ip.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 #include "lwip/ip.h"
00043 #include "lwip/def.h"
00044 #include "lwip/mem.h"
00045 #include "lwip/ip_frag.h"
00046 #include "lwip/inet.h"
00047 #include "lwip/inet_chksum.h"
00048 #include "lwip/netif.h"
00049 #include "lwip/icmp.h"
00050 #include "lwip/igmp.h"
00051 #include "lwip/raw.h"
00052 #include "lwip/udp.h"
00053 #include "lwip/tcp.h"
00054 #include "lwip/snmp.h"
00055 #include "lwip/dhcp.h "
00056 #include "lwip/stats.h"
00057 #include "arch/perf.h"
00058 
00059 #include <string.h>
00060 
00061 /**
00062  * The interface that provided the packet for the current callback
00063  * invocation.
00064  */
00065 struct netif *current_netif;
00066 
00067 /**
00068  * Header of the input packet currently being processed.
00069  */
00070 const struct ip_hdr *current_header;
00071 
00072 /**
00073  * Finds the appropriate network interface for a given IP address. It
00074  * searches the list of network interfaces linearly. A match is found
00075  * if the masked IP address of the network interface equals the masked
00076  * IP address given to the function.
00077  *
00078  * @param dest the destination IP address for which to find the route
00079  * @return the netif on which to send to reach dest
00080  */
00081 struct netif *
00082 ip_route(struct ip_addr *dest)
00083 {
00084   struct netif *netif;
00085 
00086   /* iterate through netifs */
00087   for(netif = netif_list; netif != NULL; netif = netif->next) {
00088     /* network mask matches? */
00089     if (netif_is_up(netif)) {
00090       if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {
00091         /* return netif on which to forward IP packet */
00092         return netif;
00093       }
00094     }
00095   }
00096   if ((netif_default == NULL) || (!netif_is_up(netif_default))) {
00097     LWIP_DEBUGF(IP_DEBUG | 2, ("ip_route: No route to 0x%"X32_F"\n", dest->addr));
00098     IP_STATS_INC(ip.rterr);
00099     snmp_inc_ipoutnoroutes();
00100     return NULL;
00101   }
00102   /* no matching netif found, use default netif */
00103   return netif_default;
00104 }
00105 
00106 #if IP_FORWARD
00107 /**
00108  * Forwards an IP packet. It finds an appropriate route for the
00109  * packet, decrements the TTL value of the packet, adjusts the
00110  * checksum and outputs the packet on the appropriate interface.
00111  *
00112  * @param p the packet to forward (p->payload points to IP header)
00113  * @param iphdr the IP header of the input packet
00114  * @param inp the netif on which this packet was received
00115  * @return the netif on which the packet was sent (NULL if it wasn't sent)
00116  */
00117 static struct netif *
00118 ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
00119 {
00120   struct netif *netif;
00121 
00122   PERF_START;
00123   /* Find network interface where to forward this IP packet to. */
00124   netif = ip_route((struct ip_addr *)&(iphdr->dest));
00125   if (netif == NULL) {
00126     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for 0x%"X32_F" found\n",
00127                       iphdr->dest.addr));
00128     snmp_inc_ipoutnoroutes();
00129     return (struct netif *)NULL;
00130   }
00131   /* Do not forward packets onto the same network interface on which
00132    * they arrived. */
00133   if (netif == inp) {
00134     LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));
00135     snmp_inc_ipoutnoroutes();
00136     return (struct netif *)NULL;
00137   }
00138 
00139   /* decrement TTL */
00140   IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);
00141   /* send ICMP if TTL == 0 */
00142   if (IPH_TTL(iphdr) == 0) {
00143     snmp_inc_ipinhdrerrors();
00144 #if LWIP_ICMP
00145     /* Don't send ICMP messages in response to ICMP messages */
00146     if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {
00147       icmp_time_exceeded(p, ICMP_TE_TTL);
00148     }
00149 #endif /* LWIP_ICMP */
00150     return (struct netif *)NULL;
00151   }
00152 
00153   /* Incrementally update the IP checksum. */
00154   if (IPH_CHKSUM(iphdr) >= htons(0xffff - 0x100)) {
00155     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100) + 1);
00156   } else {
00157     IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100));
00158   }
00159 
00160   LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to 0x%"X32_F"\n",
00161                     iphdr->dest.addr));
00162 
00163   IP_STATS_INC(ip.fw);
00164   IP_STATS_INC(ip.xmit);
00165   snmp_inc_ipforwdatagrams();
00166 
00167   PERF_STOP("ip_forward");
00168   /* transmit pbuf on chosen interface */
00169   netif->output(netif, p, (struct ip_addr *)&(iphdr->dest));
00170   return netif;
00171 }
00172 #endif /* IP_FORWARD */
00173 
00174 /**
00175  * This function is called by the network interface device driver when
00176  * an IP packet is received. The function does the basic checks of the
00177  * IP header such as packet size being at least larger than the header
00178  * size etc. If the packet was not destined for us, the packet is
00179  * forwarded (using ip_forward). The IP checksum is always checked.
