#!/usr/bin/env python
# Read a tinydns data file, and output BIND-style zone files and config.
# Adam Sampson <ats@offog.org>
#
# The input language this understands is documented on the djbdns web site:
#   http://cr.yp.to/djbdns/tinydns-data.html
# It only generates zone files for domains that it's seen an SOA entry for, so
# if you're not getting any output make sure you've got the appropriate "."
# lines for your domains in the input file.
#
# I've used the output from this script successfully with PowerDNS and nsd, but
# the zone files should work with most nameservers.

import sys, os, os.path

def die(*s):
	sys.stderr.write(" ".join(map(str, s)) + "\n")
	sys.exit(1)

def make_inaddr(ip):
	bits = ip.split(".")
	if len(bits) != 4:
		die("Bad IPv4 address:", ip)
	bits.reverse()
	return ".".join(bits) + ".in-addr.arpa"

def add_dot(s):
	if s != "" and s[-1] != ".":
		return s + "."
	else:
		return s

def unescape_tinydns(s):
	out = ""
	i = 0
	while i < len(s):
		if s[i] == '\\':
			out += chr(int(s[i + 1:i + 4], 8))
			i += 3
		else:
			out += s[i]
		i += 1
	return out

def escape_zone(s):
	return s.replace('"', '\"')

def main(args):
	if len(args) != 2:
		die("Usage: tinydns-to-zones DATA-FILE OUTPUT-DIR")
	(input_fn, output_dir) = args

	domains = {}
	records = []

	f = open(input_fn, "r")
	default_ser = str(int(os.fstat(f.fileno()).st_mtime))
	for l in f.xreadlines():
		l = l.strip()
		if l == "":
			continue
		c = l[0]
		if c == "#" or c == "-":
			continue
		a = l[1:].split(":")

		ttl = ""
		timestamp = ""
		lo = ""
		def parse(n):
			global ttl, timestamp, lo
			if len(a) < 2:
				die("Too few args in line:", l)
			while len(a) < n:
				a.append("")
			(ttl, timestamp, lo) = (a[n:] + ["", "", ""])[:3]
			if timestamp != "" or lo != "":
				die("timestamp/lo not yet supported in line:", l)
			return a[:n]

		def add_record(fqdn, type, data, def_ttl = "86400"):
			global ttl
			if ttl == "":
				ttl = def_ttl
			records.append([add_dot(fqdn), "IN", ttl, type, data])

		def add_soa(fqdn, mname, rname, ser = default_ser, ref = "", ret = "", exp = "", min = ""):
			if ser == "":
				ser = default_ser
			if ref == "":
				ref = "16384"
			if ret == "":
				ret = "2048"
			if exp == "":
				exp = "1048576"
			if min == "":
				min = "2560"
			global ttl
			if ttl == "":
				ttl = "2560"
			domains[fqdn] = [add_dot(fqdn), "IN", ttl, "SOA", "%s %s %s %s %s %s %s" % (add_dot(mname), add_dot(rname), ser, ref, ret, exp, min)]

		if c == "." or c == "&":
			(fqdn, ip, x) = parse(3)
			if "." in x:
				ns_name = x
			else:
				ns_name = x + ".ns." + fqdn
			if c == ".":
				add_soa(fqdn, ns_name, "hostmaster." + fqdn)
			add_record(fqdn, "NS", add_dot(ns_name), "2560")
			if ip != "":
				add_record(ns_name, "A", ip)
		elif c == "=" or c == "+":
			(fqdn, ip) = parse(2)
			add_record(fqdn, "A", ip)
			if c == "=":
				add_record(make_inaddr(ip), "PTR", add_dot(fqdn))
		elif c == "@":
			(fqdn, ip, x, dist) = parse(4)
			if "." in x:
				mx_name = x
			else:
				mx_name = x + ".mx." + fqdn
			if dist == "":
				dist = "0"
			add_record(fqdn, "MX", dist + " " + add_dot(mx_name))
			if ip != "": # not in spec, but assumed...
				add_record(mx_name, "A", ip)
		elif c == "'":
			(fqdn, s) = parse(2)
			s = escape_zone(unescape_tinydns(s))
			add_record(fqdn, "TXT", '"' + s + '"')
		elif c == "^":
			(fqdn, p) = parse(2)
			add_record(fqdn, "PTR", add_dot(p))
		elif c == "C":
			(fqdn, p) = parse(2)
			add_record(fqdn, "CNAME", add_dot(p))
		elif c == "Z":
			a = parse(8)
			add_soa(*a)
		elif c == ":":
			(fqdn, n, rdata) = parse(3)
			if int(n) != 16:
				die("Generic record not supported in line:", l)
			# This is the specific case of : being used to generate
			# a TXT record, to work around tinydns splitting ' data
			# into multiple items. This is widely used for
			# DomainKeys.
			rdata = unescape_tinydns(rdata)
			data = ""
			while rdata != "":
				bytes = ord(rdata[0])
				data += rdata[1:bytes + 1]
				rdata = rdata[bytes + 1:]
			add_record(fqdn, "TXT", '"' + escape_zone(data) + '"')
	f.close()

	def write_record(f, r):
		f.write("\t".join(r) + "\n")

	output_dir = os.path.abspath(output_dir)
	try:
		os.makedirs(output_dir + "/zones")
	except OSError:
		pass
	cf = open(output_dir + "/named.conf", "w")
	nf = open(output_dir + "/nsd.zones", "w")
	for dom in domains.keys():
		soa = domains[dom]
		fn = "zones/" + dom + ".pri"
		# Use fully-qualified path in the config file, since PowerDNS
		# will complain otherwise...
		full_fn = output_dir + "/" + fn
		cf.write('zone "' + dom + '" in {\n    type master;\n    file "' + full_fn + '";\n};\n')
		nf.write('zone\t%s\t%s\n' % (dom, fn))
		f = open(full_fn, "w")
		write_record(f, soa)
		for r in records:
			if r[0].endswith(soa[0]):
				write_record(f, r)
		f.close()
	cf.close()
	nf.close()
		
	cf.close()

if __name__ == "__main__":
	main(sys.argv[1:])