459 lines
15 KiB
Go
459 lines
15 KiB
Go
// Copyright 2021 the Kilo authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mesh
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import (
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"errors"
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"net"
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"sort"
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"time"
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"github.com/go-kit/kit/log"
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"github.com/go-kit/kit/log/level"
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"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
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"github.com/squat/kilo/pkg/wireguard"
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)
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const (
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logicalLocationPrefix = "location:"
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nodeLocationPrefix = "node:"
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)
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// Topology represents the logical structure of the overlay network.
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type Topology struct {
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// key is the private key of the node creating the topology.
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key wgtypes.Key
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port int
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// Location is the logical location of the local host.
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location string
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segments []*segment
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peers []*Peer
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// hostname is the hostname of the local host.
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hostname string
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// leader represents whether or not the local host
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// is the segment leader.
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leader bool
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// persistentKeepalive is the interval in seconds of the emission
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// of keepalive packets by the local node to its peers.
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persistentKeepalive time.Duration
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// privateIP is the private IP address of the local node.
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privateIP *net.IPNet
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// subnet is the Pod subnet of the local node.
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subnet *net.IPNet
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// wireGuardCIDR is the allocated CIDR of the WireGuard
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// interface of the local node within the Kilo subnet.
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// If the local node is not the leader of a location, then
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// the IP is the 0th address in the subnet, i.e. the CIDR
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// is equal to the Kilo subnet.
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wireGuardCIDR *net.IPNet
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// discoveredEndpoints is the updated map of valid discovered Endpoints
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discoveredEndpoints map[string]*net.UDPAddr
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logger log.Logger
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}
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type segment struct {
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allowedIPs []net.IPNet
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endpoint *wireguard.Endpoint
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key wgtypes.Key
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persistentKeepalive time.Duration
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// Location is the logical location of this segment.
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location string
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// cidrs is a slice of subnets of all peers in the segment.
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cidrs []*net.IPNet
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// hostnames is a slice of the hostnames of the peers in the segment.
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hostnames []string
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// leader is the index of the leader of the segment.
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leader int
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// privateIPs is a slice of private IPs of all peers in the segment.
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privateIPs []net.IP
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// wireGuardIP is the allocated IP address of the WireGuard
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// interface on the leader of the segment.
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wireGuardIP net.IP
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// allowedLocationIPs are not part of the cluster and are not peers.
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// They are directly routable from nodes within the segment.
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// A classic example is a printer that ought to be routable from other locations.
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allowedLocationIPs []net.IPNet
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}
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// NewTopology creates a new Topology struct from a given set of nodes and peers.
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func NewTopology(nodes map[string]*Node, peers map[string]*Peer, granularity Granularity, hostname string, port int, key wgtypes.Key, subnet *net.IPNet, persistentKeepalive time.Duration, logger log.Logger) (*Topology, error) {
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if logger == nil {
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logger = log.NewNopLogger()
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}
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topoMap := make(map[string][]*Node)
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for _, node := range nodes {
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var location string
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switch granularity {
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case LogicalGranularity:
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location = logicalLocationPrefix + node.Location
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// Put node in a different location, if no private
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// IP was found.
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if node.InternalIP == nil {
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location = nodeLocationPrefix + node.Name
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}
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case FullGranularity:
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location = nodeLocationPrefix + node.Name
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}
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topoMap[location] = append(topoMap[location], node)
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}
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var localLocation string
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switch granularity {
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case LogicalGranularity:
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localLocation = logicalLocationPrefix + nodes[hostname].Location
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if nodes[hostname].InternalIP == nil {
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localLocation = nodeLocationPrefix + hostname
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}
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case FullGranularity:
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localLocation = nodeLocationPrefix + hostname
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}
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t := Topology{
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key: key,
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port: port,
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hostname: hostname,
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location: localLocation,
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persistentKeepalive: persistentKeepalive,
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privateIP: nodes[hostname].InternalIP,
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subnet: nodes[hostname].Subnet,
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wireGuardCIDR: subnet,
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discoveredEndpoints: make(map[string]*net.UDPAddr),
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logger: logger,
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}
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for location := range topoMap {
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// Sort the location so the result is stable.
