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ip.c

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00001 /**
00002  * @file
00003  * This is the IPv4 layer implementation for incoming and outgoing IP traffic.
00004  * 
00005  * @see ip_frag.c
00006  *
00007  */
00008 
00009 /*
00010  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00011  * All rights reserved.
00012  *
00013  * Redistribution and use in source and binary forms, with or without modification,
00014  * are permitted provided that the following conditions are met:
00015  *
00016  * 1. Redistributions of source code must retain the above copyright notice,
00017  *    this list of conditions and the following disclaimer.
00018  * 2. Redistributions in binary form must reproduce the above copyright notice,
00019  *    this list of conditions and the following disclaimer in the documentation
00020  *    and/or other materials provided with the distribution.
00021  * 3. The name of the author may not be used to endorse or promote products
00022  *    derived from this software without specific prior written permission.
00023  *
00024  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00025  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00026  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00027  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00028  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00029  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00030  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00031  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00032  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00033  * OF SUCH DAMAGE.
00034  *
00035  * This file is part of the lwIP TCP/IP stack.
00036  *
00037  * Author: Adam Dunkels <adam@sics.se>
00038  *
00039  */
00040 
00041 #include "lwip/opt.h"
00042 #include "lwip/ip.h"
00043 #include "lwip/def.h"
00044 #include "lwip/mem.h"
00045 #include "lwip/ip_frag.h"
00046 #include "lwip/inet_chksum.h"
00047 #include "lwip/netif.h"
00048 #include "lwip/icmp.h"
00049 #include "lwip/igmp.h"
00050 #include "lwip/raw.h"
00051 #include "lwip/udp.h"
00052 #include "lwip/tcp_impl.h"
00053 #include "lwip/snmp.h"
00054 #include "lwip/dhcp.h "
00055 #include "lwip/autoip.h"
00056 #include "lwip/stats.h"
00057 #include "arch/perf.h"
00058 
00059 #include <string.h>
00060 
00061 /** Set this to 0 in the rare case of wanting to call an extra function to
00062  * generate the IP checksum (in contrast to calculating it on-the-fly). */
00063 #ifndef LWIP_INLINE_IP_CHKSUM
00064 #define LWIP_INLINE_IP_CHKSUM   1
00065 #endif
00066 #if LWIP_INLINE_IP_CHKSUM && CHECKSUM_GEN_IP
00067 #define CHECKSUM_GEN_IP_INLINE  1
00068 #else
00069 #define CHECKSUM_GEN_IP_INLINE  0
00070 #endif
00071 
00072 #if LWIP_DHCP || defined(LWIP_IP_ACCEPT_UDP_PORT)
00073 #define IP_ACCEPT_LINK_LAYER_ADDRESSING 1
00074 
00075 /** Some defines for DHCP to let link-layer-addressed packets through while the
00076  * netif is down.
00077  * To use this in your own application/protocol, define LWIP_IP_ACCEPT_UDP_PORT
00078  * to return 1 if the port is accepted and 0 if the port is not accepted.
00079  */
00080 #if LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT)
00081 /* accept DHCP client port and custom port */
00082 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (((port) == PP_NTOHS(DHCP_CLIENT_PORT)) \
00083          || (LWIP_IP_ACCEPT_UDP_PORT(port)))
00084 #elif defined(LWIP_IP_ACCEPT_UDP_PORT) /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
00085 /* accept custom port only */
00086 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (LWIP_IP_ACCEPT_UDP_PORT(dst_port))
00087 #else /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
00088 /* accept DHCP client port only */
00089 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) ((port) == PP_NTOHS(DHCP_CLIENT_PORT))
00090 #endif /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
00091 
00092 #else /* LWIP_DHCP */
00093 #define IP_ACCEPT_LINK_LAYER_ADDRESSING 0
00094 #endif /* LWIP_DHCP */
00095 
00096 /**
00097  * The interface that provided the packet for the current callback
00098  * invocation.
00099  */
00100 struct netif *current_netif;
00101 
00102 /**
00103  * Header of the input packet currently being processed.
