feat: add new downloadSmallObject function that only hashes the data and compares it and does not verify it in real time

npm-shrinkwrap.json

@@ -12,7 +12,8 @@
                 "@lumeweb/libportal": "0.2.0-develop.17",
                 "@lumeweb/node-library-preset": "0.2.7",
                 "@noble/curves": "^1.1.0",
-                "@noble/hashes": "^1.3.1"
+                "@noble/hashes": "^1.3.1",
+                "binconv": "^0.2.0"
             },
             "devDependencies": {
                 "@semantic-release/changelog": "^6.0.3",
@@ -3814,6 +3815,11 @@
                 "node": ">=8"
             }
         },
+        "node_modules/binconv": {
+            "version": "0.2.0",
+            "resolved": "https://registry.npmjs.org/binconv/-/binconv-0.2.0.tgz",
+            "integrity": "sha512-FAVbv8Fe1lsk1XQeWaYzfIQ9EnBgLJxjlqVA5XzbusP1YCzFgXUfIfmuanNmfM7i0XsNCNnYOnnq7NRLVKRgdQ=="
+        },
         "node_modules/bottleneck": {
             "version": "2.19.5",
             "resolved": "https://registry.npmjs.org/bottleneck/-/bottleneck-2.19.5.tgz",

package.json

@@ -25,7 +25,8 @@
         "@lumeweb/libportal": "0.2.0-develop.17",
         "@lumeweb/node-library-preset": "0.2.7",
         "@noble/curves": "^1.1.0",
-        "@noble/hashes": "^1.3.1"
+        "@noble/hashes": "^1.3.1",
+        "binconv": "^0.2.0"
     },
     "publishConfig": {
         "access": "public"

src/download.ts

@@ -1,6 +1,12 @@
 import { getActivePortals } from "#portal.js";
 import { ErrTuple } from "#types.js";
 import { decodeCid, getVerifiableStream } from "@lumeweb/libportal";
+import {
+  readableStreamToUint8Array,
+  uint8ArrayToReadableStream,
+} from "binconv";
+import { equalBytes } from "@noble/curves/abstract/utils";
+import { blake3 } from "@noble/hashes/blake3";
 
 const NO_PORTALS_ERROR = [null, "no active portals"] as ErrTuple;
 
@@ -37,3 +43,40 @@ export async function downloadObject(cid: string): Promise<ErrTuple> {
 
   return NO_PORTALS_ERROR;
 }
+
+export async function downloadSmallObject(cid: string): Promise<ErrTuple> {
+  const activePortals = getActivePortals();
+
+  if (!activePortals.length) {
+    return NO_PORTALS_ERROR;
+  }
+
+  for (const portal of activePortals) {
+    if (!(await portal.isLoggedIn())) {
+      try {
+        await portal.register();
+      } catch {}
+
+      await portal.login();
+    }
+
+    let stream;
+
+    try {
+      stream = await portal.downloadFile(cid);
+    } catch {
+      continue;
+    }
+
+    const CID = decodeCid(cid);
+    const data = await readableStreamToUint8Array(stream);
+
+    if (!equalBytes(blake3(data), CID.hash)) {
+      return [null, "cid verification failed"];
+    }
+
+    return [uint8ArrayToReadableStream(data), null];
+  }
+
+  return NO_PORTALS_ERROR;
+}