lwip_ip4.c

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 
00043 #if LWIP_IPV4
00044 
00045 #include "lwip/ip.h"
00046 #include "lwip/def.h"
00047 #include "lwip/mem.h"
00048 #include "lwip/ip4_frag.h"
00049 #include "lwip/inet_chksum.h"
00050 #include "lwip/netif.h"
00051 #include "lwip/icmp.h"
00052 #include "lwip/igmp.h"
00053 #include "lwip/raw.h"
00054 #include "lwip/udp.h"
00055 #include "lwip/priv/tcp_priv.h"
00056 #include "lwip/autoip.h"
00057 #include "lwip/stats.h"
00058 #include "lwip/prot/dhcp.h"
00059 
00060 #include <string.h>
00061 
00062 /** Set this to 0 in the rare case of wanting to call an extra function to
00063  * generate the IP checksum (in contrast to calculating it on-the-fly). */
00064 #ifndef LWIP_INLINE_IP_CHKSUM
00065 #if LWIP_CHECKSUM_CTRL_PER_NETIF
00066 #define LWIP_INLINE_IP_CHKSUM   0
00067 #else /* LWIP_CHECKSUM_CTRL_PER_NETIF */
00068 #define LWIP_INLINE_IP_CHKSUM   1
00069 #endif /* LWIP_CHECKSUM_CTRL_PER_NETIF */
00070 #endif
00071 
00072 #if LWIP_INLINE_IP_CHKSUM && CHECKSUM_GEN_IP
00073 #define CHECKSUM_GEN_IP_INLINE  1
00074 #else
00075 #define CHECKSUM_GEN_IP_INLINE  0
00076 #endif
00077 
00078 #if LWIP_DHCP || defined(LWIP_IP_ACCEPT_UDP_PORT)
00079 #define IP_ACCEPT_LINK_LAYER_ADDRESSING 1
00080 
00081 /** Some defines for DHCP to let link-layer-addressed packets through while the
00082  * netif is down.
00083  * To use this in your own application/protocol, define LWIP_IP_ACCEPT_UDP_PORT(port)
00084  * to return 1 if the port is accepted and 0 if the port is not accepted.
00085  */
00086 #if LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT)
00087 /* accept DHCP client port and custom port */
00088 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (((port) == PP_NTOHS(DHCP_CLIENT_PORT)) \
00089          || (LWIP_IP_ACCEPT_UDP_PORT(port)))
00090 #elif defined(LWIP_IP_ACCEPT_UDP_PORT) /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
00091 /* accept custom port only */
00092 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) (LWIP_IP_ACCEPT_UDP_PORT(port))
00093 #else /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
00094 /* accept DHCP client port only */
00095 #define IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(port) ((port) == PP_NTOHS(DHCP_CLIENT_PORT))
00096 #endif /* LWIP_DHCP && defined(LWIP_IP_ACCEPT_UDP_PORT) */
00097 
00098 #else /* LWIP_DHCP */
00099 #define IP_ACCEPT_LINK_LAYER_ADDRESSING 0
00100 #endif /* LWIP_DHCP */
00101 
00102 /** The IP header ID of the next outgoing IP packet */
00103 static u16_t ip_id;
00104 
00105 #if LWIP_MULTICAST_TX_OPTIONS
00106 /** The default netif used for multicast */
00107 static struct netif* ip4_default_multicast_netif;
00108 
00109 /**
00110  * @ingroup ip4
00111  * Set a default netif for IPv4 multicast. */
00112 void
00113 ip4_set_default_multicast_netif(struct netif* default_multicast_netif)
00114 {
00115   ip4_default_multicast_netif = default_multicast_netif;
00116 }
00117 #endif /* LWIP_MULTICAST_TX_OPTIONS */
00118 
00119 #ifdef LWIP_HOOK_IP4_ROUTE_SRC
00120 /**
00121  * Source based IPv4 routing must be fully implemented in
00122  * LWIP_HOOK_IP4_ROUTE_SRC(). This function only provides he parameters.
00123  */
00124 struct netif *
00125 ip4_route_src(const ip4_addr_t *dest, const ip4_addr_t *src)
00126 {
00127   if (src != NULL) {
00128     /* when src==NULL, the hook is called from ip4_route(dest) */
00129     struct netif *netif = LWIP_HOOK_IP4_ROUTE_SRC(dest, src);
00130     if (netif != NULL) {
00131       return netif;
00132     }
00133   }
00134   return ip4_route(dest);
00135 }
00136 #endif /* LWIP_HOOK_IP4_ROUTE_SRC */
00137 
00138 /**
00139  * Finds the appropriate network interface for a given IP address. It
00140  * searches the list of network interfaces linearly. A match is found
00141  * if the masked IP address of the network interface equals the masked
00142  * IP address given to the function.
