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-rw-r--r--include/osmocore/gsm_utils.h28
-rw-r--r--src/gsm_utils.c99
-rw-r--r--tests/sms/sms_test.c17
3 files changed, 123 insertions, 21 deletions
diff --git a/include/osmocore/gsm_utils.h b/include/osmocore/gsm_utils.h
index 7dc2388b..64f9edc1 100644
--- a/include/osmocore/gsm_utils.h
+++ b/include/osmocore/gsm_utils.h
@@ -3,6 +3,7 @@
* (C) 2008 by Daniel Willmann <daniel@totalueberwachung.de>
* (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by Nico Golde <nico@ngolde.de>
*
* All Rights Reserved
*
@@ -53,6 +54,33 @@ enum gsm_band {
GSM_BAND_810 = 0x80,
};
+/* ETSI GSM 03.38 6.2.1 and 6.2.1.1 default alphabet
+ * Greek symbols at hex positions 0x10 and 0x12-0x1a
+ * left out as they can't be handled with a char and
+ * since most phones don't display or write these
+ * characters this would only needlessly make the code
+ * more complex
+*/
+unsigned char gsm_7bit_alphabet[] = {
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0a, 0xff, 0xff, 0x0d, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0x20, 0x21, 0x22, 0x23, 0x02, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c,
+ 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
+ 0x3c, 0x3d, 0x3e, 0x3f, 0x00, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a,
+ 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
+ 0x5a, 0x3c, 0x2f, 0x3e, 0x14, 0x11, 0xff, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
+ 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
+ 0x78, 0x79, 0x7a, 0x28, 0x40, 0x29, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0x0c, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5e, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x40, 0xff, 0x01, 0xff,
+ 0x03, 0xff, 0x7b, 0x7d, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5c, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5b, 0x7e, 0x5d, 0xff, 0x7c, 0xff, 0xff, 0xff,
+ 0xff, 0x5b, 0x0e, 0x1c, 0x09, 0xff, 0x1f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x5d,
+ 0xff, 0xff, 0xff, 0xff, 0x5c, 0xff, 0x0b, 0xff, 0xff, 0xff, 0x5e, 0xff, 0xff, 0x1e, 0x7f,
+ 0xff, 0xff, 0xff, 0x7b, 0x0f, 0x1d, 0xff, 0x04, 0x05, 0xff, 0xff, 0x07, 0xff, 0xff, 0xff,
+ 0xff, 0x7d, 0x08, 0xff, 0xff, 0xff, 0x7c, 0xff, 0x0c, 0x06, 0xff, 0xff, 0x7e, 0xff, 0xff
+};
+
const char *gsm_band_name(enum gsm_band band);
enum gsm_band gsm_band_parse(const char *mhz);
diff --git a/src/gsm_utils.c b/src/gsm_utils.c
index dc97ceff..fb69377f 100644
--- a/src/gsm_utils.c
+++ b/src/gsm_utils.c
@@ -2,6 +2,7 @@
* (C) 2008 by Daniel Willmann <daniel@totalueberwachung.de>
* (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2009-2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by Nico Golde <nico@ngolde.de>
*
* All Rights Reserved
*
@@ -34,52 +35,110 @@
#include "../config.h"
-/* GSM 03.38 6.2.1 Charachter packing */
+/* GSM 03.38 6.2.1 Character lookup for decoding */
+static int gsm_septet_lookup(uint8_t ch)
+{
+ int i = 0;
+ for(; i < sizeof(gsm_7bit_alphabet); i++){
+ if(gsm_7bit_alphabet[i] == ch)
+ return i;
+ }
+ return -1;
+}
+
+/* GSM 03.38 6.2.1 Character unpacking */
int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t length)
{
int i = 0;
int l = 0;
+ uint8_t *rtext = calloc(length, sizeof(uint8_t));
