1 files changed, 104 insertions, 0 deletions
diff --git a/lib/dnspython/dns/opcode.py b/lib/dnspython/dns/opcode.py
new file mode 100644
index 0000000000..735d3a1f7d
--- /dev/null
+++ b/lib/dnspython/dns/opcode.py
@@ -0,0 +1,104 @@
+# 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 Opcodes."""
+
+import dns.exception
+
+QUERY = 0
+IQUERY = 1
+STATUS = 2
+NOTIFY = 4
+UPDATE = 5
+
+_by_text = {
+    'QUERY' : QUERY,
+    'IQUERY' : IQUERY,
+    'STATUS' : STATUS,
+    'NOTIFY' : NOTIFY,
+    'UPDATE' : UPDATE
+}
+
+# We construct the inverse mapping programmatically to ensure that we
+# cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
+# would cause the mapping not to be true inverse.
+
+_by_value = dict([(y, x) for x, y in _by_text.iteritems()])
+
+
+class UnknownOpcode(dns.exception.DNSException):
+    """Raised if an opcode is unknown."""
+    pass
+
+def from_text(text):
+    """Convert text into an opcode.
+
+    @param text: the textual opcode
+    @type text: string
+    @raises UnknownOpcode: the opcode is unknown
+    @rtype: int
+    """
+
+    if text.isdigit():
+        value = int(text)
+        if value >= 0 and value <= 15:
+            return value
+    value = _by_text.get(text.upper())
+    if value is None:
+        raise UnknownOpcode
+    return value
+
+def from_flags(flags):
+    """Extract an opcode from DNS message flags.
+
+    @param flags: int
+    @rtype: int
+    """
+
+    return (flags & 0x7800) >> 11
+
+def to_flags(value):
+    """Convert an opcode to a value suitable for ORing into DNS message
+    flags.
+    @rtype: int
+    """
+
+    return (value << 11) & 0x7800
+
+def to_text(value):
+    """Convert an opcode to text.
+
+    @param value: the opcdoe
+    @type value: int
+    @raises UnknownOpcode: the opcode is unknown
+    @rtype: string
+    """
+
+    text = _by_value.get(value)
+    if text is None:
+        text = str(value)
+    return text
+
+def is_update(flags):
+    """True if the opcode in flags is UPDATE.
+
+    @param flags: DNS flags
+    @type flags: int
+    @rtype: bool
+    """
+
+    if (from_flags(flags) == UPDATE):
+        return True
+    return False