00143  *
00144  * @param dest the destination IP address for which to find the route
00145  * @return the netif on which to send to reach dest
00146  */
00147 struct netif *
00148 ip4_route(const ip4_addr_t *dest)
00149 {
00150   struct netif *netif;
00151 
00152 #if LWIP_MULTICAST_TX_OPTIONS
00153   /* Use administratively selected interface for multicast by default */
00154   if (ip4_addr_ismulticast(dest) && ip4_default_multicast_netif) {
00155     return ip4_default_multicast_netif;
00156   }
00157 #endif /* LWIP_MULTICAST_TX_OPTIONS */
00158 
00159   /* iterate through netifs */
00160   for (netif = netif_list; netif != NULL; netif = netif->next) {
00161     /* is the netif up, does it have a link and a valid address? */
00162     if (netif_is_up(netif) && netif_is_link_up(netif) && !ip4_addr_isany_val(*netif_ip4_addr(netif))) {
00163       /* network mask matches? */
00164       if (ip4_addr_netcmp(dest, netif_ip4_addr(netif), netif_ip4_netmask(netif))) {
00165         /* return netif on which to forward IP packet */
00166         return netif;
00167       }
00168       /* gateway matches on a non broadcast interface? (i.e. peer in a point to point interface) */
00169       if (((netif->flags & NETIF_FLAG_BROADCAST) == 0) && ip4_addr_cmp(dest, netif_ip4_gw(netif))) {
00170         /* return netif on which to forward IP packet */
00171         return netif;
00172       }
00173     }
00174   }
00175 
00176 #if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
00177   /* loopif is disabled, looopback traffic is passed through any netif */
00178   if (ip4_addr_isloopback(dest)) {
00179     /* don't check for link on loopback traffic */
00180     if (netif_default != NULL && netif_is_up(netif_default)) {
00181       return netif_default;
00182     }
00183     /* default netif is not up, just use any netif for loopback traffic */
00184     for (netif = netif_list; netif != NULL; netif = netif->next) {
00185       if (netif_is_up(netif)) {
00186         return netif;
00187       }
00188     }
00189     return NULL;
00190   }
00191 #endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
00192 
00193 #ifdef LWIP_HOOK_IP4_ROUTE_SRC
00194   netif = LWIP_HOOK_IP4_ROUTE_SRC(dest, NULL);
00195   if (netif != NULL) {
00196     return netif;
00197   }
00198 #elif defined(LWIP_HOOK_IP4_ROUTE)
00199   netif = LWIP_HOOK_IP4_ROUTE(dest);
00200   if (netif != NULL) {
00201     return netif;
00202   }
00203 #endif
00204 
00205   if ((netif_default == NULL) || !netif_is_up(netif_default) || !netif_is_link_up(netif_default) ||
00206       ip4_addr_isany_val(*netif_ip4_addr(netif_default))) {
00207     /* No matching netif found and default netif is not usable.
00208        If this is not good enough for you, use LWIP_HOOK_IP4_ROUTE() */
00209     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_route: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00210       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00211     IP_STATS_INC(ip.rterr);
00212     MIB2_STATS_INC(mib2.ipoutnoroutes);
00213     return NULL;
00214   }
00215 
00216   return netif_default;
00217 }
00218 
00219 #if IP_FORWARD
00220 /**
00221  * Determine whether an IP address is in a reserved set of addresses
00222  * that may not be forwarded, or whether datagrams to that destination
00223  * may be forwarded.
00224  * @param p the packet to forward
00225  * @return 1: can forward 0: discard
00226  */
00227 static int
00228 ip4_canforward(struct pbuf *p)
00229 {
00230   u32_t addr = lwip_htonl(ip4_addr_get_u32(ip4_current_dest_addr()));
00231 
00232   if (p->flags & PBUF_FLAG_LLBCAST) {
00233     /* don't route link-layer broadcasts */
00234     return 0;
00235   }
00236   if ((p->flags & PBUF_FLAG_LLMCAST) && !IP_MULTICAST(addr)) {
00237     /* don't route link-layer multicasts unless the destination address is an IP
00238        multicast address */
00239     return 0;
00240   }
00241   if (IP_EXPERIMENTAL(addr)) {
00242     return 0;
00243   }
00244   if (IP_CLASSA(addr)) {
00245     u32_t net = addr & IP_CLASSA_NET;
00246     if ((net == 0) || (net == ((u32_t)IP_LOOPBACKNET << IP_CLASSA_NSHIFT))) {
00247       /* don't route loopback packets */
00248       return 0;
00249     }
00250   }
00251   return 1;
00252 }
00253 
00254 /**
00255  * Forwards an IP packet. It finds an appropriate route for the
00256  * packet, decrements the TTL value of the packet, adjusts the
00257  * checksum and outputs the packet on the appropriate interface.
00258  *
00259  * @param p the packet to forward (p->payload points to IP header)
00260  * @param iphdr the IP header of the input packet
00261  * @param inp the netif on which this packet was received
00262  */
00263 static void
00264 ip4_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
00265 {
00266   struct netif *netif;
00267 
00268   PERF_START;
00269   LWIP_UNUSED_ARG(inp);
00270 
00271   if (!ip4_canforward(p)) {
00272     goto return_noroute;
00273   }
00274 
00275   /* RFC3927 2.7: do not forward link-local addresses */
00276   if (ip4_addr_islinklocal(ip4_current_dest_addr())) {
00277     LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: not forwarding LLA %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00278       ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
00279       ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
00280     goto return_noroute;
00281   }
00282 
00283   /* Find network interface where to forward this IP packet to. */
00284   netif = ip4_route_src(ip4_current_dest_addr(), ip4_current_src_addr());
