Description
This is a medium difficulty project. This will serve as the foundation for the upcoming programming projects. A working client code is given to you in Client.py; this is the same client as project 0. Your job, like project 0, is to write the corresponding server code. The goal of the server is to reply to any client with the IP address of any domain name sent to it.
The server is not allowed to use gethostbyname or any similar function designed to do DNS. Instead, the server must send a UDP message to the Google DNS server at 8.8.8.8 and ask it for the IP address. This means the server will need two sockets, one server socket to talk to the client and one client socket to talk to the Google DNS server. You must construct this DNS message according to your knowledge of the protocol and the provided resources. Lastly, it should then close gracefully when the client is done sending domain names. Sample output and input files have also been provided. Note that due to certain aspects of the way DNS works, your output may not exactly match the sample; you can check if it worked by typing the IP address into your browser and making sure you get the right webpage.
If the DNS server at 8.8.8.8 sends many answers, send all of them back to the client separated by a ‘,’ character in the order that they were sent to you. If the answer is not an A record, you may simply return the string ‘OTHER’ once per a non-A answer instead of an ip address.
Here is a diagram of the header from the RFC (if these diagrams confuse you read the routly blog post from the resources).
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| ID |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
|QR| Opcode |AA|TC|RD|RA| Z | RCODE |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| QDCOUNT |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| ANCOUNT |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| NSCOUNT |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| ARCOUNT |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
and the question looks like:
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| |
/ QNAME /
/ /
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| QTYPE |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| QCLASS |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
and the answer:
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| |
/ /
/ NAME /
| |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| TYPE |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| CLASS |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| TTL |
| |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
| RDLENGTH |
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–|
/ RDATA /
/ /
+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+
See the resources for more information.
Any code that is copied from anywhere without citation INCLUDING POSTED RESOURCES or fellow classmates will be considered a violation of the academic integrity policy and dealt with appropriately. To clarify, you may use code from the posted resources, but you must cite the resource you used.
How we will test your programs
——————————
As part of your submission, you will turn in one program:Server.py and one README file (more on this below). We will be running the two programs on the ilab machines with python 3.6 . Please indicate which one you used in the README.
Please do not assume that all programs will run on the same machine or that all
connections are made to the local host. We reserve the right to test your
programs with local and remote socket connections, for example with Client.py,
And Server.py each running on a different machine. You are welcome to
simplify the initial development and debugging of your project, and get off the
ground by running all programs on one machine first. However, you must
eventually ensure that the programs can work across multiple machines.
The programs must work with the following command lines:
python Server.py PORT
python Client.py SERVERADDRESS PORT
An example of this would be:
python Server.py 5444
python Client.py vi.cs.rutgers.edu 5444
By default the client reads from a file called source_strings.txt and writes to a file called results.txt
README file
———–
In addition to your programs, you must also submit a README file with clearly
delineated sections for the following.
0. Please write down the full names and netids of both your team members.
1. Are there known issues or functions that aren’t working currently in your
attached code? If so, explain. (note that you will get half credit for any reasonably sized bug that is fully explained in the readme)
3. What problems did you face developing code for this project? Around how long did you spend on this project (This helps me decide what I need to explain more clearly for the next projects)
Submission
———-
Turn in your project on Sakai assignments. Only one team member needs to
submit. Please DO NOT ZIP your files you must submit Server.py and README
