ThreadCount Community edition

Uniform stock management for healthcare linen rooms: the coordinator app, the phone counter and the staff app, for your own server. Built from d947f89 on 2026-09-15. Licensed under the Functional Source License (FSL-1.1-ALv2).

lib/reset.ts

@@ -0,0 +1,65 @@
+import { createHash, randomBytes, timingSafeEqual } from "crypto";
+import { layout, siteUrl } from "@/lib/mail-html.cjs";
+
+/* Password reset tokens.
+ *
+ * The raw token is shown to exactly one person, once, in one email, and is never stored: the
+ * database keeps only its SHA-256. That matters because this table lands in every pg_dump, and a
+ * plaintext token in a leaked backup is a working key to an account until it expires.
+ *
+ * SHA-256 rather than bcrypt is the right call here, unusually: the token is 32 bytes of CSPRNG
+ * output, so there is no dictionary to attack and no need to be slow — and a reset lookup happens
+ * before the user is authenticated, where a deliberately slow hash is a denial-of-service lever. */
+
+/** One hour. Long enough to walk back to a desk, short enough that a forwarded email goes stale. */
+export const RESET_TTL_MS = 60 * 60 * 1000;
+
+export function newResetToken() {
+  const token = randomBytes(32).toString("base64url");
+  return { token, tokenHash: hashResetToken(token) };
+}
+
+export function hashResetToken(token: string) {
+  return createHash("sha256").update(token).digest("hex");
+}
+
+/** Constant-time compare, so a mismatched token can't be found a character at a time. */
+export function tokenMatches(a: string, b: string) {
+  const ab = Buffer.from(a, "utf8");
+  const bb = Buffer.from(b, "utf8");
+  if (ab.length !== bb.length) return false;
+  return timingSafeEqual(ab, bb);
+}
+
+/** The link a person clicks. Absolute, because it is going into an email client. */
+export function resetUrl(token: string) {
+  const base = process.env.NEXT_PUBLIC_SITE_URL || "https://threadcount.tech";
+  return `${base}/reset?token=${encodeURIComponent(token)}`;
+}
+
+export function resetEmail(firstName: string, url: string) {
+  const subject = "Reset your ThreadCount password";
+  const text = [
+    `Hi ${firstName || "there"},`,
+    "",
+    "Someone asked to reset the password on your ThreadCount account. If that was you, open this link:",
+    "",
+    url,
+    "",
+    "The link works once and expires in an hour.",
+    "",
+    "If it wasn't you, you can ignore this — your password hasn't changed, and nobody can get in without this link.",
+    "",
+    "— ThreadCount",
+  ].join("\n");
+  const { html } = layout({
+    eyebrow: "Your account",
+    title: "Reset your password",
+    preheader: "A password reset was asked for on your ThreadCount account. The link works once and expires in an hour.",
+    intro: [`Hi ${firstName || "there"},`, "Someone asked to reset the password on your ThreadCount account. If that was you, use the button below."],
+    cta: { label: "Reset my password", href: url },
+    closing: ["The link works once and expires in an hour.", "If it wasn't you, you can ignore this — your password hasn't changed, and nobody can get in without this link."],
+    footer: { links: [["Support", `${siteUrl()}/support`]] },
+  });
+  return { subject, text, html };
+}