newlib/winsup/cygwin/fhandler_socket_inet.cc

/* fhandler_socket_inet.cc.

   See fhandler.h for a description of the fhandler classes.

   This file is part of Cygwin.

   This software is a copyrighted work licensed under the terms of the
   Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
   details. */

#define  __INSIDE_CYGWIN_NET__
#define USE_SYS_TYPES_FD_SET

#include "winsup.h"
#ifdef __x86_64__
/* 2014-04-24: Current Mingw headers define sockaddr_in6 using u_long (8 byte)
   because a redefinition for LP64 systems is missing.  This leads to a wrong
   definition and size of sockaddr_in6 when building with winsock headers.
   This definition is also required to use the right u_long type in subsequent
   function calls. */
#undef u_long
#define u_long __ms_u_long
#endif
#include <ntsecapi.h>
#include <ws2tcpip.h>
#include <mswsock.h>
#include <iphlpapi.h>
#include "cygerrno.h"
#include "security.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include <asm/byteorder.h>
#include "cygwin/version.h"
#include "perprocess.h"
#include "shared_info.h"
#include "sigproc.h"
#include "wininfo.h"
#include <unistd.h>
#include <sys/param.h>
#include <sys/statvfs.h>
#include <cygwin/acl.h>
#include "cygtls.h"
#include <sys/un.h>
#include "ntdll.h"
#include "miscfuncs.h"
#include "tls_pbuf.h"

#define ASYNC_MASK (FD_READ|FD_WRITE|FD_OOB|FD_ACCEPT|FD_CONNECT)
#define EVENT_MASK (FD_READ|FD_WRITE|FD_OOB|FD_ACCEPT|FD_CONNECT|FD_CLOSE)

#define LOCK_EVENTS	\
  if (wsock_mtx && \
      WaitForSingleObject (wsock_mtx, INFINITE) != WAIT_FAILED) \
    {

#define UNLOCK_EVENTS \
      ReleaseMutex (wsock_mtx); \
    }

/* cygwin internal: map sockaddr into internet domain address */
static int
get_inet_addr_inet (const struct sockaddr *in, int inlen,
		    struct sockaddr_storage *out, int *outlen)
{
  switch (in->sa_family)
    {
    case AF_INET:
      memcpy (out, in, inlen);
      *outlen = inlen;
      /* If the peer address given in connect or sendto is the ANY address,
	 Winsock fails with WSAEADDRNOTAVAIL, while Linux converts that into
	 a connection/send attempt to LOOPBACK.  We're doing the same here. */
      if (((struct sockaddr_in *) out)->sin_addr.s_addr == htonl (INADDR_ANY))
	((struct sockaddr_in *) out)->sin_addr.s_addr = htonl (INADDR_LOOPBACK);
      return 0;
    case AF_INET6:
      memcpy (out, in, inlen);
      *outlen = inlen;
      /* See comment in AF_INET case. */
      if (IN6_IS_ADDR_UNSPECIFIED (&((struct sockaddr_in6 *) out)->sin6_addr))
	((struct sockaddr_in6 *) out)->sin6_addr = in6addr_loopback;
      return 0;
    default:
      set_errno (EAFNOSUPPORT);
      return SOCKET_ERROR;
    }
}

static int
convert_ws1_ip_optname (int optname)
{
  static int ws2_optname[] =
  {
    0,
    IP_OPTIONS,
    IP_MULTICAST_IF,
    IP_MULTICAST_TTL,
    IP_MULTICAST_LOOP,
    IP_ADD_MEMBERSHIP,
    IP_DROP_MEMBERSHIP,
    IP_TTL,
    IP_TOS,
    IP_DONTFRAGMENT
  };
  return (optname < 1 || optname > _WS1_IP_DONTFRAGMENT)
	 ? optname
	 : ws2_optname[optname];
}

fhandler_socket_inet::fhandler_socket_inet () :
  fhandler_socket ()
{
}

fhandler_socket_inet::~fhandler_socket_inet ()
{
}

int
fhandler_socket_inet::socket (int af, int type, int protocol, int flags)
{
  SOCKET sock;
  int ret;

  sock = ::socket (af, type, protocol);
  if (sock == INVALID_SOCKET)
    {
      set_winsock_errno ();
      return -1;
    }
  ret = set_socket_handle (sock, af, type, flags);
  if (ret < 0)
    ::closesocket (sock);
  return ret;
}

int
fhandler_socket_inet::bind (const struct sockaddr *name, int namelen)
{
  int res = -1;

  if (!saw_reuseaddr ())
    {
      /* If the application didn't explicitely request SO_REUSEADDR,
	 enforce POSIX standard socket binding behaviour by setting the
	 SO_EXCLUSIVEADDRUSE socket option.  See cygwin_setsockopt()
	 for a more detailed description. */
      int on = 1;
      int ret = ::setsockopt (get_socket (), SOL_SOCKET,
			      SO_EXCLUSIVEADDRUSE,
			      (const char *) &on, sizeof on);
      debug_printf ("%d = setsockopt(SO_EXCLUSIVEADDRUSE), %E", ret);
    }
  if (::bind (get_socket (), name, namelen))
    set_winsock_errno ();
  else
    res = 0;

  return res;
}

int
fhandler_socket_inet::connect (const struct sockaddr *name, int namelen)
{
  struct sockaddr_storage sst;

  if (get_inet_addr_inet (name, namelen, &sst, &namelen) == SOCKET_ERROR)
    return SOCKET_ERROR;

