1 files changed, 21 insertions, 0 deletions

diff --git a/ot_socket.c b/ot_socket.c
index 47ed26d..48ffc27 100644
--- a/ot_socket.c
+++ b/ot_socket.c
@@ -8,6 +8,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <netinet/in.h>
+#include <netinet/tcp.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <unistd.h>
@@ -120,6 +121,26 @@ static int socket_bind_v6(int s, const ot_ip6 ip, uint16_t port, socket_sharing
   return bind(s, (struct sockaddr *)&sa, sizeof(sa));
 }
 
+/* Defer the listening socket reporting it to be ready to accept until enough
+   sensible data is available for an accept+read pair. Where available. */
+int socket_defer_accept(int s) {
+#if defined(TCP_DEFER_ACCEPT)
+  int patience = OT_CLIENT_TIMEOUT;
+
+  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));
+  memcpy(filter.af_name, name, sizeof(name));
+  return setsockopt(s, SOL_SOCKET, SO_ACCEPTFILTER, &filter, sizeof(filter));
+#else
+  (void)s;
+  return -1;
+#endif
+}
+
 int socket_tcp_listen(const ot_ip6 ip, uint16_t port, socket_sharing sharing) {
   int s = socket_v6(SOCK_STREAM);