signature checking changes

Adjust the gpgv signature check. Add one more case of broken key to detect,
EXPKEYSIG. From gnupg docs:
    EXPKEYSIG   <long keyid>  <username>
    The signature with the keyid is good, but the signature was
    made by an expired key. The username is the primary one
    encoded in UTF-8 and %XX escaped.

Also, handle KEYEXPIRED right. The first argument given back is NOT the keyid,
it is the timestamp when the key expired. From gnupg docs:
    KEYEXPIRED <expire-timestamp>
    The key has expired.  expire-timestamp is the expiration time
    in seconds after the epoch.

    Note, that TIMESTAMP may either be a number with seconds since
    epoch or an ISO 8601 string which can be detected by the
    presence of the letter 'T' inside.
So lets go and see if we find a T, if not convert the epoch to something
more easily human readable in our reject message.
Signed-off-by: NJoerg Jaspert <joerg@debian.org>

daklib/utils.py

@@ -26,6 +26,7 @@ import codecs, commands, email.Header, os, pwd, re, select, socket, shutil, \
        sys, tempfile, traceback, stat
 import apt_pkg
 import database
+import time
 from dak_exceptions import *
 
 ################################################################################
@@ -1231,11 +1232,22 @@ used."""
     if keywords.has_key("NODATA"):
         reject("no signature found in %s." % (sig_filename))
         bad = 1
+    if keywords.has_key("EXPKEYSIG"):
+        args = keywords["EXPKEYSIG"]
+        if len(args) >= 1:
+            key = args[0]
+        reject("Signature made by expired key x%s" % (key))
+        bad = 1
     if keywords.has_key("KEYEXPIRED") and not keywords.has_key("GOODSIG"):
         args = keywords["KEYEXPIRED"]
+        expiredate=""
         if len(args) >= 1:
-            key = args[0]
-        reject("The key (0x%s) used to sign %s has expired." % (key, sig_filename))
+            timestamp = args[0]
+            if timestamp.count("T") == 0:
+                expiredate = time.strftime("%Y-%m-%d", time.gmtime(timestamp))
+            else:
+                expiredate = timestamp
+        reject("The key used to sign %s has expired on %s" % (sig_filename, expiredate))
         bad = 1
 
     if bad: