diff --git a/components/net/lwip/src/api/api_msg.c b/components/net/lwip/src/api/api_msg.c
index 46c9abf297..a4e44c7a9e 100644
--- a/components/net/lwip/src/api/api_msg.c
+++ b/components/net/lwip/src/api/api_msg.c
@@ -1,1243 +1,1248 @@
-/**
- * @file
- * Sequential API Internal 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>
- *
- */
-
-#include "lwip/opt.h"
-
-#if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
-
-#include "lwip/api_msg.h"
-
-#include "lwip/ip.h"
-#include "lwip/udp.h"
-#include "lwip/tcp.h"
-#include "lwip/raw.h"
-
-#include "lwip/memp.h"
-#include "lwip/tcpip.h"
-#include "lwip/igmp.h"
-#include "lwip/dns.h"
-
-#include <string.h>
-
-/* forward declarations */
-#if LWIP_TCP
-static err_t do_writemore(struct netconn *conn);
-static void do_close_internal(struct netconn *conn);
-#endif
-
-#if LWIP_RAW
-/**
- * Receive callback function for RAW netconns.
- * Doesn't 'eat' the packet, only references it and sends it to
- * conn->recvmbox
- *
- * @see raw.h (struct raw_pcb.recv) for parameters and return value
- */
-static u8_t
-recv_raw(void *arg, struct raw_pcb *pcb, struct pbuf *p,
-    struct ip_addr *addr)
-{
-  struct pbuf *q;
-  struct netbuf *buf;
-  struct netconn *conn;
-#if LWIP_SO_RCVBUF
-  int recv_avail;
-#endif /* LWIP_SO_RCVBUF */
-
-  LWIP_UNUSED_ARG(addr);
-  conn = arg;
-
-#if LWIP_SO_RCVBUF
-  SYS_ARCH_GET(conn->recv_avail, recv_avail);
-  if ((conn != NULL) && (conn->recvmbox != SYS_MBOX_NULL) &&
-      ((recv_avail + (int)(p->tot_len)) <= conn->recv_bufsize)) {
-#else  /* LWIP_SO_RCVBUF */
-  if ((conn != NULL) && (conn->recvmbox != SYS_MBOX_NULL)) {
-#endif /* LWIP_SO_RCVBUF */
-    /* copy the whole packet into new pbufs */
-    q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
-    if(q != NULL) {
-      if (pbuf_copy(q, p) != ERR_OK) {
-        pbuf_free(q);
-        q = NULL;
-      }
-    }
-
-    if(q != NULL) {
-      buf = memp_malloc(MEMP_NETBUF);
-      if (buf == NULL) {
-        pbuf_free(q);
-        return 0;
-      }
-
-      buf->p = q;
-      buf->ptr = q;
-      buf->addr = &(((struct ip_hdr*)(q->payload))->src);
-      buf->port = pcb->protocol;
-
-      if (sys_mbox_trypost(conn->recvmbox, buf) != ERR_OK) {
-        netbuf_delete(buf);
-        return 0;
-      } else {
-        SYS_ARCH_INC(conn->recv_avail, q->tot_len);
-        /* Register event with callback */
-        API_EVENT(conn, NETCONN_EVT_RCVPLUS, q->tot_len);
-      }
-    }
-  }
-
-  return 0; /* do not eat the packet */
-}
-#endif /* LWIP_RAW*/
-
-#if LWIP_UDP
-/**
- * Receive callback function for UDP netconns.
- * Posts the packet to conn->recvmbox or deletes it on memory error.
- *
- * @see udp.h (struct udp_pcb.recv) for parameters
- */
-static void
-recv_udp(void *arg, struct udp_pcb *pcb, struct pbuf *p,
-   struct ip_addr *addr, u16_t port)
-{
-  struct netbuf *buf;
-  struct netconn *conn;
-#if LWIP_SO_RCVBUF
-  int recv_avail;
-#endif /* LWIP_SO_RCVBUF */
-
-  LWIP_UNUSED_ARG(pcb); /* only used for asserts... */
-  LWIP_ASSERT("recv_udp must have a pcb argument", pcb != NULL);
-  LWIP_ASSERT("recv_udp must have an argument", arg != NULL);
-  conn = arg;
-  LWIP_ASSERT("recv_udp: recv for wrong pcb!", conn->pcb.udp == pcb);
-
-#if LWIP_SO_RCVBUF
-  SYS_ARCH_GET(conn->recv_avail, recv_avail);
-  if ((conn == NULL) || (conn->recvmbox == SYS_MBOX_NULL) ||
-      ((recv_avail + (int)(p->tot_len)) > conn->recv_bufsize)) {
-#else  /* LWIP_SO_RCVBUF */
-  if ((conn == NULL) || (conn->recvmbox == SYS_MBOX_NULL)) {
-#endif /* LWIP_SO_RCVBUF */
-    pbuf_free(p);
-    return;
-  }
-
-  buf = memp_malloc(MEMP_NETBUF);
-  if (buf == NULL) {
-    pbuf_free(p);
-    return;
-  } else {
-    buf->p = p;
-    buf->ptr = p;
-    buf->addr = addr;
-    buf->port = port;
-#if LWIP_NETBUF_RECVINFO
-    {
-      const struct ip_hdr* iphdr = ip_current_header();
-      /* get the UDP header - always in the first pbuf, ensured by udp_input */
-      const struct udp_hdr* udphdr = (void*)(((char*)iphdr) + IPH_LEN(iphdr));
-      buf->toaddr = (struct ip_addr*)&iphdr->dest;
-      buf->toport = udphdr->dest;
-    }
-#endif /* LWIP_NETBUF_RECVINFO */
-  }
-
-  if (sys_mbox_trypost(conn->recvmbox, buf) != ERR_OK) {
-    netbuf_delete(buf);
-    return;
-  } else {
-    SYS_ARCH_INC(conn->recv_avail, p->tot_len);
-    /* Register event with callback */
-    API_EVENT(conn, NETCONN_EVT_RCVPLUS, p->tot_len);
-  }
-}
-#endif /* LWIP_UDP */
-
-#if LWIP_TCP
-/**
- * Receive callback function for TCP netconns.
- * Posts the packet to conn->recvmbox, but doesn't delete it on errors.
- *
- * @see tcp.h (struct tcp_pcb.recv) for parameters and return value
- */
-static err_t
-recv_tcp(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
-{
-  struct netconn *conn;
-  u16_t len;
-
-  LWIP_UNUSED_ARG(pcb);
-  LWIP_ASSERT("recv_tcp must have a pcb argument", pcb != NULL);
-  LWIP_ASSERT("recv_tcp must have an argument", arg != NULL);
-  conn = arg;
-  LWIP_ASSERT("recv_tcp: recv for wrong pcb!", conn->pcb.tcp == pcb);
-
-  if ((conn == NULL) || (conn->recvmbox == SYS_MBOX_NULL)) {
-    return ERR_VAL;
-  }
-
-  conn->err = err;
-  if (p != NULL) {
-    len = p->tot_len;
-    SYS_ARCH_INC(conn->recv_avail, len);
-  } else {
-    len = 0;
-  }
-
-  if (sys_mbox_trypost(conn->recvmbox, p) != ERR_OK) {
-    return ERR_MEM;
-  } else {
-    /* Register event with callback */
-    API_EVENT(conn, NETCONN_EVT_RCVPLUS, len);
-  }
-
-  return ERR_OK;
-}
-
-/**
- * Poll callback function for TCP netconns.
- * Wakes up an application thread that waits for a connection to close
- * or data to be sent. The application thread then takes the
- * appropriate action to go on.
- *
- * Signals the conn->sem.
- * netconn_close waits for conn->sem if closing failed.
- *
- * @see tcp.h (struct tcp_pcb.poll) for parameters and return value
- */
-static err_t
-poll_tcp(void *arg, struct tcp_pcb *pcb)
-{
-  struct netconn *conn = arg;
-
-  LWIP_UNUSED_ARG(pcb);
-  LWIP_ASSERT("conn != NULL", (conn != NULL));
-
-  if (conn->state == NETCONN_WRITE) {
-    do_writemore(conn);
-  } else if (conn->state == NETCONN_CLOSE) {
-    do_close_internal(conn);
-  }
-
-  return ERR_OK;
-}
-
-/**
- * Sent callback function for TCP netconns.
- * Signals the conn->sem and calls API_EVENT.
- * netconn_write waits for conn->sem if send buffer is low.
- *
- * @see tcp.h (struct tcp_pcb.sent) for parameters and return value
- */
-static err_t
-sent_tcp(void *arg, struct tcp_pcb *pcb, u16_t len)
-{
-  struct netconn *conn = arg;
-
-  LWIP_UNUSED_ARG(pcb);
-  LWIP_ASSERT("conn != NULL", (conn != NULL));
-
-  if (conn->state == NETCONN_WRITE) {
-    LWIP_ASSERT("conn->pcb.tcp != NULL", conn->pcb.tcp != NULL);
-    do_writemore(conn);
-  } else if (conn->state == NETCONN_CLOSE) {
-    do_close_internal(conn);
-  }
-
-  if (conn) {
-    if ((conn->pcb.tcp != NULL) && (tcp_sndbuf(conn->pcb.tcp) > TCP_SNDLOWAT)) {
-      API_EVENT(conn, NETCONN_EVT_SENDPLUS, len);
-    }
-  }
-  
-  return ERR_OK;
-}
-
-/**
- * Error callback function for TCP netconns.
- * Signals conn->sem, posts to all conn mboxes and calls API_EVENT.
- * The application thread has then to decide what to do.
- *
- * @see tcp.h (struct tcp_pcb.err) for parameters
- */
-static void
-err_tcp(void *arg, err_t err)
-{
-  struct netconn *conn;
-
-  conn = arg;
-  LWIP_ASSERT("conn != NULL", (conn != NULL));
-
-  conn->pcb.tcp = NULL;
-
-  conn->err = err;
-  if (conn->recvmbox != SYS_MBOX_NULL) {
-    /* Register event with callback */
-    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
-    sys_mbox_post(conn->recvmbox, NULL);
-  }
-  if (conn->op_completed != SYS_SEM_NULL && conn->state == NETCONN_CONNECT) {
-    conn->state = NETCONN_NONE;
-    sys_sem_signal(conn->op_completed);
-  }
-  if (conn->acceptmbox != SYS_MBOX_NULL) {
-    /* Register event with callback */
-    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
-    sys_mbox_post(conn->acceptmbox, NULL);
-  }
-  if ((conn->state == NETCONN_WRITE) || (conn->state == NETCONN_CLOSE)) {
-    /* calling do_writemore/do_close_internal is not necessary
-       since the pcb has already been deleted! */
-    conn->state = NETCONN_NONE;
-    /* wake up the waiting task */
-    sys_sem_signal(conn->op_completed);
-  }
-}
-
-/**
- * Setup a tcp_pcb with the correct callback function pointers
- * and their arguments.
- *
- * @param conn the TCP netconn to setup
- */
-static void
-setup_tcp(struct netconn *conn)
-{
-  struct tcp_pcb *pcb;
-
-  pcb = conn->pcb.tcp;
-  tcp_arg(pcb, conn);
-  tcp_recv(pcb, recv_tcp);
-  tcp_sent(pcb, sent_tcp);
-  tcp_poll(pcb, poll_tcp, 4);
-  tcp_err(pcb, err_tcp);
-}
-
-/**
- * Accept callback function for TCP netconns.
- * Allocates a new netconn and posts that to conn->acceptmbox.