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sort.Slice(topoMap[location], func(i, j int) bool {
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return topoMap[location][i].Name < topoMap[location][j].Name
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})
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leader := findLeader(topoMap[location])
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if location == localLocation && topoMap[location][leader].Name == hostname {
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t.leader = true
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}
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var allowedIPs []net.IPNet
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allowedLocationIPsMap := make(map[string]struct{})
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var allowedLocationIPs []net.IPNet
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var cidrs []*net.IPNet
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var hostnames []string
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var privateIPs []net.IP
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for _, node := range topoMap[location] {
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// Allowed IPs should include:
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// - the node's allocated subnet
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// - the node's WireGuard IP
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// - the node's internal IP
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// - IPs that were specified by the allowed-location-ips annotation
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if node.Subnet != nil {
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allowedIPs = append(allowedIPs, *node.Subnet)
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}
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for _, ip := range node.AllowedLocationIPs {
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if _, ok := allowedLocationIPsMap[ip.String()]; !ok {
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allowedLocationIPs = append(allowedLocationIPs, ip)
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allowedLocationIPsMap[ip.String()] = struct{}{}
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}
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}
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if node.InternalIP != nil {
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allowedIPs = append(allowedIPs, *oneAddressCIDR(node.InternalIP.IP))
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privateIPs = append(privateIPs, node.InternalIP.IP)
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}
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cidrs = append(cidrs, node.Subnet)
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hostnames = append(hostnames, node.Name)
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}
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// The sorting has no function, but makes testing easier.
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sort.Slice(allowedLocationIPs, func(i, j int) bool {
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return allowedLocationIPs[i].String() < allowedLocationIPs[j].String()
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})
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t.segments = append(t.segments, &segment{
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allowedIPs: allowedIPs,
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endpoint: topoMap[location][leader].Endpoint,
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key: topoMap[location][leader].Key,
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persistentKeepalive: topoMap[location][leader].PersistentKeepalive,
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location: location,
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cidrs: cidrs,
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hostnames: hostnames,
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leader: leader,
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privateIPs: privateIPs,
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allowedLocationIPs: allowedLocationIPs,
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})
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level.Debug(t.logger).Log("msg", "generated segment", "location", location, "allowedIPs", allowedIPs, "endpoint", topoMap[location][leader].Endpoint, "cidrs", cidrs, "hostnames", hostnames, "leader", leader, "privateIPs", privateIPs, "allowedLocationIPs", allowedLocationIPs)
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}
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// Sort the Topology segments so the result is stable.
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sort.Slice(t.segments, func(i, j int) bool {
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return t.segments[i].location < t.segments[j].location
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})
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for _, peer := range peers {
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t.peers = append(t.peers, peer)
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}
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// Sort the Topology peers so the result is stable.
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sort.Slice(t.peers, func(i, j int) bool {
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return t.peers[i].Name < t.peers[j].Name
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})
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// We need to defensively deduplicate peer allowed IPs. If two peers claim the same IP,
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// the WireGuard configuration could flap, causing the interface to churn.
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t.peers = deduplicatePeerIPs(t.peers)
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// Copy the host node DiscoveredEndpoints in the topology as a starting point.
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for key := range nodes[hostname].DiscoveredEndpoints {
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t.discoveredEndpoints[key] = nodes[hostname].DiscoveredEndpoints[key]
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}
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// Allocate IPs to the segment leaders in a stable, coordination-free manner.
