Use TCP BBR in a best-effort mode

This small commits conditionally sets TCP BBR as a preferrable algorithm
for TCP congestion control

network/v2/sockopts.go

@@ -28,5 +28,7 @@ func setCommonSocketOptions(conn *net.TCPConn) error {
 		return fmt.Errorf("cannot setup SO_REUSEADDR/PORT: %w", err)
 	}
 
+	setCongestionControl(rawConn)
+
 	return nil
 }

network/v2/sockopts_linux.go

@@ -0,0 +1,19 @@
+//go:build linux
+
+package network
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+func setCongestionControl(conn syscall.RawConn) {
+	conn.Control(func(fd uintptr) { //nolint: errcheck
+		// BBR provides better throughput over lossy and high-latency links compared
+		// to the default cubic, which is especially beneficial for mobile and
+		// home internet clients. This is best-effort: silently ignored if the
+		// kernel does not have tcp_bbr available.
+		unix.SetsockoptString(int(fd), unix.IPPROTO_TCP, unix.TCP_CONGESTION, "bbr") //nolint: errcheck
+	})
+}

network/v2/sockopts_nolinux.go

@@ -0,0 +1,7 @@
+//go:build !linux
+
+package network
+
+import "syscall"
+
+func setCongestionControl(conn syscall.RawConn) {}