Python socket/socketserver 源码

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Socket源码

Cpython版本：v3.7.5

 

socket.py

# Wrapper module for _socket, providing some additional facilities
# implemented in Python.

"""\
This module provides socket operations and some related functions.
On Unix, it supports IP (Internet Protocol) and Unix domain sockets.
On other systems, it only supports IP. Functions specific for a
socket are available as methods of the socket object.

Functions:

socket() -- create a new socket object
socketpair() -- create a pair of new socket objects [*]
fromfd() -- create a socket object from an open file descriptor [*]
fromshare() -- create a socket object from data received from socket.share() [*]
gethostname() -- return the current hostname
gethostbyname() -- map a hostname to its IP number
gethostbyaddr() -- map an IP number or hostname to DNS info
getservbyname() -- map a service name and a protocol name to a port number
getprotobyname() -- map a protocol name (e.g. 'tcp') to a number
ntohs(), ntohl() -- convert 16, 32 bit int from network to host byte order
htons(), htonl() -- convert 16, 32 bit int from host to network byte order
inet_aton() -- convert IP addr string (123.45.67.89) to 32-bit packed format
inet_ntoa() -- convert 32-bit packed format IP to string (123.45.67.89)
socket.getdefaulttimeout() -- get the default timeout value
socket.setdefaulttimeout() -- set the default timeout value
create_connection() -- connects to an address, with an optional timeout and
                       optional source address.

 [*] not available on all platforms!

Special objects:

SocketType -- type object for socket objects
error -- exception raised for I/O errors
has_ipv6 -- boolean value indicating if IPv6 is supported

IntEnum constants:

AF_INET, AF_UNIX -- socket domains (first argument to socket() call)
SOCK_STREAM, SOCK_DGRAM, SOCK_RAW -- socket types (second argument)

Integer constants:

Many other constants may be defined; these may be used in calls to
the setsockopt() and getsockopt() methods.
"""

import _socket
from _socket import *

import os, sys, io, selectors
from enum import IntEnum, IntFlag

try:
    import errno
except ImportError:
    errno = None
EBADF = getattr(errno, 'EBADF', 9)
EAGAIN = getattr(errno, 'EAGAIN', 11)
EWOULDBLOCK = getattr(errno, 'EWOULDBLOCK', 11)

__all__ = ["fromfd", "getfqdn", "create_connection",
        "AddressFamily", "SocketKind"]
__all__.extend(os._get_exports_list(_socket))

# Set up the socket.AF_* socket.SOCK_* constants as members of IntEnums for
# nicer string representations.
# Note that _socket only knows about the integer values. The public interface
# in this module understands the enums and translates them back from integers
# where needed (e.g. .family property of a socket object).

IntEnum._convert(
        'AddressFamily',
        __name__,
        lambda C: C.isupper() and C.startswith('AF_'))

IntEnum._convert(
        'SocketKind',
        __name__,
        lambda C: C.isupper() and C.startswith('SOCK_'))

IntFlag._convert(
        'MsgFlag',
        __name__,
        lambda C: C.isupper() and C.startswith('MSG_'))

IntFlag._convert(
        'AddressInfo',
        __name__,
        lambda C: C.isupper() and C.startswith('AI_'))

_LOCALHOST    = '127.0.0.1'
_LOCALHOST_V6 = '::1'


def _intenum_converter(value, enum_klass):
    """Convert a numeric family value to an IntEnum member.

    If it's not a known member, return the numeric value itself.
    """
    try:
        return enum_klass(value)
    except ValueError:
        return value

_realsocket = socket

# WSA error codes
if sys.platform.lower().startswith("win"):
    errorTab = {}
    errorTab[10004] = "The operation was interrupted."
    errorTab[10009] = "A bad file handle was passed."
    errorTab[10013] = "Permission denied."
    errorTab[10014] = "A fault occurred on the network??" # WSAEFAULT
    errorTab[10022] = "An invalid operation was attempted."
    errorTab[10035] = "The socket operation would block"
    errorTab[10036] = "A blocking operation is already in progress."
    errorTab[10048] = "The network address is in use."
    errorTab[10054] = "The connection has been reset."
    errorTab[10058] = "The network has been shut down."
    errorTab[10060] = "The operation timed out."
    errorTab[10061] = "Connection refused."
    errorTab[10063] = "The name is too long."
    errorTab[10064] = "The host is down."
    errorTab[10065] = "The host is unreachable."
    __all__.append("errorTab")


class _GiveupOnSendfile(Exception): pass


class socket(_socket.socket):

    """A subclass of _socket.socket adding the makefile() method."""

    __slots__ = ["__weakref__", "_io_refs", "_closed"]

    def __init__(self, family=-1, type=-1, proto=-1, fileno=None):
        # For user code address family and type values are IntEnum members, but
        # for the underlying _socket.socket they're just integers. The
        # constructor of _socket.socket converts the given argument to an
        # integer automatically.
        if fileno is None:
            if family == -1:
                family = AF_INET
            if type == -1:
                type = SOCK_STREAM
            if proto == -1:
                proto = 0
        _socket.socket.__init__(self, family, type, proto, fileno)
        self._io_refs = 0
        self._closed = False

    def __enter__(self):
        return self

    def __exit__(self, *args):
        if not self._closed:
            self.close()

    def __repr__(self):
        """Wrap __repr__() to reveal the real class name and socket
        address(es).
        """
        closed = getattr(self, '_closed', False)
        s = "<%s.%s%s fd=%i, family=%s, type=%s, proto=%i" \
            % (self.__class__.__module__,
               self.__class__.__qualname__,
               " [closed]" if closed else "",
               self.fileno(),
               self.family,
               self.type,
               self.proto)
        if not closed:
            try:
                laddr = self.getsockname()
                if laddr:
                    s += ", laddr=%s" % str(laddr)
            except error:
                pass
            try:
                raddr = self.getpeername()
                if raddr:
                    s += ", raddr=%s" % str(raddr)
            except error:
                pass
        s += '>'
        return s

    def __getstate__(self):
        raise TypeError("Cannot serialize socket object")

    def dup(self):
        """dup() -> socket object

        Duplicate the socket. Return a new socket object connected to the same
        system resource. The new socket is non-inheritable.
        """
        fd = dup(self.fileno())
        sock = self.__class__(self.family, self.type, self.proto, fileno=fd)
        sock.settimeout(self.gettimeout())
        return sock

    def accept(self):
        """accept() -> (socket object, address info)

        Wait for an incoming connection.  Return a new socket
        representing the connection, and the address of the client.
        For IP sockets, the address info is a pair (hostaddr, port).
        """
        fd, addr = self._accept()
        sock = socket(self.family, self.type, self.proto, fileno=fd)
        # Issue #7995: if no default timeout is set and the listening
        # socket had a (non-zero) timeout, force the new socket in blocking
        # mode to override platform-specific socket flags inheritance.
        if getdefaulttimeout() is None and self.gettimeout():
            sock.setblocking(True)
        return sock, addr

    def makefile(self, mode="r", buffering=None, *,
                 encoding=None, errors=None, newline=None):
        """makefile(...) -> an I/O stream connected to the socket

        The arguments are as for io.open() after the filename, except the only
        supported mode values are 'r' (default), 'w' and 'b'.
        """
        # XXX refactor to share code?
        if not set(mode) <= {"r", "w", "b"}:
            raise ValueError("invalid mode %r (only r, w, b allowed)" % (mode,))
        writing = "w" in mode
        reading = "r" in mode or not writing
        assert reading or writing
        binary = "b" in mode
        rawmode = ""
        if reading:
            rawmode += "r"
        if writing:
            rawmode += "w"
        raw = SocketIO(self, rawmode)
        self._io_refs += 1
        if buffering is None:
            buffering = -1
        if buffering < 0:
            buffering = io.DEFAULT_BUFFER_SIZE
        if buffering == 0:
            if not binary:
                raise ValueError("unbuffered streams must be binary")
            return raw
        if reading and writing:
            buffer = io.BufferedRWPair(raw, raw, buffering)
        elif reading:
            buffer = io.BufferedReader(raw, buffering)
        else:
            assert writing
            buffer = io.BufferedWriter(raw, buffering)
        if binary:
            return buffer
        text = io.TextIOWrapper(buffer, encoding, errors, newline)
        text.mode = mode
        return text

    if hasattr(os, 'sendfile'):

