lib/drivers/lwip/src/core/udp.c

   1 /**
   2  * @file
   3  * User Datagram Protocol module
   4  *
   5  */
   6
   7 /*
   8  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without modification,
  12  * are permitted provided that the following conditions are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright notice,
  15  *    this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright notice,
  17  *    this list of conditions and the following disclaimer in the documentation
  18  *    and/or other materials provided with the distribution.
  19  * 3. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  23  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  24  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  25  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  27  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  31  * OF SUCH DAMAGE.
  32  *
  33  * This file is part of the lwIP TCP/IP stack.
  34  *
  35  * Author: Adam Dunkels <adam@sics.se>
  36  *
  37  */
  38
  39
  40 /* udp.c
  41  *
  42  * The code for the User Datagram Protocol UDP & UDPLite (RFC 3828).
  43  *
  44  */
  45
  46 /* @todo Check the use of '(struct udp_pcb).chksum_len_rx'!
  47  */
  48
  49 #include "lwip/opt.h"
  50
  51 #if LWIP_UDP /* don't build if not configured for use in lwipopts.h */
  52
  53 #include "lwip/udp.h"
  54 #include "lwip/def.h"
  55 #include "lwip/memp.h"
  56 #include "lwip/inet.h"
  57 #include "lwip/inet_chksum.h"
  58 #include "lwip/ip_addr.h"
  59 #include "lwip/netif.h"
  60 #include "lwip/icmp.h"
  61 #include "lwip/stats.h"
  62 #include "lwip/snmp.h"
  63 #include "arch/perf.h"
  64 #include "lwip/dhcp.h"
  65
  66 #include <string.h>
  67
  68 /* The list of UDP PCBs */
  69 /* exported in udp.h (was static) */
  70 struct udp_pcb *udp_pcbs;
  71
  72 /**
  73  * Process an incoming UDP datagram.
  74  *
  75  * Given an incoming UDP datagram (as a chain of pbufs) this function
  76  * finds a corresponding UDP PCB and hands over the pbuf to the pcbs
  77  * recv function. If no pcb is found or the datagram is incorrect, the
  78  * pbuf is freed.
  79  *
  80  * @param p pbuf to be demultiplexed to a UDP PCB.
  81  * @param inp network interface on which the datagram was received.
  82  *
  83  */
  84 void
  85 udp_input(struct pbuf *p, struct netif *inp)
  86 {
  87   struct udp_hdr *udphdr;
  88   struct udp_pcb *pcb, *prev;
  89   struct udp_pcb *uncon_pcb;
  90   struct ip_hdr *iphdr;
  91   u16_t src, dest;
  92   u8_t local_match;
  93   u8_t broadcast;
  94
  95   PERF_START;
  96
  97   UDP_STATS_INC(udp.recv);
  98
  99   iphdr = p->payload;
 100
 101   /* Check minimum length (IP header + UDP header)
 102    * and move payload pointer to UDP header */
 103   if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
 104     /* drop short packets */
 105     LWIP_DEBUGF(UDP_DEBUG,
 106                 ("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
 107     UDP_STATS_INC(udp.lenerr);
 108     UDP_STATS_INC(udp.drop);
 109     snmp_inc_udpinerrors();
 110     pbuf_free(p);
 111     goto end;
 112   }
 113
 114   udphdr = (struct udp_hdr *)p->payload;
 115
 116   /* is broadcast packet ? */
 117   broadcast = ip_addr_isbroadcast(&(iphdr->dest), inp);
 118
 119   LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));
 120
 121   /* convert src and dest ports to host byte order */
 122   src = ntohs(udphdr->src);
 123   dest = ntohs(udphdr->dest);
 124
 125   udp_debug_print(udphdr);
 126
 127   /* print the UDP source and destination */
 128   LWIP_DEBUGF(UDP_DEBUG,
 129               ("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
 130                "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
 131                ip4_addr1(&iphdr->dest), ip4_addr2(&iphdr->dest),
 132                ip4_addr3(&iphdr->dest), ip4_addr4(&iphdr->dest), ntohs(udphdr->dest),
 133                ip4_addr1(&iphdr->src), ip4_addr2(&iphdr->src),
 134                ip4_addr3(&iphdr->src), ip4_addr4(&iphdr->src), ntohs(udphdr->src)));
 135
 136 #if LWIP_DHCP
 137   pcb = NULL;
 138   /* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
 139      the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
 140   if (dest == DHCP_CLIENT_PORT) {
 141     /* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
 142     if (src == DHCP_SERVER_PORT) {
 143       if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
 144         /* accept the packe if
 145            (- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
 146            - inp->dhcp->pcb->remote == ANY or iphdr->src */
 147         if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
 148            ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), &(iphdr->src)))) {
 149           pcb = inp->dhcp->pcb;
 150         }
 151       }
 152     }
 153   } else
 154 #endif /* LWIP_DHCP */
 155   {
 156     prev = NULL;
 157     local_match = 0;
 158     uncon_pcb = NULL;
 159     /* Iterate through the UDP pcb list for a matching pcb.
