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Posted to commits@mynewt.apache.org by ma...@apache.org on 2016/09/30 00:31:16 UTC

[33/51] [abbrv] [partial] incubator-mynewt-core git commit: net/ip/lwip_base; LwIP.

http://git-wip-us.apache.org/repos/asf/incubator-mynewt-core/blob/f5a0f2a0/net/ip/lwip_base/src/api/sockets.c
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diff --git a/net/ip/lwip_base/src/api/sockets.c b/net/ip/lwip_base/src/api/sockets.c
new file mode 100644
index 0000000..72e777d
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+++ b/net/ip/lwip_base/src/api/sockets.c
@@ -0,0 +1,2801 @@
+/**
+ * @file
+ * Sockets BSD-Like API module
+ *
+ * @defgroup socket Socket API
+ * @ingroup threadsafe_api
+ * BSD-style socket API.\n
+ * Thread-safe, to be called from non-TCPIP threads only.\n
+ * Can be activated by defining @ref LWIP_SOCKET to 1.\n
+ * Header is in posix/sys/socket.h\b
+ */
+
+/*
+ * 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 <ad...@sics.se>
+ *
+ * Improved by Marc Boucher <ma...@mbsi.ca> and David Haas <dh...@alum.rpi.edu>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#if LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */
+
+#include "lwip/sockets.h"
+#include "lwip/api.h"
+#include "lwip/sys.h"
+#include "lwip/igmp.h"
+#include "lwip/inet.h"
+#include "lwip/tcp.h"
+#include "lwip/raw.h"
+#include "lwip/udp.h"
+#include "lwip/memp.h"
+#include "lwip/pbuf.h"
+#include "lwip/priv/tcpip_priv.h"
+#if LWIP_CHECKSUM_ON_COPY
+#include "lwip/inet_chksum.h"
+#endif
+
+#include <string.h>
+
+/* If the netconn API is not required publicly, then we include the necessary
+   files here to get the implementation */
+#if !LWIP_NETCONN
+#undef LWIP_NETCONN
+#define LWIP_NETCONN 1
+#include "api_msg.c"
+#include "api_lib.c"
+#include "netbuf.c"
+#undef LWIP_NETCONN
+#define LWIP_NETCONN 0
+#endif
+
+#if LWIP_IPV4
+#define IP4ADDR_PORT_TO_SOCKADDR(sin, ipaddr, port) do { \
+      (sin)->sin_len = sizeof(struct sockaddr_in); \
+      (sin)->sin_family = AF_INET; \
+      (sin)->sin_port = htons((port)); \
+      inet_addr_from_ipaddr(&(sin)->sin_addr, ipaddr); \
+      memset((sin)->sin_zero, 0, SIN_ZERO_LEN); }while(0)
+#define SOCKADDR4_TO_IP4ADDR_PORT(sin, ipaddr, port) do { \
+    inet_addr_to_ipaddr(ip_2_ip4(ipaddr), &((sin)->sin_addr)); \
+    (port) = ntohs((sin)->sin_port); }while(0)
+#endif /* LWIP_IPV4 */
+
+#if LWIP_IPV6
+#define IP6ADDR_PORT_TO_SOCKADDR(sin6, ipaddr, port) do { \
+      (sin6)->sin6_len = sizeof(struct sockaddr_in6); \
+      (sin6)->sin6_family = AF_INET6; \
+      (sin6)->sin6_port = htons((port)); \
+      (sin6)->sin6_flowinfo = 0; \
+      inet6_addr_from_ip6addr(&(sin6)->sin6_addr, ipaddr); \
+      (sin6)->sin6_scope_id = 0; }while(0)
+#define SOCKADDR6_TO_IP6ADDR_PORT(sin6, ipaddr, port) do { \
+    inet6_addr_to_ip6addr(ip_2_ip6(ipaddr), &((sin6)->sin6_addr)); \
+    (port) = ntohs((sin6)->sin6_port); }while(0)
+#endif /* LWIP_IPV6 */
+
+#if LWIP_IPV4 && LWIP_IPV6
+static void sockaddr_to_ipaddr_port(const struct sockaddr* sockaddr, ip_addr_t* ipaddr, u16_t* port);
+
+#define IS_SOCK_ADDR_LEN_VALID(namelen)  (((namelen) == sizeof(struct sockaddr_in)) || \
+                                         ((namelen) == sizeof(struct sockaddr_in6)))
+#define IS_SOCK_ADDR_TYPE_VALID(name)    (((name)->sa_family == AF_INET) || \
+                                         ((name)->sa_family == AF_INET6))
+#define SOCK_ADDR_TYPE_MATCH(name, sock) \
+       ((((name)->sa_family == AF_INET) && !(NETCONNTYPE_ISIPV6((sock)->conn->type))) || \
+       (((name)->sa_family == AF_INET6) && (NETCONNTYPE_ISIPV6((sock)->conn->type))))
+#define IPADDR_PORT_TO_SOCKADDR(sockaddr, ipaddr, port) do { \
+    if (IP_IS_V6(ipaddr)) { \
+      IP6ADDR_PORT_TO_SOCKADDR((struct sockaddr_in6*)(void*)(sockaddr), ip_2_ip6(ipaddr), port); \
+    } else { \
+      IP4ADDR_PORT_TO_SOCKADDR((struct sockaddr_in*)(void*)(sockaddr), ip_2_ip4(ipaddr), port); \
+    } } while(0)
+#define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) sockaddr_to_ipaddr_port(sockaddr, ipaddr, &(port))
+#define DOMAIN_TO_NETCONN_TYPE(domain, type) (((domain) == AF_INET) ? \
+  (type) : (enum netconn_type)((type) | NETCONN_TYPE_IPV6))
+#elif LWIP_IPV6 /* LWIP_IPV4 && LWIP_IPV6 */
+#define IS_SOCK_ADDR_LEN_VALID(namelen)  ((namelen) == sizeof(struct sockaddr_in6))
+#define IS_SOCK_ADDR_TYPE_VALID(name)    ((name)->sa_family == AF_INET6)
+#define SOCK_ADDR_TYPE_MATCH(name, sock) 1
+#define IPADDR_PORT_TO_SOCKADDR(sockaddr, ipaddr, port) \
+        IP6ADDR_PORT_TO_SOCKADDR((struct sockaddr_in6*)(void*)(sockaddr), ip_2_ip6(ipaddr), port)
+#define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) \
+        SOCKADDR6_TO_IP6ADDR_PORT((const struct sockaddr_in6*)(const void*)(sockaddr), ipaddr, port)
+#define DOMAIN_TO_NETCONN_TYPE(domain, netconn_type) (netconn_type)
+#else /*-> LWIP_IPV4: LWIP_IPV4 && LWIP_IPV6 */
+#define IS_SOCK_ADDR_LEN_VALID(namelen)  ((namelen) == sizeof(struct sockaddr_in))
+#define IS_SOCK_ADDR_TYPE_VALID(name)    ((name)->sa_family == AF_INET)
+#define SOCK_ADDR_TYPE_MATCH(name, sock) 1
+#define IPADDR_PORT_TO_SOCKADDR(sockaddr, ipaddr, port) \
+        IP4ADDR_PORT_TO_SOCKADDR((struct sockaddr_in*)(void*)(sockaddr), ip_2_ip4(ipaddr), port)
+#define SOCKADDR_TO_IPADDR_PORT(sockaddr, ipaddr, port) \
+        SOCKADDR4_TO_IP4ADDR_PORT((const struct sockaddr_in*)(const void*)(sockaddr), ipaddr, port)
+#define DOMAIN_TO_NETCONN_TYPE(domain, netconn_type) (netconn_type)
+#endif /* LWIP_IPV6 */
+
+#define IS_SOCK_ADDR_TYPE_VALID_OR_UNSPEC(name)    (((name)->sa_family == AF_UNSPEC) || \
+                                                    IS_SOCK_ADDR_TYPE_VALID(name))
+#define SOCK_ADDR_TYPE_MATCH_OR_UNSPEC(name, sock) (((name)->sa_family == AF_UNSPEC) || \
+                                                    SOCK_ADDR_TYPE_MATCH(name, sock))
+#define IS_SOCK_ADDR_ALIGNED(name)      ((((mem_ptr_t)(name)) % 4) == 0)
+
+
+#define LWIP_SOCKOPT_CHECK_OPTLEN(optlen, opttype) do { if ((optlen) < sizeof(opttype)) { return EINVAL; }}while(0)
+#define LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, opttype) do { \
+  LWIP_SOCKOPT_CHECK_OPTLEN(optlen, opttype); \
+  if ((sock)->conn == NULL) { return EINVAL; } }while(0)
+#define LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, opttype) do { \
+  LWIP_SOCKOPT_CHECK_OPTLEN(optlen, opttype); \
+  if (((sock)->conn == NULL) || ((sock)->conn->pcb.tcp == NULL)) { return EINVAL; } }while(0)
+#define LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, opttype, netconntype) do { \
+  LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, opttype); \
+  if (NETCONNTYPE_GROUP(netconn_type((sock)->conn)) != netconntype) { return ENOPROTOOPT; } }while(0)
+
+
+#define LWIP_SETGETSOCKOPT_DATA_VAR_REF(name)     API_VAR_REF(name)
+#define LWIP_SETGETSOCKOPT_DATA_VAR_DECLARE(name) API_VAR_DECLARE(struct lwip_setgetsockopt_data, name)
+#define LWIP_SETGETSOCKOPT_DATA_VAR_FREE(name)    API_VAR_FREE(MEMP_SOCKET_SETGETSOCKOPT_DATA, name)
+#if LWIP_MPU_COMPATIBLE
+#define LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(name, sock) do { \
+  name = (struct lwip_setgetsockopt_data *)memp_malloc(MEMP_SOCKET_SETGETSOCKOPT_DATA); \
+  if (name == NULL) { \
+    sock_set_errno(sock, ENOMEM); \
+    return -1; \
+  } }while(0)
+#else /* LWIP_MPU_COMPATIBLE */
+#define LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(name, sock)
+#endif /* LWIP_MPU_COMPATIBLE */
+
+#if LWIP_SO_SNDRCVTIMEO_NONSTANDARD
+#define LWIP_SO_SNDRCVTIMEO_OPTTYPE int
+#define LWIP_SO_SNDRCVTIMEO_SET(optval, val) (*(int *)(optval) = (val))
+#define LWIP_SO_SNDRCVTIMEO_GET_MS(optval)   ((s32_t)*(const int*)(optval))
+#else
+#define LWIP_SO_SNDRCVTIMEO_OPTTYPE struct timeval
+#define LWIP_SO_SNDRCVTIMEO_SET(optval, val)  do { \
+  s32_t loc = (val); \
+  ((struct timeval *)(optval))->tv_sec = (loc) / 1000U; \
+  ((struct timeval *)(optval))->tv_usec = ((loc) % 1000U) * 1000U; }while(0)
+#define LWIP_SO_SNDRCVTIMEO_GET_MS(optval) ((((const struct timeval *)(optval))->tv_sec * 1000U) + (((const struct timeval *)(optval))->tv_usec / 1000U))
+#endif
+
+#define NUM_SOCKETS MEMP_NUM_NETCONN
+
+/** This is overridable for the rare case where more than 255 threads
+ * select on the same socket...