00180  *
00181  * Finally, the packet is sent to the upper layer protocol input function.
00182  * 
00183  * @param p the received IP packet (p->payload points to IP header)
00184  * @param inp the netif on which this packet was received
00185  * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
00186  *         processed, but currently always returns ERR_OK)
00187  */
00188 err_t
00189 ip_input(struct pbuf *p, struct netif *inp)
00190 {
00191   struct ip_hdr *iphdr;
00192   struct netif *netif;
00193   u16_t iphdr_hlen;
00194   u16_t iphdr_len;
00195 #if LWIP_DHCP
00196   int check_ip_src=1;
00197 #endif /* LWIP_DHCP */
00198 
00199   IP_STATS_INC(ip.recv);
00200   snmp_inc_ipinreceives();
00201 
00202   /* identify the IP header */
00203   iphdr = (struct ip_hdr *)p->payload;
00204   if (IPH_V(iphdr) != 4) {
00205     LWIP_DEBUGF(IP_DEBUG | 1, ("IP packet dropped due to bad version number %"U16_F"\n", IPH_V(iphdr)));
00206     ip_debug_print(p);
00207     pbuf_free(p);
00208     IP_STATS_INC(ip.err);
00209     IP_STATS_INC(ip.drop);
00210     snmp_inc_ipinhdrerrors();
00211     return ERR_OK;
00212   }
00213 
00214   /* obtain IP header length in number of 32-bit words */
00215   iphdr_hlen = IPH_HL(iphdr);
00216   /* calculate IP header length in bytes */
00217   iphdr_hlen *= 4;
00218   /* obtain ip length in bytes */
00219   iphdr_len = ntohs(IPH_LEN(iphdr));
00220 
00221   /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
00222   if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len)) {
00223     if (iphdr_hlen > p->len)
00224     LWIP_DEBUGF(IP_DEBUG | 2, ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
00225                                iphdr_hlen, p->len));
00226     if (iphdr_len > p->tot_len)
00227     LWIP_DEBUGF(IP_DEBUG | 2, ("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), "
00228                                "IP packet dropped.\n",
00229                                iphdr_len, p->tot_len));
00230     /* free (drop) packet pbufs */
00231     pbuf_free(p);
00232     IP_STATS_INC(ip.lenerr);
00233     IP_STATS_INC(ip.drop);
00234     snmp_inc_ipindiscards();
00235     return ERR_OK;
00236   }
00237 
00238   /* verify checksum */
00239 #if CHECKSUM_CHECK_IP
00240   if (inet_chksum(iphdr, iphdr_hlen) != 0) {
00241 
00242     LWIP_DEBUGF(IP_DEBUG | 2, ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
00243     ip_debug_print(p);
00244     pbuf_free(p);
00245     IP_STATS_INC(ip.chkerr);
00246     IP_STATS_INC(ip.drop);
00247     snmp_inc_ipinhdrerrors();
00248     return ERR_OK;
00249   }
00250 #endif
00251 
00252   /* Trim pbuf. This should have been done at the netif layer,
00253    * but we'll do it anyway just to be sure that its done. */
00254   pbuf_realloc(p, iphdr_len);
00255 
00256   /* match packet against an interface, i.e. is this packet for us? */
00257 #if LWIP_IGMP
00258   if (ip_addr_ismulticast(&(iphdr->dest))) {
00259     if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, &(iphdr->dest)))) {
00260       netif = inp;
00261     } else {
00262       netif = NULL;
00263     }
00264   } else
00265 #endif /* LWIP_IGMP */
00266   {
00267     /* start trying with inp. if that's not acceptable, start walking the
00268        list of configured netifs.
