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[PATCH] rewritten gsm 7 bit encoding
by Nico Golde 09 Jul '10

09 Jul '10

Hi, I've rewritten the GSM 7 bit default encoding as the current implementation results in wrong encoding for certain characters, e.g. '@'. The septet packing lacked the lookup and this only worked for characters that had a 1-1 mapping between their ascii value and the default alphabet table. I introduced a lookup table and now do the character translation before packing the data. Patch is attached. I guess the decoding needs to be rewritten as well and I may provide a patch for that in the future as well. For now the encoding produced enough headaches for me :) I adjusted the copyright stanza in these files but I'm not completely sure if this is appropriate or not, so feel free to remove, I won't be offended :) Cheers Nico

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[PATCH] * rewrite gsm_7bit_encode() based on a lookup table as the previous code produced wrong encodings for certain characters.
by Nico Golde 08 Jul '10

08 Jul '10

--- include/osmocore/gsm_utils.h | 28 ++++++++++++++++++ src/gsm_utils.c | 64 ++++++++++++++++++++++++++++++++---------- 2 files changed, 77 insertions(+), 15 deletions(-) diff --git a/include/osmocore/gsm_utils.h b/include/osmocore/gsm_utils.h index 7dc2388..661846a 100644 --- a/include/osmocore/gsm_utils.h +++ b/include/osmocore/gsm_utils.h @@ -3,6 +3,7 @@ * (C) 2008 by Daniel Willmann <daniel(a)totalueberwachung.de> * (C) 2009 by Holger Hans Peter Freyther <zecke(a)selfish.org> * (C) 2009-2010 by Harald Welte <laforge(a)gnumonks.org> + * (C) 2010 by Nico Golde <nico(a)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, 0x0a, 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, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01, 0x24, + 0x03, 0xff, 0x5f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x60, 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 dc97cef..ce5cefd 100644 --- a/src/gsm_utils.c +++ b/src/gsm_utils.c @@ -2,6 +2,7 @@ * (C) 2008 by Daniel Willmann <daniel(a)totalueberwachung.de> * (C) 2009 by Holger Hans Peter Freyther <zecke(a)selfish.org> * (C) 2009-2010 by Harald Welte <laforge(a)gnumonks.org> + * (C) 2010 by Nico Golde <nico(a)ngolde.de> * * All Rights Reserved * @@ -53,33 +54,66 @@ int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t length) return i - l; } +/* 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){ + case 0x0c: + case 0x5e: + case 0x7b: + case 0x7d: + case 0x5c: + case 0x5b: + case 0x7e: + case 0x5d: + case 0x7c: + result[y] = 0x1b; + result[y + 1] = gsm_7bit_alphabet[ch]; + y++; + break; + 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; } -- 1.7.1 --liOOAslEiF7prFVr--

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[PATCH] * rewrite gsm_7bit_encode() based on a lookup table as the previous code produced wrong encodings for certain characters.
by Nico Golde 08 Jul '10

