Implement NAWS (negotiate about window size)

src/frame_view.rs

@@ -2,7 +2,7 @@ use std::collections::HashMap;
 
 use gc_arena::Collect;
 use wasm_bindgen::prelude::*;
-use web_sys::{Element, Node};
+use web_sys::{console, Element, Node};
 use yew::prelude::*;
 
 use crate::{
@@ -164,7 +164,15 @@ fn get_or_make_term_frame<'a>(
                             .ok()
                     })
                 })
-                .unwrap_or(())
+                .unwrap_or(());
+            let mut engine = globals_for_resize.lua_engine.borrow_mut();
+            match engine.dispatch_resize(&frame_for_resize, dims.cols(), dims.rows()) {
+                Err(e) => console::log_1(&JsValue::from_str(&format!(
+                    "Error sending resize to Lua: {}",
+                    e
+                ))),
+                Ok(()) => {}
+            }
         });
         term.onResize(&resize_closure);
 

src/lua_engine.rs

@@ -1,5 +1,6 @@
 use self::{frameroutes::*, frames::*, muds::*, storage::*};
 use anyhow::Error;
+use muds::telopt::configure_telopt_table;
 use piccolo::{
     async_callback::{AsyncSequence, Locals},
     meta_ops::{self, MetaResult},
@@ -127,6 +128,31 @@ impl LuaState {
         self.interp.execute(&self.exec)?;
         Ok(())
     }
+
+    pub(crate) fn dispatch_resize(
+        &mut self,
+        frame: &FrameId,
+        width: u16,
+        height: u16,
+    ) -> anyhow::Result<()> {
+        self.interp.try_enter(|ctx| {
+            let frames: Table = ctx.get_global("frames")?;
+            let frame_tab: Value = frames.get(ctx, frame.0 as i64)?;
+            if frame_tab.is_nil() {
+                Err(anyhow::Error::msg(
+                    "Dispatching command to frame missing in Lua frames.",
+                ))?;
+            }
+            ctx.fetch(&self.exec).restart(
+                ctx,
+                Function::Callback(send_resize_to_frame(ctx)),
+                (frame_tab, width, height),
+            );
+            Ok(())
+        })?;
+        self.interp.execute(&self.exec)?;
+        Ok(())
+    }
 }
 
 pub fn install_lua_globals(
@@ -209,6 +235,11 @@ pub fn install_lua_globals(
             ctx.set_global("commands", cmd_table);
             let info_table = Table::new(&ctx);
             ctx.set_global("info", info_table);
+
+            let telopt_table = Table::new(&ctx);
+            let _ = info_table.set(ctx, "telopts", telopt_table);
+            configure_telopt_table(ctx, &telopt_table);
+
             let muds_table = Table::new(&ctx);
             ctx.set_global("muds", muds_table);
             let frames_table = Table::new(&ctx);
@@ -284,6 +315,8 @@ pub fn install_lua_globals(
             register_class_function!(mud_class_table, mudinput_line);
             register_class_function!(mud_class_table, "closed", mudclass_closed);
             register_stateless_class_function!(mud_class_table, "new", new_mud);
+            register_class_function!(mud_class_table, "term_resized", mud_term_resized);
+            register_class_function!(mud_class_table, local_naws_enabled);
 
             macro_rules! register_class_nop {
                 ($class_table: ident, $sym: ident) => {
@@ -308,6 +341,7 @@ pub fn install_lua_globals(
             frame_class_table.set(ctx, MetaMethod::Index, frame_class_table)?;
             register_class_function!(frame_class_table, "new", new_frame);
             register_class_function!(frame_class_table, "input", frame_input);
+            register_class_function!(frame_class_table, "resize", frame_resize);
 
             let frameroute_class_table = Table::new(&ctx);
             classes_table.set(ctx, "frameroute", frameroute_class_table)?;
@@ -384,14 +418,15 @@ pub fn prep_metaop_call<'gc, const N: usize>(
     }
 }
 
