Diff: lwip/core/udp.c

Revision:

12:8dc6b255af6c

Parent:

11:da4498f591ee

diff -r da4498f591ee -r 8dc6b255af6c lwip/core/udp.c
--- a/lwip/core/udp.c	Thu Aug 05 15:01:33 2010 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,962 +0,0 @@
-/**
- * @file
- * User Datagram Protocol module
- *
- */
-
-/*
- * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- *
- * Author: Adam Dunkels <adam@sics.se>
- *
- */
-
-
-/* udp.c
- *
- * The code for the User Datagram Protocol UDP & UDPLite (RFC 3828).
- *
- */
-
-/* @todo Check the use of '(struct udp_pcb).chksum_len_rx'!
- */
-
-#include "lwip/opt.h"
-
-#if LWIP_UDP /* don't build if not configured for use in lwipopts.h */
-
-#include "lwip/udp.h"
-#include "lwip/def.h"
-#include "lwip/memp.h"
-#include "lwip/inet_chksum.h"
-#include "lwip/ip_addr.h"
-#include "lwip/netif.h"
-#include "lwip/icmp.h"
-#include "lwip/stats.h"
-#include "lwip/snmp.h"
-#include "arch/perf.h"
-#include "lwip/dhcp.h"
-
-#include <string.h>
-
-/* The list of UDP PCBs */
-/* exported in udp.h (was static) */
-struct udp_pcb *udp_pcbs;
-
-/**
- * Process an incoming UDP datagram.
- *
- * Given an incoming UDP datagram (as a chain of pbufs) this function
- * finds a corresponding UDP PCB and hands over the pbuf to the pcbs
- * recv function. If no pcb is found or the datagram is incorrect, the
- * pbuf is freed.
- *
- * @param p pbuf to be demultiplexed to a UDP PCB.
- * @param inp network interface on which the datagram was received.
- *
- */
-void
-udp_input(struct pbuf *p, struct netif *inp)
-{
-  struct udp_hdr *udphdr;
-  struct udp_pcb *pcb, *prev;
-  struct udp_pcb *uncon_pcb;
-  struct ip_hdr *iphdr;
-  u16_t src, dest;
-  u8_t local_match;
-  u8_t broadcast;
-
-  PERF_START;
-
-  UDP_STATS_INC(udp.recv);
-
-  iphdr = (struct ip_hdr *)p->payload;
-
-  /* Check minimum length (IP header + UDP header)
-   * and move payload pointer to UDP header */
-  if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
-    /* drop short packets */
-    LWIP_DEBUGF(UDP_DEBUG,
-                ("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
-    UDP_STATS_INC(udp.lenerr);
-    UDP_STATS_INC(udp.drop);
-    snmp_inc_udpinerrors();
-    pbuf_free(p);
-    goto end;
-  }
-
-  udphdr = (struct udp_hdr *)p->payload;
-
-  /* is broadcast packet ? */
-  broadcast = ip_addr_isbroadcast(&current_iphdr_dest, inp);
-
-  LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));
-
-  /* convert src and dest ports to host byte order */
-  src = ntohs(udphdr->src);
-  dest = ntohs(udphdr->dest);
-
-  udp_debug_print(udphdr);
-
-  /* print the UDP source and destination */
-  LWIP_DEBUGF(UDP_DEBUG,
-              ("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
-               "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
-               ip4_addr1_16(&iphdr->dest), ip4_addr2_16(&iphdr->dest),
-               ip4_addr3_16(&iphdr->dest), ip4_addr4_16(&iphdr->dest), ntohs(udphdr->dest),
-               ip4_addr1_16(&iphdr->src), ip4_addr2_16(&iphdr->src),
-               ip4_addr3_16(&iphdr->src), ip4_addr4_16(&iphdr->src), ntohs(udphdr->src)));
-
-#if LWIP_DHCP
-  pcb = NULL;
-  /* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
-     the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
-  if (dest == DHCP_CLIENT_PORT) {
-    /* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
-    if (src == DHCP_SERVER_PORT) {
-      if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
-        /* accept the packe if 
-           (- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
-           - inp->dhcp->pcb->remote == ANY or iphdr->src */
-        if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
-           ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), &current_iphdr_src))) {
-          pcb = inp->dhcp->pcb;
-        }
-      }
-    }
-  } else
-#endif /* LWIP_DHCP */
-  {
-    prev = NULL;
-    local_match = 0;
-    uncon_pcb = NULL;
-    /* Iterate through the UDP pcb list for a matching pcb.
