cpython/Modules/socketmodule.c

/***********************************************************
Copyright 1991, 1992, 1993, 1994 by Stichting Mathematisch Centrum,
Amsterdam, The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in 
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior permission.

STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

******************************************************************/

/* Socket module */

/*
This module provides an interface to Berkeley socket IPC.

Limitations:

- only AF_INET and AF_UNIX address families are supported
- no asynchronous I/O (but you can use select() on sockets)
- no read/write operations (use send/recv or makefile instead)
- setsockopt() and getsockopt() only support integer options

Interface:

- socket.gethostname() --> host name (string)
- socket.gethostbyname(hostname) --> host IP address (string: 'dd.dd.dd.dd')
- socket.getservbyname(servername, protocolname) --> port number
- socket.socket(family, type [, proto]) --> new socket object
- family and type constants from <socket.h> are accessed as socket.AF_INET etc.
- errors are reported as the exception socket.error
- an Internet socket address is a pair (hostname, port)
  where hostname can be anything recognized by gethostbyname()
  (including the dd.dd.dd.dd notation) and port is in host byte order
- where a hostname is returned, the dd.dd.dd.dd notation is used
- a UNIX domain socket is a string specifying the pathname

Socket methods:

- s.accept() --> new socket object, sockaddr
- s.setsockopt(level, optname, flag) --> Py_None
- s.getsockopt(level, optname) --> flag
- s.bind(sockaddr) --> Py_None
- s.connect(sockaddr) --> Py_None
- s.getsockname() --> sockaddr
- s.getpeername() --> sockaddr
- s.listen(n) --> Py_None
- s.makefile(mode) --> file object
- s.recv(nbytes [,flags]) --> string
- s.recvfrom(nbytes [,flags]) --> string, sockaddr
- s.send(string [,flags]) --> nbytes
- s.sendto(string, [flags,] sockaddr) --> nbytes
- s.setblocking(1 | 0) --> Py_None
- s.shutdown(how) --> Py_None
- s.close() --> Py_None

*/

#include "Python.h"

#include <sys/types.h>
#include "mytime.h"

#include <signal.h>
#ifndef NT
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#else
#include <winsock.h>
#endif
#ifdef HAVE_SYS_UN_H
#include <sys/un.h>
#else
#undef AF_UNIX
#endif

/* Here we have some hacks to choose between K&R or ANSI style function
   definitions.  For NT to build this as an extension module (ie, DLL)
   it must be compiled by the C++ compiler, as it takes the address of
   a static data item exported from the main Python DLL.
*/
#ifdef NT
/* seem to be a few differences in the API */
#define close closesocket
#define NO_DUP	/* I wont trust passing a socket to NT's RTL!!  */
#define FORCE_ANSI_FUNC_DEFS
#endif

#ifdef FORCE_ANSI_FUNC_DEFS
#define BUILD_FUNC_DEF_1( fnname, arg1type, arg1name )	\
fnname( arg1type arg1name )

#define BUILD_FUNC_DEF_2( fnname, arg1type, arg1name, arg2type, arg2name ) \
fnname( arg1type arg1name, arg2type arg2name )

#define BUILD_FUNC_DEF_3( fnname, arg1type, arg1name, arg2type, arg2name , arg3type, arg3name )	\
fnname( arg1type arg1name, arg2type arg2name, arg3type arg3name )

#define BUILD_FUNC_DEF_4( fnname, arg1type, arg1name, arg2type, arg2name , arg3type, arg3name, arg4type, arg4name )	\
fnname( arg1type arg1name, arg2type arg2name, arg3type arg3name, arg4type arg4name )

#else /* !FORCE_ANSI_FN_DEFS */
#define BUILD_FUNC_DEF_1( fnname, arg1type, arg1name )	\
fnname( arg1name )	\
	arg1type arg1name;

#define BUILD_FUNC_DEF_2( fnname, arg1type, arg1name, arg2type, arg2name ) \
fnname( arg1name, arg2name )	\
	arg1type arg1name;	\
	arg2type arg2name;

