#  dnsRegRec-0.8.py  8/15/05  David MacQuigg
#
import DNS  # from pydns.sourceforge.net

from DNS import DNSError

class Timeout(DNSError):
    "Special handling for timeouts"
class NoRecord(DNSError):
    "Special handliing for missing records"

DNSTimeout = 5

def getTXT(name):
    '''Get a single TXT record, which might have multiple strings, and return
    one long string.  Raise 'Timeout' for DNS timeout errors, 'NoRecord' for
    no TXT records or non-existent domain, and DNSError for all other errors.

    Raise a DNSError if the number of TXT records is greater than one.
    
    >>> getTXT('simple.tld.id.open-mail.org')
    'svc=S1:A,M2:A,H1:B ip4=192.168.0.0/29'

    >>> getTXT('nonexistent.tld.id.open-mail.org')
    Traceback (most recent call last):
       - - -
    NoRecord: No TXT record for 'nonexistent.tld.id.open-mail.org'.
    
    '''
    if name == 'example.com.id.open-mail.org':  # stub for local testing
        return "svc=S1:A,H1:B ip4=192.168.0.0/16"
    
    try:
        reqobj = DNS.Request(name, qtype='TXT', timeout=DNSTimeout)
        resp = reqobj.req()

    except DNSError, expln:
        exp = str(expln)
        if exp == 'Timeout':  raise Timeout, (
                "Timeout getting Registry record '%s'." % name )
        else:
            raise DNSError, expln
        
    lr = len(resp.answers)
    if lr == 0:  raise NoRecord, (
        "No TXT record for '%s'." % name )  # or non-existent domain
    if lr  > 1:  raise DNSError, (
        "Found %s TXT records for '%s'. Should be 1." % (lr, name) )
    
    ra0 = resp.answers[0]
    rad = ra0['data']      # list of strings, each < 255 bytes
    data = ''.join(rad)    # concatenate multiple strings
##    rdlen = ra0['rdlength']  # total length of data in first record
    return data


if __name__ == '__main__':

    ##DNS.DiscoverNameServers()  # from /etc/resolv.conf or Windows Registry
    ##                           # to DNS.defaults
    # Alternative manual setting:
    DNS.defaults['server'] = ['216.183.68.110', '216.183.68.111']

    import sys, doctest
    doctest.testmod(sys.modules['__main__'], verbose=True)

# More unit tests:
# Note: We are not running these via doctest, because there are frequent
# changes in the records, which will trigger numerous doctest discrepancies.
# Just run them and observe the normal output (quoted below).
# You can test a timeout error by setting DNSTimeout to 0.01.
   ### Note: Setting the Timeout this low causes syncronization problems.
   # Late arriving records get associated with names later in the list. !!!

    def test_getTXT(name):
        try:
            return getTXT(name)
        except DNSError, expln:
            return expln

    print 40 * '=', 'Declared IDs'
    namelist = ['simple', 'complex', 'spf-only', 'csv-only', 'rr',
            '2-strings', '2-txt', 'notxt', 'nonexistant']
    for name in namelist:
        fullname = name + '.tld.id.open-mail.org'
        record = test_getTXT(fullname)
        print fullname
        print record
        print

# Default IDs are stored in a different branch of the Registry.  Notice how
# we can have different defaults at different levels of the same ID.  Every
# server in Texas gets a default ID=rr.tld, except servers in Dallas, which
# get a default ID=texas.rr.tld.

    print 40 * '=', 'Default IDs'
    namelist = ['abilene.texas.rr.tld', 'a.b.c.dallas.texas.rr.tld']

    for name in namelist:
        fullname = name + '.df.open-mail.org'
        record = test_getTXT(fullname)
        print fullname
        print record
        print

# Default IDs can also be determined from the IP address.

    print 40 * '=', 'Default ID from IP address'
    fullname = '1.0.168.192.ip.open-mail.org'
    record = test_getTXT(fullname)
    print fullname
    print record
    print

'''
======================================== Declared IDs
simple.tld.id.open-mail.org
svc=S1:A,M2:A,H1:B ip4=192.168.0.0/29

complex.tld.id.open-mail.org
svc=S1:A,M2:A,H1+:B  meth=SPF+5,DK  SPF='v=spf1 mx include:s._spf.test.tld include:m._spf.test.tld include:p._spf.test.tld include:c._spf.test.tld ~all' DK=k=rsa;p=HwwDQYJKoZIhvcNAQEBBQADawAwaAJhAKJ2lzDLZ8XlVambQfMXn3LRGKOD5wDQYJKQYJKoZIhvcNAQEBBQADawABgc

spf-only.tld.id.open-mail.org
svc=S1:A,M2:A,H1:B meth=spf+10 spf='v=spf1 redirect=_spf.open-mail.org' 

csv-only.tld.id.open-mail.org
svc=S1:A,M2:A,H1:B meth=csv+3

rr.tld.id.open-mail.org
svc=S1:A,M2:A,H1:B meth=spf+1 spf='v=spf1 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 ip4:192.168.0.0/24 +mx ~all' 

2-strings.tld.id.open-mail.org
xxx255x89012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345xxx124x890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234

2-txt.tld.id.open-mail.org
Found 2 TXT records for '2-txt.tld.id.open-mail.org'. Should be 1.

notxt.tld.id.open-mail.org
No TXT record for 'notxt.tld.id.open-mail.org'.

nonexistant.tld.id.open-mail.org
No TXT record for 'nonexistant.tld.id.open-mail.org'.

======================================== Default IDs
abilene.texas.rr.tld.df.open-mail.org
ID=rr.tld score=5  ip4=192.0.4.0/24

a.b.c.dallas.texas.rr.tld.df.open-mail.org
ID=texas.rr.tld score=5  ip4=192.0.3.0/24

======================================== Default ID from IP address
1.0.168.192.ip.open-mail.org
ID=192.168.0.1/22  score=5

>>> 
'''