pywsgi.py

# Copyright (c) 2005-2009, eventlet contributors
# Copyright (c) 2009-2011, gevent contributors

import errno
import sys
import time
import traceback
import mimetools
from datetime import datetime
from urllib import unquote

from gevent import socket
import gevent
from gevent.server import StreamServer
from gevent.hub import GreenletExit


__all__ = ['WSGIHandler', 'WSGIServer']


MAX_REQUEST_LINE = 8192
# Weekday and month names for HTTP date/time formatting; always English!
_WEEKDAYNAME = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
_MONTHNAME = [None,  # Dummy so we can use 1-based month numbers
              "Jan", "Feb", "Mar", "Apr", "May", "Jun",
              "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
_INTERNAL_ERROR_STATUS = '500 Internal Server Error'
_INTERNAL_ERROR_BODY = 'Internal Server Error'
_INTERNAL_ERROR_HEADERS = [('Content-Type', 'text/plain'),
                           ('Connection', 'close'),
                           ('Content-Length', str(len(_INTERNAL_ERROR_BODY)))]
_REQUEST_TOO_LONG_RESPONSE = "HTTP/1.1 414 Request URI Too Long\r\nConnection: close\r\nContent-length: 0\r\n\r\n"
_BAD_REQUEST_RESPONSE = "HTTP/1.1 400 Bad Request\r\nConnection: close\r\nContent-length: 0\r\n\r\n"
_CONTINUE_RESPONSE = "HTTP/1.1 100 Continue\r\n\r\n"


def format_date_time(timestamp):
    year, month, day, hh, mm, ss, wd, _y, _z = time.gmtime(timestamp)
    return "%s, %02d %3s %4d %02d:%02d:%02d GMT" % (_WEEKDAYNAME[wd], day, _MONTHNAME[month], year, hh, mm, ss)


class Input(object):

    def __init__(self, rfile, content_length, socket=None, chunked_input=False):
        self.rfile = rfile
        self.content_length = content_length
        self.socket = socket
        self.position = 0
        self.chunked_input = chunked_input
        self.chunk_length = -1

    def _discard(self):
        if self.socket is None and (self.position < (self.content_length or 0) or self.chunked_input):
            # ## Read and discard body
            while 1:
                d = self.read(16384)
                if not d:
                    break

    def _send_100_continue(self):
        if self.socket is not None:
            self.socket.sendall(_CONTINUE_RESPONSE)
            self.socket = None

    def _do_read(self, length=None, use_readline=False):
        if use_readline:
            reader = self.rfile.readline
        else:
            reader = self.rfile.read
        content_length = self.content_length
        if content_length is None:
            # Either Content-Length or "Transfer-Encoding: chunked" must be present in a request with a body
            # if it was chunked, then this function would have not been called
            return ''
        self._send_100_continue()
        left = content_length - self.position
        if length is None:
            length = left
        elif length > left:
            length = left
        if not length:
            return ''
        read = reader(length)
        self.position += len(read)
        if len(read) < length:
            if (use_readline and not read.endswith("\n")) or not use_readline:
                raise IOError("unexpected end of file while reading request at position %s" % (self.position,))

        return read

    def _chunked_read(self, length=None, use_readline=False):
        rfile = self.rfile
        self._send_100_continue()

        if length == 0:
            return ""

        if length < 0:
            length = None

        if use_readline:
            reader = self.rfile.readline
        else:
            reader = self.rfile.read

        response = []
        while self.chunk_length != 0:
            maxreadlen = self.chunk_length - self.position
            if length is not None and length < maxreadlen:
                maxreadlen = length

            if maxreadlen > 0:
                data = reader(maxreadlen)
                if not data:
                    self.chunk_length = 0
                    raise IOError("unexpected end of file while parsing chunked data")

                datalen = len(data)
                response.append(data)

                self.position += datalen
                if self.chunk_length == self.position:
                    rfile.readline()

                if length is not None:
                    length -= datalen
                    if length == 0:
                        break
                if use_readline and data[-1] == "\n":
                    break
            else:
                line = rfile.readline()
                if not line.endswith("\n"):
                    self.chunk_length = 0
                    raise IOError("unexpected end of file while reading chunked data header")
                self.chunk_length = int(line.split(";", 1)[0], 16)
                self.position = 0
                if self.chunk_length == 0:
                    rfile.readline()
        return ''.join(response)

    def read(self, length=None):
        if self.chunked_input:
            return self._chunked_read(length)
        return self._do_read(length)