00104  */
00105 const struct ip_hdr *current_header;
00106 /** Source IP address of current_header */
00107 ip_addr_t current_iphdr_src;
00108 /** Destination IP address of current_header */
00109 ip_addr_t current_iphdr_dest;
00110 
00111 /** The IP header ID of the next outgoing IP packet */
00112 static u16_t ip_id;
00113 
00114 /**
00115  * Finds the appropriate network interface for a given IP address. It
00116  * searches the list of network interfaces linearly. A match is found
00117  * if the masked IP address of the network interface equals the masked
00118  * IP address given to the function.
00119  *
00120  * @param dest the destination IP address for which to find the route
00121  * @return the netif on which to send to reach dest
00122  */
00123 struct netif *
00124 ip_route(ip_addr_t *dest)
00125 {
00126   struct netif *netif;
00127 
00128   /* iterate through netifs */
00129   for(netif = netif_list; netif != NULL; netif = netif->next) {
00130     /* network mask matches? */
00131     if (netif_is_up(netif)) {
00132       if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {
00133         /* return netif on which to forward IP packet */
00134         return netif;
00135       }
00136     }
00137   }
00138   if ((netif_default == NULL) || (!netif_is_up(netif_default))) {
00139     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_route: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00140       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00141     IP_STATS_INC(ip.rterr);
00142     snmp_inc_ipoutnoroutes();
00143     return NULL;
00144   }
00145   /* no matching netif found, use default netif */
00146   return netif_default;
00147 }
00148 
00149 #if IP_FORWARD
00150 /**
00151  * Forwards an IP packet. It finds an appropriate route for the
00152  * packet, decrements the TTL value of the packet, adjusts the
00153  * checksum and outputs the packet on the appropriate interface.
00154  *
00155  * @param p the packet to forward (p->payload points to IP header)
00156  * @param iphdr the IP header of the input packet
00157  * @param inp the netif on which this packet was received
00158  */
00159 static void
00160 ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
00161 {
00162   struct netif *netif;
00163 
00164   PERF_START;
00165 
00166   /* RFC3927 2.7: do not forward link-local addresses */
00167   if (ip_addr_islinklocal(&current_iphdr_dest)) {
00168     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not forwarding LLA %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00169       ip4_addr1_16(&current_iphdr_dest), ip4_addr2_16(&current_iphdr_dest),
00170       ip4_addr3_16(&current_iphdr_dest), ip4_addr4_16(&current_iphdr_dest)));
00171     goto return_noroute;
00172   }
00173 
00174   /* Find network interface where to forward this IP packet to. */
00175   netif = ip_route(&current_iphdr_dest);
00176   if (netif == NULL) {
00177     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for %"U16_F".%"U16_F".%"U16_F".%"U16_F" found\n",
00178       ip4_addr1_16(&current_iphdr_dest), ip4_addr2_16(&current_iphdr_dest),
00179       ip4_addr3_16(&current_iphdr_dest), ip4_addr4_16(&current_iphdr_dest)));
00180     goto return_noroute;
00181   }
00182   /* Do not forward packets onto the same network interface on which
00183    * they arrived. */
00184   if (netif == inp) {
00185     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));
00186     goto return_noroute;
00187   }
00188 
00189   /* decrement TTL */
00190   IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
00191   /* send ICMP if TTL == 0 */
00192   if (IPH_TTL(iphdr) == 0) {
00193     snmp_inc_ipinhdrerrors();
00194 #if LWIP_ICMP
00195     /* Don't send ICMP messages in response to ICMP messages */
00196     if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
00197       icmp_time_exceeded(p, ICMP_TE_TTL);
00198     }
00199 #endif /* LWIP_ICMP */
00200     return;
00201   }
00202 
00203   /* Incrementally update the IP checksum. */
00204   if (IPH_CHKSUM(iphdr) >= PP_HTONS(0xffffU - 0x100)) {
00205     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1);
00206   } else {
00207     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100));
00208   }
00209 
00210   LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00211     ip4_addr1_16(&current_iphdr_dest), ip4_addr2_16(&current_iphdr_dest),
00212     ip4_addr3_16(&current_iphdr_dest), ip4_addr4_16(&current_iphdr_dest)));
00213 
00214   IP_STATS_INC(ip.fw);
00215   IP_STATS_INC(ip.xmit);
00216   snmp_inc_ipforwdatagrams();
00217 
00218   PERF_STOP("ip_forward");
00219   /* transmit pbuf on chosen interface */
00220   netif->output(netif, p, &current_iphdr_dest);
00221   return;
00222 return_noroute:
00223   snmp_inc_ipoutnoroutes();
00224 }
00225 #endif /* IP_FORWARD */
00226 
00227 /**
00228  * This function is called by the network interface device driver when
00229  * an IP packet is received. The function does the basic checks of the
00230  * IP header such as packet size being at least larger than the header
00231  * size etc. If the packet was not destined for us, the packet is
00232  * forwarded (using ip_forward). The IP checksum is always checked.
