sshd: fix generation of authorized_keys

No need to parse. This fixes several issues:
- key comments were messing up everything
- sometimes keys were repeated
- no way to remove key

slapos/recipe/dropbear.py

@@ -24,8 +24,7 @@
 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #
 ##############################################################################
-import os
-import itertools
+import errno, os
 from slapos.recipe.librecipe import GenericBaseRecipe
 
 class KnownHostsFile(dict):
@@ -55,40 +54,6 @@ class KnownHostsFile(dict):
   def __exit__(self, exc_type, exc_value, traceback):
     self._dump()
 
-
-
-class AuthorizedKeysFile(object):
-
-  def __init__(self, filename):
-    self.filename = filename
-
-  def append(self, key):
-    """Append the key to the file if the key's not in the file
-    """
-    # Create the file it it does not exist
-    try:
-      file_ = os.open(self.filename, os.O_CREAT | os.O_EXCL)
-      os.close(file_)
-    except:
-      pass
-
-    with open(self.filename, 'r') as keyfile:
-      # itertools.imap avoid loading all the authorized_keys file in
-      # memory which would be counterproductive.
-      present = (key.strip() in itertools.imap(lambda k: k.strip(),
-                                               keyfile))
-      try:
-        keyfile.seek(-1, os.SEEK_END)
-        ended_by_newline = (keyfile.read() == '\n')
-      except IOError:
-        ended_by_newline = True
-
-    if not present:
-      with open(self.filename, 'a') as keyfile:
-        if not ended_by_newline:
-          keyfile.write('\n')
-        keyfile.write(key.strip())
-
 class Recipe(GenericBaseRecipe):
 
   def install(self):
@@ -164,37 +129,29 @@ class Client(GenericBaseRecipe):
     return [wrapper]
 
 
-def keysplit(s):
-  """
-  Split a string like "ssh-rsa AKLFKJSL..... ssh-rsa AAAASAF...."
-  and return the individual key_type + key strings.
-
-  TODO: handle comments in ssh keys, which are generated
-        by default at key creation.
-  """
-  s = s.replace('\n', ' ')
-  si = iter(s.split(' '))
-  while True:
-    key_type = next(si)
-    if key_type == '':
-      continue
-    try:
-      key_value = next(si)
-    except StopIteration:
-      # odd number of elements, should not happen
-      break
-    yield '%s %s' % (key_type, key_value)
-
-
 class AddAuthorizedKey(GenericBaseRecipe):
 
   def install(self):
+    key = self.options['key']
     ssh = self.createDirectory(self.options['home'], '.ssh')
-
-    authorized_keys = AuthorizedKeysFile(os.path.join(ssh, 'authorized_keys'))
-    for key in keysplit(self.options['key']):
-      # XXX key might actually be the string 'None' or 'null'
-      authorized_keys.append(key)
-
-    return [authorized_keys.filename]
-
+    filename = os.path.join(ssh, 'authorized_keys')
+    try:
+        with open(filename) as f:
+            if f.read() == key:
+                return [filename]
+    except IOError as e:
+        if e.errno != errno.ENOENT:
+            raise
+    # Atomic update.
+    tmp = filename + '.new'
+    try:
+        with open(tmp, 'w') as f:
+            f.write(key)
+        os.rename(tmp, filename)
+    finally:
+        try:
+            os.remove(tmp)
+        except OSError as e:
+            if e.errno != errno.ENOENT:
+                raise
+    return [filename]