1 files changed, 130 insertions, 0 deletions
diff --git a/rzc.py b/rzc.py
new file mode 100755
index 0000000..da1107d
--- /dev/null
+++ b/rzc.py
@@ -0,0 +1,130 @@
+#!/usr/bin/env python3
+
+"""
+Reverse Zone Compiler (document this...)
+"""
+
+from argparse import ArgumentParser, FileType, ArgumentDefaultsHelpFormatter
+from datetime import datetime, UTC
+from pathlib import Path
+from os import getenv
+from sys import argv
+
+from dns.rdatatype import A, AAAA, SOA, NS, PTR, CNAME
+from dns.rdataclass import IN
+from dns.node import NodeKind
+
+import dns.rdtypes.ANY.CNAME
+import dns.rdtypes.ANY.SOA
+import dns.rdtypes.ANY.PTR
+import dns.tsigkeyring
+import dns.reversename
+import dns.rdataclass
+import dns.rdatatype
+import dns.rdataset
+import dns.query
+import dns.rdata
+import dns.name
+import dns.zone
+
+import toml
+
+class Main:
+
+    def __init__(self):
+        self.jane = Path(argv[0]).resolve()
+
+        ap = ArgumentParser(formatter_class = ArgumentDefaultsHelpFormatter)
+        ap.add_argument("-c", "--config", type = FileType("r"),
+                        default = getenv("RZC_CONFIG", f"{self.jane.stem}.toml"),
+                        help = "TOML configuration file")
+        args = ap.parse_args()
+
+        self.cfg = toml.load(args.config, JinjaDict)
+        self.now = datetime.now(UTC)
+
+        self.output_dir = Path(self.cfg.output.directory)
+        self.cache_dir  = Path(self.cfg.input.cache)
+
+        self.fetch_input_zones()
+        self.initialize_output_zones()
+        self.populate_output_zones()
+        self.write_output_zones()
+
+    def fetch_input_zones(self):
+        self.cache_dir.mkdir(parents = True, exist_ok = True)
+        self.forward = []
+
+        for iz in self.cfg.input.zone:
+            origin = dns.name.from_text(iz.name)
+            path = self.cache_dir / origin.to_text(omit_final_dot = True)
+            try:
+                with path.open("r") as f:
+                    fz = dns.zone.from_file(f, origin = origin, relativize = False)
+            except:
+                fz = dns.zone.Zone(origin = origin, relativize = False)
+            try:
+                keyring = dns.tsigkeyring.from_text(iz.tsig) if iz.tsig else None
+                query, serial = dns.xfr.make_query(txn_manager = fz, keyring = keyring)
+                dns.query.inbound_xfr(where = iz.server, txn_manager = fz, query = query)
+            except Exception as e:
+                print(f"Unable to XFR {iz.name}: {e}")
+                continue
+            with path.open("w") as f:
+                fz.to_file(f, sorted = True, relativize = False)
+            print(f"Updated {iz.name}")
+            self.forward.append(fz)
+
+    def initialize_output_zones(self):
+        self.reverse = []
+
+        for oz in self.cfg.output.zones:
+            rz = dns.zone.Zone(dns.name.from_text(oz), rdclass = IN, relativize = False)
+            apex = rz.find_node(rz.origin, create = True)
+            apex.replace_rdataset(
+                dns.rdataset.from_rdata(
+                    self.cfg.output.ttl,
+                    dns.rdtypes.ANY.SOA.SOA(
+                        IN, SOA,
+                        dns.name.from_text(self.cfg.output.soa.mname),
+                        dns.name.from_text(self.cfg.output.soa.rname),
+                        int(self.now.timestamp()),
+                        self.cfg.output.soa.refresh, self.cfg.output.soa.retry,
+                        self.cfg.output.soa.expire, self.cfg.output.soa.minimum)))
+            apex.replace_rdataset(
+                dns.rdataset.from_text_list(
+                    IN, NS, self.cfg.output.ttl, self.cfg.output.ns,
+                    relativize = False, origin = dns.name.root))
+            rz.check_origin()
+            self.reverse.append(rz)
+
+    def populate_output_zones(self):
+        for fz in self.forward:
+            for qtype in (A, AAAA):
+                for name, ttl, addr in fz.iterate_rdatas(qtype):
+                    name = name.derelativize(fz.origin)
+                    rname = dns.reversename.from_address(addr.to_text())
+                    rdata = dns.rdtypes.ANY.PTR.PTR(IN, PTR, name)
+                    for rz in self.reverse:
+                        if rname.is_subdomain(rz.origin):
+                            rz.find_rdataset(rname, PTR, create = True).add(rdata, ttl)
+                            break
+
+    def write_output_zones(self):
+        self.output_dir.mkdir(parents = True, exist_ok = True)
+        for rz in self.reverse:
+            path = self.output_dir / rz.origin.to_text(omit_final_dot = True)
+            with path.open("w") as f:
+                f.write(f";; Automatically generated {self.now} by {self.jane}.  Do not edit.\n\n")
+                rz.to_file(f, sorted = True, relativize = False)
+            print(f"Wrote {path}")
+
+class JinjaDict(dict):
+    def __getattr__(self, name):
+        try:
+            return self[name]
+        except KeyError:
+            return None
+
+if __name__ == "__main__":
+    Main()