-pub async fn call_checking_metatable<'gc, T: Fetchable>(
+pub async fn call_checking_metatable<'gc, T: Fetchable, FN>(
     seq: &mut AsyncSequence,
     obj: T,
-    func_name: &'static str,
+    func_name: FN,
     arguments: &[StashedValue],
 ) -> Result<(), StashedError>
 where
     for<'gcb> <T as Fetchable>::Fetched<'gcb>: IntoValue<'gcb>,
+    for<'gcb> FN: IntoValue<'gcb>,
 {
     let call = seq.try_enter(|ctx, locals, _execution, mut stack| {
         let obj = locals.fetch(&obj);
@@ -400,11 +435,7 @@ where
             ctx,
             stack,
             locals,
-            meta_ops::index(
+            meta_ops::index(ctx, obj.into_value(ctx), func_name.into_value(ctx))?,
-                ctx,
-                obj.into_value(ctx),
-                ctx.intern_static(func_name.as_bytes()).into_value(ctx),
-            )?,
         ))
     })?;
     if let Some(call) = call {

src/lua_engine/frames.rs

@@ -106,7 +106,8 @@ pub fn list_match_tab<'gc>(
         let frame = locals.stash(&ctx, intern_id(ctx, frame));
         let aliases = locals.stash(&ctx, aliases);
         async move {
-            call_checking_metatable::<StashedUserData>(&mut seq, aliases, "lua_table", &[]).await?;
+            call_checking_metatable::<StashedUserData, _>(&mut seq, aliases, "lua_table", &[])
+                .await?;
             let echo_func = seq.try_enter(|ctx, locals, _ex, mut stack| {
                 let alias_tab: Table = stack.consume(ctx)?;
                 stack.push_back(locals.fetch(&frame).into_value(ctx));
@@ -321,7 +322,7 @@ pub fn ensure_frame_instance<'gc>(ctx: Context<'gc>, frame: &FrameId) -> Callbac
             let frame_tab = locals.stash(&ctx, frame_tab);
             let frame = locals.stash(&ctx, frame);
             async move {
-                call_checking_metatable::<StashedTable>(&mut seq, frame_tab, "new", &[frame])
+                call_checking_metatable::<StashedTable, _>(&mut seq, frame_tab, "new", &[frame])
                     .await?;
                 Ok(SequenceReturn::Return)
             }
@@ -372,7 +373,8 @@ pub(super) fn send_command_to_frame<'gc>(ctx: Context<'gc>) -> Callback<'gc> {
             let frame = locals.stash(&ctx, frame);
             let line = locals.stash(&ctx, line.into_value(ctx));
             async move {
-                call_checking_metatable::<StashedTable>(&mut seq, frame, "input", &[line]).await?;
+                call_checking_metatable::<StashedTable, _>(&mut seq, frame, "input", &[line])
+                    .await?;
                 Ok(SequenceReturn::Return)
             }
         });
@@ -403,7 +405,7 @@ pub(super) fn frame_input<'gc>(ctx: Context<'gc>, _global_memo: &GlobalMemoCell)
                 let frame_tab = locals.stash(&ctx, frame_tab);
                 let frame = locals.stash(&ctx, frame);
                 async move {
-                    call_checking_metatable::<StashedUserData>(
+                    call_checking_metatable::<StashedUserData, _>(
                         &mut seq,
                         aliases.clone(),
                         "try_run_sub",
@@ -426,7 +428,7 @@ pub(super) fn frame_input<'gc>(ctx: Context<'gc>, _global_memo: &GlobalMemoCell)
                         return Ok(SequenceReturn::Return);
                     }
 
-                    call_checking_metatable::<StashedValue>(
+                    call_checking_metatable::<StashedValue, _>(
                         &mut seq,
                         linked_mud,
                         "mudinput_line",
@@ -444,6 +446,77 @@ pub(super) fn frame_input<'gc>(ctx: Context<'gc>, _global_memo: &GlobalMemoCell)
     })
 }
 
