sock.c

嵌入式系统设计与实例开发实验教材二源码 多线程应用程序设计 串行端口程序设计 AD接口实验 CAN总线通信实验 GPS通信实验 Linux内核移植与编译实验 IC卡读写实验 SD驱动使

/*
 *  sock.c
 *
 *  Copyright (C) 1995, 1996 by Paal-Kr. Engstad and Volker Lendecke
 *  Copyright (C) 1997 by Volker Lendecke
 *
 *  Please add a note about your changes to smbfs in the ChangeLog file.
 */

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/socket.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/in.h>
#include <linux/net.h>
#include <linux/mm.h>
#include <linux/netdevice.h>
#include <linux/smp_lock.h>
#include <net/scm.h>
#include <net/ip.h>

#include <linux/smb_fs.h>
#include <linux/smb.h>
#include <linux/smbno.h>

#include <asm/uaccess.h>

#include "smb_debug.h"
#include "proto.h"


static int
_recvfrom(struct socket *socket, unsigned char *ubuf, int size,
	  unsigned flags)
{
	struct iovec iov;
	struct msghdr msg;
	struct scm_cookie scm;

	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = NULL;
	iov.iov_base = ubuf;
	iov.iov_len = size;
	
	memset(&scm, 0,sizeof(scm));
	size=socket->ops->recvmsg(socket, &msg, size, flags, &scm);
	if(size>=0)
		scm_recv(socket,&msg,&scm,flags);
	return size;
}

static int
_send(struct socket *socket, const void *buff, int len)
{
	struct iovec iov;
	struct msghdr msg;
	struct scm_cookie scm;
	int err;

	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	
	iov.iov_base = (void *)buff;
	iov.iov_len = len;

	msg.msg_flags = 0;

	err = scm_send(socket, &msg, &scm);
        if (err >= 0)
	{
		err = socket->ops->sendmsg(socket, &msg, len, &scm);
		scm_destroy(&scm);
	}
	return err;
}

struct data_callback {
	struct tq_struct cb;
	struct sock *sk;
};
/*
 * N.B. What happens if we're in here when the socket closes??
 */
static void
found_data(struct sock *sk)
{
	/*
	 * FIXME: copied from sock_def_readable, it should be a call to
	 * server->data_ready()	-- [e-mail]
	 */
	read_lock(&sk->callback_lock);
	if(!sk->dead) {
		wake_up_interruptible(sk->sleep);
		sock_wake_async(sk->socket,1,POLL_IN);
	}
	read_unlock(&sk->callback_lock);
}

static void
smb_data_callback(void* ptr)
{
	struct data_callback* job=ptr;
	struct socket *socket = job->sk->socket;
	unsigned char peek_buf[4];
	int result = 0;
	mm_segment_t fs;
	int count = 100;   /* this is a lot, we should have some data waiting */
	int found = 0;

	fs = get_fs();
	set_fs(get_ds());

	lock_kernel();
	while (count-- > 0) {
		peek_buf[0] = 0;

		result = -EIO;
		if (job->sk->dead) {
			PARANOIA("sock dead!\n");
			break;
		}

		result = _recvfrom(socket, (void *) peek_buf, 1,
				   MSG_PEEK | MSG_DONTWAIT);
		if (result < 0)
			break;
		if (peek_buf[0] != 0x85)
			break;

		/* got SESSION KEEP ALIVE */
		result = _recvfrom(socket, (void *) peek_buf, 4,
				   MSG_DONTWAIT);

		DEBUG1("got SESSION KEEPALIVE\n");

		if (result < 0)
			break;
		found = 1;
	}
	unlock_kernel();
	set_fs(fs);

	DEBUG1("found=%d, count=%d, result=%d\n", found, count, result);
	if (found)
		found_data(job->sk);
	smb_kfree(ptr);
}

static void
smb_data_ready(struct sock *sk, int len)
{
	struct data_callback* job;
	job = smb_kmalloc(sizeof(struct data_callback),GFP_ATOMIC);
	if(job == 0) {
		printk("smb_data_ready: lost SESSION KEEPALIVE due to OOM.\n");
		found_data(sk);
		return;
	}
	INIT_LIST_HEAD(&job->cb.list);
	job->cb.sync = 0;
	job->cb.routine = smb_data_callback;
	job->cb.data = job;
	job->sk = sk;
	schedule_task(&job->cb);
}

int
smb_valid_socket(struct inode * inode)
{
	return (inode && S_ISSOCK(inode->i_mode) && 
		inode->u.socket_i.type == SOCK_STREAM);
}

static struct socket *
server_sock(struct smb_sb_info *server)
{
	struct file *file;

	if (server && (file = server->sock_file))
	{
#ifdef SMBFS_PARANOIA
		if (!smb_valid_socket(file->f_dentry->d_inode))
			PARANOIA("bad socket!\n");
#endif
		return &file->f_dentry->d_inode->u.socket_i;
	}
	return NULL;
}

int
smb_catch_keepalive(struct smb_sb_info *server)
{
	struct socket *socket;
	struct sock *sk;
	void *data_ready;
	int error;

	error = -EINVAL;
	socket = server_sock(server);
	if (!socket)
	{
		printk(KERN_DEBUG "smb_catch_keepalive: did not get valid server!\n");
		server->data_ready = NULL;
		goto out;
	}

	sk = socket->sk;
	if (sk == NULL)
	{
		DEBUG1("sk == NULL");
		server->data_ready = NULL;
		goto out;
	}
	DEBUG1("sk->d_r = %x, server->d_r = %x\n",
		 (unsigned int) (sk->data_ready),
		 (unsigned int) (server->data_ready));

