Don't calculate the Finished MAC twice
[openssl.git] / ssl / statem / statem_dtls.c
index e13ed8d247e933f3b086b38d989ac459a88705a7..0ac60cbf995cc8850b3987f5e56a3b169672527d 100644 (file)
-/* ssl/statem/statem_dtls.c */
 /*
- * DTLS implementation written by Nagendra Modadugu
- * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
- */
-/* ====================================================================
- * Copyright (c) 1998-2005 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).
+ * Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
  *
- */
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
- *
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * The implementation was written so as to conform with Netscapes SSL.
- *
- * This library is free for commercial and non-commercial use as long as
- * the following conditions are aheared to.  The following conditions
- * apply to all code found in this distribution, be it the RC4, RSA,
- * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
- * included with this distribution is covered by the same copyright terms
- * except that the holder is Tim Hudson (tjh@cryptsoft.com).
- *
- * Copyright remains Eric Young's, and as such any Copyright notices in
- * the code are not to be removed.
- * If this package is used in a product, Eric Young should be given attribution
- * as the author of the parts of the library used.
- * This can be in the form of a textual message at program startup or
- * in documentation (online or textual) provided with the package.
- *
- * 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 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 acknowledgement:
- *    "This product includes cryptographic software written by
- *     Eric Young (eay@cryptsoft.com)"
- *    The word 'cryptographic' can be left out if the rouines from the library
- *    being used are not cryptographic related :-).
- * 4. If you include any Windows specific code (or a derivative thereof) from
- *    the apps directory (application code) you must include an acknowledgement:
- *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
- *
- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
- * ANY EXPRESS 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 AUTHOR OR 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.
- *
- * The licence and distribution terms for any publically available version or
- * derivative of this code cannot be changed.  i.e. this code cannot simply be
- * copied and put under another distribution licence
- * [including the GNU Public Licence.]
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
  */
 
 #include <limits.h>
 #include <string.h>
 #include <stdio.h>
 #include "../ssl_locl.h"
+#include "statem_locl.h"
+#include "internal/cryptlib.h"
 #include <openssl/buffer.h>
-#include <openssl/rand.h>
 #include <openssl/objects.h>
 #include <openssl/evp.h>
 #include <openssl/x509.h>
 
 #define RSMBLY_BITMASK_IS_COMPLETE(bitmask, msg_len, is_complete) { \
                         long ii; \
-                        OPENSSL_assert((msg_len) > 0); \
                         is_complete = 1; \
                         if (bitmask[(((msg_len) - 1) >> 3)] != bitmask_end_values[((msg_len) & 7)]) is_complete = 0; \
                         if (is_complete) for (ii = (((msg_len) - 1) >> 3) - 1; ii >= 0 ; ii--) \
@@ -149,18 +43,17 @@ static unsigned char bitmask_start_values[] =
 static unsigned char bitmask_end_values[] =
     { 0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f };
 
-static void dtls1_fix_message_header(SSL *s, unsigned long frag_off,
-                                     unsigned long frag_len);
+static void dtls1_fix_message_header(SSL *s, size_t frag_off,
+                                     size_t frag_len);
 static unsigned char *dtls1_write_message_header(SSL *s, unsigned char *p);
 static void dtls1_set_message_header_int(SSL *s, unsigned char mt,
-                                         unsigned long len,
+                                         size_t len,
                                          unsigned short seq_num,
-                                         unsigned long frag_off,
-                                         unsigned long frag_len);
-static int dtls_get_reassembled_message(SSL *s, long *len);
+                                         size_t frag_off,
+                                         size_t frag_len);
+static int dtls_get_reassembled_message(SSL *s, int *errtype, size_t *len);
 
-static hm_fragment *dtls1_hm_fragment_new(unsigned long frag_len,
-                                          int reassembly)
+static hm_fragment *dtls1_hm_fragment_new(size_t frag_len, int reassembly)
 {
     hm_fragment *frag = NULL;
     unsigned char *buf = NULL;
@@ -203,8 +96,7 @@ void dtls1_hm_fragment_free(hm_fragment *frag)
     if (frag->msg_header.is_ccs) {
         EVP_CIPHER_CTX_free(frag->msg_header.
                             saved_retransmit_state.enc_write_ctx);
-        EVP_MD_CTX_destroy(frag->msg_header.
-                           saved_retransmit_state.write_hash);
+        EVP_MD_CTX_free(frag->msg_header.saved_retransmit_state.write_hash);
     }
     OPENSSL_free(frag->fragment);
     OPENSSL_free(frag->reassembly);
@@ -218,25 +110,28 @@ void dtls1_hm_fragment_free(hm_fragment *frag)
 int dtls1_do_write(SSL *s, int type)
 {
     int ret;
-    unsigned int curr_mtu;
+    size_t written;
+    size_t curr_mtu;
     int retry = 1;
-    unsigned int len, frag_off, mac_size, blocksize, used_len;
+    size_t len, frag_off, mac_size, blocksize, used_len;
 
     if (!dtls1_query_mtu(s))
         return -1;
 
-    OPENSSL_assert(s->d1->mtu >= dtls1_min_mtu(s)); /* should have something
-                                                     * reasonable now */
+    if (s->d1->mtu < dtls1_min_mtu(s))
+        /* should have something reasonable now */
+        return -1;
 
-    if (s->init_off == 0 && type == SSL3_RT_HANDSHAKE)
-        OPENSSL_assert(s->init_num ==
-                       (int)s->d1->w_msg_hdr.msg_len +
-                       DTLS1_HM_HEADER_LENGTH);
+    if (s->init_off == 0 && type == SSL3_RT_HANDSHAKE) {
+        if (!ossl_assert(s->init_num ==
+                         s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH))
+            return -1;
+    }
 
     if (s->write_hash) {
         if (s->enc_write_ctx
-            && ((EVP_CIPHER_CTX_mode(s->enc_write_ctx) == EVP_CIPH_GCM_MODE) ||
-                (EVP_CIPHER_CTX_mode(s->enc_write_ctx) == EVP_CIPH_CCM_MODE)))
+            && (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_write_ctx)) &
+                EVP_CIPH_FLAG_AEAD_CIPHER) != 0)
             mac_size = 0;
         else
             mac_size = EVP_MD_CTX_size(s->write_hash);
@@ -245,14 +140,50 @@ int dtls1_do_write(SSL *s, int type)
 
     if (s->enc_write_ctx &&
         (EVP_CIPHER_CTX_mode(s->enc_write_ctx) == EVP_CIPH_CBC_MODE))
-        blocksize = 2 * EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
+        blocksize = 2 * EVP_CIPHER_CTX_block_size(s->enc_write_ctx);
     else
         blocksize = 0;
 
     frag_off = 0;
+    s->rwstate = SSL_NOTHING;
+
     /* s->init_num shouldn't ever be < 0...but just in case */
     while (s->init_num > 0) {
-        used_len = BIO_wpending(SSL_get_wbio(s)) + DTLS1_RT_HEADER_LENGTH
+        if (type == SSL3_RT_HANDSHAKE && s->init_off != 0) {
+            /* We must be writing a fragment other than the first one */
+
+            if (frag_off > 0) {
+                /* This is the first attempt at writing out this fragment */
+
+                if (s->init_off <= DTLS1_HM_HEADER_LENGTH) {
+                    /*
+                     * Each fragment that was already sent must at least have
+                     * contained the message header plus one other byte.
+                     * Therefore |init_off| must have progressed by at least
+                     * |DTLS1_HM_HEADER_LENGTH + 1| bytes. If not something went
+                     * wrong.
+                     */
+                    return -1;
+                }
+
+                /*
+                 * Adjust |init_off| and |init_num| to allow room for a new
+                 * message header for this fragment.
+                 */
+                s->init_off -= DTLS1_HM_HEADER_LENGTH;
+                s->init_num += DTLS1_HM_HEADER_LENGTH;
+            } else {
+                /*
+                 * We must have been called again after a retry so use the
+                 * fragment offset from our last attempt. We do not need
+                 * to adjust |init_off| and |init_num| as above, because
+                 * that should already have been done before the retry.
+                 */
+                frag_off = s->d1->w_msg_hdr.frag_off;
+            }
+        }
+
+        used_len = BIO_wpending(s->wbio) + DTLS1_RT_HEADER_LENGTH
             + mac_size + blocksize;
         if (s->d1->mtu > used_len)
             curr_mtu = s->d1->mtu - used_len;
@@ -263,9 +194,11 @@ int dtls1_do_write(SSL *s, int type)
             /*
              * grr.. we could get an error if MTU picked was wrong
              */
-            ret = BIO_flush(SSL_get_wbio(s));
-            if (ret <= 0)
+            ret = BIO_flush(s->wbio);
+            if (ret <= 0) {
+                s->rwstate = SSL_WRITING;
                 return ret;
+            }
             used_len = DTLS1_RT_HEADER_LENGTH + mac_size + blocksize;
             if (s->d1->mtu > used_len + DTLS1_HM_HEADER_LENGTH) {
                 curr_mtu = s->d1->mtu - used_len;
@@ -283,33 +216,13 @@ int dtls1_do_write(SSL *s, int type)
         else
             len = s->init_num;
 