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a := newAllocator(*subnet)
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for _, segment := range t.segments {
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ipNet := a.next()
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if ipNet == nil {
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return nil, errors.New("failed to allocate an IP address; ran out of IP addresses")
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}
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segment.wireGuardIP = ipNet.IP
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segment.allowedIPs = append(segment.allowedIPs, *oneAddressCIDR(ipNet.IP))
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if t.leader && segment.location == t.location {
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t.wireGuardCIDR = &net.IPNet{IP: ipNet.IP, Mask: subnet.Mask}
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}
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// Now that the topology is ordered, update the discoveredEndpoints map
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// add new ones by going through the ordered topology: segments, nodes
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for _, node := range topoMap[segment.location] {
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for key := range node.DiscoveredEndpoints {
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if _, ok := t.discoveredEndpoints[key]; !ok {
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t.discoveredEndpoints[key] = node.DiscoveredEndpoints[key]
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}
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}
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}
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// Check for intersecting IPs in allowed location IPs
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segment.allowedLocationIPs = t.filterAllowedLocationIPs(segment.allowedLocationIPs, segment.location)
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}
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level.Debug(t.logger).Log("msg", "generated topology", "location", t.location, "hostname", t.hostname, "wireGuardIP", t.wireGuardCIDR, "privateIP", t.privateIP, "subnet", t.subnet, "leader", t.leader)
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return &t, nil
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}
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func intersect(n1, n2 net.IPNet) bool {
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return n1.Contains(n2.IP) || n2.Contains(n1.IP)
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}
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func (t *Topology) filterAllowedLocationIPs(ips []net.IPNet, location string) (ret []net.IPNet) {
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CheckIPs:
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for _, ip := range ips {
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for _, s := range t.segments {
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// Check if allowed location IPs are also allowed in other locations.
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if location != s.location {
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for _, i := range s.allowedLocationIPs {
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if intersect(ip, i) {
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level.Warn(t.logger).Log("msg", "overlapping allowed location IPnets", "IP", ip.String(), "IP2", i.String(), "segment-location", s.location)
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continue CheckIPs
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}
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}
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}
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// Check if allowed location IPs intersect with the allowed IPs.
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for _, i := range s.allowedIPs {
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if intersect(ip, i) {
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level.Warn(t.logger).Log("msg", "overlapping allowed location IPnet with allowed IPnets", "IP", ip.String(), "IP2", i.String(), "segment-location", s.location)
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continue CheckIPs
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}
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}
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// Check if allowed location IPs intersect with the private IPs of the segment.
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for _, i := range s.privateIPs {
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if ip.Contains(i) {
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level.Warn(t.logger).Log("msg", "overlapping allowed location IPnet with privateIP", "IP", ip.String(), "IP2", i.String(), "segment-location", s.location)
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continue CheckIPs
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}
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}
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}
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// Check if allowed location IPs intersect with allowed IPs of peers.
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for _, p := range t.peers {
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for _, i := range p.AllowedIPs {
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if intersect(ip, i) {
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level.Warn(t.logger).Log("msg", "overlapping allowed location IPnet with peer IPnet", "IP", ip.String(), "IP2", i.String(), "peer", p.Name)
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continue CheckIPs
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}
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}
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}
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ret = append(ret, ip)
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}
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return
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}
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func (t *Topology) updateEndpoint(endpoint *wireguard.Endpoint, key wgtypes.Key, persistentKeepalive *time.Duration) *wireguard.Endpoint {
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// Do not update non-nat peers
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if persistentKeepalive == nil || *persistentKeepalive == time.Duration(0) {
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return endpoint
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}
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e, ok := t.discoveredEndpoints[key.String()]
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if ok {
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return wireguard.NewEndpointFromUDPAddr(e)
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}
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return endpoint
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}
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// Conf generates a WireGuard configuration file for a given Topology.
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func (t *Topology) Conf() *wireguard.Conf {
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c := &wireguard.Conf{
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Config: wgtypes.Config{
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PrivateKey: &t.key,
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ListenPort: &t.port,
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ReplacePeers: true,
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},
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}
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for _, s := range t.segments {
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if s.location == t.location {
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continue
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}
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peer := wireguard.Peer{
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PeerConfig: wgtypes.PeerConfig{
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AllowedIPs: append(s.allowedIPs, s.allowedLocationIPs...),
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PersistentKeepaliveInterval: &t.persistentKeepalive,
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PublicKey: s.key,
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ReplaceAllowedIPs: true,
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},
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Endpoint: t.updateEndpoint(s.endpoint, s.key, &s.persistentKeepalive),
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}
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c.Peers = append(c.Peers, peer)
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}
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for _, p := range t.peers {
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peer := wireguard.Peer{
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PeerConfig: wgtypes.PeerConfig{
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AllowedIPs: p.AllowedIPs,
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PersistentKeepaliveInterval: &t.persistentKeepalive,
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PresharedKey: p.PresharedKey,
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PublicKey: p.PublicKey,
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ReplaceAllowedIPs: true,
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},
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Endpoint: t.updateEndpoint(p.Endpoint, p.PublicKey, p.PersistentKeepaliveInterval),
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}
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c.Peers = append(c.Peers, peer)
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}
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return c
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}
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// AsPeer generates the WireGuard peer configuration for the local location of the given Topology.
