nebula/remote_list.go

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package nebula
import (
"bytes"
"net"
"sort"
"sync"
"github.com/slackhq/nebula/iputil"
"github.com/slackhq/nebula/udp"
)
// forEachFunc is used to benefit folks that want to do work inside the lock
type forEachFunc func(addr *udp.Addr, preferred bool)
// The checkFuncs here are to simplify bulk importing LH query response logic into a single function (reset slice and iterate)
type checkFuncV4 func(vpnIp iputil.VpnIp, to *Ip4AndPort) bool
type checkFuncV6 func(vpnIp iputil.VpnIp, to *Ip6AndPort) bool
// CacheMap is a struct that better represents the lighthouse cache for humans
// The string key is the owners vpnIp
type CacheMap map[string]*Cache
// Cache is the other part of CacheMap to better represent the lighthouse cache for humans
// We don't reason about ipv4 vs ipv6 here
type Cache struct {
Learned []*udp.Addr `json:"learned,omitempty"`
Reported []*udp.Addr `json:"reported,omitempty"`
}
//TODO: Seems like we should plop static host entries in here too since the are protected by the lighthouse from deletion
// We will never clean learned/reported information for them as it stands today
// cache is an internal struct that splits v4 and v6 addresses inside the cache map
type cache struct {
v4 *cacheV4
v6 *cacheV6
}
// cacheV4 stores learned and reported ipv4 records under cache
type cacheV4 struct {
learned *Ip4AndPort
reported []*Ip4AndPort
}
// cacheV4 stores learned and reported ipv6 records under cache
type cacheV6 struct {
learned *Ip6AndPort
reported []*Ip6AndPort
}
// RemoteList is a unifying concept for lighthouse servers and clients as well as hostinfos.
// It serves as a local cache of query replies, host update notifications, and locally learned addresses
type RemoteList struct {
// Every interaction with internals requires a lock!
sync.RWMutex
// A deduplicated set of addresses. Any accessor should lock beforehand.
addrs []*udp.Addr
// These are maps to store v4 and v6 addresses per lighthouse
// Map key is the vpnIp of the person that told us about this the cached entries underneath.
// For learned addresses, this is the vpnIp that sent the packet
cache map[iputil.VpnIp]*cache
// This is a list of remotes that we have tried to handshake with and have returned from the wrong vpn ip.
// They should not be tried again during a handshake
badRemotes []*udp.Addr
// A flag that the cache may have changed and addrs needs to be rebuilt
shouldRebuild bool
}
// NewRemoteList creates a new empty RemoteList
func NewRemoteList() *RemoteList {
return &RemoteList{
addrs: make([]*udp.Addr, 0),
cache: make(map[iputil.VpnIp]*cache),
}
}
// Len locks and reports the size of the deduplicated address list
// The deduplication work may need to occur here, so you must pass preferredRanges
func (r *RemoteList) Len(preferredRanges []*net.IPNet) int {
r.Rebuild(preferredRanges)
r.RLock()
defer r.RUnlock()
return len(r.addrs)
}
// ForEach locks and will call the forEachFunc for every deduplicated address in the list
// The deduplication work may need to occur here, so you must pass preferredRanges
func (r *RemoteList) ForEach(preferredRanges []*net.IPNet, forEach forEachFunc) {
r.Rebuild(preferredRanges)
r.RLock()
for _, v := range r.addrs {
forEach(v, isPreferred(v.IP, preferredRanges))
}
r.RUnlock()
}
// CopyAddrs locks and makes a deep copy of the deduplicated address list
// The deduplication work may need to occur here, so you must pass preferredRanges
func (r *RemoteList) CopyAddrs(preferredRanges []*net.IPNet) []*udp.Addr {
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if r == nil {
return nil
}
r.Rebuild(preferredRanges)
r.RLock()
defer r.RUnlock()
c := make([]*udp.Addr, len(r.addrs))
for i, v := range r.addrs {
c[i] = v.Copy()
}
return c
}
// LearnRemote locks and sets the learned slot for the owner vpn ip to the provided addr
// Currently this is only needed when HostInfo.SetRemote is called as that should cover both handshaking and roaming.
