Add addrecord utility

diff --git a/addrecord b/addrecord
new file mode 100644 (file)
index 0000000..fa4c840
--- /dev/null
+++ b/addrecord
@@ -0,0 +1,109 @@
+#!/usr/bin/python3
+#
+# ssh-based server to allow hosts to update their own TLS-related RRs
+# intended to be used like
+#   command="/srv/tls/bin/addrecord hepworth.siccegge.de" ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOIlLx3R+Q5LgBZbJ6USuzam/uAEQITl6vzOn/ylk4fq christoph@mitoraj
+
+import os
+import sys
+import re
+import datetime
+import fcntl
+
+import yaml
+
+class Addrecord:
+    def __init__(self, host):
+        self._host = host
+        self._ports = {'www': [443],
+                       'smtp': [25, 587, 465],
+                       'imap': [993, 143],
+                       'pop': [110, 995],
+                       'xmpp': [5222, 5269],
+                      }
+        self._tlsa_re = re.compile('TLSA 3 1 1 [0-9a-f]{64}')
+        self._acme_re = re.compile(r'[a-zA-Z0-9_-]{43}')
+        with open('inventory.yaml') as inv:
+            self._inventory = yaml.load(inv)
+
+
+    def tlsa(self):
+        host = input("Hostname: ")
+        service = input("Service: ")
+        value = input("Value: ")
+        if host not in self._inventory[self._host][service]:
+            sys.stderr.write("Not authorized to update entries for service '%s' on '%s'\n"
+                              % (service, host))
+            return 1
+
+        if re.fullmatch(self._tlsa_re, value) is None:
+            sys.stderr.write("Not a valid TLSA record: '%s'\n" % value)
+            return 2
+
+        records = []
+        for port in self._ports[service]:
+            records.append("{0:<35s}\t{1}\n".format("_%d._tcp.%s" % (port, host),
+                                                    value))
+        self._update_records('tlsa', records)
+        print("OK")
+        return 0
+
+
+    def acme(self):
+        host = input("Hostname: ")
+        value = input("Value: ")
+        allowed_hosts = set()
+        for value in self._inventory[self._host].values():
+            allowed_hosts = allowed_hosts.union(value)
+
+        if host not in allowed_hosts:
+            sys.stderr.write("Not authorized to update entries for host '%s'\n" % host)
+            return 1
+
+        if re.fullmatch(self._acme_re, value) is None:
+            sys.stderr.write("Not a valid ACME challenge record: '%s'\n" % value)
+            return 2
+
+        records = [ "{0:<35s}\t{1}\n".format("_acme-challenge.%s" % host, value) ]
+        self._update_records('acme', records)
+        print("OK")
+        return 0
+
+
+    def _update_records(self, sort, records):
+        to_remove = [ i.split()[0] for i in records ]
+
+        with open('%s/%s.m4' % (sort, self._host), 'r') as oldzone:
+            fcntl.flock(oldzone, fcntl.LOCK_EX)
+            lines = oldzone.readlines()
+            lines = [ line for line in lines if line == '\n' or line.split()[0] not in to_remove ]
+
+            lines.append('\n')
+            lines.append("; Last updated %s by %s\n" % (datetime.datetime.utcnow().isoformat(),
+                                                        self._host))
+            lines = lines + records
+
+            with open('%s/%s.m4.new' % (sort, self._host), 'w') as newzone:
+                newtext = ''.join(lines)
+                newtext = re.sub(r'\n[\n]+', '\n\n', newtext)
+                newtext = re.sub(r'\n;.*\n\n;', '\n;', newtext)
+                newzone.write(newtext)
+
+            os.rename('%s/%s.m4.new' % (sort, self._host),
+                      '%s/%s.m4' % (sort, self._host))
+            fcntl.flock(oldzone, fcntl.LOCK_UN)
+
+
+def main():
+    command = os.environ['SSH_ORIGINAL_COMMAND']
+    host = sys.argv[1]
+    addrecord = Addrecord(host)
+
+    if command == 'acme':
+        return addrecord.acme()
+    elif command == 'tlsa':
+        return addrecord.tlsa()
+
+
+if __name__ == '__main__':
+    sys.exit(main())