00233  *
00234  * Finally, the packet is sent to the upper layer protocol input function.
00235  * 
00236  * @param p the received IP packet (p->payload points to IP header)
00237  * @param inp the netif on which this packet was received
00238  * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
00239  *         processed, but currently always returns ERR_OK)
00240  */
00241 err_t
00242 ip_input(struct pbuf *p, struct netif *inp)
00243 {
00244   struct ip_hdr *iphdr;
00245   struct netif *netif;
00246   u16_t iphdr_hlen;
00247   u16_t iphdr_len;
00248 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00249   int check_ip_src=1;
00250 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00251 
00252   IP_STATS_INC(ip.recv);
00253   snmp_inc_ipinreceives();
00254 
00255   /* identify the IP header */
00256   iphdr = (struct ip_hdr *)p->payload;
00257   if (IPH_V(iphdr) != 4) {
00258     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_WARNING, ("IP packet dropped due to bad version number %"U16_F"\n", IPH_V(iphdr)));
00259     ip_debug_print(p);
00260     pbuf_free(p);
00261     IP_STATS_INC(ip.err);
00262     IP_STATS_INC(ip.drop);
00263     snmp_inc_ipinhdrerrors();
00264     return ERR_OK;
00265   }
00266 
00267   /* obtain IP header length in number of 32-bit words */
00268   iphdr_hlen = IPH_HL(iphdr);
00269   /* calculate IP header length in bytes */
00270   iphdr_hlen *= 4;
00271   /* obtain ip length in bytes */
00272   iphdr_len = ntohs(IPH_LEN(iphdr));
00273 
00274   /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
00275   if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len)) {
00276     if (iphdr_hlen > p->len) {
00277       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00278         ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
00279         iphdr_hlen, p->len));
00280     }
00281     if (iphdr_len > p->tot_len) {
00282       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00283         ("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), IP packet dropped.\n",
00284         iphdr_len, p->tot_len));
00285     }
00286     /* free (drop) packet pbufs */
00287     pbuf_free(p);
00288     IP_STATS_INC(ip.lenerr);
00289     IP_STATS_INC(ip.drop);
00290     snmp_inc_ipindiscards();
00291     return ERR_OK;
00292   }
00293 
00294   /* verify checksum */
00295 #if CHECKSUM_CHECK_IP
00296   if (inet_chksum(iphdr, iphdr_hlen) != 0) {
00297 
00298     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00299       ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
00300     ip_debug_print(p);
00301     pbuf_free(p);
00302     IP_STATS_INC(ip.chkerr);
00303     IP_STATS_INC(ip.drop);
00304     snmp_inc_ipinhdrerrors();
00305     return ERR_OK;
00306   }
00307 #endif
00308 
00309   /* Trim pbuf. This should have been done at the netif layer,
00310    * but we'll do it anyway just to be sure that its done. */
00311   pbuf_realloc(p, iphdr_len);
00312 
00313   /* copy IP addresses to aligned ip_addr_t */
00314   ip_addr_copy(current_iphdr_dest, iphdr->dest);
00315   ip_addr_copy(current_iphdr_src, iphdr->src);
00316 
00317   /* match packet against an interface, i.e. is this packet for us? */
00318 #if LWIP_IGMP
00319   if (ip_addr_ismulticast(&current_iphdr_dest)) {
00320     if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, &current_iphdr_dest))) {
00321       netif = inp;
00322     } else {
00323       netif = NULL;
00324     }
00325   } else
00326 #endif /* LWIP_IGMP */
00327   {
00328     /* start trying with inp. if that's not acceptable, start walking the
00329        list of configured netifs.
