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/dhcp.h"
00057 #include "lwip/autoip.h"
00058 #include "lwip/stats.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 /** Set a default netif for IPv4 multicast. */
00110 void
00111 ip4_set_default_multicast_netif(struct netif* default_multicast_netif)
00112 {
00113   ip4_default_multicast_netif = default_multicast_netif;
00114 }
00115 #endif /* LWIP_MULTICAST_TX_OPTIONS */
00116 
00117 #ifdef LWIP_HOOK_IP4_ROUTE_SRC
00118 /**
00119  * Source based IPv4 routing must be fully implemented in
00120  * LWIP_HOOK_IP4_ROUTE_SRC(). This function only provides he parameters.
00121  */
00122 struct netif *
00123 ip4_route_src(const ip4_addr_t *dest, const ip4_addr_t *src)
00124 {
00125   if (src != NULL) {
00126     /* when src==NULL, the hook is called from ip4_route(dest) */
00127     struct netif *netif = LWIP_HOOK_IP4_ROUTE_SRC(dest, src);
00128     if (netif != NULL) {
00129       return netif;
00130     }
00131   }
00132   return ip4_route(dest);
00133 }
00134 #endif /* LWIP_HOOK_IP4_ROUTE_SRC */
00135 
00136 /**
00137  * Finds the appropriate network interface for a given IP address. It
00138  * searches the list of network interfaces linearly. A match is found
00139  * if the masked IP address of the network interface equals the masked
00140  * IP address given to the function.
00141  *
00142  * @param dest the destination IP address for which to find the route
00143  * @return the netif on which to send to reach dest
00144  */
00145 struct netif *
00146 ip4_route(const ip4_addr_t *dest)
00147 {
00148   struct netif *netif;
00149 
00150 #if LWIP_MULTICAST_TX_OPTIONS
00151   /* Use administratively selected interface for multicast by default */
00152   if (ip4_addr_ismulticast(dest) && ip4_default_multicast_netif) {
00153     return ip4_default_multicast_netif;
00154   }
00155 #endif /* LWIP_MULTICAST_TX_OPTIONS */
00156 
00157   /* iterate through netifs */
00158   for (netif = netif_list; netif != NULL; netif = netif->next) {
00159     /* is the netif up, does it have a link and a valid address? */
00160     if (netif_is_up(netif) && netif_is_link_up(netif) && !ip4_addr_isany_val(*netif_ip4_addr(netif))) {
00161       /* network mask matches? */
00162       if (ip4_addr_netcmp(dest, netif_ip4_addr(netif), netif_ip4_netmask(netif))) {
00163         /* return netif on which to forward IP packet */
00164         return netif;
00165       }
00166       /* gateway matches on a non broadcast interface? (i.e. peer in a point to point interface) */
00167       if (((netif->flags & NETIF_FLAG_BROADCAST) == 0) && ip4_addr_cmp(dest, netif_ip4_gw(netif))) {
00168         /* return netif on which to forward IP packet */
00169         return netif;
00170       }
00171     }
00172   }
00173 
00174 #if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
00175   /* loopif is disabled, looopback traffic is passed through any netif */
00176   if (ip4_addr_isloopback(dest)) {
00177     /* don't check for link on loopback traffic */
00178     if (netif_is_up(netif_default)) {
00179       return netif_default;
00180     }
00181     /* default netif is not up, just use any netif for loopback traffic */
00182     for (netif = netif_list; netif != NULL; netif = netif->next) {
00183       if (netif_is_up(netif)) {
00184         return netif;
00185       }
00186     }
00187     return NULL;
00188   }
00189 #endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
00190 
00191 #ifdef LWIP_HOOK_IP4_ROUTE_SRC
00192   netif = LWIP_HOOK_IP4_ROUTE_SRC(dest, NULL);
00193   if (netif != NULL) {
00194     return netif;
00195   }
00196 #elif defined(LWIP_HOOK_IP4_ROUTE)
00197   netif = LWIP_HOOK_IP4_ROUTE(dest);
00198   if (netif != NULL) {
00199     return netif;
00200   }
00201 #endif
00202 
00203   if ((netif_default == NULL) || !netif_is_up(netif_default) || !netif_is_link_up(netif_default) ||
00204       ip4_addr_isany_val(*netif_ip4_addr(netif_default))) {
00205     /* No matching netif found and default netif is not usable.
00206        If this is not good enough for you, use LWIP_HOOK_IP4_ROUTE() */
00207     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_route: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00208       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00209     IP_STATS_INC(ip.rterr);
00210     MIB2_STATS_INC(mib2.ipoutnoroutes);
00211     return NULL;
00212   }
00213 
00214   return netif_default;
00215 }
00216 
00217 #if IP_FORWARD
00218 /**
00219  * Determine whether an IP address is in a reserved set of addresses
00220  * that may not be forwarded, or whether datagrams to that destination
00221  * may be forwarded.
