Base64_Encoding_System

Base64 encoding communication protocol implementation using TCP sockets.

In this assignment, I have implemented two CPP programs, namely server and client to communicate with each other based on TCP sockets. The aim is to implement simple Base64 encoding communication protocol.

Initially, server will be waiting for a TCP connection from the client. Then, client will connect to the server using server’s TCP port already known to the client. After successful connection, the client accepts the text input from the user and encodes the input using Base64 encoding system. Once encoded message is computed the client sends the Message (Type 1 message) to the server via TCP port. After receiving the Message, server should print the received and original message by decoding the received message, and sends an ACK (Type 2 message) to the client. The client and server should remain in a loop to communicate any number of messages. Once the client wants to close the communication, it should send a Message (Type 3 Message) to the server and the TCP connection on both the server and client should be closed gracefully by releasing the socket resource.

The messages used to communicate contain the following fields:

Message_ Type | Message

1. Message_type : integer.
2. Message : Character [MSG_LEN], where MSG_LEN is an integer constant.
3. < Message> content of the message in Type 3 message can be anything.

Here the server implemented is a "Concurrent Server", i.e., a server that accepts connections from multiple clients and serves all of them concurrently.

Inputs

IP Address and Port number are inputed from the command line.

Client: <executable code><Server IP Address><Server Port number>

Server: <executable code><Server Port number>

To Compile

Client: g++ -o client Client.cpp

Server: g++ -o server Server.cpp

To Run

Server: server portno

Client: client hostname portno

Base64 Encoding System Description

Base64 encoding is used for sending a binary message over the internet. In this scheme, groups of 24bit are broken into four 6 bit groups and each group is encoded with an ASCII character. For binary values 0 to 25 ASCII character ‘A’ to ‘Z’ are used followed by lower case letters and the digits for binary values 26 to 51 & 52 to 61 respectively. Character ‘+’ and ‘/’ are used for binary value 62 & 63 respectively. In case the last group contains only 8 & 16 bits, then “==” & “=” sequence are appended to the end.