snapshot: sagernet/gvisor v0.0.0-20250811.0-sing-box-mod.1

Содержимое пина, зафиксированного в go.mod sing-box-lx, одним коммитом
без истории. Полная история SagerNet/gvisor — 1.45 ГБ и клонируется в
каждой CI-джобе; наша дельта — одна вставка в одну функцию, история для
неё не нужна.

Module path github.com/sagernet/gvisor сохранён намеренно: на него
опирается replace-директива суперпроекта.

Патч поверх — отдельным коммитом, чтобы дельта читалась одним git show
и переносилась на новый пин копированием.

SPECS/TASKS/048-GVISOR_HANDSHAKE_NIL_CRASH

pkg/tcpip/transport/udp/forwarder.go

@@ -0,0 +1,112 @@
+// Copyright 2019 The gVisor 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 udp
+
+import (
+	"github.com/sagernet/gvisor/pkg/tcpip"
+	"github.com/sagernet/gvisor/pkg/tcpip/stack"
+	"github.com/sagernet/gvisor/pkg/waiter"
+)
+
+// ForwarderHandler handles incoming requests. Returning true marks the
+// request as handled, returning false marks the request as unhandled.
+// Stack may send an ICMP port unreachable message for unhandled requests.
+type ForwarderHandler func(*ForwarderRequest) (handled bool)
+
+// Forwarder is a session request forwarder, which allows clients to decide
+// what to do with a session request, for example: ignore it, or process it.
+//
+// The canonical way of using it is to pass the Forwarder.HandlePacket function
+// to stack.SetTransportProtocolHandler.
+type Forwarder struct {
+	handler ForwarderHandler
+
+	stack *stack.Stack
+}
+
+// NewForwarder allocates and initializes a new forwarder.
+func NewForwarder(s *stack.Stack, handler ForwarderHandler) *Forwarder {
+	return &Forwarder{
+		stack:   s,
+		handler: handler,
+	}
+}
+
+// HandlePacket handles all packets.
+//
+// This function is expected to be passed as an argument to the
+// stack.SetTransportProtocolHandler function.
+func (f *Forwarder) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketBuffer) bool {
+	return f.handler(&ForwarderRequest{
+		stack: f.stack,
+		id:    id,
+		pkt:   pkt.Clone(),
+	})
+}
+
+// ForwarderRequest represents a session request received by the forwarder and
+// passed to the client. Clients may optionally create an endpoint to represent
+// it via CreateEndpoint.
+type ForwarderRequest struct {
+	stack *stack.Stack
+	id    stack.TransportEndpointID
+	pkt   *stack.PacketBuffer
+}
+
+// ID returns the 4-tuple (src address, src port, dst address, dst port) that
+// represents the session request.
+func (r *ForwarderRequest) ID() stack.TransportEndpointID {
+	return r.id
+}
+
+// CreateEndpoint creates a connected UDP endpoint for the session request.
+func (r *ForwarderRequest) CreateEndpoint(queue *waiter.Queue) (tcpip.Endpoint, tcpip.Error) {
+	ep := newEndpoint(r.stack, r.pkt.NetworkProtocolNumber, queue)
+	ep.mu.Lock()
+	defer ep.mu.Unlock()
+
+	netHdr := r.pkt.Network()
+	if err := ep.net.Bind(tcpip.FullAddress{NIC: r.pkt.NICID, Addr: netHdr.DestinationAddress(), Port: r.id.LocalPort}); err != nil {
+		ep.closeLocked()
+		return nil, err
+	}
+
+	if err := ep.net.Connect(tcpip.FullAddress{NIC: r.pkt.NICID, Addr: netHdr.SourceAddress(), Port: r.id.RemotePort}); err != nil {
+		ep.closeLocked()
+		return nil, err
+	}
+
+	if err := r.stack.RegisterTransportEndpoint([]tcpip.NetworkProtocolNumber{r.pkt.NetworkProtocolNumber}, ProtocolNumber, r.id, ep, ep.portFlags, tcpip.NICID(ep.ops.GetBindToDevice())); err != nil {
+		ep.closeLocked()
+		return nil, err
+	}
+
+	ep.localPort = r.id.LocalPort
+	ep.remotePort = r.id.RemotePort
+	ep.effectiveNetProtos = []tcpip.NetworkProtocolNumber{r.pkt.NetworkProtocolNumber}
+	ep.boundPortFlags = ep.portFlags
+
+	ep.rcvMu.Lock()
+	ep.rcvReady = true
+	ep.rcvMu.Unlock()
+
+	ep.HandlePacket(r.id, r.pkt)
+
+	return ep, nil
+}
+
+func (r *ForwarderRequest) Packet() *stack.PacketBuffer {
+	return r.pkt
+}