1 /*
2  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without modification,
6  * are permitted provided that the following conditions are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright notice,
9  *    this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright notice,
11  *    this list of conditions and the following disclaimer in the documentation
12  *    and/or other materials provided with the distribution.
13  * 3. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
19  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
21  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
24  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
25  * OF SUCH DAMAGE.
26  *
27  * This file is part of the lwIP TCP/IP stack.
28  *
29  * Author: Adam Dunkels <adam@sics.se>
30  *
31  */
32 
33 
34 
35 /* ip.c
36  *
37  * This is the code for the IP layer for IPv6.
38  *
39  */
40 
41 
42 #include "lwip/opt.h"
43 
44 #include "lwip/def.h"
45 #include "lwip/mem.h"
46 #include "lwip/ip.h"
47 #include "lwip/inet.h"
48 #include "lwip/netif.h"
49 #include "lwip/icmp.h"
50 #include "lwip/udp.h"
51 #include "lwip/tcp_impl.h"
52 
53 #include "lwip/stats.h"
54 
55 #include "arch/perf.h"
56 
57 /* ip_init:
58  *
59  * Initializes the IP layer.
60  */
61 
62 void
ip_init(void)63 ip_init(void)
64 {
65 }
66 
67 /* ip_route:
68  *
69  * Finds the appropriate network interface for a given IP address. It searches the
70  * list of network interfaces linearly. A match is found if the masked IP address of
71  * the network interface equals the masked IP address given to the function.
72  */
73 
74 struct netif *
ip_route(struct ip_addr * dest)75 ip_route(struct ip_addr *dest)
76 {
77   struct netif *netif;
78 
79   for(netif = netif_list; netif != NULL; netif = netif->next) {
80     if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {
81       return netif;
82     }
83   }
84 
85   return netif_default;
86 }
87 
88 /* ip_forward:
89  *
90  * Forwards an IP packet. It finds an appropriate route for the packet, decrements
91  * the TTL value of the packet, adjusts the checksum and outputs the packet on the
92  * appropriate interface.
93  */
94 
95 static void
ip_forward(struct pbuf * p,struct ip_hdr * iphdr)96 ip_forward(struct pbuf *p, struct ip_hdr *iphdr)
97 {
98   struct netif *netif;
99 
100   PERF_START;
101 
102   if ((netif = ip_route((struct ip_addr *)&(iphdr->dest))) == NULL) {
103 
104     LWIP_DEBUGF(IP_DEBUG, ("ip_input: no forwarding route found for "));
105 #if IP_DEBUG
106     ip_addr_debug_print(IP_DEBUG, ((struct ip_addr *)&(iphdr->dest)));
107 #endif /* IP_DEBUG */
108     LWIP_DEBUGF(IP_DEBUG, ("\n"));
109     pbuf_free(p);
110     return;
111   }
112   /* Decrement TTL and send ICMP if ttl == 0. */
113   if (--iphdr->hoplim == 0) {
114 #if LWIP_ICMP
115     /* Don't send ICMP messages in response to ICMP messages */
116     if (iphdr->nexthdr != IP_PROTO_ICMP) {
117       icmp_time_exceeded(p, ICMP_TE_TTL);
118     }
119 #endif /* LWIP_ICMP */
120     pbuf_free(p);
121     return;
122   }
123 
124   /* Incremental update of the IP checksum. */
125   /*  if (iphdr->chksum >= htons(0xffff - 0x100)) {
126     iphdr->chksum += htons(0x100) + 1;
127   } else {
128     iphdr->chksum += htons(0x100);
129     }*/
130 
131 
132   LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to "));
133 #if IP_DEBUG
134   ip_addr_debug_print(IP_DEBUG, ((struct ip_addr *)&(iphdr->dest)));
135 #endif /* IP_DEBUG */
136   LWIP_DEBUGF(IP_DEBUG, ("\n"));
137 
138   IP_STATS_INC(ip.fw);
139   IP_STATS_INC(ip.xmit);
140 
141   PERF_STOP("ip_forward");
142 
143   netif->output(netif, p, (struct ip_addr *)&(iphdr->dest));
144 }
145 
146 /* ip_input:
147  *
148  * This function is called by the network interface device driver when an IP packet is
149  * received. The function does the basic checks of the IP header such as packet size
150  * being at least larger than the header size etc. If the packet was not destined for
151  * us, the packet is forwarded (using ip_forward). The IP checksum is always checked.
152  *
153  * Finally, the packet is sent to the upper layer protocol input function.
