Rewrite congestion and recovery code

This is a very large change that replaces most of the congestion
and recovery control implementation with an implementation that
copies google/quiche for the most part. Most importantly cubic and
pacing are copied exactly from google/quiche so we can have a high
confidence in both. This fixes our pacing problems entirely and
also has a much cleaner interface, where every bit is cleanly separated
from the main state.

apps/src/bin/quiche-server.rs

@@ -542,10 +542,8 @@ fn main() {
                 client.loss_rate = loss_rate;
             }
 
-            let max_send_burst =
-                client.conn.send_quantum().min(client.max_send_burst) /
-                    client.max_datagram_size *
-                    client.max_datagram_size;
+            let max_send_burst = client.max_send_burst / client.max_datagram_size *
+                client.max_datagram_size;
             let mut total_write = 0;
             let mut dst_info = None;
 

apps/src/sendto.rs

@@ -59,6 +59,7 @@ fn send_to_gso_pacing(
     use nix::sys::socket::SockaddrStorage;
     use std::io::IoSlice;
     use std::os::unix::io::AsRawFd;
+    use std::time::Instant;
 
     let iov = [IoSlice::new(buf)];
     let segment_size = segment_size as u16;
@@ -69,7 +70,8 @@ fn send_to_gso_pacing(
     let cmsg_gso = ControlMessage::UdpGsoSegments(&segment_size);
 
     // Pacing option.
-    let send_time = std_time_to_u64(&send_info.at);
+    let now = Instant::now();
+    let send_time = std_time_to_u64(&send_info.release.time(now).unwrap_or(now));
     let cmsg_txtime = ControlMessage::TxTime(&send_time);
 
     match sendmsg(

quiche/.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "git-blame.gitWebUrl": ""
+}

quiche/Cargo.toml

@@ -68,6 +68,7 @@ intrusive-collections = "0.9.5"
 qlog = { version = "0.9", path = "../qlog", optional = true }
 sfv = { version = "0.9", optional = true }
 smallvec = { version = "1.10", features = ["serde", "union"] }
+enum_dispatch = "0.3"
 
 [target."cfg(windows)".dependencies]
 winapi = { version = "0.3", features = ["wincrypt", "ws2def", "ws2ipdef", "ws2tcpip"] }