In the following example, the lrs_set_send_buffer function sets the buffer containing the data for socket2. Note that 10 bytes from Buffer are sent on the socket, and not the buffer referenced by "buf21".
/* Set the buffer value. */
lrs_receive("socket2", "buf20", LrsLastArg);
lrs_get_last_received_buffer("socket2", &Buffer, &Size);
/* Make modifications on the last received buffer. */
. . .
lrs_set_send_buffer("socket2", Buffer, 10 );
lrs_send("socket2","buf21", LrsLastArg );