Add a script for generating ipv6 addrs from pkey

scripts/wg-peer-to-ipv6

@@ -0,0 +1,52 @@
+#! /usr/bin/env python3
+import argparse
+import sys
+import logging
+import ipaddress
+import hashlib
+import base64
+
+logger = logging.getLogger(__name__)
+
+
+def main() -> int:
+    # Handle program arguments
+    ap = argparse.ArgumentParser(
+        prog="wg-peer-to-ipv6",
+        description="Deterministically generate IPv6 addresses from WireGuard public keys",
+    )
+    ap.add_argument("prefix", help="IPv6 prefix", type=ipaddress.IPv6Network)
+    ap.add_argument("public_key", help="WireGuard public key")
+    ap.add_argument(
+        "-v", "--verbose", help="Enable verbose logging", action="store_true"
+    )
+    args = ap.parse_args()
+
+    # Configure logging
+    logging.basicConfig(
+        level=logging.DEBUG if args.verbose else logging.INFO,
+        format="%(levelname)s:	%(message)s",
+    )
+    
+    # Decode the public key
+    public_key = base64.b64decode(args.public_key)
+    
+    # Hash the public key
+    hash = hashlib.sha256(public_key).digest()
+    
+    # Figure out how many bits we have for the host part
+    host_bits = args.prefix.max_prefixlen - args.prefix.prefixlen
+    
+    # Take that many bits from the hash
+    host = int.from_bytes(hash, "big") >> (256 - host_bits)
+    
+    # Create the IPv6 address
+    ipv6 = args.prefix.network_address + host
+    
+    print(ipv6)
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())