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authorVadim Yanitskiy <axilirator@gmail.com>2017-08-09 17:38:39 +0600
committerHarald Welte <laforge@gnumonks.org>2018-01-17 10:45:39 +0000
commitfa6c2b9b53d577df916089a26a815e37277eb888 (patch)
tree829521b0b16a3185fee97d720498eee6cf68ae77 /include/osmocom
parent04ee9c04f492d8d1f7800e54b92f20609293ade7 (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
Diffstat (limited to 'include/osmocom')
-rw-r--r--include/osmocom/gsm/gsm0480.h24
1 files changed, 22 insertions, 2 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;
};