  /* Initialize connect state to "connect_pending".  State is ultimately set
     to "connected" or "connect_failed" in wait_for_events when the FD_CONNECT
     event occurs.  Note that the underlying OS sockets are always non-blocking
     and a successfully initiated non-blocking Winsock connect always returns
     WSAEWOULDBLOCK.  Thus it's safe to rely on event handling.

     Check for either unconnected or connect_failed since in both cases it's
     allowed to retry connecting the socket.  It's also ok (albeit ugly) to
     call connect to check if a previous non-blocking connect finished.

     Set connect_state before calling connect, otherwise a race condition with
     an already running select or poll might occur. */
  if (connect_state () == unconnected || connect_state () == connect_failed)
    connect_state (connect_pending);

  int res = ::connect (get_socket (), (struct sockaddr *) &sst, namelen);
  if (!is_nonblocking ()
      && res == SOCKET_ERROR
      && WSAGetLastError () == WSAEWOULDBLOCK)
    res = wait_for_events (FD_CONNECT | FD_CLOSE, 0);

  if (res)
    {
      DWORD err = WSAGetLastError ();

      /* Some applications use the ugly technique to check if a non-blocking
         connect succeeded by calling connect again, until it returns EISCONN.
	 This circumvents the event handling and connect_state is never set.
	 Thus we check for this situation here. */
      if (err == WSAEISCONN)
	connect_state (connected);
      /* Winsock returns WSAEWOULDBLOCK if the non-blocking socket cannot be
         conected immediately.  Convert to POSIX/Linux compliant EINPROGRESS. */
      else if (is_nonblocking () && err == WSAEWOULDBLOCK)
	WSASetLastError (WSAEINPROGRESS);
      /* Winsock returns WSAEINVAL if the socket is already a listener.
	 Convert to POSIX/Linux compliant EISCONN. */
      else if (err == WSAEINVAL && connect_state () == listener)
	WSASetLastError (WSAEISCONN);
      /* Any other error except WSAEALREADY during connect_pending means the
         connect failed. */
      else if (connect_state () == connect_pending && err != WSAEALREADY)
	connect_state (connect_failed);
      set_winsock_errno ();
    }

  return res;
}

int
fhandler_socket_inet::listen (int backlog)
{
  int res = ::listen (get_socket (), backlog);
  if (res && WSAGetLastError () == WSAEINVAL)
    {
      /* It's perfectly valid to call listen on an unbound INET socket.
	 In this case the socket is automatically bound to an unused
	 port number, listening on all interfaces.  On WinSock, listen
	 fails with WSAEINVAL when it's called on an unbound socket.
	 So we have to bind manually here to have POSIX semantics. */
      if (get_addr_family () == AF_INET)
	{
	  struct sockaddr_in sin;
	  sin.sin_family = AF_INET;
	  sin.sin_port = 0;
	  sin.sin_addr.s_addr = INADDR_ANY;
	  if (!::bind (get_socket (), (struct sockaddr *) &sin, sizeof sin))
	    res = ::listen (get_socket (), backlog);
	}
      else if (get_addr_family () == AF_INET6)
	{
	  struct sockaddr_in6 sin6;
	  memset (&sin6, 0, sizeof sin6);
	  sin6.sin6_family = AF_INET6;
	  if (!::bind (get_socket (), (struct sockaddr *) &sin6, sizeof sin6))
	    res = ::listen (get_socket (), backlog);
	}
    }
  if (!res)
    connect_state (listener);	/* gets set to connected on accepted socket. */
  else
    set_winsock_errno ();
  return res;
}

int
fhandler_socket_inet::accept4 (struct sockaddr *peer, int *len, int flags)
{
  int ret = -1;
  /* Allows NULL peer and len parameters. */
  struct sockaddr_storage lpeer;
  int llen = sizeof (struct sockaddr_storage);

  /* Windows event handling does not check for the validity of the desired
     flags so we have to do it here. */
  if (connect_state () != listener)
    {
      WSASetLastError (WSAEINVAL);
      set_winsock_errno ();
      return -1;
    }

