sysctl: config struct/functions for updates

Signed-off-by: John Sahhar <[email protected]>

sysctl/sysctl.go

@@ -0,0 +1,100 @@
+// package for logicing client and server code
+package sysctl
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"os"
+	"path"
+	"runtime"
+	"strings"
+)
+
+type (
+	sysctl struct {
+		path   string
+		config map[string]string
+	}
+)
+
+const (
+	NM_SYSCTL_CONF = "99-nm.conf"
+)
+
+var (
+	sysctlPaths map[string]string = map[string]string{
+		"linux":   "/usr/local/lib/sysctl.d",
+		"darwin":  "/usr/local/lib/sysctl.d",
+		"freebsd": "/usr/local/lib/sysctl.d",
+		"windows": "",
+	}
+)
+
+// Opens a file or creates it if non-existent, caller is responsible for closing the file.
+func openOrCreate(path string) (f *os.File, err error) {
+	f, err = os.OpenFile(path, os.O_RDWR, 066)
+	if err != nil {
+		f, err = os.Create(path)
+	}
+	return
+}
+
+func (s *sysctl) set(key, value string) {
+	s.config[key] = value
+}
+
+func (s *sysctl) get(key string) (val string) {
+	val, _ = s.config[key]
+	return
+}
+
+func (s *sysctl) delete(key string) {
+	delete(s.config, key)
+}
+
+func (s *sysctl) update() error {
+	f, err := openOrCreate(s.path)
+	if err != nil || f == nil {
+		return err
+	}
+	defer f.Close()
+	for k, v := range s.config {
+		ln := []byte(fmt.Sprintf("%s\n", strings.Join([]string{k, v}, "=")))
+		if _, err := f.Write(ln); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func load() (s *sysctl, err error) {
+	s = &sysctl{
+		path:   path.Join(sysctlPaths[runtime.GOOS], NM_SYSCTL_CONF),
+		config: make(map[string]string),
+	}
+	f, err := openOrCreate(s.path)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	for sc := bufio.NewScanner(f); sc.Scan(); {
+		line := sc.Bytes()
+		if len(line) >= 1 && line[0] == '#' {
+			continue
+		}
+		if kvpair := bytes.Split(line, []byte{'='}); len(kvpair) == 2 {
+			s.config[string(kvpair[0])] = string(kvpair[1])
+		}
+	}
+	return
+}
+
+func SysctlSetIPForwarding() error {
+	conf, err := load()
+	if err != nil {
+		return err
+	}
+	conf.set("net.ipv4.ip_forward", "1")
+	return conf.update()
+}

sysctl/sysctl_test.go

@@ -0,0 +1,23 @@
+// package for logicing client and server code
+package sysctl
+
+import (
+	"testing"
+)
+
+func Test_sysctl_load(t *testing.T) {
+	sctl, err := load()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log(sctl.config)
+	sctl.set("net.ipv4.conf.all.secure_redirects", "1")
+	if err := sctl.update(); err != nil {
+		t.Fatal(err)
+	}
+	sctl, err = load()
+	if val, ok := sctl.config["net.ipv4.conf.all.secure_redirects"]; !ok || val != "1" {
+		t.Fatalf("Expected updated value net.ipv4.conf.all.secure_redirects to equal 1, received: exists: %v, val: %s", ok, val)
+	}
+
+}