-        /* Shouldn't ever happen */
-        if (len > INT_MAX)
-            len = INT_MAX;
+        if (len > s->max_send_fragment)
+            len = s->max_send_fragment;
 
         /*
          * XDTLS: this function is too long.  split out the CCS part
          */
         if (type == SSL3_RT_HANDSHAKE) {
-            if (s->init_off != 0) {
-                OPENSSL_assert(s->init_off > DTLS1_HM_HEADER_LENGTH);
-                s->init_off -= DTLS1_HM_HEADER_LENGTH;
-                s->init_num += DTLS1_HM_HEADER_LENGTH;
-
-                /*
-                 * We just checked that s->init_num > 0 so this cast should
-                 * be safe
-                 */
-                if (((unsigned int)s->init_num) > curr_mtu)
-                    len = curr_mtu;
-                else
-                    len = s->init_num;
-            }
-
-            /* Shouldn't ever happen */
-            if (len > INT_MAX)
-                len = INT_MAX;
-
             if (len < DTLS1_HM_HEADER_LENGTH) {
                 /*
                  * len is so small that we really can't do anything sensible
@@ -317,16 +230,15 @@ int dtls1_do_write(SSL *s, int type)
                  */
                 return -1;
             }
-            dtls1_fix_message_header(s, frag_off,
-                                     len - DTLS1_HM_HEADER_LENGTH);
+            dtls1_fix_message_header(s, frag_off, len - DTLS1_HM_HEADER_LENGTH);
 
             dtls1_write_message_header(s,
                                        (unsigned char *)&s->init_buf->
                                        data[s->init_off]);
         }
 
-        ret = dtls1_write_bytes(s, type, &s->init_buf->data[s->init_off],
-                                len);
+        ret = dtls1_write_bytes(s, type, &s->init_buf->data[s->init_off], len,
+                                &written);
         if (ret < 0) {
             /*
              * might need to update MTU here, but we don't know which
@@ -344,7 +256,7 @@ int dtls1_do_write(SSL *s, int type)
                 } else
                     return -1;
             } else {
-                return (-1);
+                return -1;
             }
         } else {
 
@@ -352,7 +264,8 @@ int dtls1_do_write(SSL *s, int type)
              * bad if this assert fails, only part of the handshake message
              * got sent.  but why would this happen?
              */
-            OPENSSL_assert(len == (unsigned int)ret);
+            if (!ossl_assert(len == written))
+                return -1;
 
             if (type == SSL3_RT_HANDSHAKE && !s->d1->retransmitting) {
                 /*
@@ -362,7 +275,7 @@ int dtls1_do_write(SSL *s, int type)
                 unsigned char *p =
                     (unsigned char *)&s->init_buf->data[s->init_off];
                 const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
-                int xlen;
+                size_t xlen;
 
                 if (frag_off == 0 && s->version != DTLS1_BAD_VER) {
                     /*
@@ -375,16 +288,17 @@ int dtls1_do_write(SSL *s, int type)
                     l2n3(0, p);
                     l2n3(msg_hdr->msg_len, p);
                     p -= DTLS1_HM_HEADER_LENGTH;
-                    xlen = ret;
+                    xlen = written;
                 } else {
                     p += DTLS1_HM_HEADER_LENGTH;
-                    xlen = ret - DTLS1_HM_HEADER_LENGTH;
+                    xlen = written - DTLS1_HM_HEADER_LENGTH;
                 }
 
-                ssl3_finish_mac(s, p, xlen);
+                if (!ssl3_finish_mac(s, p, xlen))
+                    return -1;
             }
 