-     * 'Perfect match' pcbs (connected to the remote port & ip address) are
-     * preferred. If no perfect match is found, the first unconnected pcb that
-     * matches the local port and ip address gets the datagram. */
-    for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
-      local_match = 0;
-      /* print the PCB local and remote address */
-      LWIP_DEBUGF(UDP_DEBUG,
-                  ("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
-                   "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
-                   ip4_addr1_16(&pcb->local_ip), ip4_addr2_16(&pcb->local_ip),
-                   ip4_addr3_16(&pcb->local_ip), ip4_addr4_16(&pcb->local_ip), pcb->local_port,
-                   ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
-                   ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip), pcb->remote_port));
-
-      /* compare PCB local addr+port to UDP destination addr+port */
-      if ((pcb->local_port == dest) &&
-          ((!broadcast && ip_addr_isany(&pcb->local_ip)) ||
-           ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest) ||
-#if LWIP_IGMP
-           ip_addr_ismulticast(&current_iphdr_dest) ||
-#endif /* LWIP_IGMP */
-#if IP_SOF_BROADCAST_RECV
-           (broadcast && (pcb->so_options & SOF_BROADCAST)))) {
-#else  /* IP_SOF_BROADCAST_RECV */
-           (broadcast))) {
-#endif /* IP_SOF_BROADCAST_RECV */
-        local_match = 1;
-        if ((uncon_pcb == NULL) && 
-            ((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
-          /* the first unconnected matching PCB */
-          uncon_pcb = pcb;
-        }
-      }
-      /* compare PCB remote addr+port to UDP source addr+port */
-      if ((local_match != 0) &&
-          (pcb->remote_port == src) &&
-          (ip_addr_isany(&pcb->remote_ip) ||
-           ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src))) {
-        /* the first fully matching PCB */
-        if (prev != NULL) {
-          /* move the pcb to the front of udp_pcbs so that is
-             found faster next time */
-          prev->next = pcb->next;
-          pcb->next = udp_pcbs;
-          udp_pcbs = pcb;
-        } else {
-          UDP_STATS_INC(udp.cachehit);
-        }
-        break;
-      }
-      prev = pcb;
-    }
-    /* no fully matching pcb found? then look for an unconnected pcb */
-    if (pcb == NULL) {
-      pcb = uncon_pcb;
-    }
-  }
-
-  /* Check checksum if this is a match or if it was directed at us. */
-  if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, &current_iphdr_dest)) {
-    LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
-#if LWIP_UDPLITE
-    if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
-      /* Do the UDP Lite checksum */
-#if CHECKSUM_CHECK_UDP
-      u16_t chklen = ntohs(udphdr->len);
-      if (chklen < sizeof(struct udp_hdr)) {
-        if (chklen == 0) {
-          /* For UDP-Lite, checksum length of 0 means checksum
-             over the complete packet (See RFC 3828 chap. 3.1) */
-          chklen = p->tot_len;
-        } else {
-          /* At least the UDP-Lite header must be covered by the
-             checksum! (Again, see RFC 3828 chap. 3.1) */
-          UDP_STATS_INC(udp.chkerr);
-          UDP_STATS_INC(udp.drop);
-          snmp_inc_udpinerrors();
-          pbuf_free(p);
-          goto end;
-        }
-      }
-      if (inet_chksum_pseudo_partial(p, &current_iphdr_src, &current_iphdr_dest,
-                             IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
-       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
-                   ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
-        UDP_STATS_INC(udp.chkerr);
-        UDP_STATS_INC(udp.drop);
-        snmp_inc_udpinerrors();
-        pbuf_free(p);
-        goto end;
-      }
-#endif /* CHECKSUM_CHECK_UDP */
-    } else
-#endif /* LWIP_UDPLITE */
-    {
-#if CHECKSUM_CHECK_UDP
-      if (udphdr->chksum != 0) {
-        if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
-                               IP_PROTO_UDP, p->tot_len) != 0) {
-          LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
-                      ("udp_input: UDP datagram discarded due to failing checksum\n"));
-          UDP_STATS_INC(udp.chkerr);
-          UDP_STATS_INC(udp.drop);
-          snmp_inc_udpinerrors();
-          pbuf_free(p);
-          goto end;
-        }
-      }
-#endif /* CHECKSUM_CHECK_UDP */
-    }
-    if(pbuf_header(p, -UDP_HLEN)) {
-      /* Can we cope with this failing? Just assert for now */
-      LWIP_ASSERT("pbuf_header failed\n", 0);
-      UDP_STATS_INC(udp.drop);
