+ /*
+ * We don't support fragment reassembly for ClientHellos whilst
+ * listening because that would require server side state (which is
+ * against the whole point of the ClientHello/HelloVerifyRequest
+ * mechanism). Instead we only look at the first ClientHello fragment
+ * and require that the cookie must be contained within it.
+ */
+ if (fragoff != 0 || fraglen > msglen) {
+ /* Non initial ClientHello fragment (or bad fragment) */
+ SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO);
+ goto end;
+ }
+
+ if (s->msg_callback)
+ s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
+ fraglen + DTLS1_HM_HEADER_LENGTH, s,
+ s->msg_callback_arg);
+
+ if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
+ SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
+ goto end;
+ }
+
+ /*
+ * Verify client version is supported
+ */
+ if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) &&
+ s->method->version != DTLS_ANY_VERSION) {
+ SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER);
+ goto end;
+ }
+
+ if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
+ || !PACKET_get_length_prefixed_1(&msgpayload, &session)
+ || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
+ /*
+ * Could be malformed or the cookie does not fit within the initial
+ * ClientHello fragment. Either way we can't handle it.
+ */
+ SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
+ goto end;
+ }
+
+ /*
+ * Check if we have a cookie or not. If not we need to send a
+ * HelloVerifyRequest.
+ */
+ if (PACKET_remaining(&cookiepkt) == 0) {
+ next = LISTEN_SEND_VERIFY_REQUEST;
+ } else {
+ /*
+ * We have a cookie, so lets check it.
+ */
+ if (s->ctx->app_verify_cookie_cb == NULL) {
+ SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
+ /* This is fatal */
+ return -1;
+ }
+ if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt),
+ (unsigned int)PACKET_remaining(&cookiepkt)) == 0) {
+ /*
+ * We treat invalid cookies in the same was as no cookie as
+ * per RFC6347
+ */
+ next = LISTEN_SEND_VERIFY_REQUEST;
+ } else {
+ /* Cookie verification succeeded */
+ next = LISTEN_SUCCESS;
+ }
+ }
+
+ if (next == LISTEN_SEND_VERIFY_REQUEST) {
+ WPACKET wpkt;
+ unsigned int version;
+ size_t wreclen;
+
+ /*
+ * There was no cookie in the ClientHello so we need to send a
+ * HelloVerifyRequest. If this fails we do not worry about trying
+ * to resend, we just drop it.
+ */
+
+ /*
+ * Dump the read packet, we don't need it any more. Ignore return
+ * value
+ */
+ BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL);
+ BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
+ BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL);
+
+ /* Generate the cookie */
+ if (s->ctx->app_gen_cookie_cb == NULL ||
+ s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 ||
+ cookielen > 255) {
+ SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
+ /* This is fatal */
+ return -1;
+ }
+
+ /*
+ * Special case: for hello verify request, client version 1.0 and we
+ * haven't decided which version to use yet send back using version
+ * 1.0 header: otherwise some clients will ignore it.
+ */
+ version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION
+ : s->version;
+
+ /* Construct the record and message headers */
+ if (!WPACKET_init(&wpkt, s->init_buf)
+ || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE)
+ || !WPACKET_put_bytes_u16(&wpkt, version)
+ /*
+ * Record sequence number is always the same as in the
+ * received ClientHello
+ */
+ || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE)
+ /* End of record, start sub packet for message */
+ || !WPACKET_start_sub_packet_u16(&wpkt)
+ /* Message type */
+ || !WPACKET_put_bytes_u8(&wpkt,
+ DTLS1_MT_HELLO_VERIFY_REQUEST)
+ /*
+ * Message length - doesn't follow normal TLS convention:
+ * the length isn't the last thing in the message header.
+ * We'll need to fill this in later when we know the
+ * length. Set it to zero for now
+ */
+ || !WPACKET_put_bytes_u24(&wpkt, 0)
+ /*
+ * Message sequence number is always 0 for a
+ * HelloVerifyRequest
+ */
+ || !WPACKET_put_bytes_u16(&wpkt, 0)
+ /*
+ * We never fragment a HelloVerifyRequest, so fragment
+ * offset is 0
+ */
+ || !WPACKET_put_bytes_u24(&wpkt, 0)
+ /*
+ * Fragment length is the same as message length, but
+ * this *is* the last thing in the message header so we
+ * can just start a sub-packet. No need to come back
+ * later for this one.
