diff options
| author | Vadim Yanitskiy <axilirator@gmail.com> | 2017-08-09 17:38:39 +0600 |
|---|---|---|
| committer | Harald Welte <laforge@gnumonks.org> | 2018-01-17 10:45:39 +0000 |
| commit | fa6c2b9b53d577df916089a26a815e37277eb888 (patch) | |
| tree | 829521b0b16a3185fee97d720498eee6cf68ae77 | |
| parent | 04ee9c04f492d8d1f7800e54b92f20609293ade7 (diff) | |
gsm0480: fix USSD OCTET STRING length confusion
According to the GSM 04.80 (version 5.0.0) specification Annex A
"Expanded ASN.1 Module "SS-Protocol", the maximum size of a USSD
OCTET STRING is 160 bytes.
Thus according to ETSI TS 123 038 (version 10.0.0) specification
6.1.2.3 "USSD packing of 7 bit characters", in 160 octets, it's
possible to pack (160 * 8) / 7 = 182.8, that is 182 characters.
The remaining 6 bits are set to zero.
This change defines both mentioned values:
- GSM0480_USSD_OCTET_STRING_LEN 160
- GSM0480_USSD_7BIT_STRING_LEN 182
keeping the old MAX_LEN_USSD_STRING 'as is' due to compatibility
reasons. Now the new value is used for ss_request structure, while
old one is still used for deprecated ussd_request structure.
Change-Id: I6dead74f9ecea079752ff2400cdaf7c30187784e
| -rw-r--r-- | include/osmocom/gsm/gsm0480.h | 24 | ||||
| -rw-r--r-- | src/gsm/gsm0480.c | 4 |
2 files changed, 24 insertions, 4 deletions
diff --git a/include/osmocom/gsm/gsm0480.h b/include/osmocom/gsm/gsm0480.h index 672ffe5e..0dfd868f 100644 --- a/include/osmocom/gsm/gsm0480.h +++ b/include/osmocom/gsm/gsm0480.h @@ -7,7 +7,27 @@ #include <osmocom/gsm/protocol/gsm_04_08.h> #include <osmocom/gsm/protocol/gsm_04_80.h> -#define MAX_LEN_USSD_STRING 31 +/** + * According to the GSM 04.80 (version 5.0.0) specification Annex A + * "Expanded ASN.1 Module "SS-Protocol", the maximum size of a USSD + * OCTET STRING field is 160 bytes. + */ +#define GSM0480_USSD_OCTET_STRING_LEN 160 + +/** + * Thus according to ETSI TS 123 038 (version 10.0.0) specification + * 6.1.2.3 "USSD packing of 7 bit characters", in 160 octets, it's + * possible to pack (160 * 8) / 7 = 182.8, that is 182 characters. + * The remaining 6 bits are set to zero. + */ +#define GSM0480_USSD_7BIT_STRING_LEN 182 + +/** + * DEPRECATED: this definition doesn't follow any specification, + * so we only keep it for compatibility reasons. It's strongly + * recommended to use correct definitions above. + */ +#define MAX_LEN_USSD_STRING 31 /* deprecated */ struct ussd_request { @@ -23,7 +43,7 @@ int gsm0480_decode_ussd_request(const struct gsm48_hdr *hdr, uint16_t len, struct ss_request { uint8_t opcode; uint8_t ss_code; - uint8_t ussd_text[MAX_LEN_USSD_STRING + 1]; + uint8_t ussd_text[GSM0480_USSD_OCTET_STRING_LEN]; uint8_t transaction_id; uint8_t invoke_id; }; diff --git a/src/gsm/gsm0480.c b/src/gsm/gsm0480.c index d7c29787..dcf487af 100644 --- a/src/gsm/gsm0480.c +++ b/src/gsm/gsm0480.c @@ -456,8 +456,8 @@ static int parse_process_uss_req(const uint8_t *uss_req_data, uint16_t length, (uss_req_data[5] == ASN1_OCTET_STRING_TAG)) { num_chars = (uss_req_data[6] * 8) / 7; /* Prevent a mobile-originated buffer-overrun! */ - if (num_chars > MAX_LEN_USSD_STRING) - num_chars = MAX_LEN_USSD_STRING; + if (num_chars > GSM0480_USSD_7BIT_STRING_LEN) + num_chars = GSM0480_USSD_7BIT_STRING_LEN; gsm_7bit_decode_n_ussd((char *)req->ussd_text, sizeof(req->ussd_text), &(uss_req_data[7]), num_chars); |