        def _sendfile_use_sendfile(self, file, offset=0, count=None):
            self._check_sendfile_params(file, offset, count)
            sockno = self.fileno()
            try:
                fileno = file.fileno()
            except (AttributeError, io.UnsupportedOperation) as err:
                raise _GiveupOnSendfile(err)  # not a regular file
            try:
                fsize = os.fstat(fileno).st_size
            except OSError as err:
                raise _GiveupOnSendfile(err)  # not a regular file
            if not fsize:
                return 0  # empty file
            blocksize = fsize if not count else count

            timeout = self.gettimeout()
            if timeout == 0:
                raise ValueError("non-blocking sockets are not supported")
            # poll/select have the advantage of not requiring any
            # extra file descriptor, contrarily to epoll/kqueue
            # (also, they require a single syscall).
            if hasattr(selectors, 'PollSelector'):
                selector = selectors.PollSelector()
            else:
                selector = selectors.SelectSelector()
            selector.register(sockno, selectors.EVENT_WRITE)

            total_sent = 0
            # localize variable access to minimize overhead
            selector_select = selector.select
            os_sendfile = os.sendfile
            try:
                while True:
                    if timeout and not selector_select(timeout):
                        raise _socket.timeout('timed out')
                    if count:
                        blocksize = count - total_sent
                        if blocksize <= 0:
                            break
                    try:
                        sent = os_sendfile(sockno, fileno, offset, blocksize)
                    except BlockingIOError:
                        if not timeout:
                            # Block until the socket is ready to send some
                            # data; avoids hogging CPU resources.
                            selector_select()
                        continue
                    except OSError as err:
                        if total_sent == 0:
                            # We can get here for different reasons, the main
                            # one being 'file' is not a regular mmap(2)-like
                            # file, in which case we'll fall back on using
                            # plain send().
                            raise _GiveupOnSendfile(err)
                        raise err from None
                    else:
                        if sent == 0:
                            break  # EOF
                        offset += sent
                        total_sent += sent
                return total_sent
            finally:
                if total_sent > 0 and hasattr(file, 'seek'):
                    file.seek(offset)
    else:
        def _sendfile_use_sendfile(self, file, offset=0, count=None):
            raise _GiveupOnSendfile(
                "os.sendfile() not available on this platform")

    def _sendfile_use_send(self, file, offset=0, count=None):
        self._check_sendfile_params(file, offset, count)
        if self.gettimeout() == 0:
            raise ValueError("non-blocking sockets are not supported")
        if offset:
            file.seek(offset)
        blocksize = min(count, 8192) if count else 8192
        total_sent = 0
        # localize variable access to minimize overhead
        file_read = file.read
        sock_send = self.send
        try:
            while True:
                if count:
                    blocksize = min(count - total_sent, blocksize)
                    if blocksize <= 0:
                        break
                data = memoryview(file_read(blocksize))
                if not data:
                    break  # EOF
                while True:
                    try:
                        sent = sock_send(data)
                    except BlockingIOError:
                        continue
                    else:
                        total_sent += sent
                        if sent < len(data):
                            data = data[sent:]
                        else:
                            break
            return total_sent
        finally:
            if total_sent > 0 and hasattr(file, 'seek'):
                file.seek(offset + total_sent)

    def _check_sendfile_params(self, file, offset, count):
        if 'b' not in getattr(file, 'mode', 'b'):
            raise ValueError("file should be opened in binary mode")
        if not self.type & SOCK_STREAM:
            raise ValueError("only SOCK_STREAM type sockets are supported")
        if count is not None:
            if not isinstance(count, int):
                raise TypeError(
                    "count must be a positive integer (got {!r})".format(count))
            if count <= 0:
                raise ValueError(
                    "count must be a positive integer (got {!r})".format(count))

    def sendfile(self, file, offset=0, count=None):
        """sendfile(file[, offset[, count]]) -> sent

        Send a file until EOF is reached by using high-performance
        os.sendfile() and return the total number of bytes which
        were sent.
        *file* must be a regular file object opened in binary mode.
        If os.sendfile() is not available (e.g. Windows) or file is
        not a regular file socket.send() will be used instead.
        *offset* tells from where to start reading the file.
        If specified, *count* is the total number of bytes to transmit
        as opposed to sending the file until EOF is reached.
        File position is updated on return or also in case of error in
        which case file.tell() can be used to figure out the number of
        bytes which were sent.
        The socket must be of SOCK_STREAM type.
        Non-blocking sockets are not supported.
        """
        try:
            return self._sendfile_use_sendfile(file, offset, count)
        except _GiveupOnSendfile:
            return self._sendfile_use_send(file, offset, count)

    def _decref_socketios(self):
        if self._io_refs > 0:
            self._io_refs -= 1
        if self._closed:
            self.close()

    def _real_close(self, _ss=_socket.socket):
        # This function should not reference any globals. See issue #808164.
        _ss.close(self)

    def close(self):
        # This function should not reference any globals. See issue #808164.
        self._closed = True
        if self._io_refs <= 0:
            self._real_close()

    def detach(self):
        """detach() -> file descriptor

        Close the socket object without closing the underlying file descriptor.
        The object cannot be used after this call, but the file descriptor
        can be reused for other purposes.  The file descriptor is returned.
        """
        self._closed = True
        return super().detach()

    @property
    def family(self):
        """Read-only access to the address family for this socket.
        """
        return _intenum_converter(super().family, AddressFamily)

    @property
    def type(self):
        """Read-only access to the socket type.
        """
        return _intenum_converter(super().type, SocketKind)

    if os.name == 'nt':
        def get_inheritable(self):
            return os.get_handle_inheritable(self.fileno())
        def set_inheritable(self, inheritable):
            os.set_handle_inheritable(self.fileno(), inheritable)
    else:
        def get_inheritable(self):
            return os.get_inheritable(self.fileno())
        def set_inheritable(self, inheritable):
            os.set_inheritable(self.fileno(), inheritable)
    get_inheritable.__doc__ = "Get the inheritable flag of the socket"
    set_inheritable.__doc__ = "Set the inheritable flag of the socket"

def fromfd(fd, family, type, proto=0):
    """ fromfd(fd, family, type[, proto]) -> socket object

    Create a socket object from a duplicate of the given file
    descriptor.  The remaining arguments are the same as for socket().
    """
    nfd = dup(fd)
    return socket(family, type, proto, nfd)

if hasattr(_socket.socket, "share"):
    def fromshare(info):
        """ fromshare(info) -> socket object

        Create a socket object from the bytes object returned by
        socket.share(pid).
        """
        return socket(0, 0, 0, info)
    __all__.append("fromshare")

if hasattr(_socket, "socketpair"):

    def socketpair(family=None, type=SOCK_STREAM, proto=0):
        """socketpair([family[, type[, proto]]]) -> (socket object, socket object)

        Create a pair of socket objects from the sockets returned by the platform
        socketpair() function.
        The arguments are the same as for socket() except the default family is
        AF_UNIX if defined on the platform; otherwise, the default is AF_INET.
        """
        if family is None:
            try:
                family = AF_UNIX
            except NameError:
                family = AF_INET
        a, b = _socket.socketpair(family, type, proto)
        a = socket(family, type, proto, a.detach())
        b = socket(family, type, proto, b.detach())
        return a, b

else:

    # Origin: https://gist.github.com/4325783, by Geert Jansen.  Public domain.
    def socketpair(family=AF_INET, type=SOCK_STREAM, proto=0):
        if family == AF_INET:
            host = _LOCALHOST
        elif family == AF_INET6:
            host = _LOCALHOST_V6
        else:
            raise ValueError("Only AF_INET and AF_INET6 socket address families "
                             "are supported")
        if type != SOCK_STREAM:
            raise ValueError("Only SOCK_STREAM socket type is supported")
        if proto != 0:
            raise ValueError("Only protocol zero is supported")

        # We create a connected TCP socket. Note the trick with
        # setblocking(False) that prevents us from having to create a thread.
        lsock = socket(family, type, proto)
        try:
            lsock.bind((host, 0))
            lsock.listen()
            # On IPv6, ignore flow_info and scope_id
            addr, port = lsock.getsockname()[:2]
            csock = socket(family, type, proto)
            try:
                csock.setblocking(False)
                try:
                    csock.connect((addr, port))
                except (BlockingIOError, InterruptedError):
                    pass
                csock.setblocking(True)
                ssock, _ = lsock.accept()
            except:
                csock.close()
                raise
        finally:
            lsock.close()
        return (ssock, csock)
    __all__.append("socketpair")

socketpair.__doc__ = """socketpair([family[, type[, proto]]]) -> (socket object, socket object)
Create a pair of socket objects from the sockets returned by the platform
socketpair() function.
The arguments are the same as for socket() except the default family is AF_UNIX
if defined on the platform; otherwise, the default is AF_INET.
"""

_blocking_errnos = { EAGAIN, EWOULDBLOCK }

class SocketIO(io.RawIOBase):

    """Raw I/O implementation for stream sockets.

    This class supports the makefile() method on sockets.  It provides
    the raw I/O interface on top of a socket object.
    """

    # One might wonder why not let FileIO do the job instead.  There are two
    # main reasons why FileIO is not adapted:
    # - it wouldn't work under Windows (where you can't used read() and
    #   write() on a socket handle)
    # - it wouldn't work with socket timeouts (FileIO would ignore the
    #   timeout and consider the socket non-blocking)

    # XXX More docs

    def __init__(self, sock, mode):
        if mode not in ("r", "w", "rw", "rb", "wb", "rwb"):
            raise ValueError("invalid mode: %r" % mode)
        io.RawIOBase.__init__(self)
        self._sock = sock
        if "b" not in mode:
            mode += "b"
        self._mode = mode
        self._reading = "r" in mode
        self._writing = "w" in mode
        self._timeout_occurred = False

    def readinto(self, b):
        """Read up to len(b) bytes into the writable buffer *b* and return
        the number of bytes read.  If the socket is non-blocking and no bytes
        are available, None is returned.

        If *b* is non-empty, a 0 return value indicates that the connection
        was shutdown at the other end.
        """
        self._checkClosed()
        self._checkReadable()
        if self._timeout_occurred:
            raise OSError("cannot read from timed out object")
        while True:
            try:
                return self._sock.recv_into(b)
            except timeout:
                self._timeout_occurred = True
                raise
            except error as e:
                if e.args[0] in _blocking_errnos:
                    return None
                raise

    def write(self, b):
        """Write the given bytes or bytearray object *b* to the socket
        and return the number of bytes written.  This can be less than
        len(b) if not all data could be written.  If the socket is
        non-blocking and no bytes could be written None is returned.
        """
        self._checkClosed()
        self._checkWritable()
        try:
            return self._sock.send(b)
        except error as e:
            # XXX what about EINTR?
            if e.args[0] in _blocking_errnos:
                return None
            raise

    def readable(self):
        """True if the SocketIO is open for reading.
        """
        if self.closed:
            raise ValueError("I/O operation on closed socket.")
        return self._reading

    def writable(self):
        """True if the SocketIO is open for writing.
        """
        if self.closed:
            raise ValueError("I/O operation on closed socket.")
        return self._writing

    def seekable(self):
        """True if the SocketIO is open for seeking.
        """
        if self.closed:
            raise ValueError("I/O operation on closed socket.")
        return super().seekable()

    def fileno(self):
        """Return the file descriptor of the underlying socket.
        """
        self._checkClosed()
        return self._sock.fileno()

    @property
    def name(self):
        if not self.closed:
            return self.fileno()
        else:
            return -1

    @property
    def mode(self):
        return self._mode

    def close(self):
        """Close the SocketIO object.  This doesn't close the underlying
        socket, except if all references to it have disappeared.
        """
        if self.closed:
            return
        io.RawIOBase.close(self)
        self._sock._decref_socketios()
        self._sock = None


def getfqdn(name=''):
    """Get fully qualified domain name from name.

    An empty argument is interpreted as meaning the local host.

    First the hostname returned by gethostbyaddr() is checked, then
    possibly existing aliases. In case no FQDN is available, hostname
    from gethostname() is returned.
    """
    name = name.strip()
    if not name or name == '0.0.0.0':
        name = gethostname()
    try:
        hostname, aliases, ipaddrs = gethostbyaddr(name)
    except error:
        pass
    else:
        aliases.insert(0, hostname)
        for name in aliases:
            if '.' in name:
                break
        else:
            name = hostname
    return name


_GLOBAL_DEFAULT_TIMEOUT = object()

def create_connection(address, timeout=_GLOBAL_DEFAULT_TIMEOUT,
                      source_address=None):
    """Connect to *address* and return the socket object.

    Convenience function.  Connect to *address* (a 2-tuple ``(host,
    port)``) and return the socket object.  Passing the optional
    *timeout* parameter will set the timeout on the socket instance
    before attempting to connect.  If no *timeout* is supplied, the
    global default timeout setting returned by :func:`getdefaulttimeout`
    is used.  If *source_address* is set it must be a tuple of (host, port)
    for the socket to bind as a source address before making the connection.
    A host of '' or port 0 tells the OS to use the default.
    """

    host, port = address
    err = None
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
        af, socktype, proto, canonname, sa = res
        sock = None
        try:
            sock = socket(af, socktype, proto)
            if timeout is not _GLOBAL_DEFAULT_TIMEOUT:
                sock.settimeout(timeout)
            if source_address:
                sock.bind(source_address)
            sock.connect(sa)
            # Break explicitly a reference cycle
            err = None
            return sock

        except error as _:
            err = _
            if sock is not None:
                sock.close()

    if err is not None:
        raise err
    else:
        raise error("getaddrinfo returns an empty list")

def getaddrinfo(host, port, family=0, type=0, proto=0, flags=0):
    """Resolve host and port into list of address info entries.

    Translate the host/port argument into a sequence of 5-tuples that contain
    all the necessary arguments for creating a socket connected to that service.
    host is a domain name, a string representation of an IPv4/v6 address or
    None. port is a string service name such as 'http', a numeric port number or
    None. By passing None as the value of host and port, you can pass NULL to
    the underlying C API.

    The family, type and proto arguments can be optionally specified in order to
    narrow the list of addresses returned. Passing zero as a value for each of
    these arguments selects the full range of results.
    """
    # We override this function since we want to translate the numeric family
    # and socket type values to enum constants.
    addrlist = []
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
        af, socktype, proto, canonname, sa = res
        addrlist.append((_intenum_converter(af, AddressFamily),
                         _intenum_converter(socktype, SocketKind),
                         proto, canonname, sa))
    return addrlist

_socket.py

# encoding: utf-8
# module _socket
# from (pre-generated)
# by generator 1.147
"""
Implementation module for socket operations.

See the socket module for documentation.
"""
# no imports

# Variables with simple values

AF_APPLETALK = 16
AF_DECnet = 12
AF_INET = 2
AF_INET6 = 23
AF_IPX = 6
AF_IRDA = 26
AF_SNA = 11
AF_UNSPEC = 0

AI_ADDRCONFIG = 1024
AI_ALL = 256
AI_CANONNAME = 2
AI_NUMERICHOST = 4
AI_NUMERICSERV = 8
AI_PASSIVE = 1
AI_V4MAPPED = 2048

EAI_AGAIN = 11002
EAI_BADFLAGS = 10022
EAI_FAIL = 11003
EAI_FAMILY = 10047
EAI_MEMORY = 8
EAI_NODATA = 11001
EAI_NONAME = 11001
EAI_SERVICE = 10109
EAI_SOCKTYPE = 10044

has_ipv6 = True

INADDR_ALLHOSTS_GROUP = -536870911

INADDR_ANY = 0
INADDR_BROADCAST = -1
INADDR_LOOPBACK = 2130706433

INADDR_MAX_LOCAL_GROUP = -536870657

INADDR_NONE = -1

INADDR_UNSPEC_GROUP = -536870912

IPPORT_RESERVED = 1024
IPPORT_USERRESERVED = 5000

IPPROTO_ICMP = 1
IPPROTO_IP = 0
IPPROTO_RAW = 255
IPPROTO_TCP = 6
IPPROTO_UDP = 17

IPV6_CHECKSUM = 26
IPV6_DONTFRAG = 14
IPV6_HOPLIMIT = 21
IPV6_HOPOPTS = 1

IPV6_JOIN_GROUP = 12

IPV6_LEAVE_GROUP = 13

IPV6_MULTICAST_HOPS = 10
IPV6_MULTICAST_IF = 9
IPV6_MULTICAST_LOOP = 11

IPV6_PKTINFO = 19
IPV6_RECVRTHDR = 38
IPV6_RECVTCLASS = 40
IPV6_RTHDR = 32
IPV6_TCLASS = 39

IPV6_UNICAST_HOPS = 4

IPV6_V6ONLY = 27

IP_ADD_MEMBERSHIP = 12

IP_DROP_MEMBERSHIP = 13

IP_HDRINCL = 2

IP_MULTICAST_IF = 9
IP_MULTICAST_LOOP = 11
IP_MULTICAST_TTL = 10

IP_OPTIONS = 1
IP_RECVDSTADDR = 25
IP_TOS = 3
IP_TTL = 4

MSG_BCAST = 1024
MSG_CTRUNC = 512
MSG_DONTROUTE = 4
MSG_ERRQUEUE = 4096
MSG_MCAST = 2048
MSG_OOB = 1
MSG_PEEK = 2
MSG_TRUNC = 256
MSG_WAITALL = 8

