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authorAndreas Eversberg <jolly@eversberg.eu>2013-08-08 12:38:53 +0200
committerHolger Hans Peter Freyther <holger@moiji-mobile.com>2013-08-08 14:27:13 +0200
commit9597555a362cd28c02e9bbfe4f55c4b90ecdfa34 (patch)
tree819721bf3ee366ff6a333da64cb646519e1e0a2c /include
parent6bfa7445fca074fdf94707681d93e92ec0993bbd (diff)
Add special 7-bit encoding and decoding functions for USSD coding
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>
Diffstat (limited to 'include')
-rw-r--r--include/osmocom/gsm/gsm_utils.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/osmocom/gsm/gsm_utils.h b/include/osmocom/gsm/gsm_utils.h
index a572f504..6cd46e45 100644
--- a/include/osmocom/gsm/gsm_utils.h
+++ b/include/osmocom/gsm/gsm_utils.h
@@ -57,8 +57,10 @@ const char *gsm_band_name(enum gsm_band band);
enum gsm_band gsm_band_parse(const char *mhz);
int gsm_7bit_decode(char *decoded, const uint8_t *user_data, uint8_t length);
+int gsm_7bit_decode_ussd(char *decoded, const uint8_t *user_data, uint8_t length);
int gsm_7bit_decode_hdr(char *decoded, const uint8_t *user_data, uint8_t length, uint8_t ud_hdr_ind);
int gsm_7bit_encode(uint8_t *result, const char *data);
+int gsm_7bit_encode_ussd(uint8_t *result, const char *data, int *octets_written);
int gsm_7bit_encode_oct(uint8_t *result, const char *data, int *octets_written);
/* the three functions below are helper functions and here for the unit test */