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|
pub mod argparse;
use std::collections::HashMap;
use std::io::{self, prelude::*};
use std::net::{IpAddr, TcpListener, TcpStream};
use std::process::ExitCode;
use std::sync::{
Arc,
atomic::{AtomicBool, Ordering},
};
use std::thread::sleep;
use std::time::Duration;
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
enum Flag {
Help,
Version,
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
enum Param {
Port,
Address,
Timeout,
MaxConnections,
}
fn print_version() {
println!(
"{} v. {}",
env!("CARGO_PKG_NAME"),
env!("CARGO_PKG_VERSION")
);
}
fn print_doc() {
print_version();
println!("{}", include_str!("../README.txt"));
}
#[derive(Debug)]
struct ConnectionSettings {
timeout: u32,
buffer: [u8; 1024],
}
const SLEEP_MS_PER_ROUND: u32 = 50;
impl ConnectionSettings {
/// handle this connection as much as possible *without blocking*
#[must_use]
fn handle_connection(&mut self, addr: IpAddr, conn: &mut Connection) -> bool {
let buffer = &mut self.buffer;
conn.age_ms += SLEEP_MS_PER_ROUND;
if conn.age_ms > self.timeout * 1000 {
return false;
}
if conn.state < 4 {
let n = match conn.stream.read(buffer) {
Ok(n) => n,
Err(e) if e.kind() == io::ErrorKind::WouldBlock => 0,
Err(e) => {
eprintln!("WARNING: error reading from connection: {e}");
return false;
}
};
for &c in &buffer[..n] {
if c != b'\r' && c != b'\n' {
continue;
}
let expected = if conn.state % 2 == 0 { b'\r' } else { b'\n' };
if c == expected {
conn.state += 1;
if conn.state == 4 {
break;
}
}
}
}
if conn.state == 4 {
// 90B is more than long enough for our response
write!(
&mut buffer[..90],
"HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n{addr}\n\0"
)
.expect("?? writing address to buffer failed??");
let length = buffer[..90]
.iter()
.position(|&c| c == 0)
.expect("?? no null byte even though we just wrote one??");
match conn
.stream
.write(&buffer[usize::from(conn.written)..length])
{
Ok(n) => {
conn.written += n as u8;
if conn.written >= length as u8 {
// hooray! done sending response
return false;
}
}
Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
// keep connection around
}
Err(e) => {
eprintln!("WARNING: error writing to connection: {e}");
return false;
}
}
}
true
}
}
#[derive(Debug)]
struct Connection {
stream: TcpStream,
/// rough time connection has been around in milliseconds
age_ms: u32,
/// number of characters out of \r\n\r\n (end of HTTP headers) that we have
state: u8,
/// number of characters of address which have been written
written: u8,
}
fn try_main() -> Result<(), Box<dyn std::error::Error>> {
let args = argparse::parse_args(
&HashMap::from_iter([("--help", Flag::Help), ("--version", Flag::Version)]),
&HashMap::from([
("--port", Param::Port),
("--address", Param::Address),
("--timeout", Param::Timeout),
("--max-connections", Param::MaxConnections),
]),
)?;
if args.is_set(Flag::Help) {
print_doc();
return Ok(());
}
if args.is_set(Flag::Version) {
print_version();
return Ok(());
}
let addr = args.get(Param::Address).unwrap_or("0.0.0.0");
let port = args.get(Param::Port).unwrap_or("80");
let port = port
.parse::<u16>()
.map_err(|_| format!("Invalid port: {port}"))?;
let timeout = args.get(Param::Timeout).unwrap_or("15");
let timeout = timeout
.parse::<u32>()
.map_err(|_| format!("Invalid timeout: {timeout}"))?;
let max_connections = args.get(Param::MaxConnections).unwrap_or("32");
let max_connections = max_connections
.parse::<u32>()
.map_err(|_| format!("Invalid max connections: {max_connections}"))?;
let listener = TcpListener::bind((addr, port))
.map_err(|e| format!("Couldn't bind on {addr}:{port}: {e}"))?;
let interrupted = Arc::new(AtomicBool::new(false));
let handler_interrupted = interrupted.clone();
if let Err(e) = ctrlc::set_handler(move || {
handler_interrupted.store(true, Ordering::Relaxed);
}) {
eprintln!("Warning: Couldn't set SIGINT/TERM handler: {e}");
}
listener
.set_nonblocking(true)
.map_err(|e| format!("Couldn't set socket to non-blocking: {e}"))?;
let was_interrupted = || interrupted.load(Ordering::Relaxed);
let mut connections: HashMap<IpAddr, Connection> = HashMap::new();
let mut settings = ConnectionSettings {
timeout,
buffer: [0; 1024],
};
'outer: while !was_interrupted() {
sleep(Duration::from_millis(SLEEP_MS_PER_ROUND.into())); // don't busy loop
while (connections.len() as u32) < max_connections {
match listener.accept() {
Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
if was_interrupted() {
break 'outer;
}
break;
}
Err(e) => eprintln!("Warning: accept() failed: {e}"),
Ok((stream, source_addr)) => {
if let Err(e) = stream.set_nonblocking(true) {
eprintln!(
"WARNING: dropping connection because set_nonblocking failed: {e}"
);
continue;
}
// if there was another connection from this address, it gets
// unceremoniously dropped. too bad.
connections.insert(
source_addr.ip(),
Connection {
stream,
age_ms: 0,
written: 0,
state: Default::default(),
},
);
}
}
}
connections.retain(|addr, conn| settings.handle_connection(*addr, conn));
}
Ok(())
}
fn main() -> ExitCode {
if let Err(e) = try_main() {
eprintln!("Error: {e}");
return ExitCode::FAILURE;
}
ExitCode::SUCCESS
}
|