-      snmp_inc_udpinerrors();
-      pbuf_free(p);
-      goto end;
-    }
-    if (pcb != NULL) {
-      snmp_inc_udpindatagrams();
-#if SO_REUSE && SO_REUSE_RXTOALL
-      if ((broadcast || ip_addr_ismulticast(&current_iphdr_dest)) &&
-          ((pcb->so_options & SOF_REUSEADDR) != 0)) {
-        /* pass broadcast- or multicast packets to all multicast pcbs
-           if SOF_REUSEADDR is set on the first match */
-        struct udp_pcb *mpcb;
-        u8_t p_header_changed = 0;
-        for (mpcb = udp_pcbs; mpcb != NULL; mpcb = mpcb->next) {
-          if (mpcb != pcb) {
-            /* compare PCB local addr+port to UDP destination addr+port */
-            if ((mpcb->local_port == dest) &&
-                ((!broadcast && ip_addr_isany(&mpcb->local_ip)) ||
-                 ip_addr_cmp(&(mpcb->local_ip), &current_iphdr_dest) ||
-#if LWIP_IGMP
-                 ip_addr_ismulticast(&current_iphdr_dest) ||
-#endif /* LWIP_IGMP */
-#if IP_SOF_BROADCAST_RECV
-                 (broadcast && (mpcb->so_options & SOF_BROADCAST)))) {
-#else  /* IP_SOF_BROADCAST_RECV */
-                 (broadcast))) {
-#endif /* IP_SOF_BROADCAST_RECV */
-              /* pass a copy of the packet to all local matches */
-              if (mpcb->recv != NULL) {
-                struct pbuf *q;
-                /* for that, move payload to IP header again */
-                if (p_header_changed == 0) {
-                  pbuf_header(p, (s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
-                  p_header_changed = 1;
-                }
-                q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
-                if (q != NULL) {
-                  err_t err = pbuf_copy(q, p);
-                  if (err == ERR_OK) {
-                    /* move payload to UDP data */
-                    pbuf_header(q, -(s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
-                    mpcb->recv(mpcb->recv_arg, mpcb, q, ip_current_src_addr(), src);
-                  }
-                }
-              }
-            }
-          }
-        }
-        if (p_header_changed) {
-          /* and move payload to UDP data again */
-          pbuf_header(p, -(s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
-        }
-      }
-#endif /* SO_REUSE && SO_REUSE_RXTOALL */
-      /* callback */
-      if (pcb->recv != NULL) {
-        /* now the recv function is responsible for freeing p */
-        pcb->recv(pcb->recv_arg, pcb, p, ip_current_src_addr(), src);
-      } else {
-        /* no recv function registered? then we have to free the pbuf! */
-        pbuf_free(p);
-        goto end;
-      }
-    } else {
-      LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: not for us.\n"));
-
-#if LWIP_ICMP
-      /* No match was found, send ICMP destination port unreachable unless
-         destination address was broadcast/multicast. */
-      if (!broadcast &&
-          !ip_addr_ismulticast(&current_iphdr_dest)) {
-        /* move payload pointer back to ip header */
-        pbuf_header(p, (IPH_HL(iphdr) * 4) + UDP_HLEN);
-        LWIP_ASSERT("p->payload == iphdr", (p->payload == iphdr));
-        icmp_dest_unreach(p, ICMP_DUR_PORT);
-      }
-#endif /* LWIP_ICMP */
-      UDP_STATS_INC(udp.proterr);
-      UDP_STATS_INC(udp.drop);
-      snmp_inc_udpnoports();
-      pbuf_free(p);
-    }
-  } else {
-    pbuf_free(p);
-  }
-end:
-  PERF_STOP("udp_input");
-}
-
-/**
- * Send data using UDP.
- *
- * @param pcb UDP PCB used to send the data.
- * @param p chain of pbuf's to be sent.
- *
- * The datagram will be sent to the current remote_ip & remote_port
- * stored in pcb. If the pcb is not bound to a port, it will
- * automatically be bound to a random port.
- *
- * @return lwIP error code.
- * - ERR_OK. Successful. No error occured.
- * - ERR_MEM. Out of memory.
- * - ERR_RTE. Could not find route to destination address.
- * - More errors could be returned by lower protocol layers.
- *
- * @see udp_disconnect() udp_sendto()
- */
-err_t
-udp_send(struct udp_pcb *pcb, struct pbuf *p)
-{
-  /* send to the packet using remote ip and port stored in the pcb */
-  return udp_sendto(pcb, p, &pcb->remote_ip, pcb->remote_port);
-}
-
-#if LWIP_CHECKSUM_ON_COPY
-/** Same as udp_send() but with checksum
- */
-err_t
-udp_send_chksum(struct udp_pcb *pcb, struct pbuf *p,
-                u8_t have_chksum, u16_t chksum)
-{
-  /* send to the packet using remote ip and port stored in the pcb */
-  return udp_sendto_chksum(pcb, p, &pcb->remote_ip, pcb->remote_port,
-    have_chksum, chksum);
-}
-#endif /* LWIP_CHECKSUM_ON_COPY */
-
-/**
- * Send data to a specified address using UDP.
