Sockets: running actors get TCP, UDP, and DNS through wasi:sockets; candidates get no network

cli/tests/actors/toolbox/src/main.rs

@@ -16,6 +16,15 @@ fn reply(out: &mut impl Write, message: &Value, body: Value) {
     );
 }
 
+/// Connect to `address`, send one line, and return the line that comes back.
+fn tcp_line(address: &str, line: &str) -> io::Result<String> {
+    let mut stream = std::net::TcpStream::connect(address)?;
+    writeln!(stream, "{line}")?;
+    let mut answer = String::new();
+    io::BufReader::new(stream).read_line(&mut answer)?;
+    Ok(answer.trim_end().to_string())
+}
+
 fn io_error(error: io::Error) -> Value {
     json!({"type": "error", "error": error.to_string()})
 }
@@ -131,6 +140,10 @@ fn main() {
                 json!({"type": "armed"})
             }
             Some("ignore-stdin") => json!({"type": "ignoring"}),
+            Some("tcp") => match tcp_line(body["address"].as_str().unwrap_or_default(), text) {
+                Ok(line) => json!({"type": "tcp", "line": line}),
+                Err(error) => io_error(error),
+            },
             Some("read") => match std::fs::read_to_string(&path) {
                 Ok(text) => json!({"type": "content", "text": text}),
                 Err(error) => io_error(error),