00330        'first' is used as a boolean to mark whether we started walking the list */
00331     int first = 1;
00332     netif = inp;
00333     do {
00334       LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
00335           ip4_addr_get_u32(&iphdr->dest), ip4_addr_get_u32(&netif->ip_addr),
00336           ip4_addr_get_u32(&iphdr->dest) & ip4_addr_get_u32(&netif->netmask),
00337           ip4_addr_get_u32(&netif->ip_addr) & ip4_addr_get_u32(&netif->netmask),
00338           ip4_addr_get_u32(&iphdr->dest) & ~ip4_addr_get_u32(&netif->netmask)));
00339 
00340       /* interface is up and configured? */
00341       if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) {
00342         /* unicast to this interface address? */
00343         if (ip_addr_cmp(&current_iphdr_dest, &(netif->ip_addr)) ||
00344             /* or broadcast on this interface network address? */
00345             ip_addr_isbroadcast(&current_iphdr_dest, netif)) {
00346           LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
00347               netif->name[0], netif->name[1]));
00348           /* break out of for loop */
00349           break;
00350         }
00351 #if LWIP_AUTOIP
00352         /* connections to link-local addresses must persist after changing
00353            the netif's address (RFC3927 ch. 1.9) */
00354         if ((netif->autoip != NULL) &&
00355             ip_addr_cmp(&current_iphdr_dest, &(netif->autoip->llipaddr))) {
00356           LWIP_DEBUGF(IP_DEBUG, ("ip_input: LLA packet accepted on interface %c%c\n",
00357               netif->name[0], netif->name[1]));
00358           /* break out of for loop */
00359           break;
00360         }
00361 #endif /* LWIP_AUTOIP */
00362       }
00363       if (first) {
00364         first = 0;
00365         netif = netif_list;
00366       } else {
00367         netif = netif->next;
00368       }
00369       if (netif == inp) {
00370         netif = netif->next;
00371       }
00372     } while(netif != NULL);
00373   }
00374 
00375 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00376   /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
00377    * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
00378    * According to RFC 1542 section 3.1.1, referred by RFC 2131).
00379    *
00380    * If you want to accept private broadcast communication while a netif is down,
00381    * define LWIP_IP_ACCEPT_UDP_PORT(dst_port), e.g.:
00382    *
00383    * #define LWIP_IP_ACCEPT_UDP_PORT(dst_port) ((dst_port) == PP_NTOHS(12345))
00384    */
00385   if (netif == NULL) {
00386     /* remote port is DHCP server? */
00387     if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
00388       struct udp_hdr *udphdr = (struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen);
00389       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
00390         ntohs(udphdr->dest)));
00391       if (IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(udphdr->dest)) {
00392         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: DHCP packet accepted.\n"));
00393         netif = inp;
00394         check_ip_src = 0;
00395       }
00396     }
00397   }
00398 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00399 
00400   /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
00401 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00402   /* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
00403   if (check_ip_src && !ip_addr_isany(&current_iphdr_src))
00404 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00405   {  if ((ip_addr_isbroadcast(&current_iphdr_src, inp)) ||
00406          (ip_addr_ismulticast(&current_iphdr_src))) {
00407       /* packet source is not valid */
00408       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("ip_input: packet source is not valid.\n"));
00409       /* free (drop) packet pbufs */
00410       pbuf_free(p);
00411       IP_STATS_INC(ip.drop);
00412       snmp_inc_ipinaddrerrors();
00413       snmp_inc_ipindiscards();
00414       return ERR_OK;
00415     }
00416   }
00417 
00418   /* packet not for us? */
00419   if (netif == NULL) {
00420     /* packet not for us, route or discard */
00421     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip_input: packet not for us.\n"));
00422 #if IP_FORWARD
00423     /* non-broadcast packet? */
00424     if (!ip_addr_isbroadcast(&current_iphdr_dest, inp)) {
00425       /* try to forward IP packet on (other) interfaces */