NI_DGRAM = 16
NI_MAXHOST = 1025
NI_MAXSERV = 32
NI_NAMEREQD = 4
NI_NOFQDN = 1
NI_NUMERICHOST = 2
NI_NUMERICSERV = 8

RCVALL_MAX = 3
RCVALL_OFF = 0
RCVALL_ON = 1
RCVALL_SOCKETLEVELONLY = 2

SHUT_RD = 0
SHUT_RDWR = 2
SHUT_WR = 1

SIO_KEEPALIVE_VALS = 2550136836

SIO_LOOPBACK_FAST_PATH = 2550136848

SIO_RCVALL = 2550136833

SOCK_DGRAM = 2
SOCK_RAW = 3
SOCK_RDM = 4
SOCK_SEQPACKET = 5
SOCK_STREAM = 1

SOL_IP = 0
SOL_SOCKET = 65535
SOL_TCP = 6
SOL_UDP = 17

SOMAXCONN = 2147483647
SO_ACCEPTCONN = 2
SO_BROADCAST = 32
SO_DEBUG = 1
SO_DONTROUTE = 16
SO_ERROR = 4103
SO_EXCLUSIVEADDRUSE = -5
SO_KEEPALIVE = 8
SO_LINGER = 128
SO_OOBINLINE = 256
SO_RCVBUF = 4098
SO_RCVLOWAT = 4100
SO_RCVTIMEO = 4102
SO_REUSEADDR = 4
SO_SNDBUF = 4097
SO_SNDLOWAT = 4099
SO_SNDTIMEO = 4101
SO_TYPE = 4104
SO_USELOOPBACK = 64

TCP_FASTOPEN = 15
TCP_KEEPCNT = 16
TCP_KEEPIDLE = 3
TCP_KEEPINTVL = 17
TCP_MAXSEG = 4
TCP_NODELAY = 1

# functions

def close(integer): # real signature unknown; restored from __doc__
    """
    close(integer) -> None
    
    Close an integer socket file descriptor.  This is like os.close(), but for
    sockets; on some platforms os.close() won't work for socket file descriptors.
    """
    pass

def dup(integer): # real signature unknown; restored from __doc__
    """
    dup(integer) -> integer
    
    Duplicate an integer socket file descriptor.  This is like os.dup(), but for
    sockets; on some platforms os.dup() won't work for socket file descriptors.
    """
    return 0

def getaddrinfo(host, port, family=None, type=None, proto=None, flags=None): # real signature unknown; restored from __doc__
    """
    getaddrinfo(host, port [, family, type, proto, flags])
        -> list of (family, type, proto, canonname, sockaddr)
    
    Resolve host and port into addrinfo struct.
    """
    return []

def getdefaulttimeout(): # real signature unknown; restored from __doc__
    """
    getdefaulttimeout() -> timeout
    
    Returns the default timeout in seconds (float) for new socket objects.
    A value of None indicates that new socket objects have no timeout.
    When the socket module is first imported, the default is None.
    """
    return timeout

def gethostbyaddr(host): # real signature unknown; restored from __doc__
    """
    gethostbyaddr(host) -> (name, aliaslist, addresslist)
    
    Return the true host name, a list of aliases, and a list of IP addresses,
    for a host.  The host argument is a string giving a host name or IP number.
    """
    pass

def gethostbyname(host): # real signature unknown; restored from __doc__
    """
    gethostbyname(host) -> address
    
    Return the IP address (a string of the form '255.255.255.255') for a host.
    """
    pass

def gethostbyname_ex(host): # real signature unknown; restored from __doc__
    """
    gethostbyname_ex(host) -> (name, aliaslist, addresslist)
    
    Return the true host name, a list of aliases, and a list of IP addresses,
    for a host.  The host argument is a string giving a host name or IP number.
    """
    pass

def gethostname(): # real signature unknown; restored from __doc__
    """
    gethostname() -> string
    
    Return the current host name.
    """
    return ""

def getnameinfo(sockaddr, flags): # real signature unknown; restored from __doc__
    """
    getnameinfo(sockaddr, flags) --> (host, port)
    
    Get host and port for a sockaddr.
    """
    pass

def getprotobyname(name): # real signature unknown; restored from __doc__
    """
    getprotobyname(name) -> integer
    
    Return the protocol number for the named protocol.  (Rarely used.)
    """
    return 0

def getservbyname(servicename, protocolname=None): # real signature unknown; restored from __doc__
    """
    getservbyname(servicename[, protocolname]) -> integer
    
    Return a port number from a service name and protocol name.
    The optional protocol name, if given, should be 'tcp' or 'udp',
    otherwise any protocol will match.
    """
    return 0

def getservbyport(port, protocolname=None): # real signature unknown; restored from __doc__
    """
    getservbyport(port[, protocolname]) -> string
    
    Return the service name from a port number and protocol name.
    The optional protocol name, if given, should be 'tcp' or 'udp',
    otherwise any protocol will match.
    """
    return ""

def htonl(integer): # real signature unknown; restored from __doc__
    """
    htonl(integer) -> integer
    
    Convert a 32-bit integer from host to network byte order.
    """
    return 0

def htons(integer): # real signature unknown; restored from __doc__
    """
    htons(integer) -> integer
    
    Convert a 16-bit unsigned integer from host to network byte order.
    Note that in case the received integer does not fit in 16-bit unsigned
    integer, but does fit in a positive C int, it is silently truncated to
    16-bit unsigned integer.
    However, this silent truncation feature is deprecated, and will raise an 
    exception in future versions of Python.
    """
    return 0

def inet_aton(string): # real signature unknown; restored from __doc__
    """
    inet_aton(string) -> bytes giving packed 32-bit IP representation
    
    Convert an IP address in string format (123.45.67.89) to the 32-bit packed
    binary format used in low-level network functions.
    """
    return b""

def inet_ntoa(packed_ip): # real signature unknown; restored from __doc__
    """
    inet_ntoa(packed_ip) -> ip_address_string
    
    Convert an IP address from 32-bit packed binary format to string format
    """
    pass

def inet_ntop(af, packed_ip): # real signature unknown; restored from __doc__
    """
    inet_ntop(af, packed_ip) -> string formatted IP address
    
    Convert a packed IP address of the given family to string format.
    """
    return ""

def inet_pton(af, ip): # real signature unknown; restored from __doc__
    """
    inet_pton(af, ip) -> packed IP address string
    
    Convert an IP address from string format to a packed string suitable
    for use with low-level network functions.
    """
    pass

def ntohl(integer): # real signature unknown; restored from __doc__
    """
    ntohl(integer) -> integer
    
    Convert a 32-bit integer from network to host byte order.
    """
    return 0

def ntohs(integer): # real signature unknown; restored from __doc__
    """
    ntohs(integer) -> integer
    
    Convert a 16-bit unsigned integer from network to host byte order.
    Note that in case the received integer does not fit in 16-bit unsigned
    integer, but does fit in a positive C int, it is silently truncated to
    16-bit unsigned integer.
    However, this silent truncation feature is deprecated, and will raise an 
    exception in future versions of Python.
    """
    return 0

def setdefaulttimeout(timeout): # real signature unknown; restored from __doc__
    """
    setdefaulttimeout(timeout)
    
    Set the default timeout in seconds (float) for new socket objects.
    A value of None indicates that new socket objects have no timeout.
    When the socket module is first imported, the default is None.
    """
    pass

# classes

class error(Exception):
    """ Base class for I/O related errors. """
    def __init__(self, *args, **kwargs): # real signature unknown
        pass

