Added simple error message handling

More sanity checks
Restructured code

TODO

@@ -9,6 +9,8 @@ TODO for dnsupdate
 
 
 Done:
+- Validate data, check for cfg files existance
+- Re-structure the code
 - Add a config-file for hostname, domain and password. Option to select
   All options should be configurable, ttl and force as well. 
 - Fix the global variabel mess!!

dnsupdate.py

@@ -2,16 +2,31 @@
 # dnsupdate.py
 # Updates a dynamic dns-record using a TSIG key.
 
+def checkerror(msg):
+  if len(msg['error']) > 0:
+    for error in msg['error']:
+      print "Error: %s" % error
+    print "Use -h for help"
+    return 1
+  else:
+    return 0
+
+
 def get_ipaddress():
-  # Connects to the dns server to determine which ip address
+  # Connect to the dns server to determine which ip address
   # this host connects from
   import urllib
   remote = opener = urllib.FancyURLopener({})
-  f = opener.open("http://www.wahlberg.se/~fredrik/ip.php")
+  try:
-  ip = f.read().strip()
+    f = opener.open("http://www.wahlberg.se/~fredrik/ip.php")
-  return ip
+    ip = f.read().strip()
+    return ip
+  except:
+    msg['error'].append("Could not determine ip address automatically,\nuse -i switch to enter manually")
 
-def main(msg):
+
+
+def getparams(msg):
   from optparse import OptionParser
   import sys
   # Define option parameters
@@ -19,10 +34,10 @@ def main(msg):
   parser = OptionParser(usage)
   parser.add_option("-c", "--config", 
                     type="string",
-                    help="File containing configuration data")
+                    help="Alternate config file")
   parser.add_option("-d", "--domain", 
                     type="string",
-                    help="Name of the domain to update")
+                    help="Domain to update")
   parser.add_option("-i", "--ipaddress", 
                     type="string",
                     help="IP-address of the host [auto detected]")
@@ -31,13 +46,14 @@ def main(msg):
                     help="Name of the TSIG key")
   parser.add_option("-n", "--name", 
                     type="string",
-                    help="Name of the host to update")
+                    help="Hostname of local machine")
   parser.add_option("-p", "--password", 
                     type="string",
-                    help="The TSIG key")
+                    help="TSIG key")
   parser.add_option("-t", "--ttl", 
                     type="int",
                     help="TTL in seconds")
+                    
   (options, args) = parser.parse_args()
   
   if options.config:
@@ -45,12 +61,15 @@ def main(msg):
 
   msg = readcfg(msg)
   
-  if options.domain:
-    msg['domain'] = options.domain
   if options.ipaddress:
     msg['ipaddress'] = options.ipaddress
   else:
-    msg['ipaddress'] = get_ipaddress()
+    ip = get_ipaddress()
+    if ip:
+      msg['ipaddress'] = ip
+
+  if options.domain:
+    msg['domain'] = options.domain
   if options.keyname:
     msg['keyname'] = options.keyname
   if options.name:
@@ -60,13 +79,23 @@ def main(msg):
   if options.ttl:
     msg['ttl'] = options.ttl
   
-  #print msg
+  return msg
-  update(msg)
+
 
 
 def readcfg(msg):
+  import os.path
   # Reads the config file for default info
-  cfgfile = open(msg['cfgfile'], 'r')
+  if not msg.has_key('cfgfile'):
+    if os.path.exists(os.path.expanduser("~/.dnsupdaterc")):
+      cfgfile = open(os.path.expanduser("~/.dnsupdaterc"), 'r')
+    else:
+      return msg
+  else:
+    if not os.path.exists(msg['cfgfile']):
+      msg['error'].append("No such file: %s" % msg['cfgfile'])
+      return msg
+    cfgfile = open(msg['cfgfile'], 'r')
 
   for line in cfgfile.readlines():
     (key, value) = line.split('\t', 1)
@@ -75,22 +104,14 @@ def readcfg(msg):
   cfgfile.close()
   return msg
 
+
+
 def update(msg):
   import dns.query
   import dns.tsigkeyring
   import dns.update
-  import re
-  import string
   # The update function connects to the dns server
   
-  # Sanity check incoming data
-  #global hostname, ipaddress, ttl
-  msg['hostname'] = string.replace(msg['hostname'], "." + msg['domain'], '')
-  if not re.search('^[12]?[0-9]?[0-9](\.[12]?[0-9]?[0-9]){3}$', msg['ipaddress']):
-    print "Invalid ip address '%s'" % msg['ipaddress']
-    return
-  
-
   # The name of the key and the secret
   keyring = dns.tsigkeyring.from_text({
       msg['keyname']: msg['keysecret']
@@ -103,7 +124,11 @@ def update(msg):
   update.replace(msg['hostname'], msg['ttl'], 'a', msg['ipaddress'])
 
   # doit, servername
-  response = dns.query.tcp(update, 'nic.wahlberg.se')
+  try: 
+    response = dns.query.tcp(update, '217.78.32.198')
+  except:
+    msg['error'].append("An error has occurred, check your keyname and password.")
+    return 
   
   # Verify response
   if response.rcode() == 0:
@@ -111,8 +136,36 @@ def update(msg):
   else:
     print "An error has occurred, the server returned:\n%s" % response
 
+
+
+def validate(msg):
+  import re
+  import string
+  # Verify all required data is present and sanity check incoming data
+  req_vals = ['domain', 'hostname', 'ipaddress', 'keyname', 'keysecret']
+  for value in req_vals:
+    if not msg.has_key(value):
+      msg['error'].append('Missing "%s" parameter' % value)
+  
+  #global hostname, ipaddress, ttl
+  if msg.has_key('hostname') and msg.has_key('domain'):
+    msg['hostname'] = string.replace(msg['hostname'], "." + msg['domain'], '')
+  
+  if msg.has_key('ipaddress'):
+    if not re.search('^[12]?[0-9]?[0-9](\.[12]?[0-9]?[0-9]){3}$', msg['ipaddress']):
+      msg['error'].append("Invalid ip address '%s'" % msg['ipaddress'])
+
+  return msg  
+
+
+
 if __name__=="__main__":
-  import os.path
   msg = {}
-  msg['cfgfile'] = os.path.expanduser("~/.dnsupdaterc")
+  msg['error'] = []
-  main(msg)
+
+  getparams(msg)
+  validate(msg)
+  err = checkerror(msg)
+  if err == 0:
+    update(msg)
+    checkerror(msg)