s4-python: import a copy of the python dns library

This library is not installed on enough systems for us to rely
on it being available. We use the system copy if possible, and
fallback to this local copy

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

1 files changed, 216 insertions, 0 deletions

diff --git a/source4/scripting/python/samba_external/dnspython/dns/tsig.py b/source4/scripting/python/samba_external/dnspython/dns/tsig.py
new file mode 100644
index 0000000000..b4deeca859
--- /dev/null
+++ b/source4/scripting/python/samba_external/dnspython/dns/tsig.py
@@ -0,0 +1,216 @@
+# Copyright (C) 2001-2007, 2009, 2010 Nominum, Inc.
+#
+# Permission to use, copy, modify, and distribute this software and its
+# documentation for any purpose with or without fee is hereby granted,
+# provided that the above copyright notice and this permission notice
+# appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+"""DNS TSIG support."""
+
+import hmac
+import struct
+
+import dns.exception
+import dns.rdataclass
+import dns.name
+
+class BadTime(dns.exception.DNSException):
+    """Raised if the current time is not within the TSIG's validity time."""
+    pass
+
+class BadSignature(dns.exception.DNSException):
+    """Raised if the TSIG signature fails to verify."""
+    pass
+
+class PeerError(dns.exception.DNSException):
+    """Base class for all TSIG errors generated by the remote peer"""
+    pass
+
+class PeerBadKey(PeerError):
+    """Raised if the peer didn't know the key we used"""
+    pass
+
+class PeerBadSignature(PeerError):
+    """Raised if the peer didn't like the signature we sent"""
+    pass
+
+class PeerBadTime(PeerError):
+    """Raised if the peer didn't like the time we sent"""
+    pass
+
+class PeerBadTruncation(PeerError):
+    """Raised if the peer didn't like amount of truncation in the TSIG we sent"""
+    pass
+
+default_algorithm = "HMAC-MD5.SIG-ALG.REG.INT"
+
+BADSIG = 16
+BADKEY = 17
+BADTIME = 18
+BADTRUNC = 22
+
+def sign(wire, keyname, secret, time, fudge, original_id, error,
+         other_data, request_mac, ctx=None, multi=False, first=True,
+         algorithm=default_algorithm):
+    """Return a (tsig_rdata, mac, ctx) tuple containing the HMAC TSIG rdata
+    for the input parameters, the HMAC MAC calculated by applying the
+    TSIG signature algorithm, and the TSIG digest context.
+    @rtype: (string, string, hmac.HMAC object)
+    @raises ValueError: I{other_data} is too long
+    @raises NotImplementedError: I{algorithm} is not supported
+    """
+
+    (algorithm_name, digestmod) = get_algorithm(algorithm)
+    if first:
+        ctx = hmac.new(secret, digestmod=digestmod)
+        ml = len(request_mac)
+        if ml > 0:
+            ctx.update(struct.pack('!H', ml))
+            ctx.update(request_mac)
+    id = struct.pack('!H', original_id)
+    ctx.update(id)
+    ctx.update(wire[2:])
+    if first:
+        ctx.update(keyname.to_digestable())
+        ctx.update(struct.pack('!H', dns.rdataclass.ANY))
+        ctx.update(struct.pack('!I', 0))
+    long_time = time + 0L
+    upper_time = (long_time >> 32) & 0xffffL
+    lower_time = long_time & 0xffffffffL
+    time_mac = struct.pack('!HIH', upper_time, lower_time, fudge)
+    pre_mac = algorithm_name + time_mac
+    ol = len(other_data)
+    if ol > 65535:
+        raise ValueError('TSIG Other Data is > 65535 bytes')
+    post_mac = struct.pack('!HH', error, ol) + other_data
+    if first:
+        ctx.update(pre_mac)
+        ctx.update(post_mac)
+    else:
+        ctx.update(time_mac)
+    mac = ctx.digest()
+    mpack = struct.pack('!H', len(mac))
+    tsig_rdata = pre_mac + mpack + mac + id + post_mac
+    if multi:
+        ctx = hmac.new(secret)
+        ml = len(mac)
+        ctx.update(struct.pack('!H', ml))
+        ctx.update(mac)
+    else:
+        ctx = None
+    return (tsig_rdata, mac, ctx)
+
+def hmac_md5(wire, keyname, secret, time, fudge, original_id, error,
+             other_data, request_mac, ctx=None, multi=False, first=True,
+             algorithm=default_algorithm):
