git.scottworley.com Git - voter/blob - src/main.rs

   1 use std::io::prelude::*;
   2 use std::path::{Path, PathBuf};
   3
   4 const DATA_PATH: &str = "/var/lib/voter";
   5 const COOKIE_NAME: &[u8] = b"__Secure-id";
   6 const COOKIE_LENGTH: usize = 32;
   7
   8 fn validate_path(path: &str) -> Result<PathBuf, cgi::Response> {
   9     let invalid_path = || cgi::text_response(404, "Invalid path");
  10     if path == "/" {
  11         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.)"));
  12     }
  13     if path.contains("..") || !path.starts_with("/") {
  14         return Err(invalid_path());
  15     }
  16     let dir = Path::new(&format!("{DATA_PATH}{path}")).to_path_buf();
  17     if !dir
  18         .canonicalize()
  19         .map_err(|_| invalid_path())?
  20         .starts_with(DATA_PATH)
  21     {
  22         return Err(invalid_path());
  23     }
  24     if !dir.is_dir() {
  25         return Err(invalid_path());
  26     }
  27     Ok(dir)
  28 }
  29
  30 fn get_voter(request: &cgi::Request) -> Result<&[u8], cgi::Response> {
  31     // Expect exactly one cookie, exactly as we generate it.
  32     let cookie = request
  33         .headers()
  34         .get(cgi::http::header::COOKIE)
  35         .map(|c| c.as_bytes())
  36         .and_then(|c| c.strip_prefix(COOKIE_NAME))
  37         .and_then(|c| c.strip_prefix(b"="))
  38         .ok_or_else(|| cgi::text_response(400, "Invalid cookie"))?;
  39     if cookie.len() != COOKIE_LENGTH || cookie.contains(&b' ') || cookie.contains(&b';') {
  40         Err(cgi::text_response(400, "Invalid cookie"))
  41     } else {
  42         Ok(cookie)
  43     }
  44 }
  45
  46 fn prompt_for_vote(dir: PathBuf, request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
  47     Err(cgi::text_response(503, "Not Implemented"))
  48 }
  49
  50 fn write_vote(dir: PathBuf, voter: &[u8], vote: &[u8]) -> std::io::Result<()> {
  51     let datum = [voter, b" ", vote, b"\n"].concat();
  52     let vpath = dir.join("votes");
  53     let vfile = std::fs::File::options()
  54         .append(true)
  55         .create(true)
  56         .open(vpath)?;
  57     let mut vlock = fd_lock::RwLock::new(vfile);
  58     vlock.write()?.write(&datum)?;
  59     Ok(())
  60 }
  61
  62 fn record_vote(dir: PathBuf, request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
  63     let body = request.body();
  64     // Valid votes look like "0 foo" or "1 bar"
  65     if body.len() < 3
  66         || (body[0] != b'0' && body[0] != b'1')
  67         || body[1] != b' '
  68         || body.contains(&b'\n')
  69     {
  70         return Err(cgi::text_response(415, "Invalid vote"));
  71     }
  72     write_vote(dir, &get_voter(&request)?, body)
  73         .map_err(|_| cgi::text_response(503, "Couldn't record vote"))?;
  74     Ok(cgi::text_response(200, "Vote recorded"))
  75 }
  76
  77 fn strip_body(mut response: cgi::Response) -> cgi::Response {
  78     response.body_mut().clear();
  79     response
  80 }
  81
  82 fn respond(request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
  83     let dir = validate_path(request.uri().path())?;
  84     match request.method() {
  85         &cgi::http::Method::HEAD => prompt_for_vote(dir, request).map(strip_body),
  86         &cgi::http::Method::GET => prompt_for_vote(dir, request),
  87         &cgi::http::Method::PUT => record_vote(dir, request),
  88         _ => Err(cgi::text_response(405, "Huh?")),
  89     }
  90 }
  91
  92 fn respond_or_report_error(request: cgi::Request) -> cgi::Response {
  93     match respond(request) {
  94         Ok(result) => result,
  95         Err(error) => error,
  96     }
  97 }
  98
  99 cgi::cgi_main! { respond_or_report_error }