src/vppinfra/socket.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2015 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 /*
   Copyright (c) 2001, 2002, 2003, 2005 Eliot Dresselhaus

   Permission is hereby granted, free of charge, to any person obtaining
   a copy of this software and associated documentation files (the
   "Software"), to deal in the Software without restriction, including
   without limitation the rights to use, copy, modify, merge, publish,
   distribute, sublicense, and/or sell copies of the Software, and to
   permit persons to whom the Software is furnished to do so, subject to
   the following conditions:

   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

 #include <stdio.h>
 #include <string.h>		/* strchr */
 #define __USE_GNU
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <sys/stat.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <unistd.h>
 #include <fcntl.h>

 #include <vppinfra/mem.h>
 #include <vppinfra/vec.h>
 #include <vppinfra/socket.h>
 #include <vppinfra/format.h>
 #include <vppinfra/error.h>

 void
 clib_socket_tx_add_formatted (clib_socket_t * s, char *fmt, ...)
 {
   va_list va;
   va_start (va, fmt);
   clib_socket_tx_add_va_formatted (s, fmt, &va);
   va_end (va);
 }

 /* Return and bind to an unused port. */
 static word
 find_free_port (word sock)
 {
   word port;

   for (port = IPPORT_USERRESERVED; port < 1 << 16; port++)
     {
       struct sockaddr_in a;

       memset (&a, 0, sizeof (a));	/* Warnings be gone */

       a.sin_family = PF_INET;
       a.sin_addr.s_addr = INADDR_ANY;
       a.sin_port = htons (port);

       if (bind (sock, (struct sockaddr *) &a, sizeof (a)) >= 0)
 	break;
     }

   return port < 1 << 16 ? port : -1;
 }

 /* Convert a config string to a struct sockaddr and length for use
    with bind or connect. */
 static clib_error_t *
 socket_config (char *config,
 	       void *addr, socklen_t * addr_len, u32 ip4_default_address)
 {
   clib_error_t *error = 0;

   if (!config)
     config = "";

   /* Anything that begins with a / is a local PF_LOCAL socket. */
   if (config[0] == '/')
     {
       struct sockaddr_un *su = addr;
       su->sun_family = PF_LOCAL;
       clib_memcpy (&su->sun_path, config,
 		   clib_min (sizeof (su->sun_path), 1 + strlen (config)));
       *addr_len = sizeof (su[0]);
     }

   /* Hostname or hostname:port or port. */
   else
     {
       char *host_name;
       int port = -1;
       struct sockaddr_in *sa = addr;

       host_name = 0;
       port = -1;
       if (config[0] != 0)
 	{
 	  unformat_input_t i;

 	  unformat_init_string (&i, config, strlen (config));
 	  if (unformat (&i, "%s:%d", &host_name, &port)
 	      || unformat (&i, "%s:0x%x", &host_name, &port))
 	    ;
 	  else if (unformat (&i, "%s", &host_name))
 	    ;
 	  else
 	    error = clib_error_return (0, "unknown input `%U'",
 				       format_unformat_error, &i);
 	  unformat_free (&i);

 	  if (error)
 	    goto done;
 	}

       sa->sin_family = PF_INET;
       *addr_len = sizeof (sa[0]);
       if (port != -1)
 	sa->sin_port = htons (port);
       else
 	sa->sin_port = 0;

       if (host_name)
 	{
 	  struct in_addr host_addr;

 	  /* Recognize localhost to avoid host lookup in most common cast. */
 	  if (!strcmp (host_name, "localhost"))
 	    sa->sin_addr.s_addr = htonl (INADDR_LOOPBACK);

 	  else if (inet_aton (host_name, &host_addr))
 	    sa->sin_addr = host_addr;

 	  else if (host_name && strlen (host_name) > 0)
 	    {
 	      struct hostent *host = gethostbyname (host_name);
 	      if (!host)
 		error = clib_error_return (0, "unknown host `%s'", config);
 	      else
 		clib_memcpy (&sa->sin_addr.s_addr, host->h_addr_list[0],
 			     host->h_length);
 	    }

 	  else
 	    sa->sin_addr.s_addr = htonl (ip4_default_address);

 	  vec_free (host_name);
 	  if (error)
 	    goto done;
 	}
     }

 done:
   return error;
 }

 static clib_error_t *
 default_socket_write (clib_socket_t * s)
 {
   clib_error_t *err = 0;
   word written = 0;
   word fd = 0;
   word tx_len;

   fd = s->fd;