+pub(super) fn send_resize_to_frame<'gc>(ctx: Context<'gc>) -> Callback<'gc> {
+    Callback::from_fn(&ctx, move |ctx, _ex, mut stack| {
+        let (frame, width, height): (Table, u16, u16) = stack.consume(ctx)?;
+        let seq = async_sequence(&ctx, |locals, mut seq| {
+            let frame = locals.stash(&ctx, frame);
+            let width = locals.stash(&ctx, width.into_value(ctx));
+            let height = locals.stash(&ctx, height.into_value(ctx));
+            async move {
+                call_checking_metatable::<StashedTable, _>(
+                    &mut seq,
+                    frame,
+                    "resize",
+                    &[width, height],
+                )
+                .await?;
+                Ok(SequenceReturn::Return)
+            }
+        });
+        Ok(CallbackReturn::Sequence(seq))
+    })
+}
+
+pub(super) fn frame_resize<'gc>(ctx: Context<'gc>, _global_memo: &GlobalMemoCell) -> Callback<'gc> {
+    Callback::from_fn(&ctx, move |ctx, _ex, mut stack| {
+        let callback_return = {
+            let frame_tab: Table = Table::from_value(
+                ctx,
+                stack
+                    .pop_front()
+                    .ok_or_else(|| anyhow::Error::msg("classes.frame:resize missing object!"))?,
+            )?;
+            let width: Value = stack
+                .pop_front()
+                .ok_or_else(|| anyhow::Error::msg("classes.frame:resize missing width!"))?;
+            let height: Value = stack
+                .pop_front()
+                .ok_or_else(|| anyhow::Error::msg("classes.frame:resize missing height!"))?;
+            stack.consume(ctx)?;
+
+            frame_tab.set(ctx, "width", width)?;
+            frame_tab.set(ctx, "height", height)?;
+
+            let linked_mud: Value = frame_tab.get(ctx, "linked_mud")?;
+
+            if linked_mud.is_nil() {
+                return Ok(piccolo::CallbackReturn::Return);
+            }
+
+            let seq = async_sequence(&ctx, |locals, mut seq| {
+                let width = locals.stash(&ctx, width);
+                let height = locals.stash(&ctx, height);
+                let linked_mud = locals.stash(&ctx, linked_mud);
+                async move {
+                    call_checking_metatable::<StashedValue, _>(
+                        &mut seq,
+                        linked_mud,
+                        "term_resized",
+                        &[width, height],
+                    )
+                    .await?;
+
+                    Ok(SequenceReturn::Return)
+                }
+            });
+
+            Ok(piccolo::CallbackReturn::Sequence(seq))
+        };
+        callback_return
+    })
+}
+
 fn list_timers<'gc>(
     ctx: Context<'gc>,
     global_memo: &GlobalMemoCell,

src/lua_engine/muds.rs

@@ -14,14 +14,15 @@ use crate::{
     id_intern::{intern_id, unintern_id},
     logging::{start_deleting_logs, start_downloading_logs, start_listing_logs},
     match_table::{create_match_table, match_table_add, match_table_remove},
-    telnet::{parse_telnet_buf, TelnetOutput},
+    telnet::{parse_telnet_buf, TelnetOutput, IAC},
     websocket::{connect_websocket, send_message_to_mud, WebSocketId},
     FrameId, GlobalLayoutCell, GlobalMemoCell,
 };
 
 use self::telopt::{
-    handle_incoming_do, handle_incoming_dont, handle_incoming_will, handle_incoming_wont,
+    get_option_state, handle_incoming_do, handle_incoming_dont, handle_incoming_will,
-    MudWithMemo, Telopt,
+    handle_incoming_wont, send_subnegotiation_if_allowed, set_option_supported, MudWithMemo,
+    OptionState, Side, Telopt, NAWS_TELOPT,
 };
 
