Quick hack to demonstrate ROA maxLength expansion

svn path=/scripts/expand-roa-prefixes.py; revision=3800

1 files changed, 57 insertions, 0 deletions

diff --git a/scripts/expand-roa-prefixes.py b/scripts/expand-roa-prefixes.py
new file mode 100644
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+++ b/scripts/expand-roa-prefixes.py
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+"""
+I got tired of trying to explain in English how the maxLength macro
+hack works in ROAs, so this is an attempt to explain it as code.
+
+Given one or more ROA prefix sets on the command line, this script
+prints out the expansion as a list of prefixes.
+
+$Id$
+
+Copyright (C) 2011  Internet Systems Consortium ("ISC")
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.
+"""
+
+import sys, rpki.resource_set
+
+argv = sys.argv[1:] if len(sys.argv) > 1 else ["18.0.0.0/8-24"]
+prefix_sets = []
+
+for arg in argv:
+  if ":" in arg:
+    prefix_sets.extend(rpki.resource_set.roa_prefix_set_ipv6(arg))
+  else:
+    prefix_sets.extend(rpki.resource_set.roa_prefix_set_ipv4(arg))
+
+for prefix_set in prefix_sets:
+  sys.stdout.write("%s expands to:\n" % prefix_set)
+
+  prefix_type = prefix_set.range_type.datum_type
+  prefix_min = prefix_set.prefix
+  prefix_max = prefix_set.prefix + (1L << (prefix_type.bits - prefix_set.prefixlen))
+
+  for prefixlen in xrange(prefix_set.prefixlen, prefix_set.max_prefixlen + 1):
+
+    step = (1L << (prefix_type.bits - prefixlen))
+    mask = step - 1
+
+    for addr in xrange(prefix_min, prefix_max, step):
+
+      addr = prefix_type(addr)
+
+      if (addr & mask) != 0:
+        raise RuntimeError, "%s is not a /%d prefix" % (addr, prefixlen)
+
+      sys.stdout.write("  %s/%d\n" % (addr, prefixlen))
+
+  sys.stdout.write("\n")