compile client under freebsd (#1620)

Compile netbird client under freebsd and now support netstack and userspace modes.
Refactoring linux specific code to share same code with FreeBSD, move to *_unix.go files.

Not implemented yet:

Kernel mode not supported
DNS probably does not work yet
Routing also probably does not work yet
SSH support did not tested yet
Lack of test environment for freebsd (dedicated VM for github runners under FreeBSD required)
Lack of tests for freebsd specific code
info reporting need to review and also implement, for example OS reported as GENERIC instead of FreeBSD (lack of FreeBSD icon in management interface)
Lack of proper client setup under FreeBSD
Lack of FreeBSD port/package

client/internal/dns/consts_freebsd.go

@@ -0,0 +1,6 @@
+package dns
+
+const (
+	fileUncleanShutdownResolvConfLocation  = "/var/db/netbird/resolv.conf"
+	fileUncleanShutdownManagerTypeLocation = "/var/db/netbird/manager"
+)

client/internal/dns/consts_linux.go

@@ -0,0 +1,8 @@
+//go:build !android
+
+package dns
+
+const (
+	fileUncleanShutdownResolvConfLocation  = "/var/lib/netbird/resolv.conf"
+	fileUncleanShutdownManagerTypeLocation = "/var/lib/netbird/manager"
+)

client/internal/dns/dbus_linux.go → client/internal/dns/dbus_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/file_parser_linux.go → client/internal/dns/file_parser_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/file_parser_linux_test.go → client/internal/dns/file_parser_unix_test.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/file_repair_linux.go → client/internal/dns/file_repair_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/file_repair_linux_test.go → client/internal/dns/file_repair_unix_test.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/file_linux.go → client/internal/dns/file_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/file_linux_test.go → client/internal/dns/file_unix_test.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/host_linux.go → client/internal/dns/host_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 
@@ -108,24 +108,18 @@ func getOSDNSManagerType() (osManagerType, error) {
 		if strings.Contains(text, "NetworkManager") && isDbusListenerRunning(networkManagerDest, networkManagerDbusObjectNode) && isNetworkManagerSupported() {
 			return networkManager, nil
 		}
-		if strings.Contains(text, "systemd-resolved") && isDbusListenerRunning(systemdResolvedDest, systemdDbusObjectNode) {
+		if strings.Contains(text, "systemd-resolved") && isSystemdResolvedRunning() {
 			if checkStub() {
 				return systemdManager, nil
 			} else {
 				return fileManager, nil
 			}
 		}
 		if strings.Contains(text, "resolvconf") {
-			if isDbusListenerRunning(systemdResolvedDest, systemdDbusObjectNode) {
-				var value string
-				err = getSystemdDbusProperty(systemdDbusResolvConfModeProperty, &value)
-				if err == nil {
-					if value == systemdDbusResolvConfModeForeign {
-						return systemdManager, nil
-					}
-				}
-				log.Errorf("got an error while checking systemd resolv conf mode, error: %s", err)
+			if isSystemdResolveConfMode() {
+				return systemdManager, nil
 			}
+
 			return resolvConfManager, nil
 		}
 	}

client/internal/dns/network_manager_linux.go → client/internal/dns/network_manager_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/resolvconf_linux.go → client/internal/dns/resolvconf_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/server_linux.go → client/internal/dns/server_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 

client/internal/dns/systemd_freebsd.go

@@ -0,0 +1,20 @@
+package dns
+
+import (
+	"errors"
+	"fmt"
+)
+
+var errNotImplemented = errors.New("not implemented")
+
+func newSystemdDbusConfigurator(wgInterface string) (hostManager, error) {
+	return nil, fmt.Errorf("systemd dns management: %w on freebsd", errNotImplemented)
+}
+
+func isSystemdResolvedRunning() bool {
+	return false
+}
+
+func isSystemdResolveConfMode() bool {
+	return false
+}

client/internal/dns/systemd_linux.go

@@ -242,3 +242,25 @@ func getSystemdDbusProperty(property string, store any) error {
 
 	return v.Store(store)
 }
+
+func isSystemdResolvedRunning() bool {
+	return isDbusListenerRunning(systemdResolvedDest, systemdDbusObjectNode)
+}
+
+func isSystemdResolveConfMode() bool {
+	if !isDbusListenerRunning(systemdResolvedDest, systemdDbusObjectNode) {
+		return false
+	}
+
+	var value string
+	if err := getSystemdDbusProperty(systemdDbusResolvConfModeProperty, &value); err != nil {
+		log.Errorf("got an error while checking systemd resolv conf mode, error: %s", err)
+		return false
+	}
+
+	if value == systemdDbusResolvConfModeForeign {
+		return true
+	}
+
+	return false
+}

client/internal/dns/unclean_shutdown_linux.go → client/internal/dns/unclean_shutdown_unix.go