   /* Map standard input to standard output.
      Typically, fd is a socket for which read/write both work. */
   if (fd == 0)
     fd = 1;

   tx_len = vec_len (s->tx_buffer);
   written = write (fd, s->tx_buffer, tx_len);

   /* Ignore certain errors. */
   if (written < 0 && !unix_error_is_fatal (errno))
     written = 0;

   /* A "real" error occurred. */
   if (written < 0)
     {
       err = clib_error_return_unix (0, "write %wd bytes (fd %d, '%s')",
 				    tx_len, s->fd, s->config);
       vec_free (s->tx_buffer);
       goto done;
     }

   /* Reclaim the transmitted part of the tx buffer on successful writes. */
   else if (written > 0)
     {
       if (written == tx_len)
 	_vec_len (s->tx_buffer) = 0;
       else
 	vec_delete (s->tx_buffer, written, 0);
     }

   /* If a non-fatal error occurred AND
      the buffer is full, then we must free it. */
   else if (written == 0 && tx_len > 64 * 1024)
     {
       vec_free (s->tx_buffer);
     }

 done:
   return err;
 }

 static clib_error_t *
 default_socket_read (clib_socket_t * sock, int n_bytes)
 {
   word fd, n_read;
   u8 *buf;

   /* RX side of socket is down once end of file is reached. */
   if (sock->flags & CLIB_SOCKET_F_RX_END_OF_FILE)
     return 0;

   fd = sock->fd;

   n_bytes = clib_max (n_bytes, 4096);
   vec_add2 (sock->rx_buffer, buf, n_bytes);

   if ((n_read = read (fd, buf, n_bytes)) < 0)
     {
       n_read = 0;

       /* Ignore certain errors. */
       if (!unix_error_is_fatal (errno))
 	goto non_fatal;

       return clib_error_return_unix (0, "read %d bytes (fd %d, '%s')",
 				     n_bytes, sock->fd, sock->config);
     }

   /* Other side closed the socket. */
   if (n_read == 0)
     sock->flags |= CLIB_SOCKET_F_RX_END_OF_FILE;

 non_fatal:
   _vec_len (sock->rx_buffer) += n_read - n_bytes;

   return 0;
 }

 static clib_error_t *
 default_socket_close (clib_socket_t * s)
 {
   if (close (s->fd) < 0)
     return clib_error_return_unix (0, "close (fd %d, %s)", s->fd, s->config);
   return 0;
 }

 static clib_error_t *
 default_socket_sendmsg (clib_socket_t * s, void *msg, int msglen,
 			int fds[], int num_fds)
 {
   struct msghdr mh = { 0 };
   struct iovec iov[1];
   char ctl[CMSG_SPACE (sizeof (int)) * num_fds];
   int rv;

   iov[0].iov_base = msg;
   iov[0].iov_len = msglen;
   mh.msg_iov = iov;
   mh.msg_iovlen = 1;

   if (num_fds > 0)
     {
       struct cmsghdr *cmsg;
       memset (&ctl, 0, sizeof (ctl));
       mh.msg_control = ctl;
       mh.msg_controllen = sizeof (ctl);
       cmsg = CMSG_FIRSTHDR (&mh);
       cmsg->cmsg_len = CMSG_LEN (sizeof (int) * num_fds);
       cmsg->cmsg_level = SOL_SOCKET;
       cmsg->cmsg_type = SCM_RIGHTS;
       memcpy (CMSG_DATA (cmsg), fds, sizeof (int) * num_fds);
     }
   rv = sendmsg (s->fd, &mh, 0);
   if (rv < 0)
     return clib_error_return_unix (0, "sendmsg");
   return 0;
 }