- *
- * @see tcp.h (struct tcp_pcb_listen.accept) for parameters and return value
- */
-static err_t
-accept_function(void *arg, struct tcp_pcb *newpcb, err_t err)
-{
-  struct netconn *newconn;
-  struct netconn *conn;
-
-#if API_MSG_DEBUG
-#if TCP_DEBUG
-  tcp_debug_print_state(newpcb->state);
-#endif /* TCP_DEBUG */
-#endif /* API_MSG_DEBUG */
-  conn = (struct netconn *)arg;
-
-  LWIP_ERROR("accept_function: invalid conn->acceptmbox",
-             conn->acceptmbox != SYS_MBOX_NULL, return ERR_VAL;);
-
-  /* We have to set the callback here even though
-   * the new socket is unknown. conn->socket is marked as -1. */
-  newconn = netconn_alloc(conn->type, conn->callback);
-  if (newconn == NULL) {
-    return ERR_MEM;
-  }
-  newconn->pcb.tcp = newpcb;
-  setup_tcp(newconn);
-  newconn->err = err;
-
-  if (sys_mbox_trypost(conn->acceptmbox, newconn) != ERR_OK) {
-    /* When returning != ERR_OK, the connection is aborted in tcp_process(),
-       so do nothing here! */
-    newconn->pcb.tcp = NULL;
-    netconn_free(newconn);
-    return ERR_MEM;
-  } else {
-    /* Register event with callback */
-    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
-  }
-
-  return ERR_OK;
-}
-#endif /* LWIP_TCP */
-
-/**
- * Create a new pcb of a specific type.
- * Called from do_newconn().
- *
- * @param msg the api_msg_msg describing the connection type
- * @return msg->conn->err, but the return value is currently ignored
- */
-static err_t
-pcb_new(struct api_msg_msg *msg)
-{
-   msg->conn->err = ERR_OK;
-
-   LWIP_ASSERT("pcb_new: pcb already allocated", msg->conn->pcb.tcp == NULL);
-
-   /* Allocate a PCB for this connection */
-   switch(NETCONNTYPE_GROUP(msg->conn->type)) {
-#if LWIP_RAW
-   case NETCONN_RAW:
-     msg->conn->pcb.raw = raw_new(msg->msg.n.proto);
-     if(msg->conn->pcb.raw == NULL) {
-       msg->conn->err = ERR_MEM;
-       break;
-     }
-     raw_recv(msg->conn->pcb.raw, recv_raw, msg->conn);
-     break;
-#endif /* LWIP_RAW */
-#if LWIP_UDP
-   case NETCONN_UDP:
-     msg->conn->pcb.udp = udp_new();
-     if(msg->conn->pcb.udp == NULL) {
-       msg->conn->err = ERR_MEM;
-       break;
-     }
-#if LWIP_UDPLITE
-     if (msg->conn->type==NETCONN_UDPLITE) {
-       udp_setflags(msg->conn->pcb.udp, UDP_FLAGS_UDPLITE);
-     }
-#endif /* LWIP_UDPLITE */
-     if (msg->conn->type==NETCONN_UDPNOCHKSUM) {
-       udp_setflags(msg->conn->pcb.udp, UDP_FLAGS_NOCHKSUM);
-     }
-     udp_recv(msg->conn->pcb.udp, recv_udp, msg->conn);
-     break;
-#endif /* LWIP_UDP */
-#if LWIP_TCP
-   case NETCONN_TCP:
-     msg->conn->pcb.tcp = tcp_new();
-     if(msg->conn->pcb.tcp == NULL) {
-       msg->conn->err = ERR_MEM;
-       break;
-     }
-     setup_tcp(msg->conn);
-     break;
-#endif /* LWIP_TCP */
-   default:
-     /* Unsupported netconn type, e.g. protocol disabled */
-     msg->conn->err = ERR_VAL;
-     break;
-   }
-
-  return msg->conn->err;
-}
-
-/**
- * Create a new pcb of a specific type inside a netconn.
- * Called from netconn_new_with_proto_and_callback.
- *
- * @param msg the api_msg_msg describing the connection type
- */
-void
-do_newconn(struct api_msg_msg *msg)
-{
-   if(msg->conn->pcb.tcp == NULL) {
-     pcb_new(msg);
-   }
-   /* Else? This "new" connection already has a PCB allocated. */
-   /* Is this an error condition? Should it be deleted? */
-   /* We currently just are happy and return. */
-
-   TCPIP_APIMSG_ACK(msg);
-}
-
-/**
- * Create a new netconn (of a specific type) that has a callback function.
- * The corresponding pcb is NOT created!
- *
- * @param t the type of 'connection' to create (@see enum netconn_type)
- * @param proto the IP protocol for RAW IP pcbs
- * @param callback a function to call on status changes (RX available, TX'ed)
- * @return a newly allocated struct netconn or
- *         NULL on memory error
- */
-struct netconn*
-netconn_alloc(enum netconn_type t, netconn_callback callback)
-{
-  struct netconn *conn;
-  int size;
-
-  conn = memp_malloc(MEMP_NETCONN);
-  if (conn == NULL) {
-    return NULL;
-  }
-
-  conn->err = ERR_OK;
-  conn->type = t;
-  conn->pcb.tcp = NULL;
-
-#if (DEFAULT_RAW_RECVMBOX_SIZE == DEFAULT_UDP_RECVMBOX_SIZE) && \
-    (DEFAULT_RAW_RECVMBOX_SIZE == DEFAULT_TCP_RECVMBOX_SIZE)
-  size = DEFAULT_RAW_RECVMBOX_SIZE;
-#else
-  switch(NETCONNTYPE_GROUP(t)) {
-#if LWIP_RAW
-  case NETCONN_RAW:
-    size = DEFAULT_RAW_RECVMBOX_SIZE;
-    break;
-#endif /* LWIP_RAW */
-#if LWIP_UDP
-  case NETCONN_UDP:
-    size = DEFAULT_UDP_RECVMBOX_SIZE;
-    break;
-#endif /* LWIP_UDP */
-#if LWIP_TCP
-  case NETCONN_TCP:
-    size = DEFAULT_TCP_RECVMBOX_SIZE;
-    break;
-#endif /* LWIP_TCP */
-  default:
-    LWIP_ASSERT("netconn_alloc: undefined netconn_type", 0);
-    break;
-  }
-#endif
-
-  if ((conn->op_completed = sys_sem_new(0)) == SYS_SEM_NULL) {
-    memp_free(MEMP_NETCONN, conn);
-    return NULL;
-  }
-  if ((conn->recvmbox = sys_mbox_new(size)) == SYS_MBOX_NULL) {
-    sys_sem_free(conn->op_completed);
-    memp_free(MEMP_NETCONN, conn);
-    return NULL;
-  }
-
-  conn->acceptmbox   = SYS_MBOX_NULL;
-  conn->state        = NETCONN_NONE;
-  /* initialize socket to -1 since 0 is a valid socket */
-  conn->socket       = -1;
-  conn->callback     = callback;
-  conn->recv_avail   = 0;
-#if LWIP_TCP
-  conn->write_msg    = NULL;
-  conn->write_offset = 0;
-#if LWIP_TCPIP_CORE_LOCKING
-  conn->write_delayed = 0;
-#endif /* LWIP_TCPIP_CORE_LOCKING */
-#endif /* LWIP_TCP */
-#if LWIP_SO_RCVTIMEO
-  conn->recv_timeout = 0;
-#endif /* LWIP_SO_RCVTIMEO */
-#if LWIP_SO_RCVBUF
-  conn->recv_bufsize = RECV_BUFSIZE_DEFAULT;
-#endif /* LWIP_SO_RCVBUF */
-  return conn;
-}
-
-/**
- * Delete a netconn and all its resources.
- * The pcb is NOT freed (since we might not be in the right thread context do this).
- *
- * @param conn the netconn to free
- */
-void
-netconn_free(struct netconn *conn)
-{
-  void *mem;
-  LWIP_ASSERT("PCB must be deallocated outside this function", conn->pcb.tcp == NULL);
-
-  /* Drain the recvmbox. */
-  if (conn->recvmbox != SYS_MBOX_NULL) {
-    while (sys_mbox_tryfetch(conn->recvmbox, &mem) != SYS_MBOX_EMPTY) {
-      if (conn->type == NETCONN_TCP) {
-        if(mem != NULL) {
-          pbuf_free((struct pbuf *)mem);
-        }
-      } else {
-        netbuf_delete((struct netbuf *)mem);
-      }
-    }
-    sys_mbox_free(conn->recvmbox);
-    conn->recvmbox = SYS_MBOX_NULL;
-  }
-
-  /* Drain the acceptmbox. */
-  if (conn->acceptmbox != SYS_MBOX_NULL) {
-    while (sys_mbox_tryfetch(conn->acceptmbox, &mem) != SYS_MBOX_EMPTY) {
-      netconn_delete((struct netconn *)mem);
-    }
-    sys_mbox_free(conn->acceptmbox);
-    conn->acceptmbox = SYS_MBOX_NULL;
-  }
-
-  sys_sem_free(conn->op_completed);
-  conn->op_completed = SYS_SEM_NULL;
-
-  memp_free(MEMP_NETCONN, conn);
-}
-
-#if LWIP_TCP
-/**
- * Internal helper function to close a TCP netconn: since this sometimes
- * doesn't work at the first attempt, this function is called from multiple
- * places.
- *
- * @param conn the TCP netconn to close
- */
-static void
-do_close_internal(struct netconn *conn)
-{
-  err_t err;
-
-  LWIP_ASSERT("invalid conn", (conn != NULL));
-  LWIP_ASSERT("this is for tcp netconns only", (conn->type == NETCONN_TCP));
-  LWIP_ASSERT("conn must be in state NETCONN_CLOSE", (conn->state == NETCONN_CLOSE));
-  LWIP_ASSERT("pcb already closed", (conn->pcb.tcp != NULL));
-
-  /* Set back some callback pointers */
-  tcp_arg(conn->pcb.tcp, NULL);
-  if (conn->pcb.tcp->state == LISTEN) {
-    tcp_accept(conn->pcb.tcp, NULL);
-  } else {
-    tcp_recv(conn->pcb.tcp, NULL);
-    tcp_accept(conn->pcb.tcp, NULL);
-    /* some callbacks have to be reset if tcp_close is not successful */
-    tcp_sent(conn->pcb.tcp, NULL);
-    tcp_poll(conn->pcb.tcp, NULL, 4);
-    tcp_err(conn->pcb.tcp, NULL);
-  }
-  /* Try to close the connection */
-  err = tcp_close(conn->pcb.tcp);
-  if (err == ERR_OK) {
-    /* Closing succeeded */
-    conn->state = NETCONN_NONE;
-    /* Set back some callback pointers as conn is going away */
-    conn->pcb.tcp = NULL;
-    conn->err = ERR_OK;
-    /* Trigger select() in socket layer. This send should something else so the
-       errorfd is set, not the read and write fd! */
-    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
-    API_EVENT(conn, NETCONN_EVT_SENDPLUS, 0);
-    /* wake up the application task */
-    sys_sem_signal(conn->op_completed);
-  } else {
-    /* Closing failed, restore some of the callbacks */
-    /* Closing of listen pcb will never fail! */
-    LWIP_ASSERT("Closing a listen pcb may not fail!", (conn->pcb.tcp->state != LISTEN));
-    tcp_sent(conn->pcb.tcp, sent_tcp);
-    tcp_poll(conn->pcb.tcp, poll_tcp, 4);
-    tcp_err(conn->pcb.tcp, err_tcp);
-    tcp_arg(conn->pcb.tcp, conn);
-  }
-  /* If closing didn't succeed, we get called again either
-     from poll_tcp or from sent_tcp */
-}
-#endif /* LWIP_TCP */
-
-/**
- * Delete the pcb inside a netconn.
