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samba-tool dns: move dns_record_match to dnsserver.py
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This function is used here and in tests, but the tests should not be
importing things from netcmd.dns, which is really supposed to be UI
code. So we move to a common place.

the only difference is the function raises DNSParseError instead of
CommandError, and netcmd.dns has to catch and wrap that.

Signed-off-by: Douglas Bagnall <[email protected]>
Reviewed-by: Andrew Bartlett <[email protected]>
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douglasbagnall committed Jun 2, 2021
1 parent 537f2d1 commit eeaa138
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Showing 3 changed files with 99 additions and 83 deletions.
91 changes: 91 additions & 0 deletions python/samba/dnsserver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -295,3 +295,94 @@ def flag_from_string(rec_type):
return getattr(dnsp, 'DNS_TYPE_' + rtype)
except AttributeError:
raise DNSParseError('Unknown type of DNS record %s' % rec_type) from e


def dns_name_equal(n1, n2):
"""Match dns name (of type DNS_RPC_NAME)"""
return n1.str.rstrip('.').lower() == n2.str.rstrip('.').lower()


def dns_record_match(dns_conn, server, zone, name, record_type, data):
"""Find a dns record that matches the specified data"""

# The matching is not as precises as that offered by
# dsdb_dns.match_record, which, for example, compares IPv6 records
# semantically rather than as strings. However that function
# compares database DnssrvRpcRecord structures, not wire
# DNS_RPC_RECORD structures.
#
# While it would be possible, perhaps desirable, to wrap that
# function for use in samba-tool, there is value in having a
# separate implementation for tests, to avoid the circularity of
# asserting the function matches itself.

urec = record_from_string(record_type, data)

select_flags = dnsserver.DNS_RPC_VIEW_AUTHORITY_DATA

try:
buflen, res = dns_conn.DnssrvEnumRecords2(
dnsserver.DNS_CLIENT_VERSION_LONGHORN, 0, server, zone, name, None,
record_type, select_flags, None, None)
except WERRORError as e:
if e.args[0] == werror.WERR_DNS_ERROR_NAME_DOES_NOT_EXIST:
# Either the zone doesn't exist, or there were no records.
# We can't differentiate the two.
return None
raise e

if not res or res.count == 0:
return None

for rec in res.rec[0].records:
if rec.wType != record_type:
continue

found = False
if record_type == dnsp.DNS_TYPE_A:
if rec.data == urec.data:
found = True
elif record_type == dnsp.DNS_TYPE_AAAA:
if rec.data == urec.data:
found = True
elif record_type == dnsp.DNS_TYPE_PTR:
if dns_name_equal(rec.data, urec.data):
found = True
elif record_type == dnsp.DNS_TYPE_CNAME:
if dns_name_equal(rec.data, urec.data):
found = True
elif record_type == dnsp.DNS_TYPE_NS:
if dns_name_equal(rec.data, urec.data):
found = True
elif record_type == dnsp.DNS_TYPE_MX:
if dns_name_equal(rec.data.nameExchange, urec.data.nameExchange) and \
rec.data.wPreference == urec.data.wPreference:
found = True
elif record_type == dnsp.DNS_TYPE_SRV:
if rec.data.wPriority == urec.data.wPriority and \
rec.data.wWeight == urec.data.wWeight and \
rec.data.wPort == urec.data.wPort and \
dns_name_equal(rec.data.nameTarget, urec.data.nameTarget):
found = True
elif record_type == dnsp.DNS_TYPE_SOA:
if rec.data.dwSerialNo == urec.data.dwSerialNo and \
rec.data.dwRefresh == urec.data.dwRefresh and \
rec.data.dwRetry == urec.data.dwRetry and \
rec.data.dwExpire == urec.data.dwExpire and \
rec.data.dwMinimumTtl == urec.data.dwMinimumTtl and \
dns_name_equal(rec.data.NamePrimaryServer,
urec.data.NamePrimaryServer) and \
dns_name_equal(rec.data.ZoneAdministratorEmail,
urec.data.ZoneAdministratorEmail):
found = True
elif record_type == dnsp.DNS_TYPE_TXT:
if rec.data.count == urec.data.count:
found = True
for i in range(rec.data.count):
found = found and \
(rec.data.str[i].str == urec.data.str[i].str)

if found:
return rec

return None
88 changes: 7 additions & 81 deletions python/samba/netcmd/dns.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@
from samba.dcerpc import dnsp, dnsserver

from samba.dnsserver import record_from_string, DNSParseError, flag_from_string
from samba.dnsserver import dns_record_match


def dns_connect(server, lp, creds):
Expand Down Expand Up @@ -394,85 +395,6 @@ def data_to_dns_record(record_type, data):
return rec