08 Jul '10

--- include/osmocore/gsm_utils.h | 28 ++++++++++++++++++ src/gsm_utils.c | 64 ++++++++++++++++++++++++++++++++---------- 2 files changed, 77 insertions(+), 15 deletions(-) diff --git a/include/osmocore/gsm_utils.h b/include/osmocore/gsm_utils.h index 7dc2388..661846a 100644 --- a/include/osmocore/gsm_utils.h +++ b/include/osmocore/gsm_utils.h @@ -3,6 +3,7 @@ * (C) 2008 by Daniel Willmann <daniel(a)totalueberwachung.de> * (C) 2009 by Holger Hans Peter Freyther <zecke(a)selfish.org> * (C) 2009-2010 by Harald Welte <laforge(a)gnumonks.org> + * (C) 2010 by Nico Golde <nico(a)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, 0x0a, 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, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01, 0x24, + 0x03, 0xff, 0x5f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x60, 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 dc97cef..f0b031d 100644 --- a/src/gsm_utils.c +++ b/src/gsm_utils.c @@ -2,6 +2,7 @@ * (C) 2008 by Daniel Willmann <daniel(a)totalueberwachung.de> * (C) 2009 by Holger Hans Peter Freyther <zecke(a)selfish.org> * (C) 2009-2010 by Harald Welte <laforge(a)gnumonks.org> + * (C) 2010 by Nico Golde <nico(a)ngolde.de> * * All Rights Reserved * @@ -53,33 +54,66 @@ int gsm_7bit_decode(char *text, const uint8_t *user_data, uint8_t length) return i - l; } +/* 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){ + case 0x0c: + case 0x5e: + case 0x7b: + case 0x7d: + case 0x5c: + case 0x5b: + case 0x7e: + case 0x5d: + case 0x7c: + result[y] = 0x1b; + result[y + 1] = gsm_7bit_alphabet[ch]; + y++; + break; + 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; } -- 1.7.1 --fUYQa+Pmc3FrFX/N--

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Re: Working GSM1800 config for latest OpenBSC
by Stephen Mortimer 07 Jul '10

07 Jul '10

Thanks Sylvian, Removing the E1 config lines did the trick. Regards, Steve

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Fuzzing your GSM phone with OpenBSC and Scapy
by Stephen Mortimer 07 Jul '10

07 Jul '10

Hi, Is there a version of Scapy with the GSM protocol layers that I can use with the ipaccess-proxy, as discussed in Harold Welte's presentation? Many thanks, Steve

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nanobts sends no BCCH
by Nordin 07 Jul '10

07 Jul '10

Hi guys, Today I git-cloned the latest version opnbsc/libosmocore and built it successfully. But when running the nanoBTS900, no BCCH is sent, just the carrier signal. I can confirm this, because I've two nanoBTSs, one 900 and the other 1800, the 1800 version works well. With a special gsm module (Telit), I can perform a scan for the available BCCHs in the environment. Anyone recognize this?

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LCR crashes. Please help me!
by Luca Bertoncello 07 Jul '10

07 Jul '10

Hi, List! I'm trying to get OpenBSC working with Asterisk. I have a working configuration of Asterisk, and a working configuration of OpenBSC. I use a nanoBTS DSC1800. The O.S. is Debian lenny and I have a Cologne Chip Designs GmbH ISDN network Controller [HFC-E1] ISDN card. In my interface.conf I just have: [GSM] gsm-bs nt layer1hold no layer2hold no tones yes earlyb no channel-in free channel-out any nodtmf My gsm.conf: interface-bsc mISDN_l1loop.1 interface-lcr mISDN_l1loop.2 debug DRLL:DCC:DMM:DRR:DRSL:DNM:DSMS:DMNCC:DMNSMS:DPAG:DMUX:DMEAS config /home/lucabert/bscAsterisk/lucabertBSC.cfg hlr /home/lucabert/bscAsterisk/hlr.sqlite3 In my options.conf I have a line: gsm and in my routing.conf I have this line by [main]: interface=GSM : remote application=asterisk context=btsctrl Now I start LCR (as root): /usr/local/sbin/lcr start It starts and wait until the nanoBTS log in. Then, when I try to use the net with my mobile, LCR crashes. I generated a core file. With gdb I see: Program terminated with signal 11, Segmentation fault. [New process 4026] [New process 4029] #0 0x0805b009 in gsm0408_rcvmsg (msg=0x864ffb8, link_id=0 '\0') at openbsc/src/bsc_api.c:111 111 rc = api->compl_l3(lchan->conn, msg, 0); The problem seems to be the variable api, which is NULL. (gdb) print api $1 = (struct bsc_api *) 0x0 Can someone help me? I use OpenBSC 0.9.0.967-02d3 and LCR 1.7 (both downloaded yesterday with git clone). Thanks a lot for your help -- _______________________________________________________________________ Luca Bertoncello Entwicklung Mail: bertoncello(a)netzing.de NETZING Solutions AG Tel.: 0351/41381 - 0 Kesselsdorfer Str. 216, 01169 Dresden Fax: 0351/41381 - 12 HRB 18926 / Ust.ID DE211326547 Mail: netzing.ag(a)netzing.de _______________________________________________________________________