00285   if (netif == NULL) {
00286     LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: no forwarding route for %"U16_F".%"U16_F".%"U16_F".%"U16_F" found\n",
00287       ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
00288       ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
00289     /* @todo: send ICMP_DUR_NET? */
00290     goto return_noroute;
00291   }
00292 #if !IP_FORWARD_ALLOW_TX_ON_RX_NETIF
00293   /* Do not forward packets onto the same network interface on which
00294    * they arrived. */
00295   if (netif == inp) {
00296     LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: not bouncing packets back on incoming interface.\n"));
00297     goto return_noroute;
00298   }
00299 #endif /* IP_FORWARD_ALLOW_TX_ON_RX_NETIF */
00300 
00301   /* decrement TTL */
00302   IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
00303   /* send ICMP if TTL == 0 */
00304   if (IPH_TTL(iphdr) == 0) {
00305     MIB2_STATS_INC(mib2.ipinhdrerrors);
00306 #if LWIP_ICMP
00307     /* Don't send ICMP messages in response to ICMP messages */
00308     if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
00309       icmp_time_exceeded(p, ICMP_TE_TTL);
00310     }
00311 #endif /* LWIP_ICMP */
00312     return;
00313   }
00314 
00315   /* Incrementally update the IP checksum. */
00316   if (IPH_CHKSUM(iphdr) >= PP_HTONS(0xffffU - 0x100)) {
00317     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1);
00318   } else {
00319     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100));
00320   }
00321 
00322   LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00323     ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
00324     ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
00325 
00326   IP_STATS_INC(ip.fw);
00327   MIB2_STATS_INC(mib2.ipforwdatagrams);
00328   IP_STATS_INC(ip.xmit);
00329 
00330   PERF_STOP("ip4_forward");
00331   /* don't fragment if interface has mtu set to 0 [loopif] */
00332   if (netif->mtu && (p->tot_len > netif->mtu)) {
00333     if ((IPH_OFFSET(iphdr) & PP_NTOHS(IP_DF)) == 0) {
00334 #if IP_FRAG
00335       ip4_frag(p, netif, ip4_current_dest_addr());
00336 #else /* IP_FRAG */
00337       /* @todo: send ICMP Destination Unreachable code 13 "Communication administratively prohibited"? */
00338 #endif /* IP_FRAG */
00339     } else {
00340 #if LWIP_ICMP
00341       /* send ICMP Destination Unreachable code 4: "Fragmentation Needed and DF Set" */
00342       icmp_dest_unreach(p, ICMP_DUR_FRAG);
00343 #endif /* LWIP_ICMP */
00344     }
00345     return;
00346   }
00347   /* transmit pbuf on chosen interface */
00348   netif->output(netif, p, ip4_current_dest_addr());
00349   return;
00350 return_noroute:
00351   MIB2_STATS_INC(mib2.ipoutnoroutes);
00352 }
00353 #endif /* IP_FORWARD */
00354 
00355 /**
00356  * This function is called by the network interface device driver when
00357  * an IP packet is received. The function does the basic checks of the
00358  * IP header such as packet size being at least larger than the header
00359  * size etc. If the packet was not destined for us, the packet is
00360  * forwarded (using ip_forward). The IP checksum is always checked.
00361  *
00362  * Finally, the packet is sent to the upper layer protocol input function.
00363  *
00364  * @param p the received IP packet (p->payload points to IP header)
00365  * @param inp the netif on which this packet was received
00366  * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
00367  *         processed, but currently always returns ERR_OK)
00368  */
00369 err_t
00370 ip4_input(struct pbuf *p, struct netif *inp)
00371 {
00372   struct ip_hdr *iphdr;
00373   struct netif *netif;
00374   u16_t iphdr_hlen;
00375   u16_t iphdr_len;
00376 #if IP_ACCEPT_LINK_LAYER_ADDRESSING || LWIP_IGMP
00377   int check_ip_src = 1;
00378 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING || LWIP_IGMP */
00379 
00380   IP_STATS_INC(ip.recv);
00381   MIB2_STATS_INC(mib2.ipinreceives);
00382 
00383   /* identify the IP header */
00384   iphdr = (struct ip_hdr *)p->payload;
00385   if (IPH_V(iphdr) != 4) {
00386     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_WARNING, ("IP packet dropped due to bad version number %"U16_F"\n", (u16_t)IPH_V(iphdr)));
00387     ip4_debug_print(p);
00388     pbuf_free(p);
00389     IP_STATS_INC(ip.err);
00390     IP_STATS_INC(ip.drop);
00391     MIB2_STATS_INC(mib2.ipinhdrerrors);
00392     return ERR_OK;
00393   }
00394 
00395 #ifdef LWIP_HOOK_IP4_INPUT
00396   if (LWIP_HOOK_IP4_INPUT(p, inp)) {
00397     /* the packet has been eaten */
00398     return ERR_OK;
00399   }
00400 #endif
00401 
00402   /* obtain IP header length in number of 32-bit words */
00403   iphdr_hlen = IPH_HL(iphdr);
00404   /* calculate IP header length in bytes */
00405   iphdr_hlen *= 4;
00406   /* obtain ip length in bytes */
00407   iphdr_len = lwip_ntohs(IPH_LEN(iphdr));
00408 
00409   /* Trim pbuf. This is especially required for packets < 60 bytes. */
00410   if (iphdr_len < p->tot_len) {
00411     pbuf_realloc(p, iphdr_len);
00412   }
00413 
00414   /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
00415   if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len) || (iphdr_hlen < IP_HLEN)) {
00416     if (iphdr_hlen < IP_HLEN) {
00417       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00418         ("ip4_input: short IP header (%"U16_F" bytes) received, IP packet dropped\n", iphdr_hlen));
00419     }
00420     if (iphdr_hlen > p->len) {
