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tailscale/wgengine/filter/tailcfg.go

100 lines
2.3 KiB
Go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package filter
import (
"fmt"
"inet.af/netaddr"
"tailscale.com/tailcfg"
)
// 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 {
m := Match{}
for i, s := range r.SrcIPs {
bits := 32
if len(r.SrcBits) > i {
bits = r.SrcBits[i]
}
nets, err := parseIP(s, bits)
if err != nil && erracc == nil {
erracc = err
continue
}
m.Srcs = append(m.Srcs, nets...)
}
for _, d := range r.DstPorts {
bits := 32
if d.Bits != nil {
bits = *d.Bits
}
nets, err := parseIP(d.IP, bits)
if err != nil && erracc == nil {
erracc = err
continue
}
for _, net := range nets {
m.Dsts = append(m.Dsts, NetPortRange{
Net: net,
Ports: PortRange{
First: d.Ports.First,
Last: d.Ports.Last,
},
})
}
}
mm = append(mm, m)
}
return mm, erracc
}
var (
zeroIP4 = netaddr.IPv4(0, 0, 0, 0)
zeroIP6 = netaddr.IPFrom16([16]byte{})
)
func parseIP(host string, defaultBits int) ([]netaddr.IPPrefix, error) {
if host == "*" {
// User explicitly requested wildcard dst ip.
return []netaddr.IPPrefix{
{IP: zeroIP4, Bits: 0},
{IP: zeroIP6, Bits: 0},
}, nil
}
ip, err := netaddr.ParseIP(host)
if err != nil {
return nil, fmt.Errorf("ports=%#v: invalid IP address", host)
}
if ip == zeroIP4 {
// For clarity, reject 0.0.0.0 as an input
return nil, fmt.Errorf("ports=%#v: to allow all IP addresses, use *:port, not 0.0.0.0:port", host)
}
if ip == zeroIP6 {
// For clarity, reject :: as an input
return nil, fmt.Errorf("ports=%#v: to allow all IP addresses, use *:port, not [::]:port", host)
}
if defaultBits < 0 || (ip.Is4() && defaultBits > 32) || (ip.Is6() && defaultBits > 128) {
return nil, fmt.Errorf("invalid CIDR size %d for host %q", defaultBits, host)
}
return []netaddr.IPPrefix{
{
IP: ip,
Bits: uint8(defaultBits),
},
}, nil
}