[Haskell-cafe] Data.Binary and little endian encoding

[David Leimbach]

On Thu, May 14, 2009 at 9:10 PM, David Leimbach <leimy2k at gmail.com> wrote:

>
>
> On Thu, May 14, 2009 at 8:57 PM, David Leimbach <leimy2k at gmail.com> wrote:
>
>>
>>
>> On Thu, May 14, 2009 at 8:54 PM, Don Stewart <dons at galois.com> wrote:
>>
>>> > I'm speaking specifically of the encode/decode functions.  I have no
>>> idea how
>>> > they're implemented.
>>> >
>>> > Are you saying that encode is doing something really simple and the
>>> default
>>> > encodings for things just happen to be big endian?  If so, then I
>>> understand
>>> > the pain.... but it still means I have to roll my own :-)  I guess if
>>> one must
>>> > choose, big endian kind of makes sense, except that the whole world is
>>> little
>>> > endian now, except for networks :-)  (No one *really* cares about
>>> anything but
>>> > x86 anyway these days right?)
>>>
>>> Oh, 'encode' has type:
>>>
>>>    encode :: Binary a => a -> ByteString
>>>
>>> it just encodes with the default instances, which are all network order:
>>>
>>>    http://en.wikipedia.org/wiki/Endianness#Endianness_in_networking
>>>
>>
>> Yeah I understand that Big Endian == Network Byte Order... which would be
>> true, if I wasn't talking about Plan 9's 9P protocol which specifies little
>> endian bytes on the wire (as far as I can tell anyway from the man page).
>>
>> Dave
>>
>
> FYI here's what I've ended up trying to write to negotiate the "version" of
> a 9p server:
>
> main = withSocketsDo $
>        do
>           ainfo <- getAddrInfo Nothing (Just "127.0.0.1") (Just "6872")  --
> hardcoded for now, it's an IRC filesystem server
>           let a = head ainfo
>           sock <- socket AF_INET Stream defaultProtocol
>           connect sock (addrAddress a)
>           sendAll sock $ (toLazyByteString (putWord32le (fromIntegral (16
> ::Int32))))
>           sendAll sock $ (encode (100 ::Int8))
>           sendAll sock $ (toLazyByteString (putWord32le (fromIntegral (1024
> ::Int32))))
>           sendAll sock $ (encode (C.pack "9P2000"))
>
>

I totally forgot the tag part of 9p.... ugh.  I think I should probably just
go to bed now.


>
> I feel like I should use wireshark or something to watch the bytes :-)  I'm
> not feeling very sure about this.
>
>
>>
>>>
>>> -- Don
>>>
>>
>>
>
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