 static clib_error_t *
 default_socket_recvmsg (clib_socket_t * s, void *msg, int msglen,
 			int fds[], int num_fds)
 {
   char ctl[CMSG_SPACE (sizeof (int) * num_fds) +
 	   CMSG_SPACE (sizeof (struct ucred))];
   struct msghdr mh = { 0 };
   struct iovec iov[1];
   ssize_t size;
   struct ucred *cr = 0;
   struct cmsghdr *cmsg;

   iov[0].iov_base = msg;
   iov[0].iov_len = msglen;
   mh.msg_iov = iov;
   mh.msg_iovlen = 1;
   mh.msg_control = ctl;
   mh.msg_controllen = sizeof (ctl);

   memset (ctl, 0, sizeof (ctl));

   /* receive the incoming message */
   size = recvmsg (s->fd, &mh, 0);
   if (size != msglen)
     {
       return (size == 0) ? clib_error_return (0, "disconnected") :
 	clib_error_return_unix (0, "recvmsg: malformed message (fd %d, '%s')",
 				s->fd, s->config);
     }

   cmsg = CMSG_FIRSTHDR (&mh);
   while (cmsg)
     {
       if (cmsg->cmsg_level == SOL_SOCKET)
 	{
 	  if (cmsg->cmsg_type == SCM_CREDENTIALS)
 	    {
 	      cr = (struct ucred *) CMSG_DATA (cmsg);
 	      s->uid = cr->uid;
 	      s->gid = cr->gid;
 	      s->pid = cr->pid;
 	    }
 	  else if (cmsg->cmsg_type == SCM_RIGHTS)
 	    {
 	      clib_memcpy (fds, CMSG_DATA (cmsg), num_fds * sizeof (int));
 	    }
 	}
       cmsg = CMSG_NXTHDR (&mh, cmsg);
     }
   return 0;
 }

 static void
 socket_init_funcs (clib_socket_t * s)
 {
   if (!s->write_func)
     s->write_func = default_socket_write;
   if (!s->read_func)
     s->read_func = default_socket_read;
   if (!s->close_func)
     s->close_func = default_socket_close;
   if (!s->sendmsg_func)
     s->sendmsg_func = default_socket_sendmsg;
   if (!s->recvmsg_func)
     s->recvmsg_func = default_socket_recvmsg;
 }

 clib_error_t *
 clib_socket_init (clib_socket_t * s)
 {
   union
   {
     struct sockaddr sa;
     struct sockaddr_un su;
   } addr;
   socklen_t addr_len = 0;
   int socket_type;
   clib_error_t *error = 0;
   word port;

   error = socket_config (s->config, &addr.sa, &addr_len,
 			 (s->flags & CLIB_SOCKET_F_IS_SERVER
 			  ? INADDR_LOOPBACK : INADDR_ANY));
   if (error)
     goto done;

   socket_init_funcs (s);

   socket_type = s->flags & CLIB_SOCKET_F_SEQPACKET ?
     SOCK_SEQPACKET : SOCK_STREAM;

   s->fd = socket (addr.sa.sa_family, socket_type, 0);
   if (s->fd < 0)
     {
       error = clib_error_return_unix (0, "socket (fd %d, '%s')",
 				      s->fd, s->config);
       goto done;
     }

   port = 0;
   if (addr.sa.sa_family == PF_INET)
     port = ((struct sockaddr_in *) &addr)->sin_port;

   if (s->flags & CLIB_SOCKET_F_IS_SERVER)
     {
       uword need_bind = 1;

       if (addr.sa.sa_family == PF_INET)
 	{
 	  if (port == 0)
 	    {
 	      port = find_free_port (s->fd);
 	      if (port < 0)
 		{
 		  error = clib_error_return (0, "no free port (fd %d, '%s')",
 					     s->fd, s->config);
 		  goto done;
 		}
 	      need_bind = 0;
 	    }
 	}
       if (addr.sa.sa_family == PF_LOCAL)
 	unlink (((struct sockaddr_un *) &addr)->sun_path);

