sendto(3XNET) X/Open Networking Services Library Functions sendto(3XNET)NAMEsendto - send a message on a socket
SYNOPSIS
cc [ flag... ] file... -lxnet [ library ... ]
#include <sys/socket.h>
ssize_t sendto(int socket, const void *message, size_t length, int
flags, const struct sockaddr *dest_addr, socklen_t dest_len);
DESCRIPTION
The sendto() function sends a message through a connection-mode or con‐
nectionless-mode socket. If the socket is connectionless-mode, the
message will be sent to the address specified by dest_addr. If the
socket is connection-mode, dest_addr is ignored.
If the socket protocol supports broadcast and the specified address is
a broadcast address for the socket protocol, sendto() will fail if the
SO_BROADCAST option is not set for the socket.
The dest_addr argument specifies the address of the target. The length
argument specifies the length of the message.
Successful completion of a call to sendto() does not guarantee delivery
of the message. A return value of −1 indicates only locally-detected
errors.
If space is not available at the sending socket to hold the message to
be transmitted and the socket file descriptor does not have O_NONBLOCK
set, sendto() blocks until space is available. If space is not avail‐
able at the sending socket to hold the message to be transmitted and
the socket file descriptor does have O_NONBLOCK set, sendto() will
fail.
The socket in use may require the process to have appropriate privi‐
leges to use the sendto() function.
PARAMETERS
The function takes the following arguments:
socket Specifies the socket file descriptor.
message Points to a buffer containing the message to be sent.
length Specifies the size of the message in bytes.
flags Specifies the type of message transmission. Values of
this argument are formed by logically OR'ing zero or
more of the following flags:
MSG_EOR Terminates a record (if supported by
the protocol)
MSG_OOB Sends out-of-band data on sockets that
support out-of-band data. The signifi‐
cance and semantics of out-of-band data
are protocol-specific.
dest_addr Points to a sockaddr structure containing the destina‐
tion address. The length and format of the address
depend on the address family of the socket.
dest_len Specifies the length of the sockaddr structure pointed
to by the dest_addr argument.
USAGE
The select(3C) and poll(2) functions can be used to determine when it
is possible to send more data.
RETURN VALUES
Upon successful completion, sendto() returns the number of bytes sent.
Otherwise, -1 is returned and errno is set to indicate the error.
ERRORS
The sendto() function will fail if:
EAFNOSUPPORT Addresses in the specified address family can‐
not be used with this socket.
EAGAIN The socket's file descriptor is marked O_NON‐
EWOULDBLOCK BLOCK and the requested operation would block.
EBADF The socket argument is not a valid file
descriptor.
ECONNRESET A connection was forcibly closed by a peer.
EFAULT The message or destaddr parameter cannot be
accessed.
EINTR A signal interrupted sendto() before any data
was transmitted.
EMSGSIZE The message is too large to be sent all at
once, as the socket requires.
ENOTCONN The socket is connection-mode but is not con‐
nected.
ENOTSOCK The socket argument does not refer to a socket.
EOPNOTSUPP The socket argument is associated with a socket
that does not support one or more of the values
set in flags.
EPIPE The socket is shut down for writing, or the
socket is connection-mode and is no longer con‐
nected. In the latter case, and if the socket
is of type SOCK_STREAM, the SIGPIPE signal is
generated to the calling thread.
If the address family of the socket is AF_UNIX, then sendto() will fail
if:
EIO An I/O error occurred while reading from or
writing to the file system.
ELOOP Too many symbolic links were encountered in
translating the pathname in the socket address.
ENAMETOOLONG A component of a pathname exceeded NAME_MAX
characters, or an entire pathname exceeded
PATH_MAX characters.
ENOENT A component of the pathname does not name an
existing file or the pathname is an empty
string.
ENOTDIR A component of the path prefix of the pathname
in the socket address is not a directory.
The sendto() function may fail if:
EACCES Search permission is denied for a component of
the path prefix; or write access to the named
socket is denied.
EDESTADDRREQ The socket is not connection-mode and does not
have its peer address set, and no destination
address was specified.
EHOSTUNREACH The destination host cannot be reached (proba‐
bly because the host is down or a remote router
cannot reach it).
EINVAL The dest_len argument is not a valid length for
the address family.
EIO An I/O error occurred while reading from or
writing to the file system.
EISCONN A destination address was specified and the
socket is already connected.
ENETDOWN The local interface used to reach the destina‐
tion is down.
ENETUNREACH No route to the network is present.
ENOBUFS Insufficient resources were available in the
system to perform the operation.
ENOMEM Insufficient memory was available to fulfill
the request.
ENOSR There were insufficient STREAMS resources
available for the operation to complete.
If the address family of the socket is AF_UNIX, then sendto() may fail
if:
ENAMETOOLONG Pathname resolution of a symbolic link produced
an intermediate result whose length exceeds
PATH_MAX.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOpoll(2), getsockopt(3XNET), recv(3XNET), recvfrom(3XNET),
recvmsg(3XNET), select(3C), send(3XNET), sendmsg(3XNET), setsock‐
opt(3XNET), shutdown(3XNET), socket(3XNET), attributes(5), standards(5)SunOS 5.10 1 Nov 2003 sendto(3XNET)
