101 lines
3.1 KiB
Java
101 lines
3.1 KiB
Java
package zutil.parser;
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import zutil.parser.DataNode.DataType;
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/**
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* http://wiki.theory.org/BitTorrentSpecification
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* @author Ziver
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*
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*/
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public class BEncodedParser {
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/**
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* Returns the representation of the data in the BEncoded string
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*
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* @param data The data to be decoded
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* @return
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*/
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public static DataNode parse(String data){
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return decode_BEncoded(new StringBuffer(data));
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}
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/**
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* Returns the representation of the data in the BEncoded string
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*
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* @param data The data to be decoded
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* @param index The index in data to start from
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* @return
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*/
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private static DataNode decode_BEncoded(StringBuffer data){
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String tmp;
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char c = ' ';
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switch (data.charAt(0)) {
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/**
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* Integers are prefixed with an i and terminated by an e. For
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* example, 123 would bEcode to i123e, -3272002 would bEncode to
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* i-3272002e.
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*/
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case 'i':
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//System.out.println("Found Integer at "+index);
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data.deleteCharAt(0);
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tmp = data.substring(0, data.indexOf("e"));
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data.delete(0, tmp.length() + 1);
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//System.out.println(tmp);
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return new DataNode( new Long(tmp));
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/**
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* Lists are prefixed with a l and terminated by an e. The list
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* should contain a series of bEncoded elements. For example, the
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* list of strings ["Monduna", "Bit", "Torrents"] would bEncode to
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* l7:Monduna3:Bit8:Torrentse. The list [1, "Monduna", 3, ["Sub", "List"]]
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* would bEncode to li1e7:Mondunai3el3:Sub4:Listee
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*/
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case 'l':
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//System.out.println("Found List at "+index);
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data.deleteCharAt(0);
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DataNode list = new DataNode( DataType.List );
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c = data.charAt(0);
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while(c != 'e'){
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list.add( decode_BEncoded(data) );
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c = data.charAt(0);
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}
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data.deleteCharAt(0);
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//MultiPrintStream.out.dump(list);
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if(list.size() == 1) return list.get(0);
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else return list;
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/**
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* Dictionaries are prefixed with a d and terminated by an e. They
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* are similar to list, except that items are in key value pairs. The
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* dictionary {"key":"value", "Monduna":"com", "bit":"Torrents", "number":7}
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* would bEncode to d3:key5:value7:Monduna3:com3:bit:8:Torrents6:numberi7ee
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*/
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case 'd':
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//System.out.println("Found Dictionary at "+index);
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data.deleteCharAt(0);
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DataNode map = new DataNode( DataType.Map );
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c = data.charAt(0);
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while(c != 'e'){
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DataNode tmp2 = decode_BEncoded(data);
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map.set(tmp2.getString(), decode_BEncoded(data));
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c = data.charAt(0);
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}
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data.deleteCharAt(0);
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//MultiPrintStream.out.dump(map);
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return map;
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/**
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* Strings are prefixed with their length followed by a colon.
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* For example, "Monduna" would bEncode to 7:Monduna and "BitTorrents"
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* would bEncode to 11:BitTorrents.
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*/
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default:
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//System.out.println("Found String at "+index);
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tmp = data.substring(0, data.indexOf(":"));
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int length = Integer.parseInt(tmp);
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data.delete(0, tmp.length()+1);
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String ret = data.substring(0, length);
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data.delete(0, length);
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//System.out.println(data.substring(i, i+length));
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return new DataNode( ret );
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}
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}
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}
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