- *
- * @param pcb UDP PCB used to send the data.
- * @param p chain of pbuf's to be sent.
- * @param dst_ip Destination IP address.
- * @param dst_port Destination UDP port.
- *
- * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
- *
- * If the PCB already has a remote address association, it will
- * be restored after the data is sent.
- * 
- * @return lwIP error code (@see udp_send for possible error codes)
- *
- * @see udp_disconnect() udp_send()
- */
-err_t
-udp_sendto(struct udp_pcb *pcb, struct pbuf *p,
-  ip_addr_t *dst_ip, u16_t dst_port)
-{
-#if LWIP_CHECKSUM_ON_COPY
-  return udp_sendto_chksum(pcb, p, dst_ip, dst_port, 0, 0);
-}
-
-/** Same as udp_sendto(), but with checksum */
-err_t
-udp_sendto_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
-                  u16_t dst_port, u8_t have_chksum, u16_t chksum)
-{
-#endif /* LWIP_CHECKSUM_ON_COPY */
-  struct netif *netif;
-
-  LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send\n"));
-
-  /* find the outgoing network interface for this packet */
-#if LWIP_IGMP
-  netif = ip_route((ip_addr_ismulticast(dst_ip))?(&(pcb->multicast_ip)):(dst_ip));
-#else
-  netif = ip_route(dst_ip);
-#endif /* LWIP_IGMP */
-
-  /* no outgoing network interface could be found? */
-  if (netif == NULL) {
-    LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
-      ip4_addr1_16(dst_ip), ip4_addr2_16(dst_ip), ip4_addr3_16(dst_ip), ip4_addr4_16(dst_ip)));
-    UDP_STATS_INC(udp.rterr);
-    return ERR_RTE;
-  }
-#if LWIP_CHECKSUM_ON_COPY
-  return udp_sendto_if_chksum(pcb, p, dst_ip, dst_port, netif, have_chksum, chksum);
-#else /* LWIP_CHECKSUM_ON_COPY */
-  return udp_sendto_if(pcb, p, dst_ip, dst_port, netif);
-#endif /* LWIP_CHECKSUM_ON_COPY */
-}
-
-/**
- * Send data to a specified address using UDP.
- * The netif used for sending can be specified.
- *
- * This function exists mainly for DHCP, to be able to send UDP packets
- * on a netif that is still down.
- *
- * @param pcb UDP PCB used to send the data.
- * @param p chain of pbuf's to be sent.
- * @param dst_ip Destination IP address.
- * @param dst_port Destination UDP port.
- * @param netif the netif used for sending.
- *
- * dst_ip & dst_port are expected to be in the same byte order as in the pcb.
- *
- * @return lwIP error code (@see udp_send for possible error codes)
- *
- * @see udp_disconnect() udp_send()
- */
-err_t
-udp_sendto_if(struct udp_pcb *pcb, struct pbuf *p,
-  ip_addr_t *dst_ip, u16_t dst_port, struct netif *netif)
-{
-#if LWIP_CHECKSUM_ON_COPY
-  return udp_sendto_if_chksum(pcb, p, dst_ip, dst_port, netif, 0, 0);
-}
-
-/** Same as udp_sendto_if(), but with checksum */
-err_t
-udp_sendto_if_chksum(struct udp_pcb *pcb, struct pbuf *p, ip_addr_t *dst_ip,
-                     u16_t dst_port, struct netif *netif, u8_t have_chksum,
-                     u16_t chksum)
-{
-#endif /* LWIP_CHECKSUM_ON_COPY */
-  struct udp_hdr *udphdr;
-  ip_addr_t *src_ip;
-  err_t err;
-  struct pbuf *q; /* q will be sent down the stack */
-
-#if IP_SOF_BROADCAST
-  /* broadcast filter? */
-  if ( ((pcb->so_options & SOF_BROADCAST) == 0) && ip_addr_isbroadcast(dst_ip, netif) ) {
-    LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
-      ("udp_sendto_if: SOF_BROADCAST not enabled on pcb %p\n", (void *)pcb));
-    return ERR_VAL;
-  }
-#endif /* IP_SOF_BROADCAST */
-
-  /* if the PCB is not yet bound to a port, bind it here */
-  if (pcb->local_port == 0) {
