send

send transmits a message on a connected socket.

Syntax

int send(
    __in SOCKET s,
    __in const char *buf,
    __in int len,
    __in int flags
);

Parameters

Socket descriptor identifying connected socket.

buf

Pointer to a character buffer that holds the data to send.

len

An integer that defines the size in bytes of buf.

flags

A set of flags arguments that is logical OR of one or more of the following:

Flag	Description
MSG_DONTROUTE	Send without using routing tables.
MSG_OOB	Process urgent data, SOCK_STREAM only.
MSG_FDBROADCAST*	Send a full duplex broadcast. This flag causes a broadcast packet to be received by this node also. The default is not to receive your own broadcasts.

*Included in RtTcpIp.h header file

Return Values

The number of bytes sent if the function succeeds, SOCKET_ERROR if the function fails

Use WSAGetLastError to retrieve a specific error code.

Remarks

If there is insufficient space in the socket send queue to hold all the user data then, for blocking sockets, the send routines will block the calling process until space becomes available. On TCP sockets or on UDP, if there is no space available in the send queue, a value of SOCKET_ERROR is returned and WSAEWOULDBLOCK is the last error set.

The length of the message is indicated by the len parameter. If the message is too long to pass through the underlying protocol and the protocol does not support fragmentation, SOCKET_ERROR is returned and WSAEMSGSIZE is the last error set.

Successful completion of send does not imply successful reception of the message by the target host. For most protocols, a return value of SOCKET_ERROR indicates some locally detected error. Use select function to determine when it is possible to send more data.

| |