- * Called from netconn_delete.
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_delconn(struct api_msg_msg *msg)
-{
-  if (msg->conn->pcb.tcp != NULL) {
-    switch (NETCONNTYPE_GROUP(msg->conn->type)) {
-#if LWIP_RAW
-    case NETCONN_RAW:
-      raw_remove(msg->conn->pcb.raw);
-      break;
-#endif /* LWIP_RAW */
-#if LWIP_UDP
-    case NETCONN_UDP:
-      msg->conn->pcb.udp->recv_arg = NULL;
-      udp_remove(msg->conn->pcb.udp);
-      break;
-#endif /* LWIP_UDP */
-#if LWIP_TCP
-    case NETCONN_TCP:
-      msg->conn->state = NETCONN_CLOSE;
-      do_close_internal(msg->conn);
-      /* API_EVENT is called inside do_close_internal, before releasing
-         the application thread, so we can return at this point! */
-      return;
-#endif /* LWIP_TCP */
-    default:
-      break;
-    }
-  }
-  /* tcp netconns don't come here! */
-
-  /* Trigger select() in socket layer. This send should something else so the
-     errorfd is set, not the read and write fd! */
-  API_EVENT(msg->conn, NETCONN_EVT_RCVPLUS, 0);
-  API_EVENT(msg->conn, NETCONN_EVT_SENDPLUS, 0);
-
-  if (msg->conn->op_completed != SYS_SEM_NULL) {
-    sys_sem_signal(msg->conn->op_completed);
-  }
-}
-
-/**
- * Bind a pcb contained in a netconn
- * Called from netconn_bind.
- *
- * @param msg the api_msg_msg pointing to the connection and containing
- *            the IP address and port to bind to
- */
-void
-do_bind(struct api_msg_msg *msg)
-{
-  if (!ERR_IS_FATAL(msg->conn->err)) {
-    if (msg->conn->pcb.tcp != NULL) {
-      switch (NETCONNTYPE_GROUP(msg->conn->type)) {
-#if LWIP_RAW
-      case NETCONN_RAW:
-        msg->conn->err = raw_bind(msg->conn->pcb.raw, msg->msg.bc.ipaddr);
-        break;
-#endif /* LWIP_RAW */
-#if LWIP_UDP
-      case NETCONN_UDP:
-        msg->conn->err = udp_bind(msg->conn->pcb.udp, msg->msg.bc.ipaddr, msg->msg.bc.port);
-        break;
-#endif /* LWIP_UDP */
-#if LWIP_TCP
-      case NETCONN_TCP:
-        msg->conn->err = tcp_bind(msg->conn->pcb.tcp, msg->msg.bc.ipaddr, msg->msg.bc.port);
-        break;
-#endif /* LWIP_TCP */
-      default:
-        break;
-      }
-    } else {
-      /* msg->conn->pcb is NULL */
-      msg->conn->err = ERR_VAL;
-    }
-  }
-  TCPIP_APIMSG_ACK(msg);
-}
-
-#if LWIP_TCP
-/**
- * TCP callback function if a connection (opened by tcp_connect/do_connect) has
- * been established (or reset by the remote host).
- *
- * @see tcp.h (struct tcp_pcb.connected) for parameters and return values
- */
-static err_t
-do_connected(void *arg, struct tcp_pcb *pcb, err_t err)
-{
-  struct netconn *conn;
-
-  LWIP_UNUSED_ARG(pcb);
-
-  conn = arg;
-
-  if (conn == NULL) {
-    return ERR_VAL;
-  }
-
-  conn->err = err;
-  if ((conn->type == NETCONN_TCP) && (err == ERR_OK)) {
-    setup_tcp(conn);
-  }
-  conn->state = NETCONN_NONE;
-  sys_sem_signal(conn->op_completed);
-  return ERR_OK;
-}
-#endif /* LWIP_TCP */
-
-/**
- * Connect a pcb contained inside a netconn
- * Called from netconn_connect.
- *
- * @param msg the api_msg_msg pointing to the connection and containing
- *            the IP address and port to connect to
- */
-void
-do_connect(struct api_msg_msg *msg)
-{
-  if (msg->conn->pcb.tcp == NULL) {
-    sys_sem_signal(msg->conn->op_completed);
-    return;
-  }
-
-  switch (NETCONNTYPE_GROUP(msg->conn->type)) {
-#if LWIP_RAW
-  case NETCONN_RAW:
-    msg->conn->err = raw_connect(msg->conn->pcb.raw, msg->msg.bc.ipaddr);
-    sys_sem_signal(msg->conn->op_completed);
-    break;
-#endif /* LWIP_RAW */
-#if LWIP_UDP
-  case NETCONN_UDP:
-    msg->conn->err = udp_connect(msg->conn->pcb.udp, msg->msg.bc.ipaddr, msg->msg.bc.port);
-    sys_sem_signal(msg->conn->op_completed);
-    break;
-#endif /* LWIP_UDP */
-#if LWIP_TCP
-  case NETCONN_TCP:
-    msg->conn->state = NETCONN_CONNECT;
-    setup_tcp(msg->conn);
-    msg->conn->err = tcp_connect(msg->conn->pcb.tcp, msg->msg.bc.ipaddr, msg->msg.bc.port,
-                                 do_connected);
-    /* sys_sem_signal() is called from do_connected (or err_tcp()),
-     * when the connection is established! */
-    break;
-#endif /* LWIP_TCP */
-  default:
-    LWIP_ERROR("Invalid netconn type", 0, do{ msg->conn->err = ERR_VAL;
-      sys_sem_signal(msg->conn->op_completed); }while(0));
-    break;
-  }
-}
-
-/**
- * Connect a pcb contained inside a netconn
- * Only used for UDP netconns.
- * Called from netconn_disconnect.
- *
- * @param msg the api_msg_msg pointing to the connection to disconnect
- */
-void
-do_disconnect(struct api_msg_msg *msg)
-{
-#if LWIP_UDP
-  if (NETCONNTYPE_GROUP(msg->conn->type) == NETCONN_UDP) {
-    udp_disconnect(msg->conn->pcb.udp);
-  }
-#endif /* LWIP_UDP */
-  TCPIP_APIMSG_ACK(msg);
-}
-
-/**
- * Set a TCP pcb contained in a netconn into listen mode
- * Called from netconn_listen.
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_listen(struct api_msg_msg *msg)
-{
-#if LWIP_TCP
-  if (!ERR_IS_FATAL(msg->conn->err)) {
-    if (msg->conn->pcb.tcp != NULL) {
-      if (msg->conn->type == NETCONN_TCP) {
-        if (msg->conn->pcb.tcp->state == CLOSED) {
-#if TCP_LISTEN_BACKLOG
-          struct tcp_pcb* lpcb = tcp_listen_with_backlog(msg->conn->pcb.tcp, msg->msg.lb.backlog);
-#else  /* TCP_LISTEN_BACKLOG */
-          struct tcp_pcb* lpcb = tcp_listen(msg->conn->pcb.tcp);
-#endif /* TCP_LISTEN_BACKLOG */
-          if (lpcb == NULL) {
-            msg->conn->err = ERR_MEM;
-          } else {
-            /* delete the recvmbox and allocate the acceptmbox */
-            if (msg->conn->recvmbox != SYS_MBOX_NULL) {
-              /** @todo: should we drain the recvmbox here? */
-              sys_mbox_free(msg->conn->recvmbox);
-              msg->conn->recvmbox = SYS_MBOX_NULL;
-            }
-            if (msg->conn->acceptmbox == SYS_MBOX_NULL) {
-              if ((msg->conn->acceptmbox = sys_mbox_new(DEFAULT_ACCEPTMBOX_SIZE)) == SYS_MBOX_NULL) {
-                msg->conn->err = ERR_MEM;
-              }
-            }
-            if (msg->conn->err == ERR_OK) {
-              msg->conn->state = NETCONN_LISTEN;
-              msg->conn->pcb.tcp = lpcb;
-              tcp_arg(msg->conn->pcb.tcp, msg->conn);
-              tcp_accept(msg->conn->pcb.tcp, accept_function);
-            }
-          }
-        } else {
-          msg->conn->err = ERR_CONN;
-        }
-      }
-    }
-  }
-#endif /* LWIP_TCP */
-  TCPIP_APIMSG_ACK(msg);
-}
-
-/**
- * Send some data on a RAW or UDP pcb contained in a netconn
- * Called from netconn_send
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_send(struct api_msg_msg *msg)
-{
-  if (!ERR_IS_FATAL(msg->conn->err)) {
-    if (msg->conn->pcb.tcp != NULL) {
-      switch (NETCONNTYPE_GROUP(msg->conn->type)) {
-#if LWIP_RAW
-      case NETCONN_RAW:
-        if (msg->msg.b->addr == NULL) {
-          msg->conn->err = raw_send(msg->conn->pcb.raw, msg->msg.b->p);
-        } else {
-          msg->conn->err = raw_sendto(msg->conn->pcb.raw, msg->msg.b->p, msg->msg.b->addr);
-        }
-        break;
-#endif
-#if LWIP_UDP
-      case NETCONN_UDP:
-        if (msg->msg.b->addr == NULL) {
-          msg->conn->err = udp_send(msg->conn->pcb.udp, msg->msg.b->p);
-        } else {
-          msg->conn->err = udp_sendto(msg->conn->pcb.udp, msg->msg.b->p, msg->msg.b->addr, msg->msg.b->port);
-        }
-        break;
-#endif /* LWIP_UDP */
-      default:
-        break;
-      }
-    }
-  }
-  TCPIP_APIMSG_ACK(msg);
-}
-
-/**
- * Indicate data has been received from a TCP pcb contained in a netconn
- * Called from netconn_recv
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_recv(struct api_msg_msg *msg)
-{
-#if LWIP_TCP
-  if (!ERR_IS_FATAL(msg->conn->err)) {
-    if (msg->conn->pcb.tcp != NULL) {
-      if (msg->conn->type == NETCONN_TCP) {
-#if TCP_LISTEN_BACKLOG
-        if (msg->conn->pcb.tcp->state == LISTEN) {
-          tcp_accepted(msg->conn->pcb.tcp);
-        } else
-#endif /* TCP_LISTEN_BACKLOG */
-        {
-          tcp_recved(msg->conn->pcb.tcp, msg->msg.r.len);
-        }
-      }
-    }
-  }
-#endif /* LWIP_TCP */
-  TCPIP_APIMSG_ACK(msg);
-}
-
-#if LWIP_TCP
-/**
- * See if more data needs to be written from a previous call to netconn_write.
- * Called initially from do_write. If the first call can't send all data
- * (because of low memory or empty send-buffer), this function is called again
- * from sent_tcp() or poll_tcp() to send more data. If all data is sent, the
- * blocking application thread (waiting in netconn_write) is released.
- *
- * @param conn netconn (that is currently in state NETCONN_WRITE) to process
- * @return ERR_OK
- *         ERR_MEM if LWIP_TCPIP_CORE_LOCKING=1 and sending hasn't yet finished
- */
-static err_t
-do_writemore(struct netconn *conn)
-{
-  err_t err;
-  void *dataptr;
-  u16_t len, available;
-  u8_t write_finished = 0;
-  size_t diff;
-
-  LWIP_ASSERT("conn->state == NETCONN_WRITE", (conn->state == NETCONN_WRITE));
-
-  dataptr = (u8_t*)conn->write_msg->msg.w.dataptr + conn->write_offset;
-  diff = conn->write_msg->msg.w.len - conn->write_offset;
-  if (diff > 0xffffUL) { /* max_u16_t */
-    len = 0xffff;
-#if LWIP_TCPIP_CORE_LOCKING
-    conn->write_delayed = 1;
-#endif
-  } else {
-    len = (u16_t)diff;
-  }
-  available = tcp_sndbuf(conn->pcb.tcp);
-  if (available < len) {
-    /* don't try to write more than sendbuf */
-    len = available;
-#if LWIP_TCPIP_CORE_LOCKING
-    conn->write_delayed = 1;
-#endif
-  }
-
-  err = tcp_write(conn->pcb.tcp, dataptr, len, conn->write_msg->msg.w.apiflags);
-  LWIP_ASSERT("do_writemore: invalid length!", ((conn->write_offset + len) <= conn->write_msg->msg.w.len));
-  if (err == ERR_OK) {
-    conn->write_offset += len;
-    if (conn->write_offset == conn->write_msg->msg.w.len) {
-      /* everything was written */
-      write_finished = 1;
-      conn->write_msg = NULL;
-      conn->write_offset = 0;
-      /* API_EVENT might call tcp_tmr, so reset conn->state now */
-      conn->state = NETCONN_NONE;
-    }
-    err = tcp_output_nagle(conn->pcb.tcp);
-    conn->err = err;
-    if ((err == ERR_OK) && (tcp_sndbuf(conn->pcb.tcp) <= TCP_SNDLOWAT)) {
-      API_EVENT(conn, NETCONN_EVT_SENDMINUS, len);
-    }
-  } else if (err == ERR_MEM) {
-    /* If ERR_MEM, we wait for sent_tcp or poll_tcp to be called
-       we do NOT return to the application thread, since ERR_MEM is
-       only a temporary error! */
-
-    /* tcp_enqueue returned ERR_MEM, try tcp_output anyway */
-    err = tcp_output(conn->pcb.tcp);
-
-#if LWIP_TCPIP_CORE_LOCKING
-    conn->write_delayed = 1;
-#endif
-  } else {
-    /* On errors != ERR_MEM, we don't try writing any more but return
-       the error to the application thread. */
-    conn->err = err;
-    write_finished = 1;
-  }
-
-  if (write_finished) {
-    /* everything was written: set back connection state
-       and back to application task */
-    conn->state = NETCONN_NONE;
-#if LWIP_TCPIP_CORE_LOCKING
-    if (conn->write_delayed != 0)
-#endif
-    {
-      sys_sem_signal(conn->op_completed);
-    }
-  }
-#if LWIP_TCPIP_CORE_LOCKING
-  else
-    return ERR_MEM;
-#endif
-  return ERR_OK;
-}
-#endif /* LWIP_TCP */
-
-/**
- * Send some data on a TCP pcb contained in a netconn
- * Called from netconn_write
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_write(struct api_msg_msg *msg)
-{
-  if (!ERR_IS_FATAL(msg->conn->err)) {
-    if ((msg->conn->pcb.tcp != NULL) && (msg->conn->type == NETCONN_TCP)) {
-#if LWIP_TCP
-      msg->conn->state = NETCONN_WRITE;
-      /* set all the variables used by do_writemore */
-      LWIP_ASSERT("already writing", msg->conn->write_msg == NULL &&
-        msg->conn->write_offset == 0);
-      msg->conn->write_msg = msg;
-      msg->conn->write_offset = 0;
-#if LWIP_TCPIP_CORE_LOCKING
-      msg->conn->write_delayed = 0;
-      if (do_writemore(msg->conn) != ERR_OK) {
-        LWIP_ASSERT("state!", msg->conn->state == NETCONN_WRITE);
-        UNLOCK_TCPIP_CORE();
-        sys_arch_sem_wait(msg->conn->op_completed, 0);
-        LOCK_TCPIP_CORE();
-        LWIP_ASSERT("state!", msg->conn->state == NETCONN_NONE);
-      }
-#else
-      do_writemore(msg->conn);
-#endif
-      /* for both cases: if do_writemore was called, don't ACK the APIMSG! */
-      return;
-#endif /* LWIP_TCP */
-#if (LWIP_UDP || LWIP_RAW)
-    } else {
-      msg->conn->err = ERR_VAL;
-#endif /* (LWIP_UDP || LWIP_RAW) */
-    }
-  }
-  TCPIP_APIMSG_ACK(msg);
-}
-
-/**
- * Return a connection's local or remote address
- * Called from netconn_getaddr
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_getaddr(struct api_msg_msg *msg)
-{
-  if (msg->conn->pcb.ip != NULL) {
-    *(msg->msg.ad.ipaddr) = (msg->msg.ad.local?msg->conn->pcb.ip->local_ip:msg->conn->pcb.ip->remote_ip);
-    
-    switch (NETCONNTYPE_GROUP(msg->conn->type)) {
-#if LWIP_RAW
-    case NETCONN_RAW:
-      if (msg->msg.ad.local) {
-        *(msg->msg.ad.port) = msg->conn->pcb.raw->protocol;
-      } else {
-        /* return an error as connecting is only a helper for upper layers */
-        msg->conn->err = ERR_CONN;
-      }
-      break;
-#endif /* LWIP_RAW */
-#if LWIP_UDP
-    case NETCONN_UDP:
-      if (msg->msg.ad.local) {
-        *(msg->msg.ad.port) = msg->conn->pcb.udp->local_port;
-      } else {
-        if ((msg->conn->pcb.udp->flags & UDP_FLAGS_CONNECTED) == 0) {
-          msg->conn->err = ERR_CONN;
-        } else {
-          *(msg->msg.ad.port) = msg->conn->pcb.udp->remote_port;
-        }
-      }
-      break;
-#endif /* LWIP_UDP */
-#if LWIP_TCP
-    case NETCONN_TCP:
-      *(msg->msg.ad.port) = (msg->msg.ad.local?msg->conn->pcb.tcp->local_port:msg->conn->pcb.tcp->remote_port);
-      break;
-#endif /* LWIP_TCP */
-    }
-  } else {
-    msg->conn->err = ERR_CONN;
-  }
-  TCPIP_APIMSG_ACK(msg);
-}
-
-/**
- * Close a TCP pcb contained in a netconn
- * Called from netconn_close
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_close(struct api_msg_msg *msg)
-{
-#if LWIP_TCP
-  if ((msg->conn->pcb.tcp != NULL) && (msg->conn->type == NETCONN_TCP)) {
-      msg->conn->state = NETCONN_CLOSE;
-      do_close_internal(msg->conn);
-      /* for tcp netconns, do_close_internal ACKs the message */
-  } else
-#endif /* LWIP_TCP */
-  {
-    msg->conn->err = ERR_VAL;
-    sys_sem_signal(msg->conn->op_completed);
-  }
-}
-
-#if LWIP_IGMP
-/**
- * Join multicast groups for UDP netconns.
- * Called from netconn_join_leave_group
- *
- * @param msg the api_msg_msg pointing to the connection
- */
-void
-do_join_leave_group(struct api_msg_msg *msg)
-{ 
-  if (!ERR_IS_FATAL(msg->conn->err)) {
-    if (msg->conn->pcb.tcp != NULL) {
-      if (NETCONNTYPE_GROUP(msg->conn->type) == NETCONN_UDP) {
-#if LWIP_UDP
-        if (msg->msg.jl.join_or_leave == NETCONN_JOIN) {
-          msg->conn->err = igmp_joingroup(msg->msg.jl.interface, msg->msg.jl.multiaddr);
-        } else {
-          msg->conn->err = igmp_leavegroup(msg->msg.jl.interface, msg->msg.jl.multiaddr);
-        }
-#endif /* LWIP_UDP */
-#if (LWIP_TCP || LWIP_RAW)
-      } else {
-        msg->conn->err = ERR_VAL;
-#endif /* (LWIP_TCP || LWIP_RAW) */
-      }
-    }
-  }
-  TCPIP_APIMSG_ACK(msg);
-}
-#endif /* LWIP_IGMP */
-
-#if LWIP_DNS
-/**
- * Callback function that is called when DNS name is resolved
- * (or on timeout). A waiting application thread is waked up by
- * signaling the semaphore.
- */
-static void
-do_dns_found(const char *name, struct ip_addr *ipaddr, void *arg)
-{
-  struct dns_api_msg *msg = (struct dns_api_msg*)arg;
-
-  LWIP_ASSERT("DNS response for wrong host name", strcmp(msg->name, name) == 0);
-
-  if (ipaddr == NULL) {
-    /* timeout or memory error */
-    *msg->err = ERR_VAL;
-  } else {
-    /* address was resolved */
-    *msg->err = ERR_OK;
-    *msg->addr = *ipaddr;
-  }
-  /* wake up the application task waiting in netconn_gethostbyname */
-  sys_sem_signal(msg->sem);
-}
-
-/**
- * Execute a DNS query
- * Called from netconn_gethostbyname
- *
- * @param arg the dns_api_msg pointing to the query
- */
-void
-do_gethostbyname(void *arg)
-{
-  struct dns_api_msg *msg = (struct dns_api_msg*)arg;
-
-  *msg->err = dns_gethostbyname(msg->name, msg->addr, do_dns_found, msg);
-  if (*msg->err != ERR_INPROGRESS) {
-    /* on error or immediate success, wake up the application
-     * task waiting in netconn_gethostbyname */
-    sys_sem_signal(msg->sem);
-  }
-}
-#endif /* LWIP_DNS */
-
-#endif /* LWIP_NETCONN */
+/**
+ * @file
+ * Sequential API Internal 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>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
+
+#include "lwip/api_msg.h"
+
+#include "lwip/ip.h"
+#include "lwip/udp.h"
+#include "lwip/tcp.h"
+#include "lwip/raw.h"
+
+#include "lwip/memp.h"
+#include "lwip/tcpip.h"
+#include "lwip/igmp.h"
+#include "lwip/dns.h"
+
+#include <string.h>
+
+/* forward declarations */
+#if LWIP_TCP
+static err_t do_writemore(struct netconn *conn);
+static void do_close_internal(struct netconn *conn);
+#endif
+
+#if LWIP_RAW
+/**
+ * Receive callback function for RAW netconns.
+ * Doesn't 'eat' the packet, only references it and sends it to
+ * conn->recvmbox
+ *
+ * @see raw.h (struct raw_pcb.recv) for parameters and return value
+ */
+static u8_t
+recv_raw(void *arg, struct raw_pcb *pcb, struct pbuf *p,
+    struct ip_addr *addr)
+{
+  struct pbuf *q;
+  struct netbuf *buf;
+  struct netconn *conn;
+#if LWIP_SO_RCVBUF
+  int recv_avail;
+#endif /* LWIP_SO_RCVBUF */
+
+  LWIP_UNUSED_ARG(addr);
+  conn = arg;
+
+#if LWIP_SO_RCVBUF
+  SYS_ARCH_GET(conn->recv_avail, recv_avail);
+  if ((conn != NULL) && (conn->recvmbox != SYS_MBOX_NULL) &&
+      ((recv_avail + (int)(p->tot_len)) <= conn->recv_bufsize)) {
+#else  /* LWIP_SO_RCVBUF */
+  if ((conn != NULL) && (conn->recvmbox != SYS_MBOX_NULL)) {
+#endif /* LWIP_SO_RCVBUF */
+    /* copy the whole packet into new pbufs */
+    q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
+    if(q != NULL) {
+      if (pbuf_copy(q, p) != ERR_OK) {
+        pbuf_free(q);
+        q = NULL;
+      }
+    }
+
+    if(q != NULL) {
+      buf = memp_malloc(MEMP_NETBUF);
+      if (buf == NULL) {
+        pbuf_free(q);
+        return 0;
+      }
+
+      buf->p = q;
+      buf->ptr = q;
+      buf->addr = &(((struct ip_hdr*)(q->payload))->src);
+      buf->port = pcb->protocol;
+
+      if (sys_mbox_trypost(conn->recvmbox, buf) != ERR_OK) {
+        netbuf_delete(buf);
+        return 0;
+      } else {
+        SYS_ARCH_INC(conn->recv_avail, q->tot_len);
+        /* Register event with callback */
+        API_EVENT(conn, NETCONN_EVT_RCVPLUS, q->tot_len);
+      }
+    }
+  }
+
+  return 0; /* do not eat the packet */
+}
+#endif /* LWIP_RAW*/
+
+#if LWIP_UDP
+/**
+ * Receive callback function for UDP netconns.
