Wireguard support for Mullvad and Windscribe (#565)

- `internal/wireguard` client package with unit tests
- Implementation works with kernel space or user space if unavailable
- `WIREGUARD_PRIVATE_KEY`
- `WIREGUARD_ADDRESS`
- `WIREGUARD_PRESHARED_KEY`
- `WIREGUARD_PORT`
- `internal/netlink` package used by `internal/wireguard`

internal/provider/windscribe/connection_test.go

@@ -0,0 +1,204 @@
+package windscribe
+
+import (
+	"errors"
+	"math/rand"
+	"net"
+	"testing"
+
+	"github.com/qdm12/gluetun/internal/configuration"
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_Windscribe_GetConnection(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		servers    []models.WindscribeServer
+		selection  configuration.ServerSelection
+		connection models.Connection
+		err        error
+	}{
+		"no server available": {
+			selection: configuration.ServerSelection{
+				VPN: constants.OpenVPN,
+			},
+			err: errors.New("no server found: for VPN openvpn; protocol udp"),
+		},
+		"no filter": {
+			servers: []models.WindscribeServer{
+				{IPs: []net.IP{net.IPv4(1, 1, 1, 1)}},
+				{IPs: []net.IP{net.IPv4(2, 2, 2, 2)}},
+				{IPs: []net.IP{net.IPv4(3, 3, 3, 3)}},
+			},
+			connection: models.Connection{
+				IP:       net.IPv4(1, 1, 1, 1),
+				Port:     1194,
+				Protocol: constants.UDP,
+			},
+		},
+		"target IP": {
+			selection: configuration.ServerSelection{
+				TargetIP: net.IPv4(2, 2, 2, 2),
+			},
+			servers: []models.WindscribeServer{
+				{IPs: []net.IP{net.IPv4(1, 1, 1, 1)}},
+				{IPs: []net.IP{net.IPv4(2, 2, 2, 2)}},
+				{IPs: []net.IP{net.IPv4(3, 3, 3, 3)}},
+			},
+			connection: models.Connection{
+				IP:       net.IPv4(2, 2, 2, 2),
+				Port:     1194,
+				Protocol: constants.UDP,
+			},
+		},
+		"with filter": {
+			selection: configuration.ServerSelection{
+				Hostnames: []string{"b"},
+			},
+			servers: []models.WindscribeServer{
+				{Hostname: "a", IPs: []net.IP{net.IPv4(1, 1, 1, 1)}},
+				{Hostname: "b", IPs: []net.IP{net.IPv4(2, 2, 2, 2)}},
+				{Hostname: "a", IPs: []net.IP{net.IPv4(3, 3, 3, 3)}},
+			},
+			connection: models.Connection{
+				IP:       net.IPv4(2, 2, 2, 2),
+				Port:     1194,
+				Protocol: constants.UDP,
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			randSource := rand.NewSource(0)
+
+			m := New(testCase.servers, randSource)
+
+			connection, err := m.GetConnection(testCase.selection)
+
+			if testCase.err != nil {
+				require.Error(t, err)
+				assert.Equal(t, testCase.err.Error(), err.Error())
+			} else {
+				assert.NoError(t, err)
+			}
+
+			assert.Equal(t, testCase.connection, connection)
+		})
+	}
+}
+
+func Test_getPort(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		selection configuration.ServerSelection
+		port      uint16
+	}{
+		"default": {
+			port: 1194,
+		},
+		"OpenVPN UDP": {
+			selection: configuration.ServerSelection{
+				VPN: constants.OpenVPN,
+			},
+			port: 1194,
+		},
+		"OpenVPN TCP": {
+			selection: configuration.ServerSelection{
+				VPN: constants.OpenVPN,
+				OpenVPN: configuration.OpenVPNSelection{
+					TCP: true,
+				},
+			},
+			port: 443,
+		},
+		"OpenVPN custom port": {
+			selection: configuration.ServerSelection{
+				VPN: constants.OpenVPN,
+				OpenVPN: configuration.OpenVPNSelection{
+					CustomPort: 1234,
+				},
+			},
+			port: 1234,
+		},
+		"Wireguard": {
+			selection: configuration.ServerSelection{
+				VPN: constants.Wireguard,
+			},
+			port: 1194,
+		},
+		"Wireguard custom port": {
+			selection: configuration.ServerSelection{
+				VPN: constants.Wireguard,
+				Wireguard: configuration.WireguardSelection{
+					CustomPort: 1234,
+				},
+			},
+			port: 1234,
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			port := getPort(testCase.selection)
+
+			assert.Equal(t, testCase.port, port)
+		})
+	}
+}
+
+func Test_getProtocol(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		selection configuration.ServerSelection
+		protocol  string
+	}{
+		"default": {
+			protocol: constants.UDP,
+		},
+		"OpenVPN UDP": {
+			selection: configuration.ServerSelection{
+				VPN: constants.OpenVPN,
+			},
+			protocol: constants.UDP,
+		},
+		"OpenVPN TCP": {
+			selection: configuration.ServerSelection{
+				VPN: constants.OpenVPN,
+				OpenVPN: configuration.OpenVPNSelection{
+					TCP: true,
+				},
+			},
+			protocol: constants.TCP,
+		},
+		"Wireguard": {
+			selection: configuration.ServerSelection{
+				VPN: constants.Wireguard,
+			},
+			protocol: constants.UDP,
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			protocol := getProtocol(testCase.selection)
+
+			assert.Equal(t, testCase.protocol, protocol)
+		})
+	}
+}