# Match dns name (of type DNS_RPC_NAME)
def dns_name_equal(n1, n2):
return n1.str.rstrip('.').lower() == n2.str.rstrip('.').lower()


# Match a dns record with specified data
def dns_record_match(dns_conn, server, zone, name, record_type, data):
urec = data_to_dns_record(record_type, data)

select_flags = dnsserver.DNS_RPC_VIEW_AUTHORITY_DATA

try:
buflen, res = dns_conn.DnssrvEnumRecords2(
dnsserver.DNS_CLIENT_VERSION_LONGHORN, 0, server, zone, name, None,
record_type, select_flags, None, None)
except WERRORError as e:
if e.args[0] == werror.WERR_DNS_ERROR_NAME_DOES_NOT_EXIST:
# Either the zone doesn't exist, or there were no records.
# We can't differentiate the two.
return None
raise e

if not res or res.count == 0:
return None

for rec in res.rec[0].records:
if rec.wType != record_type:
continue

found = False
if record_type == dnsp.DNS_TYPE_A:
if rec.data == urec.data:
found = True
elif record_type == dnsp.DNS_TYPE_AAAA:
if rec.data == urec.data:
found = True
elif record_type == dnsp.DNS_TYPE_PTR:
if dns_name_equal(rec.data, urec.data):
found = True
elif record_type == dnsp.DNS_TYPE_CNAME:
if dns_name_equal(rec.data, urec.data):
found = True
elif record_type == dnsp.DNS_TYPE_NS:
if dns_name_equal(rec.data, urec.data):
found = True
elif record_type == dnsp.DNS_TYPE_MX:
if dns_name_equal(rec.data.nameExchange, urec.data.nameExchange) and \
rec.data.wPreference == urec.data.wPreference:
found = True
elif record_type == dnsp.DNS_TYPE_SRV:
if rec.data.wPriority == urec.data.wPriority and \
rec.data.wWeight == urec.data.wWeight and \
rec.data.wPort == urec.data.wPort and \
dns_name_equal(rec.data.nameTarget, urec.data.nameTarget):
found = True
elif record_type == dnsp.DNS_TYPE_SOA:
if rec.data.dwSerialNo == urec.data.dwSerialNo and \
rec.data.dwRefresh == urec.data.dwRefresh and \
rec.data.dwRetry == urec.data.dwRetry and \
rec.data.dwExpire == urec.data.dwExpire and \
rec.data.dwMinimumTtl == urec.data.dwMinimumTtl and \
dns_name_equal(rec.data.NamePrimaryServer,
urec.data.NamePrimaryServer) and \
dns_name_equal(rec.data.ZoneAdministratorEmail,
urec.data.ZoneAdministratorEmail):
found = True
elif record_type == dnsp.DNS_TYPE_TXT:
if rec.data.count == urec.data.count:
found = True
for i in range(rec.data.count):
found = found and \
(rec.data.str[i].str == urec.data.str[i].str)

if found:
return rec

return None


class cmd_serverinfo(Command):
"""Query for Server information."""

Expand Down Expand Up @@ -1016,8 +938,12 @@ def run(self, server, zone, name, rtype, olddata, newdata,
self.creds = credopts.get_credentials(self.lp)
dns_conn = dns_connect(server, self.lp, self.creds)

rec_match = dns_record_match(dns_conn, server, zone, name, record_type,
olddata)
try:
rec_match = dns_record_match(dns_conn, server, zone, name, record_type,
olddata)
except DNSParseError as e:
raise CommandError(*e.args) from None

if not rec_match:
raise CommandError('Record or zone does not exist.')

Expand Down
3 changes: 1 addition & 2 deletions python/samba/tests/dns.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,8 +29,7 @@
from samba import credentials
from samba.dcerpc import dns, dnsp, dnsserver
from samba.dnsserver import TXTRecord
from samba.dnsserver import record_from_string
from samba.netcmd.dns import dns_record_match
from samba.dnsserver import record_from_string, dns_record_match
from samba.tests.subunitrun import SubunitOptions, TestProgram
from samba import werror, WERRORError
from samba.tests.dns_base import DNSTest
Expand Down

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