Subject: doubt regarding socket options

From: Jayabharathi <[email-masked]>
Date: Mon, 22 Dec 2003 15:54:43 +0530

Does the socket options like Destination, Hop-by-hop, and routing header are only used for Raw sockets or needed for all other sockets also???

If they are to be implemented with the other sockets also (STREAM and DATAGRAM ), how does applications receive and use the received option information.

In the same way how does we send the same using send / sendto.

regds
Jaya

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From: JINMEI Tatuya / 神明達哉 <[email-masked]>
Date: Thu, 25 Dec 2003 20:18:29 +0900

(I've folded some long lines of the original message)

>>>>> On Mon, 22 Dec 2003 15:54:43 +0530, 
>>>>> Jayabharathi <[email-masked]> said:

> Does the socket options like Destination, Hop-by-hop, and routing
> header are only used for Raw sockets or needed for all other sockets
> also???

I'm not sure what you meant by "needed", but:

As for the receiving side:
RFC3542, or at least the intention of the RFC, specifies an
application should also be able to get received destination
options/hop-by-hop options/routing header(s) on a UDP socket.
However, it intentionally leaves the implication for a TCP socket as
undefined.

As for the sending side:
RFC3542 specifies an application should be able to send packets with
extension headers on any kinds of socket; UDP, TCP, or raw.

> If they are to be implemented with the other sockets also (STREAM
> and DATAGRAM ), how does applications receive and use the received
> option information.

Regarding a UDP socket, the usage is exactly same as that for a raw
socket: use ancillary data items with recvmsg().

> In the same way how does we send the same using send / sendto.

Via ancillary data items or socket options.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]

p.s. I'd strongly recommend you to read RFC3542 first, if not yet.

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