 160      * 'Perfect match' pcbs (connected to the remote port & ip address) are
 161      * preferred. If no perfect match is found, the first unconnected pcb that
 162      * matches the local port and ip address gets the datagram. */
 163     for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
 164       local_match = 0;
 165       /* print the PCB local and remote address */
 166       LWIP_DEBUGF(UDP_DEBUG,
 167                   ("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
 168                    "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
 169                    ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
 170                    ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
 171                    ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
 172                    ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip), pcb->remote_port));
 173
 174       /* compare PCB local addr+port to UDP destination addr+port */
 175       if ((pcb->local_port == dest) &&
 176           ((!broadcast && ip_addr_isany(&pcb->local_ip)) ||
 177            ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)) ||
 178 #if LWIP_IGMP
 179            ip_addr_ismulticast(&(iphdr->dest)) ||
 180 #endif /* LWIP_IGMP */
 181 #if IP_SOF_BROADCAST_RECV
 182            (broadcast && (pcb->so_options & SOF_BROADCAST)))) {
 183 #else  /* IP_SOF_BROADCAST_RECV */
 184            (broadcast))) {
 185 #endif /* IP_SOF_BROADCAST_RECV */
 186         local_match = 1;
 187         if ((uncon_pcb == NULL) &&
 188             ((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
 189           /* the first unconnected matching PCB */
 190           uncon_pcb = pcb;
 191         }
 192       }
 193       /* compare PCB remote addr+port to UDP source addr+port */
 194       if ((local_match != 0) &&
 195           (pcb->remote_port == src) &&
 196           (ip_addr_isany(&pcb->remote_ip) ||
 197            ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)))) {
 198         /* the first fully matching PCB */
 199         if (prev != NULL) {
 200           /* move the pcb to the front of udp_pcbs so that is
 201              found faster next time */
 202           prev->next = pcb->next;
 203           pcb->next = udp_pcbs;
 204           udp_pcbs = pcb;
 205         } else {
 206           UDP_STATS_INC(udp.cachehit);
 207         }
 208         break;
 209       }
 210       prev = pcb;
 211     }
 212     /* no fully matching pcb found? then look for an unconnected pcb */
 213     if (pcb == NULL) {
 214       pcb = uncon_pcb;
 215     }
 216   }
 217
 218   /* Check checksum if this is a match or if it was directed at us. */
 219   if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, &iphdr->dest)) {
 220     LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
 221 #if LWIP_UDPLITE
 222     if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
 223       /* Do the UDP Lite checksum */
 224 #if CHECKSUM_CHECK_UDP
 225       u16_t chklen = ntohs(udphdr->len);
 226       if (chklen < sizeof(struct udp_hdr)) {
 227         if (chklen == 0) {
 228           /* For UDP-Lite, checksum length of 0 means checksum
 229              over the complete packet (See RFC 3828 chap. 3.1) */
 230           chklen = p->tot_len;
 231         } else {
 232           /* At least the UDP-Lite header must be covered by the
 233              checksum! (Again, see RFC 3828 chap. 3.1) */
 234           UDP_STATS_INC(udp.chkerr);
 235           UDP_STATS_INC(udp.drop);
 236           snmp_inc_udpinerrors();
 237           pbuf_free(p);
 238           goto end;
 239         }
 240       }
 241       if (inet_chksum_pseudo_partial(p, (struct ip_addr *)&(iphdr->src),
 242                              (struct ip_addr *)&(iphdr->dest),
 243                              IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