00421       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00422         ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
00423         iphdr_hlen, p->len));
00424     }
00425     if (iphdr_len > p->tot_len) {
00426       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00427         ("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), IP packet dropped.\n",
00428         iphdr_len, p->tot_len));
00429     }
00430     /* free (drop) packet pbufs */
00431     pbuf_free(p);
00432     IP_STATS_INC(ip.lenerr);
00433     IP_STATS_INC(ip.drop);
00434     MIB2_STATS_INC(mib2.ipindiscards);
00435     return ERR_OK;
00436   }
00437 
00438   /* verify checksum */
00439 #if CHECKSUM_CHECK_IP
00440   IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_IP) {
00441     if (inet_chksum(iphdr, iphdr_hlen) != 0) {
00442 
00443       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00444         ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
00445       ip4_debug_print(p);
00446       pbuf_free(p);
00447       IP_STATS_INC(ip.chkerr);
00448       IP_STATS_INC(ip.drop);
00449       MIB2_STATS_INC(mib2.ipinhdrerrors);
00450       return ERR_OK;
00451     }
00452   }
00453 #endif
00454 
00455   /* copy IP addresses to aligned ip_addr_t */
00456   ip_addr_copy_from_ip4(ip_data.current_iphdr_dest, iphdr->dest);
00457   ip_addr_copy_from_ip4(ip_data.current_iphdr_src, iphdr->src);
00458 
00459   /* match packet against an interface, i.e. is this packet for us? */
00460   if (ip4_addr_ismulticast(ip4_current_dest_addr())) {
00461 #if LWIP_IGMP
00462     if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, ip4_current_dest_addr()))) {
00463       /* IGMP snooping switches need 0.0.0.0 to be allowed as source address (RFC 4541) */
00464       ip4_addr_t allsystems;
00465       IP4_ADDR(&allsystems, 224, 0, 0, 1);
00466       if (ip4_addr_cmp(ip4_current_dest_addr(), &allsystems) &&
00467           ip4_addr_isany(ip4_current_src_addr())) {
00468         check_ip_src = 0;
00469       }
00470       netif = inp;
00471     } else {
00472       netif = NULL;
00473     }
00474 #else /* LWIP_IGMP */
00475     if ((netif_is_up(inp)) && (!ip4_addr_isany_val(*netif_ip4_addr(inp)))) {
00476       netif = inp;
00477     } else {
00478       netif = NULL;
00479     }
00480 #endif /* LWIP_IGMP */
00481   } else {
00482     /* start trying with inp. if that's not acceptable, start walking the
00483        list of configured netifs.
00484        'first' is used as a boolean to mark whether we started walking the list */
00485     int first = 1;
00486     netif = inp;
00487     do {
00488       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",
00489           ip4_addr_get_u32(&iphdr->dest), ip4_addr_get_u32(netif_ip4_addr(netif)),
00490           ip4_addr_get_u32(&iphdr->dest) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
00491           ip4_addr_get_u32(netif_ip4_addr(netif)) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
00492           ip4_addr_get_u32(&iphdr->dest) & ~ip4_addr_get_u32(netif_ip4_netmask(netif))));
00493 
00494       /* interface is up and configured? */
00495       if ((netif_is_up(netif)) && (!ip4_addr_isany_val(*netif_ip4_addr(netif)))) {
00496         /* unicast to this interface address? */
00497         if (ip4_addr_cmp(ip4_current_dest_addr(), netif_ip4_addr(netif)) ||
00498             /* or broadcast on this interface network address? */
00499             ip4_addr_isbroadcast(ip4_current_dest_addr(), netif)
00500 #if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
00501             || (ip4_addr_get_u32(ip4_current_dest_addr()) == PP_HTONL(IPADDR_LOOPBACK))
00502 #endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
00503             ) {
00504           LWIP_DEBUGF(IP_DEBUG, ("ip4_input: packet accepted on interface %c%c\n",
00505               netif->name[0], netif->name[1]));
00506           /* break out of for loop */
00507           break;
00508         }
00509 #if LWIP_AUTOIP
00510         /* connections to link-local addresses must persist after changing
00511            the netif's address (RFC3927 ch. 1.9) */
00512         if (autoip_accept_packet(netif, ip4_current_dest_addr())) {
00513           LWIP_DEBUGF(IP_DEBUG, ("ip4_input: LLA packet accepted on interface %c%c\n",
00514               netif->name[0], netif->name[1]));
00515           /* break out of for loop */
00516           break;
00517         }
00518 #endif /* LWIP_AUTOIP */
00519       }
00520       if (first) {
00521 #if !LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF
00522         /* Packets sent to the loopback address must not be accepted on an
00523          * interface that does not have the loopback address assigned to it,
00524          * unless a non-loopback interface is used for loopback traffic. */
00525         if (ip4_addr_isloopback(ip4_current_dest_addr())) {
00526           netif = NULL;
00527           break;
00528         }
00529 #endif /* !LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF */
00530         first = 0;
00531         netif = netif_list;
00532       } else {
00533         netif = netif->next;
00534       }
00535       if (netif == inp) {
00536         netif = netif->next;
00537       }
00538     } while (netif != NULL);
00539   }
00540 
00541 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00542   /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
00543    * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
00544    * According to RFC 1542 section 3.1.1, referred by RFC 2131).
