sock.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

/*
 * UNIX		An implementation of the AF_UNIX network domain for the
 *		LINUX operating system.  UNIX is implemented using the
 *		BSD Socket interface as the means of communication with
 *		the user level.
 *
 * Version:	@(#)sock.c	1.0.5	05/25/93
 *
 * Authors:	Orest Zborowski, <[e-mail]>
 *		Ross Biro, <[e-mail]>
 *		Fred N. van Kempen, <[e-mail]>
 *
 * Fixes:
 *		Alan Cox	:	Verify Area
 *		NET2E Team	:	Page fault locks
 *	Dmitry Gorodchanin	:	/proc locking
 *
 * To Do:
 *	Some nice person is looking into Unix sockets done properly. NET3
 *	will replace all of this and include datagram sockets and socket
 *	options - so please stop asking me for them 8-)
 *
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or(at your option) any later version.
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/socket.h>
#include <linux/un.h>
#include <linux/fcntl.h>
#include <linux/termios.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/fs.h>
#include <linux/ddi.h>
#include <linux/malloc.h>

#include <asm/system.h>
#include <asm/segment.h>

#include <stdarg.h>

#include "unix.h"

struct unix_proto_data unix_datas[NSOCKETS];
static int unix_debug = 0;


static int unix_proto_create(struct socket *sock, int protocol);
static int unix_proto_dup(struct socket *newsock, struct socket *oldsock);
static int unix_proto_release(struct socket *sock, struct socket *peer);
static int unix_proto_bind(struct socket *sock, struct sockaddr *umyaddr,
			   int sockaddr_len);
static int unix_proto_connect(struct socket *sock, struct sockaddr *uservaddr,
			      int sockaddr_len, int flags);
static int unix_proto_socketpair(struct socket *sock1, struct socket *sock2);
static int unix_proto_accept(struct socket *sock, struct socket *newsock, 
			     int flags);
static int unix_proto_getname(struct socket *sock, struct sockaddr *usockaddr,
			      int *usockaddr_len, int peer);
static int unix_proto_read(struct socket *sock, char *ubuf, int size,
			   int nonblock);
static int unix_proto_write(struct socket *sock, char *ubuf, int size,
			    int nonblock);
static int unix_proto_select(struct socket *sock, int sel_type, select_table * wait);
static int unix_proto_ioctl(struct socket *sock, unsigned int cmd,
			    unsigned long arg);
static int unix_proto_listen(struct socket *sock, int backlog);
static int unix_proto_send(struct socket *sock, void *buff, int len,
			    int nonblock, unsigned flags);
static int unix_proto_recv(struct socket *sock, void *buff, int len,
			    int nonblock, unsigned flags);
static int unix_proto_sendto(struct socket *sock, void *buff, int len,
			      int nonblock, unsigned flags,
			      struct sockaddr *addr, int addr_len);
static int unix_proto_recvfrom(struct socket *sock, void *buff, int len,
				int nonblock, unsigned flags,
				struct sockaddr *addr, int *addr_len);

static int unix_proto_shutdown(struct socket *sock, int how);

static int unix_proto_setsockopt(struct socket *sock, int level, int optname,
				  char *optval, int optlen);
static int unix_proto_getsockopt(struct socket *sock, int level, int optname,
				  char *optval, int *optlen);


static void
dprintf(int level, char *fmt, ...)
{
  va_list args;
  char *buff;
  extern int vsprintf(char * buf, const char * fmt, va_list args);

  if (level != unix_debug) return;

  buff = (char *) kmalloc(256, GFP_KERNEL);
  if (buff != NULL) {
	va_start(args, fmt);
	vsprintf(buff, fmt, args);
	va_end(args);
	printk(buff);
	kfree(buff);
  }
}


static inline int
min(int a, int b)
{
  if (a < b) return(a);
  return(b);
}


void
sockaddr_un_printk(struct sockaddr_un *sockun, int sockaddr_len)
{
  char buf[sizeof(sockun->sun_path) + 1];

  if (unix_debug == 0) return;

  sockaddr_len -= UN_PATH_OFFSET;
  if (sockun->sun_family != AF_UNIX)
	printk("UNIX: Badd addr family %d>\n", sockun->sun_family);
    else if (sockaddr_len <= 0 || sockaddr_len >= sizeof(buf))
	printk("UNIX: Bad addr len %d>\n", sockaddr_len);
    else {
	memcpy(buf, sockun->sun_path, sockaddr_len);
	buf[sockaddr_len] = '\0';
	printk("\"%s\"[%lu]\n", buf, sockaddr_len + UN_PATH_OFFSET);
  }
}
  

/* Support routines doing anti page fault locking 
 * FvK & Matt Dillon (borrowed From NET2E3)
 */

/*
 * Locking for unix-domain sockets.  We don't use the socket structure's
 * wait queue because it is allowed to 'go away' outside of our control,
 * whereas unix_proto_data structures stick around.
 */
void unix_lock(struct unix_proto_data *upd)
{
	while (upd->lock_flag)
		sleep_on(&upd->wait);
	upd->lock_flag = 1;
}


void unix_unlock(struct unix_proto_data *upd)
{
	upd->lock_flag = 0;
	wake_up(&upd->wait);
}