+ * Posts the packet to conn->recvmbox or deletes it on memory error.
+ *
+ * @see udp.h (struct udp_pcb.recv) for parameters
+ */
+static void
+recv_udp(void *arg, struct udp_pcb *pcb, struct pbuf *p,
+   struct ip_addr *addr, u16_t port)
+{
+  struct netbuf *buf;
+  struct netconn *conn;
+#if LWIP_SO_RCVBUF
+  int recv_avail;
+#endif /* LWIP_SO_RCVBUF */
+
+  LWIP_UNUSED_ARG(pcb); /* only used for asserts... */
+  LWIP_ASSERT("recv_udp must have a pcb argument", pcb != NULL);
+  LWIP_ASSERT("recv_udp must have an argument", arg != NULL);
+  conn = arg;
+  LWIP_ASSERT("recv_udp: recv for wrong pcb!", conn->pcb.udp == pcb);
+
+#if LWIP_SO_RCVBUF
+  SYS_ARCH_GET(conn->recv_avail, recv_avail);
+  if ((conn == NULL) || (conn->recvmbox == SYS_MBOX_NULL) ||
+      ((recv_avail + (int)(p->tot_len)) > conn->recv_bufsize)) {
+#else  /* LWIP_SO_RCVBUF */
+  if ((conn == NULL) || (conn->recvmbox == SYS_MBOX_NULL)) {
+#endif /* LWIP_SO_RCVBUF */
+    pbuf_free(p);
+    return;
+  }
+
+  buf = memp_malloc(MEMP_NETBUF);
+  if (buf == NULL) {
+    pbuf_free(p);
+    return;
+  } else {
+    buf->p = p;
+    buf->ptr = p;
+    buf->addr = addr;
+    buf->port = port;
+#if LWIP_NETBUF_RECVINFO
+    {
+      const struct ip_hdr* iphdr = ip_current_header();
+      /* get the UDP header - always in the first pbuf, ensured by udp_input */
+      const struct udp_hdr* udphdr = (void*)(((char*)iphdr) + IPH_LEN(iphdr));
+      buf->toaddr = (struct ip_addr*)&iphdr->dest;
+      buf->toport = udphdr->dest;
+    }
+#endif /* LWIP_NETBUF_RECVINFO */
+  }
+
+  if (sys_mbox_trypost(conn->recvmbox, buf) != ERR_OK) {
+    netbuf_delete(buf);
+    return;
+  } else {
+    SYS_ARCH_INC(conn->recv_avail, p->tot_len);
+    /* Register event with callback */
+    API_EVENT(conn, NETCONN_EVT_RCVPLUS, p->tot_len);
+  }
+}
+#endif /* LWIP_UDP */
+
+#if LWIP_TCP
+/**
+ * Receive callback function for TCP netconns.
+ * Posts the packet to conn->recvmbox, but doesn't delete it on errors.
+ *
+ * @see tcp.h (struct tcp_pcb.recv) for parameters and return value
+ */
+static err_t
+recv_tcp(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
+{
+  struct netconn *conn;
+  u16_t len;
+
+  LWIP_UNUSED_ARG(pcb);
+  LWIP_ASSERT("recv_tcp must have a pcb argument", pcb != NULL);
+  LWIP_ASSERT("recv_tcp must have an argument", arg != NULL);
+  conn = arg;
+  LWIP_ASSERT("recv_tcp: recv for wrong pcb!", conn->pcb.tcp == pcb);
+
+  if ((conn == NULL) || (conn->recvmbox == SYS_MBOX_NULL)) {
+    return ERR_VAL;
+  }
+
+  conn->err = err;
+  if (p != NULL) {
+    len = p->tot_len;
+    SYS_ARCH_INC(conn->recv_avail, len);
+  } else {
+    len = 0;
+  }
+
+  if (sys_mbox_trypost(conn->recvmbox, p) != ERR_OK) {
+    return ERR_MEM;
+  } else {
+    /* Register event with callback */
+    API_EVENT(conn, NETCONN_EVT_RCVPLUS, len);
+  }
+
+  return ERR_OK;
+}
+
+/**
+ * Poll callback function for TCP netconns.
+ * Wakes up an application thread that waits for a connection to close
+ * or data to be sent. The application thread then takes the
+ * appropriate action to go on.
+ *
+ * Signals the conn->sem.
+ * netconn_close waits for conn->sem if closing failed.
+ *
+ * @see tcp.h (struct tcp_pcb.poll) for parameters and return value
+ */
+static err_t
+poll_tcp(void *arg, struct tcp_pcb *pcb)
+{
+  struct netconn *conn = arg;
+
+  LWIP_UNUSED_ARG(pcb);
+  LWIP_ASSERT("conn != NULL", (conn != NULL));
+
+  if (conn->state == NETCONN_WRITE) {
+    do_writemore(conn);
+  } else if (conn->state == NETCONN_CLOSE) {
+    do_close_internal(conn);
+  }
+
+  return ERR_OK;
+}
+
+/**
+ * Sent callback function for TCP netconns.
+ * Signals the conn->sem and calls API_EVENT.
+ * netconn_write waits for conn->sem if send buffer is low.
+ *
+ * @see tcp.h (struct tcp_pcb.sent) for parameters and return value
+ */
+static err_t
+sent_tcp(void *arg, struct tcp_pcb *pcb, u16_t len)
+{
+  struct netconn *conn = arg;
+
+  LWIP_UNUSED_ARG(pcb);
+  LWIP_ASSERT("conn != NULL", (conn != NULL));
+
+  if (conn->state == NETCONN_WRITE) {
+    LWIP_ASSERT("conn->pcb.tcp != NULL", conn->pcb.tcp != NULL);
+    do_writemore(conn);
+  } else if (conn->state == NETCONN_CLOSE) {
+    do_close_internal(conn);
+  }
+
+  if (conn) {
+    if ((conn->pcb.tcp != NULL) && (tcp_sndbuf(conn->pcb.tcp) > TCP_SNDLOWAT)) {
+      API_EVENT(conn, NETCONN_EVT_SENDPLUS, len);
+    }
+  }
+  
+  return ERR_OK;
+}
+
+/**
+ * Error callback function for TCP netconns.
+ * Signals conn->sem, posts to all conn mboxes and calls API_EVENT.
+ * The application thread has then to decide what to do.
+ *
+ * @see tcp.h (struct tcp_pcb.err) for parameters
+ */
+static void
+err_tcp(void *arg, err_t err)
+{
+  struct netconn *conn;
+
+  conn = arg;
+  LWIP_ASSERT("conn != NULL", (conn != NULL));
+
+  conn->pcb.tcp = NULL;
+
+  conn->err = err;
+  if (conn->recvmbox != SYS_MBOX_NULL) {
+    /* Register event with callback */
+    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
+    sys_mbox_post(conn->recvmbox, NULL);
+  }
+  if (conn->op_completed != SYS_SEM_NULL && conn->state == NETCONN_CONNECT) {
+    conn->state = NETCONN_NONE;
+    sys_sem_signal(conn->op_completed);
+  }
+  if (conn->acceptmbox != SYS_MBOX_NULL) {
+    /* Register event with callback */
+    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
+    sys_mbox_post(conn->acceptmbox, NULL);
+  }
+  if ((conn->state == NETCONN_WRITE) || (conn->state == NETCONN_CLOSE)) {
+    /* calling do_writemore/do_close_internal is not necessary
+       since the pcb has already been deleted! */
+    conn->state = NETCONN_NONE;
+    /* wake up the waiting task */
+    sys_sem_signal(conn->op_completed);
+  }
+}
+
+/**
+ * Setup a tcp_pcb with the correct callback function pointers
+ * and their arguments.
+ *
+ * @param conn the TCP netconn to setup
+ */
+static void
+setup_tcp(struct netconn *conn)
+{
+  struct tcp_pcb *pcb;
+
+  pcb = conn->pcb.tcp;
+  tcp_arg(pcb, conn);
+  tcp_recv(pcb, recv_tcp);
+  tcp_sent(pcb, sent_tcp);
+  tcp_poll(pcb, poll_tcp, 4);
+  tcp_err(pcb, err_tcp);
+}
+
+/**
+ * Accept callback function for TCP netconns.
+ * Allocates a new netconn and posts that to conn->acceptmbox.
+ *
+ * @see tcp.h (struct tcp_pcb_listen.accept) for parameters and return value
+ */
+static err_t
+accept_function(void *arg, struct tcp_pcb *newpcb, err_t err)
+{
+  struct netconn *newconn;
+  struct netconn *conn;
+
+#if API_MSG_DEBUG
+#if TCP_DEBUG
+  tcp_debug_print_state(newpcb->state);
+#endif /* TCP_DEBUG */
+#endif /* API_MSG_DEBUG */
+  conn = (struct netconn *)arg;
+
+  /* check whether acceptmbox is valid */
+  if (conn->acceptmbox == SYS_MBOX_NULL)
+  {
+    LWIP_DEBUGF(API_MSG_DEBUG, ("accept_function: acceptmbox already deleted\n"));
+	return ERR_VAL;
+  }
+
+  /* We have to set the callback here even though
+   * the new socket is unknown. conn->socket is marked as -1. */
+  newconn = netconn_alloc(conn->type, conn->callback);
+  if (newconn == NULL) {
+    return ERR_MEM;
+  }
+  newconn->pcb.tcp = newpcb;
+  setup_tcp(newconn);
+  newconn->err = err;
+
+  if (sys_mbox_trypost(conn->acceptmbox, newconn) != ERR_OK) {
+    /* When returning != ERR_OK, the connection is aborted in tcp_process(),
+       so do nothing here! */
+    newconn->pcb.tcp = NULL;
+    netconn_free(newconn);
+    return ERR_MEM;
+  } else {
+    /* Register event with callback */
+    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
+  }
+
+  return ERR_OK;
+}
+#endif /* LWIP_TCP */
+
+/**
+ * Create a new pcb of a specific type.
+ * Called from do_newconn().
