First version of a check for ssh keys

diff --cc ud-mailgate
index f705497,cf82b56..94a4a71
--- 1/ud-mailgate
--- 2/ud-mailgate
+++ b/ud-mailgate
@@@ -1,13 -1,9 +1,14 @@@
  #!/usr/bin/env python
  # -*- mode: python -*-
 -import userdir_gpg, userdir_ldap, sys, traceback, time, ldap, os;
 -import pwd
 -from userdir_gpg import *;
 -from userdir_ldap import *;
 +
 +#   Prior copyright probably rmurray, troup, joey, jgg -- weasel 2008
 +#   Copyright (c) 2008 Peter Palfrader <peter@palfrader.org>
++#   Copyright (c) 2008 Joerg Jaspert <joerg@debian.org>
 +
- import userdir_gpg, userdir_ldap, sys, traceback, time, ldap, os;
- import pwd
- from userdir_gpg import *;
- from userdir_ldap import *;
++import userdir_gpg, userdir_ldap, sys, traceback, time, ldap, os, commands
++import pwd, tmpfile
++from userdir_gpg import *
++from userdir_ldap import *
  
  # Error codes from /usr/include/sysexits.h
  ReplyTo = ConfModule.replyto;
@@@ -15,6 -11,6 +16,7 @@@ PingFrom = ConfModule.pingfrom
  ChPassFrom = ConfModule.chpassfrom;
  ChangeFrom = ConfModule.changefrom;
  ReplayCacheFile = ConfModule.replaycachefile;
++SSHFingerprintFile = ConfModule.fingerprintfile
  
  EX_TEMPFAIL = 75;
  EX_PERMFAIL = 65;      # EX_DATAERR
@@@ -27,6 -23,6 +29,8 @@@ mailWhitelist = {
  SeenList = {}
  DNS = {}
  
++SSHFingerprint = re.compile('^(\d+) ([0-9a-f\:]{47}) (.+)$')
++
  ArbChanges = {"c": "..",
              "l": ".*",
              "facsimileTelephoneNumber": ".*",
@@@ -218,16 -212,16 +222,46 @@@ def DoPosition(Str,Attrs)
     Attrs.append((ldap.MOD_REPLACE,"longitude",sLong));
     return "Position set to %s/%s (%s/%s decimal degrees)"%(sLat,sLong,Lat,Long);
  
++# Load bad ssh fingerprints
++def LoadBadSSH():
++   f = open(SSHFingerprintFile, "r")
++   bad = []
++   FingerprintLine = re.compile('^([0-9a-f\:]{47}).*$')
++   for line in f.readlines():
++      Match = FingerprintLine.match(line)
++      if Match is not None:
++         g = Match.groups()
++         bad.append(g[0])
++   return bad
++
  # Handle an SSH authentication key, the line format is:
  #  [options] 1024 35 13188913666680[..] [comment]
--def DoSSH(Str,Attrs):
++def DoSSH(Str,Attrs, badkeys):
     Match = SSH2AuthSplit.match(Str);
     if Match == None:
        Match = re.compile('^1024 (\d+) ').match(Str)
        if Match is not None:
           return "SSH1 keys not supported anymore"
        return None;
--   
++
++   (fd, path) = tempfile.mkstemp("", "sshkeytry")
++   f = open(path, "w")
++   f.write(Str)
++   f.close
++   (result, output) = commands.getstatusoutput("ssh-keygen -f %s -l" % (path))
++   os.remove(path)
++   if (result != 0):
++      sys.stderr.write("ssh-keygen -l invocation failed!\n%s\n" % (output))
++      sys.exit(result)
++
++   Match = SSHFingerprint.match(output)
++
++   g = Match.groups()
++   if (g[0] < 1024):
++      return "SSH keys must have at least 1024 bits, not added"
++   elif g[0] in badkeys:
++      return "Submitted SSH Key known to be bad and insecure, not added"
++
     global SeenKey;
     if SeenKey:
       Attrs.append((ldap.MOD_ADD,"sshRSAAuthKey",Str));
@@@ -371,11 -319,11 +405,12 @@@ def HandleChange(Reply,DnRecord,Key)
        try:
           if Line == "show":
             Show = 1;
--         Res = "OK";
++           Res = "OK";
           else:
--           Res = DoPosition(Line,Attrs) or DoDNS(Line,Attrs,DnRecord) or \
--                 DoArbChange(Line,Attrs) or DoSSH(Line,Attrs) or \
--               DoDel(Line,Attrs) or DoRBL(Line,Attrs);
++            badkeys = LoadBadSSH()
++            Res = DoPosition(Line,Attrs) or DoDNS(Line,Attrs,DnRecord) or \
++                  DoArbChange(Line,Attrs) or DoSSH(Line,Attrs,badkeys) or \
++                  DoDel(Line,Attrs) or DoRBL(Line,Attrs)
        except:
           Res = None;
           Result = Result + "==> %s: %s\n" %(sys.exc_type,sys.exc_value);

diff --cc userdir-ldap.conf
index 048e907,048e907..d3a37bb
--- 1/userdir-ldap.conf
--- 2/userdir-ldap.conf
+++ b/userdir-ldap.conf
@@@ -24,6 -24,6 +24,7 @@@ changefrom = "change@" + maildomain
  templatesdir = "/etc/userdir-ldap/templates/";
  replaycachefile = "/var/cache/userdir-ldap/mail/replay";
  #replaycachefile = "/tmp/replay";
++fingerprintfile = "/etc/userdir-ldap/badfingerprints"
  
  # Echelon
  ech_errorlog = "/org/db.debian.org/mail/Log/ech-errors.log"