mirror of
https://git.zx2c4.com/wireguard-go
synced 2024-11-15 01:05:15 +01:00
295 lines
6.6 KiB
Go
295 lines
6.6 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2022 WireGuard LLC. All Rights Reserved.
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*/
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package device
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import (
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"container/list"
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"encoding/binary"
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"errors"
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"math/bits"
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"net"
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"net/netip"
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"sync"
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"unsafe"
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)
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type parentIndirection struct {
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parentBit **trieEntry
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parentBitType uint8
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}
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type trieEntry struct {
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peer *Peer
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child [2]*trieEntry
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parent parentIndirection
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cidr uint8
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bitAtByte uint8
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bitAtShift uint8
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bits []byte
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perPeerElem *list.Element
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}
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func commonBits(ip1, ip2 []byte) uint8 {
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size := len(ip1)
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if size == net.IPv4len {
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a := binary.BigEndian.Uint32(ip1)
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b := binary.BigEndian.Uint32(ip2)
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x := a ^ b
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return uint8(bits.LeadingZeros32(x))
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} else if size == net.IPv6len {
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a := binary.BigEndian.Uint64(ip1)
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b := binary.BigEndian.Uint64(ip2)
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x := a ^ b
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if x != 0 {
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return uint8(bits.LeadingZeros64(x))
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}
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a = binary.BigEndian.Uint64(ip1[8:])
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b = binary.BigEndian.Uint64(ip2[8:])
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x = a ^ b
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return 64 + uint8(bits.LeadingZeros64(x))
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} else {
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panic("Wrong size bit string")
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}
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}
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func (node *trieEntry) addToPeerEntries() {
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node.perPeerElem = node.peer.trieEntries.PushBack(node)
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}
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func (node *trieEntry) removeFromPeerEntries() {
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if node.perPeerElem != nil {
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node.peer.trieEntries.Remove(node.perPeerElem)
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node.perPeerElem = nil
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}
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}
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func (node *trieEntry) choose(ip []byte) byte {
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return (ip[node.bitAtByte] >> node.bitAtShift) & 1
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}
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func (node *trieEntry) maskSelf() {
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mask := net.CIDRMask(int(node.cidr), len(node.bits)*8)
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for i := 0; i < len(mask); i++ {
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node.bits[i] &= mask[i]
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}
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}
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func (node *trieEntry) zeroizePointers() {
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// Make the garbage collector's life slightly easier
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node.peer = nil
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node.child[0] = nil
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node.child[1] = nil
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node.parent.parentBit = nil
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}
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func (node *trieEntry) nodePlacement(ip []byte, cidr uint8) (parent *trieEntry, exact bool) {
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for node != nil && node.cidr <= cidr && commonBits(node.bits, ip) >= node.cidr {
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parent = node
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if parent.cidr == cidr {
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exact = true
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return
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}
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bit := node.choose(ip)
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node = node.child[bit]
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}
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return
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}
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func (trie parentIndirection) insert(ip []byte, cidr uint8, peer *Peer) {
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if *trie.parentBit == nil {
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node := &trieEntry{
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peer: peer,
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parent: trie,
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bits: ip,
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cidr: cidr,
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bitAtByte: cidr / 8,
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bitAtShift: 7 - (cidr % 8),
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}
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node.maskSelf()
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node.addToPeerEntries()
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*trie.parentBit = node
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return
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}
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node, exact := (*trie.parentBit).nodePlacement(ip, cidr)
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if exact {
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node.removeFromPeerEntries()
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node.peer = peer
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node.addToPeerEntries()
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return
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}
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newNode := &trieEntry{
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peer: peer,
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bits: ip,
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cidr: cidr,
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bitAtByte: cidr / 8,
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bitAtShift: 7 - (cidr % 8),
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}
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newNode.maskSelf()
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newNode.addToPeerEntries()
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var down *trieEntry
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if node == nil {
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down = *trie.parentBit
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} else {
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bit := node.choose(ip)
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down = node.child[bit]
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if down == nil {
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newNode.parent = parentIndirection{&node.child[bit], bit}
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node.child[bit] = newNode
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return
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}
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}
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common := commonBits(down.bits, ip)
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if common < cidr {
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cidr = common
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}
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parent := node
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if newNode.cidr == cidr {
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bit := newNode.choose(down.bits)