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// This configuration can be used to configure this location as a peer of another WireGuard interface.
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func (t *Topology) AsPeer() *wireguard.Peer {
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for _, s := range t.segments {
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if s.location != t.location {
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continue
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}
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p := &wireguard.Peer{
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PeerConfig: wgtypes.PeerConfig{
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AllowedIPs: s.allowedIPs,
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PublicKey: s.key,
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},
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Endpoint: s.endpoint,
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}
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return p
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}
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return nil
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}
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// PeerConf generates a WireGuard configuration file for a given peer in a Topology.
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func (t *Topology) PeerConf(name string) *wireguard.Conf {
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var pka *time.Duration
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var psk *wgtypes.Key
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for i := range t.peers {
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if t.peers[i].Name == name {
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pka = t.peers[i].PersistentKeepaliveInterval
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psk = t.peers[i].PresharedKey
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break
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}
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}
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c := &wireguard.Conf{}
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for _, s := range t.segments {
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peer := wireguard.Peer{
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PeerConfig: wgtypes.PeerConfig{
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AllowedIPs: s.allowedIPs,
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PersistentKeepaliveInterval: pka,
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PresharedKey: psk,
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PublicKey: s.key,
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},
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Endpoint: s.endpoint,
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}
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c.Peers = append(c.Peers, peer)
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}
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for i := range t.peers {
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if t.peers[i].Name == name {
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continue
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}
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peer := wireguard.Peer{
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PeerConfig: wgtypes.PeerConfig{
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AllowedIPs: t.peers[i].AllowedIPs,
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PersistentKeepaliveInterval: pka,
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PublicKey: t.peers[i].PublicKey,
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},
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Endpoint: t.peers[i].Endpoint,
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}
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c.Peers = append(c.Peers, peer)
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}
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return c
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}
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// oneAddressCIDR takes an IP address and returns a CIDR
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// that contains only that address.
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func oneAddressCIDR(ip net.IP) *net.IPNet {
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return &net.IPNet{IP: ip, Mask: net.CIDRMask(len(ip)*8, len(ip)*8)}
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}
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// findLeader selects a leader for the nodes in a segment;
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// it will select the first node that says it should lead
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// or the first node in the segment if none have volunteered,
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// always preferring those with a public external IP address,
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func findLeader(nodes []*Node) int {
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var leaders, public []int
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for i := range nodes {
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if nodes[i].Leader {
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if isPublic(nodes[i].Endpoint.IP()) {
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return i
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}
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leaders = append(leaders, i)
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}
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if nodes[i].Endpoint.IP() != nil && isPublic(nodes[i].Endpoint.IP()) {
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public = append(public, i)
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}
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}
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if len(leaders) != 0 {
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return leaders[0]
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}
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if len(public) != 0 {
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return public[0]
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}
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return 0
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}
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func deduplicatePeerIPs(peers []*Peer) []*Peer {
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ps := make([]*Peer, len(peers))
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ips := make(map[string]struct{})
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for i, peer := range peers {
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p := Peer{
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Name: peer.Name,
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Peer: wireguard.Peer{
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PeerConfig: wgtypes.PeerConfig{
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PersistentKeepaliveInterval: peer.PersistentKeepaliveInterval,
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PresharedKey: peer.PresharedKey,
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PublicKey: peer.PublicKey,
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},
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Endpoint: peer.Endpoint,
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},
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}
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for _, ip := range peer.AllowedIPs {
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if _, ok := ips[ip.String()]; ok {
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continue
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}
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p.AllowedIPs = append(p.AllowedIPs, ip)
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ips[ip.String()] = struct{}{}
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}
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ps[i] = &p
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}
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return ps
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}
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