00426       ip_forward(p, iphdr, inp);
00427     } else
00428 #endif /* IP_FORWARD */
00429     {
00430       snmp_inc_ipinaddrerrors();
00431       snmp_inc_ipindiscards();
00432     }
00433     pbuf_free(p);
00434     return ERR_OK;
00435   }
00436   /* packet consists of multiple fragments? */
00437   if ((IPH_OFFSET(iphdr) & PP_HTONS(IP_OFFMASK | IP_MF)) != 0) {
00438 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
00439     LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04"X16_F" tot_len=%"U16_F" len=%"U16_F" MF=%"U16_F" offset=%"U16_F"), calling ip_reass()\n",
00440       ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
00441     /* reassemble the packet*/
00442     p = ip_reass(p);
00443     /* packet not fully reassembled yet? */
00444     if (p == NULL) {
00445       return ERR_OK;
00446     }
00447     iphdr = (struct ip_hdr *)p->payload;
00448 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
00449     pbuf_free(p);
00450     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
00451       ntohs(IPH_OFFSET(iphdr))));
00452     IP_STATS_INC(ip.opterr);
00453     IP_STATS_INC(ip.drop);
00454     /* unsupported protocol feature */
00455     snmp_inc_ipinunknownprotos();
00456     return ERR_OK;
00457 #endif /* IP_REASSEMBLY */
00458   }
00459 
00460 #if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
00461 
00462 #if LWIP_IGMP
00463   /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
00464   if((iphdr_hlen > IP_HLEN) &&  (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
00465 #else
00466   if (iphdr_hlen > IP_HLEN) {
00467 #endif /* LWIP_IGMP */
00468     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
00469     pbuf_free(p);
00470     IP_STATS_INC(ip.opterr);
00471     IP_STATS_INC(ip.drop);
00472     /* unsupported protocol feature */
00473     snmp_inc_ipinunknownprotos();
00474     return ERR_OK;
00475   }
00476 #endif /* IP_OPTIONS_ALLOWED == 0 */
00477 
00478   /* send to upper layers */
00479   LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
00480   ip_debug_print(p);
00481   LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
00482 
00483   current_netif = inp;
00484   current_header = iphdr;
00485 
00486 #if LWIP_RAW
00487   /* raw input did not eat the packet? */
00488   if (raw_input(p, inp) == 0)
00489 #endif /* LWIP_RAW */
00490   {
00491 
00492     switch (IPH_PROTO(iphdr)) {
00493 #if LWIP_UDP
00494     case IP_PROTO_UDP:
00495 #if LWIP_UDPLITE
00496     case IP_PROTO_UDPLITE:
00497 #endif /* LWIP_UDPLITE */
00498       snmp_inc_ipindelivers();
00499       udp_input(p, inp);
00500       break;
00501 #endif /* LWIP_UDP */
00502 #if LWIP_TCP
00503     case IP_PROTO_TCP:
00504       snmp_inc_ipindelivers();
00505       tcp_input(p, inp);
00506       break;
00507 #endif /* LWIP_TCP */
00508 #if LWIP_ICMP
00509     case IP_PROTO_ICMP:
00510       snmp_inc_ipindelivers();
00511       icmp_input(p, inp);
00512       break;
00513 #endif /* LWIP_ICMP */
00514 #if LWIP_IGMP
00515     case IP_PROTO_IGMP:
00516       igmp_input(p, inp, &current_iphdr_dest);
00517       break;
00518 #endif /* LWIP_IGMP */
00519     default:
00520 #if LWIP_ICMP
00521       /* send ICMP destination protocol unreachable unless is was a broadcast */
00522       if (!ip_addr_isbroadcast(&current_iphdr_dest, inp) &&
00523           !ip_addr_ismulticast(&current_iphdr_dest)) {
00524         p->payload = iphdr;
00525         icmp_dest_unreach(p, ICMP_DUR_PROTO);
00526       }
00527 #endif /* LWIP_ICMP */
00528       pbuf_free(p);
00529 
00530       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Unsupported transport protocol %"U16_F"\n", IPH_PROTO(iphdr)));
00531 
00532       IP_STATS_INC(ip.proterr);
00533       IP_STATS_INC(ip.drop);
00534       snmp_inc_ipinunknownprotos();
00535     }
00536   }
00537 
00538   current_netif = NULL;
00539   current_header = NULL;
00540   ip_addr_set_any(&current_iphdr_src);
00541   ip_addr_set_any(&current_iphdr_dest);
00542 
00543   return ERR_OK;
00544 }
00545 
00546 /**
00547  * Sends an IP packet on a network interface. This function constructs
00548  * the IP header and calculates the IP header checksum. If the source
00549  * IP address is NULL, the IP address of the outgoing network
00550  * interface is filled in as source address.
00551  * If the destination IP address is IP_HDRINCL, p is assumed to already
00552  * include an IP header and p->payload points to it instead of the data.
