Improvements

server/cf-radar.js

@@ -188,8 +188,9 @@ export const normalizePrefixOrigins = (result) => {
 };
 
 const GEO_TOP = 50;              // countries in the response
-const GEO_PREFIX_CAP = 20000;    // bound on prefixes considered per request
-const GEO_LOOKUP_BUDGET = 100000; // hard cap on MaxMind lookups per request (~0.3 s)
+// Hard cap on MaxMind lookups per request (~0.3 s). Every uncovered prefix
+// costs at least one, so this bounds the walk however many Radar returns.
+const GEO_LOOKUP_BUDGET = 100000;
 
 // Share of the ASN's announced IPv4 addresses per geolocated country, largest
 // first. v4-only and address-weighted (a /16 counts 256× a /24); prefixes
@@ -200,16 +201,14 @@ const GEO_LOOKUP_BUDGET = 100000; // hard cap on MaxMind lookups per request (~0
 // `lookupRange(ip) → { country, prefixLength } | null` is injected so tests
 // need no MaxMind database; null = no answer (no database, or the lookup
 // failed), unlike an address MaxMind places nowhere ({ country: null }).
-// Resolves { shares, complete }: more IPv4 prefixes than the cap, a null
-// answer or the budget ending the walk gives { shares: [], complete: false } — shares over part of the space
+// Resolves { shares, complete }: a null answer or the budget ending the walk
+// gives { shares: [], complete: false } — shares over part of the space
 // would read as the whole distribution — and the caller must not cache it.
 // Exported for tests.
 export const buildCountryShares = (prefixes, lookupRange) => {
-    const v4 = (prefixes || [])
+    const blocks = (prefixes || [])
         .map((row) => parseCidr(row?.prefix))
-        .filter((cidr) => cidr?.family === 4);
-    if (v4.length > GEO_PREFIX_CAP) return { shares: [], complete: false };
-    const blocks = v4
+        .filter((cidr) => cidr?.family === 4)
         .map((cidr) => ({ start: cidr.network, size: 2n ** BigInt(32 - cidr.prefix) }))
         .sort((a, b) => (a.start === b.start ? Number(b.size - a.size) : (a.start < b.start ? -1 : 1)));
 

tests/cf-radar.test.js

@@ -432,15 +432,16 @@ describe('buildCountryShares', () => {
         assert.deepEqual(result, { shares: [], complete: false });
     });
 
-    it('more IPv4 prefixes than the cap is incomplete, with no lookups', () => {
-        // 20001 distinct /24s under 10.0.0.0/8.
-        const many = Array.from({ length: 20001 }, (_, i) => ({ prefix: `10.${i >> 8}.${i & 255}.0/24` }));
+    it('bounds the walk by lookups, not by how many prefixes Radar returns', () => {
+        // 30000 /24s under 10.0.0.0/8 (one per 256 addresses).
+        const specifics = Array.from({ length: 30000 }, (_, i) => ({ prefix: `10.${i >> 8}.${i & 255}.0/24` }));
+        // Under a covering /8 they are skipped: one lookup, complete.
         let calls = 0;
-        const result = buildCountryShares(many, () => { calls++; return { country: 'US', prefixLength: 24 }; });
-        assert.deepEqual(result, { shares: [], complete: false });
-        assert.equal(calls, 0);
-        // At the cap the walk still runs.
-        assert.equal(buildCountryShares(many.slice(0, 20000), () => ({ country: 'US', prefixLength: 24 })).complete, true);
+        const wide = () => { calls++; return { country: 'US', prefixLength: 8 }; };
+        assert.deepEqual(shares([{ prefix: '10.0.0.0/8' }, ...specifics], wide), [{ country: 'US', share: 1 }]);
+        assert.equal(calls, 1);
+        // Uncovered, each costs a lookup; well within the budget, complete.
+        assert.equal(buildCountryShares(specifics, () => ({ country: 'US', prefixLength: 24 })).complete, true);
     });
 
     it('a lookup without an answer (no database, failed lookup) is incomplete, not "no countries"', () => {