apps/examples/netloop: Add a test of the local loopback device

ChangeLog.txt

@@ -1423,3 +1423,6 @@
 	* apps/nshlib: Fix error handling in 'mv' command.  On a failure to
 	  expand the second path, the memory allocated for the expansion of the
 	  first path was not being freed.  From Bruno Herrera (2015-08-26).
+	* apps/examples/netloop:  Add a test of the local loopback device
+	  (2015-09-02).
+

examples/Kconfig

@@ -34,6 +34,7 @@ source "$APPSDIR/examples/modbus/Kconfig"
 source "$APPSDIR/examples/mount/Kconfig"
 source "$APPSDIR/examples/mtdpart/Kconfig"
 source "$APPSDIR/examples/mtdrwb/Kconfig"
+source "$APPSDIR/examples/netloop/Kconfig"
 source "$APPSDIR/examples/netpkt/Kconfig"
 source "$APPSDIR/examples/nettest/Kconfig"
 source "$APPSDIR/examples/nrf24l01_term/Kconfig"

examples/README.txt

@@ -794,6 +794,23 @@ examples/netpkt
 
   A test of AF_PACKET, "raw" sockets.  Contributed by Lazlo Sitzer.
 
+examples/netloop
+^^^^^^^^^^^^^^^^
+
+  This is a simple test of the netwok loopback device
+
+    CONFIG_EXAMPLES_NETLOOP=y - Enables the nettest example
+
+  Dependencies:
+
+    CONFIG_NSH_BUILTIN_APPS=n
+    CONFIG_NET_LOOPBACK
+    CONFIG_NET_TCP
+    CONFIG_NET_TCPBACKLOG
+    CONFIG_NET_TCP_READAHEAD
+    CONFIG_NET_TCP_WRITE_BUFFERS
+    CONFIG_NET_IPv4
+
 examples/nettest
 ^^^^^^^^^^^^^^^^
 

examples/netloop/.gitignore

@@ -0,0 +1,14 @@
+/Make.dep
+/.depend
+/.built
+/host
+/*.asm
+/*.obj
+/*.rel
+/*.lst
+/*.sym
+/*.adb
+/*.lib
+/*.src
+/*.exe
+/*.dSYM

examples/netloop/Kconfig

@@ -0,0 +1,14 @@
+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#
+
+config EXAMPLES_NETLOOP
+	bool "Local loopback example"
+	default n
+	depends on !NSH_BUILTIN_APPS && NET_LOOPBACK && NET_TCP && NET_TCPBACKLOG && NET_TCP_READAHEAD && NET_TCP_WRITE_BUFFERS && NET_IPv4
+	---help---
+		Enable the local loopback example
+
+if EXAMPLES_NETLOOP
+endif # EXAMPLES_NETLOOP

examples/netloop/Make.defs

@@ -0,0 +1,38 @@
+############################################################################
+# apps/examples/netloop/Make.defs
+#
+#   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# 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. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "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
+# COPYRIGHT OWNER OR CONTRIBUTORS 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.
+#
+############################################################################
+
+ifeq ($(CONFIG_EXAMPLES_NETLOOP),y)
+CONFIGURED_APPS += examples/netloop
+endif

examples/netloop/Makefile

@@ -0,0 +1,127 @@
+############################################################################
+# apps/examples/netloop/Makefile
+#
+#   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <gnutt@nuttx.org>
+#
+# 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. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "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
+# COPYRIGHT OWNER OR CONTRIBUTORS 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.
+#
+############################################################################
+
+-include $(TOPDIR)/.config
+-include $(TOPDIR)/Make.defs
+include $(APPDIR)/Make.defs
+
+# Device Driver poll()/select() Example
+
+ASRCS =
+CSRCS = lo_listener.c
+MAINSRC = lo_main.c
+
+AOBJS = $(ASRCS:.S=$(OBJEXT))
+COBJS = $(CSRCS:.c=$(OBJEXT))
+MAINOBJ = $(MAINSRC:.c=$(OBJEXT))
+
+SRCS = $(ASRCS) $(CSRCS) $(MAINSRC)
+OBJS = $(AOBJS) $(COBJS)
+
+ifneq ($(CONFIG_BUILD_KERNEL),y)
+  OBJS += $(MAINOBJ)
+endif
+
+ifeq ($(CONFIG_WINDOWS_NATIVE),y)
+  BIN = ..\..\libapps$(LIBEXT)
+else
+ifeq ($(WINTOOL),y)
+  BIN = ..\\..\\libapps$(LIBEXT)
+else
+  BIN = ../../libapps$(LIBEXT)
+endif
+endif
+
+ifeq ($(WINTOOL),y)
+  INSTALL_DIR = "${shell cygpath -w $(BIN_DIR)}"
+else
+  INSTALL_DIR = $(BIN_DIR)
+endif
+
+CONFIG_XYZ_PROGNAME ?= poll$(EXEEXT)
+PROGNAME = $(CONFIG_XYZ_PROGNAME)
+
+ROOTDEPPATH = --dep-path .
+
+# Common build
+
+VPATH =
+
+all: .built
+.PHONY: clean depend distclean
+
+$(AOBJS): %$(OBJEXT): %.S
+	$(call ASSEMBLE, $<, $@)
+
+$(COBJS) $(MAINOBJ): %$(OBJEXT): %.c
+	$(call COMPILE, $<, $@)
+
+.built: $(OBJS)
+	$(call ARCHIVE, $(BIN), $(OBJS))
+	@touch .built
+
+ifeq ($(CONFIG_BUILD_KERNEL),y)
+$(BIN_DIR)$(DELIM)$(PROGNAME): $(OBJS) $(MAINOBJ)
+	@echo "LD: $(PROGNAME)"
+	$(Q) $(LD) $(LDELFFLAGS) $(LDLIBPATH) -o $(INSTALL_DIR)$(DELIM)$(PROGNAME) $(ARCHCRT0OBJ) $(MAINOBJ) $(LDLIBS)
+	$(Q) $(NM) -u  $(INSTALL_DIR)$(DELIM)$(PROGNAME)
+
+install: $(BIN_DIR)$(DELIM)$(PROGNAME)
+
+else
+install:
+
+endif
+
+context:
+
+.depend: Makefile $(SRCS)
+	@$(MKDEP) $(ROOTDEPPATH) "$(CC)" -- $(CFLAGS) -- $(SRCS) >Make.dep
+	@touch $@
+
+# Register application
+depend: .depend
+
+clean:
+	$(call DELFILE, .built)
+	$(call CLEAN)
+
+distclean: clean
+	$(call DELFILE, Make.dep)
+	$(call DELFILE, .depend)
+	$(call DELFILE, host$(HOSTEXEEXT))
+	$(call DELFILE, *.dSYM)
+
+-include Make.dep