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Re: Help by connecting OpenBSC with Asterisk
by Sylvain Munaut 05 Jul '10

05 Jul '10

> As I don't have access to a nanoBTS I never tried it, but you could take a > look at Sylvain's chan_openbsc for Asterisk > (http://github.com/smunaut/ast_chan_openbsc) Yeah, that probably doesn't work anymore. Yet another thing I must finish. But that's pretty low on my list ... Sylvain

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Can't change nanoBTS id.
by Nordin 05 Jul '10

05 Jul '10

Hello guys, I want to change a nanoBTS's id, so I can control two BTSs each as a seperate BTS (not as a seperate TRX). But this is what I get: $ ./ipaccess-config -u 1801/1/0 10.100.2.27 ipaccess-config (C) 2009-2010 by Harald Welte and others This is FREE SOFTWARE with ABSOLUTELY NO WARRANTY Trying to connect to ip.access BTS ... <0005> abis_nm.c:518 OC=SITE-MANAGER(00) INST=(ff,ff,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) <0005> abis_nm.c:518 OC=BTS(01) INST=(00,ff,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=BASEBAND-TRANSCEIVER(04) INST=(00,00,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked OML link established using TRX 0 setting Unit ID to '1801/1/0' <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,00) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,01) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,02) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,03) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,04) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,05) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,06) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=CHANNEL(03) INST=(00,00,07) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=RADIO-CARRIER(02) INST=(00,00,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=GPRS-NSE(f0) INST=(00,ff,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=GPRS-CELL(f1) INST=(00,00,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=GPRS-NSVC(f2) INST=(00,00,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=GPRS-NSVC(f2) INST=(00,01,ff) STATE CHG: OP_STATE=Disabled AVAIL=Not installed(07) ADM=Locked <0005> abis_nm.c:518 OC=BASEBAND-TRANSCEIVER(04) INST=(00,00,ff) IPACCESS(0xf1): <0005> abis_nm.c:2757 SET NVATTR NACK CAUSE=Parameter value outside permitted range Failure to set attribute. This seems fatal Is this familiar to you? Thank you.

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Help by connecting OpenBSC with Asterisk
by Luca Bertoncello 05 Jul '10

05 Jul '10

Hi, List! I have now to connect OpenBSC with Asterisk, in order to use a VoIP-phone to call mobiles (and viceversa). I found this HowTo: http://openbsc.osmocom.org/trac/wiki/OpenBSC_LCR Since I don't know Asterisk I'm not sure if it is what I really need... In the HowTo 2 ISDN-Cards are used. Need I really these? I'm using a nanoBTS (accessed over Ethernet), so I think I don't need the Cologne Chips E1 PCI card. Is it right? Then, at least as first step, I don't want to connect my Asterisk with the rest of the world. I really want to create my own test-network with a VoiIP-phone and a couple of mobiles. Do I really need a ISDN-card? And last, but not least, (as I said, I don't know Asterisk!!), how can I decide, that a number I choose from mobile or VoiIP-phone is a mobile or a VoiIP-phone? Maybe there is a running configuration of Asterisk I can use as example? Thanks a lot for your help! -- _______________________________________________________________________ Luca Bertoncello Entwicklung Mail: bertoncello(a)netzing.de NETZING Solutions AG Tel.: 0351/41381 - 0 Kesselsdorfer Str. 216, 01169 Dresden Fax: 0351/41381 - 12 HRB 18926 / Ust.ID DE211326547 Mail: netzing.ag(a)netzing.de _______________________________________________________________________

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