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// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause
package filter
import (
"fmt"
"net/netip"
"strings"
"go4.org/netipx"
"tailscale.com/net/ipset"
"tailscale.com/net/netaddr"
"tailscale.com/tailcfg"
"tailscale.com/types/ipproto"
"tailscale.com/types/views"
)
var defaultProtos = []ipproto.Proto{
ipproto.TCP,
ipproto.UDP,
ipproto.ICMPv4,
ipproto.ICMPv6,
}
var defaultProtosView = views.SliceOf(defaultProtos)
// MatchesFromFilterRules converts tailcfg FilterRules into Matches.
// If an error is returned, the Matches result is still valid,
// containing the rules that were successfully converted.
func MatchesFromFilterRules(pf []tailcfg.FilterRule) ([]Match, error) {
mm := make([]Match, 0, len(pf))
var erracc error
for _, r := range pf {
if len(r.SrcBits) > 0 {
return nil, fmt.Errorf("unexpected SrcBits; control plane should not send this to this client version")
}
// Profiling determined that this function was spending a lot
// of time in runtime.growslice. As such, we attempt to
// pre-allocate some slices. Multipliers were chosen arbitrarily.
m := Match{
Srcs: make([]netip.Prefix, 0, len(r.SrcIPs)),
Dsts: make([]NetPortRange, 0, 2*len(r.DstPorts)),
Caps: make([]CapMatch, 0, 3*len(r.CapGrant)),
}
if len(r.IPProto) == 0 {
m.IPProto = defaultProtosView
} else {
filtered := make([]ipproto.Proto, 0, len(r.IPProto))
for _, n := range r.IPProto {
if n >= 0 && n <= 0xff {
filtered = append(filtered, ipproto.Proto(n))
}
}
m.IPProto = views.SliceOf(filtered)
}
for _, s := range r.SrcIPs {
nets, cap, err := parseIPSet(s)
if err != nil && erracc == nil {
erracc = err
continue
}
m.Srcs = append(m.Srcs, nets...)
if cap != "" {
m.SrcCaps = append(m.SrcCaps, cap)
}
}
m.SrcsContains = ipset.NewContainsIPFunc(views.SliceOf(m.Srcs))
for _, d := range r.DstPorts {
if d.Bits != nil {
return nil, fmt.Errorf("unexpected DstBits; control plane should not send this to this client version")
}
nets, cap, err := parseIPSet(d.IP)
if err != nil && erracc == nil {
erracc = err
continue
}
if cap != "" {
erracc = fmt.Errorf("unexpected capability %q in DstPorts", cap)
continue
}
for _, net := range nets {
m.Dsts = append(m.Dsts, NetPortRange{
Net: net,
Ports: PortRange{
First: d.Ports.First,
Last: d.Ports.Last,
},
})
}
}
for _, cm := range r.CapGrant {
for _, dstNet := range cm.Dsts {
for _, cap := range cm.Caps {
m.Caps = append(m.Caps, CapMatch{
Dst: dstNet,
Cap: cap,
})
}
for cap, val := range cm.CapMap {
m.Caps = append(m.Caps, CapMatch{
Dst: dstNet,
Cap: tailcfg.PeerCapability(cap),
Values: val,
})
}
}
}
mm = append(mm, m)
}
return mm, erracc
}
var (
zeroIP4 = netaddr.IPv4(0, 0, 0, 0)
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")
// - "cap:<peer-node-capability>" to match a peer node capability
//
// TODO(bradfitz): make this return an IPSet and plumb that all
// around, and ultimately use a new version of IPSet.ContainsFunc like
// Contains16Func that works in [16]byte address, so we we can match
// at runtime without allocating?
func parseIPSet(arg string) (prefixes []netip.Prefix, peerCap tailcfg.NodeCapability, err error) {
if arg == "*" {
// User explicitly requested wildcard.
return []netip.Prefix{
netip.PrefixFrom(zeroIP4, 0),
netip.PrefixFrom(zeroIP6, 0),
}, "", nil
}
if cap, ok := strings.CutPrefix(arg, "cap:"); ok {
return nil, tailcfg.NodeCapability(cap), nil
}
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)
}
return []netip.Prefix{pfx}, "", nil
}
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)
}
return r.Prefixes(), "", nil
}
ip, err := netip.ParseAddr(arg)
if err != nil {
return nil, "", fmt.Errorf("invalid IP address %q", arg)
}
return []netip.Prefix{netip.PrefixFrom(ip, ip.BitLen())}, "", nil
}
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