From 63aba73d98a2b534d24501ec44a9457a5b30106b Mon Sep 17 00:00:00 2001
From: Local Dev <dev@localhost>
Date: Sun, 20 Sep 2026 18:35:09 +0200
Subject: [PATCH] feat(gateway): rewrite cross-name absolute links through
 /bns/
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theseus.x had a hardcoded href="https://sirius.x/" that worked in Theseus
(which resolves BCH names natively) but 404'd for ordinary browsers
served through the relay. Fixing it in every source file each time a
site adds a cross-name link is thankless; fix it once at the gateway.

New transformHtml() = injectBase() + rewriteBnsLinks(). The rewrite
matches href="https?://<label>.<tld>/..." and, when <tld> is a known
BCDN-only TLD, replaces the URL with /bns/<host>/... so the click stays
inside the relay origin.

Allowlisted TLDs: bch, x, p2p, deviant, bit, nav, test, coin, cash.
Intentionally EXCLUDED: st, com, gt, sc, de — those exist in ICANN and
rewriting them would hijack real web references (dl.silentmode.st is
the working case). The rewrite only fires on gateway-served HTML, so
the source sites remain clean when consumed at their native origin
by Theseus or Ariadne.

Verified: https://sirius.x/ on theseus.x home + plug-ins pages now
becomes /bns/sirius.x/; ordinary dl.silentmode.st links unchanged.
---
 src/gateway/public-gateway.mjs | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/gateway/public-gateway.mjs b/src/gateway/public-gateway.mjs
index f11192b..a78ab84 100644
--- a/src/gateway/public-gateway.mjs
+++ b/src/gateway/public-gateway.mjs
@@ -267,6 +267,32 @@ function injectBase(html, href) {
   if (/<head[^>]*>/i.test(html)) return html.replace(/<head[^>]*>/i, (m) => m + `<base href="${href}">`);
   return `<base href="${href}">` + html;
 }
+// TLDs the gateway will route through /bns/ when it sees them on a cross-name
+// absolute link inside served HTML. Restricted to TLDs that are BCDN-only or
+// deliberately BCDN-shadowed (never a live ICANN answer today) so we don't
+// mis-hijack an ordinary web reference. .st, .com, .gt, .sc are intentionally
+// EXCLUDED — they live in ICANN and rewriting them would break real links.
+const BNS_TLDS_REWRITABLE = new Set(["bch","x","p2p","deviant","bit","nav","test","coin","cash"]);
+// Rewrite <a href="https://<label>.<bcdn-tld>/..."> to <a href="/bns/<label>.<bcdn-tld>/...">
+// so an ordinary browser served through the relay follows the link back through
+// the relay instead of trying to resolve the BCDN name via DNS (which returns
+// NXDOMAIN). This is a NO-OP on the native origin (Theseus/Ariadne), because
+// the gateway never serves there — those clients see the original URLs.
+function rewriteBnsLinks(html) {
+  return html.replace(
+    /\bhref\s*=\s*"(https?:\/\/([a-z0-9-]+(?:\.[a-z0-9-]+)*\.([a-z0-9-]+))(\/[^"]*)?)"/gi,
+    (m, full, host, tld, path) => {
+      if (!BNS_TLDS_REWRITABLE.has(tld.toLowerCase())) return m;
+      return `href="/bns/${host.toLowerCase()}${path || "/"}"`;
+    }
+  );
+}
+// Apply both transforms (base first, then link rewrite) — order doesn't
+// matter because they touch disjoint constructs, but grouping them here
+// means every text/html response goes through the same path.
+function transformHtml(html, baseHref) {
+  return rewriteBnsLinks(injectBase(html, baseHref));
+}
 const nx = (h) => `<div style="font:16px system-ui;padding:2rem;color:#333"><h2>NXDOMAIN</h2><p><code>${h}</code> is not registered on the Bitcoin Cash chain.</p></div>`;
 
 // BNS `ip`-record fetch. The default `fetch` fails here for two reasons:
@@ -404,7 +430,7 @@ async function serve(res, name, reqPath, baseHref) {
       case "h":
         if (reqPath !== "/") { res.writeHead(404); return res.end("not found"); }
         res.writeHead(200, { "content-type": "text/html; charset=utf-8" });
-        return res.end(injectBase(r.h, baseHref));
+        return res.end(transformHtml(r.h, baseHref));
       case "s3": {
         const sub = subFolder(name);
         let base = r.s3; if (base.endsWith("/") && sub) base += sub + "/";
@@ -442,7 +468,7 @@ async function serve(res, name, reqPath, baseHref) {
         }
         const buf = Buffer.from(await up.arrayBuffer());
         let ct = up.headers.get("content-type"); if (!ct || ct === "application/octet-stream") ct = guess(key);
-        if (ct.includes("text/html")) { res.writeHead(up.status, { "content-type": ct }); return res.end(injectBase(buf.toString("utf8"), baseHref)); }
+        if (ct.includes("text/html")) { res.writeHead(up.status, { "content-type": ct }); return res.end(transformHtml(buf.toString("utf8"), baseHref)); }
         res.writeHead(up.status, { "content-type": ct }); return res.end(buf);
       }
       case "ip": {
@@ -464,7 +490,7 @@ async function serve(res, name, reqPath, baseHref) {
           if (lk === "content-type") continue;
           outHeaders[k] = v;
         }
-        if (ct.includes("text/html")) { res.writeHead(up.status, outHeaders); return res.end(injectBase(buf.toString("utf8"), baseHref)); }
+        if (ct.includes("text/html")) { res.writeHead(up.status, outHeaders); return res.end(transformHtml(buf.toString("utf8"), baseHref)); }
         res.writeHead(up.status, outHeaders); return res.end(buf);
       }
       case "p": {
@@ -483,7 +509,7 @@ async function serve(res, name, reqPath, baseHref) {
           if (lk === "content-type") continue;
           outHeaders[k] = v;
         }
-        if (ct.includes("text/html")) { res.writeHead(up.status, outHeaders); return res.end(injectBase(buf.toString("utf8"), baseHref)); }
+        if (ct.includes("text/html")) { res.writeHead(up.status, outHeaders); return res.end(transformHtml(buf.toString("utf8"), baseHref)); }
         res.writeHead(up.status, outHeaders); return res.end(buf);
       }
       case "u":