  SOCKET res = INVALID_SOCKET;
  while (!(res = wait_for_events (FD_ACCEPT | FD_CLOSE, 0))
	 && (res = ::accept (get_socket (), (struct sockaddr *) &lpeer, &llen))
	    == INVALID_SOCKET
	 && WSAGetLastError () == WSAEWOULDBLOCK)
    ;
  if (res == INVALID_SOCKET)
    set_winsock_errno ();
  else
    {
      cygheap_fdnew fd;

      if (fd >= 0)
	{
	  fhandler_socket_inet *sock = (fhandler_socket_inet *)
				       build_fh_dev (dev ());
	  if (sock && sock->set_socket_handle (res, get_addr_family (),
					       get_socket_type (),
					       get_socket_flags ()))
	    {
	      sock->async_io (false); /* set_socket_handle disables async. */
	      /* No locking necessary at this point. */
	      sock->wsock_events->events = wsock_events->events | FD_WRITE;
	      sock->wsock_events->owner = wsock_events->owner;
	      sock->connect_state (connected);
	      fd = sock;
	      if (fd <= 2)
		set_std_handle (fd);
	      ret = fd;
	      if (peer)
		{
		  memcpy (peer, &lpeer, MIN (*len, llen));
		  *len = llen;
		}
	    }
	}
      if (ret == -1)
	::closesocket (res);
    }
  return ret;
}

int
fhandler_socket_inet::getsockname (struct sockaddr *name, int *namelen)
{
  int res = -1;

  /* WinSock just returns WSAEFAULT if the buffer is too small.  Use a
     big enough local buffer and truncate later as necessary, per POSIX. */
  struct sockaddr_storage sock;
  int len = sizeof sock;
  res = ::getsockname (get_socket (), (struct sockaddr *) &sock, &len);
  if (!res)
    {
      memcpy (name, &sock, MIN (*namelen, len));
      *namelen = len;
    }
  else
    {
      if (WSAGetLastError () == WSAEINVAL)
	{
	  /* WinSock returns WSAEINVAL if the socket is locally
	     unbound.  Per SUSv3 this is not an error condition.
	     We're faking a valid return value here by creating the
	     same content in the sockaddr structure as on Linux. */
	  memset (&sock, 0, sizeof sock);
	  sock.ss_family = get_addr_family ();
	  switch (get_addr_family ())
	    {
	    case AF_INET:
	      res = 0;
	      len = (int) sizeof (struct sockaddr_in);
	      break;
	    case AF_INET6:
	      res = 0;
	      len = (int) sizeof (struct sockaddr_in6);
	      break;
	    default:
	      WSASetLastError (WSAEOPNOTSUPP);
	      break;
	    }
	  if (!res)
	    {
	      memcpy (name, &sock, MIN (*namelen, len));
	      *namelen = len;
	    }
	}
      if (res)
	set_winsock_errno ();
    }
  return res;
}

int
fhandler_socket_inet::getpeername (struct sockaddr *name, int *namelen)
{
  /* Always use a local big enough buffer and truncate later as necessary
     per POSIX.  WinSock unfortunately only returns WSAEFAULT if the buffer
     is too small. */
  struct sockaddr_storage sock;
  int len = sizeof sock;
  int res = ::getpeername (get_socket (), (struct sockaddr *) &sock, &len);
  if (res)
    set_winsock_errno ();
  else
    {
      memcpy (name, &sock, MIN (*namelen, len));
      *namelen = len;
    }
  return res;
}

/* There's no DLL which exports the symbol WSARecvMsg.  One has to call
   WSAIoctl as below to fetch the function pointer.  Why on earth did the
   MS developers decide not to export a normal symbol for these extension
   functions? */
inline int
get_ext_funcptr (SOCKET sock, void *funcptr)
{
  DWORD bret;
  const GUID guid = WSAID_WSARECVMSG;
  return WSAIoctl (sock, SIO_GET_EXTENSION_FUNCTION_POINTER,
		   (void *) &guid, sizeof (GUID), funcptr, sizeof (void *),
		   &bret, NULL, NULL);
}

inline ssize_t
fhandler_socket_inet::recv_internal (LPWSAMSG wsamsg, bool use_recvmsg)
{
  ssize_t res = 0;
  DWORD ret = 0, wret;
  int evt_mask = FD_READ | ((wsamsg->dwFlags & MSG_OOB) ? FD_OOB : 0);
  LPWSABUF &wsabuf = wsamsg->lpBuffers;
  ULONG &wsacnt = wsamsg->dwBufferCount;
  static NO_COPY LPFN_WSARECVMSG WSARecvMsg;

  /* CV 2014-10-26: Do not check for the connect_state at this point.  In
     certain scenarios there's no way to check the connect state reliably.
     Example (hexchat): Parent process creates socket, forks, child process
     calls connect, parent process calls read.  Even if the event handling
     allows to check for FD_CONNECT in the parent, there is always yet another
     scenario we can easily break. */

  DWORD wait_flags = wsamsg->dwFlags;
  bool waitall = !!(wait_flags & MSG_WAITALL);
  wsamsg->dwFlags &= (MSG_OOB | MSG_PEEK | MSG_DONTROUTE);
  if (use_recvmsg)
    {
      if (!WSARecvMsg
	  && get_ext_funcptr (get_socket (), &WSARecvMsg) == SOCKET_ERROR)
	{
	  if (wsamsg->Control.len > 0)
	    {
	      set_winsock_errno ();
	      return SOCKET_ERROR;
	    }
	  use_recvmsg = false;
	}
      else /* Only MSG_PEEK is supported by WSARecvMsg. */
	wsamsg->dwFlags &= MSG_PEEK;
    }
  if (waitall)
    {
      if (get_socket_type () != SOCK_STREAM)
	{
	  WSASetLastError (WSAEOPNOTSUPP);
	  set_winsock_errno ();
	  return SOCKET_ERROR;
	}
      if (is_nonblocking () || (wsamsg->dwFlags & (MSG_OOB | MSG_PEEK)))
	waitall = false;
    }

