Multi-client servers + bring back stdinserver support

daemon/serve/serve.go

@@ -6,10 +6,69 @@ import (
 	"net"
 	"github.com/zrepl/zrepl/daemon/streamrpcconfig"
 	"github.com/problame/go-streamrpc"
+	"context"
+	"github.com/zrepl/zrepl/logger"
+	"github.com/zrepl/zrepl/zfs"
 )
 
+type contextKey int
+
+const contextKeyLog contextKey = 0
+
+type Logger = logger.Logger
+
+func WithLogger(ctx context.Context, log Logger) context.Context {
+	return context.WithValue(ctx, contextKeyLog, log)
+}
+
+func getLogger(ctx context.Context) Logger {
+	if log, ok := ctx.Value(contextKeyLog).(Logger); ok {
+		return log
+	}
+	return logger.NewNullLogger()
+}
+
+type AuthenticatedConn interface {
+	net.Conn
+	// ClientIdentity must be a string that satisfies ValidateClientIdentity
+	ClientIdentity() string
+}
+
+// A client identity must be a single component in a ZFS filesystem path
+func ValidateClientIdentity(in string) (err error) {
+	path, err := zfs.NewDatasetPath(in)
+	if err != nil {
+		return err
+	}
+	if path.Length() != 1 {
+		return errors.New("client identity must be a single path comonent (not empty, no '/')")
+	}
+	return nil
+}
+
+type authConn struct {
+	net.Conn
+	clientIdentity string
+}
+
+var _ AuthenticatedConn = authConn{}
+
+func (c authConn) ClientIdentity() string {
+	if err := ValidateClientIdentity(c.clientIdentity); err != nil {
+		panic(err)
+	}
+	return c.clientIdentity
+}
+
+// like net.Listener, but with an AuthenticatedConn instead of net.Conn
+type AuthenticatedListener interface {
+	Addr() (net.Addr)
+	Accept(ctx context.Context) (AuthenticatedConn, error)
+	Close() error
+}
+
 type ListenerFactory interface {
-	Listen() (net.Listener, error)
+	Listen() (AuthenticatedListener, error)
 }
 
 func FromConfig(g *config.Global, in config.ServeEnum) (lf ListenerFactory, conf *streamrpc.ConnConfig, _ error) {
@@ -25,7 +84,7 @@ func FromConfig(g *config.Global, in config.ServeEnum) (lf ListenerFactory, conf
 		lf, lfError = TLSListenerFactoryFromConfig(g, v)
 		conf, rpcErr = streamrpcconfig.FromDaemonConfig(g, v.RPC)
 	case *config.StdinserverServer:
-		lf, lfError = StdinserverListenerFactoryFromConfig(g, v)
+		lf, lfError = MultiStdinserverListenerFactoryFromConfig(g, v)
 		conf, rpcErr = streamrpcconfig.FromDaemonConfig(g, v.RPC)
 	default:
 		return nil, nil, errors.Errorf("internal error: unknown serve type %T", v)