DTLS handshake fragmentation

[ibc]

https://tools.ietf.org/html/rfc6347#section-4.2.2

Solution in OpenSSL:

#define RTPPAYLOADSIZE 1350

// Disable automatic MTU discovery.
SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_QUERY_MTU);

// Set MTU of datagrams so it fits in an UDP packet.
SSL_set_mtu(ssl, RTPPAYLOADSIZE);
// DTLS_set_link_mtu(ssl, MTU);   // ¿?¿?¿?
BIO_ctrl(write_bio, BIO_CTRL_DGRAM_SET_MTU, RTPPAYLOADSIZE, NULL);

[ibc]

Also consider: openssl/openssl#346