text: /*
   * DTLS implementation written by Nagendra Modadugu
   * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
   */
  /* ====================================================================
   * Copyright (c) 1999-2005 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    openssl-core@OpenSSL.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com). */
  
  #include <openssl/base.h>
  
  #include <limits.h>
  #include <stdio.h>
  
  #if defined(OPENSSL_WINDOWS)
  #include <sys/timeb.h>
  #else
  #include <sys/socket.h>
  #include <sys/time.h>
  #endif
  
  #include <openssl/err.h>
  #include <openssl/mem.h>
  #include <openssl/obj.h>
  
  #include "ssl_locl.h"
  
  /* DTLS1_MTU_TIMEOUTS is the maximum number of timeouts to expire
   * before starting to decrease the MTU. */
  #define DTLS1_MTU_TIMEOUTS                     2
  
  /* DTLS1_MAX_TIMEOUTS is the maximum number of timeouts to expire
   * before failing the DTLS handshake. */
  #define DTLS1_MAX_TIMEOUTS                     12
  
  static void get_current_time(SSL *ssl, OPENSSL_timeval *out_clock);
  static OPENSSL_timeval *dtls1_get_timeout(SSL *s, OPENSSL_timeval *timeleft);
  
  int dtls1_new(SSL *s) {
    DTLS1_STATE *d1;
  
    if (!ssl3_new(s)) {
      return 0;
    }
    d1 = OPENSSL_malloc(sizeof *d1);
    if (d1 == NULL) {
      ssl3_free(s);
      return 0;
    }
    memset(d1, 0, sizeof *d1);
  
    d1->unprocessed_rcds.q = pqueue_new();
    d1->processed_rcds.q = pqueue_new();
    d1->buffered_messages = pqueue_new();
    d1->sent_messages = pqueue_new();
    d1->buffered_app_data.q = pqueue_new();
  
    if (!d1->unprocessed_rcds.q || !d1->processed_rcds.q ||
        !d1->buffered_messages || !d1->sent_messages ||
        !d1->buffered_app_data.q) {
      if (d1->unprocessed_rcds.q) {
        pqueue_free(d1->unprocessed_rcds.q);
      }
      if (d1->processed_rcds.q) {
        pqueue_free(d1->processed_rcds.q);
      }
      if (d1->buffered_messages) {
        pqueue_free(d1->buffered_messages);
      }
      if (d1->sent_messages) {
        pqueue_free(d1->sent_messages);
      }
      if (d1->buffered_app_data.q) {
        pqueue_free(d1->buffered_app_data.q);
      }
      OPENSSL_free(d1);
      ssl3_free(s);
      return 0;
    }
  
    s->d1 = d1;
  
    /* Set the version to the highest version for DTLS. This controls the initial
     * state of |s->enc_method| and what the API reports as the version prior to
     * negotiation.
     *
     * TODO(davidben): This is fragile and confusing. */
    s->version = DTLS1_2_VERSION;
    return 1;
  }
  
  static void dtls1_clear_queues(SSL *s) {
    pitem *item = NULL;
    hm_fragment *frag = NULL;
    DTLS1_RECORD_DATA *rdata;
  
    while ((item = pqueue_pop(s->d1->unprocessed_rcds.q)) != NULL) {
      rdata = (DTLS1_RECORD_DATA *)item->data;
      if (rdata->rbuf.buf) {
        OPENSSL_free(rdata->rbuf.buf);
      }
      OPENSSL_free(item->data);
      pitem_free(item);
    }
  
    while ((item = pqueue_pop(s->d1->processed_rcds.q)) != NULL) {
      rdata = (DTLS1_RECORD_DATA *)item->data;
      if (rdata->rbuf.buf) {
        OPENSSL_free(rdata->rbuf.buf);
      }
      OPENSSL_free(item->data);
      pitem_free(item);
    }
  
    while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
      frag = (hm_fragment *)item->data;
      dtls1_hm_fragment_free(frag);
      pitem_free(item);
    }
  
    while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
      frag = (hm_fragment *)item->data;
      dtls1_hm_fragment_free(frag);
      pitem_free(item);
    }
  
    while ((item = pqueue_pop(s->d1->buffered_app_data.q)) != NULL) {
      rdata = (DTLS1_RECORD_DATA *)item->data;
      if (rdata->rbuf.buf) {
        OPENSSL_free(rdata->rbuf.buf);
      }
      OPENSSL_free(item->data);
      pitem_free(item);
    }
  }
  
  void dtls1_free(SSL *s) {
    ssl3_free(s);
  
    if (s == NULL || s->d1 == NULL) {
      return;
    }
  
    dtls1_clear_queues(s);
  
    pqueue_free(s->d1->unprocessed_rcds.q);
    pqueue_free(s->d1->processed_rcds.q);
    pqueue_free(s->d1->buffered_messages);
    pqueue_free(s->d1->sent_messages);
    pqueue_free(s->d1->buffered_app_data.q);
  
    OPENSSL_free(s->d1);
    s->d1 = NULL;
  }
  
  long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg) {
    int ret = 0;
  
    switch (cmd) {
      case DTLS_CTRL_GET_TIMEOUT:
        if (dtls1_get_timeout(s, (OPENSSL_timeval *)parg) != NULL) {
          ret = 1;
        }
        break;
  
      case DTLS_CTRL_HANDLE_TIMEOUT:
        ret = dtls1_handle_timeout(s);
        break;
  
      default:
        ret = ssl3_ctrl(s, cmd, larg, parg);
        break;
    }
  
    return ret;
  }
  
  const SSL_CIPHER *dtls1_get_cipher(unsigned int u) {
    const SSL_CIPHER *ciph = ssl3_get_cipher(u);
    /* DTLS does not support stream ciphers. */
    if (ciph == NULL || ciph->algorithm_enc == SSL_RC4) {
      return NULL;
    }
  
    return ciph;
  }
  
  void dtls1_start_timer(SSL *s) {
    /* If timer is not set, initialize duration with 1 second */
    if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
      s->d1->timeout_duration = 1;
    }
  