    @staticmethod # known case of __new__
    def __new__(*args, **kwargs): # real signature unknown
        """ Create and return a new object.  See help(type) for accurate signature. """
        pass

    def __reduce__(self, *args, **kwargs): # real signature unknown
        pass

    def __str__(self, *args, **kwargs): # real signature unknown
        """ Return str(self). """
        pass

    characters_written = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default

    errno = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """POSIX exception code"""

    filename = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """exception filename"""

    filename2 = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """second exception filename"""

    strerror = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """exception strerror"""

    winerror = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """Win32 exception code"""



class gaierror(OSError):
    # no doc
    def __init__(self, *args, **kwargs): # real signature unknown
        pass

    __weakref__ = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """list of weak references to the object (if defined)"""



class herror(OSError):
    # no doc
    def __init__(self, *args, **kwargs): # real signature unknown
        pass

    __weakref__ = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """list of weak references to the object (if defined)"""



class SocketType(object):
    """
    socket(family=AF_INET, type=SOCK_STREAM, proto=0) -> socket object
    socket(family=-1, type=-1, proto=-1, fileno=None) -> socket object
    
    Open a socket of the given type.  The family argument specifies the
    address family; it defaults to AF_INET.  The type argument specifies
    whether this is a stream (SOCK_STREAM, this is the default)
    or datagram (SOCK_DGRAM) socket.  The protocol argument defaults to 0,
    specifying the default protocol.  Keyword arguments are accepted.
    The socket is created as non-inheritable.
    
    When a fileno is passed in, family, type and proto are auto-detected,
    unless they are explicitly set.
    
    A socket object represents one endpoint of a network connection.
    
    Methods of socket objects (keyword arguments not allowed):
    
    _accept() -- accept connection, returning new socket fd and client address
    bind(addr) -- bind the socket to a local address
    close() -- close the socket
    connect(addr) -- connect the socket to a remote address
    connect_ex(addr) -- connect, return an error code instead of an exception
    dup() -- return a new socket fd duplicated from fileno()
    fileno() -- return underlying file descriptor
    getpeername() -- return remote address [*]
    getsockname() -- return local address
    getsockopt(level, optname[, buflen]) -- get socket options
    gettimeout() -- return timeout or None
    listen([n]) -- start listening for incoming connections
    recv(buflen[, flags]) -- receive data
    recv_into(buffer[, nbytes[, flags]]) -- receive data (into a buffer)
    recvfrom(buflen[, flags]) -- receive data and sender's address
    recvfrom_into(buffer[, nbytes, [, flags])
      -- receive data and sender's address (into a buffer)
    sendall(data[, flags]) -- send all data
    send(data[, flags]) -- send data, may not send all of it
    sendto(data[, flags], addr) -- send data to a given address
    setblocking(0 | 1) -- set or clear the blocking I/O flag
    getblocking() -- return True if socket is blocking, False if non-blocking
    setsockopt(level, optname, value[, optlen]) -- set socket options
    settimeout(None | float) -- set or clear the timeout
    shutdown(how) -- shut down traffic in one or both directions
    if_nameindex() -- return all network interface indices and names
    if_nametoindex(name) -- return the corresponding interface index
    if_indextoname(index) -- return the corresponding interface name
    
     [*] not available on all platforms!
    """
    def bind(self, address): # real signature unknown; restored from __doc__
        """
        bind(address)
        
        Bind the socket to a local address.  For IP sockets, the address is a
        pair (host, port); the host must refer to the local host. For raw packet
        sockets the address is a tuple (ifname, proto [,pkttype [,hatype [,addr]]])
        """
        pass

    def close(self): # real signature unknown; restored from __doc__
        """
        close()
        
        Close the socket.  It cannot be used after this call.
        """
        pass

    def connect(self, address): # real signature unknown; restored from __doc__
        """
        connect(address)
        
        Connect the socket to a remote address.  For IP sockets, the address
        is a pair (host, port).
        """
        pass

    def connect_ex(self, address): # real signature unknown; restored from __doc__
        """
        connect_ex(address) -> errno
        
        This is like connect(address), but returns an error code (the errno value)
        instead of raising an exception when an error occurs.
        """
        pass

    def detach(self): # real signature unknown; restored from __doc__
        """
        detach()
        
        Close the socket object without closing the underlying file descriptor.
        The object cannot be used after this call, but the file descriptor
        can be reused for other purposes.  The file descriptor is returned.
        """
        pass

    def fileno(self): # real signature unknown; restored from __doc__
        """
        fileno() -> integer
        
        Return the integer file descriptor of the socket.
        """
        return 0

    def getblocking(self): # real signature unknown; restored from __doc__
        """
        getblocking()
        
        Returns True if socket is in blocking mode, or False if it
        is in non-blocking mode.
        """
        pass

    def getpeername(self): # real signature unknown; restored from __doc__
        """
        getpeername() -> address info
        
        Return the address of the remote endpoint.  For IP sockets, the address
        info is a pair (hostaddr, port).
        """
        pass

    def getsockname(self): # real signature unknown; restored from __doc__
        """
        getsockname() -> address info
        
        Return the address of the local endpoint.  For IP sockets, the address
        info is a pair (hostaddr, port).
        """
        pass

    def getsockopt(self, level, option, buffersize=None): # real signature unknown; restored from __doc__
        """
        getsockopt(level, option[, buffersize]) -> value
        
        Get a socket option.  See the Unix manual for level and option.
        If a nonzero buffersize argument is given, the return value is a
        string of that length; otherwise it is an integer.
        """
        pass

    def gettimeout(self): # real signature unknown; restored from __doc__
        """
        gettimeout() -> timeout
        
        Returns the timeout in seconds (float) associated with socket 
        operations. A timeout of None indicates that timeouts on socket 
        operations are disabled.
        """
        return timeout

    def ioctl(self, cmd, option): # real signature unknown; restored from __doc__
        """
        ioctl(cmd, option) -> long
        
        Control the socket with WSAIoctl syscall. Currently supported 'cmd' values are
        SIO_RCVALL:  'option' must be one of the socket.RCVALL_* constants.
        SIO_KEEPALIVE_VALS:  'option' is a tuple of (onoff, timeout, interval).
        SIO_LOOPBACK_FAST_PATH: 'option' is a boolean value, and is disabled by default
        """
        return 0

    def listen(self, backlog=None): # real signature unknown; restored from __doc__
        """
        listen([backlog])
        
        Enable a server to accept connections.  If backlog is specified, it must be
        at least 0 (if it is lower, it is set to 0); it specifies the number of
        unaccepted connections that the system will allow before refusing new
        connections. If not specified, a default reasonable value is chosen.
        """
        pass

    def recv(self, buffersize, flags=None): # real signature unknown; restored from __doc__
        """
        recv(buffersize[, flags]) -> data
        
        Receive up to buffersize bytes from the socket.  For the optional flags
        argument, see the Unix manual.  When no data is available, block until
        at least one byte is available or until the remote end is closed.  When
        the remote end is closed and all data is read, return the empty string.
        """
        pass

    def recvfrom(self, buffersize, flags=None): # real signature unknown; restored from __doc__
        """
        recvfrom(buffersize[, flags]) -> (data, address info)
        
        Like recv(buffersize, flags) but also return the sender's address info.
        """
        pass

    def recvfrom_into(self, buffer, nbytes=None, flags=None): # real signature unknown; restored from __doc__
        """
        recvfrom_into(buffer[, nbytes[, flags]]) -> (nbytes, address info)
        
        Like recv_into(buffer[, nbytes[, flags]]) but also return the sender's address info.
        """
        pass

    def recv_into(self, buffer, nbytes=None, flags=None): # real signature unknown; restored from __doc__
        """
        recv_into(buffer, [nbytes[, flags]]) -> nbytes_read
        
        A version of recv() that stores its data into a buffer rather than creating 
        a new string.  Receive up to buffersize bytes from the socket.  If buffersize 
        is not specified (or 0), receive up to the size available in the given buffer.
        
