// 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" "strings" "inet.af/netaddr" "tailscale.com/tailcfg" "tailscale.com/types/ipproto" ) var defaultProtos = []ipproto.Proto{ ipproto.TCP, ipproto.UDP, ipproto.ICMPv4, ipproto.ICMPv6, } // 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{} if len(r.IPProto) == 0 { m.IPProto = append([]ipproto.Proto(nil), defaultProtos...) } else { m.IPProto = make([]ipproto.Proto, 0, len(r.IPProto)) for _, n := range r.IPProto { if n >= 0 && n <= 0xff { m.IPProto = append(m.IPProto, ipproto.Proto(n)) } } } for i, s := range r.SrcIPs { var bits *int if len(r.SrcBits) > i { bits = &r.SrcBits[i] } nets, err := parseIPSet(s, bits) if err != nil && erracc == nil { erracc = err continue } m.Srcs = append(m.Srcs, nets...) } for _, d := range r.DstPorts { nets, err := parseIPSet(d.IP, d.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{}) ) // 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. // // 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, bits *int) ([]netaddr.IPPrefix, error) { if arg == "*" { // User explicitly requested wildcard. return []netaddr.IPPrefix{ {IP: zeroIP4, Bits: 0}, {IP: zeroIP6, Bits: 0}, }, nil } if strings.Contains(arg, "/") { pfx, err := netaddr.ParseIPPrefix(arg) if err != nil { return nil, err } if pfx != pfx.Masked() { return nil, fmt.Errorf("%v contains non-network bits set", pfx) } return []netaddr.IPPrefix{pfx}, nil } if strings.Count(arg, "-") == 1 { i := strings.Index(arg, "-") ip1s, ip2s := arg[:i], arg[i+1:] ip1, err := netaddr.ParseIP(ip1s) if err != nil { return nil, err } ip2, err := netaddr.ParseIP(ip2s) if err != nil { return nil, err } r := netaddr.IPRange{From: ip1, To: ip2} if !r.Valid() { return nil, fmt.Errorf("invalid IP range %q", arg) } return r.Prefixes(), nil } ip, err := netaddr.ParseIP(arg) if err != nil { return nil, fmt.Errorf("invalid IP address %q", arg) } bits8 := 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) } return []netaddr.IPPrefix{{IP: ip, Bits: bits8}}, nil }