00545    *
00546    * If you want to accept private broadcast communication while a netif is down,
00547    * define LWIP_IP_ACCEPT_UDP_PORT(dst_port), e.g.:
00548    *
00549    * #define LWIP_IP_ACCEPT_UDP_PORT(dst_port) ((dst_port) == PP_NTOHS(12345))
00550    */
00551   if (netif == NULL) {
00552     /* remote port is DHCP server? */
00553     if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
00554       struct udp_hdr *udphdr = (struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen);
00555       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: UDP packet to DHCP client port %"U16_F"\n",
00556         lwip_ntohs(udphdr->dest)));
00557       if (IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(udphdr->dest)) {
00558         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: DHCP packet accepted.\n"));
00559         netif = inp;
00560         check_ip_src = 0;
00561       }
00562     }
00563   }
00564 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00565 
00566   /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
00567 #if LWIP_IGMP || IP_ACCEPT_LINK_LAYER_ADDRESSING
00568   if (check_ip_src
00569 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00570   /* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
00571       && !ip4_addr_isany_val(*ip4_current_src_addr())
00572 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00573      )
00574 #endif /* LWIP_IGMP || IP_ACCEPT_LINK_LAYER_ADDRESSING */
00575   {
00576     if ((ip4_addr_isbroadcast(ip4_current_src_addr(), inp)) ||
00577         (ip4_addr_ismulticast(ip4_current_src_addr()))) {
00578       /* packet source is not valid */
00579       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("ip4_input: packet source is not valid.\n"));
00580       /* free (drop) packet pbufs */
00581       pbuf_free(p);
00582       IP_STATS_INC(ip.drop);
00583       MIB2_STATS_INC(mib2.ipinaddrerrors);
00584       MIB2_STATS_INC(mib2.ipindiscards);
00585       return ERR_OK;
00586     }
00587   }
00588 
00589   /* packet not for us? */
00590   if (netif == NULL) {
00591     /* packet not for us, route or discard */
00592     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: packet not for us.\n"));
00593 #if IP_FORWARD
00594     /* non-broadcast packet? */
00595     if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), inp)) {
00596       /* try to forward IP packet on (other) interfaces */
00597       ip4_forward(p, iphdr, inp);
00598     } else
00599 #endif /* IP_FORWARD */
00600     {
00601       IP_STATS_INC(ip.drop);
00602       MIB2_STATS_INC(mib2.ipinaddrerrors);
00603       MIB2_STATS_INC(mib2.ipindiscards);
00604     }
00605     pbuf_free(p);
00606     return ERR_OK;
00607   }
00608   /* packet consists of multiple fragments? */
00609   if ((IPH_OFFSET(iphdr) & PP_HTONS(IP_OFFMASK | IP_MF)) != 0) {
00610 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
00611     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 ip4_reass()\n",
00612       lwip_ntohs(IPH_ID(iphdr)), p->tot_len, lwip_ntohs(IPH_LEN(iphdr)), (u16_t)!!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (u16_t)((lwip_ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8)));
00613     /* reassemble the packet*/
00614     p = ip4_reass(p);
00615     /* packet not fully reassembled yet? */
00616     if (p == NULL) {
00617       return ERR_OK;
00618     }
00619     iphdr = (struct ip_hdr *)p->payload;
00620 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
00621     pbuf_free(p);
00622     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
00623       lwip_ntohs(IPH_OFFSET(iphdr))));
00624     IP_STATS_INC(ip.opterr);
00625     IP_STATS_INC(ip.drop);
00626     /* unsupported protocol feature */
00627     MIB2_STATS_INC(mib2.ipinunknownprotos);
00628     return ERR_OK;
00629 #endif /* IP_REASSEMBLY */
00630   }
00631 
00632 #if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
00633 
00634 #if LWIP_IGMP
00635   /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
00636   if ((iphdr_hlen > IP_HLEN) &&  (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
00637 #else
00638   if (iphdr_hlen > IP_HLEN) {
00639 #endif /* LWIP_IGMP */
00640     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
00641     pbuf_free(p);
00642     IP_STATS_INC(ip.opterr);
00643     IP_STATS_INC(ip.drop);
00644     /* unsupported protocol feature */
00645     MIB2_STATS_INC(mib2.ipinunknownprotos);
00646     return ERR_OK;
00647   }
00648 #endif /* IP_OPTIONS_ALLOWED == 0 */
00649 
00650   /* send to upper layers */
00651   LWIP_DEBUGF(IP_DEBUG, ("ip4_input: \n"));
00652   ip4_debug_print(p);
00653   LWIP_DEBUGF(IP_DEBUG, ("ip4_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
00654 
00655   ip_data.current_netif = netif;
00656   ip_data.current_input_netif = inp;
00657   ip_data.current_ip4_header = iphdr;
00658   ip_data.current_ip_header_tot_len = IPH_HL(iphdr) * 4;
00659 
00660 #if LWIP_RAW
00661   /* raw input did not eat the packet? */
00662   if (raw_input(p, inp) == 0)
00663 #endif /* LWIP_RAW */
00664   {
00665     pbuf_header(p, -(s16_t)iphdr_hlen); /* Move to payload, no check necessary. */
00666 
00667     switch (IPH_PROTO(iphdr)) {
00668 #if LWIP_UDP
00669     case IP_PROTO_UDP:
00670 #if LWIP_UDPLITE
00671     case IP_PROTO_UDPLITE:
00672 #endif /* LWIP_UDPLITE */
00673       MIB2_STATS_INC(mib2.ipindelivers);
00674       udp_input(p, inp);
00675       break;
00676 #endif /* LWIP_UDP */
00677 #if LWIP_TCP
00678     case IP_PROTO_TCP:
00679       MIB2_STATS_INC(mib2.ipindelivers);
00680       tcp_input(p, inp);
00681       break;
00682 #endif /* LWIP_TCP */
00683 #if LWIP_ICMP
00684     case IP_PROTO_ICMP:
00685       MIB2_STATS_INC(mib2.ipindelivers);
00686       icmp_input(p, inp);
00687       break;
00688 #endif /* LWIP_ICMP */
00689 #if LWIP_IGMP
00690     case IP_PROTO_IGMP:
00691       igmp_input(p, inp, ip4_current_dest_addr());
00692       break;
00693 #endif /* LWIP_IGMP */
00694     default:
00695 #if LWIP_ICMP
00696       /* send ICMP destination protocol unreachable unless is was a broadcast */
00697       if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), netif) &&
00698           !ip4_addr_ismulticast(ip4_current_dest_addr())) {
00699         pbuf_header_force(p, iphdr_hlen); /* Move to ip header, no check necessary. */
00700         p->payload = iphdr;
00701         icmp_dest_unreach(p, ICMP_DUR_PROTO);
00702       }
00703 #endif /* LWIP_ICMP */
00704       pbuf_free(p);
00705 
00706       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Unsupported transport protocol %"U16_F"\n", (u16_t)IPH_PROTO(iphdr)));
00707 
00708       IP_STATS_INC(ip.proterr);
00709       IP_STATS_INC(ip.drop);
00710       MIB2_STATS_INC(mib2.ipinunknownprotos);
00711     }
00712   }
00713 
00714   /* @todo: this is not really necessary... */
00715   ip_data.current_netif = NULL;
00716   ip_data.current_input_netif = NULL;
00717   ip_data.current_ip4_header = NULL;
00718   ip_data.current_ip_header_tot_len = 0;
00719   ip4_addr_set_any(ip4_current_src_addr());
00720   ip4_addr_set_any(ip4_current_dest_addr());
00721 
00722   return ERR_OK;
00723 }
00724 
00725 /**
00726  * Sends an IP packet on a network interface. This function constructs
00727  * the IP header and calculates the IP header checksum. If the source
00728  * IP address is NULL, the IP address of the outgoing network
00729  * interface is filled in as source address.