 244        LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
 245                    ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
 246         UDP_STATS_INC(udp.chkerr);
 247         UDP_STATS_INC(udp.drop);
 248         snmp_inc_udpinerrors();
 249         pbuf_free(p);
 250         goto end;
 251       }
 252 #endif /* CHECKSUM_CHECK_UDP */
 253     } else
 254 #endif /* LWIP_UDPLITE */
 255     {
 256 #if CHECKSUM_CHECK_UDP
 257       if (udphdr->chksum != 0) {
 258         if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
 259                                (struct ip_addr *)&(iphdr->dest),
 260                                IP_PROTO_UDP, p->tot_len) != 0) {
 261           LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
 262                       ("udp_input: UDP datagram discarded due to failing checksum\n"));
 263           UDP_STATS_INC(udp.chkerr);
 264           UDP_STATS_INC(udp.drop);
 265           snmp_inc_udpinerrors();
 266           pbuf_free(p);
 267           goto end;
 268         }
 269       }
 270 #endif /* CHECKSUM_CHECK_UDP */
 271     }
 272     if(pbuf_header(p, -UDP_HLEN)) {
 273       /* Can we cope with this failing? Just assert for now */
 274       LWIP_ASSERT("pbuf_header failed\n", 0);
 275       UDP_STATS_INC(udp.drop);
 276       snmp_inc_udpinerrors();
 277       pbuf_free(p);
 278       goto end;
 279     }
 280     if (pcb != NULL) {
 281       snmp_inc_udpindatagrams();
 282       /* callback */
 283       if (pcb->recv != NULL) {
 284         /* now the recv function is responsible for freeing p */
 285         pcb->recv(pcb->recv_arg, pcb, p, &iphdr->src, src);
 286       } else {
 287         /* no recv function registered? then we have to free the pbuf! */
 288         pbuf_free(p);
 289         goto end;
 290       }
 291     } else {
 292       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: not for us.\n"));
 293
 294 #if LWIP_ICMP
 295       /* No match was found, send ICMP destination port unreachable unless
 296          destination address was broadcast/multicast. */
 297       if (!broadcast &&
 298           !ip_addr_ismulticast(&iphdr->dest)) {
 299         /* move payload pointer back to ip header */
 300         pbuf_header(p, (IPH_HL(iphdr) * 4) + UDP_HLEN);
 301         LWIP_ASSERT("p->payload == iphdr", (p->payload == iphdr));
 302         icmp_dest_unreach(p, ICMP_DUR_PORT);
 303       }
 304 #endif /* LWIP_ICMP */
 305       UDP_STATS_INC(udp.proterr);
 306       UDP_STATS_INC(udp.drop);
 307       snmp_inc_udpnoports();
 308       pbuf_free(p);
 309     }
 310   } else {
 311     pbuf_free(p);
 312   }
 313 end:
 314   PERF_STOP("udp_input");
 315 }
 316
 317 /**
 318  * Send data using UDP.
 319  *
 320  * @param pcb UDP PCB used to send the data.
 321  * @param p chain of pbuf's to be sent.
 322  *
 323  * The datagram will be sent to the current remote_ip & remote_port
 324  * stored in pcb. If the pcb is not bound to a port, it will
 325  * automatically be bound to a random port.
 326  *
 327  * @return lwIP error code.
 328  * - ERR_OK. Successful. No error occured.
 329  * - ERR_MEM. Out of memory.
 330  * - ERR_RTE. Could not find route to destination address.
 331  * - More errors could be returned by lower protocol layers.
 332  *
 333  * @see udp_disconnect() udp_sendto()
 334  */
 335 err_t
 336 udp_send(struct udp_pcb *pcb, struct pbuf *p)
 337 {
 338   /* send to the packet using remote ip and port stored in the pcb */
 339   return udp_sendto(pcb, p, &pcb->remote_ip, pcb->remote_port);
 340 }
 341
 342 /**
 343  * Send data to a specified address using UDP.
 344  *
 345  * @param pcb UDP PCB used to send the data.
 346  * @param p chain of pbuf's to be sent.
 347  * @param dst_ip Destination IP address.
 348  * @param dst_port Destination UDP port.
