| 1 | //! A small HTTP/1.1 server: one request per connection, bodies by Content-Length. |
| 2 | //! |
| 3 | //! grove sits behind Caddy, which handles TLS, HTTP/2 and keep-alive towards clients; this |
| 4 | //! side only has to be correct and bounded. |
| 5 | |
| 6 | use std::io::{self, BufRead, BufReader, Read, Write}; |
| 7 | use std::net::{TcpListener, TcpStream}; |
| 8 | use std::sync::atomic::{AtomicUsize, Ordering}; |
| 9 | use std::sync::Arc; |
| 10 | use std::time::Duration; |
| 11 | |
| 12 | const MAX_HEAD: usize = 64 << 10; |
| 13 | pub const MAX_BODY: usize = 512 << 20; |
| 14 | const MAX_CONNECTIONS: usize = 128; |
| 15 | |
| 16 | pub struct Request { |
| 17 | pub method: String, |
| 18 | pub path: String, |
| 19 | pub query: String, |
| 20 | pub headers: Vec<(String, String)>, |
| 21 | pub body: Vec<u8>, |
| 22 | } |
| 23 | |
| 24 | impl Request { |
| 25 | pub fn header(&self, name: &str) -> Option<&str> { |
| 26 | self.headers.iter().find(|(k, _)| k.eq_ignore_ascii_case(name)).map(|(_, v)| v.as_str()) |
| 27 | } |
| 28 | } |
| 29 | |
| 30 | pub struct Response { |
| 31 | pub status: u16, |
| 32 | pub content_type: String, |
| 33 | pub headers: Vec<(&'static str, String)>, |
| 34 | pub body: Vec<u8>, |
| 35 | } |
| 36 | |
| 37 | impl Response { |
| 38 | pub fn json(status: u16, v: &crate::json::Value) -> Response { |
| 39 | Response::with(status, "application/json", v.encode().into_bytes()) |
| 40 | } |
| 41 | pub fn bytes(body: Vec<u8>) -> Response { |
| 42 | Response::with(200, "application/octet-stream", body) |
| 43 | } |
| 44 | pub fn with(status: u16, content_type: &str, body: Vec<u8>) -> Response { |
| 45 | Response { status, content_type: content_type.to_string(), headers: Vec::new(), body } |
| 46 | } |
| 47 | pub fn html(status: u16, page: String) -> Response { |
| 48 | Response::with(status, "text/html; charset=utf-8", page.into_bytes()) |
| 49 | } |
| 50 | pub fn header(mut self, name: &'static str, value: impl Into<String>) -> Response { |
| 51 | self.headers.push((name, value.into())); |
| 52 | self |
| 53 | } |
| 54 | pub fn error(status: u16, msg: &str) -> Response { |
| 55 | Response::json(status, &crate::json::obj([("error", msg.into())])) |
| 56 | } |
| 57 | } |
| 58 | |
| 59 | fn reason(status: u16) -> &'static str { |
| 60 | match status { |
| 61 | 200 => "OK", |
| 62 | 302 => "Found", |
| 63 | 303 => "See Other", |
| 64 | 400 => "Bad Request", |
| 65 | 401 => "Unauthorized", |
| 66 | 403 => "Forbidden", |
| 67 | 404 => "Not Found", |
| 68 | 405 => "Method Not Allowed", |
| 69 | 409 => "Conflict", |
| 70 | 411 => "Length Required", |
| 71 | 413 => "Payload Too Large", |
| 72 | 500 => "Internal Server Error", |
| 73 | 503 => "Service Unavailable", |
| 74 | _ => "", |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | fn bad(msg: &str) -> io::Error { |
| 79 | io::Error::new(io::ErrorKind::InvalidData, msg.to_string()) |
| 80 | } |
| 81 | |
| 82 | /// Read one request. Errors carry the status to answer with. |
| 83 | fn read_request(stream: &TcpStream) -> Result<Request, (u16, String)> { |
| 84 | let mut reader = BufReader::new(stream); |
| 85 | let mut head = Vec::new(); |
| 86 | loop { |
| 87 | let mut line = Vec::new(); |
| 88 | let n = reader.read_until(b'\n', &mut line).map_err(|e| (400, e.to_string()))?; |
| 89 | if n == 0 { |
| 90 | return Err((400, "connection closed".into())); |
| 91 | } |
| 92 | head.extend_from_slice(&line); |
| 93 | if head.len() > MAX_HEAD { |
| 94 | return Err((413, "headers too large".into())); |
| 95 | } |
| 96 | if line == b"\r\n" || line == b"\n" { |
| 97 | break; |
| 98 | } |
| 99 | } |
| 100 | let head = String::from_utf8(head).map_err(|_| (400, "headers aren't UTF-8".to_string()))?; |
| 101 | let mut lines = head.lines(); |