+ */
+#ifndef SELWAIT_T
+#define SELWAIT_T u8_t
+#endif
+
+/** Contains all internal pointers and states used for a socket */
+struct lwip_sock {
+  /** sockets currently are built on netconns, each socket has one netconn */
+  struct netconn *conn;
+  /** data that was left from the previous read */
+  void *lastdata;
+  /** offset in the data that was left from the previous read */
+  u16_t lastoffset;
+  /** number of times data was received, set by event_callback(),
+      tested by the receive and select functions */
+  s16_t rcvevent;
+  /** number of times data was ACKed (free send buffer), set by event_callback(),
+      tested by select */
+  u16_t sendevent;
+  /** error happened for this socket, set by event_callback(), tested by select */
+  u16_t errevent;
+  /** last error that occurred on this socket (in fact, all our errnos fit into an u8_t) */
+  u8_t err;
+  /** counter of how many threads are waiting for this socket using select */
+  SELWAIT_T select_waiting;
+};
+
+#if LWIP_NETCONN_SEM_PER_THREAD
+#define SELECT_SEM_T        sys_sem_t*
+#define SELECT_SEM_PTR(sem) (sem)
+#else /* LWIP_NETCONN_SEM_PER_THREAD */
+#define SELECT_SEM_T        sys_sem_t
+#define SELECT_SEM_PTR(sem) (&(sem))
+#endif /* LWIP_NETCONN_SEM_PER_THREAD */
+
+/** Description for a task waiting in select */
+struct lwip_select_cb {
+  /** Pointer to the next waiting task */
+  struct lwip_select_cb *next;
+  /** Pointer to the previous waiting task */
+  struct lwip_select_cb *prev;
+  /** readset passed to select */
+  fd_set *readset;
+  /** writeset passed to select */
+  fd_set *writeset;
+  /** unimplemented: exceptset passed to select */
+  fd_set *exceptset;
+  /** don't signal the same semaphore twice: set to 1 when signalled */
+  int sem_signalled;
+  /** semaphore to wake up a task waiting for select */
+  SELECT_SEM_T sem;
+};
+
+/** A struct sockaddr replacement that has the same alignment as sockaddr_in/
+ *  sockaddr_in6 if instantiated.
+ */
+union sockaddr_aligned {
+   struct sockaddr sa;
+#if LWIP_IPV6
+   struct sockaddr_in6 sin6;
+#endif /* LWIP_IPV6 */
+#if LWIP_IPV4
+   struct sockaddr_in sin;
+#endif /* LWIP_IPV4 */
+};
+
+#if LWIP_IGMP
+/* Define the number of IPv4 multicast memberships, default is one per socket */
+#ifndef LWIP_SOCKET_MAX_MEMBERSHIPS
+#define LWIP_SOCKET_MAX_MEMBERSHIPS NUM_SOCKETS
+#endif
+
+/* This is to keep track of IP_ADD_MEMBERSHIP calls to drop the membership when
+   a socket is closed */
+struct lwip_socket_multicast_pair {
+  /** the socket (+1 to not require initialization) */
+  int sa;
+  /** the interface address */
+  ip4_addr_t if_addr;
+  /** the group address */
+  ip4_addr_t multi_addr;
+};
+
+struct lwip_socket_multicast_pair socket_ipv4_multicast_memberships[LWIP_SOCKET_MAX_MEMBERSHIPS];
+
+static int  lwip_socket_register_membership(int s, const ip4_addr_t *if_addr, const ip4_addr_t *multi_addr);
+static void lwip_socket_unregister_membership(int s, const ip4_addr_t *if_addr, const ip4_addr_t *multi_addr);
+static void lwip_socket_drop_registered_memberships(int s);
+#endif /* LWIP_IGMP */
+
+/** The global array of available sockets */
+static struct lwip_sock sockets[NUM_SOCKETS];
+/** The global list of tasks waiting for select */
+static struct lwip_select_cb *select_cb_list;
+/** This counter is increased from lwip_select when the list is changed
+    and checked in event_callback to see if it has changed. */
+static volatile int select_cb_ctr;
+
+/** Table to quickly map an lwIP error (err_t) to a socket error
+  * by using -err as an index */
+static const int err_to_errno_table[] = {
+  0,             /* ERR_OK          0      No error, everything OK. */
+  ENOMEM,        /* ERR_MEM        -1      Out of memory error.     */
+  ENOBUFS,       /* ERR_BUF        -2      Buffer error.            */
+  EWOULDBLOCK,   /* ERR_TIMEOUT    -3      Timeout                  */
+  EHOSTUNREACH,  /* ERR_RTE        -4      Routing problem.         */
+  EINPROGRESS,   /* ERR_INPROGRESS -5      Operation in progress    */
+  EINVAL,        /* ERR_VAL        -6      Illegal value.           */
+  EWOULDBLOCK,   /* ERR_WOULDBLOCK -7      Operation would block.   */
+  EADDRINUSE,    /* ERR_USE        -8      Address in use.          */
+  EALREADY,      /* ERR_ALREADY    -9      Already connecting.      */
+  EISCONN,       /* ERR_ISCONN     -10     Conn already established.*/
+  ENOTCONN,      /* ERR_CONN       -11     Not connected.           */
+  -1,            /* ERR_IF         -12     Low-level netif error    */
+  ECONNABORTED,  /* ERR_ABRT       -13     Connection aborted.      */
+  ECONNRESET,    /* ERR_RST        -14     Connection reset.        */
+  ENOTCONN,      /* ERR_CLSD       -15     Connection closed.       */
+  EIO            /* ERR_ARG        -16     Illegal argument.        */
+};
+
+#define ERR_TO_ERRNO_TABLE_SIZE LWIP_ARRAYSIZE(err_to_errno_table)
+
+#define err_to_errno(err) \
+  ((unsigned)(-(signed)(err)) < ERR_TO_ERRNO_TABLE_SIZE ? \
+    err_to_errno_table[-(signed)(err)] : EIO)
+
+#if LWIP_SOCKET_SET_ERRNO
+#ifndef set_errno
+#define set_errno(err) do { if (err) { errno = (err); } } while(0)
+#endif
+#else /* LWIP_SOCKET_SET_ERRNO */
+#define set_errno(err)
+#endif /* LWIP_SOCKET_SET_ERRNO */
+
+#define sock_set_errno(sk, e) do { \
+  const int sockerr = (e); \
+  sk->err = (u8_t)sockerr; \
+  set_errno(sockerr); \
+} while (0)
+
+/* Forward declaration of some functions */
+static void event_callback(struct netconn *conn, enum netconn_evt evt, u16_t len);
+#if !LWIP_TCPIP_CORE_LOCKING
+static void lwip_getsockopt_callback(void *arg);
+static void lwip_setsockopt_callback(void *arg);
+#endif
+static u8_t lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *optlen);
+static u8_t lwip_setsockopt_impl(int s, int level, int optname, const void *optval, socklen_t optlen);
+
+#if LWIP_IPV4 && LWIP_IPV6
+static void
+sockaddr_to_ipaddr_port(const struct sockaddr* sockaddr, ip_addr_t* ipaddr, u16_t* port)
+{
+  if ((sockaddr->sa_family) == AF_INET6) {
+    SOCKADDR6_TO_IP6ADDR_PORT((const struct sockaddr_in6*)(const void*)(sockaddr), ipaddr, *port);
+    ipaddr->type = IPADDR_TYPE_V6;
+  } else {
+    SOCKADDR4_TO_IP4ADDR_PORT((const struct sockaddr_in*)(const void*)(sockaddr), ipaddr, *port);
+    ipaddr->type = IPADDR_TYPE_V4;
+  }
+}
+#endif /* LWIP_IPV4 && LWIP_IPV6 */
+
+/** LWIP_NETCONN_SEM_PER_THREAD==1: initialize thread-local semaphore */
+void
+lwip_socket_thread_init(void)
+{
+   netconn_thread_init();
+}
+
+/** LWIP_NETCONN_SEM_PER_THREAD==1: destroy thread-local semaphore */
+void
+lwip_socket_thread_cleanup(void)
+{
+   netconn_thread_cleanup();
+}
+
+/**
+ * Map a externally used socket index to the internal socket representation.
+ *
+ * @param s externally used socket index
+ * @return struct lwip_sock for the socket or NULL if not found
+ */
+static struct lwip_sock *
+get_socket(int s)
+{
+  struct lwip_sock *sock;
+
+  s -= LWIP_SOCKET_OFFSET;
+
+  if ((s < 0) || (s >= NUM_SOCKETS)) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): invalid\n", s + LWIP_SOCKET_OFFSET));
+    set_errno(EBADF);
+    return NULL;
+  }
+
+  sock = &sockets[s];
+
+  if (!sock->conn) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("get_socket(%d): not active\n", s + LWIP_SOCKET_OFFSET));
+    set_errno(EBADF);
+    return NULL;
+  }
+
+  return sock;
+}
+
+/**
+ * Same as get_socket but doesn't set errno
+ *
+ * @param s externally used socket index
+ * @return struct lwip_sock for the socket or NULL if not found
+ */
+static struct lwip_sock *
+tryget_socket(int s)
+{
+  s -= LWIP_SOCKET_OFFSET;
+  if ((s < 0) || (s >= NUM_SOCKETS)) {
+    return NULL;
+  }
+  if (!sockets[s].conn) {
+    return NULL;
+  }
+  return &sockets[s];
+}
+
+/**
+ * Allocate a new socket for a given netconn.
+ *
+ * @param newconn the netconn for which to allocate a socket
+ * @param accepted 1 if socket has been created by accept(),
+ *                 0 if socket has been created by socket()
+ * @return the index of the new socket; -1 on error
+ */
+static int
+alloc_socket(struct netconn *newconn, int accepted)
+{
+  int i;
+  SYS_ARCH_DECL_PROTECT(lev);
+
+  /* allocate a new socket identifier */
+  for (i = 0; i < NUM_SOCKETS; ++i) {
+    /* Protect socket array */
+    SYS_ARCH_PROTECT(lev);
+    if (!sockets[i].conn) {
+      sockets[i].conn       = newconn;
+      /* The socket is not yet known to anyone, so no need to protect
+         after having marked it as used. */
+      SYS_ARCH_UNPROTECT(lev);
+      sockets[i].lastdata   = NULL;
+      sockets[i].lastoffset = 0;
+      sockets[i].rcvevent   = 0;
+      /* TCP sendbuf is empty, but the socket is not yet writable until connected
+       * (unless it has been created by accept()). */
+      sockets[i].sendevent  = (NETCONNTYPE_GROUP(newconn->type) == NETCONN_TCP ? (accepted != 0) : 1);
+      sockets[i].errevent   = 0;
+      sockets[i].err        = 0;
+      sockets[i].select_waiting = 0;
+      return i + LWIP_SOCKET_OFFSET;
+    }
+    SYS_ARCH_UNPROTECT(lev);
+  }
+  return -1;
+}
+
+/** Free a socket. The socket's netconn must have been
+ * delete before!
+ *
+ * @param sock the socket to free
+ * @param is_tcp != 0 for TCP sockets, used to free lastdata
+ */
+static void
+free_socket(struct lwip_sock *sock, int is_tcp)
+{
+  void *lastdata;
+
+  lastdata         = sock->lastdata;
+  sock->lastdata   = NULL;
+  sock->lastoffset = 0;
+  sock->err        = 0;
+
+  /* Protect socket array */
+  SYS_ARCH_SET(sock->conn, NULL);
+  /* don't use 'sock' after this line, as another task might have allocated it */
+
+  if (lastdata != NULL) {
+    if (is_tcp) {
+      pbuf_free((struct pbuf *)lastdata);
+    } else {
+      netbuf_delete((struct netbuf *)lastdata);
+    }
+  }
+}
+
+/* Below this, the well-known socket functions are implemented.
+ * Use google.com or opengroup.org to get a good description :-)
+ *
+ * Exceptions are documented!
+ */
+
+int
+lwip_accept(int s, struct sockaddr *addr, socklen_t *addrlen)
+{
+  struct lwip_sock *sock, *nsock;
+  struct netconn *newconn;
+  ip_addr_t naddr;
+  u16_t port = 0;
+  int newsock;
+  err_t err;
+  SYS_ARCH_DECL_PROTECT(lev);
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d)...\n", s));
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (netconn_is_nonblocking(sock->conn) && (sock->rcvevent <= 0)) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): returning EWOULDBLOCK\n", s));
+    sock_set_errno(sock, EWOULDBLOCK);
+    return -1;
+  }
+
+  /* wait for a new connection */
+  err = netconn_accept(sock->conn, &newconn);
+  if (err != ERR_OK) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): netconn_acept failed, err=%d\n", s, err));
+    if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
+      sock_set_errno(sock, EOPNOTSUPP);
+    } else if (err == ERR_CLSD) {
+      sock_set_errno(sock, EINVAL);
+    } else {
+      sock_set_errno(sock, err_to_errno(err));
+    }
+    return -1;
+  }
+  LWIP_ASSERT("newconn != NULL", newconn != NULL);
+
+  newsock = alloc_socket(newconn, 1);
+  if (newsock == -1) {
+    netconn_delete(newconn);
+    sock_set_errno(sock, ENFILE);
+    return -1;
+  }
+  LWIP_ASSERT("invalid socket index", (newsock >= LWIP_SOCKET_OFFSET) && (newsock < NUM_SOCKETS + LWIP_SOCKET_OFFSET));
+  LWIP_ASSERT("newconn->callback == event_callback", newconn->callback == event_callback);
+  nsock = &sockets[newsock - LWIP_SOCKET_OFFSET];
+
+  /* See event_callback: If data comes in right away after an accept, even
+   * though the server task might not have created a new socket yet.
