+static int dtls1_query_mtu(SSL *s)
+{
+ if(s->d1->link_mtu)
+ {
+ s->d1->mtu = s->d1->link_mtu-BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
+ s->d1->link_mtu = 0;
+ }
+
+ /* AHA! Figure out the MTU, and stick to the right size */
+ if (s->d1->mtu < dtls1_min_mtu(s))
+ {
+ if(!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
+ {
+ s->d1->mtu =
+ BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
+
+ /* I've seen the kernel return bogus numbers when it doesn't know
+ * (initial write), so just make sure we have a reasonable number */
+ if (s->d1->mtu < dtls1_min_mtu(s))
+ {
+ /* Set to min mtu */
+ s->d1->mtu = dtls1_min_mtu(s);
+ BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
+ s->d1->mtu, NULL);
+ }
+ }
+ else
+ return 0;
+ }
+ return 1;
+}
+