// Copyright 2016 The Netstack Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package udp

import (
	"gvisor.googlesource.com/gvisor/pkg/tcpip"
	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
	"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
	"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
)

// saveData saves udpPacket.data field.
func (u *udpPacket) saveData() buffer.VectorisedView {
	// We canoot save u.data directly as u.data.views may alias to u.views,
	// which is not allowed by state framework (in-struct pointer).
	return u.data.Clone(nil)
}

// loadData loads udpPacket.data field.
func (u *udpPacket) loadData(data buffer.VectorisedView) {
	// NOTE: We cannot do the u.data = data.Clone(u.views[:]) optimization
	// here because data.views is not guaranteed to be loaded by now. Plus,
	// data.views will be allocated anyway so there really is little point
	// of utilizing u.views for data.views.
	u.data = data
}

// beforeSave is invoked by stateify.
func (e *endpoint) beforeSave() {
	// Stop incoming packets from being handled (and mutate endpoint state).
	// The lock will be released after savercvBufSizeMax(), which would have
	// saved e.rcvBufSizeMax and set it to 0 to continue blocking incoming
	// packets.
	e.rcvMu.Lock()
}

// saveRcvBufSizeMax is invoked by stateify.
func (e *endpoint) saveRcvBufSizeMax() int {
	max := e.rcvBufSizeMax
	// Make sure no new packets will be handled regardless of the lock.
	e.rcvBufSizeMax = 0
	// Release the lock acquired in beforeSave() so regular endpoint closing
	// logic can proceed after save.
	e.rcvMu.Unlock()
	return max
}

// loadRcvBufSizeMax is invoked by stateify.
func (e *endpoint) loadRcvBufSizeMax(max int) {
	e.rcvBufSizeMax = max
}

// afterLoad is invoked by stateify.
func (e *endpoint) afterLoad() {
	e.stack = stack.StackFromEnv

	if e.state != stateBound && e.state != stateConnected {
		return
	}

	netProto := e.effectiveNetProtos[0]
	// Connect() and bindLocked() both assert
	//
	//     netProto == header.IPv6ProtocolNumber
	//
	// before creating a multi-entry effectiveNetProtos.
	if len(e.effectiveNetProtos) > 1 {
		netProto = header.IPv6ProtocolNumber
	}

	var err *tcpip.Error
	if e.state == stateConnected {
		e.route, err = e.stack.FindRoute(e.regNICID, e.bindAddr, e.id.RemoteAddress, netProto)
		if err != nil {
			panic(*err)
		}

		e.id.LocalAddress = e.route.LocalAddress
	} else if len(e.id.LocalAddress) != 0 { // stateBound
		if e.stack.CheckLocalAddress(e.regNICID, netProto, e.id.LocalAddress) == 0 {
			panic(tcpip.ErrBadLocalAddress)
		}
	}

	e.id, err = e.registerWithStack(e.regNICID, e.effectiveNetProtos, e.id)
	if err != nil {
		panic(*err)
	}
}