github.com/sagernet/gvisor@v0.0.0-20240428053021-e691de28565f/pkg/tcpip/transport/udp/endpoint_state.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package udp
    16  
    17  import (
    18  	"context"
    19  	"fmt"
    20  	"time"
    21  
    22  	"github.com/sagernet/gvisor/pkg/tcpip"
    23  	"github.com/sagernet/gvisor/pkg/tcpip/stack"
    24  	"github.com/sagernet/gvisor/pkg/tcpip/transport"
    25  )
    26  
    27  // saveReceivedAt is invoked by stateify.
    28  func (p *udpPacket) saveReceivedAt() int64 {
    29  	return p.receivedAt.UnixNano()
    30  }
    31  
    32  // loadReceivedAt is invoked by stateify.
    33  func (p *udpPacket) loadReceivedAt(_ context.Context, nsec int64) {
    34  	p.receivedAt = time.Unix(0, nsec)
    35  }
    36  
    37  // afterLoad is invoked by stateify.
    38  func (e *endpoint) afterLoad(ctx context.Context) {
    39  	stack.RestoreStackFromContext(ctx).RegisterRestoredEndpoint(e)
    40  }
    41  
    42  // beforeSave is invoked by stateify.
    43  func (e *endpoint) beforeSave() {
    44  	e.freeze()
    45  	e.stack.RegisterResumableEndpoint(e)
    46  }
    47  
    48  // Restore implements tcpip.RestoredEndpoint.Restore.
    49  func (e *endpoint) Restore(s *stack.Stack) {
    50  	e.thaw()
    51  
    52  	e.mu.Lock()
    53  	defer e.mu.Unlock()
    54  
    55  	e.net.Resume(s)
    56  
    57  	e.stack = s
    58  	e.ops.InitHandler(e, e.stack, tcpip.GetStackSendBufferLimits, tcpip.GetStackReceiveBufferLimits)
    59  
    60  	switch state := e.net.State(); state {
    61  	case transport.DatagramEndpointStateInitial, transport.DatagramEndpointStateClosed:
    62  	case transport.DatagramEndpointStateBound, transport.DatagramEndpointStateConnected:
    63  		// Our saved state had a port, but we don't actually have a
    64  		// reservation. We need to remove the port from our state, but still
    65  		// pass it to the reservation machinery.
    66  		var err tcpip.Error
    67  		id := e.net.Info().ID
    68  		id.LocalPort = e.localPort
    69  		id.RemotePort = e.remotePort
    70  		id, e.boundBindToDevice, err = e.registerWithStack(e.effectiveNetProtos, id)
    71  		if err != nil {
    72  			panic(err)
    73  		}
    74  		e.localPort = id.LocalPort
    75  		e.remotePort = id.RemotePort
    76  	default:
    77  		panic(fmt.Sprintf("unhandled state = %s", state))
    78  	}
    79  }
    80  
    81  // Resume implements tcpip.ResumableEndpoint.Resume.
    82  func (e *endpoint) Resume() {
    83  	e.thaw()
    84  }