ms8.1 - further improvements for single-binary operation

Embed web-based and BPF C file templates so that nethadone
can run entirely from a pre-built binary and not require
a checkout of the source code

External JS libraries will still be pulled from CDNs when accessing
the web interface, tbd whether it's worth the trouble to embed those

cmd/nethadone.go

@@ -3,12 +3,14 @@ package main
 import (
 	"flag"
 	"log"
+	"net/http"
 
 	"github.com/alecthomas/repr"
 	"github.com/atomic77/nethadone/config"
 	"github.com/atomic77/nethadone/database"
 	"github.com/atomic77/nethadone/handlers"
 	"github.com/atomic77/nethadone/policy"
+	"github.com/atomic77/nethadone/views"
 	"github.com/gofiber/fiber/v2"
 	"github.com/gofiber/fiber/v2/middleware/adaptor"
 	"github.com/gofiber/fiber/v2/middleware/logger"
@@ -32,8 +34,8 @@ func main() {
 	database.Connect()
 	handlers.Initialize()
 
-	// Pass the engine to the Views
-	engine := html.New("./views", ".tpl")
+	// Use embedded templates
+	engine := html.NewFileSystem(http.FS(views.EmbedTemplates), ".tpl")
 	app := fiber.New(fiber.Config{
 		Views: engine,
 	})

handlers/bpf.go

@@ -88,28 +88,41 @@ func Initialize() {
 }
 
 func ApplyPolicies(ipPolicies *[]models.IpPolicy) {
-	rebuildBpf("ebpf/throttle.bpf.c.tpl", "ebpf/throttle.bpf.c", ipPolicies)
-	reattachThrottler(config.Cfg.LanInterface, tc.HandleMinEgress)
+	targFile, err := os.CreateTemp("", "throttle-*.bpf.c")
+	if err != nil {
+		log.Fatal("could not create throttler file: ", err)
+	}
+	objFile, err := os.CreateTemp("", "throttle-*.o")
+	if err != nil {
+		log.Fatal("could not create throttler object file: ", err)
+	}
+
+	rebuildBpf("throttle.bpf.c.tpl", targFile, objFile, ipPolicies)
+	reattachThrottler(objFile, config.Cfg.LanInterface, tc.HandleMinEgress)
+	os.Remove(targFile.Name())
+	os.Remove(objFile.Name())
 }
 
-func rebuildBpf(tplfile string, target string, ipPolicies *[]models.IpPolicy) {
+func rebuildBpf(tplfile string, target *os.File, objFile *os.File, ipPolicies *[]models.IpPolicy) {
 	log.Println("Rebuilding with ", len(*ipPolicies), " throttle targets from policy database")
-
-	f, err := os.Create(target)
-	if err != nil {
-		log.Fatal("failed to create rendered file ", err)
-	}
-	tpl := template.Must(template.ParseFiles(tplfile))
+	tpl := template.Must(template.ParseFS(EmbedThrottlerCode, tplfile))
 	type fdata struct {
 		IpPolicies *[]models.IpPolicy
 	}
-	err = tpl.Execute(f, fdata{IpPolicies: ipPolicies})
+
+	log.Println("Temporary file ", target.Name())
+	err := tpl.Execute(target, fdata{IpPolicies: ipPolicies})
 	if err != nil {
 		log.Fatal("failed to render file ", err)
 	}
 	// FIXME There surely must be a better way of doing this dynamically
-	cmd := exec.Command("make", "build-throttler")
-	cmd.Dir = "ebpf/"
+	cmd := exec.Command(
+		"clang", "-g", "-O2",
+		// Include both armv7 and aarch64 include folders
+		"-I/usr/include/aarch64-linux-gnu", "-I/usr/arm-linux-gnueabi/include",
+		"-Wall", "-target", "bpf", "-c", target.Name(), "-o", objFile.Name(),
+	)
+	cmd.Dir = os.TempDir()
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		log.Fatal("failed to rebuild throttler eBPF, out: ", string(out), " err: ", err)
@@ -144,7 +157,7 @@ func cleanupThrottler(iface *net.Interface) {
 
 }
 
-func reattachThrottler(ifname string, direction uint32) {
+func reattachThrottler(objFile *os.File, ifname string, direction uint32) {
 
 	log.Println("(Re)attaching throttler BPF to if ", ifname, " direction ", direction)
 
@@ -157,7 +170,7 @@ func reattachThrottler(ifname string, direction uint32) {
 	cleanupThrottler(iface)
 
 	BpfCtx.ThrottleObjs = &throttleObjects{}
-	spec, err := ebpf.LoadCollectionSpec("ebpf/throttle.o")
+	spec, err := ebpf.LoadCollectionSpec(objFile.Name())
 	if err != nil {
 		log.Fatal("failed to load spec ", err)
 	}

handlers/embed.go

@@ -0,0 +1,10 @@
+package handlers
+
+import "embed"
+
+// Currently we are handling the management of the throttler
+// ebpf outside of bpf2go due to challenges figuring out how to allow
+// live recompiling
+
+//go:embed throttle.bpf.c.tpl
+var EmbedThrottlerCode embed.FS

handlers/handlers.go

@@ -17,8 +17,6 @@ import (
 	"net"
 )
 
-// var config Config
-
 func Index(c *fiber.Ctx) error {
 	// Render index
 	return c.Render("index", fiber.Map{

views/embed.go

@@ -0,0 +1,7 @@
+package views
+
+import "embed"
+
+//go:embed *.tpl
+//go:embed **/*.tpl
+var EmbedTemplates embed.FS