15-441/15-641 Project 1: Mixnet

Project 1 for the 15-441/641 (Networking and the Internet) course at CMU. Note: This is a course project, so DO NOT push your solution to a public fork of this repo.

Requirements

This project is designed to run on Linux. It has been tested on Ubuntu 20.04.2+, but you may get away with using other distributions.

Building

You need cmake to build the project. On Ubuntu, you can install this with:

sudo apt install build-essential cmake

To build the project, in the root directory, run:

mkdir build
cd build
cmake ..
make

From now on you can always build the project by going to the build directory and running make.

Running

Mixnet is test-driven. You can find some examples of these tests under the testing directory. For instance, cp1/testcase_line_easy.cpp demonstrates how to create a line topology with two nodes, 'subscribe' to packet data from both of them, and send a FLOOD packet from one to the other.

You can run mixnet in two modes: autotester mode, which we will be using to grade your implementation, and manual mode, which you can use to debug your implementation on either a single machine (using one process per mixnet node) or a cluster of machines. You will also use the manual mode to perform experiments on AWS (please see the handout for details).

To run in autotester mode, cd into the build directory and run:

./bin/cp1/testcase_line_easy -a # '-a' toggles the autotester

At the end, it should produce output indicating whether your implementation passed or failed that particular test-case.

You can also run the same test in 'manual' mode. For the testcase_line_easy example, you will need three terminal windows open: one for each of the two mixnet nodes, and one for the 'orchestrator', which bootstraps the topology, sets up connections, coordinates actions, etc. In general, you will need (n + 1) terminals, where n is the number of mixnet nodes in the test topology. First, start the orchestrator:

./bin/cp1/testcase_line_easy # Note that '-a' is missing

You should see output that looks like this: [Orchestrator] Started listening on port 9107. Note the port (it's always 9107) the orchestrator is running on. Next, type the following command in each of the other two terminals:

./bin/node 127.0.0.1 9107

The format is as follows: ./node {server_ip} {server_port} (also see ./bin/node -h). The {server_ip} argument corresponds to the public IPv4 address of the machine on which the orchestrator is running; since we are running everything locally, we can simply use the machine's loopback address (127.0.0.1). Please refer to the other test-cases, as well as the test API in framework/orchestrator.h for more examples and detailed usage.

The entry-point to your code is the run_node() function in mixnet/node.c. For details, please refer to the handout. Good luck!