    def readline(self, size=None):
        if self.chunked_input:
            return self._chunked_read(size, True)
        else:
            return self._do_read(size, use_readline=True)

    def readlines(self, hint=None):
        return list(self)

    def __iter__(self):
        return self

    def next(self):
        line = self.readline()
        if not line:
            raise StopIteration
        return line


class WSGIHandler(object):
    protocol_version = 'HTTP/1.1'
    MessageClass = mimetools.Message

    def __init__(self, socket, address, server, rfile=None):
        self.socket = socket
        self.client_address = address
        self.server = server
        if rfile is None:
            self.rfile = socket.makefile('rb', -1)
        else:
            self.rfile = rfile

    def handle(self):
        try:
            while self.socket is not None:
                self.time_start = time.time()
                self.time_finish = 0
                result = self.handle_one_request()
                if result is None:
                    break
                if result is True:
                    continue
                self.status, response_body = result
                self.socket.sendall(response_body)
                if self.time_finish == 0:
                    self.time_finish = time.time()
                self.log_request()
                break
        finally:
            if self.socket is not None:
                try:
                    self.socket._sock.close()  # do not rely on garbage collection
                    self.socket.close()
                except socket.error:
                    pass
            self.__dict__.pop('socket', None)
            self.__dict__.pop('rfile', None)

    def _check_http_version(self):
        version = self.request_version
        if not version.startswith("HTTP/"):
            return False
        version = tuple(int(x) for x in version[5:].split("."))  # "HTTP/"
        if version[1] < 0 or version < (0, 9) or version >= (2, 0):
            return False
        return True

    def read_request(self, raw_requestline):
        self.requestline = raw_requestline.rstrip()
        words = self.requestline.split()
        if len(words) == 3:
            self.command, self.path, self.request_version = words
            if not self._check_http_version():
                self.log_error('Invalid http version: %r', raw_requestline)
                return
        elif len(words) == 2:
            self.command, self.path = words
            if self.command != "GET":
                self.log_error('Expected GET method: %r', raw_requestline)
                return
            self.request_version = "HTTP/0.9"
            # QQQ I'm pretty sure we can drop support for HTTP/0.9
        else:
            self.log_error('Invalid HTTP method: %r', raw_requestline)
            return

        self.headers = self.MessageClass(self.rfile, 0)
        if self.headers.status:
            self.log_error('Invalid headers status: %r', self.headers.status)
            return

        if self.headers.get("transfer-encoding", "").lower() == "chunked":
            try:
                del self.headers["content-length"]
            except KeyError:
                pass

        content_length = self.headers.get("content-length")
        if content_length is not None:
            content_length = int(content_length)
            if content_length < 0:
                self.log_error('Invalid Content-Length: %r', content_length)
                return
            if content_length and self.command in ('GET', 'HEAD'):
                self.log_error('Unexpected Content-Length')
                return

        self.content_length = content_length

        if self.request_version == "HTTP/1.1":
            conntype = self.headers.get("Connection", "").lower()
            if conntype == "close":
                self.close_connection = True
            else:
                self.close_connection = False
        else:
            self.close_connection = True

        return True

    def log_error(self, msg, *args):
        try:
            message = msg % args
        except Exception:
            traceback.print_exc()
            message = '%r %r' % (msg, args)
        try:
            message = '%s: %s' % (self.socket, message)
        except Exception:
            pass
        try:
            sys.stderr.write(message + '\n')
        except Exception:
            traceback.print_exc()

    def read_requestline(self):
        return self.rfile.readline(MAX_REQUEST_LINE)

    def handle_one_request(self):
        if self.rfile.closed:
            return

        try:
            raw_requestline = self.read_requestline()
        except socket.error:
            # "Connection reset by peer" or other socket errors aren't interesting here
            return

        if not raw_requestline:
            return

        self.response_length = 0

        if len(raw_requestline) >= MAX_REQUEST_LINE:
            return ('414', _REQUEST_TOO_LONG_RESPONSE)

        try:
            if not self.read_request(raw_requestline):
                return ('400', _BAD_REQUEST_RESPONSE)
        except Exception:
            ex = sys.exc_info()[1]
            if not isinstance(ex, ValueError):
                traceback.print_exc()
            self.log_error('Invalid request: %s', str(ex) or ex.__class__.__name__)
            return ('400', _BAD_REQUEST_RESPONSE)