 349  *
 350  * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
 351  *
 352  * If the PCB already has a remote address association, it will
 353  * be restored after the data is sent.
 354  *
 355  * @return lwIP error code (@see udp_send for possible error codes)
 356  *
 357  * @see udp_disconnect() udp_send()
 358  */
 359 err_t
 360 udp_sendto(struct udp_pcb *pcb, struct pbuf *p,
 361   struct ip_addr *dst_ip, u16_t dst_port)
 362 {
 363   struct netif *netif;
 364
 365   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send\n"));
 366
 367   /* find the outgoing network interface for this packet */
 368 #if LWIP_IGMP
 369   netif = ip_route((ip_addr_ismulticast(dst_ip))?(&(pcb->multicast_ip)):(dst_ip));
 370 #else
 371   netif = ip_route(dst_ip);
 372 #endif /* LWIP_IGMP */
 373
 374   /* no outgoing network interface could be found? */
 375   if (netif == NULL) {
 376     LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: No route to 0x%"X32_F"\n", dst_ip->addr));
 377     UDP_STATS_INC(udp.rterr);
 378     return ERR_RTE;
 379   }
 380   return udp_sendto_if(pcb, p, dst_ip, dst_port, netif);
 381 }
 382
 383 /**
 384  * Send data to a specified address using UDP.
 385  * The netif used for sending can be specified.
 386  *
 387  * This function exists mainly for DHCP, to be able to send UDP packets
 388  * on a netif that is still down.
 389  *
 390  * @param pcb UDP PCB used to send the data.
 391  * @param p chain of pbuf's to be sent.
 392  * @param dst_ip Destination IP address.
 393  * @param dst_port Destination UDP port.
 394  * @param netif the netif used for sending.
 395  *
 396  * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
 397  *
 398  * @return lwIP error code (@see udp_send for possible error codes)
 399  *
 400  * @see udp_disconnect() udp_send()
 401  */
 402 err_t
 403 udp_sendto_if(struct udp_pcb *pcb, struct pbuf *p,
 404   struct ip_addr *dst_ip, u16_t dst_port, struct netif *netif)
 405 {
 406   struct udp_hdr *udphdr;
 407   struct ip_addr *src_ip;
 408   err_t err;
 409   struct pbuf *q; /* q will be sent down the stack */
 410
 411 #if IP_SOF_BROADCAST
 412   /* broadcast filter? */
 413   if ( ((pcb->so_options & SOF_BROADCAST) == 0) && ip_addr_isbroadcast(dst_ip, netif) ) {
 414     LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
 415       ("udp_sendto_if: SOF_BROADCAST not enabled on pcb %p\n", (void *)pcb));
 416     return ERR_VAL;
 417   }
 418 #endif /* IP_SOF_BROADCAST */
 419
 420   /* if the PCB is not yet bound to a port, bind it here */
 421   if (pcb->local_port == 0) {
 422     LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send: not yet bound to a port, binding now\n"));
 423     err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);
 424     if (err != ERR_OK) {
 425       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: forced port bind failed\n"));
 426       return err;
 427     }
 428   }
 429
 430   /* not enough space to add an UDP header to first pbuf in given p chain? */
 431   if (pbuf_header(p, UDP_HLEN)) {
 432     /* allocate header in a separate new pbuf */
 433     q = pbuf_alloc(PBUF_IP, UDP_HLEN, PBUF_RAM);
 434     /* new header pbuf could not be allocated? */
 435     if (q == NULL) {
 436       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: could not allocate header\n"));
 437       return ERR_MEM;
 438     }
 439     /* chain header q in front of given pbuf p */
 440     pbuf_chain(q, p);
 441     /* first pbuf q points to header pbuf */
 442     LWIP_DEBUGF(UDP_DEBUG,
 443                 ("udp_send: added header pbuf %p before given pbuf %p\n", (void *)q, (void *)p));
 444   } else {
 445     /* adding space for header within p succeeded */
 446     /* first pbuf q equals given pbuf */
 447     q = p;
 448     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: added header in given pbuf %p\n", (void *)p));
 449   }
 450   LWIP_ASSERT("check that first pbuf can hold struct udp_hdr",
 451               (q->len >= sizeof(struct udp_hdr)));
 452   /* q now represents the packet to be sent */
 453   udphdr = q->payload;
 454   udphdr->src = htons(pcb->local_port);
 455   udphdr->dest = htons(dst_port);
 456   /* in UDP, 0 checksum means 'no checksum' */
 457   udphdr->chksum = 0x0000;
 458
 459   /* PCB local address is IP_ANY_ADDR? */
