udp.c

00001 /**
00002  * @file
00003  * User Datagram Protocol module
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without modification,
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission.
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  *
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 
00039 
00040 /* udp.c
00041  *
00042  * The code for the User Datagram Protocol UDP & UDPLite (RFC 3828).
00043  *
00044  */
00045 
00046 /* @todo Check the use of '(struct udp_pcb).chksum_len_rx'!
00047  */
00048 
00049 #include "lwip/opt.h"
00050 
00051 #if LWIP_UDP /* don't build if not configured for use in lwipopts.h */
00052 
00053 #include "lwip/udp.h"
00054 #include "lwip/def.h"
00055 #include "lwip/memp.h"
00056 #include "lwip/inet.h"
00057 #include "lwip/inet_chksum.h"
00058 #include "lwip/ip_addr.h"
00059 #include "lwip/netif.h"
00060 #include "lwip/icmp.h"
00061 #include "lwip/stats.h"
00062 #include "lwip/snmp.h"
00063 #include "arch/perf.h"
00064 #include "lwip/dhcp.h "
00065 
00066 #include <string.h>
00067 
00068 /* The list of UDP PCBs */
00069 /* exported in udp.h (was static) */
00070 struct udp_pcb *udp_pcbs;
00071 
00072 /**
00073  * Process an incoming UDP datagram.
00074  *
00075  * Given an incoming UDP datagram (as a chain of pbufs) this function
00076  * finds a corresponding UDP PCB and hands over the pbuf to the pcbs
00077  * recv function. If no pcb is found or the datagram is incorrect, the
00078  * pbuf is freed.
00079  *
00080  * @param p pbuf to be demultiplexed to a UDP PCB.
00081  * @param inp network interface on which the datagram was received.
00082  *
00083  */
00084 void
00085 udp_input(struct pbuf *p, struct netif *inp)
00086 {
00087   struct udp_hdr *udphdr;
00088   struct udp_pcb *pcb, *prev;
00089   struct udp_pcb *uncon_pcb;
00090   struct ip_hdr *iphdr;
00091   u16_t src, dest;
00092   u8_t local_match;
00093   u8_t broadcast;
00094 
00095   PERF_START;
00096 
00097   UDP_STATS_INC(udp.recv);
00098 
00099   iphdr = (struct ip_hdr *)p->payload;
00100 
00101   /* Check minimum length (IP header + UDP header)
00102    * and move payload pointer to UDP header */
00103   if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
00104     /* drop short packets */
00105     LWIP_DEBUGF(UDP_DEBUG,
00106                 ("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
00107     UDP_STATS_INC(udp.lenerr);
00108     UDP_STATS_INC(udp.drop);
00109     snmp_inc_udpinerrors();
00110     pbuf_free(p);
00111     goto end;
00112   }
00113 
00114   udphdr = (struct udp_hdr *)p->payload;
00115 
00116   /* is broadcast packet ? */
00117   broadcast = ip_addr_isbroadcast(&(iphdr->dest), inp);
00118 
00119   LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));
00120 
00121   /* convert src and dest ports to host byte order */
00122   src = ntohs(udphdr->src);
00123   dest = ntohs(udphdr->dest);
00124 
00125   udp_debug_print(udphdr);
00126 
00127   /* print the UDP source and destination */
00128   LWIP_DEBUGF(UDP_DEBUG,
00129               ("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
00130                "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
00131                ip4_addr1(&iphdr->dest), ip4_addr2(&iphdr->dest),
00132                ip4_addr3(&iphdr->dest), ip4_addr4(&iphdr->dest), ntohs(udphdr->dest),
00133                ip4_addr1(&iphdr->src), ip4_addr2(&iphdr->src),
00134                ip4_addr3(&iphdr->src), ip4_addr4(&iphdr->src), ntohs(udphdr->src)));
00135 
00136 #if LWIP_DHCP
00137   pcb = NULL;
00138   /* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
00139      the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
00140   if (dest == DHCP_CLIENT_PORT) {
00141     /* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
00142     if (src == DHCP_SERVER_PORT) {
00143       if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
00144         /* accept the packe if 
00145            (- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
00146            - inp->dhcp->pcb->remote == ANY or iphdr->src */
00147         if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
00148            ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), &(iphdr->src)))) {
00149           pcb = inp->dhcp->pcb;
00150         }
00151       }
00152     }
00153   } else
00154 #endif /* LWIP_DHCP */
00155   {
00156     prev = NULL;
00157     local_match = 0;
00158     uncon_pcb = NULL;
00159     /* Iterate through the UDP pcb list for a matching pcb.
