sendmsg(3N)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | ATTRIBUTES | SUMMARY OF TRUSTED SOLARIS CHANGES | SEE ALSO

NAME

send, sendto, sendmsg- Send a message from a socket

SYNOPSIS

cc [flags...] file ... -lsocket -lnsl [library...]


#include <sys/types.h>
#include <sys/socket.h>

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

DESCRIPTION

send() , sendto() , and sendmsg() are used to transmit a message to another transport end-point. send() may be used only when the socket is in a connected state, while sendto() and sendmsg() may be used at any time. s is a socket created with socket(3N) .

The address of the target is given by to with tolen specifying its size. The length of the message is given by len . If the message is too long to pass atomically through the underlying protocol, then the error EMSGSIZE is returned, and the message is not transmitted.

A return value of -1 indicates locally detected errors only. It does not implicitly mean the message was not delivered.

If the socket does not have enough buffer space available to hold the message being sent, send() blocks, unless the socket has been placed in non-blocking I/O mode (see fcntl(2) ). The select(3C) or poll(2) call may be used to determine when it is possible to send more data.

The flags parameter is formed from the bitwise OR of zero or more of the following:

MSG_OOB

Send "out-of-band" data on sockets that support this notion. The underlying protocol must also support "out-of-band" data. Only SOCK_STREAM sockets created in the AF_INET address family support out-of-band data.

MSG_DONTROUTE

The SO_DONTROUTE option is turned on for the duration of the operation. It is used only by diagnostic or routing programs.

See recv(3N) , for a description of the msghdr structure.

RETURN VALUES

These calls return the number of bytes sent, or -1 if an error occurred.

ERRORS

The calls fail if:

EBADF

s is an invalid file descriptor.

EINTR

The operation was interrupted by delivery of a signal before any data could be buffered to be sent.

EINVAL

tolen is not the size of a valid address for the specified address family.

EMSGSIZE

The socket requires that message be sent atomically, and the message was too long.

ENOMEM

There was insufficient memory available to complete the operation.

ENOSR

There were insufficient STREAMS resources available for the operation to complete.

ENOTSOCK

s is not a socket.

EWOULDBLOCK

The socket is marked non-blocking and the requested operation would block.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
MT-Level	Safe

SUMMARY OF TRUSTED SOLARIS CHANGES

If the process calling these routines possesses the PRIV_NET_REPLY_EQUAL privilege, the packets the process sends will carry the same CMW label as that of the last packet received from the destination. If no packet from the destination has ever been received, this privilege has no effect.

SEE ALSO

Trusted Solaris 7 Reference Manual

fcntl(2) , write(2) , getsockopt(3N)

SunOS 5.7 Reference Manual

poll(2) , select(3C) , recv(3N) , socket(3N) , attributes(5) , socket(5)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | ATTRIBUTES | SUMMARY OF TRUSTED SOLARIS CHANGES | SEE ALSO