+   * In that case, newconn->socket is counted down (newconn->socket--),
+   * so nsock->rcvevent is >= 1 here!
+   */
+  SYS_ARCH_PROTECT(lev);
+  nsock->rcvevent += (s16_t)(-1 - newconn->socket);
+  newconn->socket = newsock;
+  SYS_ARCH_UNPROTECT(lev);
+
+  /* Note that POSIX only requires us to check addr is non-NULL. addrlen must
+   * not be NULL if addr is valid.
+   */
+  if (addr != NULL) {
+    union sockaddr_aligned tempaddr;
+    /* get the IP address and port of the remote host */
+    err = netconn_peer(newconn, &naddr, &port);
+    if (err != ERR_OK) {
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d): netconn_peer failed, err=%d\n", s, err));
+      netconn_delete(newconn);
+      free_socket(nsock, 1);
+      sock_set_errno(sock, err_to_errno(err));
+      return -1;
+    }
+    LWIP_ASSERT("addr valid but addrlen NULL", addrlen != NULL);
+
+    IPADDR_PORT_TO_SOCKADDR(&tempaddr, &naddr, port);
+    if (*addrlen > tempaddr.sa.sa_len) {
+      *addrlen = tempaddr.sa.sa_len;
+    }
+    MEMCPY(addr, &tempaddr, *addrlen);
+
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d) returning new sock=%d addr=", s, newsock));
+    ip_addr_debug_print_val(SOCKETS_DEBUG, naddr);
+    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F"\n", port));
+  } else {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_accept(%d) returning new sock=%d", s, newsock));
+  }
+
+  sock_set_errno(sock, 0);
+  return newsock;
+}
+
+int
+lwip_bind(int s, const struct sockaddr *name, socklen_t namelen)
+{
+  struct lwip_sock *sock;
+  ip_addr_t local_addr;
+  u16_t local_port;
+  err_t err;
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (!SOCK_ADDR_TYPE_MATCH(name, sock)) {
+    /* sockaddr does not match socket type (IPv4/IPv6) */
+    sock_set_errno(sock, err_to_errno(ERR_VAL));
+    return -1;
+  }
+
+  /* check size, family and alignment of 'name' */
+  LWIP_ERROR("lwip_bind: invalid address", (IS_SOCK_ADDR_LEN_VALID(namelen) &&
+             IS_SOCK_ADDR_TYPE_VALID(name) && IS_SOCK_ADDR_ALIGNED(name)),
+             sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
+  LWIP_UNUSED_ARG(namelen);
+
+  SOCKADDR_TO_IPADDR_PORT(name, &local_addr, local_port);
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d, addr=", s));
+  ip_addr_debug_print_val(SOCKETS_DEBUG, local_addr);
+  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", local_port));
+
+  err = netconn_bind(sock->conn, &local_addr, local_port);
+
+  if (err != ERR_OK) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) failed, err=%d\n", s, err));
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_bind(%d) succeeded\n", s));
+  sock_set_errno(sock, 0);
+  return 0;
+}
+
+int
+lwip_close(int s)
+{
+  struct lwip_sock *sock;
+  int is_tcp = 0;
+  err_t err;
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_close(%d)\n", s));
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (sock->conn != NULL) {
+    is_tcp = NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP;
+  } else {
+    LWIP_ASSERT("sock->lastdata == NULL", sock->lastdata == NULL);
+  }
+
+#if LWIP_IGMP
+  /* drop all possibly joined IGMP memberships */
+  lwip_socket_drop_registered_memberships(s);
+#endif /* LWIP_IGMP */
+
+  err = netconn_delete(sock->conn);
+  if (err != ERR_OK) {
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+
+  free_socket(sock, is_tcp);
+  set_errno(0);
+  return 0;
+}
+
+int
+lwip_connect(int s, const struct sockaddr *name, socklen_t namelen)
+{
+  struct lwip_sock *sock;
+  err_t err;
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (!SOCK_ADDR_TYPE_MATCH_OR_UNSPEC(name, sock)) {
+    /* sockaddr does not match socket type (IPv4/IPv6) */
+    sock_set_errno(sock, err_to_errno(ERR_VAL));
+    return -1;
+  }
+
+  LWIP_UNUSED_ARG(namelen);
+  if (name->sa_family == AF_UNSPEC) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, AF_UNSPEC)\n", s));
+    err = netconn_disconnect(sock->conn);
+  } else {
+    ip_addr_t remote_addr;
+    u16_t remote_port;
+
+    /* check size, family and alignment of 'name' */
+    LWIP_ERROR("lwip_connect: invalid address", IS_SOCK_ADDR_LEN_VALID(namelen) &&
+               IS_SOCK_ADDR_TYPE_VALID_OR_UNSPEC(name) && IS_SOCK_ADDR_ALIGNED(name),
+               sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
+
+    SOCKADDR_TO_IPADDR_PORT(name, &remote_addr, remote_port);
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d, addr=", s));
+    ip_addr_debug_print_val(SOCKETS_DEBUG, remote_addr);
+    LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", remote_port));
+
+    err = netconn_connect(sock->conn, &remote_addr, remote_port);
+  }
+
+  if (err != ERR_OK) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) failed, err=%d\n", s, err));
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_connect(%d) succeeded\n", s));
+  sock_set_errno(sock, 0);
+  return 0;
+}
+
+/**
+ * Set a socket into listen mode.
+ * The socket may not have been used for another connection previously.
+ *
+ * @param s the socket to set to listening mode
+ * @param backlog (ATTENTION: needs TCP_LISTEN_BACKLOG=1)
+ * @return 0 on success, non-zero on failure
+ */
+int
+lwip_listen(int s, int backlog)
+{
+  struct lwip_sock *sock;
+  err_t err;
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d, backlog=%d)\n", s, backlog));
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  /* limit the "backlog" parameter to fit in an u8_t */
+  backlog = LWIP_MIN(LWIP_MAX(backlog, 0), 0xff);
+
+  err = netconn_listen_with_backlog(sock->conn, (u8_t)backlog);
+
+  if (err != ERR_OK) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_listen(%d) failed, err=%d\n", s, err));
+    if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
+      sock_set_errno(sock, EOPNOTSUPP);
+      return -1;
+    }
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+
+  sock_set_errno(sock, 0);
+  return 0;
+}
+
+int
+lwip_recvfrom(int s, void *mem, size_t len, int flags,
+              struct sockaddr *from, socklen_t *fromlen)
+{
+  struct lwip_sock *sock;
+  void             *buf = NULL;
+  struct pbuf      *p;
+  u16_t            buflen, copylen;
+  int              off = 0;
+  u8_t             done = 0;
+  err_t            err;
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d, %p, %"SZT_F", 0x%x, ..)\n", s, mem, len, flags));
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  do {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: top while sock->lastdata=%p\n", sock->lastdata));
+    /* Check if there is data left from the last recv operation. */
+    if (sock->lastdata) {
+      buf = sock->lastdata;
+    } else {
+      /* If this is non-blocking call, then check first */
+      if (((flags & MSG_DONTWAIT) || netconn_is_nonblocking(sock->conn)) &&
+          (sock->rcvevent <= 0)) {
+        if (off > 0) {
+          /* already received data, return that */
+          sock_set_errno(sock, 0);
+          return off;
+        }
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): returning EWOULDBLOCK\n", s));
+        sock_set_errno(sock, EWOULDBLOCK);
+        return -1;
+      }
+
+      /* No data was left from the previous operation, so we try to get
+         some from the network. */
+      if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+        err = netconn_recv_tcp_pbuf(sock->conn, (struct pbuf **)&buf);
+      } else {
+        err = netconn_recv(sock->conn, (struct netbuf **)&buf);
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: netconn_recv err=%d, netbuf=%p\n",
+        err, buf));
+
+      if (err != ERR_OK) {
+        if (off > 0) {
+          if (err == ERR_CLSD) {
+            /* closed but already received data, ensure select gets the FIN, too */
+            event_callback(sock->conn, NETCONN_EVT_RCVPLUS, 0);
+          }
+          /* already received data, return that */
+          sock_set_errno(sock, 0);
+          return off;
+        }
+        /* We should really do some error checking here. */
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): buf == NULL, error is \"%s\"!\n",
+          s, lwip_strerr(err)));
+        sock_set_errno(sock, err_to_errno(err));
+        if (err == ERR_CLSD) {
+          return 0;
+        } else {
+          return -1;
+        }
+      }
+      LWIP_ASSERT("buf != NULL", buf != NULL);
+      sock->lastdata = buf;
+    }
+
+    if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+      p = (struct pbuf *)buf;
+    } else {
+      p = ((struct netbuf *)buf)->p;
+    }
+    buflen = p->tot_len;
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: buflen=%"U16_F" len=%"SZT_F" off=%d sock->lastoffset=%"U16_F"\n",
+      buflen, len, off, sock->lastoffset));
+
+    buflen -= sock->lastoffset;
+
+    if (len > buflen) {
+      copylen = buflen;
+    } else {
+      copylen = (u16_t)len;
+    }
+
+    /* copy the contents of the received buffer into
+    the supplied memory pointer mem */
+    pbuf_copy_partial(p, (u8_t*)mem + off, copylen, sock->lastoffset);
+
+    off += copylen;
+
+    if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+      LWIP_ASSERT("invalid copylen, len would underflow", len >= copylen);
+      len -= copylen;
+      if ((len <= 0) ||
+          (p->flags & PBUF_FLAG_PUSH) ||
+          (sock->rcvevent <= 0) ||
+          ((flags & MSG_PEEK) != 0)) {
+        done = 1;
+      }
+    } else {
+      done = 1;
+    }
+
+    /* Check to see from where the data was.*/
+    if (done) {
+#if !SOCKETS_DEBUG
+      if (from && fromlen)
+#endif /* !SOCKETS_DEBUG */
+      {
+        u16_t port;
+        ip_addr_t tmpaddr;
+        ip_addr_t *fromaddr;
+        union sockaddr_aligned saddr;
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom(%d): addr=", s));
+        if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+          fromaddr = &tmpaddr;
+          netconn_getaddr(sock->conn, fromaddr, &port, 0);
+        } else {
+          port = netbuf_fromport((struct netbuf *)buf);
+          fromaddr = netbuf_fromaddr((struct netbuf *)buf);
+        }
+        IPADDR_PORT_TO_SOCKADDR(&saddr, fromaddr, port);
+        ip_addr_debug_print(SOCKETS_DEBUG, fromaddr);
+        LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F" len=%d\n", port, off));
+#if SOCKETS_DEBUG
+        if (from && fromlen)
+#endif /* SOCKETS_DEBUG */
+        {
+          if (*fromlen > saddr.sa.sa_len) {
+            *fromlen = saddr.sa.sa_len;
+          }
+          MEMCPY(from, &saddr, *fromlen);
+        }
+      }
+    }
+
+    /* If we don't peek the incoming message... */
+    if ((flags & MSG_PEEK) == 0) {
+      /* If this is a TCP socket, check if there is data left in the
+         buffer. If so, it should be saved in the sock structure for next
+         time around. */
+      if ((NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) && (buflen - copylen > 0)) {
+        sock->lastdata = buf;
+        sock->lastoffset += copylen;
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: lastdata now netbuf=%p\n", buf));
+      } else {
+        sock->lastdata = NULL;
+        sock->lastoffset = 0;
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_recvfrom: deleting netbuf=%p\n", buf));
+        if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+          pbuf_free((struct pbuf *)buf);
+        } else {