-    LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_send: not yet bound to a port, binding now\n"));
-    err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);
-    if (err != ERR_OK) {
-      LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: forced port bind failed\n"));
-      return err;
-    }
-  }
-
-  /* not enough space to add an UDP header to first pbuf in given p chain? */
-  if (pbuf_header(p, UDP_HLEN)) {
-    /* allocate header in a separate new pbuf */
-    q = pbuf_alloc(PBUF_IP, UDP_HLEN, PBUF_RAM);
-    /* new header pbuf could not be allocated? */
-    if (q == NULL) {
-      LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_LEVEL_SERIOUS, ("udp_send: could not allocate header\n"));
-      return ERR_MEM;
-    }
-    /* chain header q in front of given pbuf p */
-    pbuf_chain(q, p);
-    /* first pbuf q points to header pbuf */
-    LWIP_DEBUGF(UDP_DEBUG,
-                ("udp_send: added header pbuf %p before given pbuf %p\n", (void *)q, (void *)p));
-  } else {
-    /* adding space for header within p succeeded */
-    /* first pbuf q equals given pbuf */
-    q = p;
-    LWIP_DEBUGF(UDP_DEBUG, ("udp_send: added header in given pbuf %p\n", (void *)p));
-  }
-  LWIP_ASSERT("check that first pbuf can hold struct udp_hdr",
-              (q->len >= sizeof(struct udp_hdr)));
-  /* q now represents the packet to be sent */
-  udphdr = (struct udp_hdr *)q->payload;
-  udphdr->src = htons(pcb->local_port);
-  udphdr->dest = htons(dst_port);
-  /* in UDP, 0 checksum means 'no checksum' */
-  udphdr->chksum = 0x0000; 
-
-  /* Multicast Loop? */
-#if LWIP_IGMP
-  if (ip_addr_ismulticast(dst_ip) && ((pcb->flags & UDP_FLAGS_MULTICAST_LOOP) != 0)) {
-    q->flags |= PBUF_FLAG_MCASTLOOP;
-  }
-#endif /* LWIP_IGMP */
-
-
-  /* PCB local address is IP_ANY_ADDR? */
-  if (ip_addr_isany(&pcb->local_ip)) {
-    /* use outgoing network interface IP address as source address */
-    src_ip = &(netif->ip_addr);
-  } else {
-    /* check if UDP PCB local IP address is correct
-     * this could be an old address if netif->ip_addr has changed */
-    if (!ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) {
-      /* local_ip doesn't match, drop the packet */
-      if (q != p) {
-        /* free the header pbuf */
-        pbuf_free(q);
-        q = NULL;
-        /* p is still referenced by the caller, and will live on */
-      }
-      return ERR_VAL;
-    }
-    /* use UDP PCB local IP address as source address */
-    src_ip = &(pcb->local_ip);
-  }
-
-  LWIP_DEBUGF(UDP_DEBUG, ("udp_send: sending datagram of length %"U16_F"\n", q->tot_len));
-
-#if LWIP_UDPLITE
-  /* UDP Lite protocol? */
-  if (pcb->flags & UDP_FLAGS_UDPLITE) {
-    u16_t chklen, chklen_hdr;
-    LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE packet length %"U16_F"\n", q->tot_len));
-    /* set UDP message length in UDP header */
-    chklen_hdr = chklen = pcb->chksum_len_tx;
-    if ((chklen < sizeof(struct udp_hdr)) || (chklen > q->tot_len)) {
-      if (chklen != 0) {
-        LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP LITE pcb->chksum_len is illegal: %"U16_F"\n", chklen));
-      }
-      /* For UDP-Lite, checksum length of 0 means checksum
-         over the complete packet. (See RFC 3828 chap. 3.1)
-         At least the UDP-Lite header must be covered by the
-         checksum, therefore, if chksum_len has an illegal
-         value, we generate the checksum over the complete
-         packet to be safe. */
-      chklen_hdr = 0;
