Add the inferproxy byte forwarder with its two limits

Implemented-By: Laguna S 2.1 (OpenCode)

crates/inferproxy/src/main.rs

@@ -1,4 +1,68 @@
+use std::env;
+use std::fs;
+use std::os::unix::fs::PermissionsExt;
+use std::path::PathBuf;
+use std::process;
+
+use inferproxy::{Limits, serve};
+
 fn main() {
-    eprintln!("inferproxy: not implemented until M2");
-    std::process::exit(2);
+    let args: Vec<String> = env::args().collect();
+    let mut listen: Option<String> = None;
+    let mut upstream: Option<String> = None;
+    let mut i = 1;
+    while i < args.len() {
+        match args[i].as_str() {
+            "--listen" => {
+                i += 1;
+                listen = args.get(i).cloned();
+            }
+            "--upstream" => {
+                i += 1;
+                upstream = args.get(i).cloned();
+            }
+            _ => usage(),
+        }
+        i += 1;
+    }
+    let listen = match listen {
+        Some(p) => p,
+        None => usage(),
+    };
+    let upstream = match upstream {
+        Some(p) => p,
+        None => usage(),
+    };
+
+    let path: PathBuf = listen.into();
+    match fs::remove_file(&path) {
+        Ok(()) => {}
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
+        Err(e) => {
+            eprintln!("inferproxy: cannot remove stale socket: {e}");
+            process::exit(1);
+        }
+    }
+    let listener = match std::os::unix::net::UnixListener::bind(&path) {
+        Ok(l) => l,
+        Err(e) => {
+            eprintln!("inferproxy: bind failed: {e}");
+            process::exit(1);
+        }
+    };
+    let perms = fs::Permissions::from_mode(0o600);
+    if let Err(e) = fs::set_permissions(&path, perms) {
+        eprintln!("inferproxy: chmod failed: {e}");
+        process::exit(1);
+    }
+    eprintln!("inferproxy: {} -> {}", path.display(), upstream);
+    if let Err(e) = serve(listener, upstream, Limits::default()) {
+        eprintln!("inferproxy: {e}");
+        process::exit(1);
+    }
+}
+
+fn usage() -> ! {
+    eprintln!("usage: inferproxy --listen <socket path> --upstream <host:port>");
+    process::exit(2);
 }