00222  * @param p the packet to forward
00223  * @param dest the destination IP address
00224  * @return 1: can forward 0: discard
00225  */
00226 static int
00227 ip4_canforward(struct pbuf *p)
00228 {
00229   u32_t addr = htonl(ip4_addr_get_u32(ip4_current_dest_addr()));
00230 
00231   if (p->flags & PBUF_FLAG_LLBCAST) {
00232     /* don't route link-layer broadcasts */
00233     return 0;
00234   }
00235   if ((p->flags & PBUF_FLAG_LLMCAST) && !IP_MULTICAST(addr)) {
00236     /* don't route link-layer multicasts unless the destination address is an IP
00237        multicast address */
00238     return 0;
00239   }
00240   if (IP_EXPERIMENTAL(addr)) {
00241     return 0;
00242   }
00243   if (IP_CLASSA(addr)) {
00244     u32_t net = addr & IP_CLASSA_NET;
00245     if ((net == 0) || (net == ((u32_t)IP_LOOPBACKNET << IP_CLASSA_NSHIFT))) {
00246       /* don't route loopback packets */
00247       return 0;
00248     }
00249   }
00250   return 1;
00251 }
00252 
00253 /**
00254  * Forwards an IP packet. It finds an appropriate route for the
00255  * packet, decrements the TTL value of the packet, adjusts the
00256  * checksum and outputs the packet on the appropriate interface.
00257  *
00258  * @param p the packet to forward (p->payload points to IP header)
00259  * @param iphdr the IP header of the input packet
00260  * @param inp the netif on which this packet was received
00261  */
00262 static void
00263 ip4_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
00264 {
00265   struct netif *netif;
00266 
00267   PERF_START;
00268 
00269   if (!ip4_canforward(p)) {
00270     goto return_noroute;
00271   }
00272 
00273   /* RFC3927 2.7: do not forward link-local addresses */
00274   if (ip4_addr_islinklocal(ip4_current_dest_addr())) {
00275     LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: not forwarding LLA %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00276       ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
00277       ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
00278     goto return_noroute;
00279   }
00280 
00281   /* Find network interface where to forward this IP packet to. */
00282   netif = ip4_route_src(ip4_current_dest_addr(), ip4_current_src_addr());
00283   if (netif == NULL) {
00284     LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: no forwarding route for %"U16_F".%"U16_F".%"U16_F".%"U16_F" found\n",
00285       ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
00286       ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
00287     /* @todo: send ICMP_DUR_NET? */
00288     goto return_noroute;
00289   }
00290 #if !IP_FORWARD_ALLOW_TX_ON_RX_NETIF
00291   /* Do not forward packets onto the same network interface on which
00292    * they arrived. */
00293   if (netif == inp) {
00294     LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: not bouncing packets back on incoming interface.\n"));
00295     goto return_noroute;
00296   }
00297 #endif /* IP_FORWARD_ALLOW_TX_ON_RX_NETIF */
00298 
00299   /* decrement TTL */
00300   IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
00301   /* send ICMP if TTL == 0 */
00302   if (IPH_TTL(iphdr) == 0) {
00303     MIB2_STATS_INC(mib2.ipinhdrerrors);
00304 #if LWIP_ICMP
00305     /* Don't send ICMP messages in response to ICMP messages */
00306     if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
00307       icmp_time_exceeded(p, ICMP_TE_TTL);
00308     }
00309 #endif /* LWIP_ICMP */
00310     return;
00311   }
00312 
00313   /* Incrementally update the IP checksum. */
00314   if (IPH_CHKSUM(iphdr) >= PP_HTONS(0xffffU - 0x100)) {
00315     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100) + 1);
00316   } else {
00317     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + PP_HTONS(0x100));
00318   }
00319 
00320   LWIP_DEBUGF(IP_DEBUG, ("ip4_forward: forwarding packet to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00321     ip4_addr1_16(ip4_current_dest_addr()), ip4_addr2_16(ip4_current_dest_addr()),
00322     ip4_addr3_16(ip4_current_dest_addr()), ip4_addr4_16(ip4_current_dest_addr())));
00323 
00324   IP_STATS_INC(ip.fw);
00325   MIB2_STATS_INC(mib2.ipforwdatagrams);
00326   IP_STATS_INC(ip.xmit);
00327 
00328   PERF_STOP("ip4_forward");
00329   /* don't fragment if interface has mtu set to 0 [loopif] */
00330   if (netif->mtu && (p->tot_len > netif->mtu)) {
00331     if ((IPH_OFFSET(iphdr) & PP_NTOHS(IP_DF)) == 0) {
00332 #if IP_FRAG
00333       ip4_frag(p, netif, ip4_current_dest_addr());
00334 #else /* IP_FRAG */
00335       /* @todo: send ICMP Destination Unreachable code 13 "Communication administratively prohibited"? */
00336 #endif /* IP_FRAG */
00337     } else {
00338 #if LWIP_ICMP
00339       /* send ICMP Destination Unreachable code 4: "Fragmentation Needed and DF Set" */
00340       icmp_dest_unreach(p, ICMP_DUR_FRAG);
00341 #endif /* LWIP_ICMP */
00342     }
00343     return;
00344   }
00345   /* transmit pbuf on chosen interface */
00346   netif->output(netif, p, ip4_current_dest_addr());
00347   return;
00348 return_noroute:
00349   MIB2_STATS_INC(mib2.ipoutnoroutes);
00350 }
00351 #endif /* IP_FORWARD */
00352 
00353 /**
00354  * This function is called by the network interface device driver when
00355  * an IP packet is received. The function does the basic checks of the
00356  * IP header such as packet size being at least larger than the header
00357  * size etc. If the packet was not destined for us, the packet is
00358  * forwarded (using ip_forward). The IP checksum is always checked.
00359  *
00360  * Finally, the packet is sent to the upper layer protocol input function.
00361  *
00362  * @param p the received IP packet (p->payload points to IP header)
00363  * @param inp the netif on which this packet was received
00364  * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
00365  *         processed, but currently always returns ERR_OK)
00366  */
00367 err_t
00368 ip4_input(struct pbuf *p, struct netif *inp)
00369 {
00370   struct ip_hdr *iphdr;
00371   struct netif *netif;
00372   u16_t iphdr_hlen;
00373   u16_t iphdr_len;
00374 #if IP_ACCEPT_LINK_LAYER_ADDRESSING || LWIP_IGMP
00375   int check_ip_src = 1;
00376 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING || LWIP_IGMP */
00377 
00378   IP_STATS_INC(ip.recv);
00379   MIB2_STATS_INC(mib2.ipinreceives);
00380 
00381   /* identify the IP header */
00382   iphdr = (struct ip_hdr *)p->payload;
00383   if (IPH_V(iphdr) != 4) {
00384     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_WARNING, ("IP packet dropped due to bad version number %"U16_F"\n", (u16_t)IPH_V(iphdr)));
00385     ip4_debug_print(p);
00386     pbuf_free(p);
00387     IP_STATS_INC(ip.err);
00388     IP_STATS_INC(ip.drop);
00389     MIB2_STATS_INC(mib2.ipinhdrerrors);
00390     return ERR_OK;
00391   }
00392 
00393 #ifdef LWIP_HOOK_IP4_INPUT
00394   if (LWIP_HOOK_IP4_INPUT(p, inp)) {
00395     /* the packet has been eaten */
00396     return ERR_OK;
00397   }
00398 #endif
00399 
00400   /* obtain IP header length in number of 32-bit words */
00401   iphdr_hlen = IPH_HL(iphdr);
00402   /* calculate IP header length in bytes */
00403   iphdr_hlen *= 4;
00404   /* obtain ip length in bytes */
00405   iphdr_len = ntohs(IPH_LEN(iphdr));
00406 
00407   /* Trim pbuf. This is especially required for packets < 60 bytes. */
00408   if (iphdr_len < p->tot_len) {
00409     pbuf_realloc(p, iphdr_len);
00410   }
00411 
00412   /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
00413   if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len) || (iphdr_hlen < IP_HLEN)) {
00414     if (iphdr_hlen < IP_HLEN) {
00415       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00416         ("ip4_input: short IP header (%"U16_F" bytes) received, IP packet dropped\n", iphdr_hlen));
00417     }
00418     if (iphdr_hlen > p->len) {
00419       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00420         ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
00421         iphdr_hlen, p->len));
00422     }
00423     if (iphdr_len > p->tot_len) {
00424       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00425         ("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), IP packet dropped.\n",
00426         iphdr_len, p->tot_len));
00427     }
00428     /* free (drop) packet pbufs */
00429     pbuf_free(p);
00430     IP_STATS_INC(ip.lenerr);
00431     IP_STATS_INC(ip.drop);
00432     MIB2_STATS_INC(mib2.ipindiscards);
00433     return ERR_OK;
00434   }
00435 
00436   /* verify checksum */
00437 #if CHECKSUM_CHECK_IP
00438   IF__NETIF_CHECKSUM_ENABLED(inp, NETIF_CHECKSUM_CHECK_IP) {
00439     if (inet_chksum(iphdr, iphdr_hlen) != 0) {
00440 
00441       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00442         ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
00443       ip4_debug_print(p);
00444       pbuf_free(p);
00445       IP_STATS_INC(ip.chkerr);
00446       IP_STATS_INC(ip.drop);
00447       MIB2_STATS_INC(mib2.ipinhdrerrors);
00448       return ERR_OK;
00449     }
00450   }
00451 #endif
00452 
00453   /* copy IP addresses to aligned ip_addr_t */
00454   ip_addr_copy_from_ip4(ip_data.current_iphdr_dest, iphdr->dest);
00455   ip_addr_copy_from_ip4(ip_data.current_iphdr_src, iphdr->src);
00456 
00457   /* match packet against an interface, i.e. is this packet for us? */
00458   if (ip4_addr_ismulticast(ip4_current_dest_addr())) {
00459 #if LWIP_IGMP
00460     if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, ip4_current_dest_addr()))) {
00461       /* IGMP snooping switches need 0.0.0.0 to be allowed as source address (RFC 4541) */
00462       ip4_addr_t allsystems;
00463       IP4_ADDR(&allsystems, 224, 0, 0, 1);
00464       if (ip4_addr_cmp(ip4_current_dest_addr(), &allsystems) &&
00465           ip4_addr_isany(ip4_current_src_addr())) {
00466         check_ip_src = 0;
00467       }
00468       netif = inp;
00469     } else {
00470       netif = NULL;
00471     }
00472 #else /* LWIP_IGMP */
00473     if ((netif_is_up(inp)) && (!ip4_addr_isany_val(*netif_ip4_addr(inp)))) {
00474       netif = inp;
00475     } else {
00476       netif = NULL;
00477     }
00478 #endif /* LWIP_IGMP */
00479   } else {
00480     /* start trying with inp. if that's not acceptable, start walking the
00481        list of configured netifs.
