Merge branch 'rust'

1 files changed, 72 insertions, 0 deletions

diff --git a/src/telnet.rs b/src/telnet.rs
new file mode 100644
index 0000000..c18fe53
--- /dev/null
+++ b/src/telnet.rs
@@ -0,0 +1,72 @@
+use std::io::{ErrorKind, Read, Result, Write};
+use std::net::TcpStream;
+use std::thread;
+use std::time::Duration;
+
+use crate::renderer::Renderer;
+use crate::screen::Screen;
+
+/// Parses a 16bit buffer by parsing both u8
+fn parse_16bit_buffer(buffer: &[u8]) -> u16 {
+    let high = buffer.first().unwrap_or(&0);
+    let low = buffer.get(1).unwrap_or(&0);
+    (u16::from(*high) << 8) | u16::from(*low)
+}
+
+// Telnet protocol constants
+const NAWS_REQUEST: &[u8] = &[0xFF, 0xFD, 0x1F]; // IAC DO NAWS
+const NAWS_RESPONSE_PREFIX: &[u8] = &[0xFF, 0xFB, 0x1F, 0xFF, 0xFA, 0x1F]; // IAC WILL NAWS IAC SB NAWS
+const ESCAPE_SEQUENCE: &[u8] = &[0xFF, 0xF4, 0xFF, 0xFD, 0x06]; // IAC IP IAC DO TIMING_MARK
+
+/// Selects a random screen and renderer, waits for the NAWS handshake, and
+/// starts the animation.
+pub fn handle_client(mut stream: TcpStream, frequency: u64, modulation: u8) -> Result<()> {
+    let mut buffer = [0; 1024];
+
+    let screen = Screen::random();
+    let renderer = Renderer::random();
+
+    let mut width: Option<u16> = None;
+    let mut height: Option<u16> = None;
+    let mut current_modulation: u8 = 0;
+
+    // Send NAWS request to get terminal size
+    stream.write_all(NAWS_REQUEST)?;
+    stream.flush()?;
+
+    loop {
+        stream.set_read_timeout(Some(Duration::from_millis(10)))?;
+        match stream.read(&mut buffer) {
+            Ok(0) => break, // Disconnect
+            Ok(n) => {
+                if n >= 10 && buffer[0..6] == *NAWS_RESPONSE_PREFIX {
+                    width = Some(parse_16bit_buffer(&buffer[6..8]));
+                    height = Some(parse_16bit_buffer(&buffer[8..10]));
+
+                    // Clear screen once we have dimensions
+                    stream.write_all(b"\x1B[2J")?; // Clear screen
+                    stream.flush()?;
+                }
+
+                // Check for telnet escape sequence (Ctrl+C)
+                if n >= 5 && buffer[0..5] == *ESCAPE_SEQUENCE {
+                    break;
+                }
+            }
+            Err(ref e) if e.kind() == ErrorKind::WouldBlock => {}
+            Err(_) => break,
+        }
+
+        if let (Some(w), Some(h)) = (width, height) {
+            let payload = screen.render(current_modulation, w, h, &renderer);
+            let message = format!("\x1B[1;1H{payload}"); // Reset cursor + payload
+            stream.write_all(message.as_bytes())?;
+            stream.flush()?;
+
+            current_modulation = current_modulation.wrapping_add(modulation);
+        }
+
+        thread::sleep(Duration::from_millis(frequency));
+    }
+    Ok(())
+}