        See recv() for documentation about the flags.
        """
        pass

    def send(self, data, flags=None): # real signature unknown; restored from __doc__
        """
        send(data[, flags]) -> count
        
        Send a data string to the socket.  For the optional flags
        argument, see the Unix manual.  Return the number of bytes
        sent; this may be less than len(data) if the network is busy.
        """
        pass

    def sendall(self, data, flags=None): # real signature unknown; restored from __doc__
        """
        sendall(data[, flags])
        
        Send a data string to the socket.  For the optional flags
        argument, see the Unix manual.  This calls send() repeatedly
        until all data is sent.  If an error occurs, it's impossible
        to tell how much data has been sent.
        """
        pass

    def sendto(self, data, flags=None, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
        """
        sendto(data[, flags], address) -> count
        
        Like send(data, flags) but allows specifying the destination address.
        For IP sockets, the address is a pair (hostaddr, port).
        """
        pass

    def setblocking(self, flag): # real signature unknown; restored from __doc__
        """
        setblocking(flag)
        
        Set the socket to blocking (flag is true) or non-blocking (false).
        setblocking(True) is equivalent to settimeout(None);
        setblocking(False) is equivalent to settimeout(0.0).
        """
        pass

    def setsockopt(self, level, option, value): # real signature unknown; restored from __doc__
        """
        setsockopt(level, option, value: int)
        setsockopt(level, option, value: buffer)
        setsockopt(level, option, None, optlen: int)
        
        Set a socket option.  See the Unix manual for level and option.
        The value argument can either be an integer, a string buffer, or 
        None, optlen.
        """
        pass

    def settimeout(self, timeout): # real signature unknown; restored from __doc__
        """
        settimeout(timeout)
        
        Set a timeout on socket operations.  'timeout' can be a float,
        giving in seconds, or None.  Setting a timeout of None disables
        the timeout feature and is equivalent to setblocking(1).
        Setting a timeout of zero is the same as setblocking(0).
        """
        pass

    def share(self, process_id): # real signature unknown; restored from __doc__
        """
        share(process_id) -> bytes
        
        Share the socket with another process.  The target process id
        must be provided and the resulting bytes object passed to the target
        process.  There the shared socket can be instantiated by calling
        socket.fromshare().
        """
        return b""

    def shutdown(self, flag): # real signature unknown; restored from __doc__
        """
        shutdown(flag)
        
        Shut down the reading side of the socket (flag == SHUT_RD), the writing side
        of the socket (flag == SHUT_WR), or both ends (flag == SHUT_RDWR).
        """
        pass

    def _accept(self): # real signature unknown; restored from __doc__
        """
        _accept() -> (integer, address info)
        
        Wait for an incoming connection.  Return a new socket file descriptor
        representing the connection, and the address of the client.
        For IP sockets, the address info is a pair (hostaddr, port).
        """
        pass

    def __del__(self, *args, **kwargs): # real signature unknown
        pass

    def __getattribute__(self, *args, **kwargs): # real signature unknown
        """ Return getattr(self, name). """
        pass

    def __init__(self, *args, **kwargs): # real signature unknown
        pass

    @staticmethod # known case of __new__
    def __new__(*args, **kwargs): # real signature unknown
        """ Create and return a new object.  See help(type) for accurate signature. """
        pass

    def __repr__(self, *args, **kwargs): # real signature unknown
        """ Return repr(self). """
        pass

    family = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the socket family"""

    proto = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the socket protocol"""

    timeout = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the socket timeout"""

    type = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the socket type"""



socket = SocketType


class timeout(OSError):
    # no doc
    def __init__(self, *args, **kwargs): # real signature unknown
        pass

    __weakref__ = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """list of weak references to the object (if defined)"""



# variables with complex values

CAPI = None # (!) real value is '<capsule object "_socket.CAPI" at 0x00000207994EBD20>'

__loader__ = None # (!) real value is '<_frozen_importlib_external.ExtensionFileLoader object at 0x000002079944B2B0>'

__spec__ = None # (!) real value is "ModuleSpec(name='_socket', loader=<_frozen_importlib_external.ExtensionFileLoader object at 0x000002079944B2B0>, origin='C:\\\\BuildAgent\\\\system\\\\.persistent_cache\\\\pycharm\\\\pythons4skeletons\\\\python37\\\\DLLs\\\\_socket.pyd')"

socketserver.py

"""Generic socket server classes.

This module tries to capture the various aspects of defining a server:

For socket-based servers:

- address family:
        - AF_INET{,6}: IP (Internet Protocol) sockets (default)
        - AF_UNIX: Unix domain sockets
        - others, e.g. AF_DECNET are conceivable (see <socket.h>
- socket type:
        - SOCK_STREAM (reliable stream, e.g. TCP)
        - SOCK_DGRAM (datagrams, e.g. UDP)

For request-based servers (including socket-based):

- client address verification before further looking at the request
        (This is actually a hook for any processing that needs to look
         at the request before anything else, e.g. logging)
- how to handle multiple requests:
        - synchronous (one request is handled at a time)
        - forking (each request is handled by a new process)
        - threading (each request is handled by a new thread)

The classes in this module favor the server type that is simplest to
write: a synchronous TCP/IP server.  This is bad class design, but
save some typing.  (There's also the issue that a deep class hierarchy
slows down method lookups.)

There are five classes in an inheritance diagram, four of which represent
synchronous servers of four types:

        +------------+
        | BaseServer |
        +------------+
              |
              v
        +-----------+        +------------------+
        | TCPServer |------->| UnixStreamServer |
        +-----------+        +------------------+
              |
              v
        +-----------+        +--------------------+
        | UDPServer |------->| UnixDatagramServer |
        +-----------+        +--------------------+

Note that UnixDatagramServer derives from UDPServer, not from
UnixStreamServer -- the only difference between an IP and a Unix
stream server is the address family, which is simply repeated in both
unix server classes.

Forking and threading versions of each type of server can be created
using the ForkingMixIn and ThreadingMixIn mix-in classes.  For
instance, a threading UDP server class is created as follows:

        class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass

The Mix-in class must come first, since it overrides a method defined
in UDPServer! Setting the various member variables also changes
the behavior of the underlying server mechanism.

To implement a service, you must derive a class from
BaseRequestHandler and redefine its handle() method.  You can then run
various versions of the service by combining one of the server classes
with your request handler class.

The request handler class must be different for datagram or stream
services.  This can be hidden by using the request handler
subclasses StreamRequestHandler or DatagramRequestHandler.

Of course, you still have to use your head!

For instance, it makes no sense to use a forking server if the service
contains state in memory that can be modified by requests (since the
modifications in the child process would never reach the initial state
kept in the parent process and passed to each child).  In this case,
you can use a threading server, but you will probably have to use
locks to avoid two requests that come in nearly simultaneous to apply
conflicting changes to the server state.

On the other hand, if you are building e.g. an HTTP server, where all
data is stored externally (e.g. in the file system), a synchronous
class will essentially render the service "deaf" while one request is
being handled -- which may be for a very long time if a client is slow
to read all the data it has requested.  Here a threading or forking
server is appropriate.

In some cases, it may be appropriate to process part of a request
synchronously, but to finish processing in a forked child depending on
the request data.  This can be implemented by using a synchronous
server and doing an explicit fork in the request handler class
handle() method.

Another approach to handling multiple simultaneous requests in an
environment that supports neither threads nor fork (or where these are
too expensive or inappropriate for the service) is to maintain an
explicit table of partially finished requests and to use a selector to
decide which request to work on next (or whether to handle a new
incoming request).  This is particularly important for stream services
where each client can potentially be connected for a long time (if
threads or subprocesses cannot be used).

Future work:
- Standard classes for Sun RPC (which uses either UDP or TCP)
- Standard mix-in classes to implement various authentication
  and encryption schemes

XXX Open problems:
- What to do with out-of-band data?

BaseServer:
- split generic "request" functionality out into BaseServer class.
  Copyright (C) 2000  Luke Kenneth Casson Leighton <lkcl@samba.org>

  example: read entries from a SQL database (requires overriding
  get_request() to return a table entry from the database).
  entry is processed by a RequestHandlerClass.

"""

# Author of the BaseServer patch: Luke Kenneth Casson Leighton

__version__ = "0.4"


import socket
import selectors
import os
import sys
import threading
from io import BufferedIOBase
from time import monotonic as time

__all__ = ["BaseServer", "TCPServer", "UDPServer",
           "ThreadingUDPServer", "ThreadingTCPServer",
           "BaseRequestHandler", "StreamRequestHandler",
           "DatagramRequestHandler", "ThreadingMixIn"]
if hasattr(os, "fork"):
    __all__.extend(["ForkingUDPServer","ForkingTCPServer", "ForkingMixIn"])
if hasattr(socket, "AF_UNIX"):
    __all__.extend(["UnixStreamServer","UnixDatagramServer",
                    "ThreadingUnixStreamServer",
                    "ThreadingUnixDatagramServer"])

# poll/select have the advantage of not requiring any extra file descriptor,
# contrarily to epoll/kqueue (also, they require a single syscall).
if hasattr(selectors, 'PollSelector'):
    _ServerSelector = selectors.PollSelector
else:
    _ServerSelector = selectors.SelectSelector


class BaseServer:

    """Base class for server classes.