| 102 | let first = lines.next().unwrap_or(""); |
| 103 | let mut parts = first.split(' '); |
| 104 | let (method, target, version) = (parts.next().unwrap_or(""), parts.next().unwrap_or(""), parts.next().unwrap_or("")); |
| 105 | if method.is_empty() || !target.starts_with('/') || !version.starts_with("HTTP/1.") { |
| 106 | return Err((400, "bad request line".into())); |
| 107 | } |
| 108 | let mut headers = Vec::new(); |
| 109 | for line in lines { |
| 110 | if line.is_empty() { |
| 111 | break; |
| 112 | } |
| 113 | let (k, v) = line.split_once(':').ok_or((400, "bad header".to_string()))?; |
| 114 | headers.push((k.trim().to_string(), v.trim().to_string())); |
| 115 | } |
| 116 | let find = |name: &str| headers.iter().find(|(k, _)| k.eq_ignore_ascii_case(name)).map(|(_, v)| v.clone()); |
| 117 | if find("transfer-encoding").is_some() { |
| 118 | return Err((411, "send a Content-Length".into())); |
| 119 | } |
| 120 | let len = match find("content-length") { |
| 121 | Some(v) => v.parse::<usize>().map_err(|_| (400, "bad Content-Length".to_string()))?, |
| 122 | None => 0, |
| 123 | }; |
| 124 | if len > MAX_BODY { |
| 125 | return Err((413, "body too large".into())); |
| 126 | } |
| 127 | let mut body = vec![0u8; len]; |
| 128 | reader.read_exact(&mut body).map_err(|e| (400, e.to_string()))?; |
| 129 | let (path, query) = match target.split_once('?') { |
| 130 | Some((p, q)) => (p.to_string(), q.to_string()), |
| 131 | None => (target.to_string(), String::new()), |
| 132 | }; |
| 133 | Ok(Request { method: method.to_string(), path, query, headers, body }) |
| 134 | } |
| 135 | |
| 136 | fn write_response(stream: &mut TcpStream, r: &Response) -> io::Result<()> { |
| 137 | let mut head = format!("HTTP/1.1 {} {}\r\nContent-Type: {}\r\nContent-Length: {}\r\n", r.status, reason(r.status), r.content_type, r.body.len()); |
| 138 | for (k, v) in &r.headers { |
| 139 | // Header values come from the server itself, but never let one end the head early. |
| 140 | if !v.contains(['\r', '\n']) { |
| 141 | head += &format!("{k}: {v}\r\n"); |
| 142 | } |
| 143 | } |
| 144 | head += "Connection: close\r\n\r\n"; |
| 145 | stream.write_all(head.as_bytes())?; |
| 146 | stream.write_all(&r.body)?; |
| 147 | stream.flush() |
| 148 | } |
| 149 | |
| 150 | pub type Handler = Arc<dyn Fn(Request) -> Response + Send + Sync>; |
| 151 | |
| 152 | /// Accept connections forever, each on its own thread, at most MAX_CONNECTIONS at once. |
| 153 | pub fn serve(listener: TcpListener, handler: Handler) -> io::Result<()> { |
| 154 | let active = Arc::new(AtomicUsize::new(0)); |
| 155 | for stream in listener.incoming() { |
| 156 | let mut stream = match stream { |
| 157 | Ok(s) => s, |
| 158 | Err(_) => continue, |
| 159 | }; |
| 160 | if active.load(Ordering::SeqCst) >= MAX_CONNECTIONS { |
| 161 | let _ = write_response(&mut stream, &Response::error(503, "busy")); |
| 162 | continue; |
| 163 | } |
| 164 | active.fetch_add(1, Ordering::SeqCst); |
| 165 | let (handler, active) = (handler.clone(), active.clone()); |
| 166 | std::thread::spawn(move || { |
| 167 | let _ = stream.set_read_timeout(Some(Duration::from_secs(60))); |
| 168 | let _ = stream.set_write_timeout(Some(Duration::from_secs(60))); |
| 169 | let response = match read_request(&stream) { |
| 170 | // A bug in one request must not take the server down: answer 500 and carry on. |
| 171 | Ok(req) => std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| handler(req))) |
| 172 | .unwrap_or_else(|_| Response::error(500, "internal error")), |
| 173 | Err((status, msg)) => Response::error(status, &msg), |
| 174 | }; |
| 175 | let _ = write_response(&mut stream, &response); |
| 176 | active.fetch_sub(1, Ordering::SeqCst); |
| 177 | }); |
| 178 | } |
| 179 | Err(bad("listener closed")) |
| 180 | } |