00482        'first' is used as a boolean to mark whether we started walking the list */
00483     int first = 1;
00484     netif = inp;
00485     do {
00486       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",
00487           ip4_addr_get_u32(&iphdr->dest), ip4_addr_get_u32(netif_ip4_addr(netif)),
00488           ip4_addr_get_u32(&iphdr->dest) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
00489           ip4_addr_get_u32(netif_ip4_addr(netif)) & ip4_addr_get_u32(netif_ip4_netmask(netif)),
00490           ip4_addr_get_u32(&iphdr->dest) & ~ip4_addr_get_u32(netif_ip4_netmask(netif))));
00491 
00492       /* interface is up and configured? */
00493       if ((netif_is_up(netif)) && (!ip4_addr_isany_val(*netif_ip4_addr(netif)))) {
00494         /* unicast to this interface address? */
00495         if (ip4_addr_cmp(ip4_current_dest_addr(), netif_ip4_addr(netif)) ||
00496             /* or broadcast on this interface network address? */
00497             ip4_addr_isbroadcast(ip4_current_dest_addr(), netif)
00498 #if LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF
00499             || (ip4_addr_get_u32(ip4_current_dest_addr()) == PP_HTONL(IPADDR_LOOPBACK))
00500 #endif /* LWIP_NETIF_LOOPBACK && !LWIP_HAVE_LOOPIF */
00501             ) {
00502           LWIP_DEBUGF(IP_DEBUG, ("ip4_input: packet accepted on interface %c%c\n",
00503               netif->name[0], netif->name[1]));
00504           /* break out of for loop */
00505           break;
00506         }
00507 #if LWIP_AUTOIP
00508         /* connections to link-local addresses must persist after changing
00509            the netif's address (RFC3927 ch. 1.9) */
00510         if ((netif->autoip != NULL) &&
00511             ip4_addr_cmp(ip4_current_dest_addr(), &(netif->autoip->llipaddr))) {
00512           LWIP_DEBUGF(IP_DEBUG, ("ip4_input: LLA packet accepted on interface %c%c\n",
00513               netif->name[0], netif->name[1]));
00514           /* break out of for loop */
00515           break;
00516         }
00517 #endif /* LWIP_AUTOIP */
00518       }
00519       if (first) {
00520         first = 0;
00521         netif = netif_list;
00522       } else {
00523         netif = netif->next;
00524       }
00525       if (netif == inp) {
00526         netif = netif->next;
00527       }
00528     } while (netif != NULL);
00529   }
00530 
00531 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00532   /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
00533    * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
00534    * According to RFC 1542 section 3.1.1, referred by RFC 2131).
00535    *
00536    * If you want to accept private broadcast communication while a netif is down,
00537    * define LWIP_IP_ACCEPT_UDP_PORT(dst_port), e.g.:
00538    *
00539    * #define LWIP_IP_ACCEPT_UDP_PORT(dst_port) ((dst_port) == PP_NTOHS(12345))
00540    */
00541   if (netif == NULL) {
00542     /* remote port is DHCP server? */
00543     if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
00544       struct udp_hdr *udphdr = (struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen);
00545       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: UDP packet to DHCP client port %"U16_F"\n",
00546         ntohs(udphdr->dest)));
00547       if (IP_ACCEPT_LINK_LAYER_ADDRESSED_PORT(udphdr->dest)) {
00548         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: DHCP packet accepted.\n"));
00549         netif = inp;
00550         check_ip_src = 0;
00551       }
00552     }
00553   }
00554 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00555 
00556   /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
00557 #if LWIP_IGMP || IP_ACCEPT_LINK_LAYER_ADDRESSING
00558   if (check_ip_src
00559 #if IP_ACCEPT_LINK_LAYER_ADDRESSING
00560   /* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
00561       && !ip4_addr_isany_val(*ip4_current_src_addr())
00562 #endif /* IP_ACCEPT_LINK_LAYER_ADDRESSING */
00563      )
00564 #endif /* LWIP_IGMP || IP_ACCEPT_LINK_LAYER_ADDRESSING */
00565   {
00566     if ((ip4_addr_isbroadcast(ip4_current_src_addr(), inp)) ||
00567         (ip4_addr_ismulticast(ip4_current_src_addr()))) {
00568       /* packet source is not valid */
00569       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_WARNING, ("ip4_input: packet source is not valid.\n"));
00570       /* free (drop) packet pbufs */
00571       pbuf_free(p);
00572       IP_STATS_INC(ip.drop);
00573       MIB2_STATS_INC(mib2.ipinaddrerrors);
00574       MIB2_STATS_INC(mib2.ipindiscards);
00575       return ERR_OK;
00576     }
00577   }
00578 
00579   /* packet not for us? */
00580   if (netif == NULL) {
00581     /* packet not for us, route or discard */
00582     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE, ("ip4_input: packet not for us.\n"));
00583 #if IP_FORWARD
00584     /* non-broadcast packet? */
00585     if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), inp)) {
