From 31d2586e3296d424e51848ada963299b0da89324 Mon Sep 17 00:00:00 2001
From: Dirk Engling <erdgeist@erdgeist.org>
Date: Fri, 30 Oct 2026 13:23:39 +0100
Subject: Defer accepts until some data actually is there

---
 ot_socket.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'ot_socket.c')

diff --git a/ot_socket.c b/ot_socket.c
index 47ed26d..78a16d2 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 +121,25 @@ 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;
+
+  memset(&filter, 0, sizeof(filter));
+  strcpy(filter.af_name, "httpready");
+  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);
 
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