timer_cb
DTLS_timer_cb timer_cb = s->d1->timer_cb;
s->d1->timer_cb = timer_cb;
if (s->d1->timer_cb != NULL)
s->d1->timeout_duration_us = s->d1->timer_cb(ssl, 0);
if (s->d1->timer_cb != NULL)
s->d1->timeout_duration_us = s->d1->timer_cb(SSL_CONNECTION_GET_USER_SSL(s),
s->d1->timer_cb = cb;
DTLS_timer_cb timer_cb;
DTLS_set_timer_cb(clientssl1, timer_cb);
DTLS_set_timer_cb(clientssl, timer_cb);
DTLS_set_timer_cb(serverssl, timer_cb);
DTLS_set_timer_cb(clientssl, timer_cb);
DTLS_set_timer_cb(serverssl, timer_cb);
DTLS_set_timer_cb(serverssl, timer_cb);
DTLS_set_timer_cb(clientssl, timer_cb);
DTLS_set_timer_cb(serverssl, timer_cb);