-      chklen = q->tot_len;
-    }
-    udphdr->len = htons(chklen_hdr);
-    /* calculate checksum */
-#if CHECKSUM_GEN_UDP
-    udphdr->chksum = inet_chksum_pseudo_partial(q, src_ip, dst_ip,
-      IP_PROTO_UDPLITE, q->tot_len,
-#if !LWIP_CHECKSUM_ON_COPY
-      chklen);
-#else /* !LWIP_CHECKSUM_ON_COPY */
-      (have_chksum ? UDP_HLEN : chklen));
-    if (have_chksum) {
-      u32_t acc;
-      acc = udphdr->chksum + (u16_t)~(chksum);
-      udphdr->chksum = FOLD_U32T(acc);
-    }
-#endif /* !LWIP_CHECKSUM_ON_COPY */
-
-    /* chksum zero must become 0xffff, as zero means 'no checksum' */
-    if (udphdr->chksum == 0x0000) {
-      udphdr->chksum = 0xffff;
-    }
-#endif /* CHECKSUM_GEN_UDP */
-    /* output to IP */
-    LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDPLITE,)\n"));
-#if LWIP_NETIF_HWADDRHINT
-    netif->addr_hint = &(pcb->addr_hint);
-#endif /* LWIP_NETIF_HWADDRHINT*/
-    err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDPLITE, netif);
-#if LWIP_NETIF_HWADDRHINT
-    netif->addr_hint = NULL;
-#endif /* LWIP_NETIF_HWADDRHINT*/
-  } else
-#endif /* LWIP_UDPLITE */
-  {      /* UDP */
-    LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP packet length %"U16_F"\n", q->tot_len));
-    udphdr->len = htons(q->tot_len);
-    /* calculate checksum */
-#if CHECKSUM_GEN_UDP
-    if ((pcb->flags & UDP_FLAGS_NOCHKSUM) == 0) {
-      u16_t udpchksum;
-#if LWIP_CHECKSUM_ON_COPY
-      if (have_chksum) {
-        u32_t acc;
-        udpchksum = inet_chksum_pseudo_partial(q, src_ip, dst_ip, IP_PROTO_UDP,
-          q->tot_len, UDP_HLEN);
-        acc = udpchksum + (u16_t)~(chksum);
-        udpchksum = FOLD_U32T(acc);
-      } else
-#endif /* LWIP_CHECKSUM_ON_COPY */
-      {
-        udpchksum = inet_chksum_pseudo(q, src_ip, dst_ip, IP_PROTO_UDP, q->tot_len);
-      }
-
-      /* chksum zero must become 0xffff, as zero means 'no checksum' */
-      if (udpchksum == 0x0000) {
-        udpchksum = 0xffff;
-      }
-      udphdr->chksum = udpchksum;
-    }
-#endif /* CHECKSUM_GEN_UDP */
-    LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04"X16_F"\n", udphdr->chksum));
-    LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDP,)\n"));
-    /* output to IP */
-#if LWIP_NETIF_HWADDRHINT
-    netif->addr_hint = &(pcb->addr_hint);
-#endif /* LWIP_NETIF_HWADDRHINT*/
-    err = ip_output_if(q, src_ip, dst_ip, pcb->ttl, pcb->tos, IP_PROTO_UDP, netif);
-#if LWIP_NETIF_HWADDRHINT
-    netif->addr_hint = NULL;
-#endif /* LWIP_NETIF_HWADDRHINT*/
-  }
-  /* TODO: must this be increased even if error occured? */
-  snmp_inc_udpoutdatagrams();
-
-  /* did we chain a separate header pbuf earlier? */
-  if (q != p) {
-    /* free the header pbuf */
-    pbuf_free(q);
-    q = NULL;
-    /* p is still referenced by the caller, and will live on */
-  }
-
-  UDP_STATS_INC(udp.xmit);
-  return err;
-}
-
-/**
- * Bind an UDP PCB.
- *
- * @param pcb UDP PCB to be bound with a local address ipaddr and port.
- * @param ipaddr local IP address to bind with. Use IP_ADDR_ANY to
- * bind to all local interfaces.
- * @param port local UDP port to bind with. Use 0 to automatically bind
- * to a random port between UDP_LOCAL_PORT_RANGE_START and
- * UDP_LOCAL_PORT_RANGE_END.
- *
- * ipaddr & port are expected to be in the same byte order as in the pcb.
- *
- * @return lwIP error code.
- * - ERR_OK. Successful. No error occured.
- * - ERR_USE. The specified ipaddr and port are already bound to by
- * another UDP PCB.