#define BUILD_FUNC_DEF_3( fnname, arg1type, arg1name, arg2type, arg2name, arg3type, arg3name ) \
fnname( arg1name, arg2name, arg3name )	\
	arg1type arg1name;	\
	arg2type arg2name;	\
	arg3type arg3name;

#define BUILD_FUNC_DEF_4( fnname, arg1type, arg1name, arg2type, arg2name, arg3type, arg3name, arg4type, arg4name ) \
fnname( arg1name, arg2name, arg3name, arg4name )	\
	arg1type arg1name;	\
	arg2type arg2name;	\
	arg3type arg3name;	\
	arg4type arg4name;

#endif /* !FORCE_ANSI_FN_DEFS */

/* Global variable holding the exception type for errors detected
   by this module (but not argument type or memory errors, etc.). */

static PyObject *PySocket_Error;


/* Convenience function to raise an error according to errno
   and return a NULL pointer from a function. */

static PyObject *
PySocket_Err()
{
#ifdef NT
	if (WSAGetLastError()) {
		PyObject *v;
		v = Py_BuildValue("(is)", WSAGetLastError(), "winsock error");
		if (v != NULL) {
			PyErr_SetObject(PySocket_Error, v);
			Py_DECREF(v);
		}
		return NULL;
	}
	else
#endif
	return PyErr_SetFromErrno(PySocket_Error);
}


/* The object holding a socket.  It holds some extra information,
   like the address family, which is used to decode socket address
   arguments properly. */

typedef struct {
	PyObject_HEAD
	int sock_fd;		/* Socket file descriptor */
	int sock_family;	/* Address family, e.g., AF_INET */
	int sock_type;		/* Socket type, e.g., SOCK_STREAM */
	int sock_proto;		/* Protocol type, usually 0 */
} PySocketSockObject;


/* A forward reference to the Socktype type object.
   The Socktype variable contains pointers to various functions,
   some of which call newsockobject(), which uses Socktype, so
   there has to be a circular reference. */

staticforward PyTypeObject PySocketSock_Type;


/* Create a new socket object.
   This just creates the object and initializes it.
   If the creation fails, return NULL and set an exception (implicit
   in NEWOBJ()). */

static PySocketSockObject *
BUILD_FUNC_DEF_4(PySocketSock_New, int, fd, int, family, int, type, int, proto)
{
	PySocketSockObject *s;
	s = PyObject_NEW(PySocketSockObject, &PySocketSock_Type);
	if (s != NULL) {
		s->sock_fd = fd;
		s->sock_family = family;
		s->sock_type = type;
		s->sock_proto = proto;
	}
	return s;
}


/* Convert a string specifying a host name or one of a few symbolic
   names to a numeric IP address.  This usually calls gethostbyname()
   to do the work; the names "" and "<broadcast>" are special.
   Return the length (should always be 4 bytes), or negative if
   an error occurred; then an exception is raised. */

static int
BUILD_FUNC_DEF_2(setipaddr, char*, name, struct sockaddr_in *, addr_ret)
{
	struct hostent *hp;
	int d1, d2, d3, d4;
	char ch;

	if (name[0] == '\0') {
		addr_ret->sin_addr.s_addr = INADDR_ANY;
		return 4;
	}
	if (name[0] == '<' && strcmp(name, "<broadcast>") == 0) {
		addr_ret->sin_addr.s_addr = INADDR_BROADCAST;
		return 4;
	}
	if (sscanf(name, "%d.%d.%d.%d%c", &d1, &d2, &d3, &d4, &ch) == 4 &&
	    0 <= d1 && d1 <= 255 && 0 <= d2 && d2 <= 255 &&
	    0 <= d3 && d3 <= 255 && 0 <= d4 && d4 <= 255) {
		addr_ret->sin_addr.s_addr = htonl(
			((long) d1 << 24) | ((long) d2 << 16) |
			((long) d3 << 8) | ((long) d4 << 0));
		return 4;
	}
	Py_BEGIN_ALLOW_THREADS
	hp = gethostbyname(name);
	Py_END_ALLOW_THREADS
	if (hp == NULL) {
		PyErr_SetString(PySocket_Error, "host not found");
		return -1;
	}
	memcpy((char *) &addr_ret->sin_addr, hp->h_addr, hp->h_length);
	return hp->h_length;
}