 460   if (ip_addr_isany(&pcb->local_ip)) {
 461     /* use outgoing network interface IP address as source address */
 462     src_ip = &(netif->ip_addr);
 463   } else {
 464     /* check if UDP PCB local IP address is correct
 465      * this could be an old address if netif->ip_addr has changed */
 466     if (!ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) {
 467       /* local_ip doesn't match, drop the packet */
 468       if (q != p) {
 469         /* free the header pbuf */
 470         pbuf_free(q);
 471         q = NULL;
 472         /* p is still referenced by the caller, and will live on */
 473       }
 474       return ERR_VAL;
 475     }
 476     /* use UDP PCB local IP address as source address */
 477     src_ip = &(pcb->local_ip);
 478   }
 479
 480   LWIP_DEBUGF(UDP_DEBUG, ("udp_send: sending datagram of length %"U16_F"\n", q->tot_len));
 481
 482 #if LWIP_UDPLITE
 483   /* UDP Lite protocol? */
 484   if (pcb->flags & UDP_FLAGS_UDPLITE) {
 485     u16_t chklen, chklen_hdr;
 486     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE packet length %"U16_F"\n", q->tot_len));
 487     /* set UDP message length in UDP header */
 488     chklen_hdr = chklen = pcb->chksum_len_tx;
 489     if ((chklen < sizeof(struct udp_hdr)) || (chklen > q->tot_len)) {
 490       if (chklen != 0) {
 491         LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE pcb->chksum_len is illegal: %"U16_F"\n", chklen));
 492       }
 493       /* For UDP-Lite, checksum length of 0 means checksum
 494          over the complete packet. (See RFC 3828 chap. 3.1)
 495          At least the UDP-Lite header must be covered by the
 496          checksum, therefore, if chksum_len has an illegal
 497          value, we generate the checksum over the complete
 498          packet to be safe. */
 499       chklen_hdr = 0;
 500       chklen = q->tot_len;
 501     }
 502     udphdr->len = htons(chklen_hdr);
 503     /* calculate checksum */
 504 #if CHECKSUM_GEN_UDP
 505     udphdr->chksum = inet_chksum_pseudo_partial(q, src_ip, dst_ip,
 506                                         IP_PROTO_UDPLITE, q->tot_len, chklen);
 507     /* chksum zero must become 0xffff, as zero means 'no checksum' */
 508     if (udphdr->chksum == 0x0000)
 509       udphdr->chksum = 0xffff;
 510 #endif /* CHECKSUM_CHECK_UDP */
 511     /* output to IP */
 512     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDPLITE,)\n"));
 513 #if LWIP_NETIF_HWADDRHINT
 514     netif->addr_hint = &(pcb->addr_hint);
 515 #endif /* LWIP_NETIF_HWADDRHINT*/
 516     err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDPLITE, netif);
 517 #if LWIP_NETIF_HWADDRHINT
 518     netif->addr_hint = NULL;
 519 #endif /* LWIP_NETIF_HWADDRHINT*/
 520   } else
 521 #endif /* LWIP_UDPLITE */
 522   {      /* UDP */
 523     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP packet length %"U16_F"\n", q->tot_len));
 524     udphdr->len = htons(q->tot_len);
 525     /* calculate checksum */
 526 #if CHECKSUM_GEN_UDP
 527     if ((pcb->flags & UDP_FLAGS_NOCHKSUM) == 0) {
 528       udphdr->chksum = inet_chksum_pseudo(q, src_ip, dst_ip, IP_PROTO_UDP, q->tot_len);
 529       /* chksum zero must become 0xffff, as zero means 'no checksum' */
 530       if (udphdr->chksum == 0x0000) udphdr->chksum = 0xffff;
 531     }
 532 #endif /* CHECKSUM_CHECK_UDP */
 533     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04"X16_F"\n", udphdr->chksum));
 534     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDP,)\n"));
 535     /* output to IP */
 536 #if LWIP_NETIF_HWADDRHINT
 537     netif->addr_hint = &(pcb->addr_hint);
 538 #endif /* LWIP_NETIF_HWADDRHINT*/
 539     err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDP, netif);
 540 #if LWIP_NETIF_HWADDRHINT
 541     netif->addr_hint = NULL;
 542 #endif /* LWIP_NETIF_HWADDRHINT*/
 543   }
 544   /* TODO: must this be increased even if error occured? */
 545   snmp_inc_udpoutdatagrams();
 546
 547   /* did we chain a separate header pbuf earlier? */
 548   if (q != p) {
 549     /* free the header pbuf */
 550     pbuf_free(q);
 551     q = NULL;
 552     /* p is still referenced by the caller, and will live on */
 553   }
 554
 555   UDP_STATS_INC(udp.xmit);
 556   return err;
 557 }
 558
 559 /**
 560  * Bind an UDP PCB.