00269        'first' is used as a boolean to mark whether we started walking the list */
00270     int first = 1;
00271     netif = inp;
00272     do {
00273       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",
00274           iphdr->dest.addr, netif->ip_addr.addr,
00275           iphdr->dest.addr & netif->netmask.addr,
00276           netif->ip_addr.addr & netif->netmask.addr,
00277           iphdr->dest.addr & ~(netif->netmask.addr)));
00278 
00279       /* interface is up and configured? */
00280       if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) {
00281         /* unicast to this interface address? */
00282         if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
00283             /* or broadcast on this interface network address? */
00284             ip_addr_isbroadcast(&(iphdr->dest), netif)) {
00285           LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
00286               netif->name[0], netif->name[1]));
00287           /* break out of for loop */
00288           break;
00289         }
00290       }
00291       if (first) {
00292         first = 0;
00293         netif = netif_list;
00294       } else {
00295         netif = netif->next;
00296       }
00297       if (netif == inp) {
00298         netif = netif->next;
00299       }
00300     } while(netif != NULL);
00301   }
00302 
00303 #if LWIP_DHCP
00304   /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
00305    * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
00306    * According to RFC 1542 section 3.1.1, referred by RFC 2131).
00307    */
00308   if (netif == NULL) {
00309     /* remote port is DHCP server? */
00310     if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
00311       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
00312         ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen))->dest)));
00313       if (ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen))->dest) == DHCP_CLIENT_PORT) {
00314         LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: DHCP packet accepted.\n"));
00315         netif = inp;
00316         check_ip_src = 0;
00317       }
00318     }
00319   }
00320 #endif /* LWIP_DHCP */
00321 
00322   /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
00323 #if LWIP_DHCP
00324   /* DHCP servers need 0.0.0.0 to be allowed as source address (RFC 1.1.2.2: 3.2.1.3/a) */
00325   if (check_ip_src && (iphdr->src.addr != 0))
00326 #endif /* LWIP_DHCP */
00327   {  if ((ip_addr_isbroadcast(&(iphdr->src), inp)) ||
00328          (ip_addr_ismulticast(&(iphdr->src)))) {
00329       /* packet source is not valid */
00330       LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: packet source is not valid.\n"));
00331       /* free (drop) packet pbufs */
00332       pbuf_free(p);
00333       IP_STATS_INC(ip.drop);
00334       snmp_inc_ipinaddrerrors();
00335       snmp_inc_ipindiscards();
00336       return ERR_OK;
00337     }
00338   }
00339 
00340   /* packet not for us? */
00341   if (netif == NULL) {
00342     /* packet not for us, route or discard */
00343     LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: packet not for us.\n"));
00344 #if IP_FORWARD
00345     /* non-broadcast packet? */
00346     if (!ip_addr_isbroadcast(&(iphdr->dest), inp)) {
00347       /* try to forward IP packet on (other) interfaces */
00348       ip_forward(p, iphdr, inp);
00349     } else
00350 #endif /* IP_FORWARD */
00351     {
00352       snmp_inc_ipinaddrerrors();
00353       snmp_inc_ipindiscards();
00354     }
00355     pbuf_free(p);
00356     return ERR_OK;
00357   }
00358   /* packet consists of multiple fragments? */
00359   if ((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
00360 #if IP_REASSEMBLY /* packet fragment reassembly code present? */
00361     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",
