root/trunk/misc/dns-o-matic.py

#!/usr/bin/python

# This script attempts to discover DNS configuration errors and inconsistencies between servers on your
# coporate network. Run the script with stdout redirected to a file to generate a nice HTML report.
# Example usage:
#   $ ./dns-o-matic.py > report.html
#
# This script requires the python DNS and netaddr modules, which are
# probably already available in your favourite Linux distribution.
# From Ubuntu:
#   $ apt-get install python-dns python-netaddr
# From Fedora:
#   $ yum install python-pydns python-netaddr


import sys
import DNS
from netaddr import IPNetwork, IPAddress
from pprint import PrettyPrinter

DNS.DiscoverNameServers()


def Request(domain,type,nameserver=None):
    # try this upto three times because sometimes the connection to slovakia times out
    for retry in range(3):
        try:
            if nameserver == None:
                return DNS.Request(domain,qtype=type,timeout=10).req()
            else:
                return DNS.Request(domain,qtype=type,server=nameserver,timeout=10).req()
        except DNS.Error:
            if retry == 2:
                return None


def RecursiveLookup(data,rec_lookup,type,nameserver,astart=None,ptrstart=None):
    # exit when a request loop is detected
    if type == 'PTR':
        if ptrstart == None:
            ptrstart = rec_lookup
        elif ptrstart == rec_lookup:
            return
        else:
            ptrstart = rec_lookup
    else:
        if astart == None:
            astart = rec_lookup
        elif astart == rec_lookup:
            return
        else:
            astart = rec_lookup

    r = None
    if type == 'PTR':
        # reverse lookup request gives you all the hostnames that the given ip address resolves to
        rec = IPAddress(rec_lookup)
        r = Request(rec.reverse_dns,type,nameserver)
    else:
        # forward lookup request gives you all the ip addresses that the given hostname resolves to
        r = Request(rec_lookup,type,nameserver)

    # we shouldn't ever time out
    if r == None:
        sys.stderr.write("ERROR: Timed out querying for %s records from %s\n" % (type, nameserver))
        sys.exit(1)

    # loop through all the answers
    if r.header['status'] == 'NOERROR':
        for rec_result,rec_type in [(x['data'],x['type']) for x in r.answers]:

            # despite only ever asking for PTR or A records, we sometimes get CNAMEs, so discard them
            if rec_type not in set([DNS.Type.A, DNS.Type.PTR]):
                continue

            # add to the list of answers
            answer = {
                      'ns'          : nameserver,
                      'lookup_of'   : rec_lookup,
                      'lookup_type' : type,
                      'resolves_to' : rec_result,
                      'status'      : r.header['status'],
                      'subrecords'  : [],
                      'problems'    : [],
                      }
            data.append(answer)

            # rinse and repeat
            if type == 'PTR':
                RecursiveLookup(answer['subrecords'],rec_result,'A',  nameserver,astart,ptrstart)
            else:
                RecursiveLookup(answer['subrecords'],rec_result,'PTR',nameserver,astart,ptrstart)
    else:
        # add the error to the list of answers
        answer = {
                  'ns'          : nameserver,
                  'lookup_of'   : rec_lookup,
                  'lookup_type' : type,
                  'resolves_to' : '',
                  'status'      : r.header['status'],
                  'subrecords'  : [],
                  'problems'    : [],
                  }
        data.append(answer)


def GetNameServers(domain):
    # start of authority request gives you the primary nameserver for a given domain
    r = Request(domain,'SOA')
    if r.header['status'] != 'NOERROR':
        sys.stderr.write("ERROR: Received status of %s when attempting to query for SOA records\n" % (r.header['status']))
        sys.exit(1)
    primary,email,serial,refresh,retry,expire,minimum = r.answers[0]['data']

