Handling 7-bit coding is a little different for USSD, as TS 03.38
states:
To avoid the situation where the receiving entity confuses 7 binary
zero pad bits as the @ character, the carriage return or <CR>
character shall be used for padding in this situation [...].
If <CR> is intended to be the last character and the message
(including the wanted <CR>) ends on an octet boundary, then another
<CR> must be added together with a padding bit 0. The receiving entity
will perform the carriage return function twice, but this will not
result in misoperation as the definition of <CR> [...] is identical to
the definition of <CR><CR>.
The receiving entity shall remove the final <CR> character where the
message ends on an octet boundary with <CR> as the last character.
Jacob has verified the fix with fakeBTS and the wireshark dissector.
Fixes: OW#947
Reviewed-by: Jacob Erlbeck <jerlbeck@sysmocom.de>
This reverts commit f996b05dbd
and 2b0cac4ef8. A detailed
explanation can be found here:
http://lists.osmocom.org/pipermail/openbsc/2013-July/004737.html
The short description is that:
1.) The API should return (as out parameter) the number of
octets used.
2.) The handling for the <CR> encoding only applies to USSD
and it is incomplete. On top of that it broke the SMS test.
To avoid the situation where the receiving entity confuses 7 binary zero pad
bits as the @ character, the carriage return or <CR> character shall be used
for padding in this situation.
The comment explains why we don't care about the content of z,
stop storing it.
gsm_utils.c: In function 'gsm_7bit_encode':
gsm_utils.c:253:13: warning: variable 'z' set but not used [-Wunused-but-set-variable]
Additionally it wasn't possible to send concatenated sms from the vty.
To send multiple sms, it is necessary to use padding bits and add a user_data_header.
Therefore the gsm_7bit_encode function was splitted to gsm_7bit_encode and gsm_septets2octets.
gsm_septets2octets: this is the old gsm_7bit_encode function + additional padding parameter
Additionally the gsm_7bit_decode function was modified to take account for the user_data_header.
With the new gsm_get_octet_len function you can get the octet length for a given septet length.
I also added several sms tests.
This patch moves all GSM-specific definitions to include/osmocom/gsm.
Moreover, the headers in include/osmocore/ have been moved to
include/osmocom/core.
This has been proposed by Harald Welte and Sylvain Munaunt.
Tested with `make distcheck'.
Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>
libosmogsm which is provided by libosmocore.
I have also moved generate_backtrace() to backtrace.c instead
of gsm_utils.c, otherwise the timer and msgfile tests depend on
libosmogsm.
Signed-off-by: Pablo Neira Ayuso <pablo@gnumonks.org>