Proxy: Add MASQUE inbound (IETF CONNECT-IP server, RFC 9484) (#6844)

Completes https://github.com/XTLS/Xray-core/pull/6807 and https://github.com/XTLS/Xray-core/pull/6810

proxy/masque/pool_test.go

@@ -0,0 +1,59 @@
+package masque
+
+import (
+	"net/netip"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func allocateAll(p *addressPool) []netip.Addr {
+	var addrs []netip.Addr
+	for {
+		addr, ok := p.allocate()
+		if !ok {
+			return addrs
+		}
+		addrs = append(addrs, addr)
+	}
+}
+
+func TestAddressPool(t *testing.T) {
+	p, err := newAddressPool(netip.MustParsePrefix("10.0.0.1/29"))
+	require.NoError(t, err)
+	var want []netip.Addr
+	for _, s := range []string{"10.0.0.2", "10.0.0.3", "10.0.0.4", "10.0.0.5", "10.0.0.6"} {
+		want = append(want, netip.MustParseAddr(s))
+	}
+	require.Equal(t, want, allocateAll(p))
+
+	p.release(netip.MustParseAddr("10.0.0.4"))
+	addr, ok := p.allocate()
+	require.True(t, ok)
+	require.Equal(t, netip.MustParseAddr("10.0.0.4"), addr)
+	_, ok = p.allocate()
+	require.False(t, ok)
+
+	p, err = newAddressPool(netip.MustParsePrefix("fd00::1/126"))
+	require.NoError(t, err)
+	require.Equal(t, []netip.Addr{netip.MustParseAddr("fd00::2"), netip.MustParseAddr("fd00::3")}, allocateAll(p))
+
+	p, err = newAddressPool(netip.MustParsePrefix("10.0.0.2/30"))
+	require.NoError(t, err)
+	require.Equal(t, []netip.Addr{netip.MustParseAddr("10.0.0.1")}, allocateAll(p))
+}
+
+func TestAddressPoolRejects(t *testing.T) {
+	for _, s := range []string{
+		"10.0.0.0/24",
+		"10.0.0.255/24",
+		"10.0.0.1/31",
+		"10.0.0.1/32",
+		"fd00::1/127",
+		"fd00::1/128",
+		"::ffff:10.0.0.1/120",
+	} {
+		_, err := newAddressPool(netip.MustParsePrefix(s))
+		require.Error(t, err, s)
+	}
+}