  /* Note: Don't call WSARecvFrom(MSG_PEEK) without actually having data
     waiting in the buffers, otherwise the event handling gets messed up
     for some reason. */
  while (!(res = wait_for_events (evt_mask | FD_CLOSE, wait_flags))
	 || saw_shutdown_read ())
    {
      if (use_recvmsg)
	res = WSARecvMsg (get_socket (), wsamsg, &wret, NULL, NULL);
      /* This is working around a really weird problem in WinSock.

	 Assume you create a socket, fork the process (thus duplicating
	 the socket), connect the socket in the child, then call recv
	 on the original socket handle in the parent process.
	 In this scenario, calls to WinSock's recvfrom and WSARecvFrom
	 in the parent will fail with WSAEINVAL, regardless whether both
	 address parameters, name and namelen, are NULL or point to valid
	 storage.  However, calls to recv and WSARecv succeed as expected.
	 Per MSDN, WSAEINVAL in the context of recv means  "The socket has not
	 been bound".  It is as if the recvfrom functions test if the socket
	 is bound locally, but in the parent process, WinSock doesn't know
	 about that and fails, while the same test is omitted in the recv
	 functions.

	 This also covers another weird case: WinSock returns WSAEFAULT if
	 namelen is a valid pointer while name is NULL.  Both parameters are
	 ignored for TCP sockets, so this only occurs when using UDP socket. */
      else if (!wsamsg->name || get_socket_type () == SOCK_STREAM)
	res = WSARecv (get_socket (), wsabuf, wsacnt, &wret, &wsamsg->dwFlags,
		       NULL, NULL);
      else
	res = WSARecvFrom (get_socket (), wsabuf, wsacnt, &wret,
			   &wsamsg->dwFlags, wsamsg->name, &wsamsg->namelen,
			   NULL, NULL);
      if (!res)
	{
	  ret += wret;
	  if (!waitall)
	    break;
	  while (wret && wsacnt)
	    {
	      if (wsabuf->len > wret)
		{
		  wsabuf->len -= wret;
		  wsabuf->buf += wret;
		  wret = 0;
		}
	      else
		{
		  wret -= wsabuf->len;
		  ++wsabuf;
		  --wsacnt;
		}
	    }
	  if (!wret)
	    break;
	}
      else if (WSAGetLastError () != WSAEWOULDBLOCK)
	break;
    }

  if (res)
    {
      /* According to SUSv3, errno isn't set in that case and no error
	 condition is returned. */
      if (WSAGetLastError () == WSAEMSGSIZE)
	ret += wret;
      else if (!ret)
	{
	  /* ESHUTDOWN isn't defined for recv in SUSv3.  Simply EOF is returned
	     in this case. */
	  if (WSAGetLastError () == WSAESHUTDOWN)
	    ret = 0;
	  else
	    {
	      set_winsock_errno ();
	      return SOCKET_ERROR;
	    }
	}
    }

  return ret;
}

ssize_t
fhandler_socket_inet::recvfrom (void *in_ptr, size_t len, int flags,
				struct sockaddr *from, int *fromlen)
{
  char *ptr = (char *) in_ptr;

#ifdef __x86_64__
  /* size_t is 64 bit, but the len member in WSABUF is 32 bit.
     Split buffer if necessary. */
  DWORD bufcnt = len / UINT32_MAX + ((!len || (len % UINT32_MAX)) ? 1 : 0);
  WSABUF wsabuf[bufcnt];
  WSAMSG wsamsg = { from, from && fromlen ? *fromlen : 0,
		    wsabuf, bufcnt,
		    { 0,  NULL },
		    (DWORD) flags };
  /* Don't use len as loop condition, it could be 0. */
  for (WSABUF *wsaptr = wsabuf; bufcnt--; ++wsaptr)
    {
      wsaptr->len = MIN (len, UINT32_MAX);
      wsaptr->buf = ptr;
      len -= wsaptr->len;
      ptr += wsaptr->len;
    }
#else
  WSABUF wsabuf = { len, ptr };
  WSAMSG wsamsg = { from, from && fromlen ? *fromlen : 0,
		    &wsabuf, 1,
		    { 0, NULL},
		    (DWORD) flags };
#endif
  ssize_t ret = recv_internal (&wsamsg, false);
  if (fromlen)
    *fromlen = wsamsg.namelen;
  return ret;
}

ssize_t
fhandler_socket_inet::recvmsg (struct msghdr *msg, int flags)
{
  /* Disappointing but true:  Even if WSARecvMsg is supported, it's only
     supported for datagram and raw sockets. */
  bool use_recvmsg = true;
  if (get_socket_type () == SOCK_STREAM || get_addr_family () == AF_LOCAL)
    {
      use_recvmsg = false;
      msg->msg_controllen = 0;
    }