       /* Make address available for multiple users. */
       {
 	int v = 1;
 	if (setsockopt (s->fd, SOL_SOCKET, SO_REUSEADDR, &v, sizeof (v)) < 0)
 	  clib_unix_warning ("setsockopt SO_REUSEADDR fails");
       }

       if (addr.sa.sa_family == PF_LOCAL && s->flags & CLIB_SOCKET_F_PASSCRED)
 	{
 	  int x = 1;
 	  if (setsockopt (s->fd, SOL_SOCKET, SO_PASSCRED, &x, sizeof (x)) < 0)
 	    {
 	      error = clib_error_return_unix (0, "setsockopt (SO_PASSCRED, "
 					      "fd %d, '%s')", s->fd,
 					      s->config);
 	      goto done;
 	    }
 	}

       if (need_bind && bind (s->fd, &addr.sa, addr_len) < 0)
 	{
 	  error = clib_error_return_unix (0, "bind (fd %d, '%s')",
 					  s->fd, s->config);
 	  goto done;
 	}

       if (listen (s->fd, 5) < 0)
 	{
 	  error = clib_error_return_unix (0, "listen (fd %d, '%s')",
 					  s->fd, s->config);
 	  goto done;
 	}
       if (addr.sa.sa_family == PF_LOCAL
 	  && s->flags & CLIB_SOCKET_F_ALLOW_GROUP_WRITE)
 	{
 	  struct stat st = { 0 };
 	  if (stat (((struct sockaddr_un *) &addr)->sun_path, &st) < 0)
 	    {
 	      error = clib_error_return_unix (0, "stat (fd %d, '%s')",
 					      s->fd, s->config);
 	      goto done;
 	    }
 	  st.st_mode |= S_IWGRP;
 	  if (chmod (((struct sockaddr_un *) &addr)->sun_path, st.st_mode) <
 	      0)
 	    {
 	      error =
 		clib_error_return_unix (0, "chmod (fd %d, '%s', mode %o)",
 					s->fd, s->config, st.st_mode);
 	      goto done;
 	    }
 	}
     }
   else
     {
       if ((s->flags & CLIB_SOCKET_F_NON_BLOCKING_CONNECT)
 	  && fcntl (s->fd, F_SETFL, O_NONBLOCK) < 0)
 	{
 	  error = clib_error_return_unix (0, "fcntl NONBLOCK (fd %d, '%s')",
 					  s->fd, s->config);
 	  goto done;
 	}

       if (connect (s->fd, &addr.sa, addr_len) < 0
 	  && !((s->flags & CLIB_SOCKET_F_NON_BLOCKING_CONNECT) &&
 	       errno == EINPROGRESS))
 	{
 	  error = clib_error_return_unix (0, "connect (fd %d, '%s')",
 					  s->fd, s->config);
 	  goto done;
 	}
     }

   return error;

 done:
   if (s->fd > 0)
     close (s->fd);
   return error;
 }

 clib_error_t *
 clib_socket_accept (clib_socket_t * server, clib_socket_t * client)
 {
   clib_error_t *err = 0;
   socklen_t len = 0;

   memset (client, 0, sizeof (client[0]));

   /* Accept the new socket connection. */
   client->fd = accept (server->fd, 0, 0);
   if (client->fd < 0)
     return clib_error_return_unix (0, "accept (fd %d, '%s')",
 				   server->fd, server->config);

   /* Set the new socket to be non-blocking. */
   if (fcntl (client->fd, F_SETFL, O_NONBLOCK) < 0)
     {
       err = clib_error_return_unix (0, "fcntl O_NONBLOCK (fd %d)",
 				    client->fd);
       goto close_client;
     }