examples/netloop/lo_listener.c

@@ -0,0 +1,392 @@
+/****************************************************************************
+ * examples/netloop/lo_listener.c
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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
+ * COPYRIGHT OWNER OR CONTRIBUTORS 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/stat.h>
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <net/if.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#include <apps/netutils/netlib.h>
+
+#include "netloop.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define IOBUFFER_SIZE 80
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct net_listener_s
+{
+  struct sockaddr_in addr;
+  fd_set          master;
+  fd_set          working;
+  char            buffer[IOBUFFER_SIZE];
+  int             listensd;
+  int             mxsd;
+};
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: net_closeclient
+ ****************************************************************************/
+
+static bool net_closeclient(struct net_listener_s *nls, int sd)
+{
+  printf("lo_listener: Closing host side connection sd=%d\n", sd);
+  close(sd);
+  FD_CLR(sd, &nls->master);
+
+  /* If we just closed the max SD, then search downward for the next biggest SD. */
+
+  while (FD_ISSET(nls->mxsd, &nls->master) == false)
+    {
+      nls->mxsd -= 1;
+    }
+
+  return true;
+}
+
+/****************************************************************************
+ * Name: net_incomingdata
+ ****************************************************************************/
+
+static inline bool net_incomingdata(struct net_listener_s *nls, int sd)
+{
+  char *ptr;
+  int nbytes;
+  int ret;
+
+  /* Read data from the socket */
+
+#ifdef FIONBIO
+  for (;;)
+#endif
+    {
+      printf("lo_listener: Read data from sd=%d\n", sd);
+      ret = recv(sd, nls->buffer, IOBUFFER_SIZE, 0);
+      if (ret < 0)
+        {
+          if (errno != EINTR)
+            {
+              printf("lo_listener: recv failed sd=%d: %d\n", sd, errno);
+              if (errno != EAGAIN)
+                {
+                  net_closeclient(nls, sd);
+                  return false;
+                }
+            }
+        }
+      else if (ret == 0)
+        {
+          printf("lo_listener: Client connection lost sd=%d\n", sd);
+          net_closeclient(nls, sd);
+          return false;
+        }
+      else
+        {
+          nls->buffer[ret]='\0';
+          printf("poll_listener: Read '%s' (%d bytes)\n", nls->buffer, ret);
+
+          /* Echo the data back to the client */
+
+          for (nbytes = ret, ptr = nls->buffer; nbytes > 0; )
+            {
+              ret = send(sd, ptr, nbytes, 0);
+              if (ret < 0)
+                {
+                  if (errno != EINTR)
+                    {
+                       printf("lo_listener: Send failed sd=%d: %d\n", sd, errno);
+                       net_closeclient(nls, sd);
+                       return false;
+                    }
+                }
+              else
+                {
+                  nbytes -= ret;
+                  ptr    += ret;
+                }
+            }
+        }
+    }
+
+  return 0;
+}
+
+/****************************************************************************
+ * Name: net_connection
+ ****************************************************************************/
+
+static inline bool net_connection(struct net_listener_s *nls)
+{
+  int sd;
+
+  /* Loop until all connections have been processed */
+
+#ifdef FIONBIO
+  for (;;)
+#endif
+    {
+      printf("lo_listener: Accepting new connection on sd=%d\n", nls->listensd);
+
+      sd = accept(nls->listensd, NULL, NULL);
+      if (sd < 0)
+        {
+          printf("lo_listener: accept failed: %d\n", errno);
+
+          if (errno != EINTR)
+            {
+              return false;
+            }
+        }
+      else
+        {
+          /* Add the new connection to the master set */
+
+          printf("lo_listener: Connection accepted for sd=%d\n", sd);
+
+          FD_SET(sd, &nls->master);
+          if (sd > nls->mxsd)
