+const DATA_PATH: &str = "/var/lib/voter";
+const COOKIE_NAME: &[u8] = b"__Secure-id";
+const COOKIE_LENGTH: usize = 12;
+
+fn validate_path(path: &str) -> Result<PathBuf, cgi::Response> {
+ let invalid_path = || cgi::text_response(404, "Invalid path");
+ if path == "/" {
+ return Err(cgi::text_response(404, "(This is the voting place. You should have been given a more specific URL for the specific thing you've been invited to vote on.)"));
+ }
+ if path.contains("..") || !path.starts_with("/") {
+ return Err(invalid_path());
+ }
+ let dir = Path::new(&format!("{DATA_PATH}{path}")).to_path_buf();
+ if !dir
+ .canonicalize()
+ .map_err(|_| invalid_path())?
+ .starts_with(DATA_PATH)
+ {
+ return Err(invalid_path());
+ }
+ if !dir.is_dir() {
+ return Err(invalid_path());
+ }
+ Ok(dir)
+}
+
+fn get_voter(request: &cgi::Request) -> Result<&[u8], cgi::Response> {
+ // Expect exactly one cookie, exactly as we generate it.
+ let cookie = request
+ .headers()
+ .get(cgi::http::header::COOKIE)
+ .map(|c| c.as_bytes())
+ .and_then(|c| c.strip_prefix(COOKIE_NAME))
+ .and_then(|c| c.strip_prefix(b"="))
+ .ok_or_else(|| cgi::text_response(400, "Invalid cookie"))?;
+ if cookie.len() != COOKIE_LENGTH || cookie.contains(&b' ') || cookie.contains(&b';') {
+ Err(cgi::text_response(400, "Invalid cookie"))
+ } else {
+ Ok(cookie)
+ }
+}
+
+fn make_random_id() -> [u8; COOKIE_LENGTH] {
+ let mut id = [0; COOKIE_LENGTH];
+ for i in 0..COOKIE_LENGTH {
+ while !(b'A'..=b'Z').contains(&id[i])
+ && !(b'a'..=b'z').contains(&id[i])
+ && !(b'0'..=b'9').contains(&id[i])
+ {
+ id[i] = random()
+ }
+ }
+ id
+}
+
+fn set_cookie(mut response: cgi::Response, path: &str) -> Result<cgi::Response, cgi::Response> {
+ response.headers_mut().append(
+ cgi::http::header::SET_COOKIE,
+ cgi::http::header::HeaderValue::from_bytes(
+ &[
+ COOKIE_NAME,
+ b"=",
+ &make_random_id(),
+ b"; Secure HttpOnly SameSite=Strict Max-Age=30000000 Path=",
+ path.as_bytes(),
+ ]
+ .concat(),
+ )
+ .map_err(|_| cgi::text_response(503, "Couldn't make cookie"))?,
+ );
+ Ok(response)
+}
+
+const HTML_HEADER: &str = "<!DOCTYPE html>
+<html>
+ <head>
+ <meta charset=\"utf-8\">
+ <title>Vote!</title>
+ <style>
+ input { transform: scale(1.5) }
+ div { animation: 2s infinite linear spin }
+ @keyframes spin {
+ from { transform:rotate(0) }
+ to { transform:rotate(1turn) }
+ }
+ </style>
+ <script>
+ window.onload = function() {
+ for (cb of document.getElementsByTagName('input')) {
+ cb.addEventListener('click', (function(cb) {
+ return function() {
+ cb.style.display = 'none'
+ const spin = document.createElement('div')
+ spin.appendChild(document.createTextNode('⏳'))
+ cb.parentElement.insertBefore(spin, cb)
+ }
+ })(cb))
+ cb.disabled = false
+ }
+ }
+ </script>
+ </head>
+ <body>
+ <table>";
+const HTML_FOOTER: &str = "
+ </table>
+ </body>
+</html>";
+
+fn prompt_for_vote(dir: PathBuf, request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
+ let voter = get_voter(&request);
+ let cfile = std::fs::File::open(dir.join("candidates"))
+ .map_err(|_| cgi::text_response(503, "No candidates"))?;
+ let mut response = cgi::html_response(
+ 200,
+ std::iter::once(Ok(HTML_HEADER.to_owned()))
+ .chain(std::io::BufReader::new(cfile).lines().map(|rc| {
+ rc.map(|c| {
+ format!("<tr><td><input type=\"checkbox\" disabled></td><td>{c}</td></tr>")
+ })
+ }))
+ .chain(std::iter::once(Ok(HTML_FOOTER.to_owned())))
+ .collect::<std::io::Result<String>>()
+ .map_err(|_| cgi::text_response(503, "Missing candidates"))?,
+ );
+ if voter.is_err() {
+ response = set_cookie(response, request.uri().path())?
+ }
+ Ok(response)
+}
+
+fn write_vote(dir: PathBuf, voter: &[u8], vote: &[u8]) -> std::io::Result<()> {
+ let datum = [voter, b" ", vote, b"\n"].concat();
+ let vpath = dir.join("votes");
+ let vfile = std::fs::File::options()
+ .append(true)
+ .create(true)
+ .open(vpath)?;
+ let mut vlock = fd_lock::RwLock::new(vfile);
+ vlock.write()?.write(&datum)?;
+ Ok(())
+}
+
+fn record_vote(dir: PathBuf, request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
+ let body = request.body();
+ // Valid votes look like "0 foo" or "1 bar"
+ if body.len() < 3
+ || (body[0] != b'0' && body[0] != b'1')
+ || body[1] != b' '
+ || body.contains(&b'\n')
+ {
+ return Err(cgi::text_response(415, "Invalid vote"));
+ }
+ write_vote(dir, &get_voter(&request)?, body)
+ .map_err(|_| cgi::text_response(503, "Couldn't record vote"))?;
+ Ok(cgi::text_response(200, "Vote recorded"))
+}
+
+fn strip_body(mut response: cgi::Response) -> cgi::Response {
+ response.body_mut().clear();
+ response
+}
+
+fn respond(request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
+ let dir = validate_path(request.uri().path())?;
+ match request.method() {
+ &cgi::http::Method::HEAD => prompt_for_vote(dir, request).map(strip_body),
+ &cgi::http::Method::GET => prompt_for_vote(dir, request),
+ &cgi::http::Method::PUT => record_vote(dir, request),
+ _ => Err(cgi::text_response(405, "Huh?")),
+ }
+}
+
+fn respond_or_report_error(request: cgi::Request) -> cgi::Response {
+ match respond(request) {
+ Ok(result) => result,
+ Err(error) => error,
+ }
projects / voter / blobdiff