/* Create a string object representing an IP address.
   This is always a string of the form 'dd.dd.dd.dd' (with variable
   size numbers). */

static PyObject *
BUILD_FUNC_DEF_1(makeipaddr, struct sockaddr_in *,addr)
{
	long x = ntohl(addr->sin_addr.s_addr);
	char buf[100];
	sprintf(buf, "%d.%d.%d.%d",
		(int) (x>>24) & 0xff, (int) (x>>16) & 0xff,
		(int) (x>> 8) & 0xff, (int) (x>> 0) & 0xff);
	return PyString_FromString(buf);
}


/* Create an object representing the given socket address,
   suitable for passing it back to bind(), connect() etc.
   The family field of the sockaddr structure is inspected
   to determine what kind of address it really is. */

/*ARGSUSED*/
static PyObject *
BUILD_FUNC_DEF_2(makesockaddr,struct sockaddr *, addr, int, addrlen)
{
	if (addrlen == 0) {
		/* No address -- may be recvfrom() from known socket */
		Py_INCREF(Py_None);
		return Py_None;
	}

	switch (addr->sa_family) {

	case AF_INET:
	{
		struct sockaddr_in *a = (struct sockaddr_in *) addr;
		PyObject *addr = makeipaddr(a);
		PyObject *ret = Py_BuildValue("Oi", addr, ntohs(a->sin_port));
		Py_XDECREF(addr);
		return ret;
	}

#ifdef AF_UNIX
	case AF_UNIX:
	{
		struct sockaddr_un *a = (struct sockaddr_un *) addr;
		return PyString_FromString(a->sun_path);
	}
#endif /* AF_UNIX */

	/* More cases here... */

	default:
		PyErr_SetString(PySocket_Error, "return unknown socket address type");
		return NULL;

	}
}


/* Parse a socket address argument according to the socket object's
   address family.  Return 1 if the address was in the proper format,
   0 of not.  The address is returned through addr_ret, its length
   through len_ret. */

static int
BUILD_FUNC_DEF_4(
getsockaddrarg,PySocketSockObject *,s, PyObject *,args, struct sockaddr **,addr_ret, int *,len_ret)
{
	switch (s->sock_family) {

#ifdef AF_UNIX
	case AF_UNIX:
	{
		static struct sockaddr_un addr;
		char *path;
		int len;
		if (!PyArg_Parse(args, "s#", &path, &len))
			return 0;
		if (len > sizeof addr.sun_path) {
			PyErr_SetString(PySocket_Error, "AF_UNIX path too long");
			return 0;
		}
		addr.sun_family = AF_UNIX;
		memcpy(addr.sun_path, path, len);
		*addr_ret = (struct sockaddr *) &addr;
		*len_ret = len + sizeof addr.sun_family;
		return 1;
	}
#endif /* AF_UNIX */

	case AF_INET:
	{
		static struct sockaddr_in addr;
		char *host;
		int port;
		if (!PyArg_Parse(args, "(si)", &host, &port))
			return 0;
		if (setipaddr(host, &addr) < 0)
			return 0;
		addr.sin_family = AF_INET;
		addr.sin_port = htons(port);
		*addr_ret = (struct sockaddr *) &addr;
		*len_ret = sizeof addr;
		return 1;
	}

	/* More cases here... */

	default:
		PyErr_SetString(PySocket_Error, "getsockaddrarg: bad family");
		return 0;

	}
}


/* Get the address length according to the socket object's address family. 
   Return 1 if the family is known, 0 otherwise.  The length is returned
   through len_ret. */

static int
BUILD_FUNC_DEF_2(getsockaddrlen,PySocketSockObject *,s, int *,len_ret)
{
	switch (s->sock_family) {

#ifdef AF_UNIX
	case AF_UNIX:
	{
		*len_ret = sizeof (struct sockaddr_un);
		return 1;
	}
#endif /* AF_UNIX */

	case AF_INET:
	{
		*len_ret = sizeof (struct sockaddr_in);
		return 1;
	}

	/* More cases here... */

	default:
		PyErr_SetString(PySocket_Error, "getsockaddrarg: bad family");
		return 0;