00730  * If the destination IP address is LWIP_IP_HDRINCL, p is assumed to already
00731  * include an IP header and p->payload points to it instead of the data.
00732  *
00733  * @param p the packet to send (p->payload points to the data, e.g. next
00734             protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
00735             IP header and p->payload points to that IP header)
00736  * @param src the source IP address to send from (if src == IP4_ADDR_ANY, the
00737  *         IP  address of the netif used to send is used as source address)
00738  * @param dest the destination IP address to send the packet to
00739  * @param ttl the TTL value to be set in the IP header
00740  * @param tos the TOS value to be set in the IP header
00741  * @param proto the PROTOCOL to be set in the IP header
00742  * @param netif the netif on which to send this packet
00743  * @return ERR_OK if the packet was sent OK
00744  *         ERR_BUF if p doesn't have enough space for IP/LINK headers
00745  *         returns errors returned by netif->output
00746  *
00747  * @note ip_id: RFC791 "some host may be able to simply use
00748  *  unique identifiers independent of destination"
00749  */
00750 err_t
00751 ip4_output_if(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00752              u8_t ttl, u8_t tos,
00753              u8_t proto, struct netif *netif)
00754 {
00755 #if IP_OPTIONS_SEND
00756   return ip4_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
00757 }
00758 
00759 /**
00760  * Same as ip_output_if() but with the possibility to include IP options:
00761  *
00762  * @ param ip_options pointer to the IP options, copied into the IP header
00763  * @ param optlen length of ip_options
00764  */
00765 err_t
00766 ip4_output_if_opt(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00767        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
00768        u16_t optlen)
00769 {
00770 #endif /* IP_OPTIONS_SEND */
00771   const ip4_addr_t *src_used = src;
00772   if (dest != LWIP_IP_HDRINCL) {
00773     if (ip4_addr_isany(src)) {
00774       src_used = netif_ip4_addr(netif);
00775     }
00776   }
00777 
00778 #if IP_OPTIONS_SEND
00779   return ip4_output_if_opt_src(p, src_used, dest, ttl, tos, proto, netif,
00780     ip_options, optlen);
00781 #else /* IP_OPTIONS_SEND */
00782   return ip4_output_if_src(p, src_used, dest, ttl, tos, proto, netif);
00783 #endif /* IP_OPTIONS_SEND */
00784 }
00785 
00786 /**
00787  * Same as ip_output_if() but 'src' address is not replaced by netif address
00788  * when it is 'any'.
00789  */
00790 err_t
00791 ip4_output_if_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00792              u8_t ttl, u8_t tos,
00793              u8_t proto, struct netif *netif)
00794 {
00795 #if IP_OPTIONS_SEND
00796   return ip4_output_if_opt_src(p, src, dest, ttl, tos, proto, netif, NULL, 0);
00797 }
00798 
00799 /**
00800  * Same as ip_output_if_opt() but 'src' address is not replaced by netif address
00801  * when it is 'any'.