 use super::{call_checking_metatable, list_match_tab, try_unwrap_frame, LuaState};
@@ -87,8 +88,13 @@ pub(super) fn mudclose<'gc>(ctx: Context<'gc>, _global_memo: &GlobalMemoCell) ->
         let seq = piccolo::async_sequence(&ctx, |locals, mut seq| {
             let conntab = locals.stash(&ctx, conntab);
             async move {
-                call_checking_metatable::<StashedTable>(&mut seq, conntab.clone(), "closed", &[])
+                call_checking_metatable::<StashedTable, _>(
-                    .await?;
+                    &mut seq,
+                    conntab.clone(),
+                    "closed",
+                    &[],
+                )
+                .await?;
                 Ok(piccolo::SequenceReturn::Return)
             }
         });
@@ -169,12 +175,17 @@ pub(super) fn connect_mud<'gc>(
     let global_memo = global_memo.clone();
     Callback::from_fn(&ctx, move |ctx, _ex, mut stack| {
         let mut trusted: bool = false;
+        let mut naws: bool = true;
         let name: String = loop {
             let v: String = stack.from_front(ctx)?;
             if v == "-trust" {
                 trusted = true;
                 continue;
             }
+            if v == "-no_naws" {
+                naws = false;
+                continue;
+            }
             break v;
         };
         let name: Value<'gc> = ctx.intern(name.as_bytes()).into();
@@ -225,11 +236,16 @@ pub(super) fn connect_mud<'gc>(
                 }
             }
         }
+
+        if naws {
+            set_option_supported(ctx, &conntab, &NAWS_TELOPT, &Side::Us);
+        }
+
         // Call conntab:new...
         let seq = async_sequence(&ctx, |locals, mut seq| {
             let conntab = locals.stash(&ctx, conntab);
             async move {
-                call_checking_metatable::<StashedTable>(&mut seq, conntab, "new", &[]).await?;
+                call_checking_metatable::<StashedTable, _>(&mut seq, conntab, "new", &[]).await?;
                 Ok(SequenceReturn::Return)
             }
         });
@@ -344,7 +360,7 @@ pub(super) fn mudoutput<'gc>(ctx: Context<'gc>, _global_memo: &GlobalMemoCell) -
                             .collect();
                         async move {
                             for (func_name, params) in fns {
-                                call_checking_metatable::<StashedTable>(
+                                call_checking_metatable::<StashedTable, _>(
                                     &mut seq,
                                     conntab.clone(),
                                     func_name,
@@ -434,7 +450,7 @@ pub(super) fn mudoutput_line<'gc>(
             let triggers = locals.stash(&ctx, triggers);
             let default_frame = locals.stash(&ctx, default_frame);
             async move {
-                call_checking_metatable::<StashedUserData>(
+                call_checking_metatable::<StashedUserData, _>(
                     &mut seq,
                     triggers,
                     "try_run_sub",
@@ -442,7 +458,7 @@ pub(super) fn mudoutput_line<'gc>(
                 )
                 .await?;
                 for frameroute in frameroutes {
-                    call_checking_metatable::<StashedTable>(
+                    call_checking_metatable::<StashedTable, _>(
                         &mut seq,
                         frameroute,
                         "route",
@@ -463,6 +479,19 @@ pub(super) fn mudoutput_prompt<'gc>(
 ) -> Callback<'gc> {
     Callback::from_fn(&ctx, move |_ctx, _ex, _stack| Ok(CallbackReturn::Return))
 }
+
+fn name_telopt(ctx: Context, optno: u8) -> anyhow::Result<String> {
+    for (k, v) in ctx
+        .get_global::<Table>("info")?
+        .get::<_, Table>(ctx, "telopts")?
+    {
+        if u8::from_value(ctx, v)? == optno {
+            return Ok(String::from_value(ctx, k)?);
+        }
+    }
+    Ok(format!("{}", optno))
+}
+
 pub(super) fn mudoutput_will<'gc>(
     ctx: Context<'gc>,
     global_memo: &GlobalMemoCell,
@@ -477,8 +506,26 @@ pub(super) fn mudoutput_will<'gc>(
             memo: global_memo.clone(),
             mud: socket.clone(),
         };
-        handle_incoming_will(ctx, &mut mud_memo, &mud, &Telopt(optno));
+        if handle_incoming_will(ctx, &mut mud_memo, &mud, &Telopt(optno)) {
-        Ok(CallbackReturn::Return)
+            let seq = async_sequence(&ctx, move |locals, mut seq| {
+                let mud = locals.stash(&ctx, mud);
+                async move {
+                    let name =
+                        seq.try_enter(|ctx, _locals, _ex, _stack| Ok(name_telopt(ctx, optno)?))?;
+                    call_checking_metatable::<StashedTable, _>(
+                        &mut seq,
+                        mud,
+                        format!("remote_{}_enabled", name),
+                        &[],
+                    )
+                    .await?;
+                    Ok(SequenceReturn::Return)
+                }
+            });
+            Ok(CallbackReturn::Sequence(seq))
+        } else {
+            Ok(CallbackReturn::Return)
+        }
     })
 }
 pub(super) fn mudoutput_wont<'gc>(
@@ -510,8 +557,26 @@ pub(super) fn mudoutput_do<'gc>(ctx: Context<'gc>, global_memo: &GlobalMemoCell)
             memo: global_memo.clone(),
             mud: socket.clone(),
         };
-        handle_incoming_do(ctx, &mut mud_memo, &mud, &Telopt(optno));
+        if handle_incoming_do(ctx, &mut mud_memo, &mud, &Telopt(optno)) {
-        Ok(CallbackReturn::Return)
+            let seq = async_sequence(&ctx, move |locals, mut seq| {
+                let mud = locals.stash(&ctx, mud);
+                async move {
+                    let name =
+                        seq.try_enter(|ctx, _locals, _ex, _stack| Ok(name_telopt(ctx, optno)?))?;
+                    call_checking_metatable::<StashedTable, _>(
+                        &mut seq,
+                        mud,
+                        format!("local_{}_enabled", name),
+                        &[],
+                    )
+                    .await?;
+                    Ok(SequenceReturn::Return)
+                }
+            });
+            Ok(CallbackReturn::Sequence(seq))
+        } else {
+            Ok(CallbackReturn::Return)
+        }
     })
 }
 pub(super) fn mudoutput_dont<'gc>(
@@ -617,8 +682,13 @@ pub(super) fn new_mud<'gc>(ctx: Context<'gc>) -> Callback<'gc> {
             let mud = locals.stash(&ctx, mud);
 
