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// Copyright 2020 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 tcpip
import (
"sync/atomic"
)
// SocketOptionsHandler holds methods that help define endpoint specific
// behavior for socket options.
// These must be implemented by endpoints to:
// - Get notified when socket level options are set.
// - Provide endpoint specific socket options.
type SocketOptionsHandler interface {
// OnReuseAddressSet is invoked when SO_REUSEADDR is set for an endpoint.
OnReuseAddressSet(v bool)
// OnReusePortSet is invoked when SO_REUSEPORT is set for an endpoint.
OnReusePortSet(v bool)
// OnKeepAliveSet is invoked when SO_KEEPALIVE is set for an endpoint.
OnKeepAliveSet(v bool)
// IsListening is invoked to fetch SO_ACCEPTCONN option value for an
// endpoint. It is used to indicate if the socket is a listening socket.
IsListening() bool
}
// DefaultSocketOptionsHandler is an embeddable type that implements no-op
// implementations for SocketOptionsHandler methods.
type DefaultSocketOptionsHandler struct{}
var _ SocketOptionsHandler = (*DefaultSocketOptionsHandler)(nil)
// OnReuseAddressSet implements SocketOptionsHandler.OnReuseAddressSet.
func (*DefaultSocketOptionsHandler) OnReuseAddressSet(bool) {}
// OnReusePortSet implements SocketOptionsHandler.OnReusePortSet.
func (*DefaultSocketOptionsHandler) OnReusePortSet(bool) {}
// OnKeepAliveSet implements SocketOptionsHandler.OnKeepAliveSet.
func (*DefaultSocketOptionsHandler) OnKeepAliveSet(bool) {}
// IsListening implements SocketOptionsHandler.IsListening.
func (*DefaultSocketOptionsHandler) IsListening() bool { return false }
// SocketOptions contains all the variables which store values for SOL_SOCKET
// level options.
//
// +stateify savable
type SocketOptions struct {
handler SocketOptionsHandler
// These fields are accessed and modified using atomic operations.
// broadcastEnabled determines whether datagram sockets are allowed to send
// packets to a broadcast address.
broadcastEnabled uint32
// passCredEnabled determines whether SCM_CREDENTIALS socket control messages
// are enabled.
passCredEnabled uint32
// noChecksumEnabled determines whether UDP checksum is disabled while
// transmitting for this socket.
noChecksumEnabled uint32
// reuseAddressEnabled determines whether Bind() should allow reuse of local
// address.
reuseAddressEnabled uint32
// reusePortEnabled determines whether to permit multiple sockets to be bound
// to an identical socket address.
reusePortEnabled uint32
// keepAliveEnabled determines whether TCP keepalive is enabled for this
// socket.
keepAliveEnabled uint32
}
// InitHandler initializes the handler. This must be called before using the
// socket options utility.
func (so *SocketOptions) InitHandler(handler SocketOptionsHandler) {
so.handler = handler
}
func storeAtomicBool(addr *uint32, v bool) {
var val uint32
if v {
val = 1
}
atomic.StoreUint32(addr, val)
}
// GetBroadcast gets value for SO_BROADCAST option.
func (so *SocketOptions) GetBroadcast() bool {
return atomic.LoadUint32(&so.broadcastEnabled) != 0
}
// SetBroadcast sets value for SO_BROADCAST option.
func (so *SocketOptions) SetBroadcast(v bool) {
storeAtomicBool(&so.broadcastEnabled, v)
}
// GetPassCred gets value for SO_PASSCRED option.
func (so *SocketOptions) GetPassCred() bool {
return atomic.LoadUint32(&so.passCredEnabled) != 0
}
// SetPassCred sets value for SO_PASSCRED option.
func (so *SocketOptions) SetPassCred(v bool) {
storeAtomicBool(&so.passCredEnabled, v)
}
// GetNoChecksum gets value for SO_NO_CHECK option.
func (so *SocketOptions) GetNoChecksum() bool {
return atomic.LoadUint32(&so.noChecksumEnabled) != 0
}
// SetNoChecksum sets value for SO_NO_CHECK option.
func (so *SocketOptions) SetNoChecksum(v bool) {
storeAtomicBool(&so.noChecksumEnabled, v)
}
// GetReuseAddress gets value for SO_REUSEADDR option.
func (so *SocketOptions) GetReuseAddress() bool {
return atomic.LoadUint32(&so.reuseAddressEnabled) != 0
}
// SetReuseAddress sets value for SO_REUSEADDR option.
func (so *SocketOptions) SetReuseAddress(v bool) {
storeAtomicBool(&so.reuseAddressEnabled, v)
so.handler.OnReuseAddressSet(v)
}
// GetReusePort gets value for SO_REUSEPORT option.
func (so *SocketOptions) GetReusePort() bool {
return atomic.LoadUint32(&so.reusePortEnabled) != 0
}
// SetReusePort sets value for SO_REUSEPORT option.
func (so *SocketOptions) SetReusePort(v bool) {
storeAtomicBool(&so.reusePortEnabled, v)
so.handler.OnReusePortSet(v)
}
// GetKeepAlive gets value for SO_KEEPALIVE option.
func (so *SocketOptions) GetKeepAlive() bool {
return atomic.LoadUint32(&so.keepAliveEnabled) != 0
}
// SetKeepAlive sets value for SO_KEEPALIVE option.
func (so *SocketOptions) SetKeepAlive(v bool) {
storeAtomicBool(&so.keepAliveEnabled, v)
so.handler.OnKeepAliveSet(v)
}
// GetAcceptConn gets value for SO_ACCEPTCONN option.
func (so *SocketOptions) GetAcceptConn() bool {
// This option is completely endpoint dependent and unsettable.
return so.handler.IsListening()
}
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