From b0fe52ba4ee6a826bafaf4c6a14b33ecb1d77b7a Mon Sep 17 00:00:00 2001
From: Jack Lau <jacklau1222gm@gmail.com>
Date: Sat, 10 Jan 2026 20:37:08 +0800
Subject: [PATCH] avformat/tls_gnutls: add gnutls_pull_timeout() for dtls

See https://gnutls.org/manual/gnutls.html#index-gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction

This callback is necessary for enforcing the DTLS mode timeouts when in blocking mode.

Otherwise the dtls pull function won't work.

The gnutls_pull_timeout() implementation refers to gnutls example:
https://gnutls.org/manual/gnutls.html#DTLS-echo-server-with-X_002e509-authentication-1

Signed-off-by: Jack Lau <jacklau1222gm@gmail.com>
---
 libavformat/tls_gnutls.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/libavformat/tls_gnutls.c b/libavformat/tls_gnutls.c
index c991a712df..6f58ec03d2 100644
--- a/libavformat/tls_gnutls.c
+++ b/libavformat/tls_gnutls.c
@@ -167,6 +167,29 @@ static ssize_t gnutls_url_push(gnutls_transport_ptr_t transport,
     return -1;
 }
 
+static int gnutls_pull_timeout(gnutls_transport_ptr_t ptr, unsigned int ms)
+{
+    TLSContext *c = (TLSContext*) ptr;
+    TLSShared *s = &c->tls_shared;
+    int ret;
+    fd_set rfds;
+    struct timeval tv;
+    int sockfd = ffurl_get_file_handle(s->udp);
+    if (sockfd < 0)
+        return 0;
+
+    FD_ZERO(&rfds);
+    FD_SET(sockfd, &rfds);
+
+    tv.tv_sec = ms / 1000;
+    tv.tv_usec = (ms % 1000) * 1000;
+
+    ret = select(sockfd + 1, &rfds, NULL, NULL, &tv);
+    if (ret <= 0)
+        return ret;
+    return 1;
+}
+
 static int tls_handshake(URLContext *h)
 {
     TLSContext *c = h->priv_data;
@@ -244,9 +267,11 @@ static int tls_open(URLContext *h, const char *uri, int flags, AVDictionary **op
     gnutls_transport_set_pull_function(c->session, gnutls_url_pull);
     gnutls_transport_set_push_function(c->session, gnutls_url_push);
     gnutls_transport_set_ptr(c->session, c);
-    if (s->is_dtls)
+    if (s->is_dtls) {
+        gnutls_transport_set_pull_timeout_function(c->session, gnutls_pull_timeout);
         if (s->mtu)
             gnutls_dtls_set_mtu(c->session, s->mtu);
+    }
     gnutls_set_default_priority(c->session);
     ret = tls_handshake(h);
     if (ret < 0)