00160      * 'Perfect match' pcbs (connected to the remote port & ip address) are
00161      * preferred. If no perfect match is found, the first unconnected pcb that
00162      * matches the local port and ip address gets the datagram. */
00163     for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
00164       local_match = 0;
00165       /* print the PCB local and remote address */
00166       LWIP_DEBUGF(UDP_DEBUG,
00167                   ("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
00168                    "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
00169                    ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
00170                    ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
00171                    ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
00172                    ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip), pcb->remote_port));
00173 
00174       /* compare PCB local addr+port to UDP destination addr+port */
00175       if ((pcb->local_port == dest) &&
00176           ((!broadcast && ip_addr_isany(&pcb->local_ip)) ||
00177            ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)) ||
00178 #if LWIP_IGMP
00179            ip_addr_ismulticast(&(iphdr->dest)) ||
00180 #endif /* LWIP_IGMP */
00181 #if IP_SOF_BROADCAST_RECV
00182            (broadcast && (pcb->so_options & SOF_BROADCAST)))) {
00183 #else  /* IP_SOF_BROADCAST_RECV */
00184            (broadcast))) {
00185 #endif /* IP_SOF_BROADCAST_RECV */
00186         local_match = 1;
00187         if ((uncon_pcb == NULL) && 
00188             ((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
00189           /* the first unconnected matching PCB */
00190           uncon_pcb = pcb;
00191         }
00192       }
00193       /* compare PCB remote addr+port to UDP source addr+port */
00194       if ((local_match != 0) &&
00195           (pcb->remote_port == src) &&
00196           (ip_addr_isany(&pcb->remote_ip) ||
00197            ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)))) {
00198         /* the first fully matching PCB */
00199         if (prev != NULL) {
00200           /* move the pcb to the front of udp_pcbs so that is
00201              found faster next time */
00202           prev->next = pcb->next;
00203           pcb->next = udp_pcbs;
00204           udp_pcbs = pcb;
00205         } else {
00206           UDP_STATS_INC(udp.cachehit);
00207         }
00208         break;
00209       }
00210       prev = pcb;
00211     }
00212     /* no fully matching pcb found? then look for an unconnected pcb */
00213     if (pcb == NULL) {
00214       pcb = uncon_pcb;
00215     }
00216   }
00217 
00218   /* Check checksum if this is a match or if it was directed at us. */
00219   if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, &iphdr->dest)) {
00220     LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
00221 #if LWIP_UDPLITE
00222     if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
00223       /* Do the UDP Lite checksum */
00224 #if CHECKSUM_CHECK_UDP
00225       u16_t chklen = ntohs(udphdr->len);
00226       if (chklen < sizeof(struct udp_hdr)) {
00227         if (chklen == 0) {
00228           /* For UDP-Lite, checksum length of 0 means checksum
00229              over the complete packet (See RFC 3828 chap. 3.1) */
00230           chklen = p->tot_len;
00231         } else {
00232           /* At least the UDP-Lite header must be covered by the
00233              checksum! (Again, see RFC 3828 chap. 3.1) */
00234           UDP_STATS_INC(udp.chkerr);
00235           UDP_STATS_INC(udp.drop);
00236           snmp_inc_udpinerrors();
00237           pbuf_free(p);
00238           goto end;
00239         }
00240       }
00241       if (inet_chksum_pseudo_partial(p, (struct ip_addr *)&(iphdr->src),
00242                              (struct ip_addr *)&(iphdr->dest),
00243                              IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
00244         LWIP_DEBUGF(UDP_DEBUG | 2,
