sendto() -- send message from socket

SYNOPSIS

#include <sys/socket.h>

int sendto(int s, const void *msg, size_t len, int flags, const struct sockaddr *to, socklen_t tolen);

The sendto() function sends a message through a connection oriented or connectionless socket. If s is a connectionless socket, the message is sent to the address specified by to. If s is a connection oriented socket, to and tolen parameters are ignored.

If the socket protocol supports broadcast and the specified address is a broadcast address for the socket protocol, sendto() fails if the SO_BROADCAST option is not set for the socket.

The to argument specifies the address of the target. The len argument specifies the length of the message. If the message is too long to pass through the underlying protocol, sendto() fails and no data is transmitted.

Successful completion of 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 available at the sending socket to hold the message to be transmitted and the socket file descriptor does have O_NONBLOCK set, sendto() fails. Use the select() call to determine when more data can be sent.

flags may be used to influence the behavior of the function invocation beyond the options specified for the associated socket. That is, the semantics of this function are determined by the socket options and the flags parameter. The latter is constructed by or-ing any of the following values:

MSG_DONTROUTE: Specifies that the data should not be subject to routing.
MSG_OOB: Send out-of-band data (stream-style socket such as SOCK_STREAM only).

PARAMETERS

s: Specifies a socket descriptor.
msg: Points to a buffer containing the data to be transmitted.
len: Specifies the number of bytes to be sent.
flags: Lets the sender control the way data is sent.
to: Specifies the destination address.
tolen: Specifies the destination address size.

RETURN VALUES

If successful, sendto() returns the number of characters sent. If an error occurs, it returns a value of -1 and sets errno to one of the following:

EADDRNOTAVAIL: The specified address is not available from the local machine.
EBADF: s is an invalid descriptor.
ECONNABORTED: Connection was aborted due to timeout or other failure.
ECONNRESET: Connection was forcibly reset by the peer.
EDESTADDRREQ: A destination address is required.
EFAULT: msg points to an unreadable location.
EHOSTUNREACH: The remote host cannot be reached from this host at this time.
EINVAL: An unknown flag was specified, or MSG_OOB was specified for a socket with SO_OOBINLINE enabled.
EINTR: A signal interrupted the call.
ENETDOWN: The network subsystem has failed.
ENOBUFS: No buffer space is available.
ENOTCONN: The socket is not connected. (connection oriented sockets only.)
ENOTSOCK: s is not a socket descriptor.
EMSGSIZE: Message size is too big to be sent atomically.
EOPNOTSUPP: MSG_OOB was specified, but the socket is not stream style such as type SOCK_STREAM, out-of-band data is not supported in the communication domain associated with this socket, or the socket is unidirectional and supports only receive operations.
ESHUTDOWN: The socket has been shutdown; it is not possible to sendto() on a socket after shutdown() has been invoked with how set to SD_SEND or SD_BOTH.
ETIMEDOUT: Connection has been dropped, because of a network failure or because the system on the other end went down without notice.
EWOULDBLOCK: s is nonblocking and sendto() would block.

sendto()
send message from socket

Function

SYNOPSIS

DESCRIPTION

PARAMETERS

RETURN VALUES

CONFORMANCE

MULTITHREAD SAFETY LEVEL

PORTING ISSUES

AVAILABILITY

SEE ALSO

sendto() send message from socket

Function

sendto()
send message from socket