	/*
	 * Install the callback atomically to avoid races ...
	 */
	data_ready = xchg(&sk->data_ready, smb_data_ready);
	if (data_ready != smb_data_ready) {
		server->data_ready = data_ready;
		error = 0;
	} else
		printk(KERN_ERR "smb_catch_keepalive: already done\n");
out:
	return error;
}

int
smb_dont_catch_keepalive(struct smb_sb_info *server)
{
	struct socket *socket;
	struct sock *sk;
	void * data_ready;
	int error;

	error = -EINVAL;
	socket = server_sock(server);
	if (!socket)
	{
		printk(KERN_DEBUG "smb_dont_catch_keepalive: did not get valid server!\n");
		goto out;
	}

	sk = socket->sk;
	if (sk == NULL)
	{
		DEBUG1("sk == NULL");
		goto out;
	}

	/* Is this really an error?? */
	if (server->data_ready == NULL)
	{
		printk(KERN_DEBUG "smb_dont_catch_keepalive: "
		       "server->data_ready == NULL\n");
		goto out;
	}
	DEBUG1("smb_dont_catch_keepalive: sk->d_r = %x, server->d_r = %x\n",
	       (unsigned int) (sk->data_ready),
	       (unsigned int) (server->data_ready));

	/*
	 * Restore the original callback atomically to avoid races ...
	 */
	data_ready = xchg(&sk->data_ready, server->data_ready);
	server->data_ready = NULL;
	if (data_ready != smb_data_ready)
	{
		printk(KERN_ERR "smb_dont_catch_keepalive: "
		       "sk->data_ready != smb_data_ready\n");
	}
	error = 0;
out:
	return error;
}

/*
 * Called with the server locked.
 */
void
smb_close_socket(struct smb_sb_info *server)
{
	struct file * file = server->sock_file;

	if (file)
	{
		VERBOSE("closing socket %p\n", server_sock(server));
#ifdef SMBFS_PARANOIA
		if (server_sock(server)->sk->data_ready == smb_data_ready)
			PARANOIA("still catching keepalives!\n");
#endif
		server->sock_file = NULL;
		fput(file);
	}
}

static int
smb_send_raw(struct socket *socket, unsigned char *source, int length)
{
	int result;
	int already_sent = 0;

	while (already_sent < length)
	{
		result = _send(socket,
			       (void *) (source + already_sent),
			       length - already_sent);

		if (result == 0)
		{
			return -EIO;
		}
		if (result < 0)
		{
			DEBUG1("smb_send_raw: sendto error = %d\n", -result);
			return result;
		}
		already_sent += result;
	}
	return already_sent;
}

static int
smb_receive_raw(struct socket *socket, unsigned char *target, int length)
{
	int result;
	int already_read = 0;

	while (already_read < length)
	{
		result = _recvfrom(socket,
				   (void *) (target + already_read),
				   length - already_read, 0);

		if (result == 0)
		{
			return -EIO;
		}
		if (result < 0)
		{
			DEBUG1("recvfrom error = %d\n", -result);
			return result;
		}
		already_read += result;
	}
	return already_read;
}

static int
smb_get_length(struct socket *socket, unsigned char *header)
{
	int result;
	unsigned char peek_buf[4];
	mm_segment_t fs;

      re_recv:
	fs = get_fs();
	set_fs(get_ds());
	result = smb_receive_raw(socket, peek_buf, 4);
	set_fs(fs);

	if (result < 0)
	{
		PARANOIA("recv error = %d\n", -result);
		return result;
	}
	switch (peek_buf[0])
	{
	case 0x00:
	case 0x82:
		break;

	case 0x85:
		DEBUG1("Got SESSION KEEP ALIVE\n");
		goto re_recv;

	default:
		PARANOIA("Invalid NBT packet, code=%x\n", peek_buf[0]);
		return -EIO;
	}

	if (header != NULL)
	{
		memcpy(header, peek_buf, 4);
	}
	/* The length in the RFC NB header is the raw data length */
	return smb_len(peek_buf);
}

/*
 * Since we allocate memory in increments of PAGE_SIZE,
 * round up the packet length to the next multiple.
 */
int
smb_round_length(int len)
{
	return (len + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
}
 
/*
 * smb_receive
 * fs points to the correct segment
 */
static int
smb_receive(struct smb_sb_info *server)
{
	struct socket *socket = server_sock(server);
	unsigned char * packet = server->packet;
	int len, result;
	unsigned char peek_buf[4];

	result = smb_get_length(socket, peek_buf);
	if (result < 0)
		goto out;
	len = result;
	/*
	 * Some servers do not respect our max_xmit and send
	 * larger packets.  Try to allocate a new packet,
	 * but don't free the old one unless we succeed.
	 */
	if (len + 4 > server->packet_size)
	{
		int new_len = smb_round_length(len + 4);

		result = -ENOMEM;
		packet = smb_vmalloc(new_len);
		if (packet == NULL)
			goto out;
		smb_vfree(server->packet);
		server->packet = packet;
		server->packet_size = new_len;
	}