Reconnect once if hysteria request fails

This allows graceful recovery when network isn't good enough.

[Original hysteria source
code](https://github.com/apernet/hysteria/blob/13d46da99876c2c9feb1083ff5f2da201d9d0a1e/core/cs/client.go#L182)
has similar mechanism.

outbound/hysteria.go

@@ -150,6 +150,7 @@ func (h *Hysteria) offer(ctx context.Context) (quic.Connection, error) {
 	if conn != nil && !common.Done(conn.Context()) {
 		return conn, nil
 	}
+	common.Close(h.rawConn)
 	conn, err := h.offerNew(ctx)
 	if err != nil {
 		return nil, err
@@ -260,14 +261,18 @@ func (h *Hysteria) Close() error {
 	return nil
 }
 
-func (h *Hysteria) open(ctx context.Context) (quic.Connection, quic.Stream, error) {
+func (h *Hysteria) open(ctx context.Context, reconnect bool) (quic.Connection, quic.Stream, error) {
 	conn, err := h.offer(ctx)
 	if err != nil {
-		return nil, nil, err
+		if nErr, ok := err.(net.Error); ok && !nErr.Temporary() && reconnect {
+			return h.open(ctx, false)
+		}
 	}
 	stream, err := conn.OpenStream()
 	if err != nil {
-		return nil, nil, err
+		if nErr, ok := err.(net.Error); ok && !nErr.Temporary() && reconnect {
+			return h.open(ctx, false)
+		}
 	}
 	return conn, &hysteria.StreamWrapper{Stream: stream}, nil
 }
@@ -276,7 +281,7 @@ func (h *Hysteria) DialContext(ctx context.Context, network string, destination
 	switch N.NetworkName(network) {
 	case N.NetworkTCP:
 		h.logger.InfoContext(ctx, "outbound connection to ", destination)
-		_, stream, err := h.open(ctx)
+		_, stream, err := h.open(ctx, true)
 		if err != nil {
 			return nil, err
 		}
@@ -302,7 +307,7 @@ func (h *Hysteria) DialContext(ctx context.Context, network string, destination
 
 func (h *Hysteria) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
 	h.logger.InfoContext(ctx, "outbound packet connection to ", destination)
-	conn, stream, err := h.open(ctx)
+	conn, stream, err := h.open(ctx, true)
 	if err != nil {
 		return nil, err
 	}