162 lines
4.8 KiB
Groff
162 lines
4.8 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
|
|
.\" The Regents of the University of California. 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. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
|
|
.\"
|
|
.\" @(#)send.2 8.2 (Berkeley) 2/21/94
|
|
.\"
|
|
.Dd February 21, 1994
|
|
.Dt SEND 2
|
|
.Os BSD 4.2
|
|
.Sh NAME
|
|
.Nm send ,
|
|
.Nm sendto ,
|
|
.Nm sendmsg
|
|
.Nd send a message from a socket
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/types.h>
|
|
.Fd #include <sys/socket.h>
|
|
.Ft ssize_t
|
|
.Fn send "int s" "const void *msg" "size_t len" "int flags"
|
|
.Ft ssize_t
|
|
.Fn sendto "int s" "const void *msg" "size_t len" "int flags" "const struct sockaddr *to" "int tolen"
|
|
.Ft ssize_t
|
|
.Fn sendmsg "int s" "const struct msghdr *msg" "int flags"
|
|
.Sh DESCRIPTION
|
|
.Fn Send ,
|
|
.Fn sendto ,
|
|
and
|
|
.Fn sendmsg
|
|
are used to transmit a message to another socket.
|
|
.Fn Send
|
|
may be used only when the socket is in a
|
|
.Em connected
|
|
state, while
|
|
.Fn sendto
|
|
and
|
|
.Fn sendmsg
|
|
may be used at any time.
|
|
.Pp
|
|
The address of the target is given by
|
|
.Fa to
|
|
with
|
|
.Fa tolen
|
|
specifying its size.
|
|
The length of the message is given by
|
|
.Fa len .
|
|
If the message is too long to pass atomically through the
|
|
underlying protocol, the error
|
|
.Er EMSGSIZE
|
|
is returned, and
|
|
the message is not transmitted.
|
|
.Pp
|
|
No indication of failure to deliver is implicit in a
|
|
.Fn send .
|
|
Locally detected errors are indicated by a return value of -1.
|
|
.Pp
|
|
If no messages space is available at the socket to hold
|
|
the message to be transmitted, then
|
|
.Fn send
|
|
normally blocks, unless the socket has been placed in
|
|
non-blocking I/O mode.
|
|
The
|
|
.Xr select 2
|
|
call may be used to determine when it is possible to
|
|
send more data.
|
|
.Pp
|
|
The
|
|
.Fa flags
|
|
parameter may include one or more of the following:
|
|
.Bd -literal
|
|
#define MSG_OOB 0x1 /* process out-of-band data */
|
|
#define MSG_DONTROUTE 0x4 /* bypass routing, use direct interface */
|
|
.Ed
|
|
.Pp
|
|
The flag
|
|
.Dv MSG_OOB
|
|
is used to send
|
|
.Dq out-of-band
|
|
data on sockets that support this notion (e.g.
|
|
.Dv SOCK_STREAM ) ;
|
|
the underlying protocol must also support
|
|
.Dq out-of-band
|
|
data.
|
|
.Dv MSG_DONTROUTE
|
|
is usually used only by diagnostic or routing programs.
|
|
.Pp
|
|
See
|
|
.Xr recv 2
|
|
for a description of the
|
|
.Fa msghdr
|
|
structure.
|
|
.Sh RETURN VALUES
|
|
The call returns the number of characters sent, or -1
|
|
if an error occurred.
|
|
.Sh ERRORS
|
|
.Fn Send ,
|
|
.Fn sendto ,
|
|
and
|
|
.Fn sendmsg
|
|
fail if:
|
|
.Bl -tag -width [EMSGSIZE]
|
|
.It Bq Er EBADF
|
|
An invalid descriptor was specified.
|
|
.It Bq Er ENOTSOCK
|
|
The argument
|
|
.Fa s
|
|
is not a socket.
|
|
.It Bq Er EFAULT
|
|
An invalid user space address was specified for a parameter.
|
|
.It Bq Er EMSGSIZE
|
|
The socket requires that message be sent atomically,
|
|
and the size of the message to be sent made this impossible.
|
|
.It Bq Er EAGAIN
|
|
The socket is marked non-blocking and the requested operation
|
|
would block.
|
|
.It Bq Er ENOBUFS
|
|
The system was unable to allocate an internal buffer.
|
|
The operation may succeed when buffers become available.
|
|
.It Bq Er ENOBUFS
|
|
The output queue for a network interface was full.
|
|
This generally indicates that the interface has stopped sending,
|
|
but may be caused by transient congestion.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr fcntl 2 ,
|
|
.Xr recv 2 ,
|
|
.Xr select 2 ,
|
|
.Xr getsockopt 2 ,
|
|
.Xr socket 2 ,
|
|
.Xr write 2
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
function call appeared in
|
|
.Bx 4.2 .
|