00245                     ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
00246         UDP_STATS_INC(udp.chkerr);
00247         UDP_STATS_INC(udp.drop);
00248         snmp_inc_udpinerrors();
00249         pbuf_free(p);
00250         goto end;
00251       }
00252 #endif /* CHECKSUM_CHECK_UDP */
00253     } else
00254 #endif /* LWIP_UDPLITE */
00255     {
00256 #if CHECKSUM_CHECK_UDP
00257       if (udphdr->chksum != 0) {
00258         if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
00259                                (struct ip_addr *)&(iphdr->dest),
00260                                IP_PROTO_UDP, p->tot_len) != 0) {
00261           LWIP_DEBUGF(UDP_DEBUG | 2,
00262                       ("udp_input: UDP datagram discarded due to failing checksum\n"));
00263           UDP_STATS_INC(udp.chkerr);
00264           UDP_STATS_INC(udp.drop);
00265           snmp_inc_udpinerrors();
00266           pbuf_free(p);
00267           goto end;
00268         }
00269       }
00270 #endif /* CHECKSUM_CHECK_UDP */
00271     }
00272     if(pbuf_header(p, -UDP_HLEN)) {
00273       /* Can we cope with this failing? Just assert for now */
00274       LWIP_ASSERT("pbuf_header failed\n", 0);
00275       UDP_STATS_INC(udp.drop);
00276       snmp_inc_udpinerrors();
00277       pbuf_free(p);
00278       goto end;
00279     }
00280     if (pcb != NULL) {
00281       snmp_inc_udpindatagrams();
00282       /* callback */
00283       if (pcb->recv != NULL) {
00284         /* now the recv function is responsible for freeing p */
00285         pcb->recv(pcb->recv_arg, pcb, p, &iphdr->src, src);
00286       } else {
00287         /* no recv function registered? then we have to free the pbuf! */
00288         pbuf_free(p);
00289         goto end;
00290       }
00291     } else {
00292       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: not for us.\n"));
00293 
00294 #if LWIP_ICMP
00295       /* No match was found, send ICMP destination port unreachable unless
00296          destination address was broadcast/multicast. */
00297       if (!broadcast &&
00298           !ip_addr_ismulticast(&iphdr->dest)) {
00299         /* move payload pointer back to ip header */
00300         pbuf_header(p, (IPH_HL(iphdr) * 4) + UDP_HLEN);
00301         LWIP_ASSERT("p->payload == iphdr", (p->payload == iphdr));
00302         icmp_dest_unreach(p, ICMP_DUR_PORT);
00303       }
00304 #endif /* LWIP_ICMP */
00305       UDP_STATS_INC(udp.proterr);
00306       UDP_STATS_INC(udp.drop);
00307       snmp_inc_udpnoports();
00308       pbuf_free(p);
00309     }
00310   } else {
00311     pbuf_free(p);
00312   }
00313 end:
00314   PERF_STOP("udp_input");
00315 }
00316 
00317 /**
00318  * Send data using UDP.
00319  *
00320  * @param pcb UDP PCB used to send the data.
00321  * @param p chain of pbuf's to be sent.
00322  *
00323  * The datagram will be sent to the current remote_ip & remote_port
00324  * stored in pcb. If the pcb is not bound to a port, it will
00325  * automatically be bound to a random port.
00326  *
00327  * @return lwIP error code.
00328  * - ERR_OK. Successful. No error occured.
00329  * - ERR_MEM. Out of memory.
00330  * - ERR_RTE. Could not find route to destination address.
00331  * - More errors could be returned by lower protocol layers.
00332  *
00333  * @see udp_disconnect() udp_sendto()
00334  */
00335 err_t
00336 udp_send(struct udp_pcb *pcb, struct pbuf *p)
00337 {
00338   /* send to the packet using remote ip and port stored in the pcb */
00339   return udp_sendto(pcb, p, &pcb->remote_ip, pcb->remote_port);
00340 }
00341 
00342 /**
00343  * Send data to a specified address using UDP.
00344  *
00345  * @param pcb UDP PCB used to send the data.
00346  * @param p chain of pbuf's to be sent.
00347  * @param dst_ip Destination IP address.
00348  * @param dst_port Destination UDP port.
00349  *
00350  * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
00351  *
00352  * If the PCB already has a remote address association, it will
00353  * be restored after the data is sent.
