From 9a35914bc1c7b78d13ec400350eb8639e8125a0e Mon Sep 17 00:00:00 2001
From: Dennis Wehrle <openbsc@wehrle.it>
Date: Tue, 22 Mar 2011 18:25:53 +0100
Subject: [PATCH] SMS-fix: due to a misuse of user_data_len the sms where cropped (on vty) and wrongly stored on the database.
 Therefore two new functions was created: uint8_t gsm_get_octet_len(const uint8_t sept_len) and uint8_t gsm_get_septet_len(const char *text)

---
 include/osmocore/gsm_utils.h |    3 ++
 src/gsm_utils.c              |   54 ++++++++++++++++++++++++++++++++++++++---
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/include/osmocore/gsm_utils.h b/include/osmocore/gsm_utils.h
index 0aadd2e..a47ce7b 100644
--- a/include/osmocore/gsm_utils.h
+++ b/include/osmocore/gsm_utils.h
@@ -59,6 +59,9 @@ 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_encode(uint8_t *result, const char *data);
 
+uint8_t gsm_get_octet_len(const uint8_t sept_len);
+uint8_t gsm_get_septet_len(const char *text);
+
 int ms_pwr_ctl_lvl(enum gsm_band band, unsigned int dbm);
 int ms_pwr_dbm(enum gsm_band band, uint8_t lvl);
 
diff --git a/src/gsm_utils.c b/src/gsm_utils.c
index 31e3cd6..faac7cf 100644
--- a/src/gsm_utils.c
+++ b/src/gsm_utils.c
@@ -73,17 +73,52 @@ static int gsm_septet_lookup(uint8_t ch)
 	return -1;
 }
 
+/* Warning, user_data_len indicates the amount of septets (characters), we need amount of octets occupied */
+/* compute the number of octets: */
+/* #octets = (#septets * 7 bit) / 8 bit */
+/* e.g. 47 non-extension characters needs 329 bits / 8 bit = 41,125 octets => we need 42 octets for 47 characters */
+uint8_t gsm_get_octet_len(const uint8_t sept_len){
+	int octet_len = (sept_len * 7) / 8;
+	if ((sept_len * 7) % 8 != 0)
+		octet_len++;
+
+	return octet_len;
+}
+
+
+/* Get number of septets. Each extension character has to be count twice, because they need 2 septets*/
+uint8_t gsm_get_septet_len(const char *text){
+	uint8_t septet_len = strlen(text);
+	int i;
+	for(i = 0; i < strlen(text); i++){
+		switch(text[i]){
+		case 0x0c:
+		case 0x5e:
+		case 0x7b:
+		case 0x7d:
+		case 0x5c:
+		case 0x5b:
+		case 0x7e:
+		case 0x5d:
+		case 0x7c:
+			septet_len++;
+		default:
+			continue;
+		}
+	}
+	return septet_len;
+}
+
 /* 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;
-	int septet_l = (length * 8) / 7;
+
+	int septet_l = length;
 	uint8_t *rtext = calloc(septet_l, sizeof(uint8_t));
 	uint8_t tmp;
 
 	/* FIXME: We need to account for user data headers here */
-	i += l;
 	for (; i < septet_l; i++){
 		rtext[i] =
 			((user_data[(i * 7 + 7) >> 3] <<
@@ -155,6 +190,12 @@ int gsm_7bit_encode(uint8_t *result, const char *data)
 			shift = 0;
 			continue;
 		}
+		/* special end case. This is necessary if the last septet fits into the previous octet. */
+		/* E.g. 48 non-extension characters: ....ag ( a = 1100001, g = 1100111) */
+		/* result[40] = 100001 XX */
+		/* result[41] = 1100111 1 */
+		if(shift == 7 && i + 1 == y)
+			break;
 
 		cb = (rdata[i] & 0x7f) >> shift;
 		if(i + 1 < y){
@@ -168,7 +209,12 @@ int gsm_7bit_encode(uint8_t *result, const char *data)
 	}
 
 	free(rdata);
-	return z;
+
+	/* we don't care about the number of octets, because they are not unique. E.g.: */
+	/* 1.) 46 non-extension characters + 1 extension character => (46 * 7 bit + (1 * (2 * 7 bit))) / 8 bit =  42 octets */
+	/* 2.) 47 non-extension characters => (47 * 7 bit) / 8 bit = 41,125 = 42 octets */
+	/* 3.) 48 non-extension characters => (48 * 7 bit) / 8 bit = 42 octects */
+	return y;
 }
 
 /* determine power control level for given dBm value, as indicated
-- 
1.7.1