+ *
+ * @param msg the api_msg_msg describing the connection type
+ * @return msg->conn->err, but the return value is currently ignored
+ */
+static err_t
+pcb_new(struct api_msg_msg *msg)
+{
+   msg->conn->err = ERR_OK;
+
+   LWIP_ASSERT("pcb_new: pcb already allocated", msg->conn->pcb.tcp == NULL);
+
+   /* Allocate a PCB for this connection */
+   switch(NETCONNTYPE_GROUP(msg->conn->type)) {
+#if LWIP_RAW
+   case NETCONN_RAW:
+     msg->conn->pcb.raw = raw_new(msg->msg.n.proto);
+     if(msg->conn->pcb.raw == NULL) {
+       msg->conn->err = ERR_MEM;
+       break;
+     }
+     raw_recv(msg->conn->pcb.raw, recv_raw, msg->conn);
+     break;
+#endif /* LWIP_RAW */
+#if LWIP_UDP
+   case NETCONN_UDP:
+     msg->conn->pcb.udp = udp_new();
+     if(msg->conn->pcb.udp == NULL) {
+       msg->conn->err = ERR_MEM;
+       break;
+     }
+#if LWIP_UDPLITE
+     if (msg->conn->type==NETCONN_UDPLITE) {
+       udp_setflags(msg->conn->pcb.udp, UDP_FLAGS_UDPLITE);
+     }
+#endif /* LWIP_UDPLITE */
+     if (msg->conn->type==NETCONN_UDPNOCHKSUM) {
+       udp_setflags(msg->conn->pcb.udp, UDP_FLAGS_NOCHKSUM);
+     }
+     udp_recv(msg->conn->pcb.udp, recv_udp, msg->conn);
+     break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+   case NETCONN_TCP:
+     msg->conn->pcb.tcp = tcp_new();
+     if(msg->conn->pcb.tcp == NULL) {
+       msg->conn->err = ERR_MEM;
+       break;
+     }
+     setup_tcp(msg->conn);
+     break;
+#endif /* LWIP_TCP */
+   default:
+     /* Unsupported netconn type, e.g. protocol disabled */
+     msg->conn->err = ERR_VAL;
+     break;
+   }
+
+  return msg->conn->err;
+}
+
+/**
+ * Create a new pcb of a specific type inside a netconn.
+ * Called from netconn_new_with_proto_and_callback.
+ *
+ * @param msg the api_msg_msg describing the connection type
+ */
+void
+do_newconn(struct api_msg_msg *msg)
+{
+   if(msg->conn->pcb.tcp == NULL) {
+     pcb_new(msg);
+   }
+   /* Else? This "new" connection already has a PCB allocated. */
+   /* Is this an error condition? Should it be deleted? */
+   /* We currently just are happy and return. */
+
+   TCPIP_APIMSG_ACK(msg);
+}
+
+/**
+ * Create a new netconn (of a specific type) that has a callback function.
+ * The corresponding pcb is NOT created!
+ *
+ * @param t the type of 'connection' to create (@see enum netconn_type)
+ * @param proto the IP protocol for RAW IP pcbs
+ * @param callback a function to call on status changes (RX available, TX'ed)
+ * @return a newly allocated struct netconn or
+ *         NULL on memory error
+ */
+struct netconn*
+netconn_alloc(enum netconn_type t, netconn_callback callback)
+{
+  struct netconn *conn;
+  int size;
+
+  conn = memp_malloc(MEMP_NETCONN);
+  if (conn == NULL) {
+    return NULL;
+  }
+
+  conn->err = ERR_OK;
+  conn->type = t;
+  conn->pcb.tcp = NULL;
+
+#if (DEFAULT_RAW_RECVMBOX_SIZE == DEFAULT_UDP_RECVMBOX_SIZE) && \
+    (DEFAULT_RAW_RECVMBOX_SIZE == DEFAULT_TCP_RECVMBOX_SIZE)
+  size = DEFAULT_RAW_RECVMBOX_SIZE;
+#else
+  size = 0; /* skip warning */
+  switch(NETCONNTYPE_GROUP(t)) {
+#if LWIP_RAW
+  case NETCONN_RAW:
+    size = DEFAULT_RAW_RECVMBOX_SIZE;
+    break;
+#endif /* LWIP_RAW */
+#if LWIP_UDP
+  case NETCONN_UDP:
+    size = DEFAULT_UDP_RECVMBOX_SIZE;
+    break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+  case NETCONN_TCP:
+    size = DEFAULT_TCP_RECVMBOX_SIZE;
+    break;
+#endif /* LWIP_TCP */
+  default:
+    LWIP_ASSERT("netconn_alloc: undefined netconn_type", 0);
+    break;
+  }
+#endif
+
+  if ((conn->op_completed = sys_sem_new(0)) == SYS_SEM_NULL) {
+    memp_free(MEMP_NETCONN, conn);
+    return NULL;
+  }
+  if ((conn->recvmbox = sys_mbox_new(size)) == SYS_MBOX_NULL) {
+    sys_sem_free(conn->op_completed);
+    memp_free(MEMP_NETCONN, conn);
+    return NULL;
+  }
+
+  conn->acceptmbox   = SYS_MBOX_NULL;
+  conn->state        = NETCONN_NONE;
+  /* initialize socket to -1 since 0 is a valid socket */
+  conn->socket       = -1;
+  conn->callback     = callback;
+  conn->recv_avail   = 0;
+#if LWIP_TCP
+  conn->write_msg    = NULL;
+  conn->write_offset = 0;
+#if LWIP_TCPIP_CORE_LOCKING
+  conn->write_delayed = 0;
+#endif /* LWIP_TCPIP_CORE_LOCKING */
+#endif /* LWIP_TCP */
+#if LWIP_SO_RCVTIMEO
+  conn->recv_timeout = 0;
+#endif /* LWIP_SO_RCVTIMEO */
+#if LWIP_SO_RCVBUF
+  conn->recv_bufsize = RECV_BUFSIZE_DEFAULT;
+#endif /* LWIP_SO_RCVBUF */
+  return conn;
+}
+
+/**
+ * Delete a netconn and all its resources.
+ * The pcb is NOT freed (since we might not be in the right thread context do this).
+ *
+ * @param conn the netconn to free
+ */
+void
+netconn_free(struct netconn *conn)
+{
+  void *mem;
+  LWIP_ASSERT("PCB must be deallocated outside this function", conn->pcb.tcp == NULL);
+
+  /* Drain the recvmbox. */
+  if (conn->recvmbox != SYS_MBOX_NULL) {
+    while (sys_mbox_tryfetch(conn->recvmbox, &mem) != SYS_MBOX_EMPTY) {
+      if (conn->type == NETCONN_TCP) {
+        if(mem != NULL) {
+          pbuf_free((struct pbuf *)mem);
+        }
+      } else {
+        netbuf_delete((struct netbuf *)mem);
+      }
+    }
+    sys_mbox_free(conn->recvmbox);
+    conn->recvmbox = SYS_MBOX_NULL;
+  }
+
+  /* Drain the acceptmbox. */
+  if (conn->acceptmbox != SYS_MBOX_NULL) {
+    while (sys_mbox_tryfetch(conn->acceptmbox, &mem) != SYS_MBOX_EMPTY) {
+      netconn_delete((struct netconn *)mem);
+    }
+    sys_mbox_free(conn->acceptmbox);
+    conn->acceptmbox = SYS_MBOX_NULL;
+  }
+
+  sys_sem_free(conn->op_completed);
+  conn->op_completed = SYS_SEM_NULL;
+
+  memp_free(MEMP_NETCONN, conn);
+}
+
+#if LWIP_TCP
+/**
+ * Internal helper function to close a TCP netconn: since this sometimes
+ * doesn't work at the first attempt, this function is called from multiple
+ * places.
+ *
+ * @param conn the TCP netconn to close
+ */
+static void
+do_close_internal(struct netconn *conn)
+{
+  err_t err;
+
+  LWIP_ASSERT("invalid conn", (conn != NULL));
+  LWIP_ASSERT("this is for tcp netconns only", (conn->type == NETCONN_TCP));
+  LWIP_ASSERT("conn must be in state NETCONN_CLOSE", (conn->state == NETCONN_CLOSE));
+  LWIP_ASSERT("pcb already closed", (conn->pcb.tcp != NULL));
+
+  /* Set back some callback pointers */
+  tcp_arg(conn->pcb.tcp, NULL);
+  if (conn->pcb.tcp->state == LISTEN) {
+    tcp_accept(conn->pcb.tcp, NULL);
+  } else {
+    tcp_recv(conn->pcb.tcp, NULL);
+    tcp_accept(conn->pcb.tcp, NULL);
+    /* some callbacks have to be reset if tcp_close is not successful */
+    tcp_sent(conn->pcb.tcp, NULL);
+    tcp_poll(conn->pcb.tcp, NULL, 4);
+    tcp_err(conn->pcb.tcp, NULL);
+  }
+  /* Try to close the connection */
+  err = tcp_close(conn->pcb.tcp);
+  if (err == ERR_OK) {
+    /* Closing succeeded */
+    conn->state = NETCONN_NONE;
+    /* Set back some callback pointers as conn is going away */
+    conn->pcb.tcp = NULL;
+    conn->err = ERR_OK;
+    /* Trigger select() in socket layer. This send should something else so the
+       errorfd is set, not the read and write fd! */
+    API_EVENT(conn, NETCONN_EVT_RCVPLUS, 0);
+    API_EVENT(conn, NETCONN_EVT_SENDPLUS, 0);
+    /* wake up the application task */
+    sys_sem_signal(conn->op_completed);
+  } else {
+    /* Closing failed, restore some of the callbacks */
+    /* Closing of listen pcb will never fail! */
+    LWIP_ASSERT("Closing a listen pcb may not fail!", (conn->pcb.tcp->state != LISTEN));
+    tcp_sent(conn->pcb.tcp, sent_tcp);
+    tcp_poll(conn->pcb.tcp, poll_tcp, 4);
+    tcp_err(conn->pcb.tcp, err_tcp);
+    tcp_arg(conn->pcb.tcp, conn);
+  }
+  /* If closing didn't succeed, we get called again either
+     from poll_tcp or from sent_tcp */
+}
+#endif /* LWIP_TCP */
+
+/**
+ * Delete the pcb inside a netconn.
+ * Called from netconn_delete.
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_delconn(struct api_msg_msg *msg)
+{
+  if (msg->conn->pcb.tcp != NULL) {
+    switch (NETCONNTYPE_GROUP(msg->conn->type)) {
+#if LWIP_RAW
+    case NETCONN_RAW:
+      raw_remove(msg->conn->pcb.raw);
+      break;
+#endif /* LWIP_RAW */
+#if LWIP_UDP
+    case NETCONN_UDP:
+      msg->conn->pcb.udp->recv_arg = NULL;
+      udp_remove(msg->conn->pcb.udp);
+      break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+    case NETCONN_TCP:
+      msg->conn->state = NETCONN_CLOSE;
+      do_close_internal(msg->conn);
+      /* API_EVENT is called inside do_close_internal, before releasing
+         the application thread, so we can return at this point! */
+      return;
+#endif /* LWIP_TCP */
+    default:
+      break;
+    }
+  }
+  /* tcp netconns don't come here! */
+
+  /* Trigger select() in socket layer. This send should something else so the
+     errorfd is set, not the read and write fd! */
+  API_EVENT(msg->conn, NETCONN_EVT_RCVPLUS, 0);
+  API_EVENT(msg->conn, NETCONN_EVT_SENDPLUS, 0);
+
+  if (msg->conn->op_completed != SYS_SEM_NULL) {
+    sys_sem_signal(msg->conn->op_completed);
+  }
+}
+
+/**
+ * Bind a pcb contained in a netconn
+ * Called from netconn_bind.
+ *
+ * @param msg the api_msg_msg pointing to the connection and containing
+ *            the IP address and port to bind to
+ */
+void
+do_bind(struct api_msg_msg *msg)
+{
+  if (!ERR_IS_FATAL(msg->conn->err)) {
+    if (msg->conn->pcb.tcp != NULL) {
+      switch (NETCONNTYPE_GROUP(msg->conn->type)) {
+#if LWIP_RAW
+      case NETCONN_RAW:
+        msg->conn->err = raw_bind(msg->conn->pcb.raw, msg->msg.bc.ipaddr);
+        break;
+#endif /* LWIP_RAW */
+#if LWIP_UDP
+      case NETCONN_UDP:
+        msg->conn->err = udp_bind(msg->conn->pcb.udp, msg->msg.bc.ipaddr, msg->msg.bc.port);
+        break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+      case NETCONN_TCP:
+        msg->conn->err = tcp_bind(msg->conn->pcb.tcp, msg->msg.bc.ipaddr, msg->msg.bc.port);
+        break;
+#endif /* LWIP_TCP */
+      default:
+        break;
+      }
+    } else {
+      /* msg->conn->pcb is NULL */
+      msg->conn->err = ERR_VAL;
+    }
+  }
+  TCPIP_APIMSG_ACK(msg);
+}
+
+#if LWIP_TCP
+/**
+ * TCP callback function if a connection (opened by tcp_connect/do_connect) has
+ * been established (or reset by the remote host).
