From a15fa4840c45964390e2aab1d5d8214204e76230 Mon Sep 17 00:00:00 2001
From: sakridge <sakridge@gmail.com>
Date: Wed, 1 Apr 2020 06:48:35 -0700
Subject: [PATCH] Fix repair dos (#9056)

---
 core/src/serve_repair.rs | 60 ++++++++++++++++++++++++++++------------
 1 file changed, 43 insertions(+), 17 deletions(-)

diff --git a/core/src/serve_repair.rs b/core/src/serve_repair.rs
index c0a55143eb6d46..721e05cc600618 100644
--- a/core/src/serve_repair.rs
+++ b/core/src/serve_repair.rs
@@ -9,6 +9,7 @@ use crate::{
 use bincode::serialize;
 use rand::{thread_rng, Rng};
 use solana_ledger::blockstore::Blockstore;
+use solana_measure::measure::Measure;
 use solana_measure::thread_mem_usage;
 use solana_metrics::{datapoint_debug, inc_new_counter_debug};
 use solana_perf::packet::{Packets, PacketsRecycler};
@@ -184,12 +185,33 @@ impl ServeRepair {
         blockstore: Option<&Arc<Blockstore>>,
         requests_receiver: &PacketReceiver,
         response_sender: &PacketSender,
+        max_packets: &mut usize,
     ) -> Result<()> {
         //TODO cache connections
         let timeout = Duration::new(1, 0);
-        let reqs = requests_receiver.recv_timeout(timeout)?;
+        let mut reqs_v = vec![requests_receiver.recv_timeout(timeout)?];
+        let mut total_packets = reqs_v[0].packets.len();
+
+        while let Ok(more) = requests_receiver.try_recv() {
+            total_packets += more.packets.len();
+            if total_packets < *max_packets {
+                // Drop the rest in the channel in case of dos
+                reqs_v.push(more);
+            }
+        }
 
-        Self::handle_packets(obj, &recycler, blockstore, reqs, response_sender);
+        let mut time = Measure::start("repair::handle_packets");
+        for reqs in reqs_v {
+            Self::handle_packets(obj, &recycler, blockstore, reqs, response_sender);
+        }
+        time.stop();
+        if total_packets >= *max_packets {
+            if time.as_ms() > 1000 {
+                *max_packets = (*max_packets * 9) / 10;
+            } else {
+                *max_packets = (*max_packets * 10) / 9;
+            }
+        }
         Ok(())
     }
 
@@ -204,22 +226,26 @@ impl ServeRepair {
         let recycler = PacketsRecycler::default();
         Builder::new()
             .name("solana-repair-listen".to_string())
-            .spawn(move || loop {
-                let result = Self::run_listen(
-                    &me,
-                    &recycler,
-                    blockstore.as_ref(),
-                    &requests_receiver,
-                    &response_sender,
-                );
-                match result {
-                    Err(Error::RecvTimeoutError(_)) | Ok(_) => {}
-                    Err(err) => info!("repair listener error: {:?}", err),
-                };
-                if exit.load(Ordering::Relaxed) {
-                    return;
+            .spawn(move || {
+                let mut max_packets = 1024;
+                loop {
+                    let result = Self::run_listen(
+                        &me,
+                        &recycler,
+                        blockstore.as_ref(),
+                        &requests_receiver,
+                        &response_sender,
+                        &mut max_packets,
+                    );
+                    match result {
+                        Err(Error::RecvTimeoutError(_)) | Ok(_) => {}
+                        Err(err) => info!("repair listener error: {:?}", err),
+                    };
+                    if exit.load(Ordering::Relaxed) {
+                        return;
+                    }
+                    thread_mem_usage::datapoint("solana-repair-listen");
                 }
-                thread_mem_usage::datapoint("solana-repair-listen");
             })
             .unwrap()
     }