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tailscale/net/tstun/table/table.go

91 lines
2.4 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package table provides a Routing Table implementation which allows
// looking up the peer that should be used to route a given IP address.
package table
import (
"net/netip"
"tailscale.com/tempfork/device"
"tailscale.com/types/key"
"tailscale.com/util/mak"
)
// RoutingTableBuilder is a builder for a RoutingTable.
// It is not safe for concurrent use.
type RoutingTableBuilder struct {
// peers is a map from node public key to the peer that owns that key.
// It is only used to handle insertions and deletions.
peers map[key.NodePublic]*device.Peer
// prefixTrie is a trie of prefixes which facilitates looking up the
// peer that owns a given IP address.
prefixTrie *device.AllowedIPs
}
// Remove removes the given peer from the routing table.
func (t *RoutingTableBuilder) Remove(peer key.NodePublic) {
p, ok := t.peers[peer]
if !ok {
return
}
t.prefixTrie.RemoveByPeer(p)
delete(t.peers, peer)
}
// InsertOrReplace inserts the given peer and prefixes into the routing table.
func (t *RoutingTableBuilder) InsertOrReplace(peer key.NodePublic, pfxs ...netip.Prefix) {
p, ok := t.peers[peer]
if !ok {
p = device.NewPeer(peer)
mak.Set(&t.peers, peer, p)
} else {
t.prefixTrie.RemoveByPeer(p)
}
if len(pfxs) == 0 {
return
}
if t.prefixTrie == nil {
t.prefixTrie = new(device.AllowedIPs)
}
for _, pfx := range pfxs {
t.prefixTrie.Insert(pfx, p)
}
}
// Build returns a RoutingTable that can be used to look up peers.
// Build resets the RoutingTableBuilder to its zero value.
func (t *RoutingTableBuilder) Build() *RoutingTable {
pt := t.prefixTrie
t.prefixTrie = nil
t.peers = nil
return &RoutingTable{
prefixTrie: pt,
}
}
// RoutingTable provides a mapping from IP addresses to peers identified by
// their public node key. It is used to find the peer that should be used to
// route a given IP address.
// It is immutable after creation.
//
// It is safe for concurrent use.
type RoutingTable struct {
prefixTrie *device.AllowedIPs
}
// Lookup returns the peer that would be used to route the given IP address.
// If no peer is found, Lookup returns the zero value.
func (t *RoutingTable) Lookup(ip netip.Addr) (_ key.NodePublic, ok bool) {
if t == nil {
return key.NodePublic{}, false
}
p := t.prefixTrie.Lookup(ip.AsSlice())
if p == nil {
return key.NodePublic{}, false
}
return p.Key(), true
}