From: Holger Hans Peter Freyther zecke@selfish.org
This is required for encoding the SMS header using the alpha numeric rules.
Reviewed-by: Jacob Erlbeck jerlbeck@sysmocom.de --- include/osmocom/gsm/gsm_utils.h | 1 + src/gsm/gsm_utils.c | 10 ++++++++-- src/gsm/libosmogsm.map | 1 + tests/sms/sms_test.c | 15 +++++++++++++++ tests/sms/sms_test.ok | 3 +++ 5 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/include/osmocom/gsm/gsm_utils.h b/include/osmocom/gsm/gsm_utils.h index cf63ea4..a572f50 100644 --- a/include/osmocom/gsm/gsm_utils.h +++ b/include/osmocom/gsm/gsm_utils.h @@ -59,6 +59,7 @@ 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_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_oct(uint8_t *result, const char *data, int *octets_written);
/* the three functions below are helper functions and here for the unit test */ int gsm_septets2octets(uint8_t *result, const uint8_t *rdata, uint8_t septet_len, uint8_t padding); diff --git a/src/gsm/gsm_utils.c b/src/gsm/gsm_utils.c index 9569cf3..54b965e 100644 --- a/src/gsm/gsm_utils.c +++ b/src/gsm/gsm_utils.c @@ -1,6 +1,6 @@ /* * (C) 2008 by Daniel Willmann daniel@totalueberwachung.de - * (C) 2009 by Holger Hans Peter Freyther zecke@selfish.org + * (C) 2009,2013 by Holger Hans Peter Freyther zecke@selfish.org * (C) 2009-2010 by Harald Welte laforge@gnumonks.org * (C) 2010-2012 by Nico Golde nico@ngolde.de * @@ -250,12 +250,18 @@ int gsm_septets2octets(uint8_t *result, const uint8_t *rdata, uint8_t septet_len /* GSM 03.38 6.2.1 Character packing */ int gsm_7bit_encode(uint8_t *result, const char *data) { + int out; + return gsm_7bit_encode_oct(result, data, &out); +} + +int gsm_7bit_encode_oct(uint8_t *result, const char *data, int *octets) +{ int y = 0;
/* prepare for the worst case, every character expanding to two bytes */ uint8_t *rdata = calloc(strlen(data) * 2, sizeof(uint8_t)); y = gsm_septet_encode(rdata, data); - gsm_septets2octets(result, rdata, y, 0); + *octets = gsm_septets2octets(result, rdata, y, 0);
free(rdata);
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map index b2278f1..8a020db 100644 --- a/src/gsm/libosmogsm.map +++ b/src/gsm/libosmogsm.map @@ -134,6 +134,7 @@ gsm48_rr_att_tlvdef; gsm_7bit_decode; gsm_7bit_decode_hdr; gsm_7bit_encode; +gsm_7bit_encode_oct;
gsm_arfcn2band; gsm_arfcn2freq10; diff --git a/tests/sms/sms_test.c b/tests/sms/sms_test.c index 6df4b62..e48f9a3 100644 --- a/tests/sms/sms_test.c +++ b/tests/sms/sms_test.c @@ -209,6 +209,19 @@ static const struct test_case test_decode[] = }, };
+static void test_octet_return() +{ + char out[256]; + int oct, septets; + + printf("Encoding some tests and printing number of septets/octets\n"); + + septets = gsm_7bit_encode_oct((uint8_t *) out, "test1234", &oct); + printf("SEPTETS: %d OCTETS: %d\n", septets, oct); + + printf("Done\n"); +} + int main(int argc, char** argv) { printf("SMS testing\n"); @@ -314,6 +327,8 @@ int main(int argc, char** argv) } }
