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Gsm alphabet, 7bit message concatenation #3

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7685213
Use of GSM 7bit alphabet for deconding instead of ASCII alphabet
alexislg2 Sep 10, 2014
ab72093
remove last character in decode 16bits to remove an undefined character
alexislg2 Sep 10, 2014
7cb4b42
Use GSM alphabet when sending 7-bit characters
alexislg2 Sep 10, 2014
92aa73f
modification so that we can concatenate 2 7-bit messages
alexislg2 Sep 10, 2014
7e80bb9
bug fix
alexislg2 Sep 10, 2014
d8da15e
proper 7bit decoding when there is some padding (ie concatenated mess…
alexislg2 Sep 11, 2014
07bbeeb
Use of ESC characters from the GSM alphabet for characters surch as '…
alexislg2 Sep 11, 2014
e49a6ba
Buf fix: good text length.
alexislg2 Sep 11, 2014
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2 changes: 1 addition & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ var pdu = require('pdu');
pdu.generate({
text:'Some text',
receiver:999999999999, //MSISDN
encoding:'16bit' //Or 7bit if you're sending an ascii message.
encoding:'16bit' //Or 7bit if you're sending a message made of GSM standard alphabet characters.
});
```

Expand Down
154 changes: 110 additions & 44 deletions pdu.js
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Original file line number Diff line number Diff line change
@@ -1,5 +1,9 @@
var pduParser = {};

var sevenBitDefault = new Array('@', '£', '$', '¥', 'è', 'é', 'ù', 'ì', 'ò', 'Ç', '\n', 'Ø', 'ø', '\r','Å', 'å','\u0394', '_', '\u03a6', '\u0393', '\u039b', '\u03a9', '\u03a0','\u03a8', '\u03a3', '\u0398', '\u039e','\x1b', 'Æ', 'æ', 'ß', 'É', ' ', '!', '"', '#', '¤', '%', '&', '\'', '(', ')','*', '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7','8', '9', ':', ';', '<', '=', '>', '?', '¡', 'A', 'B', 'C', 'D', 'E','F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S','T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'Ä', 'Ö', 'Ñ', 'Ü', '§', '¿', 'a','b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o','p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'ä', 'ö', 'ñ','ü', 'à');
var sevenBitEsc = new Array('', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '^', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '{', '}', '', '', '', '', '', '\\', '', '', '', '', '', '', '', '', '', '', '', '', '[', '~', ']',
'', '|', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '€', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '');

pduParser.parse = function(pdu) {
//Cursor points to the last octet we've read.
var cursor = 0;
Expand Down Expand Up @@ -76,19 +80,20 @@ pduParser.parse = function(pdu) {
var currentPart = pdu.slice(cursor+12, cursor+14);
}

if(encoding === '16bit')
if(iei == '00')
cursor += (udhLength-2)*4;
else if(iei == '08')
cursor += ((udhLength-2)*4)+2;
if(iei == '00')
cursor += (udhLength-2)*4;
else if(iei == '08')
cursor += ((udhLength-2)*4)+2;
else
cursor += (udhLength-2)*2;
}

if(encoding === '16bit')
var text = pduParser.decode16Bit(pdu.slice(cursor), dataLength);
else if(encoding === '7bit')
var text = pduParser.decode7Bit(pdu.slice(cursor), dataLength);
if (udhi && iei=='00') var text = pduParser.decode7Bit(pdu.slice(cursor), dataLength-7, 1); //If iei ==0, then there is some unpadding to do
else if (udhi && iei=='08') var text = pduParser.decode7Bit(pdu.slice(cursor), dataLength-8); //If no udhi or iei = 08 then no unpadding to do
else var text = pduParser.decode7Bit(pdu.slice(cursor), dataLength);
else if(encoding === '8bit')
var text = ''; //TODO

Expand Down Expand Up @@ -142,7 +147,7 @@ pduParser.detectEncoding = function(dataCodingScheme) {
pduParser.decode16Bit = function(data, length) {
//We are getting ucs2 characters.
var ucs2 = '';
for(var i = 0;i<=data.length;i=i+4) {
for(var i = 0;i<=data.length-1;i=i+4) {
ucs2 += String.fromCharCode("0x"+data[i]+data[i+1]+data[i+2]+data[i+3]);
}

Expand All @@ -160,12 +165,24 @@ pduParser.deSwapNibbles = function(nibbles) {
return out;
}

pduParser.decode7Bit = function(code, count) {
pduParser.decode7Bit = function(code, length, unPadding) {
//We are getting 'septeps'. We should decode them.
