move all go files from root to hscontrol

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/matcher.go

@@ -0,0 +1,142 @@
+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
+}