+ test_octet_return(); + printf("OK\n"); return 0; } diff --git a/tests/sms/sms_test.ok b/tests/sms/sms_test.ok index d0e0983..ce6cb17 100644 --- a/tests/sms/sms_test.ok +++ b/tests/sms/sms_test.ok @@ -1,2 +1,5 @@ SMS testing +Encoding some tests and printing number of septets/octets +SEPTETS: 8 OCTETS: 7 +Done OK
From: Andreas Eversberg jolly@eversberg.eu
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 --- include/osmocom/gsm/gsm_utils.h | 2 ++ src/gsm/gsm0480.c | 10 +++++----- src/gsm/gsm_utils.c | 31 +++++++++++++++++++++++++++++++ src/gsm/libosmogsm.map | 2 ++ tests/ussd/ussd_test.c | 22 ++++++++++++++++++++++ tests/ussd/ussd_test.ok | 21 +++++++++++++++++++++ 6 files changed, 83 insertions(+), 5 deletions(-)
diff --git a/include/osmocom/gsm/gsm_utils.h b/include/osmocom/gsm/gsm_utils.h index a572f50..6cd46e4 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 */ diff --git a/src/gsm/gsm0480.c b/src/gsm/gsm0480.c index b9b3ed9..cc693fe 100644 --- a/src/gsm/gsm0480.c +++ b/src/gsm/gsm0480.c @@ -105,7 +105,7 @@ struct msgb *gsm0480_create_unstructuredSS_Notify(int alertPattern, const char * msgb_put_u8(msg, ASN1_OCTET_STRING_TAG); ussd_len_ptr = msgb_put(msg, 1); data = msgb_put(msg, 0); - len = gsm_7bit_encode(data, text); + gsm_7bit_encode_ussd(data, text, &len); msgb_put(msg, len); ussd_len_ptr[0] = len; /* USSD-String } */ @@ -172,7 +172,7 @@ struct msgb *gsm0480_create_notifySS(const char *text) msgb_put_u8(msg, 0x82); tmp_len = msgb_put(msg, 1); data = msgb_put(msg, 0); - len = gsm_7bit_encode(data, text); + gsm_7bit_encode_ussd(data, text, &len); tmp_len[0] = len; msgb_put(msg, len);
@@ -401,8 +401,8 @@ static int parse_process_uss_req(const uint8_t *uss_req_data, uint16_t length, /* Prevent a mobile-originated buffer-overrun! */ if (num_chars > MAX_LEN_USSD_STRING) num_chars = MAX_LEN_USSD_STRING; - gsm_7bit_decode(req->text, - &(uss_req_data[7]), num_chars); + gsm_7bit_decode_ussd(req->text, + &(uss_req_data[7]), num_chars); rc = 1; } } @@ -423,7 +423,7 @@ struct msgb *gsm0480_create_ussd_resp(uint8_t invoke_id, uint8_t trans_id, const
/* First put the payload text into the message */ ptr8 = msgb_put(msg, 0); - response_len = gsm_7bit_encode(ptr8, text); + gsm_7bit_encode_ussd(ptr8, text, &response_len); msgb_put(msg, response_len);
/* Then wrap it as an Octet String */ diff --git a/src/gsm/gsm_utils.c b/src/gsm/gsm_utils.c index 54b965e..3dd1537 100644 --- a/src/gsm/gsm_utils.c +++ b/src/gsm/gsm_utils.c @@ -172,6 +172,19 @@ int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t septet_l) return gsm_7bit_decode_hdr(text, user_data, septet_l, 0); }
+int gsm_7bit_decode_ussd(char *text, const uint8_t *user_data, uint8_t length) +{ + int i; + + gsm_7bit_decode_hdr(text, user_data, length, 0); + i = strlen(text); + /* remove last <CR>, if it fits up to the end of last octet */ + if (i && (user_data[gsm_get_octet_len(length) - 1] >> 1) == '\r') + text[--i] = '\0'; + + return i; +} + /* GSM 03.38 6.2.1 Prepare character packing */ int gsm_septet_encode(uint8_t *result, const char *data) { @@ -254,6 +267,24 @@ int gsm_7bit_encode(uint8_t *result, const char *data) return gsm_7bit_encode_oct(result, data, &out); }