00553  *
00554  * @param p the packet to send (p->payload points to the data, e.g. next
00555             protocol header; if dest == IP_HDRINCL, p already includes an IP
00556             header and p->payload points to that IP header)
00557  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00558  *         IP  address of the netif used to send is used as source address)
00559  * @param dest the destination IP address to send the packet to
00560  * @param ttl the TTL value to be set in the IP header
00561  * @param tos the TOS value to be set in the IP header
00562  * @param proto the PROTOCOL to be set in the IP header
00563  * @param netif the netif on which to send this packet
00564  * @return ERR_OK if the packet was sent OK
00565  *         ERR_BUF if p doesn't have enough space for IP/LINK headers
00566  *         returns errors returned by netif->output
00567  *
00568  * @note ip_id: RFC791 "some host may be able to simply use
00569  *  unique identifiers independent of destination"
00570  */
00571 err_t
00572 ip_output_if(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
00573              u8_t ttl, u8_t tos,
00574              u8_t proto, struct netif *netif)
00575 {
00576 #if IP_OPTIONS_SEND
00577   return ip_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
00578 }
00579 
00580 /**
00581  * Same as ip_output_if() but with the possibility to include IP options:
00582  *
00583  * @ param ip_options pointer to the IP options, copied into the IP header
00584  * @ param optlen length of ip_options
00585  */
00586 err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
00587        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
00588        u16_t optlen)
00589 {
00590 #endif /* IP_OPTIONS_SEND */
00591   struct ip_hdr *iphdr;
00592   ip_addr_t dest_addr;
00593 #if CHECKSUM_GEN_IP_INLINE
00594   u32_t chk_sum = 0;
00595 #endif /* CHECKSUM_GEN_IP_INLINE */
00596 
00597   /* pbufs passed to IP must have a ref-count of 1 as their payload pointer
00598      gets altered as the packet is passed down the stack */
00599   LWIP_ASSERT("p->ref == 1", p->ref == 1);
00600 
00601   snmp_inc_ipoutrequests();
00602 
00603   /* Should the IP header be generated or is it already included in p? */
00604   if (dest != IP_HDRINCL) {
00605     u16_t ip_hlen = IP_HLEN;
00606 #if IP_OPTIONS_SEND
00607     u16_t optlen_aligned = 0;
00608     if (optlen != 0) {
00609 #if CHECKSUM_GEN_IP_INLINE
00610       int i;
00611 #endif /* CHECKSUM_GEN_IP_INLINE */
00612       /* round up to a multiple of 4 */
00613       optlen_aligned = ((optlen + 3) & ~3);
00614       ip_hlen += optlen_aligned;
00615       /* First write in the IP options */
00616       if (pbuf_header(p, optlen_aligned)) {
00617         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_output_if_opt: not enough room for IP options in pbuf\n"));
00618         IP_STATS_INC(ip.err);
00619         snmp_inc_ipoutdiscards();
00620         return ERR_BUF;
00621       }
00622       MEMCPY(p->payload, ip_options, optlen);
00623       if (optlen < optlen_aligned) {
00624         /* zero the remaining bytes */
00625         memset(((char*)p->payload) + optlen, 0, optlen_aligned - optlen);
00626       }
00627 #if CHECKSUM_GEN_IP_INLINE
00628       for (i = 0; i < optlen_aligned/2; i++) {
00629         chk_sum += ((u16_t*)p->payload)[i];
00630       }
00631 #endif /* CHECKSUM_GEN_IP_INLINE */
00632     }
00633 #endif /* IP_OPTIONS_SEND */
00634     /* generate IP header */
00635     if (pbuf_header(p, IP_HLEN)) {