00802  */
00803 err_t
00804 ip4_output_if_opt_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00805        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
00806        u16_t optlen)
00807 {
00808 #endif /* IP_OPTIONS_SEND */
00809   struct ip_hdr *iphdr;
00810   ip4_addr_t dest_addr;
00811 #if CHECKSUM_GEN_IP_INLINE
00812   u32_t chk_sum = 0;
00813 #endif /* CHECKSUM_GEN_IP_INLINE */
00814 
00815   LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
00816 
00817   MIB2_STATS_INC(mib2.ipoutrequests);
00818 
00819   /* Should the IP header be generated or is it already included in p? */
00820   if (dest != LWIP_IP_HDRINCL) {
00821     u16_t ip_hlen = IP_HLEN;
00822 #if IP_OPTIONS_SEND
00823     u16_t optlen_aligned = 0;
00824     if (optlen != 0) {
00825 #if CHECKSUM_GEN_IP_INLINE
00826       int i;
00827 #endif /* CHECKSUM_GEN_IP_INLINE */
00828       /* round up to a multiple of 4 */
00829       optlen_aligned = ((optlen + 3) & ~3);
00830       ip_hlen += optlen_aligned;
00831       /* First write in the IP options */
00832       if (pbuf_header(p, optlen_aligned)) {
00833         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output_if_opt: not enough room for IP options in pbuf\n"));
00834         IP_STATS_INC(ip.err);
00835         MIB2_STATS_INC(mib2.ipoutdiscards);
00836         return ERR_BUF;
00837       }
00838       MEMCPY(p->payload, ip_options, optlen);
00839       if (optlen < optlen_aligned) {
00840         /* zero the remaining bytes */
00841         memset(((char*)p->payload) + optlen, 0, optlen_aligned - optlen);
00842       }
00843 #if CHECKSUM_GEN_IP_INLINE
00844       for (i = 0; i < optlen_aligned/2; i++) {
00845         chk_sum += ((u16_t*)p->payload)[i];
00846       }
00847 #endif /* CHECKSUM_GEN_IP_INLINE */
00848     }
00849 #endif /* IP_OPTIONS_SEND */
00850     /* generate IP header */
00851     if (pbuf_header(p, IP_HLEN)) {
00852       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output: not enough room for IP header in pbuf\n"));
00853 
00854       IP_STATS_INC(ip.err);
00855       MIB2_STATS_INC(mib2.ipoutdiscards);
00856       return ERR_BUF;
00857     }
00858 
00859     iphdr = (struct ip_hdr *)p->payload;
00860     LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
00861                (p->len >= sizeof(struct ip_hdr)));
00862 
00863     IPH_TTL_SET(iphdr, ttl);
00864     IPH_PROTO_SET(iphdr, proto);
00865 #if CHECKSUM_GEN_IP_INLINE
00866     chk_sum += PP_NTOHS(proto | (ttl << 8));
00867 #endif /* CHECKSUM_GEN_IP_INLINE */
00868 
00869     /* dest cannot be NULL here */
00870     ip4_addr_copy(iphdr->dest, *dest);
00871 #if CHECKSUM_GEN_IP_INLINE
00872     chk_sum += ip4_addr_get_u32(&iphdr->dest) & 0xFFFF;
00873     chk_sum += ip4_addr_get_u32(&iphdr->dest) >> 16;
00874 #endif /* CHECKSUM_GEN_IP_INLINE */
00875 
00876     IPH_VHL_SET(iphdr, 4, ip_hlen / 4);
00877     IPH_TOS_SET(iphdr, tos);
00878 #if CHECKSUM_GEN_IP_INLINE
00879     chk_sum += PP_NTOHS(tos | (iphdr->_v_hl << 8));
00880 #endif /* CHECKSUM_GEN_IP_INLINE */
00881     IPH_LEN_SET(iphdr, lwip_htons(p->tot_len));
00882 #if CHECKSUM_GEN_IP_INLINE
00883     chk_sum += iphdr->_len;
00884 #endif /* CHECKSUM_GEN_IP_INLINE */
00885     IPH_OFFSET_SET(iphdr, 0);
00886     IPH_ID_SET(iphdr, lwip_htons(ip_id));
00887 #if CHECKSUM_GEN_IP_INLINE
00888     chk_sum += iphdr->_id;
00889 #endif /* CHECKSUM_GEN_IP_INLINE */
00890     ++ip_id;
00891 
00892     if (src == NULL) {
00893       ip4_addr_copy(iphdr->src, *IP4_ADDR_ANY4);
00894     } else {
00895       /* src cannot be NULL here */
00896       ip4_addr_copy(iphdr->src, *src);
00897     }
00898 
00899 #if CHECKSUM_GEN_IP_INLINE
00900     chk_sum += ip4_addr_get_u32(&iphdr->src) & 0xFFFF;
00901     chk_sum += ip4_addr_get_u32(&iphdr->src) >> 16;
00902     chk_sum = (chk_sum >> 16) + (chk_sum & 0xFFFF);
00903     chk_sum = (chk_sum >> 16) + chk_sum;
00904     chk_sum = ~chk_sum;
00905     IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
00906       iphdr->_chksum = (u16_t)chk_sum; /* network order */
00907     }
00908 #if LWIP_CHECKSUM_CTRL_PER_NETIF
00909     else {
00910       IPH_CHKSUM_SET(iphdr, 0);
00911     }
00912 #endif /* LWIP_CHECKSUM_CTRL_PER_NETIF*/
00913 #else /* CHECKSUM_GEN_IP_INLINE */
00914     IPH_CHKSUM_SET(iphdr, 0);
00915 #if CHECKSUM_GEN_IP
00916     IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
00917       IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
00918     }
00919 #endif /* CHECKSUM_GEN_IP */
00920 #endif /* CHECKSUM_GEN_IP_INLINE */
00921   } else {
00922     /* IP header already included in p */
00923     iphdr = (struct ip_hdr *)p->payload;
00924     ip4_addr_copy(dest_addr, iphdr->dest);
00925     dest = &dest_addr;
00926   }
00927 
00928   IP_STATS_INC(ip.xmit);
00929 
00930   LWIP_DEBUGF(IP_DEBUG, ("ip4_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], (u16_t)netif->num));
00931   ip4_debug_print(p);
00932 
00933 #if ENABLE_LOOPBACK
00934   if (ip4_addr_cmp(dest, netif_ip4_addr(netif))
00935 #if !LWIP_HAVE_LOOPIF
00936       || ip4_addr_isloopback(dest)
00937 #endif /* !LWIP_HAVE_LOOPIF */
00938       ) {
00939     /* Packet to self, enqueue it for loopback */
00940     LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
00941     return netif_loop_output(netif, p);
00942   }
00943 #if LWIP_MULTICAST_TX_OPTIONS
00944   if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
00945     netif_loop_output(netif, p);
00946   }
00947 #endif /* LWIP_MULTICAST_TX_OPTIONS */
00948 #endif /* ENABLE_LOOPBACK */
00949 #if IP_FRAG
00950   /* don't fragment if interface has mtu set to 0 [loopif] */
00951   if (netif->mtu && (p->tot_len > netif->mtu)) {
00952     return ip4_frag(p, netif, dest);
00953   }
00954 #endif /* IP_FRAG */
00955 
00956   LWIP_DEBUGF(IP_DEBUG, ("ip4_output_if: call netif->output()\n"));
00957   return netif->output(netif, p, dest);
00958 }
00959 
00960 /**
00961  * Simple interface to ip_output_if. It finds the outgoing network
00962  * interface and calls upon ip_output_if to do the actual work.