	}
}


/* s.accept() method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_accept,PySocketSockObject *,s, PyObject *,args)
{
	char addrbuf[256];
	int addrlen, newfd;
	PyObject *sock, *addr, *res;
	if (!PyArg_NoArgs(args))
		return NULL;
	if (!getsockaddrlen(s, &addrlen))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	newfd = accept(s->sock_fd, (struct sockaddr *) addrbuf, &addrlen);
	Py_END_ALLOW_THREADS
	if (newfd < 0)
		return PySocket_Err();
	/* Create the new object with unspecified family,
	   to avoid calls to bind() etc. on it. */
	sock = (PyObject *) PySocketSock_New(newfd,
					s->sock_family,
					s->sock_type,
					s->sock_proto);
	if (sock == NULL)
		close(newfd);
	addr = makesockaddr((struct sockaddr *) addrbuf, addrlen);
	res = Py_BuildValue("OO", sock, addr);
	Py_XDECREF(sock);
	Py_XDECREF(addr);
	return res;
}


#if 0
/* s.allowbroadcast() method */
/* XXX obsolete -- will disappear in next release */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_allowbroadcast,PySocketSockObject *,s, PyObject *,args)
{
	int flag;
	int res;
	if (!PyArg_Parse(args, "i", &flag))
		return NULL;
	res = setsockopt(s->sock_fd, SOL_SOCKET, SO_BROADCAST,
			 (ANY *)&flag, sizeof flag);
	if (res < 0)
		return PySocket_Err();
	Py_INCREF(Py_None);
	return Py_None;
}
#endif


#ifndef NT

/* s.setblocking(1 | 0) method */

static PyObject *
PySocketSock_setblocking(s, args)
	PySocketSockObject *s;
	PyObject *args;
{
	int block;
	int delay_flag;
	if (!PyArg_GetInt(args, &block))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	delay_flag = fcntl (s->sock_fd, F_GETFL, 0);
	if (block)
		delay_flag &= (~O_NDELAY);
	else
		delay_flag |= O_NDELAY;
	fcntl (s->sock_fd, F_SETFL, delay_flag);
	Py_END_ALLOW_THREADS

	Py_INCREF(Py_None);
	return Py_None;
}
#endif


/* s.setsockopt() method.
   With an integer third argument, sets an integer option.
   With a string third argument, sets an option from a buffer;
   use optional built-in module 'struct' to encode the string. */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_setsockopt,PySocketSockObject *,s, PyObject *,args)
{
	int level;
	int optname;
	int res;
	char *buf;
	int buflen;
	int flag;

	if (PyArg_Parse(args, "(iii)", &level, &optname, &flag)) {
		buf = (char *) &flag;
		buflen = sizeof flag;
	}
	else {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(iis#)", &level, &optname, &buf, &buflen))
			return NULL;
	}
	res = setsockopt(s->sock_fd, level, optname, (ANY *)buf, buflen);
	if (res < 0)
		return PySocket_Err();
	Py_INCREF(Py_None);
	return Py_None;
}


/* s.getsockopt() method.
   With two arguments, retrieves an integer option.
   With a third integer argument, retrieves a string buffer of that size;
   use optional built-in module 'struct' to decode the string. */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_getsockopt,PySocketSockObject *,s, PyObject *,args)
{
	int level;
	int optname;
	int res;
	PyObject *buf;
	int buflen;
	int flag;

	if (PyArg_Parse(args, "(ii)", &level, &optname)) {
		int flag = 0;
		int flagsize = sizeof flag;
		res = getsockopt(s->sock_fd, level, optname,
				 (ANY *)&flag, &flagsize);
		if (res < 0)
			return PySocket_Err();
		return PyInt_FromLong(flag);
	}
	PyErr_Clear();
	if (!PyArg_Parse(args, "(iii)", &level, &optname, &buflen))
		return NULL;
	if (buflen <= 0 || buflen > 1024) {
		PyErr_SetString(PySocket_Error, "getsockopt buflen out of range");
		return NULL;
	}
	buf = PyString_FromStringAndSize((char *)NULL, buflen);
	if (buf == NULL)
		return NULL;
	res = getsockopt(s->sock_fd, level, optname,
			 (ANY *)getstringvalue(buf), &buflen);
	if (res < 0) {
		Py_DECREF(buf);
		return PySocket_Err();
	}
	_PyString_Resize(&buf, buflen);
	return buf;
}


