Refactor pkg/networkfs

Solves #11591

Signed-off-by: bobby abbott <ttobbaybbob@gmail.com>

etchosts/etchosts.go

@@ -0,0 +1,67 @@
+package etchosts
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"regexp"
+)
+
+type Record struct {
+	Hosts string
+	IP    string
+}
+
+func (r Record) WriteTo(w io.Writer) (int64, error) {
+	n, err := fmt.Fprintf(w, "%s\t%s\n", r.IP, r.Hosts)
+	return int64(n), err
+}
+
+var defaultContent = []Record{
+	{Hosts: "localhost", IP: "127.0.0.1"},
+	{Hosts: "localhost ip6-localhost ip6-loopback", IP: "::1"},
+	{Hosts: "ip6-localnet", IP: "fe00::0"},
+	{Hosts: "ip6-mcastprefix", IP: "ff00::0"},
+	{Hosts: "ip6-allnodes", IP: "ff02::1"},
+	{Hosts: "ip6-allrouters", IP: "ff02::2"},
+}
+
+func Build(path, IP, hostname, domainname string, extraContent []Record) error {
+	content := bytes.NewBuffer(nil)
+	if IP != "" {
+		var mainRec Record
+		mainRec.IP = IP
+		if domainname != "" {
+			mainRec.Hosts = fmt.Sprintf("%s.%s %s", hostname, domainname, hostname)
+		} else {
+			mainRec.Hosts = hostname
+		}
+		if _, err := mainRec.WriteTo(content); err != nil {
+			return err
+		}
+	}
+
+	for _, r := range defaultContent {
+		if _, err := r.WriteTo(content); err != nil {
+			return err
+		}
+	}
+
+	for _, r := range extraContent {
+		if _, err := r.WriteTo(content); err != nil {
+			return err
+		}
+	}
+
+	return ioutil.WriteFile(path, content.Bytes(), 0644)
+}
+
+func Update(path, IP, hostname string) error {
+	old, err := ioutil.ReadFile(path)
+	if err != nil {
+		return err
+	}
+	var re = regexp.MustCompile(fmt.Sprintf("(\\S*)(\\t%s)", regexp.QuoteMeta(hostname)))
+	return ioutil.WriteFile(path, re.ReplaceAll(old, []byte(IP+"$2")), 0644)
+}

etchosts/etchosts_test.go

@@ -0,0 +1,134 @@
+package etchosts
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func TestBuildDefault(t *testing.T) {
+	file, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+
+	// check that /etc/hosts has consistent ordering
+	for i := 0; i <= 5; i++ {
+		err = Build(file.Name(), "", "", "", nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		content, err := ioutil.ReadFile(file.Name())
+		if err != nil {
+			t.Fatal(err)
+		}
+		expected := "127.0.0.1\tlocalhost\n::1\tlocalhost ip6-localhost ip6-loopback\nfe00::0\tip6-localnet\nff00::0\tip6-mcastprefix\nff02::1\tip6-allnodes\nff02::2\tip6-allrouters\n"
+
+		if expected != string(content) {
+			t.Fatalf("Expected to find '%s' got '%s'", expected, content)
+		}
+	}
+}
+
+func TestBuildHostnameDomainname(t *testing.T) {
+	file, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+
+	err = Build(file.Name(), "10.11.12.13", "testhostname", "testdomainname", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	content, err := ioutil.ReadFile(file.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expected := "10.11.12.13\ttesthostname.testdomainname testhostname\n"; !bytes.Contains(content, []byte(expected)) {
+		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
+	}
+}
+
+func TestBuildHostname(t *testing.T) {
+	file, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+
+	err = Build(file.Name(), "10.11.12.13", "testhostname", "", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	content, err := ioutil.ReadFile(file.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expected := "10.11.12.13\ttesthostname\n"; !bytes.Contains(content, []byte(expected)) {
+		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
+	}
+}
+
+func TestBuildNoIP(t *testing.T) {
+	file, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+
+	err = Build(file.Name(), "", "testhostname", "", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	content, err := ioutil.ReadFile(file.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expected := ""; !bytes.Contains(content, []byte(expected)) {
+		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
+	}
+}
+
+func TestUpdate(t *testing.T) {
+	file, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.Remove(file.Name())
+
+	if err := Build(file.Name(), "10.11.12.13", "testhostname", "testdomainname", nil); err != nil {
+		t.Fatal(err)
+	}
+
+	content, err := ioutil.ReadFile(file.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expected := "10.11.12.13\ttesthostname.testdomainname testhostname\n"; !bytes.Contains(content, []byte(expected)) {
+		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
+	}
+
+	if err := Update(file.Name(), "1.1.1.1", "testhostname"); err != nil {
+		t.Fatal(err)
+	}
+
+	content, err = ioutil.ReadFile(file.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if expected := "1.1.1.1\ttesthostname.testdomainname testhostname\n"; !bytes.Contains(content, []byte(expected)) {
+		t.Fatalf("Expected to find '%s' got '%s'", expected, content)
+	}
+}