Using ssh-keygen to validate public key

hosting/forms.py

@@ -1,5 +1,8 @@
 import datetime
 import logging
+import subprocess
+import tempfile
+import os
 
 from django import forms
 from django.contrib.auth import authenticate
@@ -92,25 +95,22 @@ class UserHostingKeyForm(forms.ModelForm):
             return self.data.get('public_key')
         KEY_ERROR_MESSAGE = _("Please input a proper SSH key")
         openssh_pubkey_str = self.data.get('public_key')
-        try:
-            ssh_key = SSHKey(openssh_pubkey_str)
-            ssh_key.parse()
-        except InvalidKeyException as err:
-            logger.error(
-                "InvalidKeyException while parsing ssh key {0}".format(err))
-            raise forms.ValidationError(KEY_ERROR_MESSAGE)
-        except NotImplementedError as err:
-            logger.error(
-                "NotImplementedError while parsing ssh key {0}".format(err))
-            raise forms.ValidationError(KEY_ERROR_MESSAGE)
-        except UnicodeDecodeError as u:
-            logger.error(
-                "UnicodeDecodeError while parsing ssh key {0}".format(u))
-            raise forms.ValidationError(KEY_ERROR_MESSAGE)
-        except ValueError as v:
-            logger.error(
-                "ValueError while parsing ssh key {0}".format(v))
-            raise forms.ValidationError(KEY_ERROR_MESSAGE)
+
+        with tempfile.NamedTemporaryFile(delete=True) as tmp_public_key_file:
+            tmp_public_key_file.writelines(openssh_pubkey_str)
+            tmp_public_key_file.flush()
+            try:
+                out = subprocess.check_output(
+                    ['ssh-keygen', '-lf', tmp_public_key_file.name])
+            except subprocess.CalledProcessError as cpe:
+                logger.debug(
+                    "Not a correct ssh format {error} {out}".format(
+                        error=str(cpe), out=out))
+                raise forms.ValidationError(KEY_ERROR_MESSAGE)
+            try:
+                os.remove(tmp_public_key_file.name)
+            except OSError:
+                pass
         return openssh_pubkey_str
 
     def clean_name(self):

utils/tasks.py

@@ -1,4 +1,5 @@
 import tempfile
+import os
 
 import cdist
 from cdist.integration import configure_hosts_simple
@@ -67,6 +68,10 @@ def save_ssh_key(self, hosts, keys):
         except Exception as cdist_exception:
             logger.error(cdist_exception)
             return_value = False
+    try:
+        os.remove(tmp_manifest.name)
+    except OSError:
+        pass
     return return_value