+            {
+               nls->mxsd = sd;
+            }
+
+          return true;
+        }
+    }
+
+  return false;
+}
+
+/****************************************************************************
+ * Name: net_mksocket
+ ****************************************************************************/
+
+static inline bool net_mksocket(struct net_listener_s *nls)
+{
+  int value;
+  int ret;
+
+  /* Create a listening socket */
+
+  printf("lo_listener: Initializing listener socket\n");
+  nls->listensd = socket(AF_INET, SOCK_STREAM, 0);
+  if (nls->listensd < 0)
+    {
+      printf("lo_listener: socket failed: %d\n", errno);
+      return false;
+    }
+
+  /* Configure the socket */
+
+  value = 1;
+  ret = setsockopt(nls->listensd, SOL_SOCKET,  SO_REUSEADDR, (char*)&value, sizeof(int));
+  if (ret < 0)
+    {
+      printf("lo_listener: setsockopt failed: %d\n", errno);
+      close(nls->listensd);
+      return false;
+    }
+
+  /* Set the socket to non-blocking */
+
+#ifdef FIONBIO
+  ret = ioctl(nls->listensd, FIONBIO, (char *)&value);
+  if (ret < 0)
+    {
+      printf("lo_listener: ioctl failed: %d\n", errno);
+      close(nls->listensd);
+      return false;
+    }
+#endif
+
+  /* Bind the socket */
+
+  memset(&nls->addr, 0, sizeof(struct sockaddr_in));
+  nls->addr.sin_family      = AF_INET;
+  nls->addr.sin_port        = htons(LISTENER_PORT);
+  nls->addr.sin_addr.s_addr = htonl(LO_ADDRESS);
+  ret = bind(nls->listensd, (struct sockaddr *)&nls->addr, sizeof(struct sockaddr_in));
+  if (ret < 0)
+    {
+      printf("lo_listener: bind failed: %d\n", errno);
+      close(nls->listensd);
+      return false;
+    }
+
+  /* Mark the socket as a listener */
+
+  ret = listen(nls->listensd, 32);
+  if (ret < 0)
+    {
+      printf("lo_listener: bind failed: %d\n", errno);
+      close(nls->listensd);
+      return false;
+    }
+
+  return true;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lo_listener
+ ****************************************************************************/
+
+void *lo_listener(pthread_addr_t pvarg)
+{
+  struct net_listener_s nls;
+  struct timeval timeout;
+  int nsds;
+  int ret;
+  int i;
+
+  /* Set up a listening socket */
+
+  memset(&nls, 0, sizeof(struct net_listener_s));
+  if (!net_mksocket(&nls))
+    {
+       return (void*)1;
+    }
+
+  /* Initialize the 'master' file descriptor set */
+
+  FD_ZERO(&nls.master);
+  nls.mxsd = nls.listensd;
+  FD_SET(nls.listensd, &nls.master);
+
+  /* Set up a 3 second timeout */
+
+  timeout.tv_sec  = LISTENER_DELAY;
+  timeout.tv_usec = 0;
+
+  /* Loop waiting for incoming connections or for incoming data
+   * on any of the connect sockets.
+   */
+
+  for (;;)
+    {
+      /* Wait on select */
+
+      printf("lo_listener: Calling select(), listener sd=%d\n", nls.listensd);
+      memcpy(&nls.working, &nls.master, sizeof(fd_set));
+      ret = select(nls.mxsd + 1, (FAR fd_set*)&nls.working, (FAR fd_set*)NULL, (FAR fd_set*)NULL, &timeout);
+      if (ret < 0)
+        {
+          printf("lo_listener: select failed: %d\n", errno);
+          break;
+        }
+
+      /* Check for timeout */
+
+      if (ret == 0)
+        {
+          printf("lo_listener: Timeout\n");
+          continue;
+        }
+
+      /* Find which descriptors caused the wakeup */
+
+      nsds = ret;
+      for (i = 0; i <= nls.mxsd && nsds > 0; i++)
+        {
+          /* Is this descriptor ready? */
+
+          if (FD_ISSET(i, &nls.working))
+            {
+              /* Yes, is it our listener? */
+
+              printf("lo_listener: Activity on sd=%d\n", i);
+
+              nsds--;
+              if (i == nls.listensd)
+                {
+                  (void)net_connection(&nls);
+                }
+              else
+                {
+                  net_incomingdata(&nls, i);
+                }
+            }
+        }
+    }
+
+  /* Cleanup */
+
+#if 0 /* Don't get here */
+   for (i = 0; i <= nls.mxsd; +i++)
+    {
+      if (FD_ISSET(i, &nls.master))
+        {
+          close(i);
+        }
+    }
+#endif
+  return NULL;  /* Keeps some compilers from complaining */
+}