154  */
155 
156 void
ip_input(struct pbuf * p,struct netif * inp)157 ip_input(struct pbuf *p, struct netif *inp) {
158   struct ip_hdr *iphdr;
159   struct netif *netif;
160 
161 
162   PERF_START;
163 
164 #if IP_DEBUG
165   ip_debug_print(p);
166 #endif /* IP_DEBUG */
167 
168 
169   IP_STATS_INC(ip.recv);
170 
171   /* identify the IP header */
172   iphdr = p->payload;
173 
174 
175   if (iphdr->v != 6) {
176     LWIP_DEBUGF(IP_DEBUG, ("IP packet dropped due to bad version number\n"));
177 #if IP_DEBUG
178     ip_debug_print(p);
179 #endif /* IP_DEBUG */
180     pbuf_free(p);
181     IP_STATS_INC(ip.err);
182     IP_STATS_INC(ip.drop);
183     return;
184   }
185 
186   /* is this packet for us? */
187   for(netif = netif_list; netif != NULL; netif = netif->next) {
188 #if IP_DEBUG
189     LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest "));
190     ip_addr_debug_print(IP_DEBUG, ((struct ip_addr *)&(iphdr->dest)));
191     LWIP_DEBUGF(IP_DEBUG, ("netif->ip_addr "));
192     ip_addr_debug_print(IP_DEBUG, ((struct ip_addr *)&(iphdr->dest)));
193     LWIP_DEBUGF(IP_DEBUG, ("\n"));
194 #endif /* IP_DEBUG */
195     if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr))) {
196       break;
197     }
198   }
199 
200 
201   if (netif == NULL) {
202     /* packet not for us, route or discard */
203 #if IP_FORWARD
204     ip_forward(p, iphdr);
205 #endif
206     pbuf_free(p);
207     return;
208   }
209 
210   pbuf_realloc(p, IP_HLEN + ntohs(iphdr->len));
211 
212   /* send to upper layers */
213 #if IP_DEBUG
214   /*  LWIP_DEBUGF("ip_input: \n");
215   ip_debug_print(p);
216   LWIP_DEBUGF("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len);*/
217 #endif /* IP_DEBUG */
218 
219   if(pbuf_header(p, -IP_HLEN)) {
220     LWIP_ASSERT("Can't move over header in packet", 0);
221     return;
222   }
223 
224   switch (iphdr->nexthdr) {
225   case IP_PROTO_UDP:
226     udp_input(p, inp);
227     break;
228   case IP_PROTO_TCP:
229     tcp_input(p, inp);
230     break;
231 #if LWIP_ICMP
232   case IP_PROTO_ICMP:
233     icmp_input(p, inp);
234     break;
235 #endif /* LWIP_ICMP */
236   default:
237 #if LWIP_ICMP
238     /* send ICMP destination protocol unreachable */
239     icmp_dest_unreach(p, ICMP_DUR_PROTO);
240 #endif /* LWIP_ICMP */
241     pbuf_free(p);
242     LWIP_DEBUGF(IP_DEBUG, ("Unsupported transport protocol %"U16_F"\n",
243           iphdr->nexthdr));
244 
245     IP_STATS_INC(ip.proterr);
246     IP_STATS_INC(ip.drop);
247   }
248   PERF_STOP("ip_input");
249 }
250 
251 
252 /* ip_output_if:
253  *
254  * Sends an IP packet on a network interface. This function constructs the IP header
255  * and calculates the IP header checksum. If the source IP address is NULL,
256  * the IP address of the outgoing network interface is filled in as source address.
257  */
258 
259 err_t
ip_output_if(struct pbuf * p,struct ip_addr * src,struct ip_addr * dest,u8_t ttl,u8_t proto,struct netif * netif)260 ip_output_if (struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
261        u8_t ttl,
262        u8_t proto, struct netif *netif)
263 {
264   struct ip_hdr *iphdr;
265 
266   PERF_START;
267 
268   LWIP_DEBUGF(IP_DEBUG, ("len %"U16_F" tot_len %"U16_F"\n", p->len, p->tot_len));
269   if (pbuf_header(p, IP_HLEN)) {
270     LWIP_DEBUGF(IP_DEBUG, ("ip_output: not enough room for IP header in pbuf\n"));
271     IP_STATS_INC(ip.err);
272 
273     return ERR_BUF;
274   }
275   LWIP_DEBUGF(IP_DEBUG, ("len %"U16_F" tot_len %"U16_F"\n", p->len, p->tot_len));
276 
277   iphdr = p->payload;
278 
279 
280   if (dest != IP_HDRINCL) {
281     LWIP_DEBUGF(IP_DEBUG, ("!IP_HDRLINCL\n"));
282     iphdr->hoplim = ttl;
283     iphdr->nexthdr = proto;
284     iphdr->len = htons(p->tot_len - IP_HLEN);
285     ip_addr_set(&(iphdr->dest), dest);
286 
287     iphdr->v = 6;
288 
289     if (ip_addr_isany(src)) {
290       ip_addr_set(&(iphdr->src), &(netif->ip_addr));
291     } else {
292       ip_addr_set(&(iphdr->src), src);
293     }
294 
295   } else {
296     dest = &(iphdr->dest);
297   }
298 
299   IP_STATS_INC(ip.xmit);
300 
301   LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c (len %"U16_F")\n", netif->name[0], netif->name[1], p->tot_len));
302 #if IP_DEBUG
303   ip_debug_print(p);
304 #endif /* IP_DEBUG */
305 
306   PERF_STOP("ip_output_if");
307   return netif->output(netif, p, dest);
308 }
309 
310 /* ip_output:
311  *
312  * Simple interface to ip_output_if. It finds the outgoing network interface and
313  * calls upon ip_output_if to do the actual work.
