Unbreak building for FreeBSD (#103)

Add support for freebsd. You have to set `tun.dev` in your config. The second pass of this would be to remove the exec calls and use ioctl(2) and route(4) instead, but we can do that in a second PR.

Co-authored-by: Wade Simmons <wade@wades.im>

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
 
       - name: Build
         run: |
-          make BUILD_NUMBER="${GITHUB_REF#refs/tags/v}" release-linux
+          make BUILD_NUMBER="${GITHUB_REF#refs/tags/v}" release-linux release-freebsd
           mkdir release
           mv build/*.tar.gz release
 
@@ -278,3 +278,13 @@ jobs:
           asset_path: ./linux-latest/nebula-linux-mips64le.tar.gz
           asset_name: nebula-linux-mips64le.tar.gz
           asset_content_type: application/gzip
+
+      - name: Upload freebsd-amd64
+        uses: actions/upload-release-asset@v1.0.1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          upload_url: ${{ steps.create_release.outputs.upload_url }}
+          asset_path: ./linux-latest/nebula-freebsd-amd64.tar.gz
+          asset_name: nebula-freebsd-amd64.tar.gz
+          asset_content_type: application/gzip

Makefile

@@ -17,6 +17,7 @@ ALL_LINUX = linux-amd64 \
 
 ALL = $(ALL_LINUX) \
 	darwin-amd64 \
+	freebsd-amd64 \
 	windows-amd64
 
 all: $(ALL:%=build/%/nebula) $(ALL:%=build/%/nebula-cert)
@@ -25,12 +26,17 @@ release: $(ALL:%=build/nebula-%.tar.gz)
 
 release-linux: $(ALL_LINUX:%=build/nebula-%.tar.gz)
 
+release-freebsd: build/nebula-freebsd-amd64.tar.gz
+
 bin-windows: build/windows-amd64/nebula.exe build/windows-amd64/nebula-cert.exe
 	mv $? .
 
 bin-darwin: build/darwin-amd64/nebula build/darwin-amd64/nebula-cert
 	mv $? .
 
+bin-freebsd: build/freebsd-amd64/nebula build/freebsd-amd64/nebula-cert
+	mv $? .
+
 bin:
 	go build -trimpath -ldflags "-X main.Build=$(BUILD_NUMBER)" -o ./nebula ${NEBULA_CMD_PATH}
 	go build -trimpath -ldflags "-X main.Build=$(BUILD_NUMBER)" -o ./nebula-cert ./cmd/nebula-cert

tun_freebsd.go

@@ -0,0 +1,77 @@
+package nebula
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var deviceNameRE = regexp.MustCompile(`^tun[0-9]+$`)
+
+type Tun struct {
+	Device       string
+	Cidr         *net.IPNet
+	MTU          int
+	UnsafeRoutes []route
+
+	io.ReadWriteCloser
+}
+
+func newTun(deviceName string, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) {
+	if len(routes) > 0 {
+		return nil, fmt.Errorf("Route MTU not supported in FreeBSD")
+	}
+	if strings.HasPrefix(deviceName, "/dev/") {
+		deviceName = strings.TrimPrefix(deviceName, "/dev/")
+	}
+	if !deviceNameRE.MatchString(deviceName) {
+		return nil, fmt.Errorf("tun.dev must match `tun[0-9]+`")
+	}
+	return &Tun{
+		Device:       deviceName,
+		Cidr:         cidr,
+		MTU:          defaultMTU,
+		UnsafeRoutes: unsafeRoutes,
+	}, nil
+}
+
+func (c *Tun) Activate() error {
+	var err error
+	c.ReadWriteCloser, err = os.OpenFile("/dev/"+c.Device, os.O_RDWR, 0)
+	if err != nil {
+		return fmt.Errorf("Activate failed: %v", err)
+	}
+
+	// TODO use syscalls instead of exec.Command
+	l.Debug("command: ifconfig", c.Device, c.Cidr.String(), c.Cidr.IP.String())
+	if err = exec.Command("/sbin/ifconfig", c.Device, c.Cidr.String(), c.Cidr.IP.String()).Run(); err != nil {
+		return fmt.Errorf("failed to run 'ifconfig': %s", err)
+	}
+	l.Debug("command: route", "-n", "add", "-net", c.Cidr.String(), "-interface", c.Device)
+	if err = exec.Command("/sbin/route", "-n", "add", "-net", c.Cidr.String(), "-interface", c.Device).Run(); err != nil {
+		return fmt.Errorf("failed to run 'route add': %s", err)
+	}
+	l.Debug("command: ifconfig", c.Device, "mtu", strconv.Itoa(c.MTU))
+	if err = exec.Command("/sbin/ifconfig", c.Device, "mtu", strconv.Itoa(c.MTU)).Run(); err != nil {
+		return fmt.Errorf("failed to run 'ifconfig': %s", err)
+	}
+	// Unsafe path routes
+	for _, r := range c.UnsafeRoutes {
+		l.Debug("command: route", "-n", "add", "-net", r.route.String(), "-interface", c.Device)
+		if err = exec.Command("/sbin/route", "-n", "add", "-net", r.route.String(), "-interface", c.Device).Run(); err != nil {
+			return fmt.Errorf("failed to run 'route add' for unsafe_route %s: %s", r.route.String(), err)
+		}
+	}
+
+	return nil
+}
+
+func (c *Tun) WriteRaw(b []byte) error {
+	_, err := c.Write(b)
+	return err
+}

udp_freebsd.go

@@ -0,0 +1,34 @@
+package nebula
+
+// FreeBSD support is primarily implemented in udp_generic, besides NewListenConfig
+
+import (
+	"fmt"
+	"net"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func NewListenConfig(multi bool) net.ListenConfig {
+	return net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			if multi {
+				var controlErr error
+				err := c.Control(func(fd uintptr) {
+					if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
+						controlErr = fmt.Errorf("SO_REUSEPORT failed: %v", err)
+						return
+					}
+				})
+				if err != nil {
+					return err
+				}
+				if controlErr != nil {
+					return controlErr
+				}
+			}
+			return nil
+		},
+	}
+}