+ uint8_t tmp;
- /* FIXME: We need to account for user data headers here */
+ /* FIXME: We need to account for user data headers here */
i += l;
- for (; i < length; i ++)
- *(text ++) =
+ for (; i < length; i ++){
+ rtext[i] =
((user_data[(i * 7 + 7) >> 3] <<
(7 - ((i * 7 + 7) & 7))) |
(user_data[(i * 7) >> 3] >>
((i * 7) & 7))) & 0x7f;
+ }
+ for(i = 0; i < length; i++){
+ /* this is an extension character */
+ if(rtext[i] == 0x1b){
+ tmp = rtext[i+1];
+ *(text++) = gsm_7bit_alphabet[0x7f + tmp];
+ i++;
+ continue;
+ }
+
+ *(text++) = gsm_septet_lookup(rtext[i]);
+ }
+
*text = '\0';
+ free(rtext);
- return i - l;
+ return i;
}
+/* GSM 03.38 6.2.1 Prepare character packing */
+static int gsm_septet_encode(uint8_t *result, const char *data)
+{
+ int i, y = 0;
+ uint8_t ch;
+ for(i = 0; i < strlen(data); i++){
+ ch = data[i];
+ switch(ch){
+ /* fall-through for extension characters */
+ case 0x0c:
+ case 0x5e:
+ case 0x7b:
+ case 0x7d:
+ case 0x5c:
+ case 0x5b:
+ case 0x7e:
+ case 0x5d:
+ case 0x7c:
+ result[y++] = 0x1b;
+ default:
+ result[y] = gsm_7bit_alphabet[ch];
+ break;
+ }
+ y++;
+ }
-/* GSM 03.38 6.2.1 Charachter packing */
+ return y;
+}
+
+/* GSM 03.38 6.2.1 Character packing */
int gsm_7bit_encode(uint8_t *result, const char *data)
{
- int i,j = 0;
- unsigned char ch1, ch2;
+ int i,y,z = 0;
+ /* prepare for the worst case, every character expanding to two bytes */
+ uint8_t *rdata = calloc(strlen(data) * 2, sizeof(uint8_t));
+ uint8_t cb, nb;
int shift = 0;
- for ( i=0; i<strlen(data); i++ ) {
+ y = gsm_septet_encode(rdata, data);
- ch1 = data[i] & 0x7F;
- ch1 = ch1 >> shift;
- ch2 = data[(i+1)] & 0x7F;
- ch2 = ch2 << (7-shift);
+ for(i = 0; i < y; i++) {
+ if(shift == 7 && i + 1 < y){
+ shift = 0;
+ continue;
+ }
- ch1 = ch1 | ch2;
+ cb = (rdata[i] & 0x7f) >> shift;
+ if(i + 1 < y){
+ nb = (rdata[i + 1] & 0x7f) << (7 - shift);
+ cb = cb | nb;
+ }
- result[j++] = ch1;
+ result[z++] = cb;
shift++;
-
- if ((shift == 7) && (i+1<strlen(data))) {
- shift = 0;
- i++;
- }
}
+ free(rdata);
return i;
}
diff --git a/tests/sms/sms_test.c b/tests/sms/sms_test.c
index f5183d54..4daf003a 100644
--- a/tests/sms/sms_test.c
+++ b/tests/sms/sms_test.c
@@ -1,5 +1,6 @@
/*
* (C) 2008 by Daniel Willmann <daniel@totalueberwachung.de>
+ * (C) 2010 by Nico Golde <nico@ngolde.de>
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
@@ -32,7 +33,7 @@ int main(int argc, char** argv)
uint8_t *sms;
uint8_t i;
- /* test 7-bit coding/decoding */
+ /* test 7-bit coding/decoding */
const char *input = "test text";
uint8_t length;
uint8_t coded[256];
@@ -43,5 +44,19 @@ int main(int argc, char** argv)
if (strcmp(result, input) != 0) {
printf("7 Bit coding failed... life sucks\n");
printf("Wanted: '%s' got '%s'\n", input, result);
+ return -1;
}
+
+ memset(coded, 0, sizeof(coded));
+ memset(result, 0, sizeof(coded));
+ input = strdup("!$ a more#^- complicated test@@?_\%! case");
+ length = gsm_7bit_encode(coded, input);
+ gsm_7bit_decode(result, coded, length);
+ if (strcmp(result, input) != 0) {
+ printf("7 Bit coding failed... life sucks\n");
+ printf("Wanted: '%s' got '%s'\n", input, result);
+ return -2;
+ }
+
+ return 0;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 13:08:03 +0000