00354  * 
00355  * @return lwIP error code (@see udp_send for possible error codes)
00356  *
00357  * @see udp_disconnect() udp_send()
00358  */
00359 err_t
00360 udp_sendto(struct udp_pcb *pcb, struct pbuf *p,
00361   struct ip_addr *dst_ip, u16_t dst_port)
00362 {
00363   struct netif *netif;
00364 
00365   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | 3, ("udp_send\n"));
00366 
00367   /* find the outgoing network interface for this packet */
00368 #if LWIP_IGMP
00369   netif = ip_route((ip_addr_ismulticast(dst_ip))?(&(pcb->multicast_ip)):(dst_ip));
00370 #else
00371   netif = ip_route(dst_ip);
00372 #endif /* LWIP_IGMP */
00373 
00374   /* no outgoing network interface could be found? */
00375   if (netif == NULL) {
00376     LWIP_DEBUGF(UDP_DEBUG | 1, ("udp_send: No route to 0x%"X32_F"\n", dst_ip->addr));
00377     UDP_STATS_INC(udp.rterr);
00378     return ERR_RTE;
00379   }
00380   return udp_sendto_if(pcb, p, dst_ip, dst_port, netif);
00381 }
00382 
00383 /**
00384  * Send data to a specified address using UDP.
00385  * The netif used for sending can be specified.
00386  *
00387  * This function exists mainly for DHCP, to be able to send UDP packets
00388  * on a netif that is still down.
00389  *
00390  * @param pcb UDP PCB used to send the data.
00391  * @param p chain of pbuf's to be sent.
00392  * @param dst_ip Destination IP address.
00393  * @param dst_port Destination UDP port.
00394  * @param netif the netif used for sending.
00395  *
00396  * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
00397  *
00398  * @return lwIP error code (@see udp_send for possible error codes)
00399  *
00400  * @see udp_disconnect() udp_send()
00401  */
00402 err_t
00403 udp_sendto_if(struct udp_pcb *pcb, struct pbuf *p,
00404   struct ip_addr *dst_ip, u16_t dst_port, struct netif *netif)
00405 {
00406   struct udp_hdr *udphdr;
00407   struct ip_addr *src_ip;
00408   err_t err;
00409   struct pbuf *q; /* q will be sent down the stack */
00410 
00411 #if IP_SOF_BROADCAST
00412   /* broadcast filter? */
00413   if ( ((pcb->so_options & SOF_BROADCAST) == 0) && ip_addr_isbroadcast(dst_ip, netif) ) {
00414     LWIP_DEBUGF(UDP_DEBUG | 1, ("udp_sendto_if: SOF_BROADCAST not enabled on pcb %p\n", (void *)pcb));
00415     return ERR_VAL;
00416   }
00417 #endif /* IP_SOF_BROADCAST */
00418 
00419   /* if the PCB is not yet bound to a port, bind it here */
00420   if (pcb->local_port == 0) {
00421     LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | 2, ("udp_send: not yet bound to a port, binding now\n"));
00422     err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);
00423     if (err != ERR_OK) {
00424       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | 2, ("udp_send: forced port bind failed\n"));
00425       return err;
00426     }
00427   }
00428 
00429   /* not enough space to add an UDP header to first pbuf in given p chain? */
00430   if (pbuf_header(p, UDP_HLEN)) {
00431     /* allocate header in a separate new pbuf */
00432     q = pbuf_alloc(PBUF_IP, UDP_HLEN, PBUF_RAM);
00433     /* new header pbuf could not be allocated? */
00434     if (q == NULL) {
00435       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | 2, ("udp_send: could not allocate header\n"));
00436       return ERR_MEM;
00437     }
00438     /* chain header q in front of given pbuf p */
00439     pbuf_chain(q, p);
00440     /* first pbuf q points to header pbuf */
00441     LWIP_DEBUGF(UDP_DEBUG,
00442                 ("udp_send: added header pbuf %p before given pbuf %p\n", (void *)q, (void *)p));
00443   } else {
00444     /* adding space for header within p succeeded */
00445     /* first pbuf q equals given pbuf */
00446     q = p;
00447     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: added header in given pbuf %p\n", (void *)p));
00448   }
00449   LWIP_ASSERT("check that first pbuf can hold struct udp_hdr",
00450               (q->len >= sizeof(struct udp_hdr)));
00451   /* q now represents the packet to be sent */
00452   udphdr = (struct udp_hdr *)q->payload;
00453   udphdr->src = htons(pcb->local_port);
00454   udphdr->dest = htons(dst_port);
00455   /* in UDP, 0 checksum means 'no checksum' */
00456   udphdr->chksum = 0x0000; 
00457 
00458   /* PCB local address is IP_ANY_ADDR? */
00459   if (ip_addr_isany(&pcb->local_ip)) {