 561  *
 562  * @param pcb UDP PCB to be bound with a local address ipaddr and port.
 563  * @param ipaddr local IP address to bind with. Use IP_ADDR_ANY to
 564  * bind to all local interfaces.
 565  * @param port local UDP port to bind with. Use 0 to automatically bind
 566  * to a random port between UDP_LOCAL_PORT_RANGE_START and
 567  * UDP_LOCAL_PORT_RANGE_END.
 568  *
 569  * ipaddr & port are expected to be in the same byte order as in the pcb.
 570  *
 571  * @return lwIP error code.
 572  * - ERR_OK. Successful. No error occured.
 573  * - ERR_USE. The specified ipaddr and port are already bound to by
 574  * another UDP PCB.
 575  *
 576  * @see udp_disconnect()
 577  */
 578 err_t
 579 udp_bind(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
 580 {
 581   struct udp_pcb *ipcb;
 582   u8_t rebind;
 583
 584   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_bind(ipaddr = "));
 585   ip_addr_debug_print(UDP_DEBUG, ipaddr);
 586   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, (", port = %"U16_F")\n", port));
 587
 588   rebind = 0;
 589   /* Check for double bind and rebind of the same pcb */
 590   for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
 591     /* is this UDP PCB already on active list? */
 592     if (pcb == ipcb) {
 593       /* pcb may occur at most once in active list */
 594       LWIP_ASSERT("rebind == 0", rebind == 0);
 595       /* pcb already in list, just rebind */
 596       rebind = 1;
 597     }
 598
 599     /* this code does not allow upper layer to share a UDP port for
 600        listening to broadcast or multicast traffic (See SO_REUSE_ADDR and
 601        SO_REUSE_PORT under *BSD). TODO: See where it fits instead, OR
 602        combine with implementation of UDP PCB flags. Leon Woestenberg. */
 603 #ifdef LWIP_UDP_TODO
 604     /* port matches that of PCB in list? */
 605     else
 606       if ((ipcb->local_port == port) &&
 607           /* IP address matches, or one is IP_ADDR_ANY? */
 608           (ip_addr_isany(&(ipcb->local_ip)) ||
 609            ip_addr_isany(ipaddr) ||
 610            ip_addr_cmp(&(ipcb->local_ip), ipaddr))) {
 611         /* other PCB already binds to this local IP and port */
 612         LWIP_DEBUGF(UDP_DEBUG,
 613                     ("udp_bind: local port %"U16_F" already bound by another pcb\n", port));
 614         return ERR_USE;
 615       }
 616 #endif
 617   }
 618
 619   ip_addr_set(&pcb->local_ip, ipaddr);
 620
 621   /* no port specified? */
 622   if (port == 0) {
 623 #ifndef UDP_LOCAL_PORT_RANGE_START
 624 #define UDP_LOCAL_PORT_RANGE_START 4096
 625 #define UDP_LOCAL_PORT_RANGE_END   0x7fff
 626 #endif
 627     port = UDP_LOCAL_PORT_RANGE_START;
 628     ipcb = udp_pcbs;
 629     while ((ipcb != NULL) && (port != UDP_LOCAL_PORT_RANGE_END)) {
 630       if (ipcb->local_port == port) {
 631         /* port is already used by another udp_pcb */
 632         port++;
 633         /* restart scanning all udp pcbs */
 634         ipcb = udp_pcbs;
 635       } else
 636         /* go on with next udp pcb */
 637         ipcb = ipcb->next;
 638     }
 639     if (ipcb != NULL) {
 640       /* no more ports available in local range */
 641       LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: out of free UDP ports\n"));
 642       return ERR_USE;
 643     }
 644   }
 645   pcb->local_port = port;
 646   snmp_insert_udpidx_tree(pcb);
 647   /* pcb not active yet? */
 648   if (rebind == 0) {
 649     /* place the PCB on the active list if not already there */
 650     pcb->next = udp_pcbs;
 651     udp_pcbs = pcb;
 652   }
 653   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
 654               ("udp_bind: bound to %"U16_F".%"U16_F".%"U16_F".%"U16_F", port %"U16_F"\n",
 655                (u16_t)((ntohl(pcb->local_ip.addr) >> 24) & 0xff),
 656                (u16_t)((ntohl(pcb->local_ip.addr) >> 16) & 0xff),
 657                (u16_t)((ntohl(pcb->local_ip.addr) >> 8) & 0xff),
 658                (u16_t)(ntohl(pcb->local_ip.addr) & 0xff), pcb->local_port));
 659   return ERR_OK;
 660 }
 661 /**
 662  * Connect an UDP PCB.