    /* Set timeout to current time */
    get_current_time(s, &s->d1->next_timeout);
  
    /* Add duration to current time */
    s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
    BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
             &s->d1->next_timeout);
  }
  
  static OPENSSL_timeval *dtls1_get_timeout(SSL *s, OPENSSL_timeval *timeleft) {
    OPENSSL_timeval timenow;
  
    /* If no timeout is set, just return NULL */
    if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
      return NULL;
    }
  
    /* Get current time */
    get_current_time(s, &timenow);
  
    /* If timer already expired, set remaining time to 0 */
    if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
        (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
         s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
      memset(timeleft, 0, sizeof(OPENSSL_timeval));
      return timeleft;
    }
  
    /* Calculate time left until timer expires */
    memcpy(timeleft, &s->d1->next_timeout, sizeof(OPENSSL_timeval));
    timeleft->tv_sec -= timenow.tv_sec;
    timeleft->tv_usec -= timenow.tv_usec;
    if (timeleft->tv_usec < 0) {
      timeleft->tv_sec--;
      timeleft->tv_usec += 1000000;
    }
  
    /* If remaining time is less than 15 ms, set it to 0 to prevent issues
     * because of small devergences with socket timeouts. */
    if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
      memset(timeleft, 0, sizeof(OPENSSL_timeval));
    }
  
    return timeleft;
  }
  
  int dtls1_is_timer_expired(SSL *s) {
    OPENSSL_timeval timeleft;
  
    /* Get time left until timeout, return false if no timer running */
    if (dtls1_get_timeout(s, &timeleft) == NULL) {
      return 0;
    }
  
    /* Return false if timer is not expired yet */
    if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
      return 0;
    }
  
    /* Timer expired, so return true */
    return 1;
  }
  
  void dtls1_double_timeout(SSL *s) {
    s->d1->timeout_duration *= 2;
    if (s->d1->timeout_duration > 60) {
      s->d1->timeout_duration = 60;
    }
    dtls1_start_timer(s);
  }
  
  void dtls1_stop_timer(SSL *s) {
    /* Reset everything */
    s->d1->num_timeouts = 0;
    memset(&s->d1->next_timeout, 0, sizeof(OPENSSL_timeval));
    s->d1->timeout_duration = 1;
    BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
             &s->d1->next_timeout);
    /* Clear retransmission buffer */
    dtls1_clear_record_buffer(s);
  }
  
  int dtls1_check_timeout_num(SSL *s) {
    s->d1->num_timeouts++;
  
    /* Reduce MTU after 2 unsuccessful retransmissions */
    if (s->d1->num_timeouts > DTLS1_MTU_TIMEOUTS &&
        !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
      long mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0,
                          NULL);
      if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) {
        s->d1->mtu = (unsigned)mtu;
      }
    }
  
    if (s->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) {
      /* fail the connection, enough alerts have been sent */
      OPENSSL_PUT_ERROR(SSL, dtls1_check_timeout_num, SSL_R_READ_TIMEOUT_EXPIRED);
      return -1;
    }
  
    return 0;
  }
  
  int dtls1_handle_timeout(SSL *s) {
    /* if no timer is expired, don't do anything */
    if (!dtls1_is_timer_expired(s)) {
      return 0;
    }
  
    dtls1_double_timeout(s);
  
    if (dtls1_check_timeout_num(s) < 0) {
      return -1;
    }
  
    dtls1_start_timer(s);
    return dtls1_retransmit_buffered_messages(s);
  }
  
  static void get_current_time(SSL *ssl, OPENSSL_timeval *out_clock) {
    if (ssl->ctx->current_time_cb != NULL) {
      ssl->ctx->current_time_cb(ssl, out_clock);
      return;
    }
  
  #if defined(OPENSSL_WINDOWS)
    struct _timeb time;
    _ftime(&time);
    out_clock->tv_sec = time.time;
    out_clock->tv_usec = time.millitm * 1000;
  #else
    gettimeofday(out_clock, NULL);
  #endif
  }
  
  int dtls1_set_handshake_header(SSL *s, int htype, unsigned long len) {
    uint8_t *message = (uint8_t *)s->init_buf->data;
    const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
    uint8_t serialised_header[DTLS1_HM_HEADER_LENGTH];
    uint8_t *p = serialised_header;
  
    s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
    s->d1->next_handshake_write_seq++;
  
    dtls1_set_message_header(s, htype, len, s->d1->handshake_write_seq, 0, len);
    s->init_num = (int)len + DTLS1_HM_HEADER_LENGTH;
    s->init_off = 0;
  
    /* Buffer the message to handle re-xmits */
    dtls1_buffer_message(s, 0);
  
    /* Add the new message to the handshake hash. Serialize the message
     * header as if it were a single fragment. */
    *p++ = msg_hdr->type;
    l2n3(msg_hdr->msg_len, p);
    s2n(msg_hdr->seq, p);
    l2n3(0, p);
    l2n3(msg_hdr->msg_len, p);
    return ssl3_finish_mac(s, serialised_header, sizeof(serialised_header)) &&
           ssl3_finish_mac(s, message + DTLS1_HM_HEADER_LENGTH, len);
  }
  
  int dtls1_handshake_write(SSL *s) {
    return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
  }
  