examples/netloop/lo_main.c

@@ -0,0 +1,209 @@
+/****************************************************************************
+ * examples/netloop/lo_main.c
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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
+ * COPYRIGHT OWNER OR CONTRIBUTORS 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#include "netloop.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define IOBUFFER_SIZE 80
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lo_client
+ ****************************************************************************/
+
+static int lo_client(void)
+{
+  struct sockaddr_in myaddr;
+  char outbuf[IOBUFFER_SIZE];
+  char inbuf[IOBUFFER_SIZE];
+  int sockfd;
+  int len;
+  int nbytessent;
+  int nbytesrecvd;
+  int ret;
+  int i;
+
+  /* Create a new TCP socket */
+
+  sockfd = socket(PF_INET, SOCK_STREAM, 0);
+  if (sockfd < 0)
+    {
+      ret = -errno;
+      printf("lo_client: socket failure %d\n", ret);
+      return ret;
+    }
+
+  /* Connect the socket to the server */
+
+  myaddr.sin_family      = AF_INET;
+  myaddr.sin_port        = htons(LISTENER_PORT);
+  myaddr.sin_addr.s_addr = htonl(LO_ADDRESS);
+
+  printf("lo_client: Connecting to %08x:%d...\n", LO_ADDRESS, LISTENER_PORT);
+  if (connect( sockfd, (struct sockaddr*)&myaddr, sizeof(struct sockaddr_in)) < 0)
+    {
+      ret = -errno;
+      printf("lo_client: connect failure: %d\n", ret);
+      goto errout_with_socket;
+    }
+  printf("lo_client: Connected\n");
+
+  /* Then send and receive messages */
+
+  for (i = 0; ; i++)
+    {
+      sprintf(outbuf, "Remote message %d", i);
+      len = strlen(outbuf);
+
+      printf("lo_client: Sending '%s' (%d bytes)\n", outbuf, len);
+      nbytessent = send(sockfd, outbuf, len, 0);
+      printf("lo_client: Sent %d bytes\n", nbytessent);
+
+      if (nbytessent < 0)
+        {
+          ret = -errno;
+          printf("lo_client: send failed: %d\n", ret);
+          goto errout_with_socket;
+        }
+      else if (nbytessent != len)
+        {
+          ret = -EINVAL;
+          printf("lo_client: Bad send length: %d Expected: %d\n", nbytessent, len);
+          goto errout_with_socket;
+        }
+
+      printf("lo_client: Receiving...\n");
+      nbytesrecvd = recv(sockfd, inbuf, IOBUFFER_SIZE, 0);
+
+      if (nbytesrecvd < 0)
+        {
+          ret = -errno;
+          printf("lo_client: recv failed: %d\n", ret);
+          goto errout_with_socket;
+        }
+      else if (nbytesrecvd == 0)
+        {
+          ret = -ENOTCONN;
+          printf("lo_client: The server broke the connections\n");
+          goto errout_with_socket;
+        }
+
+      inbuf[nbytesrecvd] = '\0';
+      printf("lo_client: Received '%s' (%d bytes)\n", inbuf, nbytesrecvd);
+
+      if (nbytesrecvd != len)
+        {
+          ret = -EINVAL;
+          printf("lo_client: Bad recv length: %d Expected: %d\n", nbytesrecvd, len);
+          goto errout_with_socket;
+        }
+      else if (memcmp(inbuf, outbuf, len) != 0)
+        {
+          ret = -EINVAL;
+          printf("lo_client: Received outbuf does not match sent outbuf\n");
+          goto errout_with_socket;
+        }
+
+      printf("lo_client: Sleeping\n");
+      sleep(8);
+    }
+
+  close(sockfd);
+  return 0;
+
+errout_with_socket:
+  close(sockfd);
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: netloop_main
+ ****************************************************************************/
+
+#ifdef CONFIG_BUILD_KERNEL
+int main(int argc, FAR char *argv[])
+#else
+int netloop_main(int argc, char *argv[])
+#endif
+{
+  pthread_t tid;
+  int ret;
+
+  /* Start the listeners */
+
+  printf("netloop_main: Starting lo_listener thread\n");
+
+  ret = pthread_create(&tid, NULL, lo_listener, NULL);
+  if (ret != 0)
+    {
+      printf("netloop_main: Failed to create lo_listener thread: %d\n", ret);
+    }
+
+  /* Run the client */
+
+  ret = lo_client();
+  return 0;
+}

examples/netloop/netloop.h

@@ -0,0 +1,99 @@
+/****************************************************************************
+ * examples/netloop/netloop.h
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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
+ * COPYRIGHT OWNER OR CONTRIBUTORS 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.
+ *
+ ****************************************************************************/
+
+#ifndef __APPS_EXAMPLES_NETLOOP_NETLOOP_H
+#define __APPS_EXAMPLES_NETLOOP_NETLOOP_H
+
+/****************************************************************************
+ * Compilation Switches
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <pthread.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifdef CONFIG_DISABLE_POLL
+#  error "The polling API is disabled"
+#endif
+
+/* Here are all of the configuration settings that must be met to have TCP/IP
+ * poll/select support.  This kind of looks like overkill.
+ *
+ * CONFIG_NET                  - Network support must be enabled
+ * CONFIG_NSOCKET_DESCRIPTORS  - Socket descriptors must be allocated
+ * CONFIG_NET_TCP              - Only support on TCP (because read-ahead
+ *                               buffering s not yet support for UDP)
+ * CONFIG_NET_TCP_READAHEAD    - TCP/IP read-ahead buffering must be enabled
+ */
+
+
+#if !defined(CONFIG_NET) || CONFIG_NSOCKET_DESCRIPTORS <= 0
+#  error Network socket support not enabled
+#endif
+
+#if !defined(CONFIG_NET_TCP) && !defined(CONFIG_NET_TCP_READAHEAD) || \
+    !defined(CONFIG_NET_TCPBACKLOG) || !defined(CONFIG_NET_TCP_WRITE_BUFFERS)
+#  error TCP not configured correctly
+#endif
+
+#if !defined(CONFIG_NET_IPv4)
+#  error This test only works with IPv4
+#endif
+
+#define LISTENER_DELAY    3      /* 3 seconds */
+#define LISTENER_PORT     5471
+#define LO_ADDRESS        0x7f000001
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+void *lo_listener(pthread_addr_t pvarg);
+
+#endif /* __APPS_EXAMPLES_NETLOOP_NETLOOP_H */