cmd: allow import/running ctrld as library

cmd/cli/os_windows.go

@@ -0,0 +1,95 @@
+package cli
+
+import (
+	"errors"
+	"net"
+	"os/exec"
+	"strconv"
+
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+
+	ctrldnet "github.com/Control-D-Inc/ctrld/internal/net"
+)
+
+func setDNS(iface *net.Interface, nameservers []string) error {
+	if len(nameservers) == 0 {
+		return errors.New("empty DNS nameservers")
+	}
+	primaryDNS := nameservers[0]
+	if err := setPrimaryDNS(iface, primaryDNS); err != nil {
+		return err
+	}
+	if len(nameservers) > 1 {
+		secondaryDNS := nameservers[1]
+		_ = addSecondaryDNS(iface, secondaryDNS)
+	}
+	return nil
+}
+
+// TODO(cuonglm): should we use system API?
+func resetDNS(iface *net.Interface) error {
+	if ctrldnet.SupportsIPv6ListenLocal() {
+		if output, err := netsh("interface", "ipv6", "set", "dnsserver", strconv.Itoa(iface.Index), "dhcp"); err != nil {
+			mainLog.Load().Warn().Err(err).Msgf("failed to reset ipv6 DNS: %s", string(output))
+		}
+	}
+	output, err := netsh("interface", "ipv4", "set", "dnsserver", strconv.Itoa(iface.Index), "dhcp")
+	if err != nil {
+		mainLog.Load().Error().Err(err).Msgf("failed to reset ipv4 DNS: %s", string(output))
+		return err
+	}
+	return nil
+}
+
+func setPrimaryDNS(iface *net.Interface, dns string) error {
+	ipVer := "ipv4"
+	if ctrldnet.IsIPv6(dns) {
+		ipVer = "ipv6"
+	}
+	idx := strconv.Itoa(iface.Index)
+	output, err := netsh("interface", ipVer, "set", "dnsserver", idx, "static", dns)
+	if err != nil {
+		mainLog.Load().Error().Err(err).Msgf("failed to set primary DNS: %s", string(output))
+		return err
+	}
+	if ipVer == "ipv4" && ctrldnet.SupportsIPv6ListenLocal() {
+		// Disable IPv6 DNS, so the query will be fallback to IPv4.
+		_, _ = netsh("interface", "ipv6", "set", "dnsserver", idx, "static", "::1", "primary")
+	}
+
+	return nil
+}
+
+func addSecondaryDNS(iface *net.Interface, dns string) error {
+	ipVer := "ipv4"
+	if ctrldnet.IsIPv6(dns) {
+		ipVer = "ipv6"
+	}
+	output, err := netsh("interface", ipVer, "add", "dns", strconv.Itoa(iface.Index), dns, "index=2")
+	if err != nil {
+		mainLog.Load().Warn().Err(err).Msgf("failed to add secondary DNS: %s", string(output))
+	}
+	return nil
+}
+
+func netsh(args ...string) ([]byte, error) {
+	return exec.Command("netsh", args...).Output()
+}
+
+func currentDNS(iface *net.Interface) []string {
+	luid, err := winipcfg.LUIDFromIndex(uint32(iface.Index))
+	if err != nil {
+		mainLog.Load().Error().Err(err).Msg("failed to get interface LUID")
+		return nil
+	}
+	nameservers, err := luid.DNS()
+	if err != nil {
+		mainLog.Load().Error().Err(err).Msg("failed to get interface DNS")
+		return nil
+	}
+	ns := make([]string, 0, len(nameservers))
+	for _, nameserver := range nameservers {
+		ns = append(ns, nameserver.String())
+	}
+	return ns
+}