var binary = '';
for(var i = 0; i<code.length;i++)
binary += ('0000'+parseInt(code.slice(i,i+1), 16).toString(2)).slice(-4);

//This step is for 'unpadding' the padded data. If it has been encoded with 1 bit padding as it
//happens when the sender used a 7-bit message concatenation (cf http://mobiletidings.com/2009/02/18/combining-sms-messages/)
if (unPadding){
var binary2 = '';
binary = binary + '00000000';
for (var i=0; i<binary.length/8 - 1 ; i++)
{
binary2 += (binary.slice((i+1)*8+(8-unPadding), (i+2)*8) + binary.slice(i*8,i*8+(8-unPadding)));
}
binary = binary2;
}

var bin = Array();
var cursor = 0;
var fromPrevious = '';
Expand All @@ -183,45 +200,96 @@ pduParser.decode7Bit = function(code, count) {
}

var ascii = '';
for(i in bin)
ascii += String.fromCharCode(parseInt(bin[i], 2));

var esc = false; //last character was a ESC
for(var i=0; i<length; i++){
var codeNum = parseInt(bin[i], 2);
if (codeNum == 0x1B){
esc = true;
continue;
}
if (esc)
ascii += sevenBitEsc[codeNum];
else
ascii += sevenBitDefault[codeNum];
esc = false;
}
return ascii;
}

pduParser.encode7Bit = function(ascii) {
//We should create septeps now.
var octets = new Array();
for(var i = 0; i<ascii.length; i++)
octets.push(('0000000'+(ascii.charCodeAt(i).toString(2))).slice(-7));

for(var i in octets) {
var i = parseInt(i);
var freeSpace = 8 - octets[i].length;
pduParser.encode7Bit = function(inTextNumberArray, paddingBits)
{
//as explained here http://mobiletidings.com/2009/07/06/how-to-pack-gsm7-into-septets/
var paddingBits = paddingBits || 0;
var bits = 0;
var out = "";

if(paddingBits)
{
bits = 7 - paddingBits;
var octet = (inTextNumberArray[0] << (7 - bits)) % 256
out += ('00' + octet.toString(16)).slice(-2);
bits++;
}

if(octets[i+1] && freeSpace !== 8) {
octets[i] = octets[i+1].slice(7-freeSpace) + octets[i];
octets[i+1] = octets[i+1].slice(0, 7-freeSpace);
for(var i = 0; i < inTextNumberArray.length; i++ )
{
if( bits == 7 )
{
bits = 0;
continue;
}
var octet = (inTextNumberArray[i] & 0x7f) >> bits;
if( i < inTextNumberArray.length - 1 )
{octet |= (inTextNumberArray[i + 1] << (7 - bits))%256;}
out += ('00' + octet.toString(16)).slice(-2);
bits++;
}
return out;
}

var hex = '';
for(i in octets)
if(octets[i].length > 0)
hex += ('00'+(parseInt(octets[i], 2).toString(16))).slice(-2);
return hex;
pduParser.encode16Bit = function(inTextNumberArray) {
var out = '';
for(var i = 0; i<inTextNumberArray.length;i++) {
out += ('0000'+(inTextNumberArray[i].toString(16))).slice(-4);
}
return out;
}

pduParser.messageToNumberArray = function(message) //sp
{
//7bit GSM encoding according to GSM_03.38 character set http://en.wikipedia.org/wiki/GSM_03.38
res = [];
for (var k=0; k<message.text.length; k++)
{
if (message.encoding == '7bit'){
var character = message.text[k];
for(var i=0;i<sevenBitDefault.length;i++)
{
if(sevenBitDefault[i] == character)
res.push(i);
if (sevenBitEsc[i] == character){
res.push(0x1B); //escape character
res.push(i);
}
}
}
else if (message.encoding == '16bit')
res.push(message.text.charCodeAt(k));
}
return res;
};

//TODO: TP-Validity-Period (Delivery)
pduParser.generate = function(message) {
var pdu = '00';

var parts = 1;
if(message.encoding === '16bit' && message.text.length > 70)
parts = message.text.length / 66;
var inTextNumberArray = this.messageToNumberArray(message);

else if(message.encoding === '7bit' && message.text.length > 160)
parts = message.text.length / 153;
if(message.encoding === '16bit' && inTextNumberArray.length > 70)
parts = inTextNumberArray.length / 66;

else if(message.encoding === '7bit' && inTextNumberArray.length > 160)
parts = inTextNumberArray.length / 153;

parts = Math.ceil(parts);

Expand Down Expand Up @@ -279,7 +347,7 @@ pduParser.generate = function(message) {
else
var length = 153;
}
var text = message.text.slice(i*length, (i*length)+length);
var text = inTextNumberArray.slice(i*length, (i*length)+length);

if(message.encoding === '16bit') {
user_data = pduParser.encode16Bit(text);
Expand All @@ -289,8 +357,14 @@ pduParser.generate = function(message) {
size += 6; //6 is the number of data headers we append.

} else if(message.encoding === '7bit') {
user_data = pduParser.encode7Bit(text);
var size = user_data.length / 2;
if(parts > 1){
user_data = pduParser.encode7Bit(text,1);
var size = 7 + text.length;
}
else {
user_data = pduParser.encode7Bit(text);
var size = text.length;
}
}

pdus[i] += ('00'+parseInt(size).toString(16)).slice(-2);
Expand All @@ -310,14 +384,6 @@ pduParser.generate = function(message) {
}


pduParser.encode16Bit = function(text) {
var out = '';
for(var i = 0; i<text.length;i++) {
out += ('0000'+(parseInt(text.charCodeAt(i), 10).toString(16))).slice(-4);
}
return out;
}

pduParser.swapNibbles = function(nibbles) {
var out = '';
for(var i = 0; i< nibbles.length; i=i+2) {
Expand Down