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down.parent = parentIndirection{&newNode.child[bit], bit}
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newNode.child[bit] = down
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if parent == nil {
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newNode.parent = trie
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*trie.parentBit = newNode
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} else {
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bit := parent.choose(newNode.bits)
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newNode.parent = parentIndirection{&parent.child[bit], bit}
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parent.child[bit] = newNode
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}
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return
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}
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node = &trieEntry{
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bits: append([]byte{}, newNode.bits...),
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cidr: cidr,
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bitAtByte: cidr / 8,
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bitAtShift: 7 - (cidr % 8),
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}
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node.maskSelf()
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bit := node.choose(down.bits)
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down.parent = parentIndirection{&node.child[bit], bit}
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node.child[bit] = down
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bit = node.choose(newNode.bits)
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newNode.parent = parentIndirection{&node.child[bit], bit}
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node.child[bit] = newNode
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if parent == nil {
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node.parent = trie
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*trie.parentBit = node
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} else {
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bit := parent.choose(node.bits)
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node.parent = parentIndirection{&parent.child[bit], bit}
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parent.child[bit] = node
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}
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}
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func (node *trieEntry) lookup(ip []byte) *Peer {
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var found *Peer
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size := uint8(len(ip))
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for node != nil && commonBits(node.bits, ip) >= node.cidr {
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if node.peer != nil {
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found = node.peer
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}
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if node.bitAtByte == size {
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break
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}
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bit := node.choose(ip)
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node = node.child[bit]
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}
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return found
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}
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type AllowedIPs struct {
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IPv4 *trieEntry
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IPv6 *trieEntry
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mutex sync.RWMutex
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}
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func (table *AllowedIPs) EntriesForPeer(peer *Peer, cb func(prefix netip.Prefix) bool) {
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table.mutex.RLock()
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defer table.mutex.RUnlock()
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for elem := peer.trieEntries.Front(); elem != nil; elem = elem.Next() {
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node := elem.Value.(*trieEntry)
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a, _ := netip.AddrFromSlice(node.bits)
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if !cb(netip.PrefixFrom(a, int(node.cidr))) {
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return
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}
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}
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}
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func (table *AllowedIPs) RemoveByPeer(peer *Peer) {
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table.mutex.Lock()
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defer table.mutex.Unlock()
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var next *list.Element
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for elem := peer.trieEntries.Front(); elem != nil; elem = next {
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next = elem.Next()
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node := elem.Value.(*trieEntry)
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node.removeFromPeerEntries()
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node.peer = nil
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if node.child[0] != nil && node.child[1] != nil {
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continue
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}
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bit := 0
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if node.child[0] == nil {
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bit = 1
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}
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child := node.child[bit]
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if child != nil {
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child.parent = node.parent
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}
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*node.parent.parentBit = child
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if node.child[0] != nil || node.child[1] != nil || node.parent.parentBitType > 1 {
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node.zeroizePointers()
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continue
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}
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parent := (*trieEntry)(unsafe.Pointer(uintptr(unsafe.Pointer(node.parent.parentBit)) - unsafe.Offsetof(node.child) - unsafe.Sizeof(node.child[0])*uintptr(node.parent.parentBitType)))
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if parent.peer != nil {
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node.zeroizePointers()
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continue
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}
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child = parent.child[node.parent.parentBitType^1]
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if child != nil {
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child.parent = parent.parent
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}
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*parent.parent.parentBit = child
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node.zeroizePointers()
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parent.zeroizePointers()
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}
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}
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func (table *AllowedIPs) Insert(prefix netip.Prefix, peer *Peer) {
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table.mutex.Lock()
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defer table.mutex.Unlock()
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if prefix.Addr().Is6() {
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ip := prefix.Addr().As16()
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parentIndirection{&table.IPv6, 2}.insert(ip[:], uint8(prefix.Bits()), peer)
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} else if prefix.Addr().Is4() {
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ip := prefix.Addr().As4()
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parentIndirection{&table.IPv4, 2}.insert(ip[:], uint8(prefix.Bits()), peer)
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} else {
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panic(errors.New("inserting unknown address type"))
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}
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}
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func (table *AllowedIPs) Lookup(ip []byte) *Peer {
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table.mutex.RLock()
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defer table.mutex.RUnlock()
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switch len(ip) {
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case net.IPv6len:
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return table.IPv6.lookup(ip)
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case net.IPv4len:
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return table.IPv4.lookup(ip)
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default:
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panic(errors.New("looking up unknown address type"))
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}
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}
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