00460     /* use outgoing network interface IP address as source address */
00461     src_ip = &(netif->ip_addr);
00462   } else {
00463     /* check if UDP PCB local IP address is correct
00464      * this could be an old address if netif->ip_addr has changed */
00465     if (!ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) {
00466       /* local_ip doesn't match, drop the packet */
00467       if (q != p) {
00468         /* free the header pbuf */
00469         pbuf_free(q);
00470         q = NULL;
00471         /* p is still referenced by the caller, and will live on */
00472       }
00473       return ERR_VAL;
00474     }
00475     /* use UDP PCB local IP address as source address */
00476     src_ip = &(pcb->local_ip);
00477   }
00478 
00479   LWIP_DEBUGF(UDP_DEBUG, ("udp_send: sending datagram of length %"U16_F"\n", q->tot_len));
00480 
00481 #if LWIP_UDPLITE
00482   /* UDP Lite protocol? */
00483   if (pcb->flags & UDP_FLAGS_UDPLITE) {
00484     u16_t chklen, chklen_hdr;
00485     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE packet length %"U16_F"\n", q->tot_len));
00486     /* set UDP message length in UDP header */
00487     chklen_hdr = chklen = pcb->chksum_len_tx;
00488     if ((chklen < sizeof(struct udp_hdr)) || (chklen > q->tot_len)) {
00489       if (chklen != 0) {
00490         LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE pcb->chksum_len is illegal: %"U16_F"\n", chklen));
00491       }
00492       /* For UDP-Lite, checksum length of 0 means checksum
00493          over the complete packet. (See RFC 3828 chap. 3.1)
00494          At least the UDP-Lite header must be covered by the
00495          checksum, therefore, if chksum_len has an illegal
00496          value, we generate the checksum over the complete
00497          packet to be safe. */
00498       chklen_hdr = 0;
00499       chklen = q->tot_len;
00500     }
00501     udphdr->len = htons(chklen_hdr);
00502     /* calculate checksum */
00503 #if CHECKSUM_GEN_UDP
00504     udphdr->chksum = inet_chksum_pseudo_partial(q, src_ip, dst_ip,
00505                                         IP_PROTO_UDPLITE, q->tot_len, chklen);
00506     /* chksum zero must become 0xffff, as zero means 'no checksum' */
00507     if (udphdr->chksum == 0x0000)
00508       udphdr->chksum = 0xffff;
00509 #endif /* CHECKSUM_CHECK_UDP */
00510     /* output to IP */
00511     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDPLITE,)\n"));
00512 #if LWIP_NETIF_HWADDRHINT
00513     netif->addr_hint = &(pcb->addr_hint);
00514 #endif /* LWIP_NETIF_HWADDRHINT*/
00515     err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDPLITE, netif);
00516 #if LWIP_NETIF_HWADDRHINT
00517     netif->addr_hint = NULL;
00518 #endif /* LWIP_NETIF_HWADDRHINT*/
00519   } else
00520 #endif /* LWIP_UDPLITE */
00521   {      /* UDP */
00522     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP packet length %"U16_F"\n", q->tot_len));
00523     udphdr->len = htons(q->tot_len);
00524     /* calculate checksum */
00525 #if CHECKSUM_GEN_UDP
00526     if ((pcb->flags & UDP_FLAGS_NOCHKSUM) == 0) {
00527       udphdr->chksum = inet_chksum_pseudo(q, src_ip, dst_ip, IP_PROTO_UDP, q->tot_len);
00528       /* chksum zero must become 0xffff, as zero means 'no checksum' */
00529       if (udphdr->chksum == 0x0000) udphdr->chksum = 0xffff;
00530     }
00531 #endif /* CHECKSUM_CHECK_UDP */
00532     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04"X16_F"\n", udphdr->chksum));
00533     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDP,)\n"));
00534     /* output to IP */
00535 #if LWIP_NETIF_HWADDRHINT
00536     netif->addr_hint = &(pcb->addr_hint);
00537 #endif /* LWIP_NETIF_HWADDRHINT*/
00538     err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDP, netif);
00539 #if LWIP_NETIF_HWADDRHINT
00540     netif->addr_hint = NULL;
00541 #endif /* LWIP_NETIF_HWADDRHINT*/
00542   }
00543   /* TODO: must this be increased even if error occured? */
00544   snmp_inc_udpoutdatagrams();
00545 
00546   /* did we chain a separate header pbuf earlier? */
00547   if (q != p) {
00548     /* free the header pbuf */
00549     pbuf_free(q);
00550     q = NULL;
00551     /* p is still referenced by the caller, and will live on */
00552   }
00553 
00554   UDP_STATS_INC(udp.xmit);
00555   return err;
00556 }
00557 
00558 /**
00559  * Bind an UDP PCB.