- *
- * @see udp_disconnect()
- */
-err_t
-udp_bind(struct udp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
-{
-  struct udp_pcb *ipcb;
-  u8_t rebind;
-
-  LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_bind(ipaddr = "));
-  ip_addr_debug_print(UDP_DEBUG, ipaddr);
-  LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, (", port = %"U16_F")\n", port));
-
-  rebind = 0;
-  /* Check for double bind and rebind of the same pcb */
-  for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
-    /* is this UDP PCB already on active list? */
-    if (pcb == ipcb) {
-      /* pcb may occur at most once in active list */
-      LWIP_ASSERT("rebind == 0", rebind == 0);
-      /* pcb already in list, just rebind */
-      rebind = 1;
-    }
-
-    /* By default, we don't allow to bind to a port that any other udp
-       PCB is alread bound to, unless *all* PCBs with that port have tha
-       REUSEADDR flag set. */
-#if SO_REUSE
-    else if (((pcb->so_options & SOF_REUSEADDR) == 0) &&
-             ((ipcb->so_options & SOF_REUSEADDR) == 0)) {
-#else /* SO_REUSE */
-    /* port matches that of PCB in list and REUSEADDR not set -> reject */
-    else {
-#endif /* SO_REUSE */
-      if ((ipcb->local_port == port) &&
-          /* IP address matches, or one is IP_ADDR_ANY? */
-          (ip_addr_isany(&(ipcb->local_ip)) ||
-           ip_addr_isany(ipaddr) ||
-           ip_addr_cmp(&(ipcb->local_ip), ipaddr))) {
-        /* other PCB already binds to this local IP and port */
-        LWIP_DEBUGF(UDP_DEBUG,
-                    ("udp_bind: local port %"U16_F" already bound by another pcb\n", port));
-        return ERR_USE;
-      }
-    }
-  }
-
-  ip_addr_set(&pcb->local_ip, ipaddr);
-
-  /* no port specified? */
-  if (port == 0) {
-#ifndef UDP_LOCAL_PORT_RANGE_START
-#define UDP_LOCAL_PORT_RANGE_START 4096
-#define UDP_LOCAL_PORT_RANGE_END   0x7fff
-#endif
-    port = UDP_LOCAL_PORT_RANGE_START;
-    ipcb = udp_pcbs;
-    while ((ipcb != NULL) && (port != UDP_LOCAL_PORT_RANGE_END)) {
-      if (ipcb->local_port == port) {
-        /* port is already used by another udp_pcb */
-        port++;
-        /* restart scanning all udp pcbs */
-        ipcb = udp_pcbs;
-      } else {
-        /* go on with next udp pcb */
-        ipcb = ipcb->next;
-      }
-    }
-    if (ipcb != NULL) {
-      /* no more ports available in local range */
-      LWIP_DEBUGF(UDP_DEBUG, ("udp_bind: out of free UDP ports\n"));
-      return ERR_USE;
-    }
-  }
-  pcb->local_port = port;
-  snmp_insert_udpidx_tree(pcb);
-  /* pcb not active yet? */
-  if (rebind == 0) {
-    /* place the PCB on the active list if not already there */
-    pcb->next = udp_pcbs;
-    udp_pcbs = pcb;
-  }
-  LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
-              ("udp_bind: bound to %"U16_F".%"U16_F".%"U16_F".%"U16_F", port %"U16_F"\n",
-               ip4_addr1_16(&pcb->local_ip), ip4_addr2_16(&pcb->local_ip),
-               ip4_addr3_16(&pcb->local_ip), ip4_addr4_16(&pcb->local_ip),
-               pcb->local_port));
-  return ERR_OK;
-}
-/**
- * Connect an UDP PCB.
- *
- * This will associate the UDP PCB with the remote address.
- *
- * @param pcb UDP PCB to be connected with remote address ipaddr and port.
- * @param ipaddr remote IP address to connect with.
- * @param port remote UDP port to connect with.
- *
- * @return lwIP error code
- *
- * ipaddr & port are expected to be in the same byte order as in the pcb.
- *
- * The udp pcb is bound to a random local port if not already bound.
- *
- * @see udp_disconnect()
- */
-err_t
-udp_connect(struct udp_pcb *pcb, ip_addr_t *ipaddr, u16_t port)
-{
-  struct udp_pcb *ipcb;
-
-  if (pcb->local_port == 0) {
-    err_t err = udp_bind(pcb, &pcb->local_ip, pcb->local_port);
-    if (err != ERR_OK) {
-      return err;
-    }
-  }
-
-  ip_addr_set(&pcb->remote_ip, ipaddr);
-  pcb->remote_port = port;
-  pcb->flags |= UDP_FLAGS_CONNECTED;
-/** TODO: this functionality belongs in upper layers */
-#ifdef LWIP_UDP_TODO
-  /* Nail down local IP for netconn_addr()/getsockname() */
-  if (ip_addr_isany(&pcb->local_ip) && !ip_addr_isany(&pcb->remote_ip)) {
-    struct netif *netif;
-
-    if ((netif = ip_route(&(pcb->remote_ip))) == NULL) {
-      LWIP_DEBUGF(UDP_DEBUG, ("udp_connect: No route to 0x%lx\n", pcb->remote_ip.addr));
-      UDP_STATS_INC(udp.rterr);
-      return ERR_RTE;
-    }
-    /** TODO: this will bind the udp pcb locally, to the interface which
-        is used to route output packets to the remote address. However, we
-        might want to accept incoming packets on any interface! */
-    pcb->local_ip = netif->ip_addr;
-  } else if (ip_addr_isany(&pcb->remote_ip)) {
-    pcb->local_ip.addr = 0;
-  }
-#endif
-  LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
-              ("udp_connect: connected to %"U16_F".%"U16_F".%"U16_F".%"U16_F",port %"U16_F"\n",
-               ip4_addr1_16(&pcb->local_ip), ip4_addr2_16(&pcb->local_ip),
-               ip4_addr3_16(&pcb->local_ip), ip4_addr4_16(&pcb->local_ip),
-               pcb->local_port));
-
-  /* Insert UDP PCB into the list of active UDP PCBs. */
-  for (ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
-    if (pcb == ipcb) {
-      /* already on the list, just return */
-      return ERR_OK;
-    }
-  }
-  /* PCB not yet on the list, add PCB now */
-  pcb->next = udp_pcbs;
-  udp_pcbs = pcb;
-  return ERR_OK;
-}
-
-/**
- * Disconnect a UDP PCB
- *
- * @param pcb the udp pcb to disconnect.
