fix(iroh): handle out of bounds requests for blobs read_at (#2729)

Closes #2728

iroh/src/client/blobs.rs

@@ -1168,6 +1168,21 @@ mod tests {
         assert_eq!(reader.size(), 1024 * 128);
         assert_eq!(reader.response_size, 20);
 
+        // out of bounds - too long
+        let res = client.blobs().read_at(hash, 0, Some(1024 * 128 + 1)).await;
+        let err = res.unwrap_err();
+        assert!(err.to_string().contains("out of bound"));
+
+        // out of bounds - offset larger than blob
+        let res = client.blobs().read_at(hash, 1024 * 128 + 1, None).await;
+        let err = res.unwrap_err();
+        assert!(err.to_string().contains("out of range"));
+
+        // out of bounds - offset + length too large
+        let res = client.blobs().read_at(hash, 1024 * 127, Some(1025)).await;
+        let err = res.unwrap_err();
+        assert!(err.to_string().contains("out of bound"));
+
         Ok(())
     }
 

iroh/src/node/rpc.rs

@@ -1230,15 +1230,31 @@ impl<D: BaoStore> Handler<D> {
             let entry = db.get(&req.hash).await?;
             let entry = entry.ok_or_else(|| anyhow!("Blob not found"))?;
             let size = entry.size();
+
+            anyhow::ensure!(
+                req.offset <= size.value(),
+                "requested offset is out of range: {} > {:?}",
+                req.offset,
+                size
+            );
+
+            let len = req.len.unwrap_or((size.value() - req.offset) as usize);
+
+            anyhow::ensure!(
+                req.offset + len as u64 <= size.value(),
+                "requested range is out of bounds: offset: {}, len: {} > {:?}",
+                req.offset,
+                len,
+                size
+            );
+
             tx.send(Ok(ReadAtResponse::Entry {
                 size,
                 is_complete: entry.is_complete(),
             }))
             .await?;
             let mut reader = entry.data_reader().await?;
 
-            let len = req.len.unwrap_or((size.value() - req.offset) as usize);
-
             let (num_chunks, chunk_size) = if len <= max_chunk_size {
                 (1, len)
             } else {