From 03bbbbddc4400a6aae18da4ca0b3f39fd057cabc Mon Sep 17 00:00:00 2001
From: Daniel Bulant <danbulant@gmail.com>
Date: Sun, 28 May 2023 11:19:12 +0200
Subject: [PATCH] Initial commit

---
 .gitignore  |  1 +
 Cargo.toml  | 13 +++++++++++
 src/main.rs | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Cargo.toml
 create mode 100644 src/main.rs

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.toml b/Cargo.toml
new file mode 100644
index 0000000..3140bd5
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "tcp-spawner"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+tokio = { version = "1", features = ["full"] }
+tokio-stream = "0.1"
+os_pipe = "1.1.4"
+tokio-util = { version = "0.7.8", features = ["compat"] }
+futures-util = { version = "0.3.28", features = ["io"] }
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..3924aa0
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,62 @@
+use std::env::args;
+use std::net::TcpListener;
+use tokio::process::Command;
+use tokio::io;
+use futures_util::io::AllowStdIo;
+
+
+fn build_command_from_args(args: &[String]) -> Command {
+    let mut command = Command::new(args.get(0).unwrap());
+
+    command.stdout(std::process::Stdio::piped());
+    command.stderr(std::process::Stdio::piped());
+
+    for arg in args.iter().skip(1) {
+        command.arg(arg);
+    }
+
+    command
+}
+
+#[tokio::main]
+/// This is a simple TCP server that will spawn a process for each connection
+/// and pipe the connection to the process stdin and stdout.
+/// The first argument is the port to listen on.
+/// The second argument (and later arguments) is the command to run.
+async fn main() -> io::Result<()> {
+    let args = args().collect::<Vec<String>>();
+    let listener = TcpListener::bind(args.get(1).unwrap())?;
+    let listener = tokio::net::TcpListener::from_std(listener)?;
+
+    loop {
+        let (mut stream, _) = listener.accept().await.unwrap();
+        let mut command = build_command_from_args(args.get(2..).unwrap());
+
+        println!("Got connection from {:?}", stream.peer_addr());
+
+        tokio::spawn(async move {
+            let (mut stream_reader, mut stream_writer) = stream.split();
+
+            let (child_reader, child_writer) = os_pipe::pipe().unwrap();
+            let writer_clone = child_writer.try_clone().unwrap();
+            command.stdout(child_writer);
+            command.stderr(writer_clone);
+
+            let child_reader = AllowStdIo::new(child_reader);
+            let mut child_reader = tokio_util::compat::FuturesAsyncReadCompatExt::compat(child_reader);
+
+            let mut child = command.spawn().unwrap();
+
+            let mut stdin = child.stdin.take().unwrap();
+
+            let copy_stdin = io::copy(&mut stream_reader, &mut stdin);
+            let copy_output = io::copy(&mut child_reader, &mut stream_writer);
+
+            drop(command);
+
+            tokio::try_join!(copy_stdin, copy_output).unwrap();
+
+            child.wait().await.unwrap();
+        });
+    }
+}