/* s.bind(sockaddr) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_bind,PySocketSockObject *,s, PyObject *,args)
{
	struct sockaddr *addr;
	int addrlen;
	int res;
	if (!getsockaddrarg(s, args, &addr, &addrlen))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = bind(s->sock_fd, addr, addrlen);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	Py_INCREF(Py_None);
	return Py_None;
}


/* s.close() method.
   Set the file descriptor to -1 so operations tried subsequently
   will surely fail. */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_close,PySocketSockObject *,s, PyObject *,args)
{
	if (!PyArg_NoArgs(args))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	(void) close(s->sock_fd);
	Py_END_ALLOW_THREADS
	s->sock_fd = -1;
	Py_INCREF(Py_None);
	return Py_None;
}


/* s.connect(sockaddr) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_connect,PySocketSockObject *,s, PyObject *,args)
{
	struct sockaddr *addr;
	int addrlen;
	int res;
	if (!getsockaddrarg(s, args, &addr, &addrlen))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = connect(s->sock_fd, addr, addrlen);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	Py_INCREF(Py_None);
	return Py_None;
}


/* s.fileno() method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_fileno,PySocketSockObject *,s, PyObject *,args)
{
	if (!PyArg_NoArgs(args))
		return NULL;
	return PyInt_FromLong((long) s->sock_fd);
}


/* s.getsockname() method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_getsockname,PySocketSockObject *,s, PyObject *,args)
{
	char addrbuf[256];
	int addrlen, res;
	if (!PyArg_NoArgs(args))
		return NULL;
	if (!getsockaddrlen(s, &addrlen))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = getsockname(s->sock_fd, (struct sockaddr *) addrbuf, &addrlen);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	return makesockaddr((struct sockaddr *) addrbuf, addrlen);
}


#ifdef HAVE_GETPEERNAME		/* Cray APP doesn't have this :-( */
/* s.getpeername() method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_getpeername,PySocketSockObject *,s, PyObject *,args)
{
	char addrbuf[256];
	int addrlen, res;
	if (!PyArg_NoArgs(args))
		return NULL;
	if (!getsockaddrlen(s, &addrlen))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = getpeername(s->sock_fd, (struct sockaddr *) addrbuf, &addrlen);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	return makesockaddr((struct sockaddr *) addrbuf, addrlen);
}
#endif /* HAVE_GETPEERNAME */


/* s.listen(n) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_listen,PySocketSockObject *,s, PyObject *,args)
{
	int backlog;
	int res;
	if (!PyArg_GetInt(args, &backlog))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	if (backlog < 1)
		backlog = 1;
	res = listen(s->sock_fd, backlog);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	Py_INCREF(Py_None);
	return Py_None;
}

#ifndef NO_DUP
/* s.makefile(mode) method.
   Create a new open file object referring to a dupped version of
   the socket's file descriptor.  (The dup() call is necessary so
   that the open file and socket objects may be closed independent
   of each other.)
   The mode argument specifies 'r' or 'w' passed to fdopen(). */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_makefile,PySocketSockObject *,s, PyObject *,args)
{
	extern int fclose PROTO((FILE *));
	char *mode;
	int fd;
	FILE *fp;
	if (!PyArg_Parse(args, "s", &mode))
		return NULL;
	if ((fd = dup(s->sock_fd)) < 0 ||
	    (fp = fdopen(fd, mode)) == NULL)
		return PySocket_Err();
	return PyFile_FromFile(fp, "<socket>", mode, fclose);
}
#endif /* NO_DUP */

