Update merge.py

utils/merge.py

@@ -3,10 +3,26 @@ import argparse
 import netaddr
 
 
-if __name__ == '__main__':
+def iter_networks(source):
+    for line_number, raw_value in enumerate(source, start=1):
+        value = raw_value.strip()
+        if not value:
+            continue
+
+        try:
+            yield netaddr.IPNetwork(value)
+        except netaddr.AddrFormatError as exc:
+            raise SystemExit(f'Invalid IP or CIDR on line {line_number}: {value!r}') from exc
+
+
+def main():
     parser = argparse.ArgumentParser(description='Merge IP addresses into the smallest possible list of CIDRs.')
     parser.add_argument('--source', nargs='?', type=argparse.FileType('r'), required=True, help='Source file path')
     args = parser.parse_args()
 
-    for addr in netaddr.cidr_merge(args.source.readlines()):
+    for addr in netaddr.cidr_merge(iter_networks(args.source)):
         print(addr)
+
+
+if __name__ == '__main__':
+    raise SystemExit(main())