api/stream: implement itunnel transplants

api/src/stream/internal.js

@@ -7,7 +7,7 @@ const CHUNK_SIZE = BigInt(8e6); // 8 MB
 const min = (a, b) => a < b ? a : b;
 
 async function* readChunks(streamInfo, size) {
-    let read = 0n;
+    let read = 0n, chunksSinceTransplant = 0;
     while (read < size) {
         if (streamInfo.controller.signal.aborted) {
             throw new Error("controller aborted");
@@ -22,6 +22,16 @@ async function* readChunks(streamInfo, size) {
             signal: streamInfo.controller.signal
         });
 
+        if (chunk.statusCode === 403 && chunksSinceTransplant >= 3 && streamInfo.transplant) {
+            chunksSinceTransplant = 0;
+            try {
+                await streamInfo.transplant(streamInfo.dispatcher);
+                continue;
+            } catch {}
+        }
+
+        chunksSinceTransplant++;
+
         const expected = min(CHUNK_SIZE, size - read);
         const received = BigInt(chunk.headers['content-length']);