+          netbuf_delete((struct netbuf *)buf);
+        }
+        buf = NULL;
+      }
+    }
+  } while (!done);
+
+  sock_set_errno(sock, 0);
+  return off;
+}
+
+int
+lwip_read(int s, void *mem, size_t len)
+{
+  return lwip_recvfrom(s, mem, len, 0, NULL, NULL);
+}
+
+int
+lwip_recv(int s, void *mem, size_t len, int flags)
+{
+  return lwip_recvfrom(s, mem, len, flags, NULL, NULL);
+}
+
+int
+lwip_send(int s, const void *data, size_t size, int flags)
+{
+  struct lwip_sock *sock;
+  err_t err;
+  u8_t write_flags;
+  size_t written;
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d, data=%p, size=%"SZT_F", flags=0x%x)\n",
+                              s, data, size, flags));
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
+#if (LWIP_UDP || LWIP_RAW)
+    return lwip_sendto(s, data, size, flags, NULL, 0);
+#else /* (LWIP_UDP || LWIP_RAW) */
+    sock_set_errno(sock, err_to_errno(ERR_ARG));
+    return -1;
+#endif /* (LWIP_UDP || LWIP_RAW) */
+  }
+
+  write_flags = NETCONN_COPY |
+    ((flags & MSG_MORE)     ? NETCONN_MORE      : 0) |
+    ((flags & MSG_DONTWAIT) ? NETCONN_DONTBLOCK : 0);
+  written = 0;
+  err = netconn_write_partly(sock->conn, data, size, write_flags, &written);
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_send(%d) err=%d written=%"SZT_F"\n", s, err, written));
+  sock_set_errno(sock, err_to_errno(err));
+  return (err == ERR_OK ? (int)written : -1);
+}
+
+int
+lwip_sendmsg(int s, const struct msghdr *msg, int flags)
+{
+  struct lwip_sock *sock;
+  int i;
+#if LWIP_TCP
+  u8_t write_flags;
+  size_t written;
+#endif
+  int size = 0;
+  err_t err = ERR_OK;
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  LWIP_ERROR("lwip_sendmsg: invalid msghdr", msg != NULL,
+             sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
+
+  LWIP_UNUSED_ARG(msg->msg_control);
+  LWIP_UNUSED_ARG(msg->msg_controllen);
+  LWIP_UNUSED_ARG(msg->msg_flags);
+  LWIP_ERROR("lwip_sendmsg: invalid msghdr iov", (msg->msg_iov != NULL && msg->msg_iovlen != 0),
+             sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
+
+  if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+#if LWIP_TCP
+    write_flags = NETCONN_COPY |
+    ((flags & MSG_MORE)     ? NETCONN_MORE      : 0) |
+    ((flags & MSG_DONTWAIT) ? NETCONN_DONTBLOCK : 0);
+
+    for (i = 0; i < msg->msg_iovlen; i++) {
+      written = 0;
+      err = netconn_write_partly(sock->conn, msg->msg_iov[i].iov_base, msg->msg_iov[i].iov_len, write_flags, &written);
+      if (err == ERR_OK) {
+        size += written;
+        /* check that the entire IO vector was accepected, if not return a partial write */
+        if (written != msg->msg_iov[i].iov_len)
+          break;
+      }
+      /* none of this IO vector was accepted, but previous was, return partial write and conceal ERR_WOULDBLOCK */
+      else if (err == ERR_WOULDBLOCK && size > 0) {
+        err = ERR_OK;
+        /* let ERR_WOULDBLOCK persist on the netconn since we are returning ERR_OK */
+        break;
+      } else {
+        size = -1;
+        break;
+      }
+    }
+    sock_set_errno(sock, err_to_errno(err));
+    return size;
+#else /* LWIP_TCP */
+    sock_set_errno(sock, err_to_errno(ERR_ARG));
+    return -1;
+#endif /* LWIP_TCP */
+  }
+  /* else, UDP and RAW NETCONNs */
+#if LWIP_UDP || LWIP_RAW
+  {
+    struct netbuf *chain_buf;
+
+    LWIP_UNUSED_ARG(flags);
+    LWIP_ERROR("lwip_sendmsg: invalid msghdr name", (((msg->msg_name == NULL) && (msg->msg_namelen == 0)) ||
+               IS_SOCK_ADDR_LEN_VALID(msg->msg_namelen)) ,
+               sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
+
+    /* initialize chain buffer with destination */
+    chain_buf = netbuf_new();
+    if (!chain_buf) {
+      sock_set_errno(sock, err_to_errno(ERR_MEM));
+      return -1;
+    }
+    if (msg->msg_name) {
+      u16_t remote_port;
+      SOCKADDR_TO_IPADDR_PORT((const struct sockaddr *)msg->msg_name, &chain_buf->addr, remote_port);
+      netbuf_fromport(chain_buf) = remote_port;
+    }
+#if LWIP_NETIF_TX_SINGLE_PBUF
+    for (i = 0; i < msg->msg_iovlen; i++) {
+      size += msg->msg_iov[i].iov_len;
+    }
+    /* Allocate a new netbuf and copy the data into it. */
+    if (netbuf_alloc(chain_buf, (u16_t)size) == NULL) {
+       err = ERR_MEM;
+    } else {
+      /* flatten the IO vectors */
+      size_t offset = 0;
+      for (i = 0; i < msg->msg_iovlen; i++) {
+        MEMCPY(&((u8_t*)chain_buf->p->payload)[offset], msg->msg_iov[i].iov_base, msg->msg_iov[i].iov_len);
+        offset += msg->msg_iov[i].iov_len;
+      }
+#if LWIP_CHECKSUM_ON_COPY
+      {
+        /* This can be improved by using LWIP_CHKSUM_COPY() and aggregating the checksum for each IO vector */
+        u16_t chksum = ~inet_chksum_pbuf(chain_buf->p);
+        netbuf_set_chksum(chain_buf, chksum);
+      }
+#endif /* LWIP_CHECKSUM_ON_COPY */
+      err = ERR_OK;
+    }
+#else /* LWIP_NETIF_TX_SINGLE_PBUF */
+    /* create a chained netbuf from the IO vectors. NOTE: we assemble a pbuf chain
+       manually to avoid having to allocate, chain, and delete a netbuf for each iov */
+    for (i = 0; i < msg->msg_iovlen; i++) {
+      struct pbuf *p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_REF);
+      if (p == NULL) {
+        err = ERR_MEM; /* let netbuf_delete() cleanup chain_buf */
+        break;
+      }
+      p->payload = msg->msg_iov[i].iov_base;
+      LWIP_ASSERT("iov_len < u16_t", msg->msg_iov[i].iov_len <= 0xFFFF);
+      p->len = p->tot_len = (u16_t)msg->msg_iov[i].iov_len;
+      /* netbuf empty, add new pbuf */
+      if (chain_buf->p == NULL) {
+        chain_buf->p = chain_buf->ptr = p;
+        /* add pbuf to existing pbuf chain */
+      } else {
+        pbuf_cat(chain_buf->p, p);
+      }
+    }
+    /* save size of total chain */
+    if (err == ERR_OK) {
+      size = netbuf_len(chain_buf);
+    }
+#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
+
+    if (err == ERR_OK) {
+      /* send the data */
+      err = netconn_send(sock->conn, chain_buf);
+    }
+
+    /* deallocated the buffer */
+    netbuf_delete(chain_buf);
+
+    sock_set_errno(sock, err_to_errno(err));
+    return (err == ERR_OK ? size : -1);
+  }
+#else /* LWIP_UDP || LWIP_RAW */
+  sock_set_errno(sock, err_to_errno(ERR_ARG));
+  return -1;
+#endif /* LWIP_UDP || LWIP_RAW */
+}
+
+int
+lwip_sendto(int s, const void *data, size_t size, int flags,
+       const struct sockaddr *to, socklen_t tolen)
+{
+  struct lwip_sock *sock;
+  err_t err;
+  u16_t short_size;
+  u16_t remote_port;
+  struct netbuf buf;
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) {
+#if LWIP_TCP
+    return lwip_send(s, data, size, flags);
+#else /* LWIP_TCP */
+    LWIP_UNUSED_ARG(flags);
+    sock_set_errno(sock, err_to_errno(ERR_ARG));
+    return -1;
+#endif /* LWIP_TCP */
+  }
+
+  if ((to != NULL) && !SOCK_ADDR_TYPE_MATCH(to, sock)) {
+    /* sockaddr does not match socket type (IPv4/IPv6) */
+    sock_set_errno(sock, err_to_errno(ERR_VAL));
+    return -1;
+  }
+
+  /* @todo: split into multiple sendto's? */
+  LWIP_ASSERT("lwip_sendto: size must fit in u16_t", size <= 0xffff);
+  short_size = (u16_t)size;
+  LWIP_ERROR("lwip_sendto: invalid address", (((to == NULL) && (tolen == 0)) ||
+             (IS_SOCK_ADDR_LEN_VALID(tolen) &&
+             IS_SOCK_ADDR_TYPE_VALID(to) && IS_SOCK_ADDR_ALIGNED(to))),
+             sock_set_errno(sock, err_to_errno(ERR_ARG)); return -1;);
+  LWIP_UNUSED_ARG(tolen);
+
+  /* initialize a buffer */
+  buf.p = buf.ptr = NULL;
+#if LWIP_CHECKSUM_ON_COPY
+  buf.flags = 0;
+#endif /* LWIP_CHECKSUM_ON_COPY */
+  if (to) {
+    SOCKADDR_TO_IPADDR_PORT(to, &buf.addr, remote_port);
+  } else {
+    remote_port = 0;
+    ip_addr_set_any(NETCONNTYPE_ISIPV6(netconn_type(sock->conn)), &buf.addr);
+  }
+  netbuf_fromport(&buf) = remote_port;
+
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_sendto(%d, data=%p, short_size=%"U16_F", flags=0x%x to=",
+              s, data, short_size, flags));
+  ip_addr_debug_print(SOCKETS_DEBUG, &buf.addr);
+  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F"\n", remote_port));
+
+  /* make the buffer point to the data that should be sent */
+#if LWIP_NETIF_TX_SINGLE_PBUF
+  /* Allocate a new netbuf and copy the data into it. */
+  if (netbuf_alloc(&buf, short_size) == NULL) {
+    err = ERR_MEM;
+  } else {
+#if LWIP_CHECKSUM_ON_COPY
+    if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_RAW) {
+      u16_t chksum = LWIP_CHKSUM_COPY(buf.p->payload, data, short_size);
+      netbuf_set_chksum(&buf, chksum);
+    } else
+#endif /* LWIP_CHECKSUM_ON_COPY */
+    {
+      MEMCPY(buf.p->payload, data, short_size);
+    }
+    err = ERR_OK;
+  }
+#else /* LWIP_NETIF_TX_SINGLE_PBUF */
+  err = netbuf_ref(&buf, data, short_size);
+#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
+  if (err == ERR_OK) {
+    /* send the data */
+    err = netconn_send(sock->conn, &buf);
+  }
+
+  /* deallocated the buffer */
+  netbuf_free(&buf);
+
+  sock_set_errno(sock, err_to_errno(err));
+  return (err == ERR_OK ? short_size : -1);
+}
+
+int
+lwip_socket(int domain, int type, int protocol)
+{
+  struct netconn *conn;
+  int i;
+
+#if !LWIP_IPV6
+  LWIP_UNUSED_ARG(domain); /* @todo: check this */
+#endif /* LWIP_IPV6 */
+
+  /* create a netconn */
+  switch (type) {
+  case SOCK_RAW:
+    conn = netconn_new_with_proto_and_callback(DOMAIN_TO_NETCONN_TYPE(domain, NETCONN_RAW),
+                                               (u8_t)protocol, event_callback);
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_RAW, %d) = ",
+                                 domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
+    break;
+  case SOCK_DGRAM:
+    conn = netconn_new_with_callback(DOMAIN_TO_NETCONN_TYPE(domain,
+                 ((protocol == IPPROTO_UDPLITE) ? NETCONN_UDPLITE : NETCONN_UDP)) ,
+                 event_callback);
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_DGRAM, %d) = ",
+                                 domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
+    break;
+  case SOCK_STREAM:
+    conn = netconn_new_with_callback(DOMAIN_TO_NETCONN_TYPE(domain, NETCONN_TCP), event_callback);
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%s, SOCK_STREAM, %d) = ",
+                                 domain == PF_INET ? "PF_INET" : "UNKNOWN", protocol));
+    break;
+  default:
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_socket(%d, %d/UNKNOWN, %d) = -1\n",
+                                 domain, type, protocol));
+    set_errno(EINVAL);
+    return -1;
+  }
+
+  if (!conn) {
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("-1 / ENOBUFS (could not create netconn)\n"));
+    set_errno(ENOBUFS);
+    return -1;
+  }
+
+  i = alloc_socket(conn, 0);
+
+  if (i == -1) {
+    netconn_delete(conn);
+    set_errno(ENFILE);
+    return -1;
+  }
+  conn->socket = i;
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("%d\n", i));
+  set_errno(0);
+  return i;
+}
+
+int
+lwip_write(int s, const void *data, size_t size)
+{
+  return lwip_send(s, data, size, 0);
+}
+
+int
+lwip_writev(int s, const struct iovec *iov, int iovcnt)
+{
+  struct msghdr msg;
+
+  msg.msg_name = NULL;
+  msg.msg_namelen = 0;
+  /* Hack: we have to cast via number to cast from 'const' pointer to non-const.