00963  *
00964  * @param p the packet to send (p->payload points to the data, e.g. next
00965             protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
00966             IP header and p->payload points to that IP header)
00967  * @param src the source IP address to send from (if src == IP4_ADDR_ANY, the
00968  *         IP  address of the netif used to send is used as source address)
00969  * @param dest the destination IP address to send the packet to
00970  * @param ttl the TTL value to be set in the IP header
00971  * @param tos the TOS value to be set in the IP header
00972  * @param proto the PROTOCOL to be set in the IP header
00973  *
00974  * @return ERR_RTE if no route is found
00975  *         see ip_output_if() for more return values
00976  */
00977 err_t
00978 ip4_output(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00979           u8_t ttl, u8_t tos, u8_t proto)
00980 {
00981   struct netif *netif;
00982 
00983   LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
00984 
00985   if ((netif = ip4_route_src(dest, src)) == NULL) {
00986     LWIP_DEBUGF(IP_DEBUG, ("ip4_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00987       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00988     IP_STATS_INC(ip.rterr);
00989     return ERR_RTE;
00990   }
00991 
00992   return ip4_output_if(p, src, dest, ttl, tos, proto, netif);
00993 }
00994 
00995 #if LWIP_NETIF_HWADDRHINT
00996 /** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
00997  *  before calling ip_output_if.
00998  *
00999  * @param p the packet to send (p->payload points to the data, e.g. next
01000             protocol header; if dest == LWIP_IP_HDRINCL, p already includes an
01001             IP header and p->payload points to that IP header)
01002  * @param src the source IP address to send from (if src == IP4_ADDR_ANY, the
01003  *         IP  address of the netif used to send is used as source address)
01004  * @param dest the destination IP address to send the packet to
01005  * @param ttl the TTL value to be set in the IP header
01006  * @param tos the TOS value to be set in the IP header
01007  * @param proto the PROTOCOL to be set in the IP header
01008  * @param addr_hint address hint pointer set to netif->addr_hint before
01009  *        calling ip_output_if()
01010  *
01011  * @return ERR_RTE if no route is found
01012  *         see ip_output_if() for more return values
01013  */
01014 err_t
01015 ip4_output_hinted(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
01016           u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
01017 {
01018   struct netif *netif;
01019   err_t err;
01020 
01021   LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
01022 
01023   if ((netif = ip4_route_src(dest, src)) == NULL) {
01024     LWIP_DEBUGF(IP_DEBUG, ("ip4_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
01025       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
01026     IP_STATS_INC(ip.rterr);
01027     return ERR_RTE;
01028   }
01029 
01030   NETIF_SET_HWADDRHINT(netif, addr_hint);
01031   err = ip4_output_if(p, src, dest, ttl, tos, proto, netif);
01032   NETIF_SET_HWADDRHINT(netif, NULL);
01033 
01034   return err;
01035 }
01036 #endif /* LWIP_NETIF_HWADDRHINT*/
01037 
01038 #if IP_DEBUG
01039 /* Print an IP header by using LWIP_DEBUGF
01040  * @param p an IP packet, p->payload pointing to the IP header
01041  */
01042 void
01043 ip4_debug_print(struct pbuf *p)
01044 {
01045   struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
01046 
01047   LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
01048   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01049   LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" |  0x%02"X16_F" |     %5"U16_F"     | (v, hl, tos, len)\n",
01050                     (u16_t)IPH_V(iphdr),
01051                     (u16_t)IPH_HL(iphdr),
01052                     (u16_t)IPH_TOS(iphdr),
01053                     lwip_ntohs(IPH_LEN(iphdr))));
01054   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01055   LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      |%"U16_F"%"U16_F"%"U16_F"|    %4"U16_F"   | (id, flags, offset)\n",
01056                     lwip_ntohs(IPH_ID(iphdr)),
01057                     (u16_t)(lwip_ntohs(IPH_OFFSET(iphdr)) >> 15 & 1),
01058                     (u16_t)(lwip_ntohs(IPH_OFFSET(iphdr)) >> 14 & 1),
01059                     (u16_t)(lwip_ntohs(IPH_OFFSET(iphdr)) >> 13 & 1),
01060                     (u16_t)(lwip_ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)));
01061   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01062   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |    0x%04"X16_F"     | (ttl, proto, chksum)\n",
01063                     (u16_t)IPH_TTL(iphdr),
01064                     (u16_t)IPH_PROTO(iphdr),
01065                     lwip_ntohs(IPH_CHKSUM(iphdr))));
01066   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01067   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (src)\n",
01068                     ip4_addr1_16(&iphdr->src),
01069                     ip4_addr2_16(&iphdr->src),
01070                     ip4_addr3_16(&iphdr->src),
01071                     ip4_addr4_16(&iphdr->src)));
01072   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01073   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (dest)\n",
01074                     ip4_addr1_16(&iphdr->dest),
01075                     ip4_addr2_16(&iphdr->dest),
01076                     ip4_addr3_16(&iphdr->dest),
01077                     ip4_addr4_16(&iphdr->dest)));
01078   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01079 }
01080 #endif /* IP_DEBUG */
01081 
01082 #endif /* LWIP_IPV4 */