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/*
* The Unix Channel
*
* by Michel Beaudouin-Lafon
*
* Copyright 1990-1993
* Laboratoire de Recherche en Informatique (LRI)
*
* Datagrams
*
* $Id$
* $CurLog$
*/
#include "Datagram.h"
#include "MsgBuffer.h"
#include <stdlib.h>
#include <sys/socket.h>
/*?class UchDatagram
A datagram socket can send to and receive from any other datagram socket,
unless it is connected.
Thus, establishing a datagram connection is simple.
UchDatagram sockets are not reliable: messages can be lost, duplicated, or be received in a different order.
They keep the message boundaries: when \var{n} bytes are written, you will read at most \var{n} bytes;
but if you ask to read less than \var{n} bytes, then the end of the message will be lost.
When a datagram socket is not connected, you must provide an address when you send a message;
when a message is read, the address of the sender can be retrieved (with function \fun{From}).
When a datagram socket is connected, messages can only be sent to and read from the
connected address. The \fun{Read} and \fun{Write} calls can be used in this case.
Before any data can be sent or received, the socket must be set up with \fun{Setup}.
?*/
/*?nextdoc?*/
UchDatagram :: UchDatagram ()
: UchSocket (),
FAddr (0)
{
}
/*?
These constructors are similar to those of the class \typ{UchSocket}.
?*/
UchDatagram :: UchDatagram (UchAddress* bound, UchAddress* connected)
: UchSocket (bound, connected),
FAddr (0)
{
}
/*?nodoc?*/
UchDatagram :: UchDatagram (const UchDatagram& d)
: UchSocket (d),
FAddr (d.FAddr)
{
}
/*?nodoc?*/
UchDatagram :: ~UchDatagram ()
{
}
#ifdef DOC
/*?
Return the address of the sender of the last received message.
?*/
UchAddress*
UchDatagram :: From ()
{ }
#endif /* DOC */
/*?nodoc?*/
UchChannel*
UchDatagram :: Copy () const
{
return new UchDatagram (*this);
}
/*?nodoc?*/
int
UchDatagram :: SockType ()
{
return SOCK_DGRAM;
}
/*?
Send \var{len} bytes of \var{buf} on the datagram, to a destination address \var{to}.
Return the number of bytes actually transferred, or -1 if a system error occurred.
If the datagram is connected, you must use \fun{Write} instead.
?*/
int
UchDatagram :: Send (byte* buf, int len, UchAddress& to)
{
return sendto (FilDes (), (char*) buf, len, 0, to.GetSockAddr (), to.Length ());
}
/*?
Receive at most \var{len} bytes into \var{buf}.
Return the number of bytes actually transferred, or -1 if a system error occurred.
The address of the sender can be retrieved with \fun{From}.
If the socket is connected, you must use \fun{Read} instead.
?*/
int
UchDatagram :: Receive (byte* buf, int len)
{
GEN_ADDR addr;
int alen = sizeof (addr);
int ret;
ret = recvfrom (FilDes (), (char*) buf, len, 0, &addr.sa, &alen);
if (ret < 0)
return ret;
FAddr = UchAddress::Decode (&addr, alen);
return ret;
}
/*?
This is equivalent to \fun{Send(buf, len, From ())}:
it sends \fun{len} bytes to the sender of the last received message.
If there is no such sender, it returns -1.
?*/
int
UchDatagram :: Reply (byte* buf, int len)
{
if (! FAddr)
return -1;
return sendto (FilDes (), (char*) buf, len, 0, FAddr->GetSockAddr (), FAddr->Length ());
}
/*?nextdoc?*/
int
UchDatagram :: Send (UchMsgBuffer& buf, UchAddress& to, bool peek)
{
int n = Send (buf.Buffer (), buf.BufLength (), to);
if (! peek)
buf.Flush (n);
return n;
}
/*?nextdoc?*/
int
UchDatagram :: Receive (UchMsgBuffer& buf)
{
int n = Receive (buf.Free (), buf.FreeLength ());
if (n > 0)
buf.More (n);
return n;
}
/*?
The same functions but with a \typ{UchMsgBuffer} argument instead of a byte pointer and size.
As usual, if \var{peek} is TRUE the buffer is not flushed.
?*/
int
UchDatagram :: Reply (UchMsgBuffer& buf, bool peek)
{
int n = Reply (buf.Buffer (), buf.BufLength ());
if (! peek)
buf.Flush (n);
return n;
}
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