Implements PostUp and PostDown commands using /bin/sh

CONFIG.md

@@ -66,6 +66,14 @@ with [hugo](https://gohugo.io/)
 network overview page. The shortcode file is included in this repository under
 `etc/`.
 
+        "PostUp": ""
+        "PostDown": ""
+
+Allows a user to specify commands to run after the device is up or down. This is
+typcially a collection of `iptables` invocations. The commands are executed by
+`/bin/sh`. *NOTE* These commands run as root, so make sure you check that they
+are secure.
+
         "PrivateKey": "uC+xz3v1mfjWBHepwiCgAmPebZcY+EdhaHAvqX2r7U8=",
 
 The server private key, automatically generated and very sensitive!

README.md

@@ -73,6 +73,8 @@ Main (automatically generated) configuration example:
         "Networks": [],
         "ReportFile": "/var/lib/dsnetreport.json",
         "PrivateKey": "uC+xz3v1mfjWBHepwiCgAmPebZcY+EdhaHAvqX2r7U8=",
+        "PostUp": "",
+        "PostDown" "",
         "Peers": [
             {
                 "Hostname": "test",

add.go

@@ -151,7 +151,6 @@ func PrintPeerCfg(peer PeerConfig, conf *DsnetConfig) {
 		wgifSeed += int(b)
 	}
 
-
 	t := template.Must(template.New("peerConf").Parse(peerConf))
 	err := t.Execute(os.Stdout, map[string]interface{}{
 		"Peer":        peer,
@@ -162,7 +161,7 @@ func PrintPeerCfg(peer PeerConfig, conf *DsnetConfig) {
 		// vyatta requires an interface in range/format wg0-wg999
 		// deterministically choosing one in this range will probably allow use
 		// of the config without a colliding interface name
-		"Wgif":        fmt.Sprintf("wg%d", wgifSeed % 999),
+		"Wgif": fmt.Sprintf("wg%d", wgifSeed%999),
 	})
 	check(err)
 }

configtypes.go

@@ -51,9 +51,11 @@ type DsnetConfig struct {
 	// extra networks available, will be added to AllowedIPs
 	Networks []JSONIPNet `validate:"required"`
 	// TODO Default subnets to route via VPN
-	ReportFile string       `validate:"required"`
-	PrivateKey JSONKey      `validate:"required,len=44"`
-	Peers      []PeerConfig `validate:"dive"`
+	ReportFile string  `validate:"required"`
+	PrivateKey JSONKey `validate:"required,len=44"`
+	PostUp   string
+	PostDown string
+	Peers    []PeerConfig `validate:"dive"`
 }
 
 func MustLoadDsnetConfig() *DsnetConfig {

down.go

@@ -7,6 +7,11 @@ import (
 func Down() {
 	conf := MustLoadDsnetConfig()
 	DelLink(conf)
+	RunPostDown(conf)
+}
+
+func RunPostDown(conf *DsnetConfig) {
+	ShellOut(conf.PostDown, "PostDown")
 }
 
 func DelLink(conf *DsnetConfig) {

reporttypes.go

@@ -163,7 +163,7 @@ type PeerReport struct {
 	// date peer was added to dsnet config
 	Added time.Time
 	// Internal VPN IP address. Added to AllowedIPs in server config as a /32
-	IP net.IP
+	IP  net.IP
 	IP6 net.IP
 	// Last known external IP
 	ExternalIP net.IP

up.go

@@ -10,6 +10,11 @@ func Up() {
 	conf := MustLoadDsnetConfig()
 	CreateLink(conf)
 	ConfigureDevice(conf)
+	RunPostUp(conf)
+}
+
+func RunPostUp(conf *DsnetConfig) {
+	ShellOut(conf.PostUp, "PostUp")
 }
 
 func CreateLink(conf *DsnetConfig) {

util.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"os/exec"
 	"strings"
 )
 
@@ -35,6 +36,17 @@ func ExitFail(format string, a ...interface{}) {
 	os.Exit(1)
 }
 
+func ShellOut(command string, name string) {
+	if command != "" {
+        fmt.Printf("Running %s commands:\n %s", name, command)
+		shell := exec.Command("/bin/sh", "-c", command)
+		err := shell.Run()
+		if err != nil {
+			ExitFail("%s '%s' failed", name, command, err)
+		}
+	}
+}
+
 func ConfirmOrAbort(format string, a ...interface{}) {
 	fmt.Fprintf(os.Stderr, format+" [y/n] ", a...)