/* don't have to do anything. */
static int
unix_proto_listen(struct socket *sock, int backlog)
{
  return(0);
}


static int
unix_proto_setsockopt(struct socket *sock, int level, int optname,
		      char *optval, int optlen)
{
  return(-EOPNOTSUPP);
}


static int
unix_proto_getsockopt(struct socket *sock, int level, int optname,
		      char *optval, int *optlen)
{
  return(-EOPNOTSUPP);
}

static int
unix_proto_sendto(struct socket *sock, void *buff, int len, int nonblock, 
		  unsigned flags,  struct sockaddr *addr, int addr_len)
{
  return(-EOPNOTSUPP);
}     

static int
unix_proto_recvfrom(struct socket *sock, void *buff, int len, int nonblock, 
		    unsigned flags, struct sockaddr *addr, int *addr_len)
{
  return(-EOPNOTSUPP);
}     


static int
unix_proto_shutdown(struct socket *sock, int how)
{
  return(-EOPNOTSUPP);
}


/* This error needs to be checked. */
static int
unix_proto_send(struct socket *sock, void *buff, int len, int nonblock,
		unsigned flags)
{
  if (flags != 0) return(-EINVAL);
  return(unix_proto_write(sock, (char *) buff, len, nonblock));
}


/* This error needs to be checked. */
static int
unix_proto_recv(struct socket *sock, void *buff, int len, int nonblock,
		unsigned flags)
{
  if (flags != 0) return(-EINVAL);
  return(unix_proto_read(sock, (char *) buff, len, nonblock));
}


static struct unix_proto_data *
unix_data_lookup(struct sockaddr_un *sockun, int sockaddr_len,
		 struct inode *inode)
{
  struct unix_proto_data *upd;

  for(upd = unix_datas; upd <= last_unix_data; ++upd) {
	if (upd->refcnt > 0 && upd->socket &&
	    upd->socket->state == SS_UNCONNECTED &&
	    upd->sockaddr_un.sun_family == sockun->sun_family &&
	    upd->inode == inode) return(upd);
  }
  return(NULL);
}


static struct unix_proto_data *
unix_data_alloc(void)
{
  struct unix_proto_data *upd;

  cli();
  for(upd = unix_datas; upd <= last_unix_data; ++upd) {
	if (!upd->refcnt) {
		upd->refcnt = -1;	/* unix domain socket not yet initialised - bgm */
		sti();
		upd->socket = NULL;
		upd->sockaddr_len = 0;
		upd->sockaddr_un.sun_family = 0;
		upd->buf = NULL;
		upd->bp_head = upd->bp_tail = 0;
		upd->inode = NULL;
		upd->peerupd = NULL;
		return(upd);
	}
  }
  sti();
  return(NULL);
}


static inline void
unix_data_ref(struct unix_proto_data *upd)
{
  if (!upd) {
    dprintf(1, "UNIX: data_ref: upd = NULL\n");
    return;
  }
  ++upd->refcnt;
  dprintf(1, "UNIX: data_ref: refing data 0x%x(%d)\n", upd, upd->refcnt);
}


static void
unix_data_deref(struct unix_proto_data *upd)
{
  if (!upd) {
    dprintf(1, "UNIX: data_deref: upd = NULL\n");
    return;
  }
  if (upd->refcnt == 1) {
	dprintf(1, "UNIX: data_deref: releasing data 0x%x\n", upd);
	if (upd->buf) {
		free_page((unsigned long)upd->buf);
		upd->buf = NULL;
		upd->bp_head = upd->bp_tail = 0;
	}
  }
  --upd->refcnt;
}


/*
 * Upon a create, we allocate an empty protocol data,
 * and grab a page to buffer writes.
 */
static int
unix_proto_create(struct socket *sock, int protocol)
{
  struct unix_proto_data *upd;

  dprintf(1, "UNIX: create: socket 0x%x, proto %d\n", sock, protocol);
  if (protocol != 0) {
	dprintf(1, "UNIX: create: protocol != 0\n");
	return(-EINVAL);
  }
  if (!(upd = unix_data_alloc())) {
	printk("UNIX: create: can't allocate buffer\n");
	return(-ENOMEM);
  }
  if (!(upd->buf = (char*) get_free_page(GFP_USER))) {
	printk("UNIX: create: can't get page!\n");
	unix_data_deref(upd);
	return(-ENOMEM);
  }
  upd->protocol = protocol;
  upd->socket = sock;
  UN_DATA(sock) = upd;
  upd->refcnt = 1;	/* Now its complete - bgm */
  dprintf(1, "UNIX: create: allocated data 0x%x\n", upd);
  return(0);
}


static int
unix_proto_dup(struct socket *newsock, struct socket *oldsock)
{
  struct unix_proto_data *upd = UN_DATA(oldsock);

  return(unix_proto_create(newsock, upd->protocol));
}


static int
unix_proto_release(struct socket *sock, struct socket *peer)
{
  struct unix_proto_data *upd = UN_DATA(sock);

  dprintf(1, "UNIX: release: socket 0x%x, unix_data 0x%x\n", sock, upd);
  if (!upd) return(0);
  if (upd->socket != sock) {
	printk("UNIX: release: socket link mismatch!\n");
	return(-EINVAL);
  }
  if (upd->inode) {
	dprintf(1, "UNIX: release: releasing inode 0x%x\n", upd->inode);
	iput(upd->inode);
	upd->inode = NULL;
  }
  UN_DATA(sock) = NULL;
  upd->socket = NULL;
  if (upd->peerupd) unix_data_deref(upd->peerupd);
  unix_data_deref(upd);
  return(0);
}