00362       ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & htons(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
00363     /* reassemble the packet*/
00364     p = ip_reass(p);
00365     /* packet not fully reassembled yet? */
00366     if (p == NULL) {
00367       return ERR_OK;
00368     }
00369     iphdr = (struct ip_hdr *)p->payload;
00370 #else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
00371     pbuf_free(p);
00372     LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
00373       ntohs(IPH_OFFSET(iphdr))));
00374     IP_STATS_INC(ip.opterr);
00375     IP_STATS_INC(ip.drop);
00376     /* unsupported protocol feature */
00377     snmp_inc_ipinunknownprotos();
00378     return ERR_OK;
00379 #endif /* IP_REASSEMBLY */
00380   }
00381 
00382 #if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */
00383 
00384 #if LWIP_IGMP
00385   /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
00386   if((iphdr_hlen > IP_HLEN &&  (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
00387 #else
00388   if (iphdr_hlen > IP_HLEN) {
00389 #endif /* LWIP_IGMP */
00390     LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
00391     pbuf_free(p);
00392     IP_STATS_INC(ip.opterr);
00393     IP_STATS_INC(ip.drop);
00394     /* unsupported protocol feature */
00395     snmp_inc_ipinunknownprotos();
00396     return ERR_OK;
00397   }
00398 #endif /* IP_OPTIONS_ALLOWED == 0 */
00399 
00400   /* send to upper layers */
00401   LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
00402   ip_debug_print(p);
00403   LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));
00404 
00405   current_netif = inp;
00406   current_header = iphdr;
00407 
00408 #if LWIP_RAW
00409   /* raw input did not eat the packet? */
00410   if (raw_input(p, inp) == 0)
00411 #endif /* LWIP_RAW */
00412   {
00413 
00414     switch (IPH_PROTO(iphdr)) {
00415 #if LWIP_UDP
00416     case IP_PROTO_UDP:
00417 #if LWIP_UDPLITE
00418     case IP_PROTO_UDPLITE:
00419 #endif /* LWIP_UDPLITE */
00420       snmp_inc_ipindelivers();
00421       udp_input(p, inp);
00422       break;
00423 #endif /* LWIP_UDP */
00424 #if LWIP_TCP
00425     case IP_PROTO_TCP:
00426       snmp_inc_ipindelivers();
00427       tcp_input(p, inp);
00428       break;
00429 #endif /* LWIP_TCP */
00430 #if LWIP_ICMP
00431     case IP_PROTO_ICMP:
00432       snmp_inc_ipindelivers();
00433       icmp_input(p, inp);
00434       break;
00435 #endif /* LWIP_ICMP */
00436 #if LWIP_IGMP
00437     case IP_PROTO_IGMP:
00438       igmp_input(p,inp,&(iphdr->dest));
00439       break;
00440 #endif /* LWIP_IGMP */
00441     default:
00442 #if LWIP_ICMP
00443       /* send ICMP destination protocol unreachable unless is was a broadcast */
00444       if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
00445           !ip_addr_ismulticast(&(iphdr->dest))) {
00446         p->payload = iphdr;
00447         icmp_dest_unreach(p, ICMP_DUR_PROTO);
00448       }
00449 #endif /* LWIP_ICMP */
00450       pbuf_free(p);
00451 
00452       LWIP_DEBUGF(IP_DEBUG | 2, ("Unsupported transport protocol %"U16_F"\n", IPH_PROTO(iphdr)));
00453 
00454       IP_STATS_INC(ip.proterr);
00455       IP_STATS_INC(ip.drop);
00456       snmp_inc_ipinunknownprotos();
00457     }
00458   }
00459 
00460   current_netif = NULL;
00461   current_header = NULL;
00462 
00463   return ERR_OK;
00464 }
00465 
00466 /**
00467  * Sends an IP packet on a network interface. This function constructs
00468  * the IP header and calculates the IP header checksum. If the source
00469  * IP address is NULL, the IP address of the outgoing network
00470  * interface is filled in as source address.
00471  * If the destination IP address is IP_HDRINCL, p is assumed to already
00472  * include an IP header and p->payload points to it instead of the data.