    # name server request on the primary name server gives you all the name servers for a given domain
    r = Request(domain,'NS',primary)
    if r.header['status'] != 'NOERROR':
        sys.stderr.write("ERROR: Received status of %s when attempting to query for NS records\n" % (r.header['status']))
        sys.exit(1)
    return [(x['data'],x['data']==primary) for x in r.answers]


def PrintNameServers(domain,nameservers):
    print "<p>Available nameservers for %s:</p>" % domain
    print "<ul>"
    for ns,pri in nameservers:
        if pri:
            print "<li>%s - primary (holds the start of authority record)</li>" % ns
        else:
            print "<li>%s</li>" % ns
    print "</ul>"


#def FindValidLoops(data):
#   # do a depth-first search for request loops and mark these records as valid
#   num = 0
#   for result in data['results']:
#       new_num = FindValidLoops(result)
#       if new_num > num:
#           num = new_num
#   if not data['status']:
#       data['valid'] = True
#       return 2
#   else:
#       if num > 0:
#           data['valid'] = True
#           return num - 1
#       else:
#           data['valid'] = False
#           return 0


def FindDanglingPointers(data):
    for rec in data['subrecords']:
        if rec['status'] == 'NXDOMAIN':
            problem = {
                       'icon':'error',
                       'text':'Dangling pointer (PTR) record detected for %s! \n\n' % data['lookup_of'] + \
                              'Perhaps it was left behind when the address (A) record for %s was deleted.' % data['resolves_to'],
                       }
            rec['problems'].append(problem)


def GetSubnetAnalysis(nameservers,subnet):
    data = {'subnet':str(subnet), 'nameservers':[], 'addresses':[]}

    # make a note of which is the primary nameserver
    primary = ''
    for ns,pri in nameservers:
        data['nameservers'].append({'name':ns, 'primary':pri})
        if pri:
            primary = ns

    # iterate through all valid addresses in the subnet
    sys.stderr.write("Processing Subnet: %s\n" % str(subnet))
    for ip in [str(x) for x in list(subnet) if x != subnet.broadcast and x != subnet.ip]:
        sys.stderr.write(".")

        # request the crap out of the DNS servers
        address = {'ip':ip, 'results':[]}
        for ns,pri in nameservers:
            RecursiveLookup(address['results'],ip,'PTR',ns)

        # forget about addresses that don't have records in *any* nameservers
        for result in address['results']:
            if result['status'] != 'NXDOMAIN':
                data['addresses'].append(address)
                break
    sys.stderr.write("\n")

    # detect dangling pointers
    for address in data['addresses']:
        for result in address['results']:
            FindDanglingPointers(result)
    return data


def RecursivePrintResults(data,level=0):
    # display the record we're looking up
    if data['resolves_to'] != '':
        print "    <p style='padding-left:%spx'><span class='record'>%s</span> resolves to <span class='record'>%s</span>" % (`level * 20`, data['lookup_of'], data['resolves_to'])
    else:
        print "    <p style='padding-left:%spx'><span class='record'>%s</span> does not resolve to anything!" % (`level * 20`, data['lookup_of'])

    # display any problems associated with the record
    for prob in data['problems']:
        print "      <a rel='tooltip' title='%s'>" % prob['text']
        print "        <img src='icons/%s.png' alt='%s' />" % (prob['icon'], prob['icon'])
        print "      </a>"
    print "    </p>"

    # recursively display subrecords
    if len(data['subrecords']) > 0:
        for rec in data['subrecords']:
            RecursivePrintResults(rec,level + 1)


def PrintSubnetAnalysis(data):
    subnet_id = "subnet-" + data['subnet'].replace('/','-').replace('.','-')
    print "<h2 id='%s_heading'>Analysis of the %s subnet</h2>" % (subnet_id, data['subnet'])
    print "<p><a class='debugs_on'  id='%s_on'  href='#%s_heading'>Show Debugs</a>" % (subnet_id, subnet_id) + \
             "<a class='debugs_off' id='%s_off' href='#%s_heading'>Hide Debugs</a></p>" % (subnet_id, subnet_id)
    print "<table id='%s_table' border='1'>" % subnet_id

    heading = "<tr><th>address</th>"
    for ns in data['nameservers']:
        if ns['primary']:
            heading += "<th>%s (SOA)</th>" % ns['name']
        else:
            heading += "<th>%s</th>" % ns['name']
    heading += "</tr>"

    for i,address in enumerate(data['addresses']):
        if i % 25 == 0:
            print heading
        print "<tr>\n  <td><p>%s</p></td>" % address['ip']
        for ns in data['nameservers']:
            print "  <td>"
            for result in [x for x in address['results'] if x['ns'] == ns['name']]:
                RecursivePrintResults(result)
            print "  </td>"
        print "</tr>"
    print "</table>"

    # print the raw data structure for debugging
    print "<pre id='%s_debugs' style='display:none;'>" % subnet_id
    pp = PrettyPrinter(indent=2)
    pp.pprint(data)
    print "</pre>"


print """
<html>
<head>
  <title>DNS-o-Matic Report</title>
  <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>
  <script type="text/javascript">
    jQuery(document).ready(function($) {
      /* display the show debugs buttons by default */
      $("a.debugs_on").css('display', 'inline');

      /* show debugs button click event callback */
      $("a.debugs_on").click(function() {
        var subnet = "#" + $(this).attr('id').split('_')[0];
        $(subnet+"_debugs").css('display', 'block');
        $(subnet+"_table").css('display', 'none');
        $(subnet+"_on").css('display', 'none');
        $(subnet+"_off").css('display', 'inline');
      });

      /* hide debugs button click event callback */
      $("a.debugs_off").click(function() {
        var subnet = "#" + $(this).attr('id').split('_')[0];
        $(subnet+"_debugs").css('display', 'none');
        $(subnet+"_table").css('display', 'table');
        $(subnet+"_on").css('display', 'inline');
        $(subnet+"_off").css('display', 'none');
      });

      /* mouseover tooltip event callbacks */
      $('a[rel=tooltip]').mouseover(function(e) {
        /* steal the title text to use in the tooltip */
        var msg = $(this).attr('title').replace('\n','<br />');
        $(this).attr('title','');
        /* construct the tooltip */
        $(this).append('<div id="tooltip"><div class="tooltipBody">' + msg + '</div></div>');
        /* position and show the tooltip */
        $("#tooltip").css('top', e.pageY + 10 );
        $("#tooltip").css('left', e.pageX + 20 );
      }).mousemove(function(e) {
        /* make the tooltip follow the cursor */
        $("#tooltip").css('top', e.pageY + 10 );
        $("#tooltip").css('left', e.pageX + 20 );
      }).mouseout(function() {
        /* put the title text back and destroy the tooltip */
        $(this).attr('title',$(".tooltipBody").html());
        $(this).children("div#tooltip").remove();
      });
    });
  </script>
  <style>
    th {
      font-family:sans-serif;
      padding:5px 0px;
    }
    td {
      font-family:sans-serif;
      font-weight:normal;
      font-size:0.8em;
      color:#666;
      padding:5px;
    }
    td p {
      margin:0;
      padding:0;
    }
    img {
      height:0.8em;
      border:0;
    }
    #tooltip {
        position:absolute;
        z-index:9999;
        color:#fff;
        font-size:10px;
        width:275px;
    }
    #tooltip .tooltipBody {
      background-color:#000;
      padding:5px
    }
    .record {
      font-weight:bold;
      color:black;
    }
    .debugs_on, .debugs_off {
      display:none;
    }
  </style>
</head>
<body>
<h1>DNS-o-Matic Report</h1>
"""

domain = 'cse-servelec.com'
subnets = [
           IPNetwork('194.62.153.0/24'),
           IPNetwork('194.62.154.0/24'),
           ]

nslist = GetNameServers(domain)
PrintNameServers(domain,nslist)
for subnet in subnets:
    analysis = GetSubnetAnalysis(nslist, subnet)
    PrintSubnetAnalysis(analysis)

print """
</body>
</html>
"""