+     Blame the opengroup standard for this inconsistency. */
+  msg.msg_iov = (struct iovec *)(size_t)iov;
+  msg.msg_iovlen = iovcnt;
+  msg.msg_control = NULL;
+  msg.msg_controllen = 0;
+  msg.msg_flags = 0;
+  return lwip_sendmsg(s, &msg, 0);
+}
+
+/**
+ * Go through the readset and writeset lists and see which socket of the sockets
+ * set in the sets has events. On return, readset, writeset and exceptset have
+ * the sockets enabled that had events.
+ *
+ * @param maxfdp1 the highest socket index in the sets
+ * @param readset_in:    set of sockets to check for read events
+ * @param writeset_in:   set of sockets to check for write events
+ * @param exceptset_in:  set of sockets to check for error events
+ * @param readset_out:   set of sockets that had read events
+ * @param writeset_out:  set of sockets that had write events
+ * @param exceptset_out: set os sockets that had error events
+ * @return number of sockets that had events (read/write/exception) (>= 0)
+ */
+static int
+lwip_selscan(int maxfdp1, fd_set *readset_in, fd_set *writeset_in, fd_set *exceptset_in,
+             fd_set *readset_out, fd_set *writeset_out, fd_set *exceptset_out)
+{
+  int i, nready = 0;
+  fd_set lreadset, lwriteset, lexceptset;
+  struct lwip_sock *sock;
+  SYS_ARCH_DECL_PROTECT(lev);
+
+  FD_ZERO(&lreadset);
+  FD_ZERO(&lwriteset);
+  FD_ZERO(&lexceptset);
+
+  /* Go through each socket in each list to count number of sockets which
+     currently match */
+  for (i = LWIP_SOCKET_OFFSET; i < maxfdp1; i++) {
+    /* if this FD is not in the set, continue */
+    if (!(readset_in && FD_ISSET(i, readset_in)) &&
+        !(writeset_in && FD_ISSET(i, writeset_in)) &&
+        !(exceptset_in && FD_ISSET(i, exceptset_in))) {
+      continue;
+    }
+    /* First get the socket's status (protected)... */
+    SYS_ARCH_PROTECT(lev);
+    sock = tryget_socket(i);
+    if (sock != NULL) {
+      void* lastdata = sock->lastdata;
+      s16_t rcvevent = sock->rcvevent;
+      u16_t sendevent = sock->sendevent;
+      u16_t errevent = sock->errevent;
+      SYS_ARCH_UNPROTECT(lev);
+
+      /* ... then examine it: */
+      /* See if netconn of this socket is ready for read */
+      if (readset_in && FD_ISSET(i, readset_in) && ((lastdata != NULL) || (rcvevent > 0))) {
+        FD_SET(i, &lreadset);
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for reading\n", i));
+        nready++;
+      }
+      /* See if netconn of this socket is ready for write */
+      if (writeset_in && FD_ISSET(i, writeset_in) && (sendevent != 0)) {
+        FD_SET(i, &lwriteset);
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for writing\n", i));
+        nready++;
+      }
+      /* See if netconn of this socket had an error */
+      if (exceptset_in && FD_ISSET(i, exceptset_in) && (errevent != 0)) {
+        FD_SET(i, &lexceptset);
+        LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_selscan: fd=%d ready for exception\n", i));
+        nready++;
+      }
+    } else {
+      SYS_ARCH_UNPROTECT(lev);
+      /* continue on to next FD in list */
+    }
+  }
+  /* copy local sets to the ones provided as arguments */
+  *readset_out = lreadset;
+  *writeset_out = lwriteset;
+  *exceptset_out = lexceptset;
+
+  LWIP_ASSERT("nready >= 0", nready >= 0);
+  return nready;
+}
+
+int
+lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
+            struct timeval *timeout)
+{
+  u32_t waitres = 0;
+  int nready;
+  fd_set lreadset, lwriteset, lexceptset;
+  u32_t msectimeout;
+  struct lwip_select_cb select_cb;
+  int i;
+  int maxfdp2;
+#if LWIP_NETCONN_SEM_PER_THREAD
+  int waited = 0;
+#endif
+  SYS_ARCH_DECL_PROTECT(lev);
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select(%d, %p, %p, %p, tvsec=%"S32_F" tvusec=%"S32_F")\n",
+                  maxfdp1, (void *)readset, (void *) writeset, (void *) exceptset,
+                  timeout ? (s32_t)timeout->tv_sec : (s32_t)-1,
+                  timeout ? (s32_t)timeout->tv_usec : (s32_t)-1));
+
+  /* Go through each socket in each list to count number of sockets which
+     currently match */
+  nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
+
+  /* If we don't have any current events, then suspend if we are supposed to */
+  if (!nready) {
+    if (timeout && timeout->tv_sec == 0 && timeout->tv_usec == 0) {
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: no timeout, returning 0\n"));
+      /* This is OK as the local fdsets are empty and nready is zero,
+         or we would have returned earlier. */
+      goto return_copy_fdsets;
+    }
+
+    /* None ready: add our semaphore to list:
+       We don't actually need any dynamic memory. Our entry on the
+       list is only valid while we are in this function, so it's ok
+       to use local variables. */
+
+    select_cb.next = NULL;
+    select_cb.prev = NULL;
+    select_cb.readset = readset;
+    select_cb.writeset = writeset;
+    select_cb.exceptset = exceptset;
+    select_cb.sem_signalled = 0;
+#if LWIP_NETCONN_SEM_PER_THREAD
+    select_cb.sem = LWIP_NETCONN_THREAD_SEM_GET();
+#else /* LWIP_NETCONN_SEM_PER_THREAD */
+    if (sys_sem_new(&select_cb.sem, 0) != ERR_OK) {
+      /* failed to create semaphore */
+      set_errno(ENOMEM);
+      return -1;
+    }
+#endif /* LWIP_NETCONN_SEM_PER_THREAD */
+
+    /* Protect the select_cb_list */
+    SYS_ARCH_PROTECT(lev);
+
+    /* Put this select_cb on top of list */
+    select_cb.next = select_cb_list;
+    if (select_cb_list != NULL) {
+      select_cb_list->prev = &select_cb;
+    }
+    select_cb_list = &select_cb;
+    /* Increasing this counter tells event_callback that the list has changed. */
+    select_cb_ctr++;
+
+    /* Now we can safely unprotect */
+    SYS_ARCH_UNPROTECT(lev);
+
+    /* Increase select_waiting for each socket we are interested in */
+    maxfdp2 = maxfdp1;
+    for (i = LWIP_SOCKET_OFFSET; i < maxfdp1; i++) {
+      if ((readset && FD_ISSET(i, readset)) ||
+          (writeset && FD_ISSET(i, writeset)) ||
+          (exceptset && FD_ISSET(i, exceptset))) {
+        struct lwip_sock *sock;
+        SYS_ARCH_PROTECT(lev);
+        sock = tryget_socket(i);
+        if (sock != NULL) {
+          sock->select_waiting++;
+          LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
+        } else {
+          /* Not a valid socket */
+          nready = -1;
+          maxfdp2 = i;
+          SYS_ARCH_UNPROTECT(lev);
+          break;
+        }
+        SYS_ARCH_UNPROTECT(lev);
+      }
+    }
+
+    if (nready >= 0) {
+      /* Call lwip_selscan again: there could have been events between
+         the last scan (without us on the list) and putting us on the list! */
+      nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
+      if (!nready) {
+        /* Still none ready, just wait to be woken */
+        if (timeout == 0) {
+          /* Wait forever */
+          msectimeout = 0;
+        } else {
+          msectimeout =  ((timeout->tv_sec * 1000) + ((timeout->tv_usec + 500)/1000));
+          if (msectimeout == 0) {
+            /* Wait 1ms at least (0 means wait forever) */
+            msectimeout = 1;
+          }
+        }
+
+        waitres = sys_arch_sem_wait(SELECT_SEM_PTR(select_cb.sem), msectimeout);
+#if LWIP_NETCONN_SEM_PER_THREAD
+        waited = 1;
+#endif
+      }
+    }
+
+    /* Decrease select_waiting for each socket we are interested in */
+    for (i = LWIP_SOCKET_OFFSET; i < maxfdp2; i++) {
+      if ((readset && FD_ISSET(i, readset)) ||
+          (writeset && FD_ISSET(i, writeset)) ||
+          (exceptset && FD_ISSET(i, exceptset))) {
+        struct lwip_sock *sock;
+        SYS_ARCH_PROTECT(lev);
+        sock = tryget_socket(i);
+        if (sock != NULL) {
+          /* @todo: what if this is a new socket (reallocated?) in this case,
+             select_waiting-- would be wrong (a global 'sockalloc' counter,
+             stored per socket could help) */
+          LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
+          if (sock->select_waiting > 0) {
+            sock->select_waiting--;
+          }
+        } else {
+          /* Not a valid socket */
+          nready = -1;
+        }
+        SYS_ARCH_UNPROTECT(lev);
+      }
+    }
+    /* Take us off the list */
+    SYS_ARCH_PROTECT(lev);
+    if (select_cb.next != NULL) {
+      select_cb.next->prev = select_cb.prev;
+    }
+    if (select_cb_list == &select_cb) {
+      LWIP_ASSERT("select_cb.prev == NULL", select_cb.prev == NULL);
+      select_cb_list = select_cb.next;
+    } else {
+      LWIP_ASSERT("select_cb.prev != NULL", select_cb.prev != NULL);
+      select_cb.prev->next = select_cb.next;
+    }
+    /* Increasing this counter tells event_callback that the list has changed. */
+    select_cb_ctr++;
+    SYS_ARCH_UNPROTECT(lev);
+
+#if LWIP_NETCONN_SEM_PER_THREAD
+    if (select_cb.sem_signalled && (!waited || (waitres == SYS_ARCH_TIMEOUT))) {
+      /* don't leave the thread-local semaphore signalled */
+      sys_arch_sem_wait(select_cb.sem, 1);
+    }
+#else /* LWIP_NETCONN_SEM_PER_THREAD */
+    sys_sem_free(&select_cb.sem);
+#endif /* LWIP_NETCONN_SEM_PER_THREAD */
+
+    if (nready < 0) {
+      /* This happens when a socket got closed while waiting */
+      set_errno(EBADF);
+      return -1;
+    }
+
+    if (waitres == SYS_ARCH_TIMEOUT) {
+      /* Timeout */
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: timeout expired\n"));
+      /* This is OK as the local fdsets are empty and nready is zero,
+         or we would have returned earlier. */
+      goto return_copy_fdsets;
+    }
+
+    /* See what's set */
+    nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
+  }
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
+return_copy_fdsets:
+  set_errno(0);
+  if (readset) {
+    *readset = lreadset;
+  }
+  if (writeset) {
+    *writeset = lwriteset;
+  }
+  if (exceptset) {
+    *exceptset = lexceptset;
+  }
+  return nready;
+}
+
+/**
+ * Callback registered in the netconn layer for each socket-netconn.