  WSABUF wsabuf[msg->msg_iovlen];
  WSABUF *wsaptr = wsabuf + msg->msg_iovlen;
  const struct iovec *iovptr = msg->msg_iov + msg->msg_iovlen;
  while (--wsaptr >= wsabuf)
    {
      wsaptr->len = (--iovptr)->iov_len;
      wsaptr->buf = (char *) iovptr->iov_base;
    }
  WSAMSG wsamsg = { (struct sockaddr *) msg->msg_name, msg->msg_namelen,
		    wsabuf, (DWORD) msg->msg_iovlen,
		    { (DWORD) msg->msg_controllen, (char *) msg->msg_control },
		    (DWORD) flags };
  ssize_t ret = recv_internal (&wsamsg, use_recvmsg);
  if (ret >= 0)
    {
      msg->msg_namelen = wsamsg.namelen;
      msg->msg_controllen = wsamsg.Control.len;
      if (!CYGWIN_VERSION_CHECK_FOR_USING_ANCIENT_MSGHDR)
	msg->msg_flags = wsamsg.dwFlags;
    }
  return ret;
}

void __reg3
fhandler_socket_inet::read (void *in_ptr, size_t& len)
{
  char *ptr = (char *) in_ptr;

#ifdef __x86_64__
  /* size_t is 64 bit, but the len member in WSABUF is 32 bit.
     Split buffer if necessary. */
  DWORD bufcnt = len / UINT32_MAX + ((!len || (len % UINT32_MAX)) ? 1 : 0);
  WSABUF wsabuf[bufcnt];
  WSAMSG wsamsg = { NULL, 0, wsabuf, bufcnt, { 0,  NULL }, 0 };
  /* Don't use len as loop condition, it could be 0. */
  for (WSABUF *wsaptr = wsabuf; bufcnt--; ++wsaptr)
    {
      wsaptr->len = MIN (len, UINT32_MAX);
      wsaptr->buf = ptr;
      len -= wsaptr->len;
      ptr += wsaptr->len;
    }
#else
  WSABUF wsabuf = { len, ptr };
  WSAMSG wsamsg = { NULL, 0, &wsabuf, 1, { 0,  NULL }, 0 };
#endif

  len = recv_internal (&wsamsg, false);
}

ssize_t
fhandler_socket_inet::readv (const struct iovec *const iov, const int iovcnt,
			     ssize_t tot)
{
  WSABUF wsabuf[iovcnt];
  WSABUF *wsaptr = wsabuf + iovcnt;
  const struct iovec *iovptr = iov + iovcnt;
  while (--wsaptr >= wsabuf)
    {
      wsaptr->len = (--iovptr)->iov_len;
      wsaptr->buf = (char *) iovptr->iov_base;
    }
  WSAMSG wsamsg = { NULL, 0, wsabuf, (DWORD) iovcnt, { 0,  NULL}, 0 };
  return recv_internal (&wsamsg, false);
}

inline ssize_t
fhandler_socket_inet::send_internal (struct _WSAMSG *wsamsg, int flags)
{
  ssize_t res = 0;
  DWORD ret = 0, sum = 0;
  WSABUF out_buf[wsamsg->dwBufferCount];
  bool use_sendmsg = false;
  DWORD wait_flags = flags & MSG_DONTWAIT;
  bool nosignal = !!(flags & MSG_NOSIGNAL);

  flags &= (MSG_OOB | MSG_DONTROUTE);
  if (wsamsg->Control.len > 0)
    use_sendmsg = true;
  /* Workaround for MSDN KB 823764: Split a message into chunks <= SO_SNDBUF.
     in_idx is the index of the current lpBuffers from the input wsamsg buffer.
     in_off is used to keep track of the next byte to write from a wsamsg
     buffer which only gets partially written. */
  for (DWORD in_idx = 0, in_off = 0;
       in_idx < wsamsg->dwBufferCount;
       in_off >= wsamsg->lpBuffers[in_idx].len && (++in_idx, in_off = 0))
    {
      /* Split a message into the least number of pieces to minimize the
	 number of WsaSendTo calls.  Don't split datagram messages (bad idea).
	 out_idx is the index of the next buffer in the out_buf WSABUF,
	 also the number of buffers given to WSASendTo.
	 out_len is the number of bytes in the buffers given to WSASendTo.
	 Don't split datagram messages (very bad idea). */
      DWORD out_idx = 0;
      DWORD out_len = 0;
      if (get_socket_type () == SOCK_STREAM)
	{
	  do
	    {
	      out_buf[out_idx].buf = wsamsg->lpBuffers[in_idx].buf + in_off;
	      out_buf[out_idx].len = wsamsg->lpBuffers[in_idx].len - in_off;
	      out_len += out_buf[out_idx].len;
	      out_idx++;
	    }
	  while (out_len < (unsigned) wmem ()
		 && (in_off = 0, ++in_idx < wsamsg->dwBufferCount));
	  /* Tweak len of the last out_buf buffer so the entire number of bytes
	     is (less than or) equal to wmem ().  Fix out_len as well since it's
	     used in a subsequent test expression. */
	  if (out_len > (unsigned) wmem ())
	    {
	      out_buf[out_idx - 1].len -= out_len - (unsigned) wmem ();
	      out_len = (unsigned) wmem ();
	    }
	  /* Add the bytes written from the current last buffer to in_off,
	     so in_off points to the next byte to be written from that buffer,
	     or beyond which lets the outper loop skip to the next buffer. */
	  in_off += out_buf[out_idx - 1].len;
	}

