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feat(caddy): add a WebSockets handler
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,144 @@ | ||
| // Copyright 2024 The Outline Authors | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 (the "License"); | ||
| // you may not use this file except in compliance with the License. | ||
| // You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, software | ||
| // distributed under the License is distributed on an "AS IS" BASIS, | ||
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
|
|
||
| package caddy | ||
|
|
||
| import ( | ||
| "errors" | ||
| "fmt" | ||
| "io" | ||
| "log/slog" | ||
| "net" | ||
| "net/http" | ||
| "time" | ||
|
|
||
| "github.com/Jigsaw-Code/outline-sdk/transport" | ||
| "github.com/caddyserver/caddy/v2" | ||
| "github.com/caddyserver/caddy/v2/modules/caddyhttp" | ||
| "golang.org/x/net/websocket" | ||
| ) | ||
|
|
||
| const wsModuleName = "http.handlers.websocket" | ||
|
|
||
| func init() { | ||
| caddy.RegisterModule(ModuleRegistration{ | ||
| ID: wsModuleName, | ||
| New: func() caddy.Module { return new(WebSocketHandler) }, | ||
| }) | ||
| } | ||
|
|
||
| // WebSocketHandler implements a middleware Caddy handler that proxies | ||
| // WebSockets connections. | ||
| type WebSocketHandler struct { | ||
| // The address of the backend to connect to. | ||
| Backend string `json:"backend,omitempty"` | ||
|
|
||
| logger *slog.Logger | ||
| } | ||
|
|
||
| var ( | ||
| _ caddy.Provisioner = (*WebSocketHandler)(nil) | ||
| _ caddy.Validator = (*WebSocketHandler)(nil) | ||
| _ caddyhttp.MiddlewareHandler = (*WebSocketHandler)(nil) | ||
| ) | ||
|
|
||
| func (*WebSocketHandler) CaddyModule() caddy.ModuleInfo { | ||
| return caddy.ModuleInfo{ID: wsModuleName} | ||
| } | ||
|
|
||
| // Provision implements caddy.Provisioner. | ||
| func (h *WebSocketHandler) Provision(ctx caddy.Context) error { | ||
| h.logger = ctx.Slogger() | ||
| return nil | ||
| } | ||
|
|
||
| // Validate implements caddy.Validator. | ||
| func (h *WebSocketHandler) Validate() error { | ||
| if h.Backend == "" { | ||
| return errors.New("must specify `backend`") | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // ServeHTTP implements caddyhttp.MiddlewareHandler. | ||
| func (h WebSocketHandler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error { | ||
| h.logger.Info("handling websocket connection", slog.String("path", r.URL.Path)) | ||
|
|
||
| backendAddr, err := caddy.ParseNetworkAddress(h.Backend) | ||
| if err != nil { | ||
| return fmt.Errorf("unable to parse `backend` network address: %v", err) | ||
| } | ||
|
|
||
| var handler func(wsConn *websocket.Conn) | ||
| switch backendAddr.Network { | ||
| case "tcp": | ||
| streamDialer := &transport.TCPDialer{} | ||
| endpoint := transport.StreamDialerEndpoint{Dialer: streamDialer, Address: backendAddr.JoinHostPort(0)} | ||
| handler = func(wsConn *websocket.Conn) { | ||
| targetConn, err := endpoint.ConnectStream(r.Context()) | ||
| if err != nil { | ||
| h.logger.Error("failed to connect to backend", slog.Any("err", err)) | ||
| w.WriteHeader(http.StatusBadGateway) | ||
| return | ||
| } | ||
| defer targetConn.Close() | ||
|
|
||
| go func() { | ||
| io.Copy(targetConn, wsConn) | ||
| targetConn.CloseWrite() | ||
| }() | ||
|
|
||
| io.Copy(wsConn, targetConn) | ||
| wsConn.Close() | ||
| } | ||
| case "udp": | ||
| packetDialer := &transport.UDPDialer{} | ||
| endpoint := transport.PacketDialerEndpoint{Dialer: packetDialer, Address: backendAddr.JoinHostPort(0)} | ||
| handler = func(wsConn *websocket.Conn) { | ||
| targetConn, err := endpoint.ConnectPacket(r.Context()) | ||
| if err != nil { | ||
| h.logger.Error("failed to connect to backend", slog.Any("err", err)) | ||
| w.WriteHeader(http.StatusBadGateway) | ||
| return | ||
| } | ||
| // Expire connection after 5 minutes of idle time, as per | ||
| // https://datatracker.ietf.org/doc/html/rfc4787#section-4.3 | ||
| targetConn = &natConn{targetConn, 5 * time.Minute} | ||
|
|
||
| go func() { | ||
| io.Copy(targetConn, wsConn) | ||
| targetConn.Close() | ||
| }() | ||
|
|
||
| io.Copy(wsConn, targetConn) | ||
| wsConn.Close() | ||
| } | ||
| default: | ||
| return fmt.Errorf("unsupported `backend` network: %v", backendAddr.Network) | ||
| } | ||
|
|
||
| websocket.Server{Handler: handler}.ServeHTTP(w, r) | ||
| return nil | ||
| } | ||
|
|
||
| type natConn struct { | ||
| net.Conn | ||
| mappingTimeout time.Duration | ||
| } | ||
|
|
||
| // Consider ReadFrom/WriteTo | ||
| func (c *natConn) Write(b []byte) (int, error) { | ||
| c.Conn.SetDeadline(time.Now().Add(c.mappingTimeout)) | ||
| return c.Conn.Write(b) | ||
| } |