sendmsg() -- send message from socket using structure

SYNOPSIS

#include <sys/socket.h>

int sendmsg(int s, const struct msghdr *msg, int flags);

The sendmsg() 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 msghdr. If s is a connection oriented socket, the destination address in msghdr is ignored.

If the message is too long to pass through the underlying protocol, sendmsg() fails and no data is transmitted.

Successful completion of sendmsg() 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, sendmsg() 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, sendmsg() 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.
message: Points to a msghdr structure which contains both a pointer to the buffer containing the destination address, and the address of the buffers which contains the message to be transmitted. The msg_flags field is ignored.
flags: Lets the sender control the way data is sent.

RETURN VALUES

If successful, sendmsg() 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.
EMSGSIZE: Message size is too big to be sent atomically.
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.
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 sendmsg() 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 sendmsg() would block.

sendmsg()
send message from socket using structure

Function

SYNOPSIS

DESCRIPTION

PARAMETERS

RETURN VALUES

CONFORMANCE

MULTITHREAD SAFETY LEVEL

PORTING ISSUES

AVAILABILITY

SEE ALSO

sendmsg() send message from socket using structure

Function

sendmsg()
send message from socket using structure