headscale/matcher.go

143 lines
2.9 KiB
Go

package headscale
import (
"fmt"
"net/netip"
"strings"
"go4.org/netipx"
"tailscale.com/tailcfg"
)
// This is borrowed from, and updated to use IPSet
// https://github.com/tailscale/tailscale/blob/71029cea2ddf82007b80f465b256d027eab0f02d/wgengine/filter/tailcfg.go#L97-L162
// TODO(kradalby): contribute upstream and make public.
var (
zeroIP4 = netip.AddrFrom4([4]byte{})
zeroIP6 = netip.AddrFrom16([16]byte{})
)
// parseIPSet parses arg as one:
//
// - an IP address (IPv4 or IPv6)
// - the string "*" to match everything (both IPv4 & IPv6)
// - a CIDR (e.g. "192.168.0.0/16")
// - a range of two IPs, inclusive, separated by hyphen ("2eff::1-2eff::0800")
//
// bits, if non-nil, is the legacy SrcBits CIDR length to make a IP
// address (without a slash) treated as a CIDR of *bits length.
// nolint
func parseIPSet(arg string, bits *int) (*netipx.IPSet, error) {
var ipSet netipx.IPSetBuilder
if arg == "*" {
ipSet.AddPrefix(netip.PrefixFrom(zeroIP4, 0))
ipSet.AddPrefix(netip.PrefixFrom(zeroIP6, 0))
return ipSet.IPSet()
}
if strings.Contains(arg, "/") {
pfx, err := netip.ParsePrefix(arg)
if err != nil {
return nil, err
}
if pfx != pfx.Masked() {
return nil, fmt.Errorf("%v contains non-network bits set", pfx)
}
ipSet.AddPrefix(pfx)
return ipSet.IPSet()
}
if strings.Count(arg, "-") == 1 {
ip1s, ip2s, _ := strings.Cut(arg, "-")
ip1, err := netip.ParseAddr(ip1s)
if err != nil {
return nil, err
}
ip2, err := netip.ParseAddr(ip2s)
if err != nil {
return nil, err
}
r := netipx.IPRangeFrom(ip1, ip2)
if !r.IsValid() {
return nil, fmt.Errorf("invalid IP range %q", arg)
}
for _, prefix := range r.Prefixes() {
ipSet.AddPrefix(prefix)
}
return ipSet.IPSet()
}
ip, err := netip.ParseAddr(arg)
if err != nil {
return nil, fmt.Errorf("invalid IP address %q", arg)
}
bits8 := uint8(ip.BitLen())
if bits != nil {
if *bits < 0 || *bits > int(bits8) {
return nil, fmt.Errorf("invalid CIDR size %d for IP %q", *bits, arg)
}
bits8 = uint8(*bits)
}
ipSet.AddPrefix(netip.PrefixFrom(ip, int(bits8)))
return ipSet.IPSet()
}
type Match struct {
Srcs *netipx.IPSet
Dests *netipx.IPSet
}
func MatchFromFilterRule(rule tailcfg.FilterRule) Match {
srcs := new(netipx.IPSetBuilder)
dests := new(netipx.IPSetBuilder)
for _, srcIP := range rule.SrcIPs {
set, _ := parseIPSet(srcIP, nil)
srcs.AddSet(set)
}
for _, dest := range rule.DstPorts {
set, _ := parseIPSet(dest.IP, nil)
dests.AddSet(set)
}
srcsSet, _ := srcs.IPSet()
destsSet, _ := dests.IPSet()
match := Match{
Srcs: srcsSet,
Dests: destsSet,
}
return match
}
func (m *Match) SrcsContainsIPs(ips []netip.Addr) bool {
for _, ip := range ips {
if m.Srcs.Contains(ip) {
return true
}
}
return false
}
func (m *Match) DestsContainsIP(ips []netip.Addr) bool {
for _, ip := range ips {
if m.Dests.Contains(ip) {
return true
}
}
return false
}