00473  *
00474  * @param p the packet to send (p->payload points to the data, e.g. next
00475             protocol header; if dest == IP_HDRINCL, p already includes an IP
00476             header and p->payload points to that IP header)
00477  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00478  *         IP  address of the netif used to send is used as source address)
00479  * @param dest the destination IP address to send the packet to
00480  * @param ttl the TTL value to be set in the IP header
00481  * @param tos the TOS value to be set in the IP header
00482  * @param proto the PROTOCOL to be set in the IP header
00483  * @param netif the netif on which to send this packet
00484  * @return ERR_OK if the packet was sent OK
00485  *         ERR_BUF if p doesn't have enough space for IP/LINK headers
00486  *         returns errors returned by netif->output
00487  *
00488  * @note ip_id: RFC791 "some host may be able to simply use
00489  *  unique identifiers independent of destination"
00490  */
00491 err_t
00492 ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
00493              u8_t ttl, u8_t tos,
00494              u8_t proto, struct netif *netif)
00495 {
00496 #if IP_OPTIONS_SEND
00497   return ip_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
00498 }
00499 
00500 /**
00501  * Same as ip_output_if() but with the possibility to include IP options:
00502  *
00503  * @ param ip_options pointer to the IP options, copied into the IP header
00504  * @ param optlen length of ip_options
00505  */
00506 err_t ip_output_if_opt(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
00507        u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
00508        u16_t optlen)
00509 {
00510 #endif /* IP_OPTIONS_SEND */
00511   struct ip_hdr *iphdr;
00512   static u16_t ip_id = 0;
00513 
00514   snmp_inc_ipoutrequests();
00515 
00516   /* Should the IP header be generated or is it already included in p? */
00517   if (dest != IP_HDRINCL) {
00518     u16_t ip_hlen = IP_HLEN;
00519 #if IP_OPTIONS_SEND
00520     u16_t optlen_aligned = 0;
00521     if (optlen != 0) {
00522       /* round up to a multiple of 4 */
00523       optlen_aligned = ((optlen + 3) & ~3);
00524       ip_hlen += optlen_aligned;
00525       /* First write in the IP options */
00526       if (pbuf_header(p, optlen_aligned)) {
00527         LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output_if_opt: not enough room for IP options in pbuf\n"));
00528         IP_STATS_INC(ip.err);
00529         snmp_inc_ipoutdiscards();
00530         return ERR_BUF;
00531       }
00532       MEMCPY(p->payload, ip_options, optlen);
00533       if (optlen < optlen_aligned) {
00534         /* zero the remaining bytes */
00535         memset(((char*)p->payload) + optlen, 0, optlen_aligned - optlen);
00536       }
00537     }
00538 #endif /* IP_OPTIONS_SEND */
00539     /* generate IP header */
00540     if (pbuf_header(p, IP_HLEN)) {
00541       LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: not enough room for IP header in pbuf\n"));
00542 
00543       IP_STATS_INC(ip.err);
00544       snmp_inc_ipoutdiscards();
00545       return ERR_BUF;
00546     }
00547 
00548     iphdr = (struct ip_hdr *)p->payload;
00549     LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
00550                (p->len >= sizeof(struct ip_hdr)));
00551 
00552     IPH_TTL_SET(iphdr, ttl);
00553     IPH_PROTO_SET(iphdr, proto);
00554 
00555     ip_addr_set(&(iphdr->dest), dest);
00556 
00557     IPH_VHLTOS_SET(iphdr, 4, ip_hlen / 4, tos);
00558     IPH_LEN_SET(iphdr, htons(p->tot_len));
00559     IPH_OFFSET_SET(iphdr, 0);
00560     IPH_ID_SET(iphdr, htons(ip_id));
00561     ++ip_id;
00562 
00563     if (ip_addr_isany(src)) {
00564       ip_addr_set(&(iphdr->src), &(netif->ip_addr));
00565     } else {
00566       ip_addr_set(&(iphdr->src), src);
00567     }
00568 
00569     IPH_CHKSUM_SET(iphdr, 0);
00570 #if CHECKSUM_GEN_IP
00571     IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
00572 #endif
00573   } else {
00574     /* IP header already included in p */
00575     iphdr = (struct ip_hdr *)p->payload;
00576     dest = &(iphdr->dest);
00577   }
00578 
00579   IP_STATS_INC(ip.xmit);
00580 
00581   LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
00582   ip_debug_print(p);
00583 
00584 #if ENABLE_LOOPBACK
00585   if (ip_addr_cmp(dest, &netif->ip_addr)) {
00586     /* Packet to self, enqueue it for loopback */
00587     LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
00588     return netif_loop_output(netif, p, dest);
00589   }
00590 #endif /* ENABLE_LOOPBACK */
00591 #if IP_FRAG
00592   /* don't fragment if interface has mtu set to 0 [loopif] */
00593   if (netif->mtu && (p->tot_len > netif->mtu)) {
00594     return ip_frag(p,netif,dest);
00595   }
00596 #endif
00597 
00598   LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
00599   return netif->output(netif, p, dest);
00600 }
00601 
00602 /**
00603  * Simple interface to ip_output_if. It finds the outgoing network
00604  * interface and calls upon ip_output_if to do the actual work.