/*
 * Bind a name to a socket.
 * This is where much of the work is done: we allocate a fresh page for
 * the buffer, grab the appropriate inode and set things up.
 *
 * FIXME: what should we do if an address is already bound?
 *	  Here we return EINVAL, but it may be necessary to re-bind.
 *	  I think thats what BSD does in the case of datagram sockets...
 */
static int
unix_proto_bind(struct socket *sock, struct sockaddr *umyaddr,
		int sockaddr_len)
{
  char fname[sizeof(((struct sockaddr_un *)0)->sun_path) + 1];
  struct unix_proto_data *upd = UN_DATA(sock);
  unsigned long old_fs;
  int i;
  int er;

  dprintf(1, "UNIX: bind: socket 0x%x, len=%d\n", sock, sockaddr_len);
  if (sockaddr_len <= UN_PATH_OFFSET ||
      sockaddr_len > sizeof(struct sockaddr_un)) {
	dprintf(1, "UNIX: bind: bad length %d\n", sockaddr_len);
	return(-EINVAL);
  }
  if (upd->sockaddr_len || upd->inode) {
	printk("UNIX: bind: already bound!\n");
	return(-EINVAL);
  }
  er=verify_area(VERIFY_WRITE, umyaddr, sockaddr_len);
  if(er)
  	return er;
  memcpy_fromfs(&upd->sockaddr_un, umyaddr, sockaddr_len);
  upd->sockaddr_un.sun_path[sockaddr_len-UN_PATH_OFFSET] = '\0';
  if (upd->sockaddr_un.sun_family != AF_UNIX) {
	dprintf(1, "UNIX: bind: family is %d, not AF_UNIX(%d)\n",
	       			upd->sockaddr_un.sun_family, AF_UNIX);
	return(-EINVAL);
  }

  memcpy(fname, upd->sockaddr_un.sun_path, sockaddr_len-UN_PATH_OFFSET);
  fname[sockaddr_len-UN_PATH_OFFSET] = '\0';
  old_fs = get_fs();
  set_fs(get_ds());
  i = do_mknod(fname, S_IFSOCK | S_IRWXUGO, 0);
  if (i == 0) i = open_namei(fname, 0, S_IFSOCK, &upd->inode, NULL);
  set_fs(old_fs);
  if (i < 0) {
	printk("UNIX: bind: can't open socket %s\n", fname);
	return(i);
  }
  upd->sockaddr_len = sockaddr_len;	/* now its legal */

  dprintf(1, "UNIX: bind: bound socket address: ");
  sockaddr_un_printk(&upd->sockaddr_un, upd->sockaddr_len);
  dprintf(1, "to inode 0x%x\n", upd->inode);
  return(0);
}


/*
 * Perform a connection. we can only connect to unix sockets
 * (I can't for the life of me find an application where that
 * wouldn't be the case!)
 */
static int
unix_proto_connect(struct socket *sock, struct sockaddr *uservaddr,
		   int sockaddr_len, int flags)
{
  char fname[sizeof(((struct sockaddr_un *)0)->sun_path) + 1];
  struct sockaddr_un sockun;
  struct unix_proto_data *serv_upd;
  struct inode *inode;
  unsigned long old_fs;
  int i;
  int er;

  dprintf(1, "UNIX: connect: socket 0x%x, servlen=%d\n", sock, sockaddr_len);

  if (sockaddr_len <= UN_PATH_OFFSET ||
      sockaddr_len > sizeof(struct sockaddr_un)) {
	dprintf(1, "UNIX: connect: bad length %d\n", sockaddr_len);
	return(-EINVAL);
  }
  if (sock->state == SS_CONNECTING) return(-EINPROGRESS);
  if (sock->state == SS_CONNECTED) return(-EISCONN);

  er=verify_area(VERIFY_READ, uservaddr, sockaddr_len);
  if(er)
  	return er;
  memcpy_fromfs(&sockun, uservaddr, sockaddr_len);
  sockun.sun_path[sockaddr_len-UN_PATH_OFFSET] = '\0';
  if (sockun.sun_family != AF_UNIX) {
	dprintf(1, "UNIX: connect: family is %d, not AF_UNIX(%d)\n",
	       					sockun.sun_family, AF_UNIX);
	return(-EINVAL);
  }

  /*
   * Try to open the name in the filesystem - this is how we
   * identify ourselves and our server. Note that we don't
   * hold onto the inode that long, just enough to find our
   * server. When we're connected, we mooch off the server.
   */