Bug has developed

Applications Programming
1

Guys there is another bug that has developed.........now messaged above 6 bytes are trimmed and echoed back to client.After the first message the echo is not regular.I have put a loop in both client and server to check for closing.Moreover for connection close i also need to put another clause that if there is a connection break in either server or client the connection should be closed from other side.Below are the server and clinet side codes after connection

Server

 while(j!=0)
    {
      memset(buffer,0,1024);/*clear buffer*/
      n = read(newsockfd,buffer,1024);/*read from client*/
      if (n < 0) perror("\n ERROR reading from socket \n");/*check for errors*/
      len=strlen(buffer);
      for(i=0;i<=len;i++)
	{
	  //strcpy(buf1,&buffer);
	  //strcat(buf1,&buffer[i+1]);
	  k= strcmp("/",&buffer);
	
	  if(k==0)
	    break;
	  break;
	}
	      for(p=i;p<=len;p++)
		{
		  j= strcmp("q",&buffer[p]);
		
	      if(j==0)
		{
		  close(newsockfd);
		  close(sockfd);
		  exit(0);
		  
		}
		}
	
	      puts(buffer);/*print message by client*/
	      write(newsockfd,"\n Client wrote",14);/*write to client*/
	      n=write(newsockfd,buffer,sizeof(buffer));/*write to client*/
	      if(n<0)perror("Write Failed");
	
      
    }

Client Side

	while(k!=0)
	  {
	    memset(&buf, 0, sizeof(buf));
    printf("\n Enter Message for Server");
    gets(buf);
    rc = write(s, buf,sizeof(buf)); 
     if(rc<0)
      {
	perror("write failed");
      }
    /* now that we are connected, start writing to the socket */	
    /* till write() returns 0, meaning the server closed	*/
    /* the connection.				*/
    len=strlen(buf);
    for(i=0;i<=len;i++)
      {
	//strcpy(b1,&buf);
	//strcat(b1,&buf[i+1]);
	       
	l= strcmp("/",&buf);
      
	if(l==0)
	  break;
	break;
      }
	    for(p=i;p<=len;p++)
	      {
	    k=  strcmp("q",&buf[p]);
	    if(k==0)
	      {
		close(s);
		exit (0);
	      }
	      }

	    read(s,buf1,14);
	    read(s,buf2,1024);
	    puts(buf1);/*print messages from server*/
	    puts(buf2);/*print messages from server*/
    
    
	  }
      }
2 
if(k==0)
break;
break;

What is that supposed to achieve?

I suggest you don't use C++ style comments in C code. It's a bad habit for portable code.

3

arjunjag, be aware of the rules. No homework questions. You are getting the whole college project done by the members of the forum.

4

Very first request please use CODE tags

n = read(newsockfd,buffer,1024);/*read from client*/
if (n < 0) perror("\n ERROR reading from socket \n");/*check for errors*/

Why do you continue here even after an error ? ( after perror )
Do you want to continue even when n == 0

if(k==0)
break;
break;

Does that mean to break irrespective of the value of ' k '. Then why is that part of the code ? Anything specific here ?

if(j==0)
{
close(newsockfd);
close(sockfd);
exit(0);
}

Parent not waiting for the child to complete

write(newsockfd,"\n Client wrote",14);/*write to client*/

Flusing before writing and not after that.

n=write(newsockfd,buffer,sizeof(buffer));/*write to client*/
if(n<0)perror("Write Failed");
}

The same pattern where it continues processing even after write call returns a negative value

gets(buf);

This function would not check any buffer overrun.

try to use fgets.

:slight_smile: