1 .\" Copyright (c) 1983, 1991, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. All advertising materials mentioning features or use of this software
13 .\" must display the following acknowledgement:
14 .\" This product includes software developed by the University of
15 .\" California, Berkeley and its contributors.
16 .\" 4. Neither the name of the University nor the names of its contributors
17 .\" may be used to endorse or promote products derived from this software
18 .\" without specific prior written permission.
20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 .\" From: @(#)send.2 8.2 (Berkeley) 2/21/94
33 .\" $FreeBSD: src/lib/libc/sys/send.2,v 1.10.2.6 2001/12/14 18:34:01 ru Exp $
34 .\" $DragonFly: src/lib/libc/sys/send.2,v 1.9 2007/06/30 19:03:52 swildner Exp $
43 .Nd send a message from a socket
50 .Fn send "int s" "const void *msgbuf" "size_t len" "int flags"
52 .Fn sendto "int s" "const void *msgbuf" "size_t len" "int flags" "const struct sockaddr *to" "socklen_t tolen"
54 .Fn sendmsg "int s" "const struct msghdr *msg" "int flags"
60 are used to transmit a message to another socket.
62 may be used only when the socket is in a
68 may be used at any time.
70 The socket file descriptor is given by
73 points to a buffer containing the message.
78 The address of the target is given by
83 The length of the message is given by
85 If the message is too long to pass atomically through the
86 underlying protocol, the error
89 the message is not transmitted.
91 No indication of failure to deliver is implicit in a
93 Locally detected errors are indicated by a return value of -1.
95 If no messages space is available at the socket to hold
96 the message to be transmitted, then
98 normally blocks, unless the socket has been placed in
99 non-blocking I/O mode.
102 call may be used to determine when it is possible to
107 parameter may include one or more of the following:
109 #define MSG_OOB 0x1 /* process out-of-band data */
110 #define MSG_PEEK 0x2 /* peek at incoming message */
111 #define MSG_DONTROUTE 0x4 /* bypass routing, use direct interface */
112 #define MSG_EOR 0x8 /* data completes record */
113 #define MSG_EOF 0x100 /* data completes transaction */
120 data on sockets that support this notion (e.g.\&
122 the underlying protocol must also support
126 is used to indicate a record mark for protocols which support the
129 requests that the sender side of a socket be shut down, and that an
130 appropriate indication be sent at the end of the specified data;
131 this flag is only implemented for
137 is usually used only by diagnostic or routing programs.
141 for a description of the
145 Upon successful completion the number of characters which were sent is
146 returned. Otherwise -1 is returned and the global variable
148 is set to indicate the error.
157 An invalid descriptor was specified.
159 The destination address is a broadcast address, and
161 has not been set on the socket.
167 An invalid user space address was specified for a parameter.
169 The socket requires that message be sent atomically,
170 and the size of the message to be sent made this impossible.
172 The socket is marked non-blocking and the requested operation
175 The system was unable to allocate an internal buffer.
176 The operation may succeed when buffers become available.
178 The output queue for a network interface was full.
179 This generally indicates that the interface has stopped sending,
180 but may be caused by transient congestion.
181 .It Bq Er EHOSTUNREACH
182 The remote host was unreachable.
183 .It Bq Er ECONNREFUSED
184 The socket received an ICMP destination unreachable message
185 from the last message sent. This typically means that the
186 receiver is not listening on the remote port.
188 The remote host was down.
190 The socket is unable to send anymore data (SS_CANTSENDMORE has
191 been set on the socket). This typically means that the socket
204 function call appeared in
209 doesn't necessarily block until the data has been transferred, it
210 is possible to transfer an open file descriptor across an
217 it before it has actually been sent, the result being that the receiver
218 gets a closed file descriptor. It is left to the application to
219 implement an acknowledgment mechanism to prevent this from happening.