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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [uIP_Demo_Rowley_ARM7/] [uip/] [uip_arp.c] - Blame information for rev 609

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Line No. Rev Author Line
1 583 jeremybenn
/**
2
 * \addtogroup uip
3
 * @{
4
 */
5
 
6
/**
7
 * \defgroup uiparp uIP Address Resolution Protocol
8
 * @{
9
 *
10
 * The Address Resolution Protocol ARP is used for mapping between IP
11
 * addresses and link level addresses such as the Ethernet MAC
12
 * addresses. ARP uses broadcast queries to ask for the link level
13
 * address of a known IP address and the host which is configured with
14
 * the IP address for which the query was meant, will respond with its
15
 * link level address.
16
 *
17
 * \note This ARP implementation only supports Ethernet.
18
 */
19
 
20
/**
21
 * \file
22
 * Implementation of the ARP Address Resolution Protocol.
23
 * \author Adam Dunkels <adam@dunkels.com>
24
 *
25
 */
26
 
27
/*
28
 * Copyright (c) 2001-2003, Adam Dunkels.
29
 * All rights reserved.
30
 *
31
 * Redistribution and use in source and binary forms, with or without
32
 * modification, are permitted provided that the following conditions
33
 * are met:
34
 * 1. Redistributions of source code must retain the above copyright
35
 *    notice, this list of conditions and the following disclaimer.
36
 * 2. Redistributions in binary form must reproduce the above copyright
37
 *    notice, this list of conditions and the following disclaimer in the
38
 *    documentation and/or other materials provided with the distribution.
39
 * 3. The name of the author may not be used to endorse or promote
40
 *    products derived from this software without specific prior
41
 *    written permission.
42
 *
43
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
44
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
45
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
46
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
47
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
48
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
49
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
50
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
51
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
52
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
53
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
54
 *
55
 * This file is part of the uIP TCP/IP stack.
56
 *
57
 * $Id: uip_arp.c 2 2011-07-17 20:13:17Z filepang@gmail.com $
58
 *
59
 */
60
 
61
 
62
#include "uip_arp.h"
63
 
64
#include <string.h>
65
 
66
struct arp_hdr {
67
  struct uip_eth_hdr ethhdr;
68
  u16_t hwtype;
69
  u16_t protocol;
70
  u8_t hwlen;
71
  u8_t protolen;
72
  u16_t opcode;
73
  struct uip_eth_addr shwaddr;
74
  u16_t sipaddr[2];
75
  struct uip_eth_addr dhwaddr;
76
  u16_t dipaddr[2];
77
};
78
 
79
struct ethip_hdr {
80
  struct uip_eth_hdr ethhdr;
81
  /* IP header. */
82
  u8_t vhl,
83
    tos,
84
    len[2],
85
    ipid[2],
86
    ipoffset[2],
87
    ttl,
88
    proto;
89
  u16_t ipchksum;
90
  u16_t srcipaddr[2],
91
    destipaddr[2];
92
};
93
 
94
#define ARP_REQUEST 1
95
#define ARP_REPLY   2
96
 
97
#define ARP_HWTYPE_ETH 1
98
 
99
struct arp_entry {
100
  u16_t ipaddr[2];
101
  struct uip_eth_addr ethaddr;
102
  u8_t time;
103
};
104
 
105
struct uip_eth_addr uip_ethaddr = {{UIP_ETHADDR0,
106
                                    UIP_ETHADDR1,
107
                                    UIP_ETHADDR2,
108
                                    UIP_ETHADDR3,
109
                                    UIP_ETHADDR4,
110
                                    UIP_ETHADDR5}};
111
 
112
static struct arp_entry arp_table[UIP_ARPTAB_SIZE];
113
static u16_t ipaddr[2];
114
static u8_t i, c;
115
 