+ *
+ * @see tcp.h (struct tcp_pcb.connected) for parameters and return values
+ */
+static err_t
+do_connected(void *arg, struct tcp_pcb *pcb, err_t err)
+{
+  struct netconn *conn;
+
+  LWIP_UNUSED_ARG(pcb);
+
+  conn = arg;
+
+  if (conn == NULL) {
+    return ERR_VAL;
+  }
+
+  conn->err = err;
+  if ((conn->type == NETCONN_TCP) && (err == ERR_OK)) {
+    setup_tcp(conn);
+  }
+  conn->state = NETCONN_NONE;
+  sys_sem_signal(conn->op_completed);
+  return ERR_OK;
+}
+#endif /* LWIP_TCP */
+
+/**
+ * Connect a pcb contained inside a netconn
+ * Called from netconn_connect.
+ *
+ * @param msg the api_msg_msg pointing to the connection and containing
+ *            the IP address and port to connect to
+ */
+void
+do_connect(struct api_msg_msg *msg)
+{
+  if (msg->conn->pcb.tcp == NULL) {
+    sys_sem_signal(msg->conn->op_completed);
+    return;
+  }
+
+  switch (NETCONNTYPE_GROUP(msg->conn->type)) {
+#if LWIP_RAW
+  case NETCONN_RAW:
+    msg->conn->err = raw_connect(msg->conn->pcb.raw, msg->msg.bc.ipaddr);
+    sys_sem_signal(msg->conn->op_completed);
+    break;
+#endif /* LWIP_RAW */
+#if LWIP_UDP
+  case NETCONN_UDP:
+    msg->conn->err = udp_connect(msg->conn->pcb.udp, msg->msg.bc.ipaddr, msg->msg.bc.port);
+    sys_sem_signal(msg->conn->op_completed);
+    break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+  case NETCONN_TCP:
+    msg->conn->state = NETCONN_CONNECT;
+    setup_tcp(msg->conn);
+    msg->conn->err = tcp_connect(msg->conn->pcb.tcp, msg->msg.bc.ipaddr, msg->msg.bc.port,
+                                 do_connected);
+    /* sys_sem_signal() is called from do_connected (or err_tcp()),
+     * when the connection is established! */
+    break;
+#endif /* LWIP_TCP */
+  default:
+    LWIP_ERROR("Invalid netconn type", 0, do{ msg->conn->err = ERR_VAL;
+      sys_sem_signal(msg->conn->op_completed); }while(0));
+    break;
+  }
+}
+
+/**
+ * Connect a pcb contained inside a netconn
+ * Only used for UDP netconns.
+ * Called from netconn_disconnect.
+ *
+ * @param msg the api_msg_msg pointing to the connection to disconnect
+ */
+void
+do_disconnect(struct api_msg_msg *msg)
+{
+#if LWIP_UDP
+  if (NETCONNTYPE_GROUP(msg->conn->type) == NETCONN_UDP) {
+    udp_disconnect(msg->conn->pcb.udp);
+  }
+#endif /* LWIP_UDP */
+  TCPIP_APIMSG_ACK(msg);
+}
+
+/**
+ * Set a TCP pcb contained in a netconn into listen mode
+ * Called from netconn_listen.
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_listen(struct api_msg_msg *msg)
+{
+#if LWIP_TCP
+  if (!ERR_IS_FATAL(msg->conn->err)) {
+    if (msg->conn->pcb.tcp != NULL) {
+      if (msg->conn->type == NETCONN_TCP) {
+        if (msg->conn->pcb.tcp->state == CLOSED) {
+#if TCP_LISTEN_BACKLOG
+          struct tcp_pcb* lpcb = tcp_listen_with_backlog(msg->conn->pcb.tcp, msg->msg.lb.backlog);
+#else  /* TCP_LISTEN_BACKLOG */
+          struct tcp_pcb* lpcb = tcp_listen(msg->conn->pcb.tcp);
+#endif /* TCP_LISTEN_BACKLOG */
+          if (lpcb == NULL) {
+            msg->conn->err = ERR_MEM;
+          } else {
+            /* delete the recvmbox and allocate the acceptmbox */
+            if (msg->conn->recvmbox != SYS_MBOX_NULL) {
+              /** @todo: should we drain the recvmbox here? */
+              sys_mbox_free(msg->conn->recvmbox);
+              msg->conn->recvmbox = SYS_MBOX_NULL;
+            }
+            if (msg->conn->acceptmbox == SYS_MBOX_NULL) {
+              if ((msg->conn->acceptmbox = sys_mbox_new(DEFAULT_ACCEPTMBOX_SIZE)) == SYS_MBOX_NULL) {
+                msg->conn->err = ERR_MEM;
+              }
+            }
+            if (msg->conn->err == ERR_OK) {
+              msg->conn->state = NETCONN_LISTEN;
+              msg->conn->pcb.tcp = lpcb;
+              tcp_arg(msg->conn->pcb.tcp, msg->conn);
+              tcp_accept(msg->conn->pcb.tcp, accept_function);
+            }
+          }
+        } else {
+          msg->conn->err = ERR_CONN;
+        }
+      }
+    }
+  }
+#endif /* LWIP_TCP */
+  TCPIP_APIMSG_ACK(msg);
+}
+
+/**
+ * Send some data on a RAW or UDP pcb contained in a netconn
+ * Called from netconn_send
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_send(struct api_msg_msg *msg)
+{
+  if (!ERR_IS_FATAL(msg->conn->err)) {
+    if (msg->conn->pcb.tcp != NULL) {
+      switch (NETCONNTYPE_GROUP(msg->conn->type)) {
+#if LWIP_RAW
+      case NETCONN_RAW:
+        if (msg->msg.b->addr == NULL) {
+          msg->conn->err = raw_send(msg->conn->pcb.raw, msg->msg.b->p);
+        } else {
+          msg->conn->err = raw_sendto(msg->conn->pcb.raw, msg->msg.b->p, msg->msg.b->addr);
+        }
+        break;
+#endif
+#if LWIP_UDP
+      case NETCONN_UDP:
+        if (msg->msg.b->addr == NULL) {
+          msg->conn->err = udp_send(msg->conn->pcb.udp, msg->msg.b->p);
+        } else {
+          msg->conn->err = udp_sendto(msg->conn->pcb.udp, msg->msg.b->p, msg->msg.b->addr, msg->msg.b->port);
+        }
+        break;
+#endif /* LWIP_UDP */
+      default:
+        break;
+      }
+    }
+  }
+  TCPIP_APIMSG_ACK(msg);
+}
+
+/**
+ * Indicate data has been received from a TCP pcb contained in a netconn
+ * Called from netconn_recv
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_recv(struct api_msg_msg *msg)
+{
+#if LWIP_TCP
+  if (!ERR_IS_FATAL(msg->conn->err)) {
+    if (msg->conn->pcb.tcp != NULL) {
+      if (msg->conn->type == NETCONN_TCP) {
+#if TCP_LISTEN_BACKLOG
+        if (msg->conn->pcb.tcp->state == LISTEN) {
+          tcp_accepted(msg->conn->pcb.tcp);
+        } else
+#endif /* TCP_LISTEN_BACKLOG */
+        {
+          tcp_recved(msg->conn->pcb.tcp, msg->msg.r.len);
+        }
+      }
+    }
+  }
+#endif /* LWIP_TCP */
+  TCPIP_APIMSG_ACK(msg);
+}
+
+#if LWIP_TCP
+/**
+ * See if more data needs to be written from a previous call to netconn_write.
+ * Called initially from do_write. If the first call can't send all data
+ * (because of low memory or empty send-buffer), this function is called again
+ * from sent_tcp() or poll_tcp() to send more data. If all data is sent, the
+ * blocking application thread (waiting in netconn_write) is released.