+int gsm_7bit_encode_ussd(uint8_t *result, const char *data, int *octets) +{ + int y; + + y = gsm_7bit_encode_oct(result, data, octets); + /* if last octet contains only one bit, add <CR> */ + if (((y * 7) & 7) == 1) + result[(*octets) - 1] |= ('\r' << 1); + /* if last character is <CR> and completely fills last octet, add + * another <CR>. */ + if (y && ((y * 7) & 7) == 0 && (result[(*octets) - 1] >> 1) == '\r') { + result[(*octets)++] = '\r'; + y++; + } + + return y; +} + int gsm_7bit_encode_oct(uint8_t *result, const char *data, int *octets) { int y = 0; diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map index 8a020db..1b985e1 100644 --- a/src/gsm/libosmogsm.map +++ b/src/gsm/libosmogsm.map @@ -132,8 +132,10 @@ gsm48_parse_ra; gsm48_rr_att_tlvdef;
gsm_7bit_decode; +gsm_7bit_decode_ussd; gsm_7bit_decode_hdr; gsm_7bit_encode; +gsm_7bit_encode_ussd; gsm_7bit_encode_oct;
gsm_arfcn2band; diff --git a/tests/ussd/ussd_test.c b/tests/ussd/ussd_test.c index 55384f1..d41c141 100644 --- a/tests/ussd/ussd_test.c +++ b/tests/ussd/ussd_test.c @@ -22,6 +22,7 @@ #include <osmocom/core/application.h> #include <osmocom/core/logging.h> #include <osmocom/gsm/gsm0480.h> +#include <osmocom/gsm/gsm_utils.h> #include <stdio.h> #include <stdlib.h> #include <string.h> @@ -68,6 +69,20 @@ static int parse_mangle_ussd(const uint8_t *_data, int len)
struct log_info info = {};
+void gsm_7bit_ussd(char *text) +{ + uint8_t coded[256]; + char decoded[256]; + int y; + + printf("original = %s\n", osmo_hexdump((uint8_t *)text, strlen(text))); + gsm_7bit_encode_ussd(coded, text, &y); + printf("encoded = %s\n", osmo_hexdump(coded, y)); + gsm_7bit_decode_ussd(decoded, coded, y * 8 / 7); + y = strlen(decoded); + printf("decoded = %s\n\n", osmo_hexdump((uint8_t *)decoded, y)); +} + int main(int argc, char **argv) { struct ussd_request req; @@ -93,5 +108,12 @@ int main(int argc, char **argv) printf("Result for %d is %d\n", rc, i); }
+ printf("<CR> case test for 7 bit encode\n"); + gsm_7bit_ussd("01234567"); + gsm_7bit_ussd("0123456"); + gsm_7bit_ussd("01234567\r"); + gsm_7bit_ussd("0123456\r"); + gsm_7bit_ussd("012345\r"); + return 0; } diff --git a/tests/ussd/ussd_test.ok b/tests/ussd/ussd_test.ok index 1b6316e..91f2a31 100644 --- a/tests/ussd/ussd_test.ok +++ b/tests/ussd/ussd_test.ok @@ -51,3 +51,24 @@ Result for 0 is 8 Result for 0 is 7 Result for 0 is 6 Result for 1 is 5 +<CR> case test for 7 bit encode +original = 30 31 32 33 34 35 36 37 +encoded = b0 98 6c 46 ab d9 6e +decoded = 30 31 32 33 34 35 36 37 + +original = 30 31 32 33 34 35 36 +encoded = b0 98 6c 46 ab d9 1a +decoded = 30 31 32 33 34 35 36 + +original = 30 31 32 33 34 35 36 37 0d +encoded = b0 98 6c 46 ab d9 6e 0d +decoded = 30 31 32 33 34 35 36 37 0d + +original = 30 31 32 33 34 35 36 0d +encoded = b0 98 6c 46 ab d9 1a 0d +decoded = 30 31 32 33 34 35 36 0d 0d + +original = 30 31 32 33 34 35 0d +encoded = b0 98 6c 46 ab 35 1a +decoded = 30 31 32 33 34 35 0d +