116
static u8_t arptime;
117
static u8_t tmpage;
118
 
119
#define BUF   ((struct arp_hdr *)&uip_buf[0])
120
#define IPBUF ((struct ethip_hdr *)&uip_buf[0])
121
/*-----------------------------------------------------------------------------------*/
122
/**
123
 * Initialize the ARP module.
124
 *
125
 */
126
/*-----------------------------------------------------------------------------------*/
127
void
128
uip_arp_init(void)
129
{
130
  for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
131
    memset(arp_table[i].ipaddr, 0, 4);
132
  }
133
}
134
/*-----------------------------------------------------------------------------------*/
135
/**
136
 * Periodic ARP processing function.
137
 *
138
 * This function performs periodic timer processing in the ARP module
139
 * and should be called at regular intervals. The recommended interval
140
 * is 10 seconds between the calls.
141
 *
142
 */
143
/*-----------------------------------------------------------------------------------*/
144
void
145
uip_arp_timer(void)
146
{
147
  struct arp_entry *tabptr;
148
 
149
  ++arptime;
150
  for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
151
    tabptr = &arp_table[i];
152
    if((tabptr->ipaddr[0] | tabptr->ipaddr[1]) != 0 &&
153
       arptime - tabptr->time >= UIP_ARP_MAXAGE) {
154
      memset(tabptr->ipaddr, 0, 4);
155
    }
156
  }
157
 
158
}
159
/*-----------------------------------------------------------------------------------*/
160
static void
161
uip_arp_update(u16_t *ipaddr, struct uip_eth_addr *ethaddr)
162
{
163
  register struct arp_entry *tabptr;
164
  /* Walk through the ARP mapping table and try to find an entry to
165
     update. If none is found, the IP -> MAC address mapping is
166
     inserted in the ARP table. */
167
  for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
168
 
169
    tabptr = &arp_table[i];
170
    /* Only check those entries that are actually in use. */
171
    if(tabptr->ipaddr[0] != 0 &&
172
       tabptr->ipaddr[1] != 0) {
173
 
174
      /* Check if the source IP address of the incoming packet matches
175
         the IP address in this ARP table entry. */
176
      if(ipaddr[0] == tabptr->ipaddr[0] &&
177
         ipaddr[1] == tabptr->ipaddr[1]) {
178
 
179
        /* An old entry found, update this and return. */
180
        memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6);
181
        tabptr->time = arptime;
182
 
183
        return;
184
      }
185
    }
186
  }
187
 
188
  /* If we get here, no existing ARP table entry was found, so we
189
     create one. */
190
 
191
  /* First, we try to find an unused entry in the ARP table. */
192
  for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
193
    tabptr = &arp_table[i];
194
    if(tabptr->ipaddr[0] == 0 &&
195
       tabptr->ipaddr[1] == 0) {
196
      break;
197
    }
198
  }
199
 
200
  /* If no unused entry is found, we try to find the oldest entry and
201
     throw it away. */
202
  if(i == UIP_ARPTAB_SIZE) {
203
    tmpage = 0;
204
    c = 0;
205
    for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
206
      tabptr = &arp_table[i];
207
      if(arptime - tabptr->time > tmpage) {
208
        tmpage = arptime - tabptr->time;
209
        c = i;
210
      }
211
    }
212
    i = c;
213
  }
214
 
215
  /* Now, i is the ARP table entry which we will fill with the new
216
     information. */
217
  memcpy(tabptr->ipaddr, ipaddr, 4);
218
  memcpy(tabptr->ethaddr.addr, ethaddr->addr, 6);
219
  tabptr->time = arptime;
220
}
221
/*-----------------------------------------------------------------------------------*/
222
/**
223
 * ARP processing for incoming IP packets
224
 *
225
 * This function should be called by the device driver when an IP
226
 * packet has been received. The function will check if the address is
227
 * in the ARP cache, and if so the ARP cache entry will be
228
 * refreshed. If no ARP cache entry was found, a new one is created.
229
 *
230
 * This function expects an IP packet with a prepended Ethernet header
231
 * in the uip_buf[] buffer, and the length of the packet in the global
232
 * variable uip_len.
233
 */
234
/*-----------------------------------------------------------------------------------*/
235
void
236
uip_arp_ipin(void)
237
{
238
  uip_len -= sizeof(struct uip_eth_hdr);
239
 
