fix(lsp): stop repeatedly resuming dead coroutine #35743

Problem:
Error extracting content-length causes all future coroutine resumes to
fail.

Solution:
Replace coroutine.wrap with coroutine.create in create_read_loop
so that we can check its status and catch any errors, allowing us to
stop the lsp client and avoid repeatedly resuming the dead coroutine.

runtime/lua/vim/lsp/rpc.lua

@@ -175,27 +175,34 @@ end
 --- @private
 --- @param handle_body fun(body: string)
 --- @param on_exit? fun()
---- @param on_error fun(err: any)
+--- @param on_error? fun(err: any, errkind: vim.lsp.rpc.ClientErrors)
 function M.create_read_loop(handle_body, on_exit, on_error)
-  local parse_chunk = coroutine.wrap(request_parser_loop) --[[@as fun(chunk: string?): string]]
-  parse_chunk()
+  on_exit = on_exit or function() end
+  on_error = on_error or function() end
+  local co = coroutine.create(request_parser_loop)
+  coroutine.resume(co)
   return function(err, chunk)
     if err then
-      on_error(err)
+      on_error(err, M.client_errors.READ_ERROR)
       return
     end
 
     if not chunk then
-      if on_exit then
-        on_exit()
-      end
+      on_exit()
+      return
+    end
+
+    if coroutine.status(co) == 'dead' then
       return
     end
 
     while true do
-      local body = parse_chunk(chunk)
-      if body then
-        handle_body(body)
+      local ok, res = coroutine.resume(co, chunk)
+      if not ok then
+        on_error(res, M.client_errors.INVALID_SERVER_MESSAGE)
+        break
+      elseif res then
+        handle_body(res)
         chunk = ''
       else
         break
@@ -547,8 +554,12 @@ local function create_client_read_loop(client, on_exit)
     client:handle_body(body)
   end
 
-  local function on_error(err)
-    client:on_error(M.client_errors.READ_ERROR, err)
+  --- @param errkind vim.lsp.rpc.ClientErrors
+  local function on_error(err, errkind)
+    client:on_error(errkind, err)
+    if errkind == M.client_errors.INVALID_SERVER_MESSAGE then
+      client.transport:terminate()
+    end
   end
 
   return M.create_read_loop(handle_body, on_exit, on_error)

test/functional/plugin/lsp_spec.lua

@@ -1971,6 +1971,43 @@ describe('LSP', function()
       }
     end)
 
+    it('should catch error while parsing invalid header', function()
+      local header = 'Content-Length: \r\n'
+      local called = false
+      exec_lua(function()
+        local server = assert(vim.uv.new_tcp())
+        server:bind('127.0.0.1', 0)
+        server:listen(1, function(e)
+          assert(not e, e)
+          local socket = assert(vim.uv.new_tcp())
+          server:accept(socket)
+          socket:write(header .. '\r\n', function()
+            socket:shutdown()
+            server:close()
+          end)
+        end)
+        local client = assert(vim.uv.new_tcp())
+        local on_read = require('vim.lsp.rpc').create_read_loop(function() end, function()
+          client:close()
+        end, function(err, code)
+          vim.rpcnotify(1, 'error', err, code)
+        end)
+        client:connect('127.0.0.1', server:getsockname().port, function()
+          client:read_start(on_read)
+        end)
+      end)
+      n.run(nil, function(method, args)
+        local err, code = unpack(args) --- @type string, number
+        eq('error', method)
+        eq(1, code)
+        matches(vim.pesc('Content-Length not found in header: ' .. header) .. '$', err)
+        called = true
+        stop()
+        return NIL
+      end, nil, 1000)
+      eq(true, called)
+    end)
+
     it('should not trim vim.NIL from the end of a list', function()
       local expected_handlers = {
         { NIL, {}, { method = 'shutdown', client_id = 1 } },