             async move {
-                call_checking_metatable::<StashedTable>(&mut seq, frameroute, "new", &[curr_frame])
+                call_checking_metatable::<StashedTable, _>(
-                    .await?;
+                    &mut seq,
+                    frameroute,
+                    "new",
+                    &[curr_frame],
+                )
+                .await?;
                 seq.call(&create_match_tab, 0).await?;
 
                 seq.try_enter(|ctx, locals, _ex, mut stack| {
@@ -734,6 +804,73 @@ pub(super) fn mud_untrigger(ctx: Context<'_>) -> Callback<'_> {
     })
 }
 
+pub(super) fn mud_term_resized<'gc>(
+    ctx: Context<'gc>,
+    global_memo: &GlobalMemoCell,
+) -> Callback<'gc> {
+    let global_memo = global_memo.clone();
+    Callback::from_fn(&ctx, move |ctx, _ex, mut stack| {
+        let (mud, width, height): (Table, u16, u16) = stack.consume(ctx)?;
+        let socket: Value = mud.get(ctx, "socket")?;
+        let socket: &WebSocketId =
+            UserData::from_value(ctx, socket)?.downcast::<Rootable![Gc<'_, WebSocketId>]>()?;
+        send_subnegotiation_if_allowed(
+            ctx,
+            &mud,
+            &NAWS_TELOPT,
+            &Side::Us,
+            &mut MudWithMemo {
+                memo: global_memo.clone(),
+                mud: socket.clone(),
+            },
+            &[
+                (width >> 8) as u8,
+                (width & 0xFF) as u8,
+                (height >> 8) as u8,
+                (height & 0xFF) as u8,
+            ],
+        );
+        Ok(CallbackReturn::Return)
+    })
+}
+
+pub(super) fn local_naws_enabled<'gc>(
+    ctx: Context<'gc>,
+    global_state_memo: &GlobalMemoCell,
+) -> Callback<'gc> {
+    let global_state_memo = global_state_memo.clone();
+    Callback::from_fn(&ctx, move |ctx, _ex, mut stack| {
+        let mud: Table = stack.consume(ctx)?;
+        let frameroutes: Table = mud.get(ctx, "frameroutes")?;
+        let default_frame: FrameId = try_unwrap_frame(
+            ctx,
+            &frameroutes
+                .iter()
+                .map(|(_k, v)| Ok::<Table, Error>(Table::from_value(ctx, v)?))
+                .next()
+                .unwrap_or_else(|| Ok(ctx.get_global::<Table>("frames")?.get(ctx, 1_i64)?))?
+                .get(ctx, "frame")?,
+        )?;
+        let default_frame: Table = ctx
+            .get_global::<Table>("frames")?
+            .get(ctx, default_frame.0 as i64)?;
+        let width: Value = default_frame.get(ctx, "width")?;
+        let height: Value = default_frame.get(ctx, "height")?;
+        if width.is_nil() || height.is_nil() {
+            return Ok(CallbackReturn::Return);
+        }
+        stack.push_back(mud.into_value(ctx));
+        stack.push_back(width);
+        stack.push_back(height);
+        let cb = mud_term_resized(ctx, &global_state_memo);
+
+        Ok(CallbackReturn::Call {
+            function: Function::Callback(cb),
+            then: None,
+        })
+    })
+}
+
 fn name_mud<'gc>(ctx: Context<'gc>, mud: &Table<'gc>) -> String {
     fn name_mud_internal<'gc>(ctx: Context<'gc>, mud: &Table<'gc>) -> anyhow::Result<String> {
         let socket: Value<'gc> = mud.get(ctx, "socket")?;