+ * Processes recvevent (data available) and wakes up tasks waiting for select.
+ */
+static void
+event_callback(struct netconn *conn, enum netconn_evt evt, u16_t len)
+{
+  int s;
+  struct lwip_sock *sock;
+  struct lwip_select_cb *scb;
+  int last_select_cb_ctr;
+  SYS_ARCH_DECL_PROTECT(lev);
+
+  LWIP_UNUSED_ARG(len);
+
+  /* Get socket */
+  if (conn) {
+    s = conn->socket;
+    if (s < 0) {
+      /* Data comes in right away after an accept, even though
+       * the server task might not have created a new socket yet.
+       * Just count down (or up) if that's the case and we
+       * will use the data later. Note that only receive events
+       * can happen before the new socket is set up. */
+      SYS_ARCH_PROTECT(lev);
+      if (conn->socket < 0) {
+        if (evt == NETCONN_EVT_RCVPLUS) {
+          conn->socket--;
+        }
+        SYS_ARCH_UNPROTECT(lev);
+        return;
+      }
+      s = conn->socket;
+      SYS_ARCH_UNPROTECT(lev);
+    }
+
+    sock = get_socket(s);
+    if (!sock) {
+      return;
+    }
+  } else {
+    return;
+  }
+
+  SYS_ARCH_PROTECT(lev);
+  /* Set event as required */
+  switch (evt) {
+    case NETCONN_EVT_RCVPLUS:
+      sock->rcvevent++;
+      break;
+    case NETCONN_EVT_RCVMINUS:
+      sock->rcvevent--;
+      break;
+    case NETCONN_EVT_SENDPLUS:
+      sock->sendevent = 1;
+      break;
+    case NETCONN_EVT_SENDMINUS:
+      sock->sendevent = 0;
+      break;
+    case NETCONN_EVT_ERROR:
+      sock->errevent = 1;
+      break;
+    default:
+      LWIP_ASSERT("unknown event", 0);
+      break;
+  }
+
+  if (sock->select_waiting == 0) {
+    /* noone is waiting for this socket, no need to check select_cb_list */
+    SYS_ARCH_UNPROTECT(lev);
+    return;
+  }
+
+  /* Now decide if anyone is waiting for this socket */
+  /* NOTE: This code goes through the select_cb_list list multiple times
+     ONLY IF a select was actually waiting. We go through the list the number
+     of waiting select calls + 1. This list is expected to be small. */
+
+  /* At this point, SYS_ARCH is still protected! */
+again:
+  for (scb = select_cb_list; scb != NULL; scb = scb->next) {
+    /* remember the state of select_cb_list to detect changes */
+    last_select_cb_ctr = select_cb_ctr;
+    if (scb->sem_signalled == 0) {
+      /* semaphore not signalled yet */
+      int do_signal = 0;
+      /* Test this select call for our socket */
+      if (sock->rcvevent > 0) {
+        if (scb->readset && FD_ISSET(s, scb->readset)) {
+          do_signal = 1;
+        }
+      }
+      if (sock->sendevent != 0) {
+        if (!do_signal && scb->writeset && FD_ISSET(s, scb->writeset)) {
+          do_signal = 1;
+        }
+      }
+      if (sock->errevent != 0) {
+        if (!do_signal && scb->exceptset && FD_ISSET(s, scb->exceptset)) {
+          do_signal = 1;
+        }
+      }
+      if (do_signal) {
+        scb->sem_signalled = 1;
+        /* Don't call SYS_ARCH_UNPROTECT() before signaling the semaphore, as this might
+           lead to the select thread taking itself off the list, invalidating the semaphore. */
+        sys_sem_signal(SELECT_SEM_PTR(scb->sem));
+      }
+    }
+    /* unlock interrupts with each step */
+    SYS_ARCH_UNPROTECT(lev);
+    /* this makes sure interrupt protection time is short */
+    SYS_ARCH_PROTECT(lev);
+    if (last_select_cb_ctr != select_cb_ctr) {
+      /* someone has changed select_cb_list, restart at the beginning */
+      goto again;
+    }
+  }
+  SYS_ARCH_UNPROTECT(lev);
+}
+
+/**
+ * Unimplemented: Close one end of a full-duplex connection.
+ * Currently, the full connection is closed.
+ */
+int
+lwip_shutdown(int s, int how)
+{
+  struct lwip_sock *sock;
+  err_t err;
+  u8_t shut_rx = 0, shut_tx = 0;
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_shutdown(%d, how=%d)\n", s, how));
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  if (sock->conn != NULL) {
+    if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
+      sock_set_errno(sock, EOPNOTSUPP);
+      return -1;
+    }
+  } else {
+    sock_set_errno(sock, ENOTCONN);
+    return -1;
+  }
+
+  if (how == SHUT_RD) {
+    shut_rx = 1;
+  } else if (how == SHUT_WR) {
+    shut_tx = 1;
+  } else if (how == SHUT_RDWR) {
+    shut_rx = 1;
+    shut_tx = 1;
+  } else {
+    sock_set_errno(sock, EINVAL);
+    return -1;
+  }
+  err = netconn_shutdown(sock->conn, shut_rx, shut_tx);
+
+  sock_set_errno(sock, err_to_errno(err));
+  return (err == ERR_OK ? 0 : -1);
+}
+
+static int
+lwip_getaddrname(int s, struct sockaddr *name, socklen_t *namelen, u8_t local)
+{
+  struct lwip_sock *sock;
+  union sockaddr_aligned saddr;
+  ip_addr_t naddr;
+  u16_t port;
+  err_t err;
+
+  sock = get_socket(s);
+  if (!sock) {
+    return -1;
+  }
+
+  /* get the IP address and port */
+  /* @todo: this does not work for IPv6, yet */
+  err = netconn_getaddr(sock->conn, &naddr, &port, local);
+  if (err != ERR_OK) {
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+  IPADDR_PORT_TO_SOCKADDR(&saddr, &naddr, port);
+
+  LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getaddrname(%d, addr=", s));
+  ip_addr_debug_print_val(SOCKETS_DEBUG, naddr);
+  LWIP_DEBUGF(SOCKETS_DEBUG, (" port=%"U16_F")\n", port));
+
+  if (*namelen > saddr.sa.sa_len) {
+    *namelen = saddr.sa.sa_len;
+  }
+  MEMCPY(name, &saddr, *namelen);
+
+  sock_set_errno(sock, 0);
+  return 0;
+}
+
+int
+lwip_getpeername(int s, struct sockaddr *name, socklen_t *namelen)
+{
+  return lwip_getaddrname(s, name, namelen, 0);
+}
+
+int
+lwip_getsockname(int s, struct sockaddr *name, socklen_t *namelen)
+{
+  return lwip_getaddrname(s, name, namelen, 1);
+}
+
+int
+lwip_getsockopt(int s, int level, int optname, void *optval, socklen_t *optlen)
+{
+  u8_t err;
+  struct lwip_sock *sock = get_socket(s);
+#if !LWIP_TCPIP_CORE_LOCKING
+  LWIP_SETGETSOCKOPT_DATA_VAR_DECLARE(data);
+#endif /* !LWIP_TCPIP_CORE_LOCKING */
+
+  if (!sock) {
+    return -1;
+  }
+
+  if ((NULL == optval) || (NULL == optlen)) {
+    sock_set_errno(sock, EFAULT);
+    return -1;
+  }
+
+#if LWIP_TCPIP_CORE_LOCKING
+  /* core-locking can just call the -impl function */
+  LOCK_TCPIP_CORE();
+  err = lwip_getsockopt_impl(s, level, optname, optval, optlen);
+  UNLOCK_TCPIP_CORE();
+
+#else /* LWIP_TCPIP_CORE_LOCKING */
+
+#if LWIP_MPU_COMPATIBLE
+  /* MPU_COMPATIBLE copies the optval data, so check for max size here */
+  if (*optlen > LWIP_SETGETSOCKOPT_MAXOPTLEN) {
+    sock_set_errno(sock, ENOBUFS);
+    return -1;
+  }
+#endif /* LWIP_MPU_COMPATIBLE */
+
+  LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(data, sock);
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).s = s;
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).level = level;
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optname = optname;
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen = *optlen;
+#if !LWIP_MPU_COMPATIBLE
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval.p = optval;
+#endif /* !LWIP_MPU_COMPATIBLE */
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err = 0;
+#if LWIP_NETCONN_SEM_PER_THREAD
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
+#else
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = &sock->conn->op_completed;
+#endif
+  err = tcpip_callback(lwip_getsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));
+  if (err != ERR_OK) {
+    LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+  sys_arch_sem_wait((sys_sem_t*)(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem), 0);
+
+  /* write back optlen and optval */
+  *optlen = LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen;
+#if LWIP_MPU_COMPATIBLE
+  MEMCPY(optval, LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval,
+    LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen);
+#endif /* LWIP_MPU_COMPATIBLE */
+
+  /* maybe lwip_getsockopt_internal has changed err */
+  err = LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err;
+  LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
+#endif /* LWIP_TCPIP_CORE_LOCKING */
+
+  sock_set_errno(sock, err);
+  return err ? -1 : 0;
+}
+
+#if !LWIP_TCPIP_CORE_LOCKING
+/** lwip_getsockopt_callback: only used without CORE_LOCKING
+ * to get into the tcpip_thread
+ */
+static void
+lwip_getsockopt_callback(void *arg)
+{
+  struct lwip_setgetsockopt_data *data;
+  LWIP_ASSERT("arg != NULL", arg != NULL);
+  data = (struct lwip_setgetsockopt_data*)arg;
+
+  data->err = lwip_getsockopt_impl(data->s, data->level, data->optname,
+#if LWIP_MPU_COMPATIBLE
+    data->optval,
+#else /* LWIP_MPU_COMPATIBLE */
+    data->optval.p,
+#endif /* LWIP_MPU_COMPATIBLE */
+    &data->optlen);
+
+  sys_sem_signal((sys_sem_t*)(data->completed_sem));
+}
+#endif  /* LWIP_TCPIP_CORE_LOCKING */
+
+/** lwip_getsockopt_impl: the actual implementation of getsockopt:
+ * same argument as lwip_getsockopt, either called directly or through callback
+ */
+static u8_t
+lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *optlen)
+{
+  u8_t err = 0;
+  struct lwip_sock *sock = tryget_socket(s);
+  if (!sock) {
+    return EBADF;
+  }
+
+  switch (level) {
+
+/* Level: SOL_SOCKET */
+  case SOL_SOCKET:
+    switch (optname) {
+
+#if LWIP_TCP
+    case SO_ACCEPTCONN:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
+      if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_TCP) {
+        return ENOPROTOOPT;
+      }
+      if ((sock->conn->pcb.tcp != NULL) && (sock->conn->pcb.tcp->state == LISTEN)) {
+        *(int*)optval = 1;
+      } else {
+        *(int*)optval = 0;
+      }
+      break;
+#endif /* LWIP_TCP */
+
+    /* The option flags */
+    case SO_BROADCAST:
+    case SO_KEEPALIVE:
+#if SO_REUSE
+    case SO_REUSEADDR:
+#endif /* SO_REUSE */
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
+      *(int*)optval = ip_get_option(sock->conn->pcb.ip, optname);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, optname=0x%x, ..) = %s\n",
+                                  s, optname, (*(int*)optval?"on":"off")));
+      break;
+
+    case SO_TYPE:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, int);
+      switch (NETCONNTYPE_GROUP(netconn_type(sock->conn))) {
+      case NETCONN_RAW:
+        *(int*)optval = SOCK_RAW;
+        break;
+      case NETCONN_TCP:
+        *(int*)optval = SOCK_STREAM;
+        break;
+      case NETCONN_UDP:
+        *(int*)optval = SOCK_DGRAM;
+        break;
+      default: /* unrecognized socket type */
+        *(int*)optval = netconn_type(sock->conn);
+        LWIP_DEBUGF(SOCKETS_DEBUG,
+                    ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE): unrecognized socket type %d\n",
+                    s, *(int *)optval));
+      }  /* switch (netconn_type(sock->conn)) */
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, SO_TYPE) = %d\n",
+                  s, *(int *)optval));
+      break;
+
+    case SO_ERROR:
+      LWIP_SOCKOPT_CHECK_OPTLEN(*optlen, int);
+      /* only overwrite ERR_OK or temporary errors */