+    return sign(wire, keyname, secret, time, fudge, original_id, error,
+                other_data, request_mac, ctx, multi, first, algorithm)
+
+def validate(wire, keyname, secret, now, request_mac, tsig_start, tsig_rdata,
+             tsig_rdlen, ctx=None, multi=False, first=True):
+    """Validate the specified TSIG rdata against the other input parameters.
+
+    @raises FormError: The TSIG is badly formed.
+    @raises BadTime: There is too much time skew between the client and the
+    server.
+    @raises BadSignature: The TSIG signature did not validate
+    @rtype: hmac.HMAC object"""
+
+    (adcount,) = struct.unpack("!H", wire[10:12])
+    if adcount == 0:
+        raise dns.exception.FormError
+    adcount -= 1
+    new_wire = wire[0:10] + struct.pack("!H", adcount) + wire[12:tsig_start]
+    current = tsig_rdata
+    (aname, used) = dns.name.from_wire(wire, current)
+    current = current + used
+    (upper_time, lower_time, fudge, mac_size) = \
+                 struct.unpack("!HIHH", wire[current:current + 10])
+    time = ((upper_time + 0L) << 32) + (lower_time + 0L)
+    current += 10
+    mac = wire[current:current + mac_size]
+    current += mac_size
+    (original_id, error, other_size) = \
+                  struct.unpack("!HHH", wire[current:current + 6])
+    current += 6
+    other_data = wire[current:current + other_size]
+    current += other_size
+    if current != tsig_rdata + tsig_rdlen:
+        raise dns.exception.FormError
+    if error != 0:
+        if error == BADSIG:
+            raise PeerBadSignature
+        elif error == BADKEY:
+            raise PeerBadKey
+        elif error == BADTIME:
+            raise PeerBadTime
+        elif error == BADTRUNC:
+            raise PeerBadTruncation
+        else:
+            raise PeerError('unknown TSIG error code %d' % error)
+    time_low = time - fudge
+    time_high = time + fudge
+    if now < time_low or now > time_high:
+        raise BadTime
+    (junk, our_mac, ctx) = sign(new_wire, keyname, secret, time, fudge,
+                                original_id, error, other_data,
+                                request_mac, ctx, multi, first, aname)
+    if (our_mac != mac):
+        raise BadSignature
+    return ctx
+
+def get_algorithm(algorithm):
+    """Returns the wire format string and the hash module to use for the
+    specified TSIG algorithm
+
+    @rtype: (string, hash constructor)
+    @raises NotImplementedError: I{algorithm} is not supported
+    """
+
+    hashes = {}
+    try:
+        import hashlib
+        hashes[dns.name.from_text('hmac-sha224')] = hashlib.sha224
+        hashes[dns.name.from_text('hmac-sha256')] = hashlib.sha256
+        hashes[dns.name.from_text('hmac-sha384')] = hashlib.sha384
+        hashes[dns.name.from_text('hmac-sha512')] = hashlib.sha512
+        hashes[dns.name.from_text('hmac-sha1')] = hashlib.sha1
+        hashes[dns.name.from_text('HMAC-MD5.SIG-ALG.REG.INT')] = hashlib.md5
+
+        import sys
+        if sys.hexversion < 0x02050000:
+            # hashlib doesn't conform to PEP 247: API for
+            # Cryptographic Hash Functions, which hmac before python
+            # 2.5 requires, so add the necessary items.
+            class HashlibWrapper:
+                def __init__(self, basehash):
+                    self.basehash = basehash
+                    self.digest_size = self.basehash().digest_size
+
+                def new(self, *args, **kwargs):
+                    return self.basehash(*args, **kwargs)
+
+            for name in hashes:
+                hashes[name] = HashlibWrapper(hashes[name])
+
+    except ImportError:
+        import md5, sha
+        hashes[dns.name.from_text('HMAC-MD5.SIG-ALG.REG.INT')] =  md5.md5
+        hashes[dns.name.from_text('hmac-sha1')] = sha.sha
+
+    if isinstance(algorithm, (str, unicode)):
+        algorithm = dns.name.from_text(algorithm)
+
+    if algorithm in hashes:
+        return (algorithm.to_digestable(), hashes[algorithm])
+
+    raise NotImplementedError("TSIG algorithm " + str(algorithm) +
+                              " is not supported")