-            if (ret == s->init_num) {
+            if (written == s->init_num) {
                 if (s->msg_callback)
                     s->msg_callback(1, s->version, type, s->init_buf->data,
                                     (size_t)(s->init_off + s->init_num), s,
@@ -393,40 +307,50 @@ int dtls1_do_write(SSL *s, int type)
                 s->init_off = 0; /* done writing this message */
                 s->init_num = 0;
 
-                return (1);
+                return 1;
             }
-            s->init_off += ret;
-            s->init_num -= ret;
-            frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
+            s->init_off += written;
+            s->init_num -= written;
+            written -= DTLS1_HM_HEADER_LENGTH;
+            frag_off += written;
+
+            /*
+             * We save the fragment offset for the next fragment so we have it
+             * available in case of an IO retry. We don't know the length of the
+             * next fragment yet so just set that to 0 for now. It will be
+             * updated again later.
+             */
+            dtls1_fix_message_header(s, frag_off, 0);
         }
     }
-    return (0);
+    return 0;
 }
 
-int dtls_get_message(SSL *s, int *mt, unsigned long *len)
+int dtls_get_message(SSL *s, int *mt, size_t *len)
 {
     struct hm_header_st *msg_hdr;
     unsigned char *p;
-    unsigned long msg_len;
-    int ok;
-    long tmplen;
+    size_t msg_len;
+    size_t tmplen;
+    int errtype;
 
     msg_hdr = &s->d1->r_msg_hdr;
     memset(msg_hdr, 0, sizeof(*msg_hdr));
 
  again:
-    ok = dtls_get_reassembled_message(s, &tmplen);
-    if (tmplen == DTLS1_HM_BAD_FRAGMENT
-        || tmplen == DTLS1_HM_FRAGMENT_RETRY) {
-        /* bad fragment received */
-        goto again;
-    } else if (tmplen <= 0 && !ok) {
+    if (!dtls_get_reassembled_message(s, &errtype, &tmplen)) {
+        if (errtype == DTLS1_HM_BAD_FRAGMENT
+                || errtype == DTLS1_HM_FRAGMENT_RETRY) {
+            /* bad fragment received */
+            goto again;
+        }
         return 0;
     }
 
     *mt = s->s3->tmp.message_type;
 
     p = (unsigned char *)s->init_buf->data;
+    *len = s->init_num;
 
     if (*mt == SSL3_MT_CHANGE_CIPHER_SPEC) {
         if (s->msg_callback) {
@@ -436,7 +360,6 @@ int dtls_get_message(SSL *s, int *mt, unsigned long *len)
         /*
          * This isn't a real handshake message so skip the processing below.
          */
-        *len = (unsigned long)tmplen;
         return 1;
     }
 
@@ -453,7 +376,17 @@ int dtls_get_message(SSL *s, int *mt, unsigned long *len)
         msg_len += DTLS1_HM_HEADER_LENGTH;
     }
 
-    ssl3_finish_mac(s, p, msg_len);
+    /*
+     * If receiving Finished, record MAC of prior handshake messages for
+     * Finished verification.
+     */
+    if (*mt == SSL3_MT_FINISHED && !ssl3_take_mac(s)) {
+        /* SSLfatal() already called */
+        return 0;
+    }
+
+    if (!ssl3_finish_mac(s, p, msg_len))
+        return 0;
     if (s->msg_callback)
         s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
                         p, msg_len, s, s->msg_callback_arg);
@@ -462,13 +395,24 @@ int dtls_get_message(SSL *s, int *mt, unsigned long *len)
 
     s->d1->handshake_read_seq++;
 
-
     s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
-    *len = s->init_num;
 
     return 1;
 }
 
+/*
+ * dtls1_max_handshake_message_len returns the maximum number of bytes
+ * permitted in a DTLS handshake message for |s|. The minimum is 16KB, but
+ * may be greater if the maximum certificate list size requires it.
+ */
+static size_t dtls1_max_handshake_message_len(const SSL *s)
+{
+    size_t max_len = DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;
+    if (max_len < s->max_cert_list)
+        return s->max_cert_list;
+    return max_len;
+}
+
 static int dtls1_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr)
 {
     size_t frag_off, frag_len, msg_len;
@@ -478,20 +422,22 @@ static int dtls1_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr)
     frag_len = msg_hdr->frag_len;
 