240
  /* Only insert/update an entry if the source IP address of the
241
     incoming IP packet comes from a host on the local network. */
242
  if((IPBUF->srcipaddr[0] & uip_arp_netmask[0]) !=
243
     (uip_hostaddr[0] & uip_arp_netmask[0])) {
244
    return;
245
  }
246
  if((IPBUF->srcipaddr[1] & uip_arp_netmask[1]) !=
247
     (uip_hostaddr[1] & uip_arp_netmask[1])) {
248
    return;
249
  }
250
  uip_arp_update(IPBUF->srcipaddr, &(IPBUF->ethhdr.src));
251
 
252
  return;
253
}
254
/*-----------------------------------------------------------------------------------*/
255
/**
256
 * ARP processing for incoming ARP packets.
257
 *
258
 * This function should be called by the device driver when an ARP
259
 * packet has been received. The function will act differently
260
 * depending on the ARP packet type: if it is a reply for a request
261
 * that we previously sent out, the ARP cache will be filled in with
262
 * the values from the ARP reply. If the incoming ARP packet is an ARP
263
 * request for our IP address, an ARP reply packet is created and put
264
 * into the uip_buf[] buffer.
265
 *
266
 * When the function returns, the value of the global variable uip_len
267
 * indicates whether the device driver should send out a packet or
268
 * not. If uip_len is zero, no packet should be sent. If uip_len is
269
 * non-zero, it contains the length of the outbound packet that is
270
 * present in the uip_buf[] buffer.
271
 *
272
 * This function expects an ARP packet with a prepended Ethernet
273
 * header in the uip_buf[] buffer, and the length of the packet in the
274
 * global variable uip_len.
275
 */
276
/*-----------------------------------------------------------------------------------*/
277
typedef struct arp_hdr aht;
278
 
279
void
280
uip_arp_arpin(void)
281
{
282
  int ul;
283
 
284
  if(uip_len < sizeof(struct arp_hdr)) {
285
    uip_len = 0;
286
    return;
287
  }
288
 
289
  uip_len = 0;
290
 
291
  switch(BUF->opcode) {
292
  case HTONS(ARP_REQUEST):
293
    /* ARP request. If it asked for our address, we send out a
294
       reply. */
295
    if(BUF->dipaddr[0] == uip_hostaddr[0] &&
296
       BUF->dipaddr[1] == uip_hostaddr[1]) {
297
      /* The reply opcode is 2. */
298
      BUF->opcode = HTONS(2);
299
 
300
      memcpy(BUF->dhwaddr.addr, BUF->shwaddr.addr, 6);
301
      memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6);
302
      memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
303
      memcpy(BUF->ethhdr.dest.addr, BUF->dhwaddr.addr, 6);
304
 
305
      BUF->dipaddr[0] = BUF->sipaddr[0];
306
      BUF->dipaddr[1] = BUF->sipaddr[1];
307
      BUF->sipaddr[0] = uip_hostaddr[0];
308
      BUF->sipaddr[1] = uip_hostaddr[1];
309
 
310
      ul = BUF->hwlen;
311
      BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP);
312
      uip_len = sizeof(struct arp_hdr);
313
    }
314
    break;
315
  case HTONS(ARP_REPLY):
316
    /* ARP reply. We insert or update the ARP table if it was meant
317
       for us. */
318
    if(BUF->dipaddr[0] == uip_hostaddr[0] &&
319
       BUF->dipaddr[1] == uip_hostaddr[1]) {
320
 
321
      uip_arp_update(BUF->sipaddr, &BUF->shwaddr);
322
    }
323
    break;
324
  }
325
 
