commit cf43bfebfbc61cbb1f1f6ba88ae4ea15c57436d9
Author: TudbuT <tudbut@tudbut.de>
Date:   Sat Aug 13 01:13:57 2022 +0200

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..aa1331f
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "qft"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..641a8b1
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "qft"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..d0d344d
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,307 @@
+use std::{
+    fs::File,
+    io::{Error, Read, Write},
+    net::*,
+    time::Duration,
+};
+
+trait Ordinal {
+    fn ordinal(&self) -> isize;
+}
+
+enum SafeReadWritePacket {
+    WRITE,
+    ACK,
+    END,
+}
+
+impl Ordinal for SafeReadWritePacket {
+    fn ordinal(&self) -> isize {
+        match self {
+            SafeReadWritePacket::WRITE => 0,
+            SafeReadWritePacket::ACK => 1,
+            SafeReadWritePacket::END => 2,
+        }
+    }
+}
+
+struct SafeReadWrite {
+    socket: UdpSocket,
+    packet_count_out: u8,
+    packet_count_in: u8,
+}
+
+impl SafeReadWrite {
+    pub fn new(socket: UdpSocket) -> SafeReadWrite {
+        SafeReadWrite {
+            socket,
+            packet_count_in: 0,
+            packet_count_out: 0,
+        }
+    }
+
+    pub fn write_safe(&mut self, buf: &[u8]) -> Result<(), Error> {
+        if buf.len() > 0xfffd {
+            panic!(
+                "too large data packet sent over SafeReadWrite ({} > 0xfffd)",
+                buf.len()
+            );
+        }
+
+        let id = self.packet_count_out;
+        self.packet_count_out += 1;
+
+        let mut buf = Vec::from(buf);
+        buf.insert(0, SafeReadWritePacket::WRITE.ordinal() as u8);
+        buf.insert(0, id);
+        let buf = buf.as_slice();
+
+        self.socket
+            .set_read_timeout(Some(Duration::from_secs(1)))
+            .expect("cannot set_read_timeout");
+
+        let mut resend = true;
+        while resend {
+            match self.socket.send(buf) {
+                Ok(x) => {
+                    if x != buf.len() {
+                        panic!("bad buf length")
+                    }
+                }
+                Err(x) => return Err(x),
+            }
+            let mut buf = [0, 0];
+            match self.socket.recv(&mut buf).ok() {
+                Some(x) => {
+                    if x == 0 {
+                        continue;
+                    }
+                    if buf[1] == SafeReadWritePacket::ACK.ordinal() as u8 && buf[0] == id {
+                        resend = false;
+                    }
+                }
+                None => {}
+            }
+        }
+        return Ok(());
+    }
+
+    pub fn read_safe(&mut self, buf: &[u8]) -> Result<(Vec<u8>, usize), Error> {
+        if buf.len() > 0xfffd {
+            panic!(
+                "attempted to receive too large data packet with SafeReadWrite ({} > 0xfffd)",
+                buf.len()
+            );
+        }
+
+        let mut mbuf = Vec::from(buf);
+        mbuf.insert(0, 0);
+        mbuf.insert(0, 0);
+        let buf: &mut [u8] = mbuf.as_mut();
+
+        let mut r = (vec![], 0);
+
+        let mut try_again = true;
+        while try_again {
+            match self.socket.recv(buf) {
+                Ok(x) => {
+                    if x == 0 {
+                        continue;
+                    }
+                    if buf[0] <= self.packet_count_in {
+                        self.socket
+                            .send(&[buf[0], SafeReadWritePacket::ACK.ordinal() as u8])
+                            .expect("send error");
+                    }
+                    if buf[0] == self.packet_count_in {
+                        try_again = false;
+                        self.packet_count_in += 1;
+                        r.1 = x - 2;
+                    }
+                    if buf[0] > self.packet_count_in {
+                        panic!("illegal packet id {} > {}", buf[0], self.packet_count_in);
+                    }
+                    if buf[1] == SafeReadWritePacket::END.ordinal() as u8 {
+                        return Ok((vec![], 0));
+                    }
+                }
+                Err(x) => return Err(x),
+            }
+        }
+        mbuf.remove(0);
+        mbuf.remove(0);
+        r.0 = mbuf;
+        return Ok(r);
+    }
+
+    pub fn end(mut self) -> UdpSocket {
+        let id = self.packet_count_out;
+        self.packet_count_out += 1;
+
+        let mut buf = vec![];
+        buf.insert(0, SafeReadWritePacket::END.ordinal() as u8);
+        buf.insert(0, id);
+        let buf = buf.as_slice();
+
+        self.socket
+            .set_read_timeout(Some(Duration::from_secs(1)))
+            .expect("cannot set_read_timeout");
+
+        let mut resend = true;
+        while resend {
+            match self.socket.send(buf) {