     /* sanity checking */
-    if ((frag_off + frag_len) > msg_len) {
-        SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT, SSL_R_EXCESSIVE_MESSAGE_SIZE);
-        return SSL_AD_ILLEGAL_PARAMETER;
+    if ((frag_off + frag_len) > msg_len
+            || msg_len > dtls1_max_handshake_message_len(s)) {
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_DTLS1_PREPROCESS_FRAGMENT,
+                 SSL_R_EXCESSIVE_MESSAGE_SIZE);
+        return 0;
     }
 
     if (s->d1->r_msg_hdr.frag_off == 0) { /* first fragment */
         /*
-         * msg_len is limited to 2^24, but is effectively checked against max
-         * above
+         * msg_len is limited to 2^24, but is effectively checked against
+         * dtls_max_handshake_message_len(s) above
          */
-        if (!BUF_MEM_grow_clean
-            (s->init_buf, msg_len + DTLS1_HM_HEADER_LENGTH)) {
-            SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT, ERR_R_BUF_LIB);
-            return SSL_AD_INTERNAL_ERROR;
+        if (!BUF_MEM_grow_clean(s->init_buf, msg_len + DTLS1_HM_HEADER_LENGTH)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PREPROCESS_FRAGMENT,
+                     ERR_R_BUF_LIB);
+            return 0;
         }
 
         s->s3->tmp.message_size = msg_len;
@@ -504,14 +450,19 @@ static int dtls1_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr)
          * They must be playing with us! BTW, failure to enforce upper limit
          * would open possibility for buffer overrun.
          */
-        SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT, SSL_R_EXCESSIVE_MESSAGE_SIZE);
-        return SSL_AD_ILLEGAL_PARAMETER;
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_DTLS1_PREPROCESS_FRAGMENT,
+                 SSL_R_EXCESSIVE_MESSAGE_SIZE);
+        return 0;
     }
 
-    return 0;                   /* no error */
+    return 1;
 }
 
-static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
+/*
+ * Returns 1 if there is a buffered fragment available, 0 if not, or -1 on a
+ * fatal error.
+ */
+static int dtls1_retrieve_buffered_fragment(SSL *s, size_t *len)
 {
     /*-
      * (0) check whether the desired fragment is available
@@ -521,26 +472,37 @@ static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
      */
     pitem *item;
     hm_fragment *frag;
-    int al;
+    int ret;
 
-    *ok = 0;
-    item = pqueue_peek(s->d1->buffered_messages);
-    if (item == NULL)
-        return 0;
+    do {
+        item = pqueue_peek(s->d1->buffered_messages);
+        if (item == NULL)
+            return 0;
 
-    frag = (hm_fragment *)item->data;
+        frag = (hm_fragment *)item->data;
+
+        if (frag->msg_header.seq < s->d1->handshake_read_seq) {
+            /* This is a stale message that has been buffered so clear it */
+            pqueue_pop(s->d1->buffered_messages);
+            dtls1_hm_fragment_free(frag);
+            pitem_free(item);
+            item = NULL;
+            frag = NULL;
+        }
+    } while (item == NULL);
 
     /* Don't return if reassembly still in progress */
     if (frag->reassembly != NULL)
         return 0;
 
     if (s->d1->handshake_read_seq == frag->msg_header.seq) {
-        unsigned long frag_len = frag->msg_header.frag_len;
+        size_t frag_len = frag->msg_header.frag_len;
         pqueue_pop(s->d1->buffered_messages);
 
-        al = dtls1_preprocess_fragment(s, &frag->msg_header);
+        /* Calls SSLfatal() as required */
+        ret = dtls1_preprocess_fragment(s, &frag->msg_header);
 
-        if (al == 0) {          /* no alert */
+        if (ret) {
             unsigned char *p =
                 (unsigned char *)s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
             memcpy(&p[frag->msg_header.frag_off], frag->fragment,
@@ -550,48 +512,36 @@ static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
         dtls1_hm_fragment_free(frag);
         pitem_free(item);
 
-        if (al == 0) {
-            *ok = 1;
-            return frag_len;
+        if (ret) {
+            *len = frag_len;
+            return 1;
         }
 