    Methods for the caller:

    - __init__(server_address, RequestHandlerClass)
    - serve_forever(poll_interval=0.5)
    - shutdown()
    - handle_request()  # if you do not use serve_forever()
    - fileno() -> int   # for selector

    Methods that may be overridden:

    - server_bind()
    - server_activate()
    - get_request() -> request, client_address
    - handle_timeout()
    - verify_request(request, client_address)
    - server_close()
    - process_request(request, client_address)
    - shutdown_request(request)
    - close_request(request)
    - service_actions()
    - handle_error()

    Methods for derived classes:

    - finish_request(request, client_address)

    Class variables that may be overridden by derived classes or
    instances:

    - timeout
    - address_family
    - socket_type
    - allow_reuse_address

    Instance variables:

    - RequestHandlerClass
    - socket

    """

    timeout = None

    def __init__(self, server_address, RequestHandlerClass):
        """Constructor.  May be extended, do not override."""
        self.server_address = server_address
        self.RequestHandlerClass = RequestHandlerClass
        self.__is_shut_down = threading.Event()
        self.__shutdown_request = False

    def server_activate(self):
        """Called by constructor to activate the server.

        May be overridden.

        """
        pass

    def serve_forever(self, poll_interval=0.5):
        """Handle one request at a time until shutdown.

        Polls for shutdown every poll_interval seconds. Ignores
        self.timeout. If you need to do periodic tasks, do them in
        another thread.
        """
        self.__is_shut_down.clear()
        try:
            # XXX: Consider using another file descriptor or connecting to the
            # socket to wake this up instead of polling. Polling reduces our
            # responsiveness to a shutdown request and wastes cpu at all other
            # times.
            with _ServerSelector() as selector:
                selector.register(self, selectors.EVENT_READ)

                while not self.__shutdown_request:
                    ready = selector.select(poll_interval)
                    # bpo-35017: shutdown() called during select(), exit immediately.
                    if self.__shutdown_request:
                        break
                    if ready:
                        self._handle_request_noblock()

                    self.service_actions()
        finally:
            self.__shutdown_request = False
            self.__is_shut_down.set()

    def shutdown(self):
        """Stops the serve_forever loop.

        Blocks until the loop has finished. This must be called while
        serve_forever() is running in another thread, or it will
        deadlock.
        """
        self.__shutdown_request = True
        self.__is_shut_down.wait()

    def service_actions(self):
        """Called by the serve_forever() loop.

        May be overridden by a subclass / Mixin to implement any code that
        needs to be run during the loop.
        """
        pass

    # The distinction between handling, getting, processing and finishing a
    # request is fairly arbitrary.  Remember:
    #
    # - handle_request() is the top-level call.  It calls selector.select(),
    #   get_request(), verify_request() and process_request()
    # - get_request() is different for stream or datagram sockets
    # - process_request() is the place that may fork a new process or create a
    #   new thread to finish the request
    # - finish_request() instantiates the request handler class; this
    #   constructor will handle the request all by itself

    def handle_request(self):
        """Handle one request, possibly blocking.

        Respects self.timeout.
        """
        # Support people who used socket.settimeout() to escape
        # handle_request before self.timeout was available.
        timeout = self.socket.gettimeout()
        if timeout is None:
            timeout = self.timeout
        elif self.timeout is not None:
            timeout = min(timeout, self.timeout)
        if timeout is not None:
            deadline = time() + timeout

        # Wait until a request arrives or the timeout expires - the loop is
        # necessary to accommodate early wakeups due to EINTR.
        with _ServerSelector() as selector:
            selector.register(self, selectors.EVENT_READ)

            while True:
                ready = selector.select(timeout)
                if ready:
                    return self._handle_request_noblock()
                else:
                    if timeout is not None:
                        timeout = deadline - time()
                        if timeout < 0:
                            return self.handle_timeout()

    def _handle_request_noblock(self):
        """Handle one request, without blocking.

        I assume that selector.select() has returned that the socket is
        readable before this function was called, so there should be no risk of
        blocking in get_request().
        """
        try:
            request, client_address = self.get_request()
        except OSError:
            return
        if self.verify_request(request, client_address):
            try:
                self.process_request(request, client_address)
            except Exception:
                self.handle_error(request, client_address)
                self.shutdown_request(request)
            except:
                self.shutdown_request(request)
                raise
        else:
            self.shutdown_request(request)

    def handle_timeout(self):
        """Called if no new request arrives within self.timeout.

        Overridden by ForkingMixIn.
        """
        pass

    def verify_request(self, request, client_address):
        """Verify the request.  May be overridden.

        Return True if we should proceed with this request.

        """
        return True

    def process_request(self, request, client_address):
        """Call finish_request.

        Overridden by ForkingMixIn and ThreadingMixIn.

        """
        self.finish_request(request, client_address)
        self.shutdown_request(request)

    def server_close(self):
        """Called to clean-up the server.

        May be overridden.

        """
        pass

    def finish_request(self, request, client_address):
        """Finish one request by instantiating RequestHandlerClass."""
        self.RequestHandlerClass(request, client_address, self)

    def shutdown_request(self, request):
        """Called to shutdown and close an individual request."""
        self.close_request(request)

    def close_request(self, request):
        """Called to clean up an individual request."""
        pass

    def handle_error(self, request, client_address):
        """Handle an error gracefully.  May be overridden.

        The default is to print a traceback and continue.

        """
        print('-'*40, file=sys.stderr)
        print('Exception happened during processing of request from',
            client_address, file=sys.stderr)
        import traceback
        traceback.print_exc()
        print('-'*40, file=sys.stderr)

    def __enter__(self):
        return self

    def __exit__(self, *args):
        self.server_close()


class TCPServer(BaseServer):

    """Base class for various socket-based server classes.

    Defaults to synchronous IP stream (i.e., TCP).

    Methods for the caller:

    - __init__(server_address, RequestHandlerClass, bind_and_activate=True)
    - serve_forever(poll_interval=0.5)
    - shutdown()
    - handle_request()  # if you don't use serve_forever()
    - fileno() -> int   # for selector

    Methods that may be overridden:

    - server_bind()
    - server_activate()
    - get_request() -> request, client_address
    - handle_timeout()
    - verify_request(request, client_address)
    - process_request(request, client_address)
    - shutdown_request(request)
    - close_request(request)
    - handle_error()

    Methods for derived classes:

    - finish_request(request, client_address)

    Class variables that may be overridden by derived classes or
    instances:

    - timeout
    - address_family
    - socket_type
    - request_queue_size (only for stream sockets)
    - allow_reuse_address

    Instance variables:

    - server_address
    - RequestHandlerClass
    - socket

    """

    address_family = socket.AF_INET

    socket_type = socket.SOCK_STREAM

    request_queue_size = 5

    allow_reuse_address = False

    def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True):
        """Constructor.  May be extended, do not override."""
        BaseServer.__init__(self, server_address, RequestHandlerClass)
        self.socket = socket.socket(self.address_family,
                                    self.socket_type)
        if bind_and_activate:
            try:
                self.server_bind()
                self.server_activate()
            except:
                self.server_close()
                raise

    def server_bind(self):
        """Called by constructor to bind the socket.

        May be overridden.

        """
        if self.allow_reuse_address:
            self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.socket.bind(self.server_address)
        self.server_address = self.socket.getsockname()

    def server_activate(self):
        """Called by constructor to activate the server.

        May be overridden.

        """
        self.socket.listen(self.request_queue_size)

    def server_close(self):
        """Called to clean-up the server.

        May be overridden.

        """
        self.socket.close()

    def fileno(self):
        """Return socket file number.

        Interface required by selector.

        """
        return self.socket.fileno()

    def get_request(self):
        """Get the request and client address from the socket.

        May be overridden.