Renamed gsm_7bit_ussd() to test_7bit_ussd() and extended the function to take the expected binary encoding and eventually added trailing bytes in the re-decoded text as arguments. These are used to check assertions of the right behaviour instead of solely relying on regression data, because the value are determined by the spec and fixed and it is more obvious this way. Especially concerning the case with the duplicated \r which can easily be overlooked when it's only present in the ok file. --- tests/ussd/ussd_test.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/tests/ussd/ussd_test.c b/tests/ussd/ussd_test.c index d41c141..ffb5440 100644 --- a/tests/ussd/ussd_test.c +++ b/tests/ussd/ussd_test.c @@ -69,7 +69,7 @@ static int parse_mangle_ussd(const uint8_t *_data, int len)
struct log_info info = {};
-void gsm_7bit_ussd(char *text) +static void test_7bit_ussd(const char *text, const char *encoded_hex, const char *appended_after_decode) { uint8_t coded[256]; char decoded[256]; @@ -78,9 +78,15 @@ void gsm_7bit_ussd(char *text) printf("original = %s\n", osmo_hexdump((uint8_t *)text, strlen(text))); gsm_7bit_encode_ussd(coded, text, &y); printf("encoded = %s\n", osmo_hexdump(coded, y)); + + OSMO_ASSERT(!strcmp(encoded_hex, osmo_hexdump_nospc(coded, y))); + gsm_7bit_decode_ussd(decoded, coded, y * 8 / 7); y = strlen(decoded); printf("decoded = %s\n\n", osmo_hexdump((uint8_t *)decoded, y)); + + OSMO_ASSERT(!strncmp(text, decoded, strlen (text))); + OSMO_ASSERT(!strcmp(appended_after_decode, decoded + strlen (text))); }
int main(int argc, char **argv) @@ -109,11 +115,12 @@ int main(int argc, char **argv) }
printf("<CR> case test for 7 bit encode\n"); - gsm_7bit_ussd("01234567"); - gsm_7bit_ussd("0123456"); - gsm_7bit_ussd("01234567\r"); - gsm_7bit_ussd("0123456\r"); - gsm_7bit_ussd("012345\r"); + test_7bit_ussd("01234567", "b0986c46abd96e", ""); + test_7bit_ussd("0123456", "b0986c46abd91a", ""); + test_7bit_ussd("01234567\r", "b0986c46abd96e0d", ""); + /* The appended \r is compliant to GSM 03.38 section 6.1.2.3.1: */ + test_7bit_ussd("0123456\r", "b0986c46abd91a0d", "\r"); + test_7bit_ussd("012345\r", "b0986c46ab351a", "");
return 0; }
On Thu, Aug 08, 2013 at 12:38:54PM +0200, Jacob Erlbeck wrote:
all looks good. thank you for the patches. Some cosmetic nitpick.
- OSMO_ASSERT(!strcmp(encoded_hex, osmo_hexdump_nospc(coded, y)));
we tend to use strcmp == 0.
- gsm_7bit_decode_ussd(decoded, coded, y * 8 / 7); y = strlen(decoded); printf("decoded = %s\n\n", osmo_hexdump((uint8_t *)decoded, y));
- OSMO_ASSERT(!strncmp(text, decoded, strlen (text)));
strlen(text) e.g. no space between the opening parethesis
- OSMO_ASSERT(!strcmp(appended_after_decode, decoded + strlen (text)));
I am going to apply all three patches now.
-
Holger Hans Peter Freyther -
Jacob Erlbeck