-        ssl3_send_alert(s, SSL3_AL_FATAL, al);
+        /* Fatal error */
         s->init_num = 0;
-        *ok = 0;
         return -1;
-    } else
+    } else {
         return 0;
-}
-
-/*
- * dtls1_max_handshake_message_len returns the maximum number of bytes
- * permitted in a DTLS handshake message for |s|. The minimum is 16KB, but
- * may be greater if the maximum certificate list size requires it.
- */
-static unsigned long dtls1_max_handshake_message_len(const SSL *s)
-{
-    unsigned long max_len =
-        DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;
-    if (max_len < (unsigned long)s->max_cert_list)
-        return s->max_cert_list;
-    return max_len;
+    }
 }
 
 static int
-dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
+dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr)
 {
     hm_fragment *frag = NULL;
     pitem *item = NULL;
     int i = -1, is_complete;
     unsigned char seq64be[8];
-    unsigned long frag_len = msg_hdr->frag_len;
+    size_t frag_len = msg_hdr->frag_len;
+    size_t readbytes;
 
     if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len ||
         msg_hdr->msg_len > dtls1_max_handshake_message_len(s))
         goto err;
 
-    if (frag_len == 0)
+    if (frag_len == 0) {
         return DTLS1_HM_FRAGMENT_RETRY;
+    }
 
     /* Try to find item in queue */
     memset(seq64be, 0, sizeof(seq64be));
@@ -628,10 +578,10 @@ dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
                                           devnull,
                                           frag_len >
                                           sizeof(devnull) ? sizeof(devnull) :
-                                          frag_len, 0);
+                                          frag_len, 0, &readbytes);
             if (i <= 0)
                 goto err;
-            frag_len -= i;
+            frag_len -= readbytes;
         }
         return DTLS1_HM_FRAGMENT_RETRY;
     }
@@ -639,8 +589,8 @@ dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
     /* read the body of the fragment (header has already been read */
     i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
                                   frag->fragment + msg_hdr->frag_off,
-                                  frag_len, 0);
-    if ((unsigned long)i != frag_len)
+                                  frag_len, 0, &readbytes);
+    if (i <= 0 || readbytes != frag_len)
         i = -1;
     if (i <= 0)
         goto err;
@@ -648,6 +598,8 @@ dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
     RSMBLY_BITMASK_MARK(frag->reassembly, (long)msg_hdr->frag_off,
                         (long)(msg_hdr->frag_off + frag_len));
 
+    if (!ossl_assert(msg_hdr->msg_len > 0))
+        goto err;
     RSMBLY_BITMASK_IS_COMPLETE(frag->reassembly, (long)msg_hdr->msg_len,
                                is_complete);
 
@@ -670,7 +622,8 @@ dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
          * would have returned it and control would never have reached this
          * branch.
          */
-        OPENSSL_assert(item != NULL);
+        if (!ossl_assert(item != NULL))
+            goto err;
     }
 
     return DTLS1_HM_FRAGMENT_RETRY;
@@ -678,19 +631,18 @@ dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
  err:
     if (item == NULL)
         dtls1_hm_fragment_free(frag);
-    *ok = 0;
-    return i;
+    return -1;
 }
 
 static int
-dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
-                                 int *ok)
+dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr)
 {
     int i = -1;
     hm_fragment *frag = NULL;
     pitem *item = NULL;
     unsigned char seq64be[8];
-    unsigned long frag_len = msg_hdr->frag_len;
+    size_t frag_len = msg_hdr->frag_len;
+    size_t readbytes;
 
     if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len)
         goto err;
@@ -715,8 +667,7 @@ dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
      */
     if (msg_hdr->seq <= s->d1->handshake_read_seq ||
         msg_hdr->seq > s->d1->handshake_read_seq + 10 || item != NULL ||
-        (s->d1->handshake_read_seq == 0 && msg_hdr->type == SSL3_MT_FINISHED))
-    {
+        (s->d1->handshake_read_seq == 0 && msg_hdr->type == SSL3_MT_FINISHED)) {
         unsigned char devnull[256];
 
         while (frag_len) {
@@ -724,14 +675,15 @@ dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
                                           devnull,
                                           frag_len >
                                           sizeof(devnull) ? sizeof(devnull) :
-                                          frag_len, 0);
+                                          frag_len, 0, &readbytes);
             if (i <= 0)
                 goto err;
-            frag_len -= i;
+            frag_len -= readbytes;
         }
     } else {
-        if (frag_len != msg_hdr->msg_len)
-            return dtls1_reassemble_fragment(s, msg_hdr, ok);
+        if (frag_len != msg_hdr->msg_len) {
+            return dtls1_reassemble_fragment(s, msg_hdr);
+        }
 