 663  *
 664  * This will associate the UDP PCB with the remote address.
 665  *
 666  * @param pcb UDP PCB to be connected with remote address ipaddr and port.
 667  * @param ipaddr remote IP address to connect with.
 668  * @param port remote UDP port to connect with.
 669  *
 670  * @return lwIP error code
 671  *
 672  * ipaddr & port are expected to be in the same byte order as in the pcb.
 673  *
 674  * The udp pcb is bound to a random local port if not already bound.
 675  *
 676  * @see udp_disconnect()
 677  */
 678 err_t
 679 udp_connect(struct udp_pcb *pcb, struct ip_addr *ipaddr, u16_t port)
 680 {
 681   struct udp_pcb *ipcb;
 682
 683   if (pcb->local_port == 0) {
 684     err_t err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);
 685     if (err != ERR_OK)
 686       return err;
 687   }
 688
 689   ip_addr_set(&pcb->remote_ip, ipaddr);
 690   pcb->remote_port = port;
 691   pcb->flags |= UDP_FLAGS_CONNECTED;
 692 /** TODO: this functionality belongs in upper layers */
 693 #ifdef LWIP_UDP_TODO
 694   /* Nail down local IP for netconn_addr()/getsockname() */
 695   if (ip_addr_isany(&pcb->local_ip) && !ip_addr_isany(&pcb->remote_ip)) {
 696     struct netif *netif;
 697
 698     if ((netif = ip_route(&(pcb->remote_ip))) == NULL) {
 699       LWIP_DEBUGF(UDP_DEBUG, ("udp_connect: No route to 0x%lx\n", pcb->remote_ip.addr));
 700       UDP_STATS_INC(udp.rterr);
 701       return ERR_RTE;
 702     }
 703     /** TODO: this will bind the udp pcb locally, to the interface which
 704         is used to route output packets to the remote address. However, we
 705         might want to accept incoming packets on any interface! */
 706     pcb->local_ip = netif->ip_addr;
 707   } else if (ip_addr_isany(&pcb->remote_ip)) {
 708     pcb->local_ip.addr = 0;
 709   }
 710 #endif
 711   LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
 712               ("udp_connect: connected to %"U16_F".%"U16_F".%"U16_F".%"U16_F",port %"U16_F"\n",
 713                (u16_t)((ntohl(pcb->remote_ip.addr) >> 24) & 0xff),
 714                (u16_t)((ntohl(pcb->remote_ip.addr) >> 16) & 0xff),
 715                (u16_t)((ntohl(pcb->remote_ip.addr) >> 8) & 0xff),
 716                (u16_t)(ntohl(pcb->remote_ip.addr) & 0xff), pcb->remote_port));
 717
 718   /* Insert UDP PCB into the list of active UDP PCBs. */
 719   for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
 720     if (pcb == ipcb) {
 721       /* already on the list, just return */
 722       return ERR_OK;
 723     }
 724   }
 725   /* PCB not yet on the list, add PCB now */
 726   pcb->next = udp_pcbs;
 727   udp_pcbs = pcb;
 728   return ERR_OK;
 729 }
 730
 731 /**
 732  * Disconnect a UDP PCB
 733  *
 734  * @param pcb the udp pcb to disconnect.
