STUN Client and Server

Session Traversal Utilities for NAT (STUN) is a protocol to discover a client's public ip address and determine any restrictions in the client's router/firewall that would prevent a direct peer connection. This implementation only focuses on the Binding Request and Binding Response portion.

This STUN server receives Binding Request messages, validates them, and replies with a Binding Response message. This STUN client sends Binding Request messages and cosumes/decodes a Binding Response from the server.

This is primarily a teaching tool for Rust systems programming (UDP, header encoding/decoding, ...etc.) in the WebRTC domain.

Benchmarks

To run the Criterion benchmarks:

cargo bench

Output

send and receive binding request and response
                        time:   [180.04 ns 180.14 ns 180.22 ns]
                        change: [-0.0304% +0.1749% +0.4260%] (p = 0.15 > 0.05)
                        No change in performance detected.
Found 9 outliers among 100 measurements (9.00%)
  5 (5.00%) low severe
  4 (4.00%) low mild

To view the HTML reports, navigate to target/criterion/send-and-receive-binding-request-and-response/report/index.html.

Examples

Configuration

Copy the .env.example file to .env

cp .env.example .env

Now update the values in .env as needed.

Running the Server

Running the server will listen for incoming UDP packets and accept Binding Request messages:

RUST_LOG=info cargo run --example server

Output

INFO  server > Started stun server on 0.0.0.0:8082

Running the Client

Running the client will instantly send a Binding Request message (UDP packet):

RUST_LOG=info cargo run --example client

Output

INFO  client > Started stun client on 0.0.0.0:8081, connected to a stun server on 0.0.0.0:8082
INFO  client > sending binding request to the server: Message { class: Request, method: Binding, transaction_id: TransactionId([216, 15, 139, 140, 54, 166, 55, 187, 63, 53, 116, 133]), attributes: [] }

Running the Client and Server Examples

To run the client and server at the same time time, where a binding request is sent and a binding response is received:

RUST_LOG=info cargo run --example client_server

Output

INFO  client_server::server > Started stun server on 0.0.0.0:8082
INFO  client_server::client > Started stun client on 0.0.0.0:8081, connected to a stun server on 0.0.0.0:8082
INFO  client_server::client > sending binding request to the server: Message { class: Request, method: Binding, transaction_id: TransactionId([208, 75, 17, 165, 14, 198, 154, 57, 125, 86, 149, 161]), attributes: [] }
INFO  client_server::server > received 20 bytes from 127.0.0.1:8081: Message { class: Request, method: Binding, transaction_id: TransactionId([208, 75, 17, 165, 14, 198, 154, 57, 125, 86, 149, 161]), attributes: [] }
INFO  client_server::server > sending message to client: Message { class: SuccessResponse, method: Binding, transaction_id: TransactionId([185, 55, 136, 17, 149, 163, 157, 110, 142, 158, 190, 150]), attributes: [XorMappedAddress(Address { address: [127, 0, 0, 1], port: 8081, ip_kind: IPv4 })] }
INFO  client_server::client > received 20 bytes from 127.0.0.1:8082: Message { class: SuccessResponse, method: Binding, transaction_id: TransactionId([185, 55, 136, 17, 149, 163, 157, 110, 142, 158, 190, 150]), attributes: [] }