From de0e8d27d62c1b21b644444f1c9582e9a6649019 Mon Sep 17 00:00:00 2001
From: Fredrik Wahlberg <fredrik@wahlberg.se>
Date: Fri, 23 Jan 2004 12:59:17 +0000
Subject: [PATCH] Better catching of specific exceptions instead of try:
 except: Added verification of password/keyname

---
 dnsupdate.py | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/dnsupdate.py b/dnsupdate.py
index fe7fe68..0cce750 100644
--- a/dnsupdate.py
+++ b/dnsupdate.py
@@ -156,9 +156,14 @@ def update(msg):
   import dns.tsigkeyring
   import dns.update
   # The name of the key and the secret
-  keyring = dns.tsigkeyring.from_text({
+  import binascii # for exception handling
+  try: 
+    keyring = dns.tsigkeyring.from_text({
       msg['keyname']: msg['keysecret']
-  })
+    })
+  except binascii.Error:
+    msg['error'].append("Your password is incorrect.")
+    return 
 
   # dns.update.Update(name of domain, keyring, keyname)
   update = dns.update.Update(msg['domain'], keyring=keyring, keyname=msg['keyname'])
@@ -170,11 +175,15 @@ def update(msg):
     update.replace(msg['hostname'], msg['ttl'], 'a', msg['ipaddress'])
 
   # doit, servername
+  import socket # Import socket so we can catch exceptions
   try: 
     response = dns.query.tcp(update, '217.78.32.198')
-  except:
+  except socket.error:
     msg['error'].append("An error occurred in the server communication.")
     return 
+  except dns.tsig.BadSignature:
+    msg['error'].append("Your password could not be verified.\n       Check your password and keyname.")
+    return
  
   # Verify response
   if not msg.has_key('quiet'):
@@ -183,8 +192,10 @@ def update(msg):
         print "Host '%s.%s' has been deleted" % (msg['hostname'], msg['domain'])
       else:
         print "Host '%s.%s' has been added with ip address %s" % (msg['hostname'], msg['domain'], msg['ipaddress'])
+    elif response.rcode() == 5:
+      msg['error'].append("The server refused to accept the update")
     else:
-      print "An error has occurred, the server returned:\n%s" % response
+      msg['error'].append("Update refused, the server returned:\n%s" % response)
 
 
 
@@ -211,12 +222,16 @@ def validate(msg):
 def verify_ip(msg):
   # Check if the ip address exists and if it needs an update
   import dns.resolver
+  ip = ""
+  host = msg['hostname'] + "." + msg['domain']
   try:
-    ans = dns.resolver.query(msg['hostname'] + "." + msg['domain'], 'A')
+    ans = dns.resolver.query(host, 'A')
     for res in ans:
       ip = res.to_text()
-  except:
-    ip = ""
+  except dns.exception.Timeout:
+    msg['error'].append("Connection timeout, could not connect to nameserver.\n")
+  except dns.resolver.NXDOMAIN:
+    pass
   
   if ip == msg['ipaddress'] and not msg.has_key('delete'):
     msg['error'].append("Nameserver already up to date")