   /* Get peer info. */
   len = sizeof (client->peer);
   if (getpeername (client->fd, (struct sockaddr *) &client->peer, &len) < 0)
     {
       err = clib_error_return_unix (0, "getpeername (fd %d)", client->fd);
       goto close_client;
     }

   client->flags = CLIB_SOCKET_F_IS_CLIENT;

   socket_init_funcs (client);
   return 0;

 close_client:
   close (client->fd);
   return err;
 }

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2015 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	/*
	Copyright (c) 2001, 2002, 2003, 2005 Eliot Dresselhaus

	Permission is hereby granted, free of charge, to any person obtaining
	a copy of this software and associated documentation files (the
	"Software"), to deal in the Software without restriction, including
	without limitation the rights to use, copy, modify, merge, publish,
	distribute, sublicense, and/or sell copies of the Software, and to
	permit persons to whom the Software is furnished to do so, subject to
	the following conditions:

	The above copyright notice and this permission notice shall be
	included in all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/

	#include <stdio.h>
	#include <string.h> /* strchr */
	#define __USE_GNU
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <sys/un.h>
	#include <sys/stat.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <netdb.h>
	#include <unistd.h>
	#include <fcntl.h>

	#include <vppinfra/mem.h>
	#include <vppinfra/vec.h>
	#include <vppinfra/socket.h>
	#include <vppinfra/format.h>
	#include <vppinfra/error.h>

	void
	clib_socket_tx_add_formatted (clib_socket_t * s, char *fmt, ...)
	{
	va_list va;
	va_start (va, fmt);
	clib_socket_tx_add_va_formatted (s, fmt, &va);
	va_end (va);
	}

	/* Return and bind to an unused port. */
	static word
	find_free_port (word sock)
	{
	word port;

	for (port = IPPORT_USERRESERVED; port < 1 << 16; port++)
	{
	struct sockaddr_in a;

	memset (&a, 0, sizeof (a)); /* Warnings be gone */

	a.sin_family = PF_INET;
	a.sin_addr.s_addr = INADDR_ANY;
	a.sin_port = htons (port);

	if (bind (sock, (struct sockaddr *) &a, sizeof (a)) >= 0)
	break;
	}

	return port < 1 << 16 ? port : -1;
	}

	/* Convert a config string to a struct sockaddr and length for use
	with bind or connect. */
	static clib_error_t *
	socket_config (char *config,
	void addr, socklen_t addr_len, u32 ip4_default_address)
	{
	clib_error_t *error = 0;

	if (!config)
	config = "";

	/* Anything that begins with a / is a local PF_LOCAL socket. */
	if (config[0] == '/')
	{
	struct sockaddr_un *su = addr;
	su->sun_family = PF_LOCAL;
	clib_memcpy (&su->sun_path, config,
	clib_min (sizeof (su->sun_path), 1 + strlen (config)));
	*addr_len = sizeof (su[0]);
	}

	/* Hostname or hostname:port or port. */
	else
	{
	char *host_name;
	int port = -1;
	struct sockaddr_in *sa = addr;

	host_name = 0;
	port = -1;
	if (config[0] != 0)
	{
	unformat_input_t i;

	unformat_init_string (&i, config, strlen (config));
	if (unformat (&i, "%s:%d", &host_name, &port)
	\|\| unformat (&i, "%s:0x%x", &host_name, &port))
	;
	else if (unformat (&i, "%s", &host_name))
	;
	else
	error = clib_error_return (0, "unknown input `%U'",
	format_unformat_error, &i);
	unformat_free (&i);

	if (error)
	goto done;
	}

	sa->sin_family = PF_INET;
	*addr_len = sizeof (sa[0]);
	if (port != -1)
	sa->sin_port = htons (port);
	else
	sa->sin_port = 0;

	if (host_name)
	{
	struct in_addr host_addr;

