Fix underscore name for a root domain

src/middlewares/extractValidatedName.js

@@ -20,7 +20,18 @@ function extractName(req) {
 
   let name = nameFromQueryOrBody;
   if (nameFromQueryOrBody === "_") {
-    name = validateAndReturnSubdomain(nonRootSubdomains);
+    if (!nonRootSubdomains) {
+      throw new AppError(
+        422,
+        "The _ format requires a corresponding subdomain as the NIP-05 name."
+      );
+    }
+
+    if (nonRootSubdomains === config.rootDomain) {
+      name = "_";
+    } else {
+      name = nonRootSubdomains;
+    }
   }
 
   return validateName(name);

src/nameRecord.js

@@ -29,13 +29,6 @@ export function validateName(name) {
     throw new AppError(422, "Name is required.");
   }
 
-  if (name.length < 3) {
-    throw new AppError(
-      422,
-      `Name '${name}' should have more than 3 characters.`
-    );
-  }
-
   if (name.startsWith("-")) {
     throw new AppError(422, `Name '${name}' should not start with a hyphen -.`);
   }
@@ -44,6 +37,17 @@ export function validateName(name) {
     throw new AppError(422, `Name '${name}' should not start with a hyphen -.`);
   }
 
+  if (name === "_") {
+    return name;
+  }
+
+  if (name.length < 3) {
+    throw new AppError(
+      422,
+      `Name '${name}' should have more than 3 characters.`
+    );
+  }
+
   if (name.includes("_")) {
     throw new AppError(
       422,

test/app.test.js

@@ -302,6 +302,36 @@ describe("Nostr NIP 05 API tests", () => {
     });
   });
 
+  it.only("should store and retrieve Nostr NIP 05 data through an empty subdomain", async () => {
+    const userData = createUserPayload({ name: "_" });
+
+    await request(app)
+      .post("/api/names")
+      .set("Host", "nos.social")
+      .set("Authorization", `Nostr ${nip98PostAuthToken}`)
+      .send(userData)
+      .expect(200);
+
+    const getResponse = await request(app)
+      .get("/.well-known/nostr.json")
+      .set("Host", "nos.social")
+      .query({ name: "_" })
+      .expect(200);
+
+    const jsonResponse = JSON.parse(getResponse.text);
+
+    expect(jsonResponse).toEqual({
+      names: { _: config.servicePubkey },
+      relays: {
+        [config.servicePubkey]: [
+          "wss://relay1.com",
+          "wss://relay2.com",
+          "wss://relay.nos.social",
+        ],
+      },
+    });
+  });
+
   it("should not use components of the root domain as a subdomain", async () => {
     const userData = createUserPayload({ name: "nos" });