Drop a filter that matched nothing, keep the 79 ports it hid, and exit on a value the registers should not hold

data-import/protocol.py

@@ -3,12 +3,14 @@
 
     data-import/protocol.py [--source URL_OR_FILE] [--cache DIR] [--out FILE]
 
-A number the registry leaves unassigned, reserves or marks deprecated does not ship.
-Where it names no protocol beside the keyword, the keyword is the name.
+A row needs a number and a keyword, which drops the seven numbers assigned to a class of
+protocols rather than to one; a keyword the registry reserves or marks deprecated goes
+too. Where the registry names no protocol beside the keyword, the keyword is the name.
 """
 import argparse
 import csv
 import io
+import sys
 from pathlib import Path
 
 import source
@@ -18,15 +20,28 @@ SOURCE = "https://www.iana.org/assignments/protocol-numbers/protocol-numbers-1.c
 OUT = Path(__file__).resolve().parent.parent / "data" / "misc" / "protocol.tsv"
 CACHE = Path(__file__).resolve().parent / "cache"
 COLUMNS = ["keyword", "name", "number"]
-SKIP = ("Unassigned", "Reserved", "deprecated")
+SKIP = ("Reserved", "deprecated")
 
 
 def rows(text):
     for r in csv.DictReader(io.StringIO(text)):
-        number, keyword = r["Decimal"].strip(), r["Keyword"].strip()
+        number, keyword = (r["Decimal"] or "").strip(), (r["Keyword"] or "").strip()
         if not number.isdigit() or not keyword or any(s in keyword for s in SKIP):
             continue
-        yield {"keyword": keyword, "name": " ".join(r["Protocol"].split()) or keyword, "number": number}
+        if not 0 <= int(number) <= 255:
+            sys.exit(f"{keyword}: protocol number {number} is outside 0-255")
+        yield {"keyword": keyword, "name": " ".join((r["Protocol"] or "").split()) or keyword, "number": number}
+
+
+def refuse_a_name_the_loader_would(table):
+    """A name spelling another row's keyword, or a second row's name, is a load error for every consumer."""
+    keywords, seen = {r["keyword"] for r in table}, {}
+    for r in table:
+        if r["name"] != r["keyword"] and r["name"] in keywords:
+            sys.exit(f"{r['keyword']}: name {r['name']!r} is another protocol's keyword")
+        if r["name"] in seen:
+            sys.exit(f"{r['keyword']}: name {r['name']!r} repeats {seen[r['name']]}'s")
+        seen[r["name"]] = r["keyword"]
 
 
 def main():
@@ -36,6 +51,7 @@ def main():
     p.add_argument("--out", default=str(OUT))
     a = p.parse_args()
     table = sorted(rows(source.fetch(a.source, a.cache, "protocol-numbers-1.csv").decode("utf-8")), key=lambda r: int(r["number"]))
+    refuse_a_name_the_loader_would(table)
     tsv.write(a.out, COLUMNS, table)