314  */
315 
316 err_t
ip_output(struct pbuf * p,struct ip_addr * src,struct ip_addr * dest,u8_t ttl,u8_t proto)317 ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
318     u8_t ttl, u8_t proto)
319 {
320   struct netif *netif;
321   if ((netif = ip_route(dest)) == NULL) {
322     LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
323     IP_STATS_INC(ip.rterr);
324     return ERR_RTE;
325   }
326 
327   return ip_output_if (p, src, dest, ttl, proto, netif);
328 }
329 
330 #if LWIP_NETIF_HWADDRHINT
331 err_t
ip_output_hinted(struct pbuf * p,struct ip_addr * src,struct ip_addr * dest,u8_t ttl,u8_t tos,u8_t proto,u8_t * addr_hint)332 ip_output_hinted(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
333           u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
334 {
335   struct netif *netif;
336   err_t err;
337 
338   if ((netif = ip_route(dest)) == NULL) {
339     LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
340     IP_STATS_INC(ip.rterr);
341     return ERR_RTE;
342   }
343 
344   LWIP_NETIF_HWADDRHINT(netif, addr_hint);
345   err = ip_output_if(p, src, dest, ttl, tos, proto, netif);
346   LWIP_NETIF_HWADDRHINT(netif, NULL);
347 
348   return err;
349 }
350 #endif /* LWIP_NETIF_HWADDRHINT*/
351 
352 #if IP_DEBUG
353 void
ip_debug_print(struct pbuf * p)354 ip_debug_print(struct pbuf *p)
355 {
356   struct ip_hdr *iphdr = p->payload;
357 
358   LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
359   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
360   LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |  %"X16_F"%"X16_F"  |      %"X16_F"%"X16_F"           | (v, traffic class, flow label)\n",
361         iphdr->v,
362         iphdr->tclass1, iphdr->tclass2,
363         iphdr->flow1, iphdr->flow2));
364   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
365   LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      | %2"U16_F"  |  %2"U16_F"   | (len, nexthdr, hoplim)\n",
366         ntohs(iphdr->len),
367         iphdr->nexthdr,
368         iphdr->hoplim));
369   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
370   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (src)\n",
371         (ntohl(iphdr->src.addr[0]) >> 16) & 0xffff,
372         ntohl(iphdr->src.addr[0]) & 0xffff));
373   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (src)\n",
374         (ntohl(iphdr->src.addr[1]) >> 16) & 0xffff,
375         ntohl(iphdr->src.addr[1]) & 0xffff));
376   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (src)\n",
377         (ntohl(iphdr->src.addr[2]) >> 16) & 0xffff,
378         ntohl(iphdr->src.addr[2]) & 0xffff));
379   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (src)\n",
380         (ntohl(iphdr->src.addr[3]) >> 16) & 0xffff,
381         ntohl(iphdr->src.addr[3]) & 0xffff));
382   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
383   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (dest)\n",
384         (ntohl(iphdr->dest.addr[0]) >> 16) & 0xffff,
385         ntohl(iphdr->dest.addr[0]) & 0xffff));
386   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (dest)\n",
387         (ntohl(iphdr->dest.addr[1]) >> 16) & 0xffff,
388         ntohl(iphdr->dest.addr[1]) & 0xffff));
389   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (dest)\n",
390         (ntohl(iphdr->dest.addr[2]) >> 16) & 0xffff,
391         ntohl(iphdr->dest.addr[2]) & 0xffff));
392   LWIP_DEBUGF(IP_DEBUG, ("|       %4"X32_F"      |       %4"X32_F"     | (dest)\n",
393         (ntohl(iphdr->dest.addr[3]) >> 16) & 0xffff,
394         ntohl(iphdr->dest.addr[3]) & 0xffff));
395   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
396 }
397 #endif /* IP_DEBUG */
398