00560  *
00561  * @param pcb UDP PCB to be bound with a local address ipaddr and port.
00562  * @param ipaddr local IP address to bind with. Use IP_ADDR_ANY to
00563  * bind to all local interfaces.
00564  * @param port local UDP port to bind with. Use 0 to automatically bind
00565  * to a random port between UDP_LOCAL_PORT_RANGE_START and
00566  * UDP_LOCAL_PORT_RANGE_END.
00567  *
00568  * ipaddr & port are expected to be in the same byte order as in the pcb.
00569  *
00570  * @return lwIP error code.
00571  * - ERR_OK. Successful. No error occured.
00572  * - ERR_USE. The specified ipaddr and port are already bound to by
00573  * another UDP PCB.
00574  *
00575  * @see udp_disconnect()
00576  */
00577 err_t
00578 udp_bind(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
00579 {
00580   struct udp_pcb *ipcb;
00581   u8_t rebind;
00582 
00583   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | 3, ("udp_bind(ipaddr = "));
00584   ip_addr_debug_print(UDP_DEBUG, ipaddr);
00585   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | 3, (", port = %"U16_F")\n", port));
00586 
00587   rebind = 0;
00588   /* Check for double bind and rebind of the same pcb */
00589   for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
00590     /* is this UDP PCB already on active list? */
00591     if (pcb == ipcb) {
00592       /* pcb may occur at most once in active list */
00593       LWIP_ASSERT("rebind == 0", rebind == 0);
00594       /* pcb already in list, just rebind */
00595       rebind = 1;
00596     }
00597 
00598     /* this code does not allow upper layer to share a UDP port for
00599        listening to broadcast or multicast traffic (See SO_REUSE_ADDR and
00600        SO_REUSE_PORT under *BSD). TODO: See where it fits instead, OR
00601        combine with implementation of UDP PCB flags. Leon Woestenberg. */
00602 #ifdef LWIP_UDP_TODO
00603     /* port matches that of PCB in list? */
00604     else
00605       if ((ipcb->local_port == port) &&
00606           /* IP address matches, or one is IP_ADDR_ANY? */
00607           (ip_addr_isany(&(ipcb->local_ip)) ||
00608            ip_addr_isany(ipaddr) ||
00609            ip_addr_cmp(&(ipcb->local_ip), ipaddr))) {
00610         /* other PCB already binds to this local IP and port */
00611         LWIP_DEBUGF(UDP_DEBUG,
00612                     ("udp_bind: local port %"U16_F" already bound by another pcb\n", port));
00613         return ERR_USE;
00614       }
00615 #endif
00616   }
00617 
00618   ip_addr_set(&pcb->local_ip, ipaddr);
00619 
00620   /* no port specified? */
00621   if (port == 0) {
00622 #ifndef UDP_LOCAL_PORT_RANGE_START
00623 #define UDP_LOCAL_PORT_RANGE_START 4096
00624 #define UDP_LOCAL_PORT_RANGE_END   0x7fff
00625 #endif
00626     port = UDP_LOCAL_PORT_RANGE_START;
00627     ipcb = udp_pcbs;
00628     while ((ipcb != NULL) && (port != UDP_LOCAL_PORT_RANGE_END)) {
00629       if (ipcb->local_port == port) {
00630         /* port is already used by another udp_pcb */
00631         port++;
00632         /* restart scanning all udp pcbs */
00633         ipcb = udp_pcbs;
00634       } else
00635         /* go on with next udp pcb */
00636         ipcb = ipcb->next;
00637     }
00638     if (ipcb != NULL) {
00639       /* no more ports available in local range */
00640       LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: out of free UDP ports\n"));
00641       return ERR_USE;
00642     }
00643   }
00644   pcb->local_port = port;
00645   snmp_insert_udpidx_tree(pcb);
00646   /* pcb not active yet? */
00647   if (rebind == 0) {
00648     /* place the PCB on the active list if not already there */
00649     pcb->next = udp_pcbs;
00650     udp_pcbs = pcb;
00651   }
00652   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
00653               ("udp_bind: bound to %"U16_F".%"U16_F".%"U16_F".%"U16_F", port %"U16_F"\n",
00654                (u16_t)((ntohl(pcb->local_ip.addr) >> 24) & 0xff),
00655                (u16_t)((ntohl(pcb->local_ip.addr) >> 16) & 0xff),
00656                (u16_t)((ntohl(pcb->local_ip.addr) >> 8) & 0xff),
00657                (u16_t)(ntohl(pcb->local_ip.addr) & 0xff), pcb->local_port));
00658   return ERR_OK;
00659 }
00660 /**
00661  * Connect an UDP PCB.