 735  */
 736 void
 737 udp_disconnect(struct udp_pcb *pcb)
 738 {
 739   /* reset remote address association */
 740   ip_addr_set(&pcb->remote_ip, IP_ADDR_ANY);
 741   pcb->remote_port = 0;
 742   /* mark PCB as unconnected */
 743   pcb->flags &= ~UDP_FLAGS_CONNECTED;
 744 }
 745
 746 /**
 747  * Set a receive callback for a UDP PCB
 748  *
 749  * This callback will be called when receiving a datagram for the pcb.
 750  *
 751  * @param pcb the pcb for wich to set the recv callback
 752  * @param recv function pointer of the callback function
 753  * @param recv_arg additional argument to pass to the callback function
 754  */
 755 void
 756 udp_recv(struct udp_pcb *pcb,
 757          void (* recv)(void *arg, struct udp_pcb *upcb, struct pbuf *p,
 758                        struct ip_addr *addr, u16_t port),
 759          void *recv_arg)
 760 {
 761   /* remember recv() callback and user data */
 762   pcb->recv = recv;
 763   pcb->recv_arg = recv_arg;
 764 }
 765
 766 /**
 767  * Remove an UDP PCB.
 768  *
 769  * @param pcb UDP PCB to be removed. The PCB is removed from the list of
 770  * UDP PCB's and the data structure is freed from memory.
 771  *
 772  * @see udp_new()
 773  */
 774 void
 775 udp_remove(struct udp_pcb *pcb)
 776 {
 777   struct udp_pcb *pcb2;
 778
 779   snmp_delete_udpidx_tree(pcb);
 780   /* pcb to be removed is first in list? */
 781   if (udp_pcbs == pcb) {
 782     /* make list start at 2nd pcb */
 783     udp_pcbs = udp_pcbs->next;
 784     /* pcb not 1st in list */
 785   } else
 786     for (pcb2 = udp_pcbs; pcb2 != NULL; pcb2 = pcb2->next) {
 787       /* find pcb in udp_pcbs list */
 788       if (pcb2->next != NULL && pcb2->next == pcb) {
 789         /* remove pcb from list */
 790         pcb2->next = pcb->next;
 791       }
 792     }
 793   memp_free(MEMP_UDP_PCB, pcb);
 794 }
 795
 796 /**
 797  * Create a UDP PCB.
 798  *
 799  * @return The UDP PCB which was created. NULL if the PCB data structure
 800  * could not be allocated.
 801  *
 802  * @see udp_remove()
 803  */
 804 struct udp_pcb *
 805 udp_new(void)
 806 {
 807   struct udp_pcb *pcb;
 808   pcb = memp_malloc(MEMP_UDP_PCB);
 809   /* could allocate UDP PCB? */
 810   if (pcb != NULL) {
 811     /* UDP Lite: by initializing to all zeroes, chksum_len is set to 0
 812      * which means checksum is generated over the whole datagram per default
 813      * (recommended as default by RFC 3828). */
 814     /* initialize PCB to all zeroes */
 815     memset(pcb, 0, sizeof(struct udp_pcb));
 816     pcb->ttl = UDP_TTL;
 817   }
 818   return pcb;
 819 }
 820
 821 #if UDP_DEBUG
 822 /**
 823  * Print UDP header information for debug purposes.
 824  *
 825  * @param udphdr pointer to the udp header in memory.
 826  */
 827 void
 828 udp_debug_print(struct udp_hdr *udphdr)
 829 {
 830   LWIP_DEBUGF(UDP_DEBUG, ("UDP header:\n"));
 831   LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
 832   LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     %5"U16_F"     | (src port, dest port)\n",
 833                           ntohs(udphdr->src), ntohs(udphdr->dest)));
 834   LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
 835   LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     0x%04"X16_F"    | (len, chksum)\n",
 836                           ntohs(udphdr->len), ntohs(udphdr->chksum)));
 837   LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
 838 }
 839 #endif /* UDP_DEBUG */
 840
 841 #endif /* LWIP_UDP */