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Linux/net/ax25/ax25_ip.c

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  1 /*
  2  * This program is free software; you can redistribute it and/or modify
  3  * it under the terms of the GNU General Public License as published by
  4  * the Free Software Foundation; either version 2 of the License, or
  5  * (at your option) any later version.
  6  *
  7  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
  8  */
  9 #include <linux/errno.h>
 10 #include <linux/types.h>
 11 #include <linux/socket.h>
 12 #include <linux/in.h>
 13 #include <linux/kernel.h>
 14 #include <linux/module.h>
 15 #include <linux/timer.h>
 16 #include <linux/string.h>
 17 #include <linux/sockios.h>
 18 #include <linux/net.h>
 19 #include <linux/slab.h>
 20 #include <net/ax25.h>
 21 #include <linux/inet.h>
 22 #include <linux/netdevice.h>
 23 #include <linux/if_arp.h>
 24 #include <linux/skbuff.h>
 25 #include <net/sock.h>
 26 #include <asm/uaccess.h>
 27 #include <linux/fcntl.h>
 28 #include <linux/termios.h>      /* For TIOCINQ/OUTQ */
 29 #include <linux/mm.h>
 30 #include <linux/interrupt.h>
 31 #include <linux/notifier.h>
 32 #include <linux/proc_fs.h>
 33 #include <linux/stat.h>
 34 #include <linux/netfilter.h>
 35 #include <linux/sysctl.h>
 36 #include <net/ip.h>
 37 #include <net/arp.h>
 38 
 39 /*
 40  *      IP over AX.25 encapsulation.
 41  */
 42 
 43 /*
 44  *      Shove an AX.25 UI header on an IP packet and handle ARP
 45  */
 46 
 47 #ifdef CONFIG_INET
 48 
 49 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
 50                      unsigned short type, const void *daddr,
 51                      const void *saddr, unsigned int len)
 52 {
 53         unsigned char *buff;
 54 
 55         /* they sometimes come back to us... */
 56         if (type == ETH_P_AX25)
 57                 return 0;
 58 
 59         /* header is an AX.25 UI frame from us to them */
 60         buff = skb_push(skb, AX25_HEADER_LEN);
 61         *buff++ = 0x00; /* KISS DATA */
 62 
 63         if (daddr != NULL)
 64                 memcpy(buff, daddr, dev->addr_len);     /* Address specified */
 65 
 66         buff[6] &= ~AX25_CBIT;
 67         buff[6] &= ~AX25_EBIT;
 68         buff[6] |= AX25_SSSID_SPARE;
 69         buff    += AX25_ADDR_LEN;
 70 
 71         if (saddr != NULL)
 72                 memcpy(buff, saddr, dev->addr_len);
 73         else
 74                 memcpy(buff, dev->dev_addr, dev->addr_len);
 75 
 76         buff[6] &= ~AX25_CBIT;
 77         buff[6] |= AX25_EBIT;
 78         buff[6] |= AX25_SSSID_SPARE;
 79         buff    += AX25_ADDR_LEN;
 80 
 81         *buff++  = AX25_UI;     /* UI */
 82 
 83         /* Append a suitable AX.25 PID */
 84         switch (type) {
 85         case ETH_P_IP:
 86                 *buff++ = AX25_P_IP;
 87                 break;
 88         case ETH_P_ARP:
 89                 *buff++ = AX25_P_ARP;
 90                 break;
 91         default:
 92                 printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
 93                 *buff++ = 0;
 94                 break;
 95         }
 96 
 97         if (daddr != NULL)
 98                 return AX25_HEADER_LEN;
 99 
100         return -AX25_HEADER_LEN;        /* Unfinished header */
101 }
102 
103 int ax25_rebuild_header(struct sk_buff *skb)
104 {
105         struct sk_buff *ourskb;
106         unsigned char *bp  = skb->data;
107         ax25_route *route;
108         struct net_device *dev = NULL;
109         ax25_address *src, *dst;
110         ax25_digi *digipeat = NULL;
111         ax25_dev *ax25_dev;
112         ax25_cb *ax25;
113         char ip_mode = ' ';
114 
115         dst = (ax25_address *)(bp + 1);
116         src = (ax25_address *)(bp + 8);
117 
118         if (arp_find(bp + 1, skb))
119                 return 1;
120 
121         route = ax25_get_route(dst, NULL);
122         if (route) {
123                 digipeat = route->digipeat;
124                 dev = route->dev;
125                 ip_mode = route->ip_mode;
126         }
127 
128         if (dev == NULL)
129                 dev = skb->dev;
130 
131         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
132                 goto put;
133         }
134 
135         if (bp[16] == AX25_P_IP) {
136                 if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
137                         /*
138                          *      We copy the buffer and release the original thereby
139                          *      keeping it straight
140                          *
141                          *      Note: we report 1 back so the caller will
142                          *      not feed the frame direct to the physical device
143                          *      We don't want that to happen. (It won't be upset
144                          *      as we have pulled the frame from the queue by
145                          *      freeing it).