326
  return;
327
}
328
/*-----------------------------------------------------------------------------------*/
329
/**
330
 * Prepend Ethernet header to an outbound IP packet and see if we need
331
 * to send out an ARP request.
332
 *
333
 * This function should be called before sending out an IP packet. The
334
 * function checks the destination IP address of the IP packet to see
335
 * what Ethernet MAC address that should be used as a destination MAC
336
 * address on the Ethernet.
337
 *
338
 * If the destination IP address is in the local network (determined
339
 * by logical ANDing of netmask and our IP address), the function
340
 * checks the ARP cache to see if an entry for the destination IP
341
 * address is found. If so, an Ethernet header is prepended and the
342
 * function returns. If no ARP cache entry is found for the
343
 * destination IP address, the packet in the uip_buf[] is replaced by
344
 * an ARP request packet for the IP address. The IP packet is dropped
345
 * and it is assumed that they higher level protocols (e.g., TCP)
346
 * eventually will retransmit the dropped packet.
347
 *
348
 * If the destination IP address is not on the local network, the IP
349
 * address of the default router is used instead.
350
 *
351
 * When the function returns, a packet is present in the uip_buf[]
352
 * buffer, and the length of the packet is in the global variable
353
 * uip_len.
354
 */
355
/*-----------------------------------------------------------------------------------*/
356
void
357
uip_arp_out(void)
358
{
359
  struct arp_entry *tabptr;
360
  /* Find the destination IP address in the ARP table and construct
361
     the Ethernet header. If the destination IP addres isn't on the
362
     local network, we use the default router's IP address instead.
363
 
364
     If not ARP table entry is found, we overwrite the original IP
365
     packet with an ARP request for the IP address. */
366
 
367
  /* Check if the destination address is on the local network. */
368
  if((IPBUF->destipaddr[0] & uip_arp_netmask[0]) !=
369
     (uip_hostaddr[0] & uip_arp_netmask[0]) ||
370
     (IPBUF->destipaddr[1] & uip_arp_netmask[1]) !=
371
     (uip_hostaddr[1] & uip_arp_netmask[1])) {
372
    /* Destination address was not on the local network, so we need to
373
       use the default router's IP address instead of the destination
374
       address when determining the MAC address. */
375
    ipaddr[0] = uip_arp_draddr[0];
376
    ipaddr[1] = uip_arp_draddr[1];
377
  } else {
378
    /* Else, we use the destination IP address. */
379
    ipaddr[0] = IPBUF->destipaddr[0];
380
    ipaddr[1] = IPBUF->destipaddr[1];
381
  }
382
 
383
  for(i = 0; i < UIP_ARPTAB_SIZE; ++i) {
384
    tabptr = &arp_table[i];
385
    if(ipaddr[0] == tabptr->ipaddr[0] &&
386
       ipaddr[1] == tabptr->ipaddr[1])
387
      break;
388
  }
389
 
390
  if(i == UIP_ARPTAB_SIZE) {
391
    /* The destination address was not in our ARP table, so we
392
       overwrite the IP packet with an ARP request. */
393
 
394
    memset(BUF->ethhdr.dest.addr, 0xff, 6);
395
    memset(BUF->dhwaddr.addr, 0x00, 6);
396
    memcpy(BUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
397
    memcpy(BUF->shwaddr.addr, uip_ethaddr.addr, 6);
398
 
399
    BUF->dipaddr[0] = ipaddr[0];
400
    BUF->dipaddr[1] = ipaddr[1];
401
    BUF->sipaddr[0] = uip_hostaddr[0];
402
    BUF->sipaddr[1] = uip_hostaddr[1];
403
    BUF->opcode = HTONS(ARP_REQUEST); /* ARP request. */
404
    BUF->hwtype = HTONS(ARP_HWTYPE_ETH);
405
    BUF->protocol = HTONS(UIP_ETHTYPE_IP);
406
    BUF->hwlen = 6;
407
    BUF->protolen = 4;
408
    BUF->ethhdr.type = HTONS(UIP_ETHTYPE_ARP);
409
 
410
    uip_appdata = &uip_buf[40 + UIP_LLH_LEN];
411
 
412
    uip_len = sizeof(struct arp_hdr);
413
    return;
414
  }
415
 
416
  /* Build an ethernet header. */
417
  memcpy(IPBUF->ethhdr.dest.addr, tabptr->ethaddr.addr, 6);
418
  memcpy(IPBUF->ethhdr.src.addr, uip_ethaddr.addr, 6);
419
 
420
  IPBUF->ethhdr.type = HTONS(UIP_ETHTYPE_IP);
421
 
422
  uip_len += sizeof(struct uip_eth_hdr);
423
}
424
/*-----------------------------------------------------------------------------------*/
425
 
426
/** @} */
427
/** @} */

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