+ *
+ * @param conn netconn (that is currently in state NETCONN_WRITE) to process
+ * @return ERR_OK
+ *         ERR_MEM if LWIP_TCPIP_CORE_LOCKING=1 and sending hasn't yet finished
+ */
+static err_t
+do_writemore(struct netconn *conn)
+{
+  err_t err;
+  void *dataptr;
+  u16_t len, available;
+  u8_t write_finished = 0;
+  size_t diff;
+
+  LWIP_ASSERT("conn->state == NETCONN_WRITE", (conn->state == NETCONN_WRITE));
+
+  dataptr = (u8_t*)conn->write_msg->msg.w.dataptr + conn->write_offset;
+  diff = conn->write_msg->msg.w.len - conn->write_offset;
+  if (diff > 0xffffUL) { /* max_u16_t */
+    len = 0xffff;
+#if LWIP_TCPIP_CORE_LOCKING
+    conn->write_delayed = 1;
+#endif
+  } else {
+    len = (u16_t)diff;
+  }
+  available = tcp_sndbuf(conn->pcb.tcp);
+  if (available < len) {
+    /* don't try to write more than sendbuf */
+    len = available;
+#if LWIP_TCPIP_CORE_LOCKING
+    conn->write_delayed = 1;
+#endif
+  }
+
+  err = tcp_write(conn->pcb.tcp, dataptr, len, conn->write_msg->msg.w.apiflags);
+  LWIP_ASSERT("do_writemore: invalid length!", ((conn->write_offset + len) <= conn->write_msg->msg.w.len));
+  if (err == ERR_OK) {
+    conn->write_offset += len;
+    if (conn->write_offset == conn->write_msg->msg.w.len) {
+      /* everything was written */
+      write_finished = 1;
+      conn->write_msg = NULL;
+      conn->write_offset = 0;
+      /* API_EVENT might call tcp_tmr, so reset conn->state now */
+      conn->state = NETCONN_NONE;
+    }
+    err = tcp_output_nagle(conn->pcb.tcp);
+    conn->err = err;
+    if ((err == ERR_OK) && (tcp_sndbuf(conn->pcb.tcp) <= TCP_SNDLOWAT)) {
+      API_EVENT(conn, NETCONN_EVT_SENDMINUS, len);
+    }
+  } else if (err == ERR_MEM) {
+    /* If ERR_MEM, we wait for sent_tcp or poll_tcp to be called
+       we do NOT return to the application thread, since ERR_MEM is
+       only a temporary error! */
+
+    /* tcp_enqueue returned ERR_MEM, try tcp_output anyway */
+    err = tcp_output(conn->pcb.tcp);
+
+#if LWIP_TCPIP_CORE_LOCKING
+    conn->write_delayed = 1;
+#endif
+  } else {
+    /* On errors != ERR_MEM, we don't try writing any more but return
+       the error to the application thread. */
+    conn->err = err;
+    write_finished = 1;
+  }
+
+  if (write_finished) {
+    /* everything was written: set back connection state
+       and back to application task */
+    conn->state = NETCONN_NONE;
+#if LWIP_TCPIP_CORE_LOCKING
+    if (conn->write_delayed != 0)
+#endif
+    {
+      sys_sem_signal(conn->op_completed);
+    }
+  }
+#if LWIP_TCPIP_CORE_LOCKING
+  else
+    return ERR_MEM;
+#endif
+  return ERR_OK;
+}
+#endif /* LWIP_TCP */
+
+/**
+ * Send some data on a TCP pcb contained in a netconn
+ * Called from netconn_write
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_write(struct api_msg_msg *msg)
+{
+  if (!ERR_IS_FATAL(msg->conn->err)) {
+    if ((msg->conn->pcb.tcp != NULL) && (msg->conn->type == NETCONN_TCP)) {
+#if LWIP_TCP
+      msg->conn->state = NETCONN_WRITE;
+      /* set all the variables used by do_writemore */
+      LWIP_ASSERT("already writing", msg->conn->write_msg == NULL &&
+        msg->conn->write_offset == 0);
+      msg->conn->write_msg = msg;
+      msg->conn->write_offset = 0;
+#if LWIP_TCPIP_CORE_LOCKING
+      msg->conn->write_delayed = 0;
+      if (do_writemore(msg->conn) != ERR_OK) {
+        LWIP_ASSERT("state!", msg->conn->state == NETCONN_WRITE);
+        UNLOCK_TCPIP_CORE();
+        sys_arch_sem_wait(msg->conn->op_completed, 0);
+        LOCK_TCPIP_CORE();
+        LWIP_ASSERT("state!", msg->conn->state == NETCONN_NONE);
+      }
+#else
+      do_writemore(msg->conn);
+#endif
+      /* for both cases: if do_writemore was called, don't ACK the APIMSG! */
+      return;
+#endif /* LWIP_TCP */
+#if (LWIP_UDP || LWIP_RAW)
+    } else {
+      msg->conn->err = ERR_VAL;
+#endif /* (LWIP_UDP || LWIP_RAW) */
+    }
+  }
+  TCPIP_APIMSG_ACK(msg);
+}
+
+/**
+ * Return a connection's local or remote address
+ * Called from netconn_getaddr
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_getaddr(struct api_msg_msg *msg)
+{
+  if (msg->conn->pcb.ip != NULL) {
+    *(msg->msg.ad.ipaddr) = (msg->msg.ad.local?msg->conn->pcb.ip->local_ip:msg->conn->pcb.ip->remote_ip);
+    
+    switch (NETCONNTYPE_GROUP(msg->conn->type)) {
+#if LWIP_RAW
+    case NETCONN_RAW:
+      if (msg->msg.ad.local) {
+        *(msg->msg.ad.port) = msg->conn->pcb.raw->protocol;
+      } else {
+        /* return an error as connecting is only a helper for upper layers */
+        msg->conn->err = ERR_CONN;
+      }
+      break;
+#endif /* LWIP_RAW */
+#if LWIP_UDP
+    case NETCONN_UDP:
+      if (msg->msg.ad.local) {
+        *(msg->msg.ad.port) = msg->conn->pcb.udp->local_port;
+      } else {
+        if ((msg->conn->pcb.udp->flags & UDP_FLAGS_CONNECTED) == 0) {
+          msg->conn->err = ERR_CONN;
+        } else {
+          *(msg->msg.ad.port) = msg->conn->pcb.udp->remote_port;
+        }
+      }
+      break;
+#endif /* LWIP_UDP */
+#if LWIP_TCP
+    case NETCONN_TCP:
+      *(msg->msg.ad.port) = (msg->msg.ad.local?msg->conn->pcb.tcp->local_port:msg->conn->pcb.tcp->remote_port);
+      break;
+#endif /* LWIP_TCP */
+    }
+  } else {
+    msg->conn->err = ERR_CONN;
+  }
+  TCPIP_APIMSG_ACK(msg);
+}
+
+/**
+ * Close a TCP pcb contained in a netconn
+ * Called from netconn_close
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_close(struct api_msg_msg *msg)
+{
+#if LWIP_TCP
+  if ((msg->conn->pcb.tcp != NULL) && (msg->conn->type == NETCONN_TCP)) {
+      msg->conn->state = NETCONN_CLOSE;
+      do_close_internal(msg->conn);
+      /* for tcp netconns, do_close_internal ACKs the message */
+  } else
+#endif /* LWIP_TCP */
+  {
+    msg->conn->err = ERR_VAL;
+    sys_sem_signal(msg->conn->op_completed);
+  }
+}
+
+#if LWIP_IGMP
+/**
+ * Join multicast groups for UDP netconns.
+ * Called from netconn_join_leave_group
+ *
+ * @param msg the api_msg_msg pointing to the connection
+ */
+void
+do_join_leave_group(struct api_msg_msg *msg)
+{ 
+  if (!ERR_IS_FATAL(msg->conn->err)) {
+    if (msg->conn->pcb.tcp != NULL) {
+      if (NETCONNTYPE_GROUP(msg->conn->type) == NETCONN_UDP) {
+#if LWIP_UDP
+        if (msg->msg.jl.join_or_leave == NETCONN_JOIN) {
+          msg->conn->err = igmp_joingroup(msg->msg.jl.interface, msg->msg.jl.multiaddr);
+        } else {
+          msg->conn->err = igmp_leavegroup(msg->msg.jl.interface, msg->msg.jl.multiaddr);
+        }
+#endif /* LWIP_UDP */
+#if (LWIP_TCP || LWIP_RAW)
+      } else {
+        msg->conn->err = ERR_VAL;
+#endif /* (LWIP_TCP || LWIP_RAW) */
+      }
+    }
+  }
+  TCPIP_APIMSG_ACK(msg);
+}
+#endif /* LWIP_IGMP */
+
+#if LWIP_DNS
+/**
+ * Callback function that is called when DNS name is resolved
+ * (or on timeout). A waiting application thread is waked up by
+ * signaling the semaphore.
+ */
+static void
+do_dns_found(const char *name, struct ip_addr *ipaddr, void *arg)
+{
+  struct dns_api_msg *msg = (struct dns_api_msg*)arg;
+
+  LWIP_ASSERT("DNS response for wrong host name", strcmp(msg->name, name) == 0);
+
+  if (ipaddr == NULL) {
+    /* timeout or memory error */
+    *msg->err = ERR_VAL;
+  } else {
+    /* address was resolved */
+    *msg->err = ERR_OK;
+    *msg->addr = *ipaddr;
+  }
+  /* wake up the application task waiting in netconn_gethostbyname */
+  sys_sem_signal(msg->sem);
+}
+
+/**
+ * Execute a DNS query
+ * Called from netconn_gethostbyname
+ *
+ * @param arg the dns_api_msg pointing to the query
+ */
+void
+do_gethostbyname(void *arg)
+{
+  struct dns_api_msg *msg = (struct dns_api_msg*)arg;
+
+  *msg->err = dns_gethostbyname(msg->name, msg->addr, do_dns_found, msg);
+  if (*msg->err != ERR_INPROGRESS) {
+    /* on error or immediate success, wake up the application
+     * task waiting in netconn_gethostbyname */
+    sys_sem_signal(msg->sem);
+  }
+}
+#endif /* LWIP_DNS */
+
+#endif /* LWIP_NETCONN */
diff --git a/components/net/lwip/src/arch/include/arch/cc.h b/components/net/lwip/src/arch/include/arch/cc.h
index 1f18a8dd50..04cddcf141 100644
--- a/components/net/lwip/src/arch/include/arch/cc.h
+++ b/components/net/lwip/src/arch/include/arch/cc.h
@@ -89,9 +89,13 @@ typedef rt_uint32_t	mem_ptr_t;
 #endif
 
 void sys_arch_assert(const char* file, int line);
-#define LWIP_PLATFORM_DIAG(x)	do {rt_kprintf x;} while(0)
+#ifdef LWIP_DEBUG
+#define LWIP_PLATFORM_DIAG(x)	do {rt_kprintf x;} while(0)
 #define LWIP_PLATFORM_ASSERT(x) { rt_kprintf(x); sys_arch_assert(__FILE__, __LINE__); }
-
+#else
+#define LWIP_PLATFORM_DIAG(x)
+#define LWIP_PLATFORM_ASSERT(x)
+#endif
 
 #include "string.h"
 
diff --git a/components/net/lwip/src/lwipopts.h b/components/net/lwip/src/lwipopts.h
index 1e8ebf37f3..08d9f4e551 100644
--- a/components/net/lwip/src/lwipopts.h
+++ b/components/net/lwip/src/lwipopts.h
@@ -116,9 +116,11 @@
 #endif
 
 /* the number of simultaneously queued TCP */
-#ifdef RT_LWIP_TCP_SEG_NUM
-#define MEMP_NUM_TCP_SEG            RT_LWIP_TCP_SEG_NUM
-#endif
+#ifdef RT_LWIP_TCP_SEG_NUM
+#define MEMP_NUM_TCP_SEG            RT_LWIP_TCP_SEG_NUM
+#else
+#define MEMP_NUM_TCP_SEG            TCP_SND_QUEUELEN
+#endif
 
 /* MEMP_NUM_SYS_TIMEOUT: the number of simulateously active
    timeouts. */
diff --git a/components/net/lwip/src/netif/ethernetif.c b/components/net/lwip/src/netif/ethernetif.c
index 76660b04e7..e2730b377c 100644
--- a/components/net/lwip/src/netif/ethernetif.c
+++ b/components/net/lwip/src/netif/ethernetif.c
@@ -367,4 +367,45 @@ void list_if()
 #endif
 }
 FINSH_FUNCTION_EXPORT(list_if, list network interface information);
+
+#include <lwip/tcp.h>
+void list_tcps()
+{
+  struct tcp_pcb *pcb;
+  extern struct tcp_pcb *tcp_active_pcbs;  
+  extern union tcp_listen_pcbs_t tcp_listen_pcbs;
+  extern struct tcp_pcb *tcp_tw_pcbs;
+  extern const char *tcp_state_str[];
+
+  rt_enter_critical();
+  rt_kprintf("Active PCB states:\n");
+  for(pcb = tcp_active_pcbs; pcb != NULL; pcb = pcb->next)
+  {
+    rt_kprintf("%s:%d <==> %s:%d snd_nxt %d rcv_nxt %d ",
+                       inet_ntoa(*((struct in_addr*)&(pcb->local_ip))), pcb->local_port, 
+                       inet_ntoa(*((struct in_addr*)&(pcb->remote_ip))), pcb->remote_port,
+                       pcb->snd_nxt, pcb->rcv_nxt);
+    rt_kprintf("state: %s\n", tcp_state_str[pcb->state]);
+  }
+
+  rt_kprintf("Listen PCB states:\n");
+  for(pcb = (struct tcp_pcb *)tcp_listen_pcbs.pcbs; pcb != NULL; pcb = pcb->next)
+  {
+    rt_kprintf("local port %d ", pcb->local_port);
+    rt_kprintf("state: %s\n", tcp_state_str[pcb->state]);
+  }
+  
+  rt_kprintf("TIME-WAIT PCB states:\n");
+  for(pcb = tcp_tw_pcbs; pcb != NULL; pcb = pcb->next)
+  {
+    rt_kprintf("%s:%d <==> %s:%d snd_nxt %d rcv_nxt %d ",
+                       inet_ntoa(*((struct in_addr*)&(pcb->local_ip))), pcb->local_port, 
+                       inet_ntoa(*((struct in_addr*)&(pcb->remote_ip))), pcb->remote_port,
+                       pcb->snd_nxt, pcb->rcv_nxt);
+    rt_kprintf("state: %s\n", tcp_state_str[pcb->state]);
+  }
+  rt_exit_critical();
+}
+FINSH_FUNCTION_EXPORT(list_tcps, list all of tcp pcb);
+
 #endif