Project 5-Implementing UDP on top of IPv4

CS380 — Project 5
(60 points)
Description
In this project, you’ll be implementing UDP on top of IPv4. To do this, you will create IPv4 packets as in
project 3, then create UDP packets as the data for the IPv4 packets. These will then be transmitted to the
server. The server will first check the IPv4 headers to ensure the IPv4 packet is constructed correctly, then
check the IPv4 data to get the UDP packet and check the header and data.
Your IPv4 headers will have the same restrictions as project 3 except the protocol should be set for UDP
instead of TCP. Keep in mind that the UDP checksum is calculated using the same method but different
input. It includes the UDP header, data, and a “pseudoheader” that includes part of the IPv4 header.
Our programs will perform the following procedure:
(1) First, we’ll do a “handshaking” step where you send a single IPv4 packet (no UDP here) with 4 bytes
of data hard-coded to 0xDEADBEEF. Then, my server will respond first with the response code for that
packet (4 bytes, see below table) then with 2 bytes of raw data (not an IP packet, so you don’t need to be
able to parse incoming IP packets) which you should treat as an unsigned 16-bit integer corresponding
to a port number.
Note that if your response code here doesn’t come back with 0xCAFEBABE don’t expect the next two
bytes to be sent.
(2) You will then send UDP packets (inside of IPv4 packets) with the destination port header field assigned
to the number you received in the previous step. You should send packets as follows: send 12 total
packets with data size starting at 2 bytes and doubling each time. The UDP source port can be set to
anything you like but the data must be randomized1
.
(3) After sending each UDP packet, wait for the server response which will contain exactly 4 bytes hardcoded to 0xCAFEBABE if your packet was constructed correctly. Print out the server response and
the elapsed time in milliseconds since you sent the packet (an estimate for the RTT) for each packet
transmitted. After sending all 12 packets print the mean RTT for all 12 packets.
Here’s a list of potential response codes:
Code Reason
0xCAFEBABE Everything looks fine
0xBAADF00D Problem with IPv4 portion of packet (see project 3 to fix!)
0xCAFED00D Incorrect destination port in UDP packet
0xDEADC0DE Invalid UDP checksum
0xBBADBEEF Incorrect UDP data length
The host to connect to is codebank.xyz and the port is 38005.
1You can use Java’s java.util.Random class and the nextBytes(byte[] b) method.
1
Sample Output
You must indicate the handshake response, identify each UDP packet, indicate the UDP packet responses,
list the RTT for each packet, and show the final average RTT.
This is an example of how your output might look:
$ java UdpClient
Handshake response: 0xCAFEBABE
Port number received: 50058
Sending packet with 2 bytes of data
Response: 0xCAFEBABE
RTT: 51ms
Sending packet with 4 bytes of data
Response: 0xCAFEBABE
RTT: 43ms
Sending packet with 8 bytes of data
Response: 0xCAFEBABE
RTT: 50ms
Sending packet with 16 bytes of data
Response: 0xCAFEBABE
RTT: 41ms
Sending packet with 32 bytes of data
Response: 0xCAFEBABE
RTT: 41ms
Sending packet with 64 bytes of data
Response: 0xCAFEBABE
RTT: 40ms
Sending packet with 128 bytes of data
Response: 0xCAFEBABE
RTT: 41ms
Sending packet with 256 bytes of data
Response: 0xCAFEBABE
RTT: 51ms
Sending packet with 512 bytes of data
Response: 0xCAFEBABE
RTT: 41ms
Sending packet with 1024 bytes of data
Response: 0xCAFEBABE
RTT: 46ms
Sending packet with 2048 bytes of data
2
Response: 0xCAFEBABE
RTT: 44ms
Sending packet with 4096 bytes of data
Response: 0xCAFEBABE
RTT: 47ms
Average RTT: 44.67ms