      do
	{
	  if (use_sendmsg)
	    res = WSASendMsg (get_socket (), wsamsg, flags, &ret, NULL, NULL);
	  else if (get_socket_type () == SOCK_STREAM)
	    res = WSASendTo (get_socket (), out_buf, out_idx, &ret, flags,
			     wsamsg->name, wsamsg->namelen, NULL, NULL);
	  else
	    res = WSASendTo (get_socket (), wsamsg->lpBuffers,
			     wsamsg->dwBufferCount, &ret, flags,
			     wsamsg->name, wsamsg->namelen, NULL, NULL);
	  if (res && (WSAGetLastError () == WSAEWOULDBLOCK))
	    {
	      LOCK_EVENTS;
	      wsock_events->events &= ~FD_WRITE;
	      UNLOCK_EVENTS;
	    }
	}
      while (res && (WSAGetLastError () == WSAEWOULDBLOCK)
	     && !(res = wait_for_events (FD_WRITE | FD_CLOSE, wait_flags)));

      if (!res)
	{
	  sum += ret;
	  /* For streams, return to application if the number of bytes written
	     is less than the number of bytes we intended to write in a single
	     call to WSASendTo.  Otherwise we would have to add code to
	     backtrack in the input buffers, which is questionable.  There was
	     probably a good reason we couldn't write more. */
	  if (get_socket_type () != SOCK_STREAM || ret < out_len)
	    break;
	}
      else if (is_nonblocking () || WSAGetLastError() != WSAEWOULDBLOCK)
	break;
    }

  if (sum)
    res = sum;
  else if (res == SOCKET_ERROR)
    {
      set_winsock_errno ();

      /* Special handling for EPIPE and SIGPIPE.

	 EPIPE is generated if the local end has been shut down on a connection
	 oriented socket.  In this case the process will also receive a SIGPIPE
	 unless MSG_NOSIGNAL is set.  */
      if ((get_errno () == ECONNABORTED || get_errno () == ESHUTDOWN)
	  && get_socket_type () == SOCK_STREAM)
	{
	  set_errno (EPIPE);
	  if (!nosignal)
	    raise (SIGPIPE);
	}
    }

  return res;
}

ssize_t
fhandler_socket_inet::sendto (const void *in_ptr, size_t len, int flags,
			      const struct sockaddr *to, int tolen)
{
  char *ptr = (char *) in_ptr;
  struct sockaddr_storage sst;

  if (to && get_inet_addr_inet (to, tolen, &sst, &tolen) == SOCKET_ERROR)
    return SOCKET_ERROR;

#ifdef __x86_64__
  /* size_t is 64 bit, but the len member in WSABUF is 32 bit.
     Split buffer if necessary. */
  DWORD bufcnt = len / UINT32_MAX + ((!len || (len % UINT32_MAX)) ? 1 : 0);
  WSABUF wsabuf[bufcnt];
  WSAMSG wsamsg = { to ? (struct sockaddr *) &sst : NULL, tolen,
		    wsabuf, bufcnt,
		    { 0,  NULL },
		    0 };
  /* Don't use len as loop condition, it could be 0. */
  for (WSABUF *wsaptr = wsabuf; bufcnt--; ++wsaptr)
    {
      wsaptr->len = MIN (len, UINT32_MAX);
      wsaptr->buf = ptr;
      len -= wsaptr->len;
      ptr += wsaptr->len;
    }
#else
  WSABUF wsabuf = { len, ptr };
  WSAMSG wsamsg = { to ? (struct sockaddr *) &sst : NULL, tolen,
		    &wsabuf, 1,
		    { 0, NULL},
		    0 };
#endif
  return send_internal (&wsamsg, flags);
}

ssize_t
fhandler_socket_inet::sendmsg (const struct msghdr *msg, int flags)
{
  /* TODO: Descriptor passing on AF_LOCAL sockets. */

  struct sockaddr_storage sst;
  int len = 0;

  if (msg->msg_name
      && get_inet_addr_inet ((struct sockaddr *) msg->msg_name,
			     msg->msg_namelen, &sst, &len) == SOCKET_ERROR)
    return SOCKET_ERROR;

  WSABUF wsabuf[msg->msg_iovlen];
  WSABUF *wsaptr = wsabuf;
  const struct iovec *iovptr = msg->msg_iov;
  for (int i = 0; i < msg->msg_iovlen; ++i)
    {
      wsaptr->len = iovptr->iov_len;
      (wsaptr++)->buf = (char *) (iovptr++)->iov_base;
    }
  /* Disappointing but true:  Even if WSASendMsg is supported, it's only
     supported for datagram and raw sockets. */
  DWORD controllen = (DWORD) (get_socket_type () == SOCK_STREAM
			      || get_addr_family () == AF_LOCAL
			      ? 0 : msg->msg_controllen);
  WSAMSG wsamsg = { msg->msg_name ? (struct sockaddr *) &sst : NULL, len,
		    wsabuf, (DWORD) msg->msg_iovlen,
		    { controllen, (char *) msg->msg_control },
		    0 };
  return send_internal (&wsamsg, flags);
}

ssize_t
fhandler_socket_inet::write (const void *in_ptr, size_t len)
{
  char *ptr = (char *) in_ptr;

#ifdef __x86_64__
  /* size_t is 64 bit, but the len member in WSABUF is 32 bit.
     Split buffer if necessary. */
  DWORD bufcnt = len / UINT32_MAX + ((!len || (len % UINT32_MAX)) ? 1 : 0);
  WSABUF wsabuf[bufcnt];
  WSAMSG wsamsg = { NULL, 0, wsabuf, bufcnt, { 0,  NULL }, 0 };
  /* Don't use len as loop condition, it could be 0. */
  for (WSABUF *wsaptr = wsabuf; bufcnt--; ++wsaptr)
    {
      wsaptr->len = MIN (len, UINT32_MAX);
      wsaptr->buf = ptr;
      len -= wsaptr->len;
      ptr += wsaptr->len;
    }
#else
  WSABUF wsabuf = { len, ptr };
  WSAMSG wsamsg = { NULL, 0, &wsabuf, 1, { 0, NULL }, 0 };
#endif
  return send_internal (&wsamsg, 0);
}

ssize_t
fhandler_socket_inet::writev (const struct iovec *const iov, const int iovcnt,
			      ssize_t tot)
{
  WSABUF wsabuf[iovcnt];
  WSABUF *wsaptr = wsabuf;
  const struct iovec *iovptr = iov;
  for (int i = 0; i < iovcnt; ++i)
    {
      wsaptr->len = iovptr->iov_len;
      (wsaptr++)->buf = (char *) (iovptr++)->iov_base;
    }
  WSAMSG wsamsg = { NULL, 0, wsabuf, (DWORD) iovcnt, { 0, NULL}, 0 };
  return send_internal (&wsamsg, 0);
}

int
fhandler_socket_inet::setsockopt (int level, int optname, const void *optval,
				  socklen_t optlen)
{
  bool ignore = false;
  int ret = -1;

  /* Preprocessing setsockopt.  Set ignore to true if setsockopt call should
     get skipped entirely. */
  switch (level)
    {
    case SOL_SOCKET:
      switch (optname)
	{
	case SO_PEERCRED:
	  set_errno (ENOPROTOOPT);
	  return -1;

	case SO_REUSEADDR:
	  /* Per POSIX we must not be able to reuse a complete duplicate of a
	     local TCP address (same IP, same port), even if SO_REUSEADDR has
	     been set.  This behaviour is maintained in WinSock for backward
	     compatibility, while the WinSock standard behaviour of stream
	     socket binding is equivalent to the POSIX behaviour as if
	     SO_REUSEADDR has been set.  The SO_EXCLUSIVEADDRUSE option has
	     been added to allow an application to request POSIX standard
	     behaviour in the non-SO_REUSEADDR case.

	     To emulate POSIX socket binding behaviour, note that SO_REUSEADDR
	     has been set but don't call setsockopt.  Instead
	     fhandler_socket::bind sets SO_EXCLUSIVEADDRUSE if the application
	     did not set SO_REUSEADDR. */
	  if (optlen < (socklen_t) sizeof (int))
	    {
	      set_errno (EINVAL);
	      return ret;
	    }
	  if (get_socket_type () == SOCK_STREAM)
	    ignore = true;
	  break;

	case SO_RCVTIMEO:
	case SO_SNDTIMEO:
	  if (optlen < (socklen_t) sizeof (struct timeval))
	    {
	      set_errno (EINVAL);
	      return ret;
	    }
	  if (timeval_to_ms ((struct timeval *) optval,
			     (optname == SO_RCVTIMEO) ? rcvtimeo ()
						      : sndtimeo ()))
	    ret = 0;
	  else
	    set_errno (EDOM);
	  return ret;

	default:
	  break;
	}
      break;

    case IPPROTO_IP:
      /* Old applications still use the old WinSock1 IPPROTO_IP values. */
      if (CYGWIN_VERSION_CHECK_FOR_USING_WINSOCK1_VALUES)
	optname = convert_ws1_ip_optname (optname);
      switch (optname)
	{
	case IP_TOS:
	  /* Winsock doesn't support setting the IP_TOS field with setsockopt
	     and TOS was never implemented for TCP anyway.  setsockopt returns
	     WinSock error 10022, WSAEINVAL when trying to set the IP_TOS
	     field.  We just return 0 instead. */
	  ignore = true;
	  break;

