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/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Pseudo-driver for the loopback interface.
*
* Version: @(#)loopback.c 1.0.4b 08/16/93
*
* Authors: Ross Biro, <bir7@leland.Stanford.Edu>
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Donald Becker, <becker@cesdis.gsfc.nasa.gov>
*
* Alan Cox : Fixed oddments for NET3.014
* Alan Cox : Rejig for NET3.029 snap #3
* Alan Cox : Fixed NET3.029 bugs and sped up
* Larry McVoy : Tiny tweak to double performance
* Alan Cox : Backed out LMV's tweak - the linux mm
* can't take it...
* Michael Griffith: Don't bother computing the checksums
* on packets received on the loopback
* interface.
* Alexey Kuznetsov: Potential hang under some extreme
* cases removed.
*
* 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/kernel.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/in.h>
#include <linux/init.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/if_ether.h> /* For the statistics structure. */
#include <linux/if_arp.h> /* For ARPHRD_ETHER */
#define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
/*
* The higher levels take care of making this non-reentrant (it's
* called with bh's disabled).
*/
static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct net_device_stats *stats = (struct net_device_stats *)dev->priv;
/*
* Optimise so buffers with skb->free=1 are not copied but
* instead are lobbed from tx queue to rx queue
*/
if(atomic_read(&skb->users) != 1)
{
struct sk_buff *skb2=skb;
skb=skb_clone(skb, GFP_ATOMIC); /* Clone the buffer */
if(skb==NULL) {
kfree_skb(skb2);
return 0;
}
kfree_skb(skb2);
}
else
skb_orphan(skb);
skb->protocol=eth_type_trans(skb,dev);
skb->dev=dev;
#ifndef LOOPBACK_MUST_CHECKSUM
skb->ip_summed = CHECKSUM_UNNECESSARY;
#endif
dev->last_rx = jiffies;
stats->rx_bytes+=skb->len;
stats->tx_bytes+=skb->len;
stats->rx_packets++;
stats->tx_packets++;
netif_rx(skb);
return(0);
}
static struct net_device_stats *get_stats(struct net_device *dev)
{
return (struct net_device_stats *)dev->priv;
}
/* Initialize the rest of the LOOPBACK device. */
int __init loopback_init(struct net_device *dev)
{
dev->mtu = PAGE_SIZE - LOOPBACK_OVERHEAD;
dev->hard_start_xmit = loopback_xmit;
dev->hard_header = eth_header;
dev->hard_header_cache = eth_header_cache;
dev->header_cache_update= eth_header_cache_update;
dev->hard_header_len = ETH_HLEN; /* 14 */
dev->addr_len = ETH_ALEN; /* 6 */
dev->tx_queue_len = 0;
dev->type = ARPHRD_LOOPBACK; /* 0x0001 */
dev->rebuild_header = eth_rebuild_header;
dev->flags = IFF_LOOPBACK;
dev->priv = kmalloc(sizeof(struct net_device_stats), GFP_KERNEL);
if (dev->priv == NULL)
return -ENOMEM;
memset(dev->priv, 0, sizeof(struct net_device_stats));
dev->get_stats = get_stats;
if (num_physpages >= ((128*1024*1024)>>PAGE_SHIFT))
dev->mtu = 4096*4 - LOOPBACK_OVERHEAD;
/*
* Fill in the generic fields of the device structure.
*/
dev_init_buffers(dev);
return(0);
};
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