// It will mark the deduplicated address list as dirty, so do not call it unless new information is available
//TODO: this needs to support the allow list list
func (r *RemoteList) LearnRemote(ownerVpnIp iputil.VpnIp, addr *udp.Addr) {
r.Lock()
defer r.Unlock()
if v4 := addr.IP.To4(); v4 != nil {
r.unlockedSetLearnedV4(ownerVpnIp, NewIp4AndPort(v4, uint32(addr.Port)))
} else {
r.unlockedSetLearnedV6(ownerVpnIp, NewIp6AndPort(addr.IP, uint32(addr.Port)))
}
}
// CopyCache locks and creates a more human friendly form of the internal address cache.
// This may contain duplicates and blocked addresses
func (r *RemoteList) CopyCache() *CacheMap {
r.RLock()
defer r.RUnlock()
cm := make(CacheMap)
getOrMake := func(vpnIp string) *Cache {
c := cm[vpnIp]
if c == nil {
c = &Cache{
Learned: make([]*udp.Addr, 0),
Reported: make([]*udp.Addr, 0),
}
cm[vpnIp] = c
}
return c
}
for owner, mc := range r.cache {
c := getOrMake(owner.String())
if mc.v4 != nil {
if mc.v4.learned != nil {
c.Learned = append(c.Learned, NewUDPAddrFromLH4(mc.v4.learned))
}
for _, a := range mc.v4.reported {
c.Reported = append(c.Reported, NewUDPAddrFromLH4(a))
}
}
if mc.v6 != nil {
if mc.v6.learned != nil {
c.Learned = append(c.Learned, NewUDPAddrFromLH6(mc.v6.learned))
}
for _, a := range mc.v6.reported {
c.Reported = append(c.Reported, NewUDPAddrFromLH6(a))
}
}
}
return &cm
}
// BlockRemote locks and records the address as bad, it will be excluded from the deduplicated address list
func (r *RemoteList) BlockRemote(bad *udp.Addr) {
r.Lock()
defer r.Unlock()
// Check if we already blocked this addr
if r.unlockedIsBad(bad) {
return
}
// We copy here because we are taking something else's memory and we can't trust everything
r.badRemotes = append(r.badRemotes, bad.Copy())
// Mark the next interaction must recollect/dedupe
r.shouldRebuild = true
}
// CopyBlockedRemotes locks and makes a deep copy of the blocked remotes list
func (r *RemoteList) CopyBlockedRemotes() []*udp.Addr {
r.RLock()
defer r.RUnlock()
c := make([]*udp.Addr, len(r.badRemotes))
for i, v := range r.badRemotes {
c[i] = v.Copy()
}
return c
}
// ResetBlockedRemotes locks and clears the blocked remotes list
func (r *RemoteList) ResetBlockedRemotes() {
r.Lock()
r.badRemotes = nil
r.Unlock()
}
// Rebuild locks and generates the deduplicated address list only if there is work to be done
// There is generally no reason to call this directly but it is safe to do so
func (r *RemoteList) Rebuild(preferredRanges []*net.IPNet) {
r.Lock()
defer r.Unlock()
// Only rebuild if the cache changed
//TODO: shouldRebuild is probably pointless as we don't check for actual change when lighthouse updates come in
if r.shouldRebuild {
r.unlockedCollect()
r.shouldRebuild = false
}
// Always re-sort, preferredRanges can change via HUP
r.unlockedSort(preferredRanges)
}
// unlockedIsBad assumes you have the write lock and checks if the remote matches any entry in the blocked address list
func (r *RemoteList) unlockedIsBad(remote *udp.Addr) bool {
for _, v := range r.badRemotes {
if v.Equals(remote) {
return true
}
}
return false
}
// unlockedSetLearnedV4 assumes you have the write lock and sets the current learned address for this owner and marks the
// deduplicated address list as dirty
func (r *RemoteList) unlockedSetLearnedV4(ownerVpnIp iputil.VpnIp, to *Ip4AndPort) {
r.shouldRebuild = true
r.unlockedGetOrMakeV4(ownerVpnIp).learned = to
}
// unlockedSetV4 assumes you have the write lock and resets the reported list of ips for this owner to the list provided
// and marks the deduplicated address list as dirty
func (r *RemoteList) unlockedSetV4(ownerVpnIp iputil.VpnIp, vpnIp iputil.VpnIp, to []*Ip4AndPort, check checkFuncV4) {
r.shouldRebuild = true
c := r.unlockedGetOrMakeV4(ownerVpnIp)
// Reset the slice
c.reported = c.reported[:0]
// We can't take their array but we can take their pointers
for _, v := range to[:minInt(len(to), MaxRemotes)] {
if check(vpnIp, v) {
c.reported = append(c.reported, v)
}
}
}
// unlockedPrependV4 assumes you have the write lock and prepends the address in the reported list for this owner
// This is only useful for establishing static hosts
func (r *RemoteList) unlockedPrependV4(ownerVpnIp iputil.VpnIp, to *Ip4AndPort) {
r.shouldRebuild = true
c := r.unlockedGetOrMakeV4(ownerVpnIp)
// We are doing the easy append because this is rarely called
c.reported = append([]*Ip4AndPort{to}, c.reported...)
if len(c.reported) > MaxRemotes {
c.reported = c.reported[:MaxRemotes]
}
}
// unlockedSetLearnedV6 assumes you have the write lock and sets the current learned address for this owner and marks the
// deduplicated address list as dirty
func (r *RemoteList) unlockedSetLearnedV6(ownerVpnIp iputil.VpnIp, to *Ip6AndPort) {
r.shouldRebuild = true
r.unlockedGetOrMakeV6(ownerVpnIp).learned = to
}
// unlockedSetV6 assumes you have the write lock and resets the reported list of ips for this owner to the list provided
// and marks the deduplicated address list as dirty
func (r *RemoteList) unlockedSetV6(ownerVpnIp iputil.VpnIp, vpnIp iputil.VpnIp, to []*Ip6AndPort, check checkFuncV6) {
r.shouldRebuild = true
c := r.unlockedGetOrMakeV6(ownerVpnIp)
// Reset the slice
c.reported = c.reported[:0]
// We can't take their array but we can take their pointers
for _, v := range to[:minInt(len(to), MaxRemotes)] {
if check(vpnIp, v) {
c.reported = append(c.reported, v)
}
}
}
// unlockedPrependV6 assumes you have the write lock and prepends the address in the reported list for this owner
// This is only useful for establishing static hosts
func (r *RemoteList) unlockedPrependV6(ownerVpnIp iputil.VpnIp, to *Ip6AndPort) {
r.shouldRebuild = true
c := r.unlockedGetOrMakeV6(ownerVpnIp)
// We are doing the easy append because this is rarely called
c.reported = append([]*Ip6AndPort{to}, c.reported...)
if len(c.reported) > MaxRemotes {
c.reported = c.reported[:MaxRemotes]
}
}
// unlockedGetOrMakeV4 assumes you have the write lock and builds the cache and owner entry. Only the v4 pointer is established.
// The caller must dirty the learned address cache if required
func (r *RemoteList) unlockedGetOrMakeV4(ownerVpnIp iputil.VpnIp) *cacheV4 {
am := r.cache[ownerVpnIp]
if am == nil {
am = &cache{}
r.cache[ownerVpnIp] = am
}
// Avoid occupying memory for v6 addresses if we never have any
if am.v4 == nil {
am.v4 = &cacheV4{}
}
return am.v4
}
// unlockedGetOrMakeV6 assumes you have the write lock and builds the cache and owner entry. Only the v6 pointer is established.
// The caller must dirty the learned address cache if required
func (r *RemoteList) unlockedGetOrMakeV6(ownerVpnIp iputil.VpnIp) *cacheV6 {
am := r.cache[ownerVpnIp]
if am == nil {
am = &cache{}
r.cache[ownerVpnIp] = am
}
// Avoid occupying memory for v4 addresses if we never have any
if am.v6 == nil {
am.v6 = &cacheV6{}
}
return am.v6
}
// unlockedCollect assumes you have the write lock and collects/transforms the cache into the deduped address list.