+      if (((sock->err == 0) || (sock->err == EINPROGRESS)) && (sock->conn != NULL)) {
+        sock_set_errno(sock, err_to_errno(sock->conn->last_err));
+      }
+      *(int *)optval = (sock->err == 0xFF ? (int)-1 : (int)sock->err);
+      sock->err = 0;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, SO_ERROR) = %d\n",
+                  s, *(int *)optval));
+      break;
+
+#if LWIP_SO_SNDTIMEO
+    case SO_SNDTIMEO:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
+      LWIP_SO_SNDRCVTIMEO_SET(optval, netconn_get_sendtimeout(sock->conn));
+      break;
+#endif /* LWIP_SO_SNDTIMEO */
+#if LWIP_SO_RCVTIMEO
+    case SO_RCVTIMEO:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
+      LWIP_SO_SNDRCVTIMEO_SET(optval, netconn_get_recvtimeout(sock->conn));
+      break;
+#endif /* LWIP_SO_RCVTIMEO */
+#if LWIP_SO_RCVBUF
+    case SO_RCVBUF:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, int);
+      *(int *)optval = netconn_get_recvbufsize(sock->conn);
+      break;
+#endif /* LWIP_SO_RCVBUF */
+#if LWIP_SO_LINGER
+    case SO_LINGER:
+      {
+        s16_t conn_linger;
+        struct linger* linger = (struct linger*)optval;
+        LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, struct linger);
+        conn_linger = sock->conn->linger;
+        if (conn_linger >= 0) {
+          linger->l_onoff = 1;
+          linger->l_linger = (int)conn_linger;
+        } else {
+          linger->l_onoff = 0;
+          linger->l_linger = 0;
+        }
+      }
+      break;
+#endif /* LWIP_SO_LINGER */
+#if LWIP_UDP
+    case SO_NO_CHECK:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, *optlen, int, NETCONN_UDP);
+#if LWIP_UDPLITE
+      if ((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0) {
+        /* this flag is only available for UDP, not for UDP lite */
+        return EAFNOSUPPORT;
+      }
+#endif /* LWIP_UDPLITE */
+      *(int*)optval = (udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_NOCHKSUM) ? 1 : 0;
+      break;
+#endif /* LWIP_UDP*/
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+
+/* Level: IPPROTO_IP */
+  case IPPROTO_IP:
+    switch (optname) {
+    case IP_TTL:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
+      *(int*)optval = sock->conn->pcb.ip->ttl;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TTL) = %d\n",
+                  s, *(int *)optval));
+      break;
+    case IP_TOS:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
+      *(int*)optval = sock->conn->pcb.ip->tos;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TOS) = %d\n",
+                  s, *(int *)optval));
+      break;
+#if LWIP_MULTICAST_TX_OPTIONS
+    case IP_MULTICAST_TTL:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, u8_t);
+      if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_UDP) {
+        return ENOPROTOOPT;
+      }
+      *(u8_t*)optval = udp_get_multicast_ttl(sock->conn->pcb.udp);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_TTL) = %d\n",
+                  s, *(int *)optval));
+      break;
+    case IP_MULTICAST_IF:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, struct in_addr);
+      if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_UDP) {
+        return ENOPROTOOPT;
+      }
+      inet_addr_from_ipaddr((struct in_addr*)optval, udp_get_multicast_netif_addr(sock->conn->pcb.udp));
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_IF) = 0x%"X32_F"\n",
+                  s, *(u32_t *)optval));
+      break;
+    case IP_MULTICAST_LOOP:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, u8_t);
+      if ((sock->conn->pcb.udp->flags & UDP_FLAGS_MULTICAST_LOOP) != 0) {
+        *(u8_t*)optval = 1;
+      } else {
+        *(u8_t*)optval = 0;
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_LOOP) = %d\n",
+                  s, *(int *)optval));
+      break;
+#endif /* LWIP_MULTICAST_TX_OPTIONS */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+
+#if LWIP_TCP
+/* Level: IPPROTO_TCP */
+  case IPPROTO_TCP:
+    /* Special case: all IPPROTO_TCP option take an int */
+    LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, *optlen, int, NETCONN_TCP);
+    switch (optname) {
+    case TCP_NODELAY:
+      *(int*)optval = tcp_nagle_disabled(sock->conn->pcb.tcp);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_NODELAY) = %s\n",
+                  s, (*(int*)optval)?"on":"off") );
+      break;
+    case TCP_KEEPALIVE:
+      *(int*)optval = (int)sock->conn->pcb.tcp->keep_idle;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPALIVE) = %d\n",
+                  s, *(int *)optval));
+      break;
+
+#if LWIP_TCP_KEEPALIVE
+    case TCP_KEEPIDLE:
+      *(int*)optval = (int)(sock->conn->pcb.tcp->keep_idle/1000);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPIDLE) = %d\n",
+                  s, *(int *)optval));
+      break;
+    case TCP_KEEPINTVL:
+      *(int*)optval = (int)(sock->conn->pcb.tcp->keep_intvl/1000);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPINTVL) = %d\n",
+                  s, *(int *)optval));
+      break;
+    case TCP_KEEPCNT:
+      *(int*)optval = (int)sock->conn->pcb.tcp->keep_cnt;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, TCP_KEEPCNT) = %d\n",
+                  s, *(int *)optval));
+      break;
+#endif /* LWIP_TCP_KEEPALIVE */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+#endif /* LWIP_TCP */
+
+#if LWIP_IPV6
+/* Level: IPPROTO_IPV6 */
+  case IPPROTO_IPV6:
+    switch (optname) {
+    case IPV6_V6ONLY:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, *optlen, int);
+      /* @todo: this does not work for datagram sockets, yet */
+      if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_TCP) {
+        return ENOPROTOOPT;
+      }
+      *(int*)optval = (netconn_get_ipv6only(sock->conn) ? 1 : 0);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IPV6, IPV6_V6ONLY) = %d\n",
+                  s, *(int *)optval));
+      break;
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IPV6, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+#endif /* LWIP_IPV6 */
+
+#if LWIP_UDP && LWIP_UDPLITE
+  /* Level: IPPROTO_UDPLITE */
+  case IPPROTO_UDPLITE:
+    /* Special case: all IPPROTO_UDPLITE option take an int */
+    LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, *optlen, int);
+    /* If this is no UDP lite socket, ignore any options. */
+    if (!NETCONNTYPE_ISUDPLITE(netconn_type(sock->conn))) {
+      return ENOPROTOOPT;
+    }
+    switch (optname) {
+    case UDPLITE_SEND_CSCOV:
+      *(int*)optval = sock->conn->pcb.udp->chksum_len_tx;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV) = %d\n",
+                  s, (*(int*)optval)) );
+      break;
+    case UDPLITE_RECV_CSCOV:
+      *(int*)optval = sock->conn->pcb.udp->chksum_len_rx;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV) = %d\n",
+                  s, (*(int*)optval)) );
+      break;
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_UDPLITE, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+#endif /* LWIP_UDP */
+  /* Level: IPPROTO_RAW */
+  case IPPROTO_RAW:
+    switch (optname) {
+#if LWIP_IPV6 && LWIP_RAW
+    case IPV6_CHECKSUM:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, *optlen, int, NETCONN_RAW);
+      if (sock->conn->pcb.raw->chksum_reqd == 0) {
+        *(int *)optval = -1;
+      } else {
+        *(int *)optval = sock->conn->pcb.raw->chksum_offset;
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_RAW, IPV6_CHECKSUM) = %d\n",
+                  s, (*(int*)optval)) );
+      break;
+#endif /* LWIP_IPV6 && LWIP_RAW */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_RAW, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+  default:
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n",
+                                s, level, optname));
+    err = ENOPROTOOPT;
+    break;
+  } /* switch (level) */
+
+  return err;
+}
+
+int
+lwip_setsockopt(int s, int level, int optname, const void *optval, socklen_t optlen)
+{
+  u8_t err = 0;
+  struct lwip_sock *sock = get_socket(s);
+#if !LWIP_TCPIP_CORE_LOCKING
+  LWIP_SETGETSOCKOPT_DATA_VAR_DECLARE(data);
+#endif /* !LWIP_TCPIP_CORE_LOCKING */
+
+  if (!sock) {
+    return -1;
+  }
+
+  if (NULL == optval) {
+    sock_set_errno(sock, EFAULT);
+    return -1;
+  }
+
+#if LWIP_TCPIP_CORE_LOCKING
+  /* core-locking can just call the -impl function */
+  LOCK_TCPIP_CORE();
+  err = lwip_setsockopt_impl(s, level, optname, optval, optlen);
+  UNLOCK_TCPIP_CORE();
+
+#else /* LWIP_TCPIP_CORE_LOCKING */
+
+#if LWIP_MPU_COMPATIBLE
+  /* MPU_COMPATIBLE copies the optval data, so check for max size here */
+  if (optlen > LWIP_SETGETSOCKOPT_MAXOPTLEN) {
+    sock_set_errno(sock, ENOBUFS);
+    return -1;
+  }
+#endif /* LWIP_MPU_COMPATIBLE */
+
+  LWIP_SETGETSOCKOPT_DATA_VAR_ALLOC(data, sock);
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).s = s;
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).level = level;
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optname = optname;
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optlen = optlen;
+#if LWIP_MPU_COMPATIBLE
+  MEMCPY(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval, optval, optlen);
+#else /* LWIP_MPU_COMPATIBLE */
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).optval.pc = (const void*)optval;
+#endif /* LWIP_MPU_COMPATIBLE */
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err = 0;
+#if LWIP_NETCONN_SEM_PER_THREAD
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
+#else
+  LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = &sock->conn->op_completed;
+#endif
+  err = tcpip_callback(lwip_setsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));
+  if (err != ERR_OK) {
+    LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
+  sys_arch_sem_wait((sys_sem_t*)(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem), 0);
+
+  /* maybe lwip_getsockopt_internal has changed err */
+  err = LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).err;
+  LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
+#endif  /* LWIP_TCPIP_CORE_LOCKING */
+
+  sock_set_errno(sock, err);
+  return err ? -1 : 0;
+}
+
+#if !LWIP_TCPIP_CORE_LOCKING
+/** lwip_setsockopt_callback: only used without CORE_LOCKING
+ * to get into the tcpip_thread
+ */
+static void
+lwip_setsockopt_callback(void *arg)
+{
+  struct lwip_setgetsockopt_data *data;
+  LWIP_ASSERT("arg != NULL", arg != NULL);
+  data = (struct lwip_setgetsockopt_data*)arg;
+
+  data->err = lwip_setsockopt_impl(data->s, data->level, data->optname,
+#if LWIP_MPU_COMPATIBLE
+    data->optval,
+#else /* LWIP_MPU_COMPATIBLE */
+    data->optval.pc,
+#endif /* LWIP_MPU_COMPATIBLE */
+    data->optlen);
+
+  sys_sem_signal((sys_sem_t*)(data->completed_sem));
+}
+#endif  /* LWIP_TCPIP_CORE_LOCKING */
+
+/** lwip_setsockopt_impl: the actual implementation of setsockopt:
+ * same argument as lwip_setsockopt, either called directly or through callback
+ */
+static u8_t
+lwip_setsockopt_impl(int s, int level, int optname, const void *optval, socklen_t optlen)