00586       /* try to forward IP packet on (other) interfaces */
00587       ip4_forward(p, iphdr, inp);
00588     } else
00589 #endif /* IP_FORWARD */
00590     {
00591       MIB2_STATS_INC(mib2.ipinaddrerrors);
00592       MIB2_STATS_INC(mib2.ipindiscards);
00593     }
00594     pbuf_free(p);
00595     return ERR_OK;
00596   }
00597   /* packet consists of multiple fragments? */
00598   if ((IPH_OFFSET(iphdr) & PP_HTONS(IP_OFFMASK | IP_MF)) != 0) {
00599 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
00600     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",
00601       ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), (u16_t)!!(IPH_OFFSET(iphdr) & PP_HTONS(IP_MF)), (u16_t)((ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8)));
00602     /* reassemble the packet*/
00603     p = ip4_reass(p);
00604     /* packet not fully reassembled yet? */
00605     if (p == NULL) {
00606       return ERR_OK;
00607     }
00608     iphdr = (struct ip_hdr *)p->payload;
00609 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
00610     pbuf_free(p);
00611     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
00612       ntohs(IPH_OFFSET(iphdr))));
00613     IP_STATS_INC(ip.opterr);
00614     IP_STATS_INC(ip.drop);
00615     /* unsupported protocol feature */
00616     MIB2_STATS_INC(mib2.ipinunknownprotos);
00617     return ERR_OK;
00618 #endif /* IP_REASSEMBLY */
00619   }
00620 
00621 #if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
00622 
00623 #if LWIP_IGMP
00624   /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
00625   if ((iphdr_hlen > IP_HLEN) &&  (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
00626 #else
00627   if (iphdr_hlen > IP_HLEN) {
00628 #endif /* LWIP_IGMP */
00629     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
00630     pbuf_free(p);
00631     IP_STATS_INC(ip.opterr);
00632     IP_STATS_INC(ip.drop);
00633     /* unsupported protocol feature */
00634     MIB2_STATS_INC(mib2.ipinunknownprotos);
00635     return ERR_OK;
00636   }
00637 #endif /* IP_OPTIONS_ALLOWED == 0 */
00638 
00639   /* send to upper layers */
00640   LWIP_DEBUGF(IP_DEBUG, ("ip4_input: \n"));
00641   ip4_debug_print(p);
00642   LWIP_DEBUGF(IP_DEBUG, ("ip4_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
00643 
00644   ip_data.current_netif = netif;
00645   ip_data.current_input_netif = inp;
00646   ip_data.current_ip4_header = iphdr;
00647   ip_data.current_ip_header_tot_len = IPH_HL(iphdr) * 4;
00648 
00649 #if LWIP_RAW
00650   /* raw input did not eat the packet? */
00651   if (raw_input(p, inp) == 0)
00652 #endif /* LWIP_RAW */
00653   {
00654     pbuf_header(p, -(s16_t)iphdr_hlen); /* Move to payload, no check necessary. */
00655 
00656     switch (IPH_PROTO(iphdr)) {
00657 #if LWIP_UDP
00658     case IP_PROTO_UDP:
00659 #if LWIP_UDPLITE
00660     case IP_PROTO_UDPLITE:
00661 #endif /* LWIP_UDPLITE */
00662       MIB2_STATS_INC(mib2.ipindelivers);
00663       udp_input(p, inp);
00664       break;
00665 #endif /* LWIP_UDP */
00666 #if LWIP_TCP
00667     case IP_PROTO_TCP:
00668       MIB2_STATS_INC(mib2.ipindelivers);
00669       tcp_input(p, inp);
00670       break;
00671 #endif /* LWIP_TCP */
00672 #if LWIP_ICMP
00673     case IP_PROTO_ICMP:
00674       MIB2_STATS_INC(mib2.ipindelivers);
00675       icmp_input(p, inp);
00676       break;
00677 #endif /* LWIP_ICMP */
00678 #if LWIP_IGMP
00679     case IP_PROTO_IGMP:
00680       igmp_input(p, inp, ip4_current_dest_addr());
00681       break;
00682 #endif /* LWIP_IGMP */
00683     default:
00684 #if LWIP_ICMP
00685       /* send ICMP destination protocol unreachable unless is was a broadcast */
00686       if (!ip4_addr_isbroadcast(ip4_current_dest_addr(), netif) &&
00687           !ip4_addr_ismulticast(ip4_current_dest_addr())) {
00688         pbuf_header_force(p, iphdr_hlen); /* Move to ip header, no check necessary. */
00689         p->payload = iphdr;
00690         icmp_dest_unreach(p, ICMP_DUR_PROTO);
00691       }
00692 #endif /* LWIP_ICMP */
00693       pbuf_free(p);
00694 
00695       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("Unsupported transport protocol %"U16_F"\n", (u16_t)IPH_PROTO(iphdr)));
00696 
00697       IP_STATS_INC(ip.proterr);
00698       IP_STATS_INC(ip.drop);
00699       MIB2_STATS_INC(mib2.ipinunknownprotos);
00700     }
00701   }
00702 
00703   /* @todo: this is not really necessary... */
00704   ip_data.current_netif = NULL;
00705   ip_data.current_input_netif = NULL;
00706   ip_data.current_ip4_header = NULL;
00707   ip_data.current_ip_header_tot_len = 0;
00708   ip4_addr_set_any(ip4_current_src_addr());
00709   ip4_addr_set_any(ip4_current_dest_addr());
00710 
00711   return ERR_OK;
00712 }
00713 
00714 /**
00715  * Sends an IP packet on a network interface. This function constructs
00716  * the IP header and calculates the IP header checksum. If the source
00717  * IP address is NULL, the IP address of the outgoing network
00718  * interface is filled in as source address.
