do not treat txhashset.zip download as abusive behavior (#1973)

* do not treat txhashset.zip download as abusive behavior

* count times, not bytes so we exclude quiet increments

* use inc_quiet when tracking sent bytes via an attachment

* add comment

* fixup "quiet" counter entries

* rustfmt

p2p/src/conn.rs

@@ -140,9 +140,10 @@ impl<'a> Response<'a> {
 					Ok(0) => break,
 					Ok(n) => {
 						write_all(&mut self.conn, &buf[..n], time::Duration::from_secs(10))?;
-						// Increase sent bytes counter
+						// Increase sent bytes "quietly" without incrementing the counter.
+						// (In a loop here for the single attachment).
 						let mut sent_bytes = sent_bytes.write();
-						sent_bytes.inc(n as u64);
+						sent_bytes.inc_quiet(n as u64);
 					}
 					Err(e) => return Err(From::from(e)),
 				}

p2p/src/protocol.rs

@@ -300,10 +300,11 @@ impl MessageHandler for Protocol {
 							total_size as u64,
 						);
 
-						// Increase received bytes counter
+						// Increase received bytes quietly (without affecting the counters).
+						// Otherwise we risk banning a peer as "abusive".
 						{
 							let mut received_bytes = received_bytes.write();
-							received_bytes.inc(size as u64);
+							received_bytes.inc_quiet(size as u64);
 						}
 					}
 					tmp_zip.into_inner().unwrap().sync_all()?;

util/src/rate_counter.rs

@@ -15,44 +15,88 @@
 /// Utility to track the rate of data transfers
 use std::time::{Duration, SystemTime};
 
+struct Entry {
+	bytes: u64,
+	timestamp: u64,
+}
+
+impl Entry {
+	fn new(bytes: u64) -> Entry {
+		Entry {
+			bytes,
+			timestamp: millis_since_epoch(),
+		}
+	}
+
+	// Create new "quiet" entry with zero timestamp.
+	// This will count toward total bytes but will not affect the "msg rate".
+	fn new_quiet(bytes: u64) -> Entry {
+		Entry {
+			bytes,
+			timestamp: 0,
+		}
+	}
+
+	// We want to filter out "quiet" entries when calculating the "msg rate".
+	fn is_quiet(&self) -> bool {
+		self.timestamp == 0
+	}
+}
+
 /// A rate counter tracks the number of transfers, the amount of data
 /// exchanged and the rate of transfer (via a few timers) over the last
 /// minute. The counter does not try to be accurate and update times
 /// proactively, instead it only does so lazily. As a result, produced
 /// rates are worst-case estimates.
 pub struct RateCounter {
-	last_min_bytes: Vec<u64>,
-	last_min_times: Vec<u64>,
+	last_min_entries: Vec<Entry>,
 }
 
 impl RateCounter {
 	/// Instantiate a new rate counter
 	pub fn new() -> RateCounter {
 		RateCounter {
-			last_min_bytes: vec![],
-			last_min_times: vec![],
+			last_min_entries: vec![],
 		}
 	}
 
 	/// Increments number of bytes transferred, updating counts and rates.
 	pub fn inc(&mut self, bytes: u64) {
+		self.last_min_entries.push(Entry::new(bytes));
+		self.truncate();
+	}
+
+	/// Increments number of bytes without updating the count or rate.
+	/// We filter out 0 last_min_times when calculating rate.
+	/// Used during txhashset.zip download to track bytes downloaded
+	/// without treating a peer as abusive (too high a rate of download).
+	pub fn inc_quiet(&mut self, bytes: u64) {
+		self.last_min_entries.push(Entry::new_quiet(bytes));
+		self.truncate();
+	}
+
+	fn truncate(&mut self) {
 		let now_millis = millis_since_epoch();
-		self.last_min_times.push(now_millis);
-		self.last_min_bytes.push(bytes);
-		while self.last_min_times.len() > 0 && self.last_min_times[0] + 60000 < now_millis {
-			self.last_min_times.remove(0);
-			self.last_min_bytes.remove(0);
+		while self.last_min_entries.len() > 0
+			&& self.last_min_entries[0].timestamp + 60000 < now_millis
+		{
+			self.last_min_entries.remove(0);
 		}
 	}
 
-	/// Number of bytes counted in the last minute
+	/// Number of bytes counted in the last minute.
+	/// Includes "quiet" byte increments.
 	pub fn bytes_per_min(&self) -> u64 {
-		self.last_min_bytes.iter().sum()
+		self.last_min_entries.iter().map(|x| x.bytes).sum()
 	}
 
-	/// Count of increases in the last minute
+	/// Count of increases in the last minute.
+	/// Excludes "quiet" byte increments.
 	pub fn count_per_min(&self) -> u64 {
-		self.last_min_bytes.len() as u64
+		self.last_min_entries
+			.iter()
+			.filter(|x| !x.is_quiet())
+			.count() as u64
 	}
 }