src/lua_engine/muds/telopt.rs

@@ -4,7 +4,7 @@ use wasm_bindgen::JsValue;
 use web_sys::console;
 
 use crate::{
-    telnet::{DO, DONT, IAC, WILL, WONT},
+    telnet::{DO, DONT, ENDSUB, IAC, STARTSUB, WILL, WONT},
     websocket::{send_message_to_mud, WebSocketId},
     GlobalMemoCell,
 };
@@ -182,6 +182,29 @@ pub fn get_option_state<'gc>(
     }
 }
 
+pub fn send_subnegotiation_if_allowed<'gc, T: SendRaw>(
+    ctx: Context<'gc>,
+    mud_table: &Table<'gc>,
+    opt: &Telopt,
+    side: &Side,
+    mud: &mut T,
+    msg: &[u8],
+) {
+    if get_option_state(ctx, mud_table, opt, side) == OptionState::Yes {
+        let mut buf: Vec<u8> = Vec::with_capacity(msg.len() + 4);
+        buf.extend_from_slice(&[IAC, STARTSUB]);
+        for c in msg {
+            if *c == IAC {
+                buf.extend_from_slice(b"\xff\xff");
+            } else {
+                buf.push(*c);
+            }
+        }
+        buf.extend_from_slice(&[IAC, ENDSUB]);
+        mud.send_bytes(&buf);
+    }
+}
+
 pub fn set_option_state<'gc>(
     ctx: Context<'gc>,
     input: &Table<'gc>,
@@ -214,7 +237,7 @@ fn handle_incoming_positive<'gc, T: SendOptNeg>(
     mud: &mut T,
     table: &Table<'gc>,
     opt: &OptionWithActiveSide,
-) {
+) -> bool {
     match get_option_state(ctx, table, &opt.option, &opt.option_active_on) {
         OptionState::No => {
             if get_option_supported(ctx, table, &opt.option, &opt.option_active_on) {
@@ -226,6 +249,7 @@ fn handle_incoming_positive<'gc, T: SendOptNeg>(
                     &OptionState::Yes,
                 );
                 send_positive(mud, opt);
+                return true;
             } else {
                 send_negative(mud, opt);
             }
@@ -255,15 +279,19 @@ fn handle_incoming_positive<'gc, T: SendOptNeg>(
                 &opt.option,
                 &opt.option_active_on,
                 &OptionState::Yes,
-            )
+            );
+            return true;
+        }
+        OptionState::WantYes => {
+            set_option_state(
+                ctx,
+                table,
+                &opt.option,
+                &opt.option_active_on,
+                &OptionState::Yes,
+            );
+            return true;
         }
-        OptionState::WantYes => set_option_state(
-            ctx,
-            table,
-            &opt.option,
-            &opt.option_active_on,
-            &OptionState::Yes,
-        ),
         OptionState::WantYesOpposite => {
             set_option_state(
                 ctx,
@@ -275,6 +303,7 @@ fn handle_incoming_positive<'gc, T: SendOptNeg>(
             send_negative(mud, opt);
         }
     }
+    false
 }
 
 fn handle_incoming_negative<'gc, T: SendOptNeg>(
@@ -334,7 +363,7 @@ pub fn handle_incoming_will<'gc, T: SendOptNeg>(
     mud: &mut T,
     table: &Table<'gc>,
     option: &Telopt,
-) {
+) -> bool {
     handle_incoming_positive(
         ctx,
         mud,
@@ -343,7 +372,7 @@ pub fn handle_incoming_will<'gc, T: SendOptNeg>(
             option: option.clone(),
             option_active_on: Side::Him,
         },
-    );
+    )
 }
 
 pub fn handle_incoming_wont<'gc, T: SendOptNeg>(
@@ -368,7 +397,7 @@ pub fn handle_incoming_do<'gc, T: SendOptNeg>(
     mud: &mut T,
     table: &Table<'gc>,
     option: &Telopt,
-) {
+) -> bool {
     handle_incoming_positive(
         ctx,
         mud,
@@ -377,7 +406,7 @@ pub fn handle_incoming_do<'gc, T: SendOptNeg>(
             option: option.clone(),
             option_active_on: Side::Us,
         },
-    );
+    )
 }
 
 pub fn handle_incoming_dont<'gc, T: SendOptNeg>(
@@ -398,6 +427,7 @@ pub fn handle_incoming_dont<'gc, T: SendOptNeg>(
 }
 
 pub const GMCP_TELOPT: Telopt = Telopt(201);
+pub const NAWS_TELOPT: Telopt = Telopt(31);
 
 fn negotiate_option_on<'gc, T: SendOptNeg>(
     ctx: Context<'gc>,
@@ -487,6 +517,15 @@ pub fn negotiate_option<'gc, T: SendOptNeg>(
     }
 }
 
