(feat): rename example-usage to just example

(feat): add the example's web-client dist folder to a gitignore
(fix): format issues
(fix): a lot of duplicate code

example/server/src/tls.rs

@@ -0,0 +1,70 @@
+use std::fs;
+use std::path::Path;
+
+use base64::Engine;
+
+pub fn load_or_generate_tls(
+    cert_path: &str,
+    key_path: &str,
+) -> Result<(Vec<u8>, Vec<u8>), Box<dyn std::error::Error>> {
+    if let (Ok(c), Ok(k)) = (fs::read(cert_path), fs::read(key_path)) {
+        println!("Using existing TLS cert from {cert_path}");
+        return Ok((c, k));
+    }
+
+    println!("Generating self-signed TLS certificate ...");
+    if let Some(parent) = Path::new(cert_path).parent() {
+        fs::create_dir_all(parent)?;
+    }
+    if let Some(parent) = Path::new(key_path).parent() {
+        fs::create_dir_all(parent)?;
+    }
+    let key_pair = rcgen::KeyPair::generate()?;
+    let params = rcgen::CertificateParams::new(vec!["localhost".into(), "127.0.0.1".into()])?;
+    let cert = params.self_signed(&key_pair)?;
+
+    let cert_str = cert.pem();
+    let key_str = key_pair.serialize_pem();
+
+    fs::write(cert_path, cert_str.as_bytes())?;
+    fs::write(key_path, key_str.as_bytes())?;
+    println!("Wrote {cert_path} and {key_path}");
+
+    Ok((cert_str.into_bytes(), key_str.into_bytes()))
+}
+
+pub fn certificate_sha256_hex(cert: &[u8]) -> Result<String, Box<dyn std::error::Error>> {
+    let der = if cert.starts_with(b"-----BEGIN CERTIFICATE-----") {
+        let pem = std::str::from_utf8(cert)?;
+        let base64 = pem
+            .lines()
+            .filter(|line| !line.starts_with("-----"))
+            .collect::<String>();
+        base64::engine::general_purpose::STANDARD.decode(base64)?
+    } else {
+        cert.to_vec()
+    };
+
+    Ok(hex::encode(mtp::crypto::sha256(&der)))
+}
+
+pub fn export_webtransport_cert_hash(hash: &str) -> Result<(), Box<dyn std::error::Error>> {
+    let public_dir = if Path::new("web-client").exists() {
+        Path::new("web-client/public")
+    } else {
+        Path::new("example/web-client/public")
+    };
+    fs::create_dir_all(public_dir)?;
+    fs::write(public_dir.join("mtp_dev_cert_hash.txt"), hash)?;
+
+    let dev_cert_dir = if Path::new("dev-cert").exists() {
+        Path::new("dev-cert")
+    } else {
+        Path::new("example/dev-cert")
+    };
+    if dev_cert_dir.exists() {
+        fs::write(dev_cert_dir.join("sha256.txt"), hash)?;
+    }
+
+    Ok(())
+}