/* s.recv(nbytes [,flags]) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_recv,PySocketSockObject *,s, PyObject *,args)
{
	int len, n, flags;
	PyObject *buf;
	flags = 0;
	if (!PyArg_Parse(args, "i", &len)) {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(ii)", &len, &flags))
			return NULL;
	}
	buf = PyString_FromStringAndSize((char *) 0, len);
	if (buf == NULL)
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	n = recv(s->sock_fd, getstringvalue(buf), len, flags);
	Py_END_ALLOW_THREADS
	if (n < 0)
		return PySocket_Err();
	if (_PyString_Resize(&buf, n) < 0)
		return NULL;
	return buf;
}


/* s.recvfrom(nbytes [,flags]) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_recvfrom,PySocketSockObject *,s, PyObject *,args)
{
	char addrbuf[256];
	PyObject *buf, *addr, *ret;
	int addrlen, len, n, flags;
	flags = 0;
	if (!PyArg_Parse(args, "i", &len)) {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(ii)", &len, &flags))
		    return NULL;
	}
	if (!getsockaddrlen(s, &addrlen))
		return NULL;
	buf = PyString_FromStringAndSize((char *) 0, len);
	if (buf == NULL)
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	n = recvfrom(s->sock_fd, PyString_AsString(buf), len, flags,
#ifndef NT
		     (ANY *)addrbuf, &addrlen);
#else
     		     (struct sockaddr *)addrbuf, &addrlen);
#endif
	Py_END_ALLOW_THREADS
	if (n < 0)
		return PySocket_Err();
	if (_PyString_Resize(&buf, n) < 0)
		return NULL;
	addr = makesockaddr((struct sockaddr *)addrbuf, addrlen);
	ret = Py_BuildValue("OO", buf, addr);
	Py_XDECREF(addr);
	Py_XDECREF(buf);
	return ret;
}


/* s.send(data [,flags]) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_send,PySocketSockObject *,s, PyObject *,args)
{
	char *buf;
	int len, n, flags;
	flags = 0;
	if (!PyArg_Parse(args, "s#", &buf, &len)) {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(s#i)", &buf, &len, &flags))
			return NULL;
	}
	Py_BEGIN_ALLOW_THREADS
	n = send(s->sock_fd, buf, len, flags);
	Py_END_ALLOW_THREADS
	if (n < 0)
		return PySocket_Err();
	return PyInt_FromLong((long)n);
}


/* s.sendto(data, [flags,] sockaddr) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_sendto,PySocketSockObject *,s, PyObject *,args)
{
	PyObject *addro;
	char *buf;
	struct sockaddr *addr;
	int addrlen, len, n, flags;
	flags = 0;
	if (!PyArg_Parse(args, "(s#O)", &buf, &len, &addro)) {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(s#iO)", &buf, &len, &flags, &addro))
			return NULL;
	}
	if (!getsockaddrarg(s, addro, &addr, &addrlen))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	n = sendto(s->sock_fd, buf, len, flags, addr, addrlen);
	Py_END_ALLOW_THREADS
	if (n < 0)
		return PySocket_Err();
	return PyInt_FromLong((long)n);
}


/* s.shutdown(how) method */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_shutdown,PySocketSockObject *,s, PyObject *,args)
{
	int how;
	int res;
	if (!PyArg_GetInt(args, &how))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = shutdown(s->sock_fd, how);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	Py_INCREF(Py_None);
	return Py_None;
}


/* List of methods for socket objects */

static PyMethodDef PySocketSock_methods[] = {
	{"accept",		(PyCFunction)PySocketSock_accept},
#if 0
	{"allowbroadcast",	(PyCFunction)PySocketSock_allowbroadcast},
#endif
#ifndef NT
	{"setblocking",         (PyCFunction)PySocketSock_setblocking},
#endif
	{"setsockopt",		(PyCFunction)PySocketSock_setsockopt},
	{"getsockopt",		(PyCFunction)PySocketSock_getsockopt},
	{"bind",		(PyCFunction)PySocketSock_bind},
	{"close",		(PyCFunction)PySocketSock_close},
	{"connect",		(PyCFunction)PySocketSock_connect},
	{"fileno",		(PyCFunction)PySocketSock_fileno},
	{"getsockname",		(PyCFunction)PySocketSock_getsockname},
#ifdef HAVE_GETPEERNAME
	{"getpeername",		(PyCFunction)PySocketSock_getpeername},
#endif
	{"listen",		(PyCFunction)PySocketSock_listen},
#ifndef NO_DUP
	{"makefile",		(PyCFunction)PySocketSock_makefile},
#endif
	{"recv",		(PyCFunction)PySocketSock_recv},
	{"recvfrom",		(PyCFunction)PySocketSock_recvfrom},
	{"send",		(PyCFunction)PySocketSock_send},
	{"sendto",		(PyCFunction)PySocketSock_sendto},
	{"shutdown",		(PyCFunction)PySocketSock_shutdown},
	{NULL,			NULL}		/* sentinel */
};