	/* Recognize localhost to avoid host lookup in most common cast. */
	if (!strcmp (host_name, "localhost"))
	sa->sin_addr.s_addr = htonl (INADDR_LOOPBACK);

	else if (inet_aton (host_name, &host_addr))
	sa->sin_addr = host_addr;

	else if (host_name && strlen (host_name) > 0)
	{
	struct hostent *host = gethostbyname (host_name);
	if (!host)
	error = clib_error_return (0, "unknown host `%s'", config);
	else
	clib_memcpy (&sa->sin_addr.s_addr, host->h_addr_list[0],
	host->h_length);
	}

	else
	sa->sin_addr.s_addr = htonl (ip4_default_address);

	vec_free (host_name);
	if (error)
	goto done;
	}
	}

	done:
	return error;
	}

	static clib_error_t *
	default_socket_write (clib_socket_t * s)
	{
	clib_error_t *err = 0;
	word written = 0;
	word fd = 0;
	word tx_len;

	fd = s->fd;

	/* Map standard input to standard output.
	Typically, fd is a socket for which read/write both work. */
	if (fd == 0)
	fd = 1;

	tx_len = vec_len (s->tx_buffer);
	written = write (fd, s->tx_buffer, tx_len);

	/* Ignore certain errors. */
	if (written < 0 && !unix_error_is_fatal (errno))
	written = 0;

	/* A "real" error occurred. */
	if (written < 0)
	{
	err = clib_error_return_unix (0, "write %wd bytes (fd %d, '%s')",
	tx_len, s->fd, s->config);
	vec_free (s->tx_buffer);
	goto done;
	}

	/* Reclaim the transmitted part of the tx buffer on successful writes. */
	else if (written > 0)
	{
	if (written == tx_len)
	_vec_len (s->tx_buffer) = 0;
	else
	vec_delete (s->tx_buffer, written, 0);
	}

	/* If a non-fatal error occurred AND
	the buffer is full, then we must free it. */
	else if (written == 0 && tx_len > 64 * 1024)
	{
	vec_free (s->tx_buffer);
	}

	done:
	return err;
	}

	static clib_error_t *
	default_socket_read (clib_socket_t * sock, int n_bytes)
	{
	word fd, n_read;
	u8 *buf;

	/* RX side of socket is down once end of file is reached. */
	if (sock->flags & CLIB_SOCKET_F_RX_END_OF_FILE)
	return 0;

	fd = sock->fd;

	n_bytes = clib_max (n_bytes, 4096);
	vec_add2 (sock->rx_buffer, buf, n_bytes);

	if ((n_read = read (fd, buf, n_bytes)) < 0)
	{
	n_read = 0;

	/* Ignore certain errors. */
	if (!unix_error_is_fatal (errno))
	goto non_fatal;

	return clib_error_return_unix (0, "read %d bytes (fd %d, '%s')",
	n_bytes, sock->fd, sock->config);
	}

	/* Other side closed the socket. */
	if (n_read == 0)
	sock->flags \|= CLIB_SOCKET_F_RX_END_OF_FILE;

	non_fatal:
	_vec_len (sock->rx_buffer) += n_read - n_bytes;

	return 0;
	}

	static clib_error_t *
	default_socket_close (clib_socket_t * s)
	{
	if (close (s->fd) < 0)
	return clib_error_return_unix (0, "close (fd %d, %s)", s->fd, s->config);
	return 0;
	}

	static clib_error_t *
	default_socket_sendmsg (clib_socket_t * s, void *msg, int msglen,
	int fds[], int num_fds)
	{
	struct msghdr mh = { 0 };
	struct iovec iov[1];
	char ctl[CMSG_SPACE (sizeof (int)) * num_fds];
	int rv;

	iov[0].iov_base = msg;
	iov[0].iov_len = msglen;
	mh.msg_iov = iov;
	mh.msg_iovlen = 1;

	if (num_fds > 0)
	{
	struct cmsghdr *cmsg;
	memset (&ctl, 0, sizeof (ctl));
	mh.msg_control = ctl;
	mh.msg_controllen = sizeof (ctl);
	cmsg = CMSG_FIRSTHDR (&mh);
	cmsg->cmsg_len = CMSG_LEN (sizeof (int) * num_fds);
	cmsg->cmsg_level = SOL_SOCKET;
	cmsg->cmsg_type = SCM_RIGHTS;
	memcpy (CMSG_DATA (cmsg), fds, sizeof (int) * num_fds);
	}
	rv = sendmsg (s->fd, &mh, 0);
	if (rv < 0)
	return clib_error_return_unix (0, "sendmsg");
	return 0;
	}


	static clib_error_t *
	default_socket_recvmsg (clib_socket_t * s, void *msg, int msglen,
	int fds[], int num_fds)
	{
	char ctl[CMSG_SPACE (sizeof (int) * num_fds) +
	CMSG_SPACE (sizeof (struct ucred))];
	struct msghdr mh = { 0 };
	struct iovec iov[1];
	ssize_t size;
	struct ucred *cr = 0;
	struct cmsghdr *cmsg;

	iov[0].iov_base = msg;
	iov[0].iov_len = msglen;
	mh.msg_iov = iov;
	mh.msg_iovlen = 1;
	mh.msg_control = ctl;
	mh.msg_controllen = sizeof (ctl);

	memset (ctl, 0, sizeof (ctl));

	/* receive the incoming message */
	size = recvmsg (s->fd, &mh, 0);
	if (size != msglen)
	{
	return (size == 0) ? clib_error_return (0, "disconnected") :
	clib_error_return_unix (0, "recvmsg: malformed message (fd %d, '%s')",
	s->fd, s->config);
	}

	cmsg = CMSG_FIRSTHDR (&mh);
	while (cmsg)
	{
	if (cmsg->cmsg_level == SOL_SOCKET)
	{
	if (cmsg->cmsg_type == SCM_CREDENTIALS)
	{
	cr = (struct ucred *) CMSG_DATA (cmsg);
	s->uid = cr->uid;
	s->gid = cr->gid;
	s->pid = cr->pid;
	}
	else if (cmsg->cmsg_type == SCM_RIGHTS)
	{
	clib_memcpy (fds, CMSG_DATA (cmsg), num_fds * sizeof (int));
	}
	}
	cmsg = CMSG_NXTHDR (&mh, cmsg);
	}
	return 0;
	}

	static void
	socket_init_funcs (clib_socket_t * s)
	{
	if (!s->write_func)
	s->write_func = default_socket_write;
	if (!s->read_func)
	s->read_func = default_socket_read;
	if (!s->close_func)
	s->close_func = default_socket_close;
	if (!s->sendmsg_func)
	s->sendmsg_func = default_socket_sendmsg;
	if (!s->recvmsg_func)
	s->recvmsg_func = default_socket_recvmsg;
	}

	clib_error_t *
	clib_socket_init (clib_socket_t * s)
	{
	union
	{
	struct sockaddr sa;
	struct sockaddr_un su;
	} addr;
	socklen_t addr_len = 0;
	int socket_type;
	clib_error_t *error = 0;
	word port;

	error = socket_config (s->config, &addr.sa, &addr_len,
	(s->flags & CLIB_SOCKET_F_IS_SERVER
	? INADDR_LOOPBACK : INADDR_ANY));
	if (error)
	goto done;

	socket_init_funcs (s);

	socket_type = s->flags & CLIB_SOCKET_F_SEQPACKET ?
	SOCK_SEQPACKET : SOCK_STREAM;

	s->fd = socket (addr.sa.sa_family, socket_type, 0);
	if (s->fd < 0)
	{
	error = clib_error_return_unix (0, "socket (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}

	port = 0;
	if (addr.sa.sa_family == PF_INET)
	port = ((struct sockaddr_in *) &addr)->sin_port;

	if (s->flags & CLIB_SOCKET_F_IS_SERVER)
	{
	uword need_bind = 1;

	if (addr.sa.sa_family == PF_INET)
	{
	if (port == 0)
	{
	port = find_free_port (s->fd);
	if (port < 0)
	{
	error = clib_error_return (0, "no free port (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}
	need_bind = 0;
	}
	}
	if (addr.sa.sa_family == PF_LOCAL)
	unlink (((struct sockaddr_un *) &addr)->sun_path);

