        daemonize(logger)
    signal.signal(signal.SIGINT, handler)

    if args:
        allowed = []
        for name in args:
            client = socket.gethostbyname(name)
            allowed.append(client)
            logger.log(logging.INFO, "Accept: %s (%s)" % (client, name))
        ProxyHandler.allowed_clients = allowed
    else:
        logger.log(logging.INFO, "Any clients will be served...")

    server_address = (socket.gethostbyname(local_hostname), port)
    ProxyHandler.protocol = "HTTP/1.0"
    httpd = ThreadingHTTPServer(server_address, ProxyHandler, logger)
    sa = httpd.socket.getsockname()
    print("Servering HTTP on", sa[0], "port", sa[1])
    req_count = 0
    while not run_event.isSet():
        try:
            httpd.handle_request()
            req_count += 1
            if req_count == 1000:
                logger.log(logging.INFO, "Number of active threads: %s",
                           threading.activeCount())
                req_count = 0
        except select.error as e:
            if e[0] == 4 and run_event.isSet():
                pass
            else:
                logger.log(logging.CRITICAL, "Errno: %d - %s", e[0], e[1])
    logger.log(logging.INFO, "Server shutdown")
    return 0

if __name__ == '__main__':
    sys.exit(main())