Re: [PATCH] Parse +CUSD responses.

[Denis Kenzior <denkenz@gmail.com>]

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Hi Andrew,

> USSD.Initiate still returns a string, this may be wrong because
> when the network returns data coded in 8-bits we have no information
> on the character set used, everything is "user-specified" for the
> 8-bit coding in the 23.038 and technically we should return an array

Right now we should simply ignore 8bit data and return an error.

> I removed the "TODO: be able to send UCS2 string" because the string
> we send is first checked to be a valid USSD string so we already know
> it can be encoded with GSM 7-bits.

Actually valid_ussd_string will accept just about everything.

> +	/* All 7-bit coding schemes - there's no need to distinguish
> +	 * between the different schemes because the modem is tasked
> +	 * with presenting us with only raw 7-bit characters.
> +	 */
> +	if ((dcs & 0xf0) == 0x00 || dcs == 0x10 || (dcs & 0xf0) == 0x20 ||
> +			(dcs & 0xf0) == 0x30 || (dcs & 0xcc) == 0x40 ||
> +			(dcs & 0xfc) == 0x90 || (dcs & 0xf4) == 0xf0)
> +		converted = convert_gsm_to_utf8(content, length,
> +						NULL, NULL, 0);
> +

What about the evil set of DCSes which indicate a ISO639 2 character code 
preceding the message?

> -	sprintf(buf, "AT+CUSD=1,\"%*s\",%d", (int) written, converted, dcs);
> +	len = sprintf(buf, "AT+CUSD=1,\"");
> +	for (i = 0; i < written; i ++)
> +		len += sprintf(buf + len, "%02hhx", converted[i]);
> +	sprintf(buf + len, "\",%d", dcs);
>

So this part concerns me, see below.

> +	dump_response("cssu_notify", TRUE, result);

cssd_notify :)

> +
> +	g_at_chat_send(chat, "AT+CSCS=\"HEX\"", NULL, NULL, NULL, NULL);

This part of 27.007 is utterly and completely broken.  We have to be extra 
careful whenever we mess with CSCS.  Does this have any unfortunate side 
effects, in particular with +COPS, +CPUC, etc?  Also note that since we change 
the CSCS during phonebook import, any USSDs sent/received during this time 
won't actually work properly :)

Regards,
-Denis