+pub fn configure_telopt_table<'gc>(ctx: Context<'gc>, table: &Table<'gc>) {
+    table
+        .set(ctx, "naws", NAWS_TELOPT.0)
+        .expect("Can't set NAWS in telopt table");
+    table
+        .set(ctx, "gmcp", GMCP_TELOPT.0)
+        .expect("Can't set GMCP in telopt table");
+}
+
 #[cfg(test)]
 mod tests {
     use piccolo::{Context, Lua, Table};

src/telnet.rs

@@ -29,8 +29,8 @@ const ERASECHAR: u8 = 247;
 const ERASELINE: u8 = 248;
 const GOAHEAD: u8 = 249;
 const EOR: u8 = 239;
-const STARTSUB: u8 = 250;
+pub const STARTSUB: u8 = 250;
-const ENDSUB: u8 = 240;
+pub const ENDSUB: u8 = 240;
 pub const WILL: u8 = 251;
 pub const WONT: u8 = 252;
 pub const DO: u8 = 253;
@@ -146,22 +146,22 @@ pub fn parse_telnet_buf(input: &[u8]) -> (Vec<u8>, Option<TelnetOutput>) {
                         }
                     }
                     Some(&STARTSUB) => {
-                        match (1..ptr.len() - 1).find(|i| ptr[*i] == IAC && ptr[*i + 1] == ENDSUB) {
+                        match try_parse_subneg(&ptr[1..]) {
                             None => {
                                 // Including the STARTSUB...
                                 textbuf.push(IAC);
                                 textbuf.extend_from_slice(ptr);
                                 return (textbuf, None);
                             }
-                            Some(end_idx) => {
+                            Some((subneg, new_ptr)) => {
-                                textbuf.extend_from_slice(&ptr[end_idx + 2..]);
+                                textbuf.extend_from_slice(new_ptr);
-                                return (
+                                return (textbuf, Some(TelnetOutput::Subnegotiation(subneg)));
-                                    textbuf,
-                                    Some(TelnetOutput::Subnegotiation(ptr[1..end_idx].to_owned())),
-                                );
                             }
                         }
                     }
+                    Some(&IAC) => {
+                        textbuf.push(IAC);
+                    }
                     Some(c) => {
                         // Completely unexpected command. Warn and ignore.
                         console::log_1(&JsValue::from_str(&format!(
@@ -177,6 +177,34 @@ pub fn parse_telnet_buf(input: &[u8]) -> (Vec<u8>, Option<TelnetOutput>) {
     }
 }
 
+fn try_parse_subneg(mut ptr: &[u8]) -> Option<(Vec<u8>, &[u8])> {
+    let mut subneg: Vec<u8> = Vec::new();
+    loop {
+        match ptr.first() {
+            None => return None,
+            Some(&IAC) => {
+                ptr = &ptr[1..];
+                match ptr.first() {
+                    None => return None,
+                    Some(&ENDSUB) => {
+                        ptr = &ptr[1..];
+                        return Some((subneg, ptr));
+                    }
+                    Some(c) => {
+                        // For c != IAC this is not expected.
+                        subneg.push(*c);
+                        ptr = &ptr[1..];
+                    }
+                }
+            }
+            Some(c) => {
+                subneg.push(*c);
+                ptr = &ptr[1..];
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -284,5 +312,12 @@ mod tests {
                 Some(TelnetOutput::Subnegotiation(b"blah".to_vec()))
             )
         );
+        assert_eq!(
+            parse_telnet_buf(b"Hello \xff\xfablah\xff\xff\xff\xf0World!"), // Partial subnegotiation
+            (
+                b"Hello World!".to_vec(),
+                Some(TelnetOutput::Subnegotiation(b"blah\xff".to_vec()))
+            )
+        );
     }
 }