@@ -1,4 +1,4 @@
-//go:build !android
+//go:build (linux && !android) || freebsd
 
 package dns
 
@@ -14,11 +14,6 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-const (
-	fileUncleanShutdownResolvConfLocation  = "/var/lib/netbird/resolv.conf"
-	fileUncleanShutdownManagerTypeLocation = "/var/lib/netbird/manager"
-)
-
 func CheckUncleanShutdown(wgIface string) error {
 	if _, err := os.Stat(fileUncleanShutdownResolvConfLocation); err != nil {
 		if errors.Is(err, fs.ErrNotExist) {

client/internal/engine.go

@@ -546,8 +546,8 @@ func (e *Engine) updateSSH(sshConf *mgmProto.SSHConfig) error {
 	} else {
 
 		if sshConf.GetSshEnabled() {
-			if runtime.GOOS == "windows" {
-				log.Warnf("running SSH server on Windows is not supported")
+			if runtime.GOOS == "windows" || runtime.GOOS == "freebsd" {
+				log.Warnf("running SSH server on %s is not supported", runtime.GOOS)
 				return nil
 			}
 			// start SSH server if it wasn't running

client/internal/routemanager/routeflags_bsd.go

@@ -0,0 +1,18 @@
+//go:build darwin || dragonfly || netbsd || openbsd
+
+package routemanager
+
+import "syscall"
+
+// filterRoutesByFlags - return true if need to ignore such route message because it consists specific flags.
+func filterRoutesByFlags(routeMessageFlags int) bool {
+	if routeMessageFlags&syscall.RTF_UP == 0 {
+		return true
+	}
+
+	if routeMessageFlags&(syscall.RTF_REJECT|syscall.RTF_BLACKHOLE|syscall.RTF_WASCLONED) != 0 {
+		return true
+	}
+
+	return false
+}

client/internal/routemanager/routeflags_freebsd.go

@@ -0,0 +1,19 @@
+//go:build: freebsd
+package routemanager
+
+import "syscall"
+
+// filterRoutesByFlags - return true if need to ignore such route message because it consists specific flags.
+func filterRoutesByFlags(routeMessageFlags int) bool {
+	if routeMessageFlags&syscall.RTF_UP == 0 {
+		return true
+	}
+
+	// NOTE: syscall.RTF_WASCLONED deprecated in FreeBSD 8.0 (https://www.freebsd.org/releases/8.0R/relnotes-detailed/)
+	//  a concept of cloned route (a route generated by an entry with RTF_CLONING flag) is deprecated.
+	if routeMessageFlags&(syscall.RTF_REJECT|syscall.RTF_BLACKHOLE) != 0 {
+		return true
+	}
+
+	return false
+}

client/internal/routemanager/systemops.go

@@ -82,6 +82,10 @@ func GetNextHop(ip netip.Addr) (netip.Addr, *net.Interface, error) {
 
 	log.Debugf("Route for %s: interface %v nexthop %v, preferred source %v", ip, intf, gateway, preferredSrc)
 	if gateway == nil {
+		if runtime.GOOS == "freebsd" {
+			return netip.Addr{}, intf, nil
+		}
+
 		if preferredSrc == nil {
 			return netip.Addr{}, nil, ErrRouteNotFound
 		}

client/internal/routemanager/systemops_bsd.go

@@ -43,8 +43,7 @@ func getRoutesFromTable() ([]netip.Prefix, error) {
 			return nil, fmt.Errorf("unexpected RIB message type: %d", m.Type)
 		}
 
-		if m.Flags&syscall.RTF_UP == 0 ||
-			m.Flags&(syscall.RTF_REJECT|syscall.RTF_BLACKHOLE|syscall.RTF_WASCLONED) != 0 {
+		if filterRoutesByFlags(m.Flags) {
 			continue
 		}
 

client/internal/routemanager/systemops_darwin.go → client/internal/routemanager/systemops_unix.go

@@ -1,4 +1,4 @@
-//go:build darwin && !ios
+//go:build (darwin && !ios) || dragonfly || freebsd || netbsd || openbsd
 
 package routemanager
 

client/ssh/window_freebsd.go

@@ -0,0 +1,10 @@
+//go:build freebsd
+
+package ssh
+
+import (
+	"os"
+)
+
+func setWinSize(file *os.File, width, height int) {
+}

client/system/info_freebsd.go

@@ -1,15 +1,18 @@
+//go:build freebsd
+
 package system
 
 import (
 	"bytes"
 	"context"
-	"fmt"
 	"os"
 	"os/exec"
 	"runtime"
 	"strings"
 	"time"
 
+	log "github.com/sirupsen/logrus"
+
 	"github.com/netbirdio/netbird/client/system/detect_cloud"
 	"github.com/netbirdio/netbird/client/system/detect_platform"
 	"github.com/netbirdio/netbird/version"
@@ -22,8 +25,8 @@ func GetInfo(ctx context.Context) *Info {
 		out = _getInfo()
 		time.Sleep(500 * time.Millisecond)
 	}
-	osStr := strings.Replace(out, "\n", "", -1)
-	osStr = strings.Replace(osStr, "\r\n", "", -1)
+	osStr := strings.ReplaceAll(out, "\n", "")
+	osStr = strings.ReplaceAll(osStr, "\r\n", "")
 	osInfo := strings.Split(osStr, " ")
 
 	env := Environment{
@@ -50,7 +53,8 @@ func _getInfo() string {
 	cmd.Stderr = &stderr
 	err := cmd.Run()
 	if err != nil {
-		fmt.Println("getInfo:", err)
+		log.Warnf("getInfo: %s", err)
 	}
+
 	return out.String()
 }

client/ui/client_ui.go

@@ -1,4 +1,4 @@
-//go:build !(linux && 386)
+//go:build !(linux && 386) && !freebsd
 
 package main
 

iface/freebsd/errors.go

@@ -0,0 +1,8 @@
+package freebsd
+
+import "errors"
+
+var (
+	ErrDoesNotExist     = errors.New("does not exist")
+	ErrNameDoesNotMatch = errors.New("name does not match")
+)