        """
        return self.socket.accept()

    def shutdown_request(self, request):
        """Called to shutdown and close an individual request."""
        try:
            #explicitly shutdown.  socket.close() merely releases
            #the socket and waits for GC to perform the actual close.
            request.shutdown(socket.SHUT_WR)
        except OSError:
            pass #some platforms may raise ENOTCONN here
        self.close_request(request)

    def close_request(self, request):
        """Called to clean up an individual request."""
        request.close()


class UDPServer(TCPServer):

    """UDP server class."""

    allow_reuse_address = False

    socket_type = socket.SOCK_DGRAM

    max_packet_size = 8192

    def get_request(self):
        data, client_addr = self.socket.recvfrom(self.max_packet_size)
        return (data, self.socket), client_addr

    def server_activate(self):
        # No need to call listen() for UDP.
        pass

    def shutdown_request(self, request):
        # No need to shutdown anything.
        self.close_request(request)

    def close_request(self, request):
        # No need to close anything.
        pass

if hasattr(os, "fork"):
    class ForkingMixIn:
        """Mix-in class to handle each request in a new process."""

        timeout = 300
        active_children = None
        max_children = 40
        # If true, server_close() waits until all child processes complete.
        block_on_close = True

        def collect_children(self, *, blocking=False):
            """Internal routine to wait for children that have exited."""
            if self.active_children is None:
                return

            # If we're above the max number of children, wait and reap them until
            # we go back below threshold. Note that we use waitpid(-1) below to be
            # able to collect children in size(<defunct children>) syscalls instead
            # of size(<children>): the downside is that this might reap children
            # which we didn't spawn, which is why we only resort to this when we're
            # above max_children.
            while len(self.active_children) >= self.max_children:
                try:
                    pid, _ = os.waitpid(-1, 0)
                    self.active_children.discard(pid)
                except ChildProcessError:
                    # we don't have any children, we're done
                    self.active_children.clear()
                except OSError:
                    break

            # Now reap all defunct children.
            for pid in self.active_children.copy():
                try:
                    flags = 0 if blocking else os.WNOHANG
                    pid, _ = os.waitpid(pid, flags)
                    # if the child hasn't exited yet, pid will be 0 and ignored by
                    # discard() below
                    self.active_children.discard(pid)
                except ChildProcessError:
                    # someone else reaped it
                    self.active_children.discard(pid)
                except OSError:
                    pass

        def handle_timeout(self):
            """Wait for zombies after self.timeout seconds of inactivity.

            May be extended, do not override.
            """
            self.collect_children()

        def service_actions(self):
            """Collect the zombie child processes regularly in the ForkingMixIn.

            service_actions is called in the BaseServer's serve_forever loop.
            """
            self.collect_children()

        def process_request(self, request, client_address):
            """Fork a new subprocess to process the request."""
            pid = os.fork()
            if pid:
                # Parent process
                if self.active_children is None:
                    self.active_children = set()
                self.active_children.add(pid)
                self.close_request(request)
                return
            else:
                # Child process.
                # This must never return, hence os._exit()!
                status = 1
                try:
                    self.finish_request(request, client_address)
                    status = 0
                except Exception:
                    self.handle_error(request, client_address)
                finally:
                    try:
                        self.shutdown_request(request)
                    finally:
                        os._exit(status)

        def server_close(self):
            super().server_close()
            self.collect_children(blocking=self.block_on_close)


class ThreadingMixIn:
    """Mix-in class to handle each request in a new thread."""

    # Decides how threads will act upon termination of the
    # main process
    daemon_threads = False
    # If true, server_close() waits until all non-daemonic threads terminate.
    block_on_close = True
    # For non-daemonic threads, list of threading.Threading objects
    # used by server_close() to wait for all threads completion.
    _threads = None

    def process_request_thread(self, request, client_address):
        """Same as in BaseServer but as a thread.

        In addition, exception handling is done here.

        """
        try:
            self.finish_request(request, client_address)
        except Exception:
            self.handle_error(request, client_address)
        finally:
            self.shutdown_request(request)

    def process_request(self, request, client_address):
        """Start a new thread to process the request."""
        t = threading.Thread(target = self.process_request_thread,
                             args = (request, client_address))
        t.daemon = self.daemon_threads
        if not t.daemon and self.block_on_close:
            if self._threads is None:
                self._threads = []
            self._threads.append(t)
        t.start()

    def server_close(self):
        super().server_close()
        if self.block_on_close:
            threads = self._threads
            self._threads = None
            if threads:
                for thread in threads:
                    thread.join()


if hasattr(os, "fork"):
    class ForkingUDPServer(ForkingMixIn, UDPServer): pass
    class ForkingTCPServer(ForkingMixIn, TCPServer): pass

class ThreadingUDPServer(ThreadingMixIn, UDPServer): pass
class ThreadingTCPServer(ThreadingMixIn, TCPServer): pass

if hasattr(socket, 'AF_UNIX'):

    class UnixStreamServer(TCPServer):
        address_family = socket.AF_UNIX

    class UnixDatagramServer(UDPServer):
        address_family = socket.AF_UNIX

    class ThreadingUnixStreamServer(ThreadingMixIn, UnixStreamServer): pass

    class ThreadingUnixDatagramServer(ThreadingMixIn, UnixDatagramServer): pass

class BaseRequestHandler:

    """Base class for request handler classes.

    This class is instantiated for each request to be handled.  The
    constructor sets the instance variables request, client_address
    and server, and then calls the handle() method.  To implement a
    specific service, all you need to do is to derive a class which
    defines a handle() method.

    The handle() method can find the request as self.request, the
    client address as self.client_address, and the server (in case it
    needs access to per-server information) as self.server.  Since a
    separate instance is created for each request, the handle() method
    can define other arbitrary instance variables.

    """

    def __init__(self, request, client_address, server):
        self.request = request
        self.client_address = client_address
        self.server = server
        self.setup()
        try:
            self.handle()
        finally:
            self.finish()

    def setup(self):
        pass

    def handle(self):
        pass

    def finish(self):
        pass


# The following two classes make it possible to use the same service
# class for stream or datagram servers.
# Each class sets up these instance variables:
# - rfile: a file object from which receives the request is read
# - wfile: a file object to which the reply is written
# When the handle() method returns, wfile is flushed properly


class StreamRequestHandler(BaseRequestHandler):

    """Define self.rfile and self.wfile for stream sockets."""

    # Default buffer sizes for rfile, wfile.
    # We default rfile to buffered because otherwise it could be
    # really slow for large data (a getc() call per byte); we make
    # wfile unbuffered because (a) often after a write() we want to
    # read and we need to flush the line; (b) big writes to unbuffered
    # files are typically optimized by stdio even when big reads
    # aren't.
    rbufsize = -1
    wbufsize = 0

    # A timeout to apply to the request socket, if not None.
    timeout = None

    # Disable nagle algorithm for this socket, if True.
    # Use only when wbufsize != 0, to avoid small packets.
    disable_nagle_algorithm = False

    def setup(self):
        self.connection = self.request
        if self.timeout is not None:
            self.connection.settimeout(self.timeout)
        if self.disable_nagle_algorithm:
            self.connection.setsockopt(socket.IPPROTO_TCP,
                                       socket.TCP_NODELAY, True)
        self.rfile = self.connection.makefile('rb', self.rbufsize)
        if self.wbufsize == 0:
            self.wfile = _SocketWriter(self.connection)
        else:
            self.wfile = self.connection.makefile('wb', self.wbufsize)

    def finish(self):
        if not self.wfile.closed:
            try:
                self.wfile.flush()
            except socket.error:
                # A final socket error may have occurred here, such as
                # the local error ECONNABORTED.
                pass
        self.wfile.close()
        self.rfile.close()

class _SocketWriter(BufferedIOBase):
    """Simple writable BufferedIOBase implementation for a socket

    Does not hold data in a buffer, avoiding any need to call flush()."""

    def __init__(self, sock):
        self._sock = sock

    def writable(self):
        return True

    def write(self, b):
        self._sock.sendall(b)
        with memoryview(b) as view:
            return view.nbytes

    def fileno(self):
        return self._sock.fileno()

class DatagramRequestHandler(BaseRequestHandler):

    """Define self.rfile and self.wfile for datagram sockets."""

    def setup(self):
        from io import BytesIO
        self.packet, self.socket = self.request
        self.rfile = BytesIO(self.packet)
        self.wfile = BytesIO()

    def finish(self):
        self.socket.sendto(self.wfile.getvalue(), self.client_address)