// The result of this function can contain duplicates. unlockedSort handles cleaning it.
func (r *RemoteList) unlockedCollect() {
addrs := r.addrs[:0]
for _, c := range r.cache {
if c.v4 != nil {
if c.v4.learned != nil {
u := NewUDPAddrFromLH4(c.v4.learned)
if !r.unlockedIsBad(u) {
addrs = append(addrs, u)
}
}
for _, v := range c.v4.reported {
u := NewUDPAddrFromLH4(v)
if !r.unlockedIsBad(u) {
addrs = append(addrs, u)
}
}
}
if c.v6 != nil {
if c.v6.learned != nil {
u := NewUDPAddrFromLH6(c.v6.learned)
if !r.unlockedIsBad(u) {
addrs = append(addrs, u)
}
}
for _, v := range c.v6.reported {
u := NewUDPAddrFromLH6(v)
if !r.unlockedIsBad(u) {
addrs = append(addrs, u)
}
}
}
}
r.addrs = addrs
}
// unlockedSort assumes you have the write lock and performs the deduping and sorting of the address list
func (r *RemoteList) unlockedSort(preferredRanges []*net.IPNet) {
n := len(r.addrs)
if n < 2 {
return
}
lessFunc := func(i, j int) bool {
a := r.addrs[i]
b := r.addrs[j]
// Preferred addresses first
aPref := isPreferred(a.IP, preferredRanges)
bPref := isPreferred(b.IP, preferredRanges)
switch {
case aPref && !bPref:
// If i is preferred and j is not, i is less than j
return true
case !aPref && bPref:
// If j is preferred then i is not due to the else, i is not less than j
return false
default:
// Both i an j are either preferred or not, sort within that
}
// ipv6 addresses 2nd
a4 := a.IP.To4()
b4 := b.IP.To4()
switch {
case a4 == nil && b4 != nil:
// If i is v6 and j is v4, i is less than j
return true
case a4 != nil && b4 == nil:
// If j is v6 and i is v4, i is not less than j
return false
case a4 != nil && b4 != nil:
// Special case for ipv4, a4 and b4 are not nil
aPrivate := isPrivateIP(a4)
bPrivate := isPrivateIP(b4)
switch {
case !aPrivate && bPrivate:
// If i is a public ip (not private) and j is a private ip, i is less then j
return true
case aPrivate && !bPrivate:
// If j is public (not private) then i is private due to the else, i is not less than j
return false
default:
// Both i an j are either public or private, sort within that
}
default:
// Both i an j are either ipv4 or ipv6, sort within that
}
// lexical order of ips 3rd
c := bytes.Compare(a.IP, b.IP)
if c == 0 {
// Ips are the same, Lexical order of ports 4th
return a.Port < b.Port
}
// Ip wasn't the same
return c < 0
}
// Sort it
sort.Slice(r.addrs, lessFunc)
// Deduplicate
a, b := 0, 1
for b < n {
if !r.addrs[a].Equals(r.addrs[b]) {
a++
if a != b {
r.addrs[a], r.addrs[b] = r.addrs[b], r.addrs[a]
}
}
b++
}
r.addrs = r.addrs[:a+1]
return
}
// minInt returns the minimum integer of a or b
func minInt(a, b int) int {
if a < b {
return a
}
return b
}
// isPreferred returns true of the ip is contained in the preferredRanges list
func isPreferred(ip net.IP, preferredRanges []*net.IPNet) bool {
//TODO: this would be better in a CIDR6Tree
for _, p := range preferredRanges {
if p.Contains(ip) {
return true
}
}
return false
}
var _, private24BitBlock, _ = net.ParseCIDR("10.0.0.0/8")
var _, private20BitBlock, _ = net.ParseCIDR("172.16.0.0/12")
var _, private16BitBlock, _ = net.ParseCIDR("192.168.0.0/16")
// isPrivateIP returns true if the ip is contained by a rfc 1918 private range
func isPrivateIP(ip net.IP) bool {
//TODO: another great cidrtree option
//TODO: Private for ipv6 or just let it ride?
return private24BitBlock.Contains(ip) || private20BitBlock.Contains(ip) || private16BitBlock.Contains(ip)
}