00636       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_output: not enough room for IP header in pbuf\n"));
00637 
00638       IP_STATS_INC(ip.err);
00639       snmp_inc_ipoutdiscards();
00640       return ERR_BUF;
00641     }
00642 
00643     iphdr = (struct ip_hdr *)p->payload;
00644     LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
00645                (p->len >= sizeof(struct ip_hdr)));
00646 
00647     IPH_TTL_SET(iphdr, ttl);
00648     IPH_PROTO_SET(iphdr, proto);
00649 #if CHECKSUM_GEN_IP_INLINE
00650     chk_sum += LWIP_MAKE_U16(proto, ttl);
00651 #endif /* CHECKSUM_GEN_IP_INLINE */
00652 
00653     /* dest cannot be NULL here */
00654     ip_addr_copy(iphdr->dest, *dest);
00655 #if CHECKSUM_GEN_IP_INLINE
00656     chk_sum += ip4_addr_get_u32(&iphdr->dest) & 0xFFFF;
00657     chk_sum += ip4_addr_get_u32(&iphdr->dest) >> 16;
00658 #endif /* CHECKSUM_GEN_IP_INLINE */
00659 
00660     IPH_VHLTOS_SET(iphdr, 4, ip_hlen / 4, tos);
00661 #if CHECKSUM_GEN_IP_INLINE
00662     chk_sum += iphdr->_v_hl_tos;
00663 #endif /* CHECKSUM_GEN_IP_INLINE */
00664     IPH_LEN_SET(iphdr, htons(p->tot_len));
00665 #if CHECKSUM_GEN_IP_INLINE
00666     chk_sum += iphdr->_len;
00667 #endif /* CHECKSUM_GEN_IP_INLINE */
00668     IPH_OFFSET_SET(iphdr, 0);
00669     IPH_ID_SET(iphdr, htons(ip_id));
00670 #if CHECKSUM_GEN_IP_INLINE
00671     chk_sum += iphdr->_id;
00672 #endif /* CHECKSUM_GEN_IP_INLINE */
00673     ++ip_id;
00674 
00675     if (ip_addr_isany(src)) {
00676       ip_addr_copy(iphdr->src, netif->ip_addr);
00677     } else {
00678       /* src cannot be NULL here */
00679       ip_addr_copy(iphdr->src, *src);
00680     }
00681 
00682 #if CHECKSUM_GEN_IP_INLINE
00683     chk_sum += ip4_addr_get_u32(&iphdr->src) & 0xFFFF;
00684     chk_sum += ip4_addr_get_u32(&iphdr->src) >> 16;
00685     chk_sum = (chk_sum >> 16) + (chk_sum & 0xFFFF);
00686     chk_sum = (chk_sum >> 16) + chk_sum;
00687     chk_sum = ~chk_sum;
00688     iphdr->_chksum = chk_sum; /* network order */
00689 #else /* CHECKSUM_GEN_IP_INLINE */
00690     IPH_CHKSUM_SET(iphdr, 0);
00691 #if CHECKSUM_GEN_IP
00692     IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
00693 #endif
00694 #endif /* CHECKSUM_GEN_IP_INLINE */
00695   } else {
00696     /* IP header already included in p */
00697     iphdr = (struct ip_hdr *)p->payload;
00698     ip_addr_copy(dest_addr, iphdr->dest);
00699     dest = &dest_addr;
00700   }
00701 
00702   IP_STATS_INC(ip.xmit);
00703 
00704   LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
00705   ip_debug_print(p);
00706 
00707 #if ENABLE_LOOPBACK
00708   if (ip_addr_cmp(dest, &netif->ip_addr)) {
00709     /* Packet to self, enqueue it for loopback */
00710     LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
00711     return netif_loop_output(netif, p, dest);
00712   }
00713 #if LWIP_IGMP
00714   if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
00715     netif_loop_output(netif, p, dest);
00716   }
00717 #endif /* LWIP_IGMP */
00718 #endif /* ENABLE_LOOPBACK */
00719 #if IP_FRAG
00720   /* don't fragment if interface has mtu set to 0 [loopif] */
00721   if (netif->mtu && (p->tot_len > netif->mtu)) {
00722     return ip_frag(p, netif, dest);
00723   }
00724 #endif /* IP_FRAG */
00725 
00726   LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
00727   return netif->output(netif, p, dest);
00728 }
00729 
00730 /**
00731  * Simple interface to ip_output_if. It finds the outgoing network
00732  * interface and calls upon ip_output_if to do the actual work.