+                Ok(x) => {
+                    if x != buf.len() {
+                        panic!("internet down")
+                    }
+                }
+                Err(_) => return self.socket,
+            }
+            let mut buf = [0, 0];
+            match self.socket.recv(&mut buf).ok() {
+                Some(x) => {
+                    if x == 0 {
+                        continue;
+                    }
+                    if buf[1] == SafeReadWritePacket::ACK.ordinal() as u8 && buf[0] == id {
+                        resend = false;
+                    }
+                }
+                None => {}
+            }
+        }
+
+        self.socket
+    }
+
+    pub fn get_socket(&self) -> &UdpSocket {
+        &self.socket
+    }
+
+    pub fn get_mut_socket(&mut self) -> &mut UdpSocket {
+        &mut self.socket
+    }
+}
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() <= 1 {
+        print_args(&args);
+    }
+    match args
+        .get(1)
+        .expect("no args supplied, check if the first arg is truly the program name")
+        .as_str()
+    {
+        "helper" => helper(&args),
+        "sender" => sender(&args),
+        "receiver" => receiver(&args),
+        _ => print_args(&args),
+    }
+}
+
+fn helper(args: &Vec<String>) {
+    let bind_addr = (
+        "127.0.0.1",
+        u16::from_str_radix(args[2].as_str(), 10).expect("invalid port: must be integer"),
+    );
+    let listener = UdpSocket::bind(&bind_addr).expect("unable to create socket");
+    let mut buf = [0 as u8];
+    loop {
+        let (_, addr) = listener.recv_from(&mut buf).expect("read error");
+        // we got a connection
+        if listener.send_to(&addr.port().to_be_bytes(), addr).is_ok() {
+            // success!
+            println!("Helped {}! :D", addr);
+        }
+    }
+}
+
+fn sender(args: &Vec<String>) {
+    let mut bind_addr = ("127.0.0.1", 0);
+    {
+        let holepunch = UdpSocket::bind(&bind_addr).expect("unable to create socket");
+        let mut buf = [0 as u8; 2];
+        holepunch
+            .connect(args.get(2).unwrap_or_else(|| {
+                print_args(args);
+                panic!("unreachable")
+            }))
+            .expect("unable to connect to helper");
+        holepunch.send(&[0]).expect("unable to talk to helper");
+        holepunch
+            .recv(&mut buf)
+            .expect("unable to receive from helper");
+        // buf should now contain our port.
+        bind_addr = ("127.0.0.1", u16::from_be_bytes(buf));
+        println!("Holepunch successful. Running on port {}.", bind_addr.1);
+    }
+    // we have the needed bind_addr and did the holepunch
+    {
+        let connection = UdpSocket::bind(&bind_addr).expect("unable to create send socket");
+        let mut buf = [0 as u8; 256];
+        let mut file = File::open(args.get(3).unwrap_or_else(|| {
+            print_args(args);
+            panic!("unreachable")
+        }))
+        .expect("file not readable");
+        connection
+            .connect(connection.recv_from(&mut buf).expect("connect error").1)
+            .expect("connect error");
+
+        let mut sc = SafeReadWrite::new(connection);
+        loop {
+            let read = file.read(&mut buf).expect("file read error");
+            if read == 0 {
+                println!("Transfer done. Thank you!");
+                sc.end();
+                return;
+            }
+
+            sc.write_safe(&buf[..read]).expect("send error");
+            println!("Sent {} bytes", read);
+        }
+    }
+}
+
+fn receiver(args: &Vec<String>) {
+    let connection = UdpSocket::bind(("127.0.0.1", 0)).expect("unable to create receive socket");
+    let mut buf: &[u8] = &[0 as u8; 256];
+    let mut file = File::create(args.get(3).unwrap_or_else(|| {
+        print_args(args);
+        panic!("unreachable")
+    }))
+    .expect("file not writable");
+    connection
+        .connect(args.get(2).unwrap_or_else(|| {
+            print_args(args);
+            panic!("unreachable")
+        }))
+        .expect("unable to connect");
+    connection.send(&[0]).expect("connect write error");
+
+    let mut sc = SafeReadWrite::new(connection);
+    loop {
+        let (mbuf, len) = sc.read_safe(buf).expect("read error");
+        buf = &mbuf.leak()[..len];
+        if len == 0 {
+            println!("Transfer done. Thank you!");
+            return;
+        }
+
+        file.write(buf).expect("write error");
+        println!("Received {} bytes", len);
+    }
+}
+
+fn print_args(args: &Vec<String>) {
+    let f = args.get(0).unwrap();
+    println!(
+        "No arguments. Needed: \n\
+         | {} helper <bind-port>\n\
+         | {} sender <helper-address>:<helper-port> <filename>\n\
+         | {} receiver <sender-address>:<sender-port> <filename>",
+        f, f, f
+    );
+    panic!("No arguments");
+}