00662  *
00663  * This will associate the UDP PCB with the remote address.
00664  *
00665  * @param pcb UDP PCB to be connected with remote address ipaddr and port.
00666  * @param ipaddr remote IP address to connect with.
00667  * @param port remote UDP port to connect with.
00668  *
00669  * @return lwIP error code
00670  *
00671  * ipaddr & port are expected to be in the same byte order as in the pcb.
00672  *
00673  * The udp pcb is bound to a random local port if not already bound.
00674  *
00675  * @see udp_disconnect()
00676  */
00677 err_t
00678 udp_connect(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
00679 {
00680   struct udp_pcb *ipcb;
00681 
00682   if (pcb->local_port == 0) {
00683     err_t err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);
00684     if (err != ERR_OK)
00685       return err;
00686   }
00687 
00688   ip_addr_set(&pcb->remote_ip, ipaddr);
00689   pcb->remote_port = port;
00690   pcb->flags |= UDP_FLAGS_CONNECTED;
00691 /** TODO: this functionality belongs in upper layers */
00692 #ifdef LWIP_UDP_TODO
00693   /* Nail down local IP for netconn_addr()/getsockname() */
00694   if (ip_addr_isany(&pcb->local_ip) && !ip_addr_isany(&pcb->remote_ip)) {
00695     struct netif *netif;
00696 
00697     if ((netif = ip_route(&(pcb->remote_ip))) == NULL) {
00698       LWIP_DEBUGF(UDP_DEBUG, ("udp_connect: No route to 0x%lx\n", pcb->remote_ip.addr));
00699       UDP_STATS_INC(udp.rterr);
00700       return ERR_RTE;
00701     }
00702     /** TODO: this will bind the udp pcb locally, to the interface which
00703         is used to route output packets to the remote address. However, we
00704         might want to accept incoming packets on any interface! */
00705     pcb->local_ip = netif->ip_addr;
00706   } else if (ip_addr_isany(&pcb->remote_ip)) {
00707     pcb->local_ip.addr = 0;
00708   }
00709 #endif
00710   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
00711               ("udp_connect: connected to %"U16_F".%"U16_F".%"U16_F".%"U16_F",port %"U16_F"\n",
00712                (u16_t)((ntohl(pcb->remote_ip.addr) >> 24) & 0xff),
00713                (u16_t)((ntohl(pcb->remote_ip.addr) >> 16) & 0xff),
00714                (u16_t)((ntohl(pcb->remote_ip.addr) >> 8) & 0xff),
00715                (u16_t)(ntohl(pcb->remote_ip.addr) & 0xff), pcb->remote_port));
00716 
00717   /* Insert UDP PCB into the list of active UDP PCBs. */
00718   for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
00719     if (pcb == ipcb) {
00720       /* already on the list, just return */
00721       return ERR_OK;
00722     }
00723   }
00724   /* PCB not yet on the list, add PCB now */
00725   pcb->next = udp_pcbs;
00726   udp_pcbs = pcb;
00727   return ERR_OK;
00728 }
00729 
00730 /**
00731  * Disconnect a UDP PCB
00732  *
00733  * @param pcb the udp pcb to disconnect.