/* Deallocate a socket object in response to the last Py_DECREF().
   First close the file description. */

static void
BUILD_FUNC_DEF_1(PySocketSock_dealloc, PySocketSockObject *,s)
{
	(void) close(s->sock_fd);
	PyMem_DEL(s);
}


/* Return a socket object's named attribute. */

static PyObject *
BUILD_FUNC_DEF_2(PySocketSock_getattr,PySocketSockObject *,s, char *,name)
{
	return Py_FindMethod(PySocketSock_methods, (PyObject *) s, name);
}


/* Type object for socket objects. */

static PyTypeObject PySocketSock_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"socket",
	sizeof(PySocketSockObject),
	0,
	(destructor)PySocketSock_dealloc, /*tp_dealloc*/
	0,		/*tp_print*/
	(getattrfunc)PySocketSock_getattr, /*tp_getattr*/
	0,		/*tp_setattr*/
	0,		/*tp_compare*/
	0,		/*tp_repr*/
	0,		/*tp_as_number*/
	0,		/*tp_as_sequence*/
	0,		/*tp_as_mapping*/
};


/* Python interface to gethostname(). */

/*ARGSUSED*/
static PyObject *
BUILD_FUNC_DEF_2(PySocket_gethostname,PyObject *,self, PyObject *,args)
{
	char buf[1024];
	int res;
	if (!PyArg_NoArgs(args))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = gethostname(buf, (int) sizeof buf - 1);
	Py_END_ALLOW_THREADS
	if (res < 0)
		return PySocket_Err();
	buf[sizeof buf - 1] = '\0';
	return PyString_FromString(buf);
}


/* Python interface to gethostbyname(name). */

/*ARGSUSED*/
static PyObject *
BUILD_FUNC_DEF_2(PySocket_gethostbyname,PyObject *,self, PyObject *,args)
{
	char *name;
	struct sockaddr_in addrbuf;
	if (!PyArg_Parse(args, "s", &name))
		return NULL;
	if (setipaddr(name, &addrbuf) < 0)
		return NULL;
	return makeipaddr(&addrbuf);
}


/* Python interface to getservbyname(name).
   This only returns the port number, since the other info is already
   known or not useful (like the list of aliases). */

/*ARGSUSED*/
static PyObject *
BUILD_FUNC_DEF_2(PySocket_getservbyname,PyObject *,self, PyObject *,args)
{
	char *name, *proto;
	struct servent *sp;
	if (!PyArg_Parse(args, "(ss)", &name, &proto))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	sp = getservbyname(name, proto);
	Py_END_ALLOW_THREADS
	if (sp == NULL) {
		PyErr_SetString(PySocket_Error, "service/proto not found");
		return NULL;
	}
	return PyInt_FromLong((long) ntohs(sp->s_port));
}


/* Python interface to socket(family, type, proto).
   The third (protocol) argument is optional.
   Return a new socket object. */

/*ARGSUSED*/
static PyObject *
BUILD_FUNC_DEF_2(PySocket_socket,PyObject *,self,PyObject *,args)
{
	PySocketSockObject *s;
	int fd, family, type, proto;
	proto = 0;
	if (!PyArg_Parse(args, "(ii)", &family, &type)) {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(iii)", &family, &type, &proto))
			return NULL;
	}
	Py_BEGIN_ALLOW_THREADS
	fd = socket(family, type, proto);
	Py_END_ALLOW_THREADS
	if (fd < 0)
		return PySocket_Err();
	s = PySocketSock_New(fd, family, type, proto);
	/* If the object can't be created, don't forget to close the
	   file descriptor again! */
	if (s == NULL)
		(void) close(fd);
	/* From now on, ignore SIGPIPE and let the error checking
	   do the work. */
#ifdef SIGPIPE      
	(void) signal(SIGPIPE, SIG_IGN);
#endif   
	return (PyObject *) s;
}