146                          *
147                          *      NB: TCP modifies buffers that are still
148                          *      on a device queue, thus we use skb_copy()
149                          *      instead of using skb_clone() unless this
150                          *      gets fixed.
151                          */
152 
153                         ax25_address src_c;
154                         ax25_address dst_c;
155 
156                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
157                                 kfree_skb(skb);
158                                 goto put;
159                         }
160 
161                         if (skb->sk != NULL)
162                                 skb_set_owner_w(ourskb, skb->sk);
163 
164                         kfree_skb(skb);
165                         /* dl9sau: bugfix
166                          * after kfree_skb(), dst and src which were pointer
167                          * to bp which is part of skb->data would not be valid
168                          * anymore hope that after skb_pull(ourskb, ..) our
169                          * dsc_c and src_c will not become invalid
170                          */
171                         bp  = ourskb->data;
172                         dst_c = *(ax25_address *)(bp + 1);
173                         src_c = *(ax25_address *)(bp + 8);
174 
175                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
176                         skb_reset_network_header(ourskb);
177 
178                         ax25=ax25_send_frame(
179                             ourskb,
180                             ax25_dev->values[AX25_VALUES_PACLEN],
181                             &src_c,
182                             &dst_c, digipeat, dev);
183                         if (ax25) {
184                                 ax25_cb_put(ax25);
185                         }
186                         goto put;
187                 }
188         }
189 
190         bp[7]  &= ~AX25_CBIT;
191         bp[7]  &= ~AX25_EBIT;
192         bp[7]  |= AX25_SSSID_SPARE;
193 
194         bp[14] &= ~AX25_CBIT;
195         bp[14] |= AX25_EBIT;
196         bp[14] |= AX25_SSSID_SPARE;
197 
198         skb_pull(skb, AX25_KISS_HEADER_LEN);
199 
200         if (digipeat != NULL) {
201                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
202                         kfree_skb(skb);
203                         goto put;
204                 }
205 
206                 skb = ourskb;
207         }
208 
209         ax25_queue_xmit(skb, dev);
210 
211 put:
212         if (route)
213                 ax25_put_route(route);
214 
215         return 1;
216 }
217 
218 #else   /* INET */
219 
220 int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
221                      unsigned short type, const void *daddr,
222                      const void *saddr, unsigned int len)
223 {
224         return -AX25_HEADER_LEN;
225 }
226 
227 int ax25_rebuild_header(struct sk_buff *skb)
228 {
229         return 1;
230 }
231 
232 #endif
233 
234 const struct header_ops ax25_header_ops = {
235         .create = ax25_hard_header,
236         .rebuild = ax25_rebuild_header,
237 };
238 
239 EXPORT_SYMBOL(ax25_hard_header);
240 EXPORT_SYMBOL(ax25_rebuild_header);
241 EXPORT_SYMBOL(ax25_header_ops);
242 
243 

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