implement SshPublicKey model, manager and tests

- implement osusers.models.SshPublicKey and osusers.models.SshPublicKeyManager
- fix broken osusers.models.tests.test_models
- add new test classes SshPublicKeyManagerTest and SshPublicKeyTest
- add migration for SshPublicKey model

gnuviechadmin/osusers/models.py

@@ -4,9 +4,11 @@ This module defines the database models of operating system users.
 """
 from __future__ import unicode_literals
 
+import base64
 from datetime import date
 import logging
 import os
+import six
 
 from django.db import models, transaction
 from django.conf import settings
@@ -477,3 +479,103 @@ class AdditionalGroup(TimeStampedModel, models.Model):
             'remove_ldap_user_from_group'
         )
         super(AdditionalGroup, self).delete(*args, **kwargs)
+
+
+class SshPublicKeyManager(models.Manager):
+    """
+    Default manager for :py:class:`SSH public key
+    <osusers.models.SshPublicKey>` instances.
+
+    """
+
+    def parse_keytext(self, keytext):
+        """
+        Parse a SSH public key in OpenSSH or :rfc:`4716` format into its
+        components algorithm, key data and comment.
+
+        :param str keytext: key text
+        :return: triple of algorithm name, key data and comment
+        :rtype: triple of str
+
+        """
+        if keytext.startswith('---- BEGIN SSH2 PUBLIC KEY ----'):
+            comment = ''
+            data = ''
+            continued = ''
+            headers = {}
+            for line in keytext.splitlines():
+                if line == '---- BEGIN SSH2 PUBLIC KEY ----':
+                    continue
+                elif ':' in line:  # a header line
+                    header_tag, header_value = [
+                        item.strip() for item in line.split(':', 1)]
+                    if header_value.endswith('\\'):
+                        continued = header_value[:-1]
+                    else:
+                        headers[header_tag.lower()] = header_value
+                elif continued:
+                    if line.endswith('\\'):
+                        continued += line[:-1]
+                        continue
+                    header_value = continued + line
+                    headers[header_tag.lower()] = header_value
+                    continued = ''
+                elif line == '---- END SSH2 PUBLIC KEY ----':
+                    break
+                elif line:  # ignore empty lines
+                    data += line
+            if 'comment' in headers:
+                comment = headers['comment']
+        else:
+            parts = keytext.split()
+            if len(parts) > 3:
+                raise ValueError("unsupported key format")
+            data = parts[1]
+            comment = len(parts) == 3 and parts[2] or ""
+        keybytes = base64.b64decode(data)
+        parts = keybytes.split(b'\x00' * 3)
+        alglength = six.byte2int(parts[1])
+        algname = parts[1][1:1+alglength]
+        return algname, data, comment
+
+    def create_ssh_public_key(self, user, keytext):
+        """
+        Create a new :py:class:`SSH public key <osusers.models.SshPublicKey>`
+        for a user from the given key text representation. The text can be
+        either in openssh format or :rfc:`4716` format.
+
+        :param user: :py:class:`operating system user <osusers.models.User>`
+        :param str keytext: key text
+        :return: public key
+        :retype: :py:class:`osusers.models.SshPublicKey`
+
+        """
+        algorithm, data, comment = self.parse_keytext(keytext)
+        return self.create(
+            user=user, algorithm=algorithm, data=data, comment=comment)
+
+
+@python_2_unicode_compatible
+class SshPublicKey(TimeStampedModel):
+    """
+    This entity class represents single SSH keys for an :py:class:`operating
+    system user <osusers.models.User>`.
+
+    """
+    user = models.ForeignKey(User, verbose_name=_('User'))
+    algorithm = models.CharField(_('Algorithm'), max_length=20)
+    data = models.TextField(_('Key bytes'),
+                            help_text=_('Base64 encoded key bytes'))
+    comment = models.TextField(_('Comment'), blank=True)
+
+    objects = SshPublicKeyManager()
+
+    class Meta:
+        verbose_name = _('SSH public key')
+        verbose_name_plural = _('SSH public keys')
+        unique_together = [('user', 'algorithm', 'data')]
+
+    def __str__(self):
+        return "{algorithm} {data} {comment}".format(
+            algorithm=self.algorithm, data=self.data, comment=self.comment
+        ).strip()