         if (frag_len > dtls1_max_handshake_message_len(s))
             goto err;
@@ -747,8 +699,9 @@ dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
              * read the body of the fragment (header has already been read
              */
             i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
-                                          frag->fragment, frag_len, 0);
-            if ((unsigned long)i != frag_len)
+                                          frag->fragment, frag_len, 0,
+                                          &readbytes);
+            if (i<=0 || readbytes != frag_len)
                 i = -1;
             if (i <= 0)
                 goto err;
@@ -767,7 +720,8 @@ dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
          * have been processed with |dtls1_reassemble_fragment|, above, or
          * the record will have been discarded.
          */
-        OPENSSL_assert(item != NULL);
+        if (!ossl_assert(item != NULL))
+            goto err;
     }
 
     return DTLS1_HM_FRAGMENT_RETRY;
@@ -775,56 +729,61 @@ dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
  err:
     if (item == NULL)
         dtls1_hm_fragment_free(frag);
-    *ok = 0;
-    return i;
+    return 0;
 }
 
-static int dtls_get_reassembled_message(SSL *s, long *len)
+static int dtls_get_reassembled_message(SSL *s, int *errtype, size_t *len)
 {
     unsigned char wire[DTLS1_HM_HEADER_LENGTH];
-    unsigned long mlen, frag_off, frag_len;
-    int i, al, recvd_type;
+    size_t mlen, frag_off, frag_len;
+    int i, ret, recvd_type;
     struct hm_header_st msg_hdr;
-    int ok;
+    size_t readbytes;
+
+    *errtype = 0;
 
  redo:
     /* see if we have the required fragment already */
-    if ((frag_len = dtls1_retrieve_buffered_fragment(s, &ok)) || ok) {
-        if (ok)
-            s->init_num = frag_len;
+    ret = dtls1_retrieve_buffered_fragment(s, &frag_len);
+    if (ret < 0) {
+        /* SSLfatal() already called */
+        return 0;
+    }
+    if (ret > 0) {
+        s->init_num = frag_len;
         *len = frag_len;
-        return ok;
+        return 1;
     }
 
     /* read handshake message header */
     i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, &recvd_type, wire,
-                                  DTLS1_HM_HEADER_LENGTH, 0);
+                                  DTLS1_HM_HEADER_LENGTH, 0, &readbytes);
     if (i <= 0) {               /* nbio, or an error */
         s->rwstate = SSL_READING;
-        *len = i;
+        *len = 0;
         return 0;
     }
-    if(recvd_type == SSL3_RT_CHANGE_CIPHER_SPEC) {
+    if (recvd_type == SSL3_RT_CHANGE_CIPHER_SPEC) {
         if (wire[0] != SSL3_MT_CCS) {
-            al = SSL_AD_UNEXPECTED_MESSAGE;
-            SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
-                   SSL_R_BAD_CHANGE_CIPHER_SPEC);
+            SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
+                     SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
+                     SSL_R_BAD_CHANGE_CIPHER_SPEC);
             goto f_err;
         }
 
-        memcpy(s->init_buf->data, wire, i);
-        s->init_num = i - 1;
+        memcpy(s->init_buf->data, wire, readbytes);
+        s->init_num = readbytes - 1;
         s->init_msg = s->init_buf->data + 1;
         s->s3->tmp.message_type = SSL3_MT_CHANGE_CIPHER_SPEC;
-        s->s3->tmp.message_size = i - 1;
-        *len = i - 1;
+        s->s3->tmp.message_size = readbytes - 1;
+        *len = readbytes - 1;
         return 1;
     }
 
     /* Handshake fails if message header is incomplete */
-    if (i != DTLS1_HM_HEADER_LENGTH) {
-        al = SSL_AD_UNEXPECTED_MESSAGE;
-        SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
+    if (readbytes != DTLS1_HM_HEADER_LENGTH) {
+        SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
+                 SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
         goto f_err;
     }
 
@@ -840,8 +799,8 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
      * Fragments must not span records.
      */
     if (frag_len > RECORD_LAYER_get_rrec_length(&s->rlayer)) {
-        al = SSL3_AD_ILLEGAL_PARAMETER;
-        SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
+                 SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
         goto f_err;
     }
 
