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/header/virtionet.go

@@ -0,0 +1,94 @@
+// Copyright 2021 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 header
+
+import "encoding/binary"
+
+// These constants are declared in linux/virtio_net.h.
+const (
+	_VIRTIO_NET_HDR_F_NEEDS_CSUM = 1
+	_VIRTIO_NET_HDR_GSO_NONE     = 0
+	_VIRTIO_NET_HDR_GSO_TCPV4    = 1
+	_VIRTIO_NET_HDR_GSO_TCPV6    = 4
+)
+
+const (
+	// VirtioNetHeaderSize is the size of VirtioNetHeader in bytes.
+	VirtioNetHeaderSize = 10
+)
+
+// Offsets for fields in the virtio net header.
+const (
+	flags      = 0
+	gsoType    = 1
+	hdrLen     = 2
+	gsoSize    = 4
+	csumStart  = 6
+	csumOffset = 8
+)
+
+// VirtioNetHeaderFields is the Go equivalent of the struct declared in
+// linux/virtio_net.h.
+type VirtioNetHeaderFields struct {
+	Flags      uint8
+	GSOType    uint8
+	HdrLen     uint16
+	GSOSize    uint16
+	CSumStart  uint16
+	CSumOffset uint16
+}
+
+// VirtioNetHeader represents a virtio net header stored in a byte array.
+type VirtioNetHeader []byte
+
+// Flags returns the "flags" field of the virtio net header.
+func (v VirtioNetHeader) Flags() uint8 {
+	return uint8(v[flags])
+}
+
+// GSOType returns the "gsoType" field of the virtio net header.
+func (v VirtioNetHeader) GSOType() uint8 {
+	return uint8(v[gsoType])
+}
+
+// HdrLen returns the "hdrLen" field of the virtio net header.
+func (v VirtioNetHeader) HdrLen() uint16 {
+	return binary.BigEndian.Uint16(v[hdrLen:])
+}
+
+// GSOSize returns the "gsoSize" field of the virtio net header.
+func (v VirtioNetHeader) GSOSize() uint16 {
+	return binary.BigEndian.Uint16(v[gsoSize:])
+}
+
+// CSumStart returns the "csumStart" field of the virtio net header.
+func (v VirtioNetHeader) CSumStart() uint16 {
+	return binary.BigEndian.Uint16(v[csumStart:])
+}
+
+// CSumOffset returns the "csumOffset" field of the virtio net header.
+func (v VirtioNetHeader) CSumOffset() uint16 {
+	return binary.BigEndian.Uint16(v[csumOffset:])
+}
+
+// Encode encodes all the fields of the virtio net header.
+func (v VirtioNetHeader) Encode(f *VirtioNetHeaderFields) {
+	v[flags] = uint8(f.Flags)
+	v[gsoType] = uint8(f.GSOType)
+	binary.LittleEndian.PutUint16(v[hdrLen:], f.HdrLen)
+	binary.LittleEndian.PutUint16(v[gsoSize:], f.GSOSize)
+	binary.LittleEndian.PutUint16(v[csumStart:], f.CSumStart)
+	binary.LittleEndian.PutUint16(v[csumOffset:], f.CSumOffset)
+}