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Check 'hosts' file records, during handling DNS requests
This implementation use 'libhosty' lib to read and search for hosts file records. It reads 'hosts' file first and adds file watcher to track changes in 'hosts' file Signed-off-by: Yevhen Vydolob <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,94 @@ | ||
| package dns | ||
|
|
||
| import ( | ||
| "net" | ||
| "sync" | ||
|
|
||
| "github.com/areYouLazy/libhosty" | ||
| "github.com/fsnotify/fsnotify" | ||
| log "github.com/sirupsen/logrus" | ||
| ) | ||
|
|
||
| type HostsFile interface { | ||
| LookupByHostname(name string) (net.IP, error) | ||
| } | ||
|
|
||
| type hosts struct { | ||
| hostsReadLock sync.RWMutex | ||
| hostsFilePath string | ||
| hostsFile *libhosty.HostsFile | ||
| } | ||
|
|
||
| // NewHostsFile Creates new HostsFile instance | ||
| // Pass ""(empty string) if you want to use default hosts file | ||
| func NewHostsFile(hostsPath string) (HostsFile, error) { | ||
| hostsFile, err := readHostsFile(hostsPath) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| watcher, err := fsnotify.NewWatcher() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| h := &hosts{ | ||
| hostsFile: hostsFile, | ||
| hostsFilePath: hostsFile.Config.FilePath, | ||
| } | ||
| go func() { | ||
| h.startWatch(watcher) | ||
| }() | ||
| return h, nil | ||
| } | ||
|
|
||
| func (h *hosts) startWatch(w *fsnotify.Watcher) { | ||
| err := w.Add(h.hostsFilePath) | ||
| if err != nil { | ||
| log.Errorf("Hosts file adding watcher error:%s", err) | ||
| return | ||
| } | ||
| for { | ||
| select { | ||
| case err, ok := <-w.Errors: | ||
| if !ok { | ||
| return | ||
| } | ||
| log.Errorf("Hosts file watcher error:%s", err) | ||
| case event, ok := <-w.Events: | ||
| if !ok { | ||
| return | ||
| } | ||
| if event.Op&fsnotify.Write == fsnotify.Write { | ||
| err := h.updateHostsFile() | ||
| if err != nil { | ||
| log.Errorf("Hosts file read error:%s", err) | ||
| return | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func (h *hosts) LookupByHostname(name string) (net.IP, error) { | ||
| _, ip, err := h.hostsFile.LookupByHostname(name) | ||
| return ip, err | ||
| } | ||
|
|
||
| func (h *hosts) updateHostsFile() error { | ||
| h.hostsReadLock.RLock() | ||
| defer h.hostsReadLock.RUnlock() | ||
| newHosts, err := readHostsFile(h.hostsFilePath) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| h.hostsFile = newHosts | ||
| return nil | ||
| } | ||
|
|
||
| func readHostsFile(hostsFilePath string) (*libhosty.HostsFile, error) { | ||
| config, err := libhosty.NewHostsFileConfig(hostsFilePath) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return libhosty.InitWithConfig(config) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| package dns | ||
|
|
||
| import ( | ||
| "os" | ||
| "path/filepath" | ||
| "testing" | ||
| "time" | ||
|
|
||
| "github.com/stretchr/testify/assert" | ||
| ) | ||
|
|
||
| func TestHostsFile(t *testing.T) { | ||
| hostsFile := filepath.Join(t.TempDir(), "hosts") | ||
| assert.NoError(t, os.WriteFile(hostsFile, []byte(`127.0.0.1 entry1`), 0600)) | ||
|
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| hosts, err := NewHostsFile(hostsFile) | ||
| assert.NoError(t, err) | ||
| ip, err := hosts.LookupByHostname("entry1") | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, "127.0.0.1", ip.String()) | ||
| } | ||
|
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| func TestReloadingHostsFile(t *testing.T) { | ||
| hostsFile := filepath.Join(t.TempDir(), "hosts") | ||
| assert.NoError(t, os.WriteFile(hostsFile, []byte(`127.0.0.1 entry1`), 0600)) | ||
|
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||
| hosts, err := NewHostsFile(hostsFile) | ||
| time.Sleep(time.Second) | ||
| assert.NoError(t, err) | ||
| ip, err := hosts.LookupByHostname("entry1") | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, "127.0.0.1", ip.String()) | ||
|
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| assert.NoError(t, os.WriteFile(hostsFile, []byte(`127.0.0.1 entry2 foobar`), 0600)) | ||
| time.Sleep(time.Second) | ||
|
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| ipBar, err := hosts.LookupByHostname("foobar") | ||
| assert.NoError(t, err) | ||
| assert.Equal(t, "127.0.0.1", ipBar.String()) | ||
|
|
||
| } |
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