+ */
+ || !WPACKET_start_sub_packet_u24(&wpkt)
+ /* Create the actual HelloVerifyRequest body */
+ || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen)
+ /* Close message body */
+ || !WPACKET_close(&wpkt)
+ /* Close record body */
+ || !WPACKET_close(&wpkt)
+ || !WPACKET_get_total_written(&wpkt, &wreclen)
+ || !WPACKET_finish(&wpkt)) {
+ SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
+ WPACKET_cleanup(&wpkt);
+ /* This is fatal */
+ return -1;
+ }
+
+ /*
+ * Fix up the message len in the message header. Its the same as the
+ * fragment len which has been filled in by WPACKET, so just copy
+ * that. Destination for the message len is after the record header
+ * plus one byte for the message content type. The source is the
+ * last 3 bytes of the message header
+ */
+ memcpy(&buf[DTLS1_RT_HEADER_LENGTH + 1],
+ &buf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3],
+ 3);
+
+ if (s->msg_callback)
+ s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
+ DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
+
+ if ((tmpclient = BIO_ADDR_new()) == NULL) {
+ SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
+ goto end;
+ }
+
+ /*
+ * This is unnecessary if rbio and wbio are one and the same - but
+ * maybe they're not. We ignore errors here - some BIOs do not
+ * support this.
+ */
+ if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
+ (void)BIO_dgram_set_peer(wbio, tmpclient);
+ }
+ BIO_ADDR_free(tmpclient);
+ tmpclient = NULL;
+
+ /* TODO(size_t): convert this call */
+ if (BIO_write(wbio, buf, wreclen) < (int)wreclen) {
+ if (BIO_should_retry(wbio)) {
+ /*
+ * Non-blocking IO...but we're stateless, so we're just
+ * going to drop this packet.
+ */
+ goto end;
+ }
+ return -1;
+ }
+
+ if (BIO_flush(wbio) <= 0) {
+ if (BIO_should_retry(wbio)) {
+ /*
+ * Non-blocking IO...but we're stateless, so we're just
+ * going to drop this packet.
+ */
+ goto end;
+ }
+ return -1;
+ }
+ }
+ } while (next != LISTEN_SUCCESS);
+
+ /*
+ * Set expected sequence numbers to continue the handshake.
+ */
+ s->d1->handshake_read_seq = 1;
+ s->d1->handshake_write_seq = 1;
+ s->d1->next_handshake_write_seq = 1;
+ DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq);
+
+ /*
+ * We are doing cookie exchange, so make sure we set that option in the
+ * SSL object
+ */
+ SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
+
+ /*
+ * Tell the state machine that we've done the initial hello verify
+ * exchange
+ */
+ ossl_statem_set_hello_verify_done(s);
+
+ /*
+ * Some BIOs may not support this. If we fail we clear the client address
+ */
+ if (BIO_dgram_get_peer(rbio, client) <= 0)
+ BIO_ADDR_clear(client);
+
+ ret = 1;
+ clearpkt = 0;
+ end:
+ BIO_ADDR_free(tmpclient);
+ BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL);
+ if (clearpkt) {
+ /* Dump this packet. Ignore return value */
+ BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
+ }
+ return ret;
+}
+#endif
+
+static int dtls1_handshake_write(SSL *s)
+{
+ return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
+}
+
+int dtls1_shutdown(SSL *s)
+{
+ int ret;
+#ifndef OPENSSL_NO_SCTP
+ BIO *wbio;
+
+ wbio = SSL_get_wbio(s);
+ if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
+ !(s->shutdown & SSL_SENT_SHUTDOWN)) {
+ ret = BIO_dgram_sctp_wait_for_dry(wbio);
+ if (ret < 0)
+ return -1;
+
+ if (ret == 0)
+ BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
+ NULL);
+ }
+#endif
+ ret = ssl3_shutdown(s);
+#ifndef OPENSSL_NO_SCTP
+ BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
+#endif
+ return ret;
+}
+
+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,
+ (long)s->d1->mtu, NULL);
+ }
+ } else
+ return 0;
+ }
+ return 1;
+}
+
+static size_t dtls1_link_min_mtu(void)
+{
+ return (g_probable_mtu[(sizeof(g_probable_mtu) /
+ sizeof(g_probable_mtu[0])) - 1]);
+}
+
+size_t dtls1_min_mtu(SSL *s)
+{
+ return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
+}
+
+size_t DTLS_get_data_mtu(const SSL *s)
+{
+ size_t mac_overhead, int_overhead, blocksize, ext_overhead;
+ const SSL_CIPHER *ciph = SSL_get_current_cipher(s);
+ size_t mtu = s->d1->mtu;
+
+ if (ciph == NULL)
+ return 0;
+
+ if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead,
+ &blocksize, &ext_overhead))
+ return 0;
+
+ if (SSL_READ_ETM(s))
+ ext_overhead += mac_overhead;
+ else
+ int_overhead += mac_overhead;
+
+ /* Subtract external overhead (e.g. IV/nonce, separate MAC) */
+ if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu)
+ return 0;
+ mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH;
+
+ /* Round encrypted payload down to cipher block size (for CBC etc.)
+ * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */
+ if (blocksize)
+ mtu -= (mtu % blocksize);
+
+ /* Subtract internal overhead (e.g. CBC padding len byte) */
+ if (int_overhead >= mtu)
+ return 0;
+ mtu -= int_overhead;
+
+ return mtu;
+}