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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 | /* * 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@scyld.com> * * 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 = (16 * 1024) + 20 + 20 + 12; 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->features = NETIF_F_SG|NETIF_F_FRAGLIST|NETIF_F_NO_CSUM|NETIF_F_HIGHDMA; 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; /* * Fill in the generic fields of the device structure. */ return(0); }; |