Re: Insertion of character inside a TCP frame

Hi Steph,

here is a little strace output (strace.out) showing that :
- you effectively have 22 bytes
- (length answer) returns 21 because of character C2 which is more than 127
and this mess FORMAT and UTF-8 (see Christophe answer)

To help you see the characters in your answer string, in rbind, replace in
sbcl :
(format t "~A (~A)~%" answer (length answer))
by
(format t "~A (~A)~%" (sb-ext:string-to-octets answer) (length
(sb-ext:string-to-octets answer)))

it prints :
#(0 0 0 21 194 128 0 0 1 0 0 0 0 0 0 0 1 83 77 80 80 0) (22)

I would be glad to see your final solution,

Regards,
Jérôme.

Le mar. 16 juil. 2024 à 10:00, Marco Antoniotti <[email protected]>
a écrit :

> Hi Stephane
>
> you may want to have a look at *babel* and maybe *cl-pack* for encoding
> and decoding.  I am sure there are others around and some of them may
> suffer from some bit rot.
>
> All the best
>
> Marco
>
> On Tue, Jul 16, 2024 at 9:49 AM Christophe Rhodes <[email protected]>
> wrote:
>
>> "steph.tougard via Sbcl-help" <[email protected]> writes:
>>
>> > For those who don't know, SMPP is a binary protocol over TCP to send
>> > SMS. Unlike SMPP or HTTP, each frame is sent or received between the
>>
>> SMPP is a binary protocol, but your Lisp code uses characters and
>> strings.  This means that there will be an encoding step on the Lisp
>> side, to convert from characters to binary.
>>
>> In most lisps nowadays, the default encoding scheme is probably utf-8,
>> which encodes the ASCII repertoire (the first 128 characters of Unicode)
>> as single bytes, but uses multiple bytes for all other characters.
>>
>> I would guess that the string that you are attempting to send contains a
>> character with char-code greater than 127, and that your stream is set
>> up to convert characters using utf-8.
>>
>> You are using usocket, which does not allow users to specify external
>> formats directly.  You could try setting
>> sb-ext:*default-external-format* to :latin-1 before starting your
>> server, or you could send binary (rather than string) data to your
>> socket, performing the character to binary conversion yourself rather
>> than making it implicit.
>>
>> Christophe
>>
>>
>> _______________________________________________
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>> [email protected]
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>>
>
>
> --
> Marco Antoniotti, Professor                   tel. +39 - 02 64 48 79 01
> DISCo, University of Milan-Bicocca U14 2043   http://dcb.disco.unimib.it
> Viale Sarca 336
> I-20126 Milan (MI) ITALY
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