00719  * If the destination IP address is IP_HDRINCL, p is assumed to already
00720  * include an IP header and p->payload points to it instead of the data.
00721  *
00722  * @param p the packet to send (p->payload points to the data, e.g. next
00723             protocol header; if dest == IP_HDRINCL, p already includes an IP
00724             header and p->payload points to that IP header)
00725  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00726  *         IP  address of the netif used to send is used as source address)
00727  * @param dest the destination IP address to send the packet to
00728  * @param ttl the TTL value to be set in the IP header
00729  * @param tos the TOS value to be set in the IP header
00730  * @param proto the PROTOCOL to be set in the IP header
00731  * @param netif the netif on which to send this packet
00732  * @return ERR_OK if the packet was sent OK
00733  *         ERR_BUF if p doesn't have enough space for IP/LINK headers
00734  *         returns errors returned by netif->output
00735  *
00736  * @note ip_id: RFC791 "some host may be able to simply use
00737  *  unique identifiers independent of destination"
00738  */
00739 err_t
00740 ip4_output_if(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00741              u8_t ttl, u8_t tos,
00742              u8_t proto, struct netif *netif)
00743 {
00744 #if IP_OPTIONS_SEND
00745   return ip4_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
00746 }
00747 
00748 /**
00749  * Same as ip_output_if() but with the possibility to include IP options:
00750  *
00751  * @ param ip_options pointer to the IP options, copied into the IP header
00752  * @ param optlen length of ip_options
00753  */
00754 err_t
00755 ip4_output_if_opt(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00756        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
00757        u16_t optlen)
00758 {
00759 #endif /* IP_OPTIONS_SEND */
00760   const ip4_addr_t *src_used = src;
00761   if (dest != IP_HDRINCL) {
00762     if (ip4_addr_isany(src)) {
00763       src_used = netif_ip4_addr(netif);
00764     }
00765   }
00766 
00767 #if IP_OPTIONS_SEND
00768   return ip4_output_if_opt_src(p, src_used, dest, ttl, tos, proto, netif,
00769     ip_options, optlen);
00770 #else /* IP_OPTIONS_SEND */
00771   return ip4_output_if_src(p, src_used, dest, ttl, tos, proto, netif);
00772 #endif /* IP_OPTIONS_SEND */
00773 }
00774 
00775 /**
00776  * Same as ip_output_if() but 'src' address is not replaced by netif address
00777  * when it is 'any'.
00778  */
00779 err_t
00780 ip4_output_if_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00781              u8_t ttl, u8_t tos,
00782              u8_t proto, struct netif *netif)
00783 {
00784 #if IP_OPTIONS_SEND
00785   return ip4_output_if_opt_src(p, src, dest, ttl, tos, proto, netif, NULL, 0);
00786 }
00787 
00788 /**
00789  * Same as ip_output_if_opt() but 'src' address is not replaced by netif address
00790  * when it is 'any'.
00791  */
00792 err_t
00793 ip4_output_if_opt_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00794        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
00795        u16_t optlen)
00796 {
00797 #endif /* IP_OPTIONS_SEND */
00798   struct ip_hdr *iphdr;
00799   ip4_addr_t dest_addr;
00800 #if CHECKSUM_GEN_IP_INLINE
00801   u32_t chk_sum = 0;
00802 #endif /* CHECKSUM_GEN_IP_INLINE */
00803 
00804   LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
00805 
00806   MIB2_STATS_INC(mib2.ipoutrequests);
00807 
00808   /* Should the IP header be generated or is it already included in p? */
00809   if (dest != IP_HDRINCL) {
00810     u16_t ip_hlen = IP_HLEN;
00811 #if IP_OPTIONS_SEND
00812     u16_t optlen_aligned = 0;
00813     if (optlen != 0) {
00814 #if CHECKSUM_GEN_IP_INLINE
00815       int i;
00816 #endif /* CHECKSUM_GEN_IP_INLINE */
00817       /* round up to a multiple of 4 */
00818       optlen_aligned = ((optlen + 3) & ~3);
00819       ip_hlen += optlen_aligned;
00820       /* First write in the IP options */
00821       if (pbuf_header(p, optlen_aligned)) {
00822         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output_if_opt: not enough room for IP options in pbuf\n"));
00823         IP_STATS_INC(ip.err);
00824         MIB2_STATS_INC(mib2.ipoutdiscards);
00825         return ERR_BUF;
00826       }
00827       MEMCPY(p->payload, ip_options, optlen);
00828       if (optlen < optlen_aligned) {
00829         /* zero the remaining bytes */
