Prevent a node from overrunning it's receive window (#846)

- The node drops blobs that will cause it to overrun window
- The node does not ask to repair a blob that overruns the window

src/streamer.rs

@@ -211,7 +211,12 @@ fn calculate_highest_lost_blob_index(num_peers: u64, consumed: u64, received: u6
     // via avalanche. The avalanche splits data stream into nodes and each node retransmits
     // the data to their peer nodes. So there's a possibility that a blob (with index lower
     // than current received index) is being retransmitted by a peer node.
-    cmp::max(consumed, received.saturating_sub(num_peers))
+    let highest_lost = cmp::max(consumed, received.saturating_sub(num_peers));
+
+    // This check prevents repairing a blob that will cause window to roll over. Even if
+    // the highes_lost blob is actually missing, asking to repair it might cause our
+    // current window to move past other missing blobs
+    cmp::min(consumed + WINDOW_SIZE - 1, highest_lost)
 }
 
 fn repair_window(
@@ -484,6 +489,11 @@ fn recv_window(
             let p = b.write().expect("'b' write lock in fn recv_window");
             (p.get_index()?, p.meta.size)
         };
+        // Prevent receive window from running over
+        if pix >= *consumed + WINDOW_SIZE {
+            recycler.recycle(b);
+            continue;
+        }
         if pix > *received {
             *received = pix;
         }
@@ -921,7 +931,7 @@ mod test {
     use std::time::Duration;
     use streamer::calculate_highest_lost_blob_index;
     use streamer::{blob_receiver, receiver, responder, window};
-    use streamer::{default_window, BlobReceiver, PacketReceiver};
+    use streamer::{default_window, BlobReceiver, PacketReceiver, WINDOW_SIZE};
 
     fn get_msgs(r: PacketReceiver, num: &mut usize) {
         for _t in 0..5 {
@@ -1080,5 +1090,21 @@ mod test {
         assert_eq!(calculate_highest_lost_blob_index(90, 10, 50), 10);
         assert_eq!(calculate_highest_lost_blob_index(90, 10, 99), 10);
         assert_eq!(calculate_highest_lost_blob_index(90, 10, 101), 11);
+        assert_eq!(
+            calculate_highest_lost_blob_index(90, 10, 95 + WINDOW_SIZE),
+            WINDOW_SIZE + 5
+        );
+        assert_eq!(
+            calculate_highest_lost_blob_index(90, 10, 99 + WINDOW_SIZE),
+            WINDOW_SIZE + 9
+        );
+        assert_eq!(
+            calculate_highest_lost_blob_index(90, 10, 100 + WINDOW_SIZE),
+            WINDOW_SIZE + 9
+        );
+        assert_eq!(
+            calculate_highest_lost_blob_index(90, 10, 120 + WINDOW_SIZE),
+            WINDOW_SIZE + 9
+        );
     }
 }