        self.environ = self.get_environ()
        self.application = self.server.application
        try:
            self.handle_one_response()
        except socket.error:
            ex = sys.exc_info()[1]
            # Broken pipe, connection reset by peer
            if ex.args[0] in (errno.EPIPE, errno.ECONNRESET):
                sys.exc_clear()
                return
            else:
                raise

        if self.close_connection:
            return

        if self.rfile.closed:
            return

        return True  # read more requests

    def finalize_headers(self):
    
        self.response_headers = list(self.response_headers)
        if self.provided_date is None:
            self.response_headers.append(('Date', format_date_time(time.time())))

        if self.code not in (304, 204):
            # the reply will include message-body; make sure we have either Content-Length or chunked
            if self.provided_content_length is None:
                if hasattr(self.result, '__len__'):
                    self.response_headers.append(('Content-Length', str(sum(len(chunk) for chunk in self.result))))
                else:
                    if self.request_version != 'HTTP/1.0':
                        self.response_use_chunked = True
                        self.response_headers.append(('Transfer-Encoding', 'chunked'))

    def write(self, data):
        towrite = []
        if not self.status:
            raise AssertionError("The application did not call start_response()")
        if not self.headers_sent:
            self.headers_sent = True
            self.finalize_headers()

            towrite.append('%s %s\r\n' % ('HTTP/1.1', self.status))
            for header in self.response_headers:
                towrite.append('%s: %s\r\n' % header)

            towrite.append('\r\n')

        if data:
            if self.code in (304, 204):
                raise AssertionError('The %s response must have no body' % self.code)

            if self.response_use_chunked:
                ## Write the chunked encoding
                towrite.append("%x\r\n%s\r\n" % (len(data), data))
            else:
                towrite.append(data)

        msg = ''.join(towrite)
        try:
            self.socket.sendall(msg)
        except socket.error, ex:
            self.status = 'socket error: %s' % ex
            if self.code > 0:
                self.code = -self.code
            raise
        self.response_length += len(msg)

    def start_response(self, status, headers, exc_info=None):
        if exc_info:
            try:
                if self.headers_sent:
                    # Re-raise original exception if headers sent
                    raise exc_info[0], exc_info[1], exc_info[2]
            finally:
                # Avoid dangling circular ref
                exc_info = None
        self.code = int(status.split(' ', 1)[0])
        self.status = status
        self.response_headers = headers

        provided_connection = None
        self.provided_date = None
        self.provided_content_length = None

        
        self.response_headers = list(self.response_headers)

        for header, value in headers:
            header = header.lower()
            if header == 'connection':
                provided_connection = value
            elif header == 'date':
                self.provided_date = value
            elif header == 'content-length':
                self.provided_content_length = value

        if self.request_version == 'HTTP/1.0' and provided_connection is None:
            headers.append(('Connection', 'close'))
            self.close_connection = True
        elif provided_connection == 'close':
            self.close_connection = True

        if self.code in (304, 204):
            if self.provided_content_length is not None and self.provided_content_length != '0':
                msg = 'Invalid Content-Length for %s response: %r (must be absent or zero)' % (self.code, self.provided_content_length)
                raise AssertionError(msg)

        return self.write

    def log_request(self):
        log = self.server.log
        if log:
            log.write(self.format_request() + '\n')

    def format_request(self):
        now = datetime.now().replace(microsecond=0)
        if self.time_finish:
            delta = '%.6f' % (self.time_finish - self.time_start)
            length = self.response_length
        else:
            delta = '-'
            if not self.response_length:
                length = '-'
        return '%s - - [%s] "%s" %s %s %s' % (
            self.client_address[0],
            now,
            self.requestline,
            (getattr(self, 'status', None) or '000').split()[0],
            length,
            delta)

    def process_result(self):
        for data in self.result:
            if data:
                self.write(data)
        if self.status and not self.headers_sent:
            self.write('')
        if self.response_use_chunked:
            self.socket.sendall('0\r\n\r\n')
            self.response_length += 5

    def run_application(self):
        self.result = self.application(self.environ, self.start_response)
        self.process_result()

    def handle_one_response(self):
        self.time_start = time.time()
        self.status = None
        self.headers_sent = False

        self.result = None
        self.response_use_chunked = False
        self.response_length = 0

        try:
            try:
                self.run_application()
            finally:
                close = getattr(self.result, 'close', None)
                if close is not None:
                    close()
                self.wsgi_input._discard()
        except:
            self.handle_error(*sys.exc_info())
        finally:
            self.time_finish = time.time()
            self.log_request()