#ifndef NO_DUP
/* Create a socket object from a numeric file description.
   Useful e.g. if stdin is a socket.
   Additional arguments as for socket(). */

/*ARGSUSED*/
static PyObject *
BUILD_FUNC_DEF_2(PySocket_fromfd,PyObject *,self,PyObject *,args)
{
	PySocketSockObject *s;
	int fd, family, type, proto;
	proto = 0;
	if (!PyArg_Parse(args, "(iii)", &fd, &family, &type)) {
		PyErr_Clear();
		if (!PyArg_Parse(args, "(iiii)", &fd, &family, &type, &proto))
			return NULL;
	}
	/* Dup the fd so it and the socket can be closed independently */
	fd = dup(fd);
	if (fd < 0)
		return PySocket_Err();
	s = PySocketSock_New(fd, family, type, proto);
	/* From now on, ignore SIGPIPE and let the error checking
	   do the work. */
#ifdef SIGPIPE      
	(void) signal(SIGPIPE, SIG_IGN);
#endif   
	return (PyObject *) s;
}
#endif /* NO_DUP */

/* List of functions exported by this module. */

static PyMethodDef PySocket_methods[] = {
	{"gethostbyname",	PySocket_gethostbyname},
	{"gethostname",		PySocket_gethostname},
	{"getservbyname",	PySocket_getservbyname},
	{"socket",		PySocket_socket},
#ifndef NO_DUP
	{"fromfd",		PySocket_fromfd},
#endif
	{NULL,			NULL}		 /* Sentinel */
};


/* Convenience routine to export an integer value.
   For simplicity, errors (which are unlikely anyway) are ignored. */

static void
BUILD_FUNC_DEF_3(insint,PyObject *,d,char *,name,int,value)
{
	PyObject *v = PyInt_FromLong((long) value);
	if (v == NULL) {
		/* Don't bother reporting this error */
		PyErr_Clear();
	}
	else {
		PyDict_SetItemString(d, name, v);
		Py_DECREF(v);
	}
}


/* Initialize this module.
   This is called when the first 'import socket' is done,
   via a table in config.c, if config.c is compiled with USE_SOCKET
   defined. */

void
initsocket()
{
	PyObject *m, *d;
	m = Py_InitModule("socket", PySocket_methods);
	d = PyModule_GetDict(m);
	PySocket_Error = PyString_FromString("socket.error");
	if (PySocket_Error == NULL || 
	    PyDict_SetItemString(d, "error", PySocket_Error) != 0)
		Py_FatalError("can't define socket.error");
	insint(d, "AF_INET", AF_INET);
#ifdef AF_UNIX
	insint(d, "AF_UNIX", AF_UNIX);
#endif /* AF_UNIX */
	insint(d, "SOCK_STREAM", SOCK_STREAM);
	insint(d, "SOCK_DGRAM", SOCK_DGRAM);
	insint(d, "SOCK_RAW", SOCK_RAW);
	insint(d, "SOCK_SEQPACKET", SOCK_SEQPACKET);
	insint(d, "SOCK_RDM", SOCK_RDM);
}

#ifdef NT
BOOL	WINAPI	DllMain (HANDLE hInst, 
			ULONG ul_reason_for_call,
			LPVOID lpReserved)
{
	switch (ul_reason_for_call)
	{
		case DLL_PROCESS_ATTACH:
			WSADATA WSAData;
			if (WSAStartup(MAKEWORD(2,0), &WSAData)) {
				OutputDebugString("Python can't initialize Windows Sockets DLL!");
				return FALSE;
			}
			break;
		case DLL_PROCESS_DETACH:
			WSACleanup();
			break;

	}
	return TRUE;
}
#endif /* NT */