Add administrative unix listen endpoint

This adds support for listening on a Unix socket for administrative
connections, that then use a simple protocol for communicating with
the service (BouncerServ) as an administrator with a global context.

The wire format used by the Unix socket is IRC, but without
registration or overheads.

Example session:

    >>> BOUNCERSERV
    <<< 461 * BOUNCERSERV :Not enough parameters
    >>> BOUNCERSERV :n s
    <<< :gensou FAIL BOUNCERSERV :this command must be run as a user
    >>> BOUNCERSERV :u s
    <<< :gensou PRIVMSG * :marisa: 2 networks
    <<< :gensou PRIVMSG * :alice: 1 networks
    <<< :gensou BOUNCERSERV OK

cmd/soju/main.go

@@ -177,7 +177,7 @@ func main() {
 			ln := tls.NewListener(l, ircsTLSCfg)
 			ln = proxyProtoListener(ln, srv)
 			go func() {
-				if err := srv.Serve(ln); err != nil {
+				if err := srv.Serve(ln, srv.Handle); err != nil {
 					log.Printf("serving %q: %v", listen, err)
 				}
 			}()
@@ -195,7 +195,7 @@ func main() {
 			}
 			ln = proxyProtoListener(ln, srv)
 			go func() {
-				if err := srv.Serve(ln); err != nil {
+				if err := srv.Serve(ln, srv.Handle); err != nil {
 					log.Printf("serving %q: %v", listen, err)
 				}
 			}()
@@ -206,7 +206,22 @@ func main() {
 			}
 			ln = proxyProtoListener(ln, srv)
 			go func() {
-				if err := srv.Serve(ln); err != nil {
+				if err := srv.Serve(ln, srv.Handle); err != nil {
+					log.Printf("serving %q: %v", listen, err)
+				}
+			}()
+		case "unix+admin":
+			path := u.Path
+			if path == "" {
+				path = soju.DefaultUnixAdminPath
+			}
+			ln, err := net.Listen("unix", path)
+			if err != nil {
+				log.Fatalf("failed to start listener on %q: %v", listen, err)
+			}
+			ln = proxyProtoListener(ln, srv)
+			go func() {
+				if err := srv.Serve(ln, srv.HandleAdmin); err != nil {
 					log.Printf("serving %q: %v", listen, err)
 				}
 			}()

doc/soju.1.scd

@@ -85,7 +85,7 @@ The following directives are supported:
 	  omitted: 6697)
 	- _irc+insecure://[host][:port]_ listens with plain-text over TCP (default
 	  port if omitted: 6667)
-	- _unix:///<path>_ listens on a Unix domain socket
+	- _unix://<path>_ listens on a Unix domain socket
 	- _wss://[host][:port]_ listens for WebSocket connections over TLS (default
 	  port: 443)
 	- _ws+insecure://[host][:port]_ listens for plain-text WebSocket
@@ -97,6 +97,8 @@ The following directives are supported:
 	- _http+pprof://localhost:<port>_ listens for plain-text HTTP connections
 	  and serves pprof runtime profiling data (host must be "localhost"). For
 	  more information, see: <https://pkg.go.dev/net/http/pprof>.
+	- _unix+admin://[path]_ listens on a Unix domain socket for administrative
+	  connections, such as sojuctl (default path: /run/soju/admin)
 
 	If the scheme is omitted, "ircs" is assumed. If multiple *listen*
 	directives are specified, soju will listen on each of them.

server.go

@@ -26,6 +26,8 @@ import (
 	"git.sr.ht/~emersion/soju/identd"
 )
 
+var DefaultUnixAdminPath = "/run/soju/admin"
+
 // TODO: make configurable
 var retryConnectMinDelay = time.Minute
 var retryConnectMaxDelay = 10 * time.Minute
@@ -437,7 +439,7 @@ func (s *Server) addUserLocked(user *database.User) *user {
 
 var lastDownstreamID uint64
 
-func (s *Server) handle(ic ircConn) {
+func (s *Server) Handle(ic ircConn) {
 	defer func() {
 		if err := recover(); err != nil {
 			s.Logger.Printf("panic serving downstream %q: %v\n%v", ic.RemoteAddr(), err, string(debug.Stack()))
@@ -471,7 +473,91 @@ func (s *Server) handle(ic ircConn) {
 	s.metrics.downstreams.Add(-1)
 }
 