    def handle_error(self, type, value, tb):
        if not issubclass(type, GreenletExit):
            self.server.loop.handle_error(self.environ, type, value, tb)
        del tb
        if self.response_length:
            self.close_connection = True
        else:
            self.start_response(_INTERNAL_ERROR_STATUS, _INTERNAL_ERROR_HEADERS)
            self.write(_INTERNAL_ERROR_BODY)

    def get_environ(self):
        env = self.server.get_environ()
        env['REQUEST_METHOD'] = self.command
        env['SCRIPT_NAME'] = ''

        if '?' in self.path:
            path, query = self.path.split('?', 1)
        else:
            path, query = self.path, ''
        env['PATH_INFO'] = unquote(path)
        env['QUERY_STRING'] = query

        if self.headers.typeheader is not None:
            env['CONTENT_TYPE'] = self.headers.typeheader

        length = self.headers.getheader('content-length')
        if length:
            env['CONTENT_LENGTH'] = length
        env['SERVER_PROTOCOL'] = 'HTTP/1.1'

        client_address = self.client_address
        if isinstance(client_address, tuple):
            env['REMOTE_ADDR'] = str(client_address[0])
            env['REMOTE_PORT'] = str(client_address[1])

        for header in self.headers.headers:
            key, value = header.split(':', 1)
            key = key.replace('-', '_').upper()
            if key not in ('CONTENT_TYPE', 'CONTENT_LENGTH'):
                value = value.strip()
                key = 'HTTP_' + key
                if key in env:
                    if 'COOKIE' in key:
                        env[key] += '; ' + value
                    else:
                        env[key] += ',' + value
                else:
                    env[key] = value

        if env.get('HTTP_EXPECT') == '100-continue':
            socket = self.socket
        else:
            socket = None
        chunked = env.get('HTTP_TRANSFER_ENCODING', '').lower() == 'chunked'
        self.wsgi_input = Input(self.rfile, self.content_length, socket=socket, chunked_input=chunked)
        env['wsgi.input'] = self.wsgi_input
        return env


class WSGIServer(StreamServer):
    """A WSGI server based on :class:`StreamServer` that supports HTTPS."""

    handler_class = WSGIHandler
    base_env = {'GATEWAY_INTERFACE': 'CGI/1.1',
                'SERVER_SOFTWARE': 'gevent/%d.%d Python/%d.%d' % (gevent.version_info[:2] + sys.version_info[:2]),
                'SCRIPT_NAME': '',
                'wsgi.version': (1, 0),
                'wsgi.multithread': False,
                'wsgi.multiprocess': False,
                'wsgi.run_once': False}

    def __init__(self, listener, application=None, backlog=None, spawn='default', log='default', handler_class=None,
                 environ=None, **ssl_args):
        StreamServer.__init__(self, listener, backlog=backlog, spawn=spawn, **ssl_args)
        if application is not None:
            self.application = application
        if handler_class is not None:
            self.handler_class = handler_class
        if log == 'default':
            self.log = sys.stderr
        else:
            self.log = log
        self.set_environ(environ)
        self.set_max_accept()

    def set_environ(self, environ=None):
        if environ is not None:
            self.environ = environ
        environ_update = getattr(self, 'environ', None)
        self.environ = self.base_env.copy()
        if self.ssl_enabled:
            self.environ['wsgi.url_scheme'] = 'https'
        else:
            self.environ['wsgi.url_scheme'] = 'http'
        if environ_update is not None:
            self.environ.update(environ_update)
        if self.environ.get('wsgi.errors') is None:
            self.environ['wsgi.errors'] = sys.stderr

    def set_max_accept(self):
        if self.environ.get('wsgi.multiprocess'):
            self.max_accept = 1

    def get_environ(self):
        return self.environ.copy()

    def init_socket(self):
        StreamServer.init_socket(self)
        self.update_environ()

    def update_environ(self):
        address = self.address
        if isinstance(address, tuple):
            if 'SERVER_NAME' not in self.environ:
                try:
                    name = socket.getfqdn(address[0])
                except socket.error:
                    name = str(address[0])
                self.environ['SERVER_NAME'] = name
            self.environ.setdefault('SERVER_PORT', str(address[1]))
        else:
            self.environ.setdefault('SERVER_NAME', '')
            self.environ.setdefault('SERVER_PORT', '')

    def handle(self, socket, address):
        handler = self.handler_class(socket, address, self)
        handler.handle()