	/* Make address available for multiple users. */
	{
	int v = 1;
	if (setsockopt (s->fd, SOL_SOCKET, SO_REUSEADDR, &v, sizeof (v)) < 0)
	clib_unix_warning ("setsockopt SO_REUSEADDR fails");
	}

	if (addr.sa.sa_family == PF_LOCAL && s->flags & CLIB_SOCKET_F_PASSCRED)
	{
	int x = 1;
	if (setsockopt (s->fd, SOL_SOCKET, SO_PASSCRED, &x, sizeof (x)) < 0)
	{
	error = clib_error_return_unix (0, "setsockopt (SO_PASSCRED, "
	"fd %d, '%s')", s->fd,
	s->config);
	goto done;
	}
	}

	if (need_bind && bind (s->fd, &addr.sa, addr_len) < 0)
	{
	error = clib_error_return_unix (0, "bind (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}

	if (listen (s->fd, 5) < 0)
	{
	error = clib_error_return_unix (0, "listen (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}
	if (addr.sa.sa_family == PF_LOCAL
	&& s->flags & CLIB_SOCKET_F_ALLOW_GROUP_WRITE)
	{
	struct stat st = { 0 };
	if (stat (((struct sockaddr_un *) &addr)->sun_path, &st) < 0)
	{
	error = clib_error_return_unix (0, "stat (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}
	st.st_mode \|= S_IWGRP;
	if (chmod (((struct sockaddr_un *) &addr)->sun_path, st.st_mode) <
	0)
	{
	error =
	clib_error_return_unix (0, "chmod (fd %d, '%s', mode %o)",
	s->fd, s->config, st.st_mode);
	goto done;
	}
	}
	}
	else
	{
	if ((s->flags & CLIB_SOCKET_F_NON_BLOCKING_CONNECT)
	&& fcntl (s->fd, F_SETFL, O_NONBLOCK) < 0)
	{
	error = clib_error_return_unix (0, "fcntl NONBLOCK (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}

	if (connect (s->fd, &addr.sa, addr_len) < 0
	&& !((s->flags & CLIB_SOCKET_F_NON_BLOCKING_CONNECT) &&
	errno == EINPROGRESS))
	{
	error = clib_error_return_unix (0, "connect (fd %d, '%s')",
	s->fd, s->config);
	goto done;
	}
	}

	return error;

	done:
	if (s->fd > 0)
	close (s->fd);
	return error;
	}

	clib_error_t *
	clib_socket_accept (clib_socket_t * server, clib_socket_t * client)
	{
	clib_error_t *err = 0;
	socklen_t len = 0;

	memset (client, 0, sizeof (client[0]));

	/* Accept the new socket connection. */
	client->fd = accept (server->fd, 0, 0);
	if (client->fd < 0)
	return clib_error_return_unix (0, "accept (fd %d, '%s')",
	server->fd, server->config);

	/* Set the new socket to be non-blocking. */
	if (fcntl (client->fd, F_SETFL, O_NONBLOCK) < 0)
	{
	err = clib_error_return_unix (0, "fcntl O_NONBLOCK (fd %d)",
	client->fd);
	goto close_client;
	}

	/* Get peer info. */
	len = sizeof (client->peer);
	if (getpeername (client->fd, (struct sockaddr *) &client->peer, &len) < 0)
	{
	err = clib_error_return_unix (0, "getpeername (fd %d)", client->fd);
	goto close_client;
	}

	client->flags = CLIB_SOCKET_F_IS_CLIENT;

	socket_init_funcs (client);
	return 0;

	close_client:
	close (client->fd);
	return err;
	}

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/