- */
-void
-udp_disconnect(struct udp_pcb *pcb)
-{
-  /* reset remote address association */
-  ip_addr_set_any(&pcb->remote_ip);
-  pcb->remote_port = 0;
-  /* mark PCB as unconnected */
-  pcb->flags &= ~UDP_FLAGS_CONNECTED;
-}
-
-/**
- * Set a receive callback for a UDP PCB
- *
- * This callback will be called when receiving a datagram for the pcb.
- *
- * @param pcb the pcb for wich to set the recv callback
- * @param recv function pointer of the callback function
- * @param recv_arg additional argument to pass to the callback function
- */
-void
-udp_recv(struct udp_pcb *pcb, udp_recv_fn recv, void *recv_arg)
-{
-  /* remember recv() callback and user data */
-  pcb->recv = recv;
-  pcb->recv_arg = recv_arg;
-}
-
-/**
- * Remove an UDP PCB.
- *
- * @param pcb UDP PCB to be removed. The PCB is removed from the list of
- * UDP PCB's and the data structure is freed from memory.
- *
- * @see udp_new()
- */
-void
-udp_remove(struct udp_pcb *pcb)
-{
-  struct udp_pcb *pcb2;
-
-  snmp_delete_udpidx_tree(pcb);
-  /* pcb to be removed is first in list? */
-  if (udp_pcbs == pcb) {
-    /* make list start at 2nd pcb */
-    udp_pcbs = udp_pcbs->next;
-    /* pcb not 1st in list */
-  } else {
-    for (pcb2 = udp_pcbs; pcb2 != NULL; pcb2 = pcb2->next) {
-      /* find pcb in udp_pcbs list */
-      if (pcb2->next != NULL && pcb2->next == pcb) {
-        /* remove pcb from list */
-        pcb2->next = pcb->next;
-      }
-    }
-  }
-  memp_free(MEMP_UDP_PCB, pcb);
-}
-
-/**
- * Create a UDP PCB.
- *
- * @return The UDP PCB which was created. NULL if the PCB data structure
- * could not be allocated.
- *
- * @see udp_remove()
- */
-struct udp_pcb *
-udp_new(void)
-{
-  struct udp_pcb *pcb;
-  pcb = (struct udp_pcb *)memp_malloc(MEMP_UDP_PCB);
-  /* could allocate UDP PCB? */
-  if (pcb != NULL) {
-    /* UDP Lite: by initializing to all zeroes, chksum_len is set to 0
-     * which means checksum is generated over the whole datagram per default
-     * (recommended as default by RFC 3828). */
-    /* initialize PCB to all zeroes */
-    memset(pcb, 0, sizeof(struct udp_pcb));
-    pcb->ttl = UDP_TTL;
-  }
-  return pcb;
-}
-
-#if UDP_DEBUG
-/**
- * Print UDP header information for debug purposes.
- *
- * @param udphdr pointer to the udp header in memory.
- */
-void
-udp_debug_print(struct udp_hdr *udphdr)
-{
-  LWIP_DEBUGF(UDP_DEBUG, ("UDP header:\n"));
-  LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
-  LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     %5"U16_F"     | (src port, dest port)\n",
-                          ntohs(udphdr->src), ntohs(udphdr->dest)));
-  LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
-  LWIP_DEBUGF(UDP_DEBUG, ("|     %5"U16_F"     |     0x%04"X16_F"    | (len, chksum)\n",
-                          ntohs(udphdr->len), ntohs(udphdr->chksum)));
-  LWIP_DEBUGF(UDP_DEBUG, ("+-------------------------------+\n"));
-}
-#endif /* UDP_DEBUG */
-
-#endif /* LWIP_UDP */