IRC Praser

IRC stands for Internet Relay Chat.There are many irc clients/bots out there and the heart of them is the irc parser which works according to the irc protocol.This Java program is a simple one,which reads raw irc log file “raw.log” and parses each line of command and place its parts in the IrcMsg class which is like a nested structure.

/*
 * IRC Parser by Warrior in compliance with RFC1459.
 * If you plan to use this source code or part of it then you will have to
 * agree to the following License.
 * License:- http://creativecommons.org/licenses/by/2.5/in/
 * You will have to give the author credit on using part or full of this
 * source code.
 */

import java.io.*;

class IRC{
 static IrcMsg irc_msg=new IrcMsg();
 static IrcParser irc_parser=new IrcParser(irc_msg);

 public static void  display(){
 System.out.print(irc_msg.prefix.nick+" "+irc_msg.cmd.num_reply+":"
 +irc_msg.cmd.command+"\n");

 for(int i=0;i<irc_msg.param_cnt;i++)
 System.out.print(irc_msg.params[i]);

 System.out.print("\nUser:"+irc_msg.prefix.user+" Host:"+irc_msg.prefix.host+"\n");
 }

 public static void main(String args[])throws IOException{
 GetData lget=new GetData("raw.log");
 String line;
 while((line=lget.getline())!=null){
 //System.out.println("Raw:-"+line);
 irc_parser.irc_scan(line);
 display();
 }
 }
}

//You can substitute this class to get data from irc server
class GetData{
 String log;
 FileReader file;
 BufferedReader fin;
 GetData(String name){
 log=name;
 try{
 file=new FileReader(log);
 fin=new BufferedReader(file);
 }catch(FileNotFoundException e){
 System.out.println("File not found:"+e);
 System.exit(1);
 }
 }

 String getline()throws IOException{
 char c;
 String line;
 line=fin.readLine();
 if(line==null)
 fin.close();
 return line;
 }
}

//Idea is to create a skeleton like nested structures
class IrcMsg{
 static Prefix  prefix;
 static Command cmd;

 IrcMsg()
 {
 prefix=new Prefix();
 cmd=new Command();
 }

 class Prefix{
 String nick;
 String user;
 String host;
 }

 class Command{
 String command;
 int num_reply;
 }

 static String params[]=new String[15];
 static int param_cnt;
}

class IrcParser{
 static IrcMsg irc_msg;

 IrcParser(IrcMsg irc_msg){
 this.irc_msg=irc_msg;
 }

 boolean irc_number(char c){
 return (c>='0' && c<='9');
 }

 boolean irc_letter(char c){
 return ((c>='A' && c<='Z')||(c>='a' && c<='z'));
 }

 boolean irc_trail(char c){
 return (c==':');
 }

 boolean irc_special(char c){
 return ("-[]\\`^{}".indexOf(c)!=-1);
 }

 boolean irc_user(char c){
 return ("@\r\n".indexOf(c)==-1);
 }

 boolean irc_host(char c){
 return (irc_letter(c) || irc_number(c) || c=='.' || c=='-');
 }

 boolean irc_space(char c){
 return (c==' ');
 }

 boolean irc_eol(char c){ //irc commands are generally terminated by CRLF
 return (c=='\r' || c=='\n');
 }

 void    zeromemory(){
 for(int i=0;i<15;i++)
 irc_msg.params[i]="";
 irc_msg.param_cnt=0;
 irc_msg.prefix.nick="";
 irc_msg.prefix.user="";
 irc_msg.prefix.host="";
 irc_msg.cmd.command="";
 irc_msg.cmd.num_reply=0;
 }

 boolean irc_scan(String irc_str){
 String msg=irc_str;
 String tmp="";
 char c=0;
 int  i=0;
 int  n=0;
 int  pcnt=0;
 int  ncnt=0;
 int  t;
 int len=msg.length();

 zeromemory();
 if(irc_trail(msg.charAt(0))){
 for(i=1;i<len;i++){
 c=msg.charAt(i);
 if(!irc_number(c) && !irc_special(c) && !irc_letter(c) &&!irc_host(c))
 break;
 tmp=tmp+c;
 }

 irc_msg.prefix.nick=tmp;
 //System.out.println("Prefix:"+tmp);
 tmp="";

 if(c=='!'){
 for(++i;i<len;i++){
 c=msg.charAt(i);
 if(!irc_user(c))break;
 tmp=tmp+c;
 }
 irc_msg.prefix.user=tmp;
 //System.out.println("User:"+tmp);
 tmp="";
 }

 if(c=='@'){
 for(++i;i<len;i++){
 c=msg.charAt(i);
 if(!irc_host(c))break;
 tmp=tmp+c;
 }
 irc_msg.prefix.host=tmp;
 //System.out.println("Host:"+irc_msg.prefix.host);
 tmp="";
 }

 while(irc_space(msg.charAt(i)))i++;
 }

 tmp="";
 for(;i<len;i++){
 c=msg.charAt(i);
 if(!irc_letter(c) && !irc_number(c))
 break;
 if(irc_number(c))n=1;
 tmp=tmp+c;
 ncnt++;
 }

 if(n==1 && ncnt==3)//the numeric reply of server is only 3 digits long
 irc_msg.cmd.num_reply=Integer.parseInt(tmp);
 else
 irc_msg.cmd.command=tmp;
 //System.out.println("Command:"+irc_msg.cmd.command);
 if(irc_space(c) && i<len)c=msg.charAt(++i);
 tmp="";

 for(;i<len;i++,pcnt++){
 c=msg.charAt(i);
 /*Trailing parameters can contain spaces..so break if it is a
 * ':' character and continue to the next segment for handling : characters
 * to eat all spaces in a single string variable
 */
 if(irc_eol(c) || irc_trail(c))break;
 t=i;
 while(i<len && !irc_space(msg.charAt(i))) i++;
 if(i>=len)break;

 irc_msg.params[pcnt]=msg.substring(t,i);
 }

 if(irc_trail(c)){
 for(i++;i<len;i++){
 c=msg.charAt(i);
 if(irc_eol(c))break;
 tmp=tmp+c;
 }
 irc_msg.params[pcnt++]=tmp;
 }

 irc_msg.param_cnt=pcnt;
 //for(i=0;i<pcnt;i++)
 //System.out.println("params["+i+"]:"+irc_msg.params[i]);
 return true;
 }
}

//Report Bugs at this thread.