+{
+  u8_t err = 0;
+  struct lwip_sock *sock = tryget_socket(s);
+  if (!sock) {
+    return EBADF;
+  }
+
+  switch (level) {
+
+/* Level: SOL_SOCKET */
+  case SOL_SOCKET:
+    switch (optname) {
+
+    /* SO_ACCEPTCONN is get-only */
+
+    /* The option flags */
+    case SO_BROADCAST:
+    case SO_KEEPALIVE:
+#if SO_REUSE
+    case SO_REUSEADDR:
+#endif /* SO_REUSE */
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);
+      if (*(const int*)optval) {
+        ip_set_option(sock->conn->pcb.ip, optname);
+      } else {
+        ip_reset_option(sock->conn->pcb.ip, optname);
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, SOL_SOCKET, optname=0x%x, ..) -> %s\n",
+                  s, optname, (*(const int*)optval?"on":"off")));
+      break;
+
+    /* SO_TYPE is get-only */
+    /* SO_ERROR is get-only */
+
+#if LWIP_SO_SNDTIMEO
+    case SO_SNDTIMEO:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
+      netconn_set_sendtimeout(sock->conn, LWIP_SO_SNDRCVTIMEO_GET_MS(optval));
+      break;
+#endif /* LWIP_SO_SNDTIMEO */
+#if LWIP_SO_RCVTIMEO
+    case SO_RCVTIMEO:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, LWIP_SO_SNDRCVTIMEO_OPTTYPE);
+      netconn_set_recvtimeout(sock->conn, (int)LWIP_SO_SNDRCVTIMEO_GET_MS(optval));
+      break;
+#endif /* LWIP_SO_RCVTIMEO */
+#if LWIP_SO_RCVBUF
+    case SO_RCVBUF:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, int);
+      netconn_set_recvbufsize(sock->conn, *(const int*)optval);
+      break;
+#endif /* LWIP_SO_RCVBUF */
+#if LWIP_SO_LINGER
+    case SO_LINGER:
+      {
+        const struct linger* linger = (const struct linger*)optval;
+        LWIP_SOCKOPT_CHECK_OPTLEN_CONN(sock, optlen, struct linger);
+        if (linger->l_onoff) {
+          int lingersec = linger->l_linger;
+          if (lingersec < 0) {
+            return EINVAL;
+          }
+          if (lingersec > 0xFFFF) {
+            lingersec = 0xFFFF;
+          }
+          sock->conn->linger = (s16_t)lingersec;
+        } else {
+          sock->conn->linger = -1;
+        }
+      }
+      break;
+#endif /* LWIP_SO_LINGER */
+#if LWIP_UDP
+    case SO_NO_CHECK:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_UDP);
+#if LWIP_UDPLITE
+      if ((udp_flags(sock->conn->pcb.udp) & UDP_FLAGS_UDPLITE) != 0) {
+        /* this flag is only available for UDP, not for UDP lite */
+        return EAFNOSUPPORT;
+      }
+#endif /* LWIP_UDPLITE */
+      if (*(const int*)optval) {
+        udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_NOCHKSUM);
+      } else {
+        udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_NOCHKSUM);
+      }
+      break;
+#endif /* LWIP_UDP */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, SOL_SOCKET, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+
+/* Level: IPPROTO_IP */
+  case IPPROTO_IP:
+    switch (optname) {
+    case IP_TTL:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);
+      sock->conn->pcb.ip->ttl = (u8_t)(*(const int*)optval);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TTL, ..) -> %d\n",
+                  s, sock->conn->pcb.ip->ttl));
+      break;
+    case IP_TOS:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);
+      sock->conn->pcb.ip->tos = (u8_t)(*(const int*)optval);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, IP_TOS, ..)-> %d\n",
+                  s, sock->conn->pcb.ip->tos));
+      break;
+#if LWIP_MULTICAST_TX_OPTIONS
+    case IP_MULTICAST_TTL:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, u8_t, NETCONN_UDP);
+      udp_set_multicast_ttl(sock->conn->pcb.udp, (u8_t)(*(const u8_t*)optval));
+      break;
+    case IP_MULTICAST_IF:
+      {
+        ip4_addr_t if_addr;
+        LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, struct in_addr, NETCONN_UDP);
+        inet_addr_to_ipaddr(&if_addr, (const struct in_addr*)optval);
+        udp_set_multicast_netif_addr(sock->conn->pcb.udp, &if_addr);
+      }
+      break;
+    case IP_MULTICAST_LOOP:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, u8_t, NETCONN_UDP);
+      if (*(const u8_t*)optval) {
+        udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) | UDP_FLAGS_MULTICAST_LOOP);
+      } else {
+        udp_setflags(sock->conn->pcb.udp, udp_flags(sock->conn->pcb.udp) & ~UDP_FLAGS_MULTICAST_LOOP);
+      }
+      break;
+#endif /* LWIP_MULTICAST_TX_OPTIONS */
+#if LWIP_IGMP
+    case IP_ADD_MEMBERSHIP:
+    case IP_DROP_MEMBERSHIP:
+      {
+        /* If this is a TCP or a RAW socket, ignore these options. */
+        /* @todo: assign membership to this socket so that it is dropped when closing the socket */
+        err_t igmp_err;
+        const struct ip_mreq *imr = (const struct ip_mreq *)optval;
+        ip4_addr_t if_addr;
+        ip4_addr_t multi_addr;
+        LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, struct ip_mreq, NETCONN_UDP);
+        inet_addr_to_ipaddr(&if_addr, &imr->imr_interface);
+        inet_addr_to_ipaddr(&multi_addr, &imr->imr_multiaddr);
+        if (optname == IP_ADD_MEMBERSHIP) {
+          if (!lwip_socket_register_membership(s, &if_addr, &multi_addr)) {
+            /* cannot track membership (out of memory) */
+            err = ENOMEM;
+            igmp_err = ERR_OK;
+          } else {
+            igmp_err = igmp_joingroup(&if_addr, &multi_addr);
+          }
+        } else {
+          igmp_err = igmp_leavegroup(&if_addr, &multi_addr);
+          lwip_socket_unregister_membership(s, &if_addr, &multi_addr);
+        }
+        if (igmp_err != ERR_OK) {
+          err = EADDRNOTAVAIL;
+        }
+      }
+      break;
+#endif /* LWIP_IGMP */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+
+#if LWIP_TCP
+/* Level: IPPROTO_TCP */
+  case IPPROTO_TCP:
+    /* Special case: all IPPROTO_TCP option take an int */
+    LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_TCP);
+    switch (optname) {
+    case TCP_NODELAY:
+      if (*(const int*)optval) {
+        tcp_nagle_disable(sock->conn->pcb.tcp);
+      } else {
+        tcp_nagle_enable(sock->conn->pcb.tcp);
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_NODELAY) -> %s\n",
+                  s, (*(const int *)optval)?"on":"off") );
+      break;
+    case TCP_KEEPALIVE:
+      sock->conn->pcb.tcp->keep_idle = (u32_t)(*(const int*)optval);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPALIVE) -> %"U32_F"\n",
+                  s, sock->conn->pcb.tcp->keep_idle));
+      break;
+
+#if LWIP_TCP_KEEPALIVE
+    case TCP_KEEPIDLE:
+      sock->conn->pcb.tcp->keep_idle = 1000*(u32_t)(*(const int*)optval);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPIDLE) -> %"U32_F"\n",
+                  s, sock->conn->pcb.tcp->keep_idle));
+      break;
+    case TCP_KEEPINTVL:
+      sock->conn->pcb.tcp->keep_intvl = 1000*(u32_t)(*(const int*)optval);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPINTVL) -> %"U32_F"\n",
+                  s, sock->conn->pcb.tcp->keep_intvl));
+      break;
+    case TCP_KEEPCNT:
+      sock->conn->pcb.tcp->keep_cnt = (u32_t)(*(const int*)optval);
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, TCP_KEEPCNT) -> %"U32_F"\n",
+                  s, sock->conn->pcb.tcp->keep_cnt));
+      break;
+#endif /* LWIP_TCP_KEEPALIVE */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_TCP, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+#endif /* LWIP_TCP*/
+
+#if LWIP_IPV6
+/* Level: IPPROTO_IPV6 */
+  case IPPROTO_IPV6:
+    switch (optname) {
+    case IPV6_V6ONLY:
+      /* @todo: this does not work for datagram sockets, yet */
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_TCP);
+      if (*(const int*)optval) {
+        netconn_set_ipv6only(sock->conn, 1);
+      } else {
+        netconn_set_ipv6only(sock->conn, 0);
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IPV6, IPV6_V6ONLY, ..) -> %d\n",
+                  s, (netconn_get_ipv6only(sock->conn) ? 1 : 0)));
+      break;
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_IPV6, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+#endif /* LWIP_IPV6 */
+
+#if LWIP_UDP && LWIP_UDPLITE
+  /* Level: IPPROTO_UDPLITE */
+  case IPPROTO_UDPLITE:
+    /* Special case: all IPPROTO_UDPLITE option take an int */
+    LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB(sock, optlen, int);
+    /* If this is no UDP lite socket, ignore any options. */
+    if (!NETCONNTYPE_ISUDPLITE(netconn_type(sock->conn))) {
+      return ENOPROTOOPT;
+    }
+    switch (optname) {
+    case UDPLITE_SEND_CSCOV:
+      if ((*(const int*)optval != 0) && ((*(const int*)optval < 8) || (*(const int*)optval > 0xffff))) {
+        /* don't allow illegal values! */
+        sock->conn->pcb.udp->chksum_len_tx = 8;
+      } else {
+        sock->conn->pcb.udp->chksum_len_tx = (u16_t)*(const int*)optval;
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV) -> %d\n",
+                  s, (*(const int*)optval)) );
+      break;
+    case UDPLITE_RECV_CSCOV:
+      if ((*(const int*)optval != 0) && ((*(const int*)optval < 8) || (*(const int*)optval > 0xffff))) {
+        /* don't allow illegal values! */
+        sock->conn->pcb.udp->chksum_len_rx = 8;
+      } else {
+        sock->conn->pcb.udp->chksum_len_rx = (u16_t)*(const int*)optval;
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV) -> %d\n",
+                  s, (*(const int*)optval)) );
+      break;
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_UDPLITE, UNIMPL: optname=0x%x, ..)\n",
+                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+#endif /* LWIP_UDP */
+  /* Level: IPPROTO_RAW */
+  case IPPROTO_RAW:
+    switch (optname) {
+#if LWIP_IPV6 && LWIP_RAW
+    case IPV6_CHECKSUM:
+      LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, int, NETCONN_RAW);
+      if (*(const int *)optval < 0) {
+        sock->conn->pcb.raw->chksum_reqd = 0;
+      } else if (*(const int *)optval & 1) {
+        /* Per RFC3542, odd offsets are not allowed */
+        return EINVAL;
+      } else {
+        sock->conn->pcb.raw->chksum_reqd = 1;
+        sock->conn->pcb.raw->chksum_offset = (u16_t)*(const int *)optval;
+      }
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_RAW, IPV6_CHECKSUM, ..) -> %d\n",
+                  s, sock->conn->pcb.raw->chksum_reqd));
+      break;
+#endif /* LWIP_IPV6 && LWIP_RAW */
+    default:
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, IPPROTO_RAW, UNIMPL: optname=0x%x, ..)\n",
+                                  s, optname));
+      err = ENOPROTOOPT;
+      break;
+    }  /* switch (optname) */
+    break;
+  default:
+    LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_setsockopt(%d, level=0x%x, UNIMPL: optname=0x%x, ..)\n",
+                s, level, optname));
+    err = ENOPROTOOPT;
+    break;
+  }  /* switch (level) */
+
+  return err;
+}
+
+int
+lwip_ioctl(int s, long cmd, void *argp)
+{
+  struct lwip_sock *sock = get_socket(s);
+  u8_t val;
+#if LWIP_SO_RCVBUF
+  u16_t buflen = 0;
+  int recv_avail;
+#endif /* LWIP_SO_RCVBUF

<TRUNCATED>