00734  */
00735 void
00736 udp_disconnect(struct udp_pcb *pcb)
00737 {
00738   /* reset remote address association */
00739   ip_addr_set(&pcb->remote_ip, IP_ADDR_ANY);
00740   pcb->remote_port = 0;
00741   /* mark PCB as unconnected */
00742   pcb->flags &= ~UDP_FLAGS_CONNECTED;
00743 }
00744 
00745 /**
00746  * Set a receive callback for a UDP PCB
00747  *
00748  * This callback will be called when receiving a datagram for the pcb.
00749  *
00750  * @param pcb the pcb for wich to set the recv callback
00751  * @param recv function pointer of the callback function
00752  * @param recv_arg additional argument to pass to the callback function
00753  */
00754 void
00755 udp_recv(struct udp_pcb *pcb,
00756          void (* recv)(void *arg, struct udp_pcb *upcb, struct pbuf *p,
00757                        struct ip_addr *addr, u16_t port),
00758          void *recv_arg)
00759 {
00760   /* remember recv() callback and user data */
00761   pcb->recv = recv;
00762   pcb->recv_arg = recv_arg;
00763 }
00764 
00765 /**
00766  * Remove an UDP PCB.
00767  *
00768  * @param pcb UDP PCB to be removed. The PCB is removed from the list of
00769  * UDP PCB's and the data structure is freed from memory.
00770  *
00771  * @see udp_new()
00772  */
00773 void
00774 udp_remove(struct udp_pcb *pcb)
00775 {
00776   struct udp_pcb *pcb2;
00777 
00778   snmp_delete_udpidx_tree(pcb);
00779   /* pcb to be removed is first in list? */
00780   if (udp_pcbs == pcb) {
00781     /* make list start at 2nd pcb */
00782     udp_pcbs = udp_pcbs->next;
00783     /* pcb not 1st in list */
00784   } else
00785     for (pcb2 = udp_pcbs; pcb2 != NULL; pcb2 = pcb2->next) {
00786       /* find pcb in udp_pcbs list */
00787       if (pcb2->next != NULL && pcb2->next == pcb) {
00788         /* remove pcb from list */
00789         pcb2->next = pcb->next;
00790       }
00791     }
00792   memp_free(MEMP_UDP_PCB, pcb);
00793 }
00794 
00795 /**
00796  * Create a UDP PCB.
00797  *
00798  * @return The UDP PCB which was created. NULL if the PCB data structure
00799  * could not be allocated.
00800  *
00801  * @see udp_remove()
00802  */
00803 struct udp_pcb *
00804 udp_new(void)
00805 {
00806   struct udp_pcb *pcb;
00807   pcb = (struct udp_pcb *)memp_malloc(MEMP_UDP_PCB);
00808   /* could allocate UDP PCB? */
00809   if (pcb != NULL) {
00810     /* UDP Lite: by initializing to all zeroes, chksum_len is set to 0
00811      * which means checksum is generated over the whole datagram per default
00812      * (recommended as default by RFC 3828). */
00813     /* initialize PCB to all zeroes */
00814     memset(pcb, 0, sizeof(struct udp_pcb));
00815     pcb->ttl = UDP_TTL;
00816   }
00817   return pcb;
00818 }
00819 
00820 #if UDP_DEBUG
00821 /**
00822  * Print UDP header information for debug purposes.
00823  *
00824  * @param udphdr pointer to the udp header in memory.
00825  */
00826 void
00827 udp_debug_print(struct udp_hdr *udphdr)
00828 {
00829   LWIP_DEBUGF(UDP_DEBUG, ("UDP header:\n"));
00830   LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
00831   LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     %5"U16_F"     | (src port, dest port)\n",
00832                           ntohs(udphdr->src), ntohs(udphdr->dest)));
00833   LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
00834   LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     0x%04"X16_F"    | (len, chksum)\n",
00835                           ntohs(udphdr->len), ntohs(udphdr->chksum)));
00836   LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
00837 }
00838 #endif /* UDP_DEBUG */
00839 
00840 #endif /* LWIP_UDP */