*/*: reorganize for easy testing using setuptools or tox.

[djbdns-logparse.git] / djbdns / common.py

diff --git a/djbdns/common.py b/djbdns/common.py
new file mode 100644 (file)
index 0000000..6ef4e1c
--- /dev/null
+++ b/djbdns/common.py
@@ -0,0 +1,72 @@
+from struct import pack
+
+# A pattern to match the timestamp format that the tai64nlocal program
+# produces. It appears in both dnscache and tinydns lines, after
+# they've been piped through tai64nlocal, of course.
+timestamp_pat = r'[\d-]+ [\d:\.]+'
+
+# A dictionary mapping query type identifiers, in decimal, to their
+# friendly names for tinydns. Reference:
+#
+#   https://en.wikipedia.org/wiki/List_of_DNS_record_types
+#
+# Note that mapping here is non-exhaustive, and that tinydns will
+# log responses for record types that it does not know about.
+query_type = {
+      1: "a",
+      2: "ns",
+      5: "cname",
+      6: "soa",
+     12: "ptr",
+     13: "hinfo",
+     15: "mx",
+     16: "txt",
+     17: "rp",
+     24: "sig",
+     25: "key",
+     28: "aaaa",
+     33: "srv",
+     35: "naptr",
+     38: "a6",
+     48: "dnskey",
+     52: "tlsa",
+     65: "https",
+    252: "axfr",
+    255: "any",
+    257: "caa"
+}
+
+def convert_ip(ip : str) -> str:
+    r"""
+    Convert a hex string representing an IP address to
+    human-readable form.
+
+    Parameters
+    ----------
+
+    ip : str
+        The hexadecimal representation of either an IPv4 or an IPv6
+        address.
+
+    Returns
+    -------
+
+    The usual decimal dotted-quad representation is returned for an
+    IPv4 address. IPv6 addresses are returned almost as-is, but with
+    colons inserted in the appropriate places, between every four
+    characters.
+
+    Examples
+    --------
+
+        >>> convert_ip("7f000001")
+        '127.0.0.1'
+        >>> convert_ip("00000000000000000000ffff7f000001")
+        '0000:0000:0000:0000:0000:ffff:7f00:0001'
+    """
+    if len(ip) == 8:
+        # IPv4, eg. "7f000001" -> "7f 00 00 01" -> "127.0.0.1"
+        return ".".join(map(str, pack(">L", int(ip, 16))))
+    elif len(ip) == 32:
+        # IPv6 is actually simpler -- it's just a string-slicing operation.
+        return ":".join([ip[(4*i) : (4*i+4)] for i in range(8)])