Data commit

Task/Canonicalize-CIDR/Python/canonicalize-cidr-1.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+# canonicalize a CIDR block specification:
+# make sure none of the host bits are set
+
+import sys
+from socket import inet_aton, inet_ntoa
+from struct import pack, unpack
+
+args = sys.argv[1:]
+if len(args) == 0:
+    args = sys.stdin.readlines()
+
+for cidr in args:
+   # IP in dotted-decimal / bits in network part
+   dotted, size_str = cidr.split('/')
+   size = int(size_str)
+
+   numeric = unpack('!I', inet_aton(dotted))[0]  # IP as an integer
+   binary = f'{numeric:#034b}'                   # then as a padded binary string
+   prefix = binary[:size + 2]                    # just the network part
+                                                 #   (34 and +2 are to account
+                                                 #    for leading '0b')
+
+   canon_binary = prefix + '0' * (32 - size)     # replace host part with all zeroes
+   canon_numeric = int(canon_binary, 2)          # convert back to integer
+   canon_dotted = inet_ntoa(pack('!I',
+                            (canon_numeric)))    # and then to dotted-decimal
+   print(f'{canon_dotted}/{size}')               # output result

Task/Canonicalize-CIDR/Python/canonicalize-cidr-2.py

@@ -0,0 +1,38 @@
+"""Canonicalize CIDR"""
+DIGITS = (24, 16, 8, 0)
+
+
+def dotted_to_int(dotted: str) -> int:
+    digits = [int(digit) for digit in dotted.split(".")]
+    return sum(a << b for a, b in zip(digits, DIGITS))
+
+
+def int_to_dotted(ip: int) -> str:
+    digits = [(ip & (255 << d)) >> d for d in DIGITS]
+    return ".".join(str(d) for d in digits)
+
+
+def network_mask(number_of_bits: int) -> int:
+    return ((1 << number_of_bits) - 1) << (32 - number_of_bits)
+
+
+def canonicalize(ip: str) -> str:
+    dotted, network_bits = ip.split("/")
+    i = dotted_to_int(dotted)
+    mask = network_mask(int(network_bits))
+    return int_to_dotted(i & mask) + "/" + network_bits
+
+
+TEST_CASES = [
+    ("36.18.154.103/12", "36.16.0.0/12"),
+    ("62.62.197.11/29", "62.62.197.8/29"),
+    ("67.137.119.181/4", "64.0.0.0/4"),
+    ("161.214.74.21/24", "161.214.74.0/24"),
+    ("184.232.176.184/18", "184.232.128.0/18"),
+]
+
+if __name__ == "__main__":
+    for ip, expect in TEST_CASES:
+        rv = canonicalize(ip)
+        print(f"{ip:<18} -> {rv}")
+        assert rv == expect

Task/Canonicalize-CIDR/Python/canonicalize-cidr-3.py

@@ -0,0 +1,18 @@
+import ipaddress
+
+def canonicalize(address: str) -> str:
+    return str(ipaddress.ip_network(address, strict=False))
+
+TEST_CASES = [
+    ("36.18.154.103/12", "36.16.0.0/12"),
+    ("62.62.197.11/29", "62.62.197.8/29"),
+    ("67.137.119.181/4", "64.0.0.0/4"),
+    ("161.214.74.21/24", "161.214.74.0/24"),
+    ("184.232.176.184/18", "184.232.128.0/18"),
+]
+
+if __name__ == "__main__":
+    for ip, expect in TEST_CASES:
+        rv = canonicalize(ip)
+        print(f"{ip:<18} -> {rv}")
+        assert rv == expect, expect