#!/usr/bin/python3

# Generate DNS RR type constants for resolv header files.

# Copyright (C) 2016-2018 Free Software Foundation, Inc.

# This file is part of the GNU C Library.

#

# The GNU C Library is free software; you can redistribute it and/or

# modify it under the terms of the GNU Lesser General Public

# License as published by the Free Software Foundation; either

# version 2.1 of the License, or (at your option) any later version.

#

# The GNU C Library is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# Lesser General Public License for more details.

#

# You should have received a copy of the GNU Lesser General Public

# License along with the GNU C Library; if not, see

# <http://www.gnu.org/licenses/>.

"""Generate DNS RR type constants for resolv header files.

resolv/arpa/nameser.h and resolv/arpa/nameser_compat.h contain lists

of RR type constants.  This script downloads the current definitions

from the IANA DNS Parameters protocol registry and translates it into

the two different lists.

Two lists are written to standard output.  The first one contains enum

constants for resolv/arpa/nameser.h.  The second one lists the

preprocessor macros for resolv/arpa/nameser_compat.h.

"""

# URL of the IANA registry.

source = "http://www.iana.org/assignments/dns-parameters/dns-parameters-4.csv"

import collections

import csv

import io

import urllib.request

Type = collections.namedtuple("Type", "name number comment")

def get_types(source):

    for row in csv.reader(io.TextIOWrapper(urllib.request.urlopen(source))):

        if row[0] in ('TYPE', 'Unassigned', 'Private use', 'Reserved'):

            continue

        name, number, comment = row[:3]

        if name == '*':

            name = 'ANY'

            comment = 'request for all cached records'

        number = int(number)

        yield Type(name, number, comment)

types = list(get_types(source))

print("// enum constants for resolv/arpa/nameser.h")

print()

for typ in types:

    name = typ.name.replace("-", "_").lower()

    print("    ns_t_{0} = {1.number},".format(name, typ))

print()

print("// macro aliases resolv/arpa/nameser_compat.h")

print()

for typ in types:

    name = typ.name.replace("-", "_")

    print("#define T_{0} ns_t_{1}".format(name.upper(), name.lower()))

print()