Implement the initial handshake

src/handshake.rs

@@ -0,0 +1,23 @@
+pub const CONFIG_END: &str = "config|ready";
+pub const CONFIG_TAG: &str = "config|";
+
+pub fn read_config() {
+	let mut buffer = String::new();
+	let stdin = std::io::stdin();
+	loop {
+		buffer.clear();
+		stdin.read_line(&mut buffer).unwrap();
+		let entry = buffer.trim_end();
+		if entry == CONFIG_END {
+			return;
+		}
+		if !entry.starts_with(CONFIG_TAG) {
+			eprintln!("invalid config line: {entry}");
+		}
+	}
+}
+
+pub fn register_filter() {
+	println!("register|filter|smtp-in|data-line");
+	println!("register|ready");
+}

src/main.rs

@@ -1,3 +1,6 @@
+mod handshake;
+
 fn main() {
-    println!("Hello, world!");
+	handshake::read_config();
+	handshake::register_filter();
 }