Contents

RdtProtocol.java

• Abstract class that simulates a reliable data transfer protocol.
• Encapsulates a TcpPacket object in the data field of a UDP datagram.
• Capable of handling buffer overflow attacks.
• Drops out-of-order datagrams.
• Uses TCP/IP/UDP checksum to check for packet corruption.
• Simulates GBN Protocol for packet loss.
• Calculates packet Round-Trip-Times.
• Has debugging functionality.
• Logs in-order, non-corrupt received packets.

RdtReceiver.java

• Simulates a reliable receiver.
• Contains threads for sending and receiving datagrams simultaneously.

RdtSender.java

• Simulates a reliable sender.
• Contains threads for sending and receiving datagrams simultaneously.

TcpPacket.java

• An abstraction of a TCP packet.
• Contains methods for calculating TCP/IP/UDP 16-bit one's complement checksum, encoding and decoding a byte array to and from a TcpPacket object.

Timer.java

• An abstraction of a timer.
• Runs concurrent to Sender and Receiver as a separate thread.
• At any given time, timer is active for only one sent but not yet acknowledged datagram.
• Contains methods to calculate the sample, estimated, and deviation from estimate Round-Trip-Times.

Segment.java:

• An abstraction of a TCP segment containing data.
• Contains fields to track various segment properties (sent, ACKed, etc.)

Makefile

• make compiles the .java source files using the javac compiler.
• make clean will clean all auxiliary .class files.

Usage

    make
    java RdtReceiver <filename> <log_filename> <sender_IP> <sender_port>
                     <listening_port> 
                      optional: <debug>
    java RdtSender   <filename> <log_filename> <receiver_IP> <receiver_port>
                     <listening_port> <window_size>
                      optional: <debug>

• sender_port and receiver_port must be larger than well-known ports.
• window_size size must be under 32768.
• log_filename can optionally be set to stdout.

Example

make
java RdtReceiver recv.jpg stdout localhost 10988 10989 debug
java RdtSender send.jpg sendLog.txt localhost 10989 10988 32767 debug