00830         memset(((char*)p->payload) + optlen, 0, optlen_aligned - optlen);
00831       }
00832 #if CHECKSUM_GEN_IP_INLINE
00833       for (i = 0; i < optlen_aligned/2; i++) {
00834         chk_sum += ((u16_t*)p->payload)[i];
00835       }
00836 #endif /* CHECKSUM_GEN_IP_INLINE */
00837     }
00838 #endif /* IP_OPTIONS_SEND */
00839     /* generate IP header */
00840     if (pbuf_header(p, IP_HLEN)) {
00841       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip4_output: not enough room for IP header in pbuf\n"));
00842 
00843       IP_STATS_INC(ip.err);
00844       MIB2_STATS_INC(mib2.ipoutdiscards);
00845       return ERR_BUF;
00846     }
00847 
00848     iphdr = (struct ip_hdr *)p->payload;
00849     LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
00850                (p->len >= sizeof(struct ip_hdr)));
00851 
00852     IPH_TTL_SET(iphdr, ttl);
00853     IPH_PROTO_SET(iphdr, proto);
00854 #if CHECKSUM_GEN_IP_INLINE
00855     chk_sum += LWIP_MAKE_U16(proto, ttl);
00856 #endif /* CHECKSUM_GEN_IP_INLINE */
00857 
00858     /* dest cannot be NULL here */
00859     ip4_addr_copy(iphdr->dest, *dest);
00860 #if CHECKSUM_GEN_IP_INLINE
00861     chk_sum += ip4_addr_get_u32(&iphdr->dest) & 0xFFFF;
00862     chk_sum += ip4_addr_get_u32(&iphdr->dest) >> 16;
00863 #endif /* CHECKSUM_GEN_IP_INLINE */
00864 
00865     IPH_VHL_SET(iphdr, 4, ip_hlen / 4);
00866     IPH_TOS_SET(iphdr, tos);
00867 #if CHECKSUM_GEN_IP_INLINE
00868     chk_sum += LWIP_MAKE_U16(tos, iphdr->_v_hl);
00869 #endif /* CHECKSUM_GEN_IP_INLINE */
00870     IPH_LEN_SET(iphdr, htons(p->tot_len));
00871 #if CHECKSUM_GEN_IP_INLINE
00872     chk_sum += iphdr->_len;
00873 #endif /* CHECKSUM_GEN_IP_INLINE */
00874     IPH_OFFSET_SET(iphdr, 0);
00875     IPH_ID_SET(iphdr, htons(ip_id));
00876 #if CHECKSUM_GEN_IP_INLINE
00877     chk_sum += iphdr->_id;
00878 #endif /* CHECKSUM_GEN_IP_INLINE */
00879     ++ip_id;
00880 
00881     if (src == NULL) {
00882       ip4_addr_copy(iphdr->src, *IP4_ADDR_ANY);
00883     } else {
00884       /* src cannot be NULL here */
00885       ip4_addr_copy(iphdr->src, *src);
00886     }
00887 
00888 #if CHECKSUM_GEN_IP_INLINE
00889     chk_sum += ip4_addr_get_u32(&iphdr->src) & 0xFFFF;
00890     chk_sum += ip4_addr_get_u32(&iphdr->src) >> 16;
00891     chk_sum = (chk_sum >> 16) + (chk_sum & 0xFFFF);
00892     chk_sum = (chk_sum >> 16) + chk_sum;
00893     chk_sum = ~chk_sum;
00894     IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
00895       iphdr->_chksum = (u16_t)chk_sum; /* network order */
00896     }
00897 #if LWIP_CHECKSUM_CTRL_PER_NETIF
00898     else {
00899       IPH_CHKSUM_SET(iphdr, 0);
00900     }
00901 #endif /* LWIP_CHECKSUM_CTRL_PER_NETIF*/
00902 #else /* CHECKSUM_GEN_IP_INLINE */
00903     IPH_CHKSUM_SET(iphdr, 0);
00904 #if CHECKSUM_GEN_IP
00905     IF__NETIF_CHECKSUM_ENABLED(netif, NETIF_CHECKSUM_GEN_IP) {
00906       IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
00907     }
00908 #endif /* CHECKSUM_GEN_IP */
00909 #endif /* CHECKSUM_GEN_IP_INLINE */
00910   } else {
00911     /* IP header already included in p */
00912     iphdr = (struct ip_hdr *)p->payload;
00913     ip4_addr_copy(dest_addr, iphdr->dest);
00914     dest = &dest_addr;
00915   }
00916 
00917   IP_STATS_INC(ip.xmit);
00918 
00919   LWIP_DEBUGF(IP_DEBUG, ("ip4_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], (u16_t)netif->num));
00920   ip4_debug_print(p);
00921 
00922 #if ENABLE_LOOPBACK
00923   if (ip4_addr_cmp(dest, netif_ip4_addr(netif))
00924 #if !LWIP_HAVE_LOOPIF
00925       || ip4_addr_isloopback(dest)
00926 #endif /* !LWIP_HAVE_LOOPIF */
00927       ) {
00928     /* Packet to self, enqueue it for loopback */
00929     LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
00930     return netif_loop_output(netif, p);
00931   }
00932 #if LWIP_MULTICAST_TX_OPTIONS
00933   if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
00934     netif_loop_output(netif, p);
00935   }
00936 #endif /* LWIP_MULTICAST_TX_OPTIONS */
00937 #endif /* ENABLE_LOOPBACK */
00938 #if IP_FRAG
00939   /* don't fragment if interface has mtu set to 0 [loopif] */
00940   if (netif->mtu && (p->tot_len > netif->mtu)) {
00941     return ip4_frag(p, netif, dest);
00942   }
00943 #endif /* IP_FRAG */
00944 
00945   LWIP_DEBUGF(IP_DEBUG, ("ip4_output_if: call netif->output()\n"));
00946   return netif->output(netif, p, dest);
00947 }
00948 
00949 /**
00950  * Simple interface to ip_output_if. It finds the outgoing network
00951  * interface and calls upon ip_output_if to do the actual work.
00952  *
00953  * @param p the packet to send (p->payload points to the data, e.g. next
00954             protocol header; if dest == IP_HDRINCL, p already includes an IP
00955             header and p->payload points to that IP header)
00956  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00957  *         IP  address of the netif used to send is used as source address)
00958  * @param dest the destination IP address to send the packet to
00959  * @param ttl the TTL value to be set in the IP header
00960  * @param tos the TOS value to be set in the IP header
00961  * @param proto the PROTOCOL to be set in the IP header
00962  *
00963  * @return ERR_RTE if no route is found
00964  *         see ip_output_if() for more return values
00965  */
00966 err_t
00967 ip4_output(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
00968           u8_t ttl, u8_t tos, u8_t proto)
00969 {
00970   struct netif *netif;
00971 
00972   LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
00973 
00974   if ((netif = ip4_route_src(dest, src)) == NULL) {
00975     LWIP_DEBUGF(IP_DEBUG, ("ip4_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
00976       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
00977     IP_STATS_INC(ip.rterr);
00978     return ERR_RTE;
00979   }
00980 
00981   return ip4_output_if(p, src, dest, ttl, tos, proto, netif);
00982 }
00983 
00984 #if LWIP_NETIF_HWADDRHINT
00985 /** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
00986  *  before calling ip_output_if.
00987  *
00988  * @param p the packet to send (p->payload points to the data, e.g. next
00989             protocol header; if dest == IP_HDRINCL, p already includes an IP
00990             header and p->payload points to that IP header)
00991  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00992  *         IP  address of the netif used to send is used as source address)
00993  * @param dest the destination IP address to send the packet to
00994  * @param ttl the TTL value to be set in the IP header
00995  * @param tos the TOS value to be set in the IP header
00996  * @param proto the PROTOCOL to be set in the IP header
00997  * @param addr_hint address hint pointer set to netif->addr_hint before
00998  *        calling ip_output_if()
00999  *
01000  * @return ERR_RTE if no route is found
01001  *         see ip_output_if() for more return values
01002  */
01003 err_t
01004 ip4_output_hinted(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
01005           u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
01006 {
01007   struct netif *netif;
01008   err_t err;
01009 
01010   LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p);
01011 
01012   if ((netif = ip4_route_src(dest, src)) == NULL) {
01013     LWIP_DEBUGF(IP_DEBUG, ("ip4_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
01014       ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
01015     IP_STATS_INC(ip.rterr);
01016     return ERR_RTE;
01017   }
01018 
01019   NETIF_SET_HWADDRHINT(netif, addr_hint);
01020   err = ip4_output_if(p, src, dest, ttl, tos, proto, netif);
01021   NETIF_SET_HWADDRHINT(netif, NULL);
01022 
01023   return err;
01024 }
01025 #endif /* LWIP_NETIF_HWADDRHINT*/
01026 
01027 #if IP_DEBUG
01028 /* Print an IP header by using LWIP_DEBUGF
01029  * @param p an IP packet, p->payload pointing to the IP header
01030  */
01031 void
01032 ip4_debug_print(struct pbuf *p)
01033 {
01034   struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
01035 
01036   LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
01037   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01038   LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" |  0x%02"X16_F" |     %5"U16_F"     | (v, hl, tos, len)\n",
01039                     (u16_t)IPH_V(iphdr),
01040                     (u16_t)IPH_HL(iphdr),
01041                     (u16_t)IPH_TOS(iphdr),
01042                     ntohs(IPH_LEN(iphdr))));
01043   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01044   LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      |%"U16_F"%"U16_F"%"U16_F"|    %4"U16_F"   | (id, flags, offset)\n",
01045                     ntohs(IPH_ID(iphdr)),
01046                     (u16_t)(ntohs(IPH_OFFSET(iphdr)) >> 15 & 1),
01047                     (u16_t)(ntohs(IPH_OFFSET(iphdr)) >> 14 & 1),
01048                     (u16_t)(ntohs(IPH_OFFSET(iphdr)) >> 13 & 1),
01049                     (u16_t)(ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)));
01050   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01051   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |    0x%04"X16_F"     | (ttl, proto, chksum)\n",
01052                     (u16_t)IPH_TTL(iphdr),
01053                     (u16_t)IPH_PROTO(iphdr),
01054                     ntohs(IPH_CHKSUM(iphdr))));
01055   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01056   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (src)\n",
01057                     ip4_addr1_16(&iphdr->src),
01058                     ip4_addr2_16(&iphdr->src),
01059                     ip4_addr3_16(&iphdr->src),
01060                     ip4_addr4_16(&iphdr->src)));
01061   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01062   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (dest)\n",
01063                     ip4_addr1_16(&iphdr->dest),
01064                     ip4_addr2_16(&iphdr->dest),
01065                     ip4_addr3_16(&iphdr->dest),
01066                     ip4_addr4_16(&iphdr->dest)));
01067   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
01068 }
01069 #endif /* IP_DEBUG */
01070 
01071 #endif /* LWIP_IPV4 */