2 files changed, 13 insertions, 1 deletions

diff --git a/man4/opentracker.conf.4 b/man4/opentracker.conf.4
index b28879f..aa82e1d 100644
--- a/man4/opentracker.conf.4
+++ b/man4/opentracker.conf.4
@@ -100,6 +100,17 @@ group only where the answer is yes.
 .Pa tests/udp_scaling.py
 in the source distribution sweeps the setting against a running tracker.
 Measure on the machine that will carry the traffic.
+.Pp
+On FreeBSD the
+.Xr accf_data 9
+filter has the kernel hold a new connection until data arrives on it, so the
+tracker is woken once with the request already there. opentracker uses it
+wherever it is available; enable it with
+.Cm options ACCEPT_FILTER_DATA
+in the kernel or
+.Va kld_list Ns = Ns Qq accf_data
+in
+.Xr rc.conf 5 .
 .Sh EXAMPLES
 To specify the address opentracker will listen on for both TCP and UDP connections:
 .Dl listen.tcp_udp 0.0.0.0:6969
diff --git a/ot_socket.c b/ot_socket.c
index 78a16d2..48ffc27 100644
--- a/ot_socket.c
+++ b/ot_socket.c
@@ -130,9 +130,10 @@ int socket_defer_accept(int s) {
   return setsockopt(s, IPPROTO_TCP, TCP_DEFER_ACCEPT, &patience, sizeof(patience));
 #elif defined(SO_ACCEPTFILTER)
   struct accept_filter_arg filter;
+  const char               name[sizeof(filter.af_name)] = "dataready";
 
   memset(&filter, 0, sizeof(filter));
-  strcpy(filter.af_name, "httpready");
+  memcpy(filter.af_name, name, sizeof(name));
   return setsockopt(s, SOL_SOCKET, SO_ACCEPTFILTER, &filter, sizeof(filter));
 #else
   (void)s;