	default:
	  break;
	}
      break;

    case IPPROTO_IPV6:
      {
      switch (optname)
	{
	case IPV6_TCLASS:
	  /* Unsupported */
	  ignore = true;
	  break;

	default:
	  break;
	}
      }
    default:
      break;
    }

  /* Call Winsock setsockopt (or not) */
  if (ignore)
    ret = 0;
  else
    {
      ret = ::setsockopt (get_socket (), level, optname, (const char *) optval,
			  optlen);
      if (ret == SOCKET_ERROR)
	{
	  set_winsock_errno ();
	  return ret;
	}
    }

  if (optlen == (socklen_t) sizeof (int))
    debug_printf ("setsockopt optval=%x", *(int *) optval);

  /* Postprocessing setsockopt, setting fhandler_socket members, etc. */
  switch (level)
    {
    case SOL_SOCKET:
      switch (optname)
	{
	case SO_REUSEADDR:
	  saw_reuseaddr (*(int *) optval);
	  break;

	case SO_RCVBUF:
	  rmem (*(int *) optval);
	  break;

	case SO_SNDBUF:
	  wmem (*(int *) optval);
	  break;

	default:
	  break;
	}
      break;

    default:
      break;
    }

  return ret;
}

int
fhandler_socket_inet::getsockopt (int level, int optname, const void *optval,
				  socklen_t *optlen)
{
  bool onebyte = false;
  int ret = -1;

  /* Preprocessing getsockopt. */
  switch (level)
    {
    case SOL_SOCKET:
      switch (optname)
	{
	case SO_PEERCRED:
	  set_errno (ENOPROTOOPT);
	  return -1;

	case SO_REUSEADDR:
	  {
	    unsigned int *reuseaddr = (unsigned int *) optval;

	    if (*optlen < (socklen_t) sizeof *reuseaddr)
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    *reuseaddr = saw_reuseaddr();
	    *optlen = (socklen_t) sizeof *reuseaddr;
	    return 0;
	  }

	case SO_RCVTIMEO:
	case SO_SNDTIMEO:
	  {
	    struct timeval *time_out = (struct timeval *) optval;

	    if (*optlen < (socklen_t) sizeof *time_out)
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    DWORD ms = (optname == SO_RCVTIMEO) ? rcvtimeo () : sndtimeo ();
	    if (ms == 0 || ms == INFINITE)
	      {
		time_out->tv_sec = 0;
		time_out->tv_usec = 0;
	      }
	    else
	      {
		time_out->tv_sec = ms / MSPERSEC;
		time_out->tv_usec = ((ms % MSPERSEC) * USPERSEC) / MSPERSEC;
	      }
	    *optlen = (socklen_t) sizeof *time_out;
	    return 0;
	  }

	case SO_TYPE:
	  {
	    unsigned int *type = (unsigned int *) optval;
	    *type = get_socket_type ();
	    *optlen = (socklen_t) sizeof *type;
	    return 0;
	  }

	default:
	  break;
	}
      break;

    case IPPROTO_IP:
      /* Old applications still use the old WinSock1 IPPROTO_IP values. */
      if (CYGWIN_VERSION_CHECK_FOR_USING_WINSOCK1_VALUES)
	optname = convert_ws1_ip_optname (optname);
      break;

    default:
      break;
    }

  /* Call Winsock getsockopt */
  ret = ::getsockopt (get_socket (), level, optname, (char *) optval,
		      (int *) optlen);
  if (ret == SOCKET_ERROR)
    {
      set_winsock_errno ();
      return ret;
    }

  /* Postprocessing getsockopt, setting fhandler_socket members, etc.  Set
     onebyte true for options returning BOOLEAN instead of a boolean DWORD. */
  switch (level)
    {
    case SOL_SOCKET:
      switch (optname)
	{
	case SO_ERROR:
	  {
	    int *e = (int *) optval;
	    debug_printf ("WinSock SO_ERROR = %d", *e);
	    *e = find_winsock_errno (*e);
	  }
	  break;

	case SO_KEEPALIVE:
	case SO_DONTROUTE:
	  onebyte = true;
	  break;

	default:
	  break;
	}
      break;
    case IPPROTO_TCP:
      switch (optname)
	{
	case TCP_NODELAY:
	  onebyte = true;
	  break;

	default:
	  break;
	}
    default:
      break;
    }

  if (onebyte)
    {
      /* Regression in Vista and later: instead of a 4 byte BOOL value, a
	 1 byte BOOLEAN value is returned, in contrast to older systems and
	 the documentation.  Since an int type is expected by the calling
	 application, we convert the result here.  For some reason only three
	 BSD-compatible socket options seem to be affected. */
      BOOLEAN *in = (BOOLEAN *) optval;
      int *out = (int *) optval;
      *out = *in;
      *optlen = 4;
    }

  return ret;
}