00733  *
00734  * @param p the packet to send (p->payload points to the data, e.g. next
00735             protocol header; if dest == IP_HDRINCL, p already includes an IP
00736             header and p->payload points to that IP header)
00737  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00738  *         IP  address of the netif used to send is used as source address)
00739  * @param dest the destination IP address to send the packet to
00740  * @param ttl the TTL value to be set in the IP header
00741  * @param tos the TOS value to be set in the IP header
00742  * @param proto the PROTOCOL to be set in the IP header
00743  *
00744  * @return ERR_RTE if no route is found
00745  *         see ip_output_if() for more return values
00746  */
00747 err_t
00748 ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
00749           u8_t ttl, u8_t tos, u8_t proto)
00750 {
00751   struct netif *netif;
00752 
00753   /* pbufs passed to IP must have a ref-count of 1 as their payload pointer
00754      gets altered as the packet is passed down the stack */
00755   LWIP_ASSERT("p->ref == 1", p->ref == 1);
00756 
00757   if ((netif = ip_route(dest)) == NULL) {
00758     LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00759       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00760     IP_STATS_INC(ip.rterr);
00761     return ERR_RTE;
00762   }
00763 
00764   return ip_output_if(p, src, dest, ttl, tos, proto, netif);
00765 }
00766 
00767 #if LWIP_NETIF_HWADDRHINT
00768 /** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
00769  *  before calling ip_output_if.
00770  *
00771  * @param p the packet to send (p->payload points to the data, e.g. next
00772             protocol header; if dest == IP_HDRINCL, p already includes an IP
00773             header and p->payload points to that IP header)
00774  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00775  *         IP  address of the netif used to send is used as source address)
00776  * @param dest the destination IP address to send the packet to
00777  * @param ttl the TTL value to be set in the IP header
00778  * @param tos the TOS value to be set in the IP header
00779  * @param proto the PROTOCOL to be set in the IP header
00780  * @param addr_hint address hint pointer set to netif->addr_hint before
00781  *        calling ip_output_if()
00782  *
00783  * @return ERR_RTE if no route is found
00784  *         see ip_output_if() for more return values
00785  */
00786 err_t
00787 ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
00788           u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
00789 {
00790   struct netif *netif;
00791   err_t err;
00792 
00793   /* pbufs passed to IP must have a ref-count of 1 as their payload pointer
00794      gets altered as the packet is passed down the stack */
00795   LWIP_ASSERT("p->ref == 1", p->ref == 1);
00796 
00797   if ((netif = ip_route(dest)) == NULL) {
00798     LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00799       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00800     IP_STATS_INC(ip.rterr);
00801     return ERR_RTE;
00802   }
00803 
00804   netif->addr_hint = addr_hint;
00805   err = ip_output_if(p, src, dest, ttl, tos, proto, netif);
00806   netif->addr_hint = NULL;
00807 
00808   return err;
00809 }
00810 #endif /* LWIP_NETIF_HWADDRHINT*/
00811 
00812 #if IP_DEBUG
00813 /* Print an IP header by using LWIP_DEBUGF
00814  * @param p an IP packet, p->payload pointing to the IP header
00815  */
00816 void
00817 ip_debug_print(struct pbuf *p)
00818 {
00819   struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
00820   u8_t *payload;
00821 
00822   payload = (u8_t *)iphdr + IP_HLEN;
00823 
00824   LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
00825   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00826   LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" |  0x%02"X16_F" |     %5"U16_F"     | (v, hl, tos, len)\n",
00827                     IPH_V(iphdr),
00828                     IPH_HL(iphdr),
00829                     IPH_TOS(iphdr),
00830                     ntohs(IPH_LEN(iphdr))));
00831   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00832   LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      |%"U16_F"%"U16_F"%"U16_F"|    %4"U16_F"   | (id, flags, offset)\n",
00833                     ntohs(IPH_ID(iphdr)),
00834                     ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
00835                     ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
00836                     ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
00837                     ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
00838   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00839   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |    0x%04"X16_F"     | (ttl, proto, chksum)\n",
00840                     IPH_TTL(iphdr),
00841                     IPH_PROTO(iphdr),
00842                     ntohs(IPH_CHKSUM(iphdr))));
00843   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00844   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (src)\n",
00845                     ip4_addr1_16(&iphdr->src),
00846                     ip4_addr2_16(&iphdr->src),
00847                     ip4_addr3_16(&iphdr->src),
00848                     ip4_addr4_16(&iphdr->src)));
00849   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00850   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (dest)\n",
00851                     ip4_addr1_16(&iphdr->dest),
00852                     ip4_addr2_16(&iphdr->dest),
00853                     ip4_addr3_16(&iphdr->dest),
00854                     ip4_addr4_16(&iphdr->dest)));
00855   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00856 }
00857 #endif /* IP_DEBUG */