Certificate export, missing PTR list, simpler "Used for"

- Certificates can be exported for use outside Jarl: Export… on the
  Certificates page (download or copy), jarl cert export, and
  GET /certificates/{name}/pem?part=fullchain|cert|key|bundle.
  Administrators only; key exports are audited.
- A reverse zone's missing-PTR banner lists the addresses and names
  (ptr_missing_list in the zone API).
- "Used for" shows DoT/DoH for named, and "not used by Jarl" instead of
  "nothing yet".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/web/static/assets/pages/certificates.js

@@ -32,10 +32,9 @@ export async function render(el) {
     { label: "Name", render: (c) => h("a", { href: "#", onclick: (e) => { e.preventDefault(); details(c); } }, h("strong", null, c.name)) },
     { label: "Names", render: (c) => h("div", { class: "mono small" }, (c.names && c.names.length ? c.names : c.domains).map((n) => h("div", null, n))) },
     { label: "Used for", render: (c) => [
-      c.uses.includes("web") ? badge(c.serving ? "web UI (serving)" : "web UI", c.serving ? "ok" : "") : null, " ",
-      c.uses.includes("dns") ? [badge("named", ""), (c.named_use || []).map((u) => h("div", { class: "small muted", title: u }, u.replace("DNS over TLS on ", "DoT ").replace("DNS over HTTPS on ", "DoH "))),
-        !(c.named_use || []).length ? h("div", { class: "small muted" }, "not used by named yet") : null] : null,
-      !c.uses.length ? h("span", { class: "muted" }, "nothing yet") : null] },
+      c.uses.includes("web") ? [badge(c.serving ? "web UI (serving)" : "web UI", c.serving ? "ok" : ""), " "] : null,
+      c.uses.includes("dns") ? namedUse(c) : null,
+      !c.uses.length ? h("span", { class: "muted", title: "Export it to use it in another program" }, "not used by Jarl") : null] },
     { label: "Source", render: (c) => c.source === "acme" ? h("span", null, "Jarl", h("div", { class: "small muted" }, "challenge " + c.challenge)) : h("span", null, "your files", h("div", { class: "small muted mono" }, c.cert_file)) },
     { label: "Expires", render: (c) => c.not_after ? h("span", null, time(c.not_after), c.source === "acme" && c.next_attempt ? h("div", { class: "small muted" }, "renews " + fmtTime(c.next_attempt)) : null) : h("span", { class: "muted" }, "–") },
     { label: "Status", render: (c) => {
@@ -45,6 +44,7 @@ export async function render(el) {
     { label: "", render: (c) => h("span", null,
       h("button", { class: "small", disabled: !!c.issuing_since, title: c.source === "acme" ? "Obtain a new certificate now" : "Reread the files now", onclick: () => issue(c) }, c.source === "acme" ? "Renew" : "Reread"), " ",
       h("button", { class: "small", onclick: () => editDialog(c, a) }, "Edit"), " ",
+      c.not_after ? [h("button", { class: "small", title: "Download it to use in another program", onclick: () => exportDialog(c) }, "Export…"), " "] : null,
       h("button", { class: "small danger", onclick: () => del(c) }, "Delete")), tdClass: "actions-cell" },
   ], r.certificates, { empty: "No certificates yet." })));
 
@@ -64,6 +64,15 @@ export async function render(el) {
   }
 }
 
+// namedUse is what named uses a certificate for: DoT and DoH, with the
+// addresses in the tooltip (the details list them).
+function namedUse(c) {
+  const uses = c.named_use || [];
+  if (!uses.length) return h("span", { class: "muted", title: "Encrypted DNS sets up named's DNS over TLS and HTTPS" }, "named: not set up");
+  const kinds = [["DNS over TLS", "DoT"], ["DNS over HTTPS", "DoH"]].filter(([long]) => uses.some((u) => u.startsWith(long)));
+  return h("span", { title: uses.join("\n") }, kinds.map(([, short]) => [badge(short, ""), " "]));
+}
+
 function details(c) {
   const rows = [
     ["Source", c.source === "acme" ? "Jarl obtains and renews it (" + c.key_type + " key)" : "your files: " + c.cert_file + ", " + c.key_file],
@@ -85,6 +94,62 @@ function details(c) {
       copyBox(c.files.chain), copyBox(c.files.key)) : null), [{ label: "Close", value: null }], { wide: true });
 }
 