-func (s *Server) Serve(ln net.Listener) error {
+func (s *Server) HandleAdmin(ic ircConn) {
+	defer func() {
+		if err := recover(); err != nil {
+			s.Logger.Printf("panic serving admin client %q: %v\n%v", ic.RemoteAddr(), err, string(debug.Stack()))
+		}
+	}()
+
+	s.lock.Lock()
+	shutdown := s.shutdown
+	s.lock.Unlock()
+
+	ctx := context.TODO()
+	remoteAddr := ic.RemoteAddr().String()
+	logger := &prefixLogger{s.Logger, fmt.Sprintf("admin %q: ", remoteAddr)}
+	c := newConn(s, ic, &connOptions{Logger: logger})
+	defer c.Close()
+
+	if shutdown {
+		c.SendMessage(ctx, &irc.Message{
+			Command: "ERROR",
+			Params:  []string{"Server is shutting down"},
+		})
+		return
+	}
+	for {
+		msg, err := c.ReadMessage()
+		if errors.Is(err, io.EOF) {
+			break
+		} else if err != nil {
+			logger.Printf("failed to read IRC command: %v", err)
+			break
+		}
+		switch msg.Command {
+		case "BOUNCERSERV":
+			if len(msg.Params) < 1 {
+				c.SendMessage(ctx, &irc.Message{
+					Command: irc.ERR_NEEDMOREPARAMS,
+					Params: []string{
+						"*",
+						msg.Command,
+						"Not enough parameters",
+					},
+				})
+				break
+			}
+			err := handleServicePRIVMSG(&serviceContext{
+				Context: ctx,
+				srv:     s,
+				admin:   true,
+				print: func(text string) {
+					c.SendMessage(ctx, &irc.Message{
+						Prefix:  s.prefix(),
+						Command: "PRIVMSG",
+						Params:  []string{"*", text},
+					})
+				},
+			}, msg.Params[0])
+			if err != nil {
+				c.SendMessage(ctx, &irc.Message{
+					Prefix:  s.prefix(),
+					Command: "FAIL",
+					Params:  []string{msg.Command, err.Error()},
+				})
+			} else {
+				c.SendMessage(ctx, &irc.Message{
+					Prefix:  s.prefix(),
+					Command: msg.Command,
+					Params:  []string{"OK"},
+				})
+			}
+		default:
+			c.SendMessage(ctx, &irc.Message{
+				Prefix:  s.prefix(),
+				Command: irc.ERR_UNKNOWNCOMMAND,
+				Params: []string{
+					"*",
+					msg.Command,
+					"Unknown command",
+				},
+			})
+		}
+	}
+}
+
+func (s *Server) Serve(ln net.Listener, handler func(ircConn)) error {
 	ln = &retryListener{
 		Listener: ln,
 		Logger:   &prefixLogger{logger: s.Logger, prefix: fmt.Sprintf("listener %v: ", ln.Addr())},
@@ -499,7 +585,7 @@ func (s *Server) Serve(ln net.Listener) error {
 			return fmt.Errorf("failed to accept connection: %v", err)
 		}
 
-		go s.handle(newNetIRCConn(conn))
+		go handler(newNetIRCConn(conn))
 	}
 }
 
@@ -530,7 +616,7 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		}
 	}
 
-	s.handle(newWebsocketIRCConn(conn, remoteAddr))
+	s.Handle(newWebsocketIRCConn(conn, remoteAddr))
 }
 
 func parseForwarded(h http.Header) map[string]string {

server_test.go

@@ -61,7 +61,7 @@ func createTestUser(t *testing.T, db database.Database) *database.User {
 
 func createTestDownstream(t *testing.T, srv *Server) ircConn {
 	c1, c2 := net.Pipe()
-	go srv.handle(newNetIRCConn(c1))
+	go srv.Handle(newNetIRCConn(c1))
 	return newNetIRCConn(c2)
 }