Ensure the title of the 'Issuer' block is no more than 50 characters

- chop off the `https://` to give us a little more room
- use a sha1 hash if the title is still too big

src/tests/test_stashcache.py

@@ -1,6 +1,7 @@
 from configparser import ConfigParser
 import copy
 import flask
+import hashlib
 import pytest
 import re
 from pytest_mock import MockerFixture
@@ -112,15 +113,17 @@ def test_scitokens_issuer_character_limit(self, client: flask.Flask):
         cp = ConfigParser()
         cp.read_string(origin_scitokens_conf, "origin_scitokens.conf")
 
+        hasher = hashlib.sha1()
+        hasher.update(b"test.wisc.edu/long-name-that-is-over-50-characters-even-if-you-strip-off-https")
+        hashed_title = hasher.hexdigest()
         try:
             assert "Global" in cp, "Missing Global section"
-            assert "Issuer https://test.wisc.edu" in cp, \
+            assert "Issuer test.wisc.edu" in cp, \
                 "Issuer with reasonable length missing"
             assert "Issuer issuer-thats-50-characters-long-if-you.chop" in cp, \
                 "Issuer that just barely fits if you chop off the scheme missing"
-            assert (cp["Issuer issuer-thats-50-characters-long-if-you.chop"]["issuer"] ==
-                    "https://issuer-thats-50-characters-long-if-you.chop"), \
-                "Unexpected issuer in a section we modified"
+            assert f"Issuer {hashed_title}" in cp, \
+                "Issuer that's needed to be hashed missing"
             assert not re.search(r"^\[[^]]{51}", origin_scitokens_conf, re.MULTILINE), \
                 "Section over 50 chars long found"
             # ^^ easier to regexp this

src/webapp/data_federation.py

@@ -1,3 +1,4 @@
+import hashlib
 import urllib
 import urllib.parse
 from collections import OrderedDict
@@ -76,6 +77,8 @@ def get_authfile_id(self):
 
 class SciTokenAuth(AuthMethod):
     used_in_scitokens_conf = True
+    ISSUER_TITLE_MAX_LENGTH = 43  # 50 - the length of 'Issuer '
+                                  # xrootd/xrootd#2074
 
     def __init__(self, issuer: str, base_path: str, restricted_path: Optional[str], map_subject: bool):
         self.issuer = issuer
@@ -90,7 +93,17 @@ def __str__(self):
     def get_scitokens_conf_block(self, service_name: str):
         if service_name not in [XROOTD_CACHE_SERVER, XROOTD_ORIGIN_SERVER]:
             raise ValueError(f"service_name must be '{XROOTD_CACHE_SERVER}' or '{XROOTD_ORIGIN_SERVER}'")
-        block = (f"[Issuer {self.issuer}]\n"
+
+        issuer_title = self.issuer
+        if issuer_title.startswith("https://"):
+            issuer_title = issuer_title[8:]
+        # title is too long; replace it with a hash
+        if len(issuer_title) > self.ISSUER_TITLE_MAX_LENGTH:
+            hasher = hashlib.sha1()  # sha1 hex digest is 40 chars
+            hasher.update(issuer_title.encode("utf-8", errors="ignore"))
+            issuer_title = hasher.hexdigest()
+
+        block = (f"[Issuer {issuer_title}]\n"
                  f"issuer = {self.issuer}\n"
                  f"base_path = {self.base_path}\n")
         if self.restricted_path: