1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              Pseudo-driver for the loopback interface.
  7  *
  8  * Version:     @(#)loopback.c  1.0.4b  08/16/93
  9  *
 10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
 11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 12  *              Donald Becker, <becker@super.org>
 13  *
 14  *              This program is free software; you can redistribute it and/or
 15  *              modify it under the terms of the GNU General Public License
 16  *              as published by the Free Software Foundation; either version
 17  *              2 of the License, or (at your option) any later version.
 18  */
 19 #include <linux/config.h>
 20 #include <linux/kernel.h>
 21 #include <linux/sched.h>
 22 #include <linux/fs.h>
 23 #include <linux/types.h>
 24 #include <linux/string.h>
 25 #include <linux/socket.h>
 26 #include <linux/errno.h>
 27 #include <linux/fcntl.h>
 28 #include <linux/in.h>
 29 #include <linux/if_ether.h>     /* For the statistics structure. */
 30 
 31 #include <asm/system.h>
 32 #include <asm/segment.h>
 33 #include <asm/io.h>
 34 
 35 #include "inet.h"
 36 #include "dev.h"
 37 #include "eth.h"
 38 #include "ip.h"
 39 #include "protocol.h"
 40 #include "tcp.h"
 41 #include "skbuff.h"
 42 #include "sock.h"
 43 #include "arp.h"
 44 
 45 
 46 static int
 47 loopback_xmit(struct sk_buff *skb, struct device *dev)
 48 {
 49   struct enet_statistics *stats = (struct enet_statistics *)dev->priv;
 50   int done;
 51 
 52   DPRINTF((DBG_LOOPB, "loopback_xmit(dev=%X, skb=%X)\n", dev, skb));
 53   if (skb == NULL || dev == NULL) return(0);
 54 
 55   cli();
 56   if (dev->tbusy != 0) {
 57         sti();
 58         stats->tx_errors++;
 59         return(1);
 60   }
 61   dev->tbusy = 1;
 62   sti();
 63 
 64   done = dev_rint(skb->data, skb->len, 0, dev);
 65   if (skb->free) kfree_skb(skb, FREE_WRITE);
 66 
 67   while (done != 1) {
 68         done = dev_rint(NULL, 0, 0, dev);
 69   }
 70   stats->tx_packets++;
 71 
 72   dev->tbusy = 0;
 73 
 74 #if 1
 75         __asm__("cmpl $0,_intr_count\n\t"
 76                 "jne 1f\n\t"
 77                 "movl _bh_active,%%eax\n\t"
 78                 "testl _bh_mask,%%eax\n\t"
 79                 "je 1f\n\t"
 80                 "incl _intr_count\n\t"
 81                 "call _do_bottom_half\n\t"
 82                 "decl _intr_count\n"
 83                 "1:"
 84                 :
 85                 :
 86                 : "ax", "dx", "cx");
 87 #endif
 88 
 89   return(0);
 90 }
 91 
 92 static struct enet_statistics *
 93 get_stats(struct device *dev)
 94 {
 95     return (struct enet_statistics *)dev->priv;
 96 }
 97 
 98 /* Initialize the rest of the LOOPBACK device. */
 99 int
100 loopback_init(struct device *dev)
101 {
102   dev->mtu              = 2000;                 /* MTU                  */
103   dev->tbusy            = 0;
104   dev->hard_start_xmit  = loopback_xmit;
105   dev->open             = NULL;
106 #if 1
107   dev->hard_header      = eth_header;
108   dev->add_arp          = NULL;
109   dev->hard_header_len  = ETH_HLEN;             /* 14                   */
110   dev->addr_len         = ETH_ALEN;             /* 6                    */
111   dev->type             = ARPHRD_ETHER;         /* 0x0001               */
112   dev->type_trans       = eth_type_trans;
113   dev->rebuild_header   = eth_rebuild_header;
114 #else
115   dev->hard_header_length = 0;
116   dev->add_arp          = NULL;
117   dev->addr_len         = 0;
118   dev->type             = 0;                    /* loopback_type (0)    */
119   dev->hard_header      = NULL;
120   dev->type_trans       = NULL;
121   dev->rebuild_header   = NULL;
122 #endif
123   dev->queue_xmit       = dev_queue_xmit;
124 
125   /* New-style flags. */
126   dev->flags            = IFF_LOOPBACK;
127   dev->family           = AF_INET;
128   dev->pa_addr          = in_aton("127.0.0.1");
129   dev->pa_brdaddr       = in_aton("127.255.255.255");
130   dev->pa_mask          = in_aton("255.0.0.0");
131   dev->pa_alen          = sizeof(unsigned long);
132   dev->priv = kmalloc(sizeof(struct enet_statistics), GFP_KERNEL);
133   memset(dev->priv, 0, sizeof(struct enet_statistics));
134   dev->get_stats = get_stats;
135   
136   return(0);
137 };
138