00605  *
00606  * @param p the packet to send (p->payload points to the data, e.g. next
00607             protocol header; if dest == IP_HDRINCL, p already includes an IP
00608             header and p->payload points to that IP header)
00609  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00610  *         IP  address of the netif used to send is used as source address)
00611  * @param dest the destination IP address to send the packet to
00612  * @param ttl the TTL value to be set in the IP header
00613  * @param tos the TOS value to be set in the IP header
00614  * @param proto the PROTOCOL to be set in the IP header
00615  *
00616  * @return ERR_RTE if no route is found
00617  *         see ip_output_if() for more return values
00618  */
00619 err_t
00620 ip_output(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
00621           u8_t ttl, u8_t tos, u8_t proto)
00622 {
00623   struct netif *netif;
00624 
00625   if ((netif = ip_route(dest)) == NULL) {
00626     LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
00627     IP_STATS_INC(ip.rterr);
00628     return ERR_RTE;
00629   }
00630 
00631   return ip_output_if(p, src, dest, ttl, tos, proto, netif);
00632 }
00633 
00634 #if LWIP_NETIF_HWADDRHINT
00635 /** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
00636  *  before calling ip_output_if.
00637  *
00638  * @param p the packet to send (p->payload points to the data, e.g. next
00639             protocol header; if dest == IP_HDRINCL, p already includes an IP
00640             header and p->payload points to that IP header)
00641  * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
00642  *         IP  address of the netif used to send is used as source address)
00643  * @param dest the destination IP address to send the packet to
00644  * @param ttl the TTL value to be set in the IP header
00645  * @param tos the TOS value to be set in the IP header
00646  * @param proto the PROTOCOL to be set in the IP header
00647  * @param addr_hint address hint pointer set to netif->addr_hint before
00648  *        calling ip_output_if()
00649  *
00650  * @return ERR_RTE if no route is found
00651  *         see ip_output_if() for more return values
00652  */
00653 err_t
00654 ip_output_hinted(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
00655           u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
00656 {
00657   struct netif *netif;
00658   err_t err;
00659 
00660   if ((netif = ip_route(dest)) == NULL) {
00661     LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));
00662     IP_STATS_INC(ip.rterr);
00663     return ERR_RTE;
00664   }
00665 
00666   netif->addr_hint = addr_hint;
00667   err = ip_output_if(p, src, dest, ttl, tos, proto, netif);
00668   netif->addr_hint = NULL;
00669 
00670   return err;
00671 }
00672 #endif /* LWIP_NETIF_HWADDRHINT*/
00673 
00674 #if IP_DEBUG
00675 /* Print an IP header by using LWIP_DEBUGF
00676  * @param p an IP packet, p->payload pointing to the IP header
00677  */
00678 void
00679 ip_debug_print(struct pbuf *p)
00680 {
00681   struct ip_hdr *iphdr = p->payload;
00682   u8_t *payload;
00683 
00684   payload = (u8_t *)iphdr + IP_HLEN;
00685 
00686   LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
00687   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00688   LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" |  0x%02"X16_F" |     %5"U16_F"     | (v, hl, tos, len)\n",
00689                     IPH_V(iphdr),
00690                     IPH_HL(iphdr),
00691                     IPH_TOS(iphdr),
00692                     ntohs(IPH_LEN(iphdr))));
00693   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00694   LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      |%"U16_F"%"U16_F"%"U16_F"|    %4"U16_F"   | (id, flags, offset)\n",
00695                     ntohs(IPH_ID(iphdr)),
00696                     ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
00697                     ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
00698                     ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
00699                     ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
00700   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00701   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |    0x%04"X16_F"     | (ttl, proto, chksum)\n",
00702                     IPH_TTL(iphdr),
00703                     IPH_PROTO(iphdr),
00704                     ntohs(IPH_CHKSUM(iphdr))));
00705   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00706   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (src)\n",
00707                     ip4_addr1(&iphdr->src),
00708                     ip4_addr2(&iphdr->src),
00709                     ip4_addr3(&iphdr->src),
00710                     ip4_addr4(&iphdr->src)));
00711   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00712   LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (dest)\n",
00713                     ip4_addr1(&iphdr->dest),
00714                     ip4_addr2(&iphdr->dest),
00715                     ip4_addr3(&iphdr->dest),
00716                     ip4_addr4(&iphdr->dest)));
00717   LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
00718 }
00719 #endif /* IP_DEBUG */