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[REBOL] Re: Rebol and UDP

From: holger:rebol at: 25-Nov-2000 18:07

On Sun, Nov 26, 2000 at 02:31:13AM +0100, Petr Krenzelok wrote:
> REBOL > would have to store packet identifiers in a block somewhere in port object > structure, till you read out related data out of the buffer. Hmm, now as I > think about it - without such functionality, UDP implementation in REBOL is > pretty useless then, no? Holger?
No, see my other mail. The UDP protocol carries identifiers in the payload, not in the header. The UDP header only contains port numbers, length and checksum, no ID.
> Also - port/state/flags doesn't seem to be "real" IP datagram flag > representation (SYN,ACK,URG,FIN,RST)
Confusion, confusion... :-) SYN,ACK,URG,FIN,RST are TCP flags, not IP (or UDP) flags. They are used internally within the TCP/IP stack, never exported via APIs. UDP does not have any flags in its header at all. IP does have flags in its header, but they are used to reassemble IP fragments (within the TCP/IP stack) only, and are not useful at the application level. The stack processes them by itself anyway. port/state/flags is an internal field that indicates the mode of operation at the REBOL port level. It is used to indicate things like "direct", binary , "lines" mode etc., and is also used to store some temporary state. Those parts of port/state/flags which are useful for applications are exported via the soon-to-be-documented get/set-modes API. -- Holger Kruse [holger--rebol--com]