+// exportDialog downloads a certificate's files to use elsewhere.
+function exportDialog(c) {
+  const parts = [
+    ["fullchain", "fullchain.pem", "the certificate and its chain: what most programs want"],
+    ["cert", "cert.pem", "the certificate alone"],
+    ["key", "privkey.pem", "the private key"],
+    ["bundle", "bundle.pem", "the key, then the chain, in one file (HAProxy)"],
+  ];
+  modal("Export certificate " + c.name, h("div", null,
+    c.source === "acme"
+      ? h("p", null, "For a program outside Jarl (a mail server, a reverse proxy). Jarl renews the certificate, but not your copy: export it again after each renewal",
+        c.next_attempt ? " (next: " + fmtTime(c.next_attempt) + ")" : "", ", or have the program read the files Jarl writes for named (use it for named).")
+      : h("p", null, "For a program outside Jarl (a mail server, a reverse proxy). You renew this one yourself, so a program on this server can read your files directly: ", h("code", null, c.cert_file), "."),
+    h("table", { class: "small" }, parts.map(([part, file, what]) => h("tr", null,
+      h("td", null, h("button", { class: "small" + (part === "fullchain" ? " primary" : ""), title: "Download " + file, onclick: () => download(c, part, file) }, file), " ",
+        h("button", { class: "small", title: "Copy " + file + " to the clipboard", onclick: () => copyPEM(c, part, file) }, "Copy")),
+      h("td", { class: part === "key" || part === "bundle" ? "" : "muted" }, what, part === "key" || part === "bundle" ? h("span", { class: "muted" }, " (audited)") : null)))),
+    h("p", { class: "small muted" }, "CLI: ", h("code", null, "jarl cert export " + c.name + " --dir DIR"))), [{ label: "Close", value: null }]);
+}
+
+// fetchPEM gets one part of a certificate, after asking when it holds the
+// private key (verb: "Download" or "Copy"). null when not confirmed.
+async function fetchPEM(c, part, verb) {
+  if ((part === "key" || part === "bundle") && !await confirmDialog(verb + " the private key",
+    "Whoever has the key of " + c.name + " can pose as " + (c.names || c.domains || []).join(", ") + " until the certificate expires. Keep it as safe as the server keeps it" +
+    (verb === "Copy" ? ", and clear it from the clipboard when you're done (clipboard managers keep a history)" : "") + ". This is recorded in the audit log.", verb)) return null;
+  const resp = await fetch("/api/v1/certificates/" + encodeURIComponent(c.name) + "/pem?part=" + part, { credentials: "same-origin" });
+  if (!resp.ok) {
+    let msg = "HTTP " + resp.status;
+    try { msg = (await resp.json()).error.message; } catch { /* not JSON */ }
+    throw new Error(msg);
+  }
+  return resp.text();
+}
+
+async function copyPEM(c, part, file) {
+  try {
+    const text = await fetchPEM(c, part, "Copy");
+    if (text === null) return;
+    if (!navigator.clipboard) throw new Error("the browser allows copying only over HTTPS (or from localhost); download it instead");
+    await navigator.clipboard.writeText(text);
+    toast("Copied " + file);
+  } catch (e) { toast("Copy failed: " + e.message, "err", 8000); }
+}
+
+async function download(c, part, file) {
+  try {
+    const text = await fetchPEM(c, part, "Download");
+    if (text === null) return;
+    const a = h("a", { href: URL.createObjectURL(new Blob([text], { type: "application/x-pem-file" })), download: c.name + "-" + file });
+    document.body.append(a);
+    a.click();
+    a.remove();
+  } catch (e) { toast(e.message, "err", 8000); }
+}
+
 async function issue(c) {
   try {
     const r = await api("POST", "/certificates/" + encodeURIComponent(c.name) + "/issue", { body: {} });