]> git.scottworley.com Git - voter/blame_incremental - src/main.rs
Add license, README, and Changelog
[voter] / src / main.rs
... / ...
CommitLineData
1// voter: A simple CGI vote recorder, approval-voting-style
2//
3// This program is free software: you can redistribute it and/or modify it
4// under the terms of the GNU Affero General Public License as published
5// by the Free Software Foundation, version 3.
6
7use rand::prelude::*;
8use std::collections::{HashMap, HashSet};
9use std::io::prelude::*;
10use std::path::{Path, PathBuf};
11
12const DATA_PATH: &str = "/var/lib/voter";
13const COOKIE_NAME: &[u8] = b"__Secure-id";
14const COOKIE_LENGTH: usize = 12;
15
16fn validate_path(path: &str) -> Result<PathBuf, cgi::Response> {
17 let invalid_path = || cgi::text_response(404, "Invalid path");
18 if path == "/" {
19 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.)"));
20 }
21 if path.contains("..") || !path.starts_with("/") {
22 return Err(invalid_path());
23 }
24 let dir = Path::new(&format!("{DATA_PATH}{path}")).to_path_buf();
25 if !dir
26 .canonicalize()
27 .map_err(|_| invalid_path())?
28 .starts_with(DATA_PATH)
29 {
30 return Err(invalid_path());
31 }
32 if !dir.is_dir() {
33 return Err(invalid_path());
34 }
35 Ok(dir)
36}
37
38fn get_voter(request: &cgi::Request) -> Result<&[u8], cgi::Response> {
39 // Expect exactly one cookie, exactly as we generate it.
40 let cookie = request
41 .headers()
42 .get(cgi::http::header::COOKIE)
43 .map(|c| c.as_bytes())
44 .and_then(|c| c.strip_prefix(COOKIE_NAME))
45 .and_then(|c| c.strip_prefix(b"="))
46 .ok_or_else(|| cgi::text_response(400, "Invalid cookie"))?;
47 if cookie.len() != COOKIE_LENGTH || cookie.contains(&b' ') || cookie.contains(&b';') {
48 Err(cgi::text_response(400, "Invalid cookie"))
49 } else {
50 Ok(cookie)
51 }
52}
53
54fn tally_votes(dir: PathBuf) -> std::io::Result<HashMap<String, HashSet<String>>> {
55 let mut tally: HashMap<String, HashSet<String>> = HashMap::new();
56 if let Ok(vfile) = std::fs::File::open(dir.join("votes")) {
57 for liner in std::io::BufReader::new(vfile).lines() {
58 let line = liner?;
59 if let Some((voter, datum)) = line.split_once(' ') {
60 if voter.len() == COOKIE_LENGTH {
61 if let Some((vote, candidate)) = datum.split_once(' ') {
62 if vote == "0" {
63 if let Some(entry) = tally.get_mut(candidate) {
64 entry.remove(voter);
65 }
66 } else if vote == "1" {
67 tally
68 .entry(candidate.to_owned())
69 .or_default()
70 .insert(voter.to_owned());
71 }
72 }
73 }
74 }
75 }
76 }
77 Ok(tally)
78}
79
80fn make_random_id() -> [u8; COOKIE_LENGTH] {
81 let mut id = [0; COOKIE_LENGTH];
82 for i in 0..COOKIE_LENGTH {
83 while !(b'A'..=b'Z').contains(&id[i])
84 && !(b'a'..=b'z').contains(&id[i])
85 && !(b'0'..=b'9').contains(&id[i])
86 {
87 id[i] = random()
88 }
89 }
90 id
91}
92
93fn set_cookie(mut response: cgi::Response, path: &str) -> Result<cgi::Response, cgi::Response> {
94 response.headers_mut().append(
95 cgi::http::header::SET_COOKIE,
96 cgi::http::header::HeaderValue::from_bytes(
97 &[
98 COOKIE_NAME,
99 b"=",
100 &make_random_id(),
101 b"; Secure; HttpOnly; SameSite=Strict; Max-Age=30000000; Path=",
102 path.as_bytes(),
103 ]
104 .concat(),
105 )
106 .map_err(|_| cgi::text_response(503, "Couldn't make cookie"))?,
107 );
108 Ok(response)
109}
110
111const HTML_HEADER: &str = "<!DOCTYPE html>
112<html>
113 <head>
114 <meta charset=\"utf-8\">
115 <title>Vote!</title>
116 <style>
117 th { font-size: 70%; text-align: left }
118 input { transform: scale(1.5) }
119 div { animation: 2s infinite linear spin }
120 @keyframes spin {
121 from { transform:rotate(0) }
122 to { transform:rotate(1turn) }
123 }
124 </style>
125 <script>
126 window.onload = function() {
127 for (cb of document.getElementsByTagName('input')) {
128 cb.addEventListener('click', (function(cb) {
129 return function() {
130 cb.style.display = 'none'
131 const spin = document.createElement('div')
132 spin.appendChild(document.createTextNode('⏳'))
133 cb.parentElement.insertBefore(spin, cb)
134
135 const req = new XMLHttpRequest()
136 req.addEventListener('load', function(e) {
137 cb.parentElement.removeChild(cb.previousElementSibling)
138 if (req.status == 200) {
139 cb.style.display = ''
140 const delta = cb.checked ? 1 : -1
141 const count_td = cb.parentElement.previousElementSibling
142 count_td.textContent = parseInt(count_td.textContent) + delta
143 } else {
144 cb.parentElement.insertBefore(document.createTextNode('❗'), cb)
145 }
146 })
147 req.open('PUT', window.location.href)
148 req.send((cb.checked ? 1 : 0) + ' ' + cb.parentElement.nextElementSibling.innerHTML)
149 }
150 })(cb))
151 cb.disabled = false
152 }
153 }
154 function num_cmp(a, b) {
155 return parseInt(b.textContent) - parseInt(a.textContent)
156 }
157 function str_cmp(a, b) {
158 if (a.textContent < b.textContent) return -1
159 if (a.textContent > b.textContent) return 1
160 return 0
161 }
162 function checked_cmp(a, b) {
163 vs = [a, b].map(x => {
164 const v = x.children[0].checked + 0
165 return isNaN(v) ? -1 : v
166 })
167 return vs[1] - vs[0]
168 }
169 function sort_table(col, cmp) {
170 const rows = Array.from(document.getElementsByTagName('tr'))
171 rows.shift()
172 rows.sort((a, b) => cmp(a.children[col], b.children[col]))
173 for (row of rows) {
174 row.parentElement.appendChild(row)
175 }
176 }
177 </script>
178 </head>
179 <body>
180 <table>
181 <tr>
182 <th onclick='sort_table(0, num_cmp)'>Count</th>
183 <th onclick='sort_table(1, checked_cmp)'>Vote</th>
184 <th onclick='sort_table(2, str_cmp)'>Candidate</th>
185 </tr>";
186const HTML_FOOTER: &str = "
187 </table>
188 </body>
189</html>";
190
191fn supports(tally: &HashMap<String, HashSet<String>>, me: &str, candidate: &str) -> bool {
192 tally
193 .get(candidate)
194 .map(|supporters| supporters.contains(me))
195 .unwrap_or(false)
196}
197
198fn prompt_for_vote(dir: PathBuf, request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
199 let voter = get_voter(&request);
200 let me = if let Ok(id) = voter {
201 std::str::from_utf8(id).ok()
202 } else {
203 None
204 };
205 let tally =
206 tally_votes(dir.clone()).map_err(|_| cgi::text_response(503, "Couldn't tally votes"))?;
207 let cfile = std::fs::File::open(dir.join("candidates"))
208 .map_err(|_| cgi::text_response(503, "No candidates"))?;
209 let mut response = cgi::html_response(
210 200,
211 std::iter::once(Ok(HTML_HEADER.to_owned()))
212 .chain(std::io::BufReader::new(cfile).lines().map(|rc| {
213 rc.map(|c| {
214 let count = tally
215 .get(&c)
216 .map(|supporters| supporters.len())
217 .unwrap_or(0);
218 let checked = if me.map(|me| supports(&tally, me, &c)).unwrap_or(false) {
219 "checked"
220 } else {
221 ""
222 };
223 format!(
224 "<tr>
225 <td>{count}</td>
226 <td><input type=\"checkbox\" autocomplete=\"off\" {checked} disabled></td>
227 <td>{c}</td>
228 </tr>"
229 )
230 })
231 }))
232 .chain(std::iter::once(Ok(HTML_FOOTER.to_owned())))
233 .collect::<std::io::Result<String>>()
234 .map_err(|_| cgi::text_response(503, "Missing candidates"))?,
235 );
236 if voter.is_err() {
237 response = set_cookie(response, request.uri().path())?
238 }
239 Ok(response)
240}
241
242fn write_vote(dir: PathBuf, voter: &[u8], vote: &[u8]) -> std::io::Result<()> {
243 let datum = [voter, b" ", vote, b"\n"].concat();
244 let vpath = dir.join("votes");
245 let vfile = std::fs::File::options()
246 .append(true)
247 .create(true)
248 .open(vpath)?;
249 let mut vlock = fd_lock::RwLock::new(vfile);
250 vlock.write()?.write(&datum)?;
251 Ok(())
252}
253
254fn record_vote(dir: PathBuf, request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
255 let body = request.body();
256 // Valid votes look like "0 foo" or "1 bar"
257 if body.len() < 3
258 || (body[0] != b'0' && body[0] != b'1')
259 || body[1] != b' '
260 || body.contains(&b'\n')
261 {
262 return Err(cgi::text_response(415, "Invalid vote"));
263 }
264 write_vote(dir, &get_voter(&request)?, body)
265 .map_err(|_| cgi::text_response(503, "Couldn't record vote"))?;
266 Ok(cgi::text_response(200, "Vote recorded"))
267}
268
269fn strip_body(mut response: cgi::Response) -> cgi::Response {
270 response.body_mut().clear();
271 response
272}
273
274fn respond(request: cgi::Request) -> Result<cgi::Response, cgi::Response> {
275 let dir = validate_path(request.uri().path())?;
276 match request.method() {
277 &cgi::http::Method::HEAD => prompt_for_vote(dir, request).map(strip_body),
278 &cgi::http::Method::GET => prompt_for_vote(dir, request),
279 &cgi::http::Method::PUT => record_vote(dir, request),
280 _ => Err(cgi::text_response(405, "Huh?")),
281 }
282}
283
284fn respond_or_report_error(request: cgi::Request) -> cgi::Response {
285 match respond(request) {
286 Ok(result) => result,
287 Err(error) => error,
288 }
289}
290
291cgi::cgi_main! { respond_or_report_error }