Select based TCP messaging server

This repository contains code for basic concurrent TCP messaging server which reads client request using select system call and iterates over them rather than creating a child process for every client.

Compiling

• Type following command to generate executable server

   $ make

Running

• To run server type

   $ ./server <port>

  port is the port number on which TCP messaging server will listen requests. Default port is 6500.

• Telnet could be used as client application. To run client through telnet type following command

   $ telnet localhost <port>

  port is the port number on which TCP messaging server is running.

• To add a client to a particular group type the following message in telnet

   GROUP$<ID>

  here ID is the group number to which client should be added.Value of ID could be from 0 to MAX_GROUPS defined in header.
  For e.g. typing

   GROUP$2

  will add the client to group number 2.

• To send the message to all the clients in a group type following message in telnet

   GROUPMSG$<ID>$<MSG>

  here ID is the group number to which message should be sent and MSG is message to be sent.
  For e.g. typing

   GROUPMSG$2$AASD

  will send AASD to all the clients present in group 2.

• To send the message to all the clients connected irrespective of group type the message directly in telnet.
  For e.g. typing

   asad

  will send asad to all the clients connected.

Basic Explanation

• Client connects to server. Server adds client's file descriptor into an array.
• Clients send messages to server to which server responds by selecting file descriptors iteratively through select system all.
• If client requests to be added in a group add client's file descriptor into a 2D array of groupinfo having row as group number and column having client's file descriptors.
• If message is to be sent to all the clients in a group iterate through that group's row in groupinfo array and send message to all the clients.
• If message is to be sent to all the clients iterate through file descriptor array and send message to all the clients.

TODOS

• Add command to remove client from group.