@@ -852,17 +811,19 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
      * although we're still expecting seq 0 (ClientHello)
      */
     if (msg_hdr.seq != s->d1->handshake_read_seq) {
-        *len = dtls1_process_out_of_seq_message(s, &msg_hdr, &ok);
-        return ok;
+        *errtype = dtls1_process_out_of_seq_message(s, &msg_hdr);
+        return 0;
     }
 
     if (frag_len && frag_len < mlen) {
-        *len = dtls1_reassemble_fragment(s, &msg_hdr, &ok);
-        return ok;
+        *errtype = dtls1_reassemble_fragment(s, &msg_hdr);
+        return 0;
     }
 
-    if (!s->server && s->d1->r_msg_hdr.frag_off == 0 &&
-        wire[0] == SSL3_MT_HELLO_REQUEST) {
+    if (!s->server
+            && s->d1->r_msg_hdr.frag_off == 0
+            && s->statem.hand_state != TLS_ST_OK
+            && wire[0] == SSL3_MT_HELLO_REQUEST) {
         /*
          * The server may always send 'Hello Request' messages -- we are
          * doing a handshake anyway now, so ignore them if their format is
@@ -876,24 +837,26 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
 
             s->init_num = 0;
             goto redo;
-        } else {                /* Incorrectly formated Hello request */
+        } else {                /* Incorrectly formatted Hello request */
 
-            al = SSL_AD_UNEXPECTED_MESSAGE;
-            SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
-                   SSL_R_UNEXPECTED_MESSAGE);
+            SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
+                     SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
+                     SSL_R_UNEXPECTED_MESSAGE);
             goto f_err;
         }
     }
 
-    if ((al = dtls1_preprocess_fragment(s, &msg_hdr)))
+    if (!dtls1_preprocess_fragment(s, &msg_hdr)) {
+        /* SSLfatal() already called */
         goto f_err;
+    }
 
     if (frag_len > 0) {
         unsigned char *p =
             (unsigned char *)s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
 
         i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
-                                      &p[frag_off], frag_len, 0);
+                                      &p[frag_off], frag_len, 0, &readbytes);
 
         /*
          * This shouldn't ever fail due to NBIO because we already checked
@@ -901,19 +864,20 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
          */
         if (i <= 0) {
             s->rwstate = SSL_READING;
-            *len = i;
+            *len = 0;
             return 0;
         }
-    } else
-        i = 0;
+    } else {
+        readbytes = 0;
+    }
 
     /*
      * XDTLS: an incorrectly formatted fragment should cause the handshake
      * to fail
      */
-    if (i != (int)frag_len) {
-        al = SSL3_AD_ILLEGAL_PARAMETER;
-        SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL3_AD_ILLEGAL_PARAMETER);
+    if (readbytes != frag_len) {
+        SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
+                 SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
         goto f_err;
     }
 
@@ -927,9 +891,8 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
     return 1;
 
  f_err:
-    ssl3_send_alert(s, SSL3_AL_FATAL, al);
     s->init_num = 0;
-    *len = -1;
+    *len = 0;
     return 0;
 }
 
@@ -942,44 +905,34 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
  * ssl->session->read_compression       assign
  * ssl->session->read_hash              assign
  */
-int dtls_construct_change_cipher_spec(SSL *s)
+int dtls_construct_change_cipher_spec(SSL *s, WPACKET *pkt)
 {
-    unsigned char *p;
-
-    p = (unsigned char *)s->init_buf->data;
-    *p++ = SSL3_MT_CCS;
-    s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
-    s->init_num = DTLS1_CCS_HEADER_LENGTH;
-
     if (s->version == DTLS1_BAD_VER) {
         s->d1->next_handshake_write_seq++;
-        s2n(s->d1->handshake_write_seq, p);
-        s->init_num += 2;
-    }
-
-    s->init_off = 0;
 
-    dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
-                                 s->d1->handshake_write_seq, 0, 0);
-
-    /* buffer the message to handle re-xmits */
-    if (!dtls1_buffer_message(s, 1)) {
-        SSLerr(SSL_F_DTLS_CONSTRUCT_CHANGE_CIPHER_SPEC, ERR_R_INTERNAL_ERROR);
-        return 0;
+        if (!WPACKET_put_bytes_u16(pkt, s->d1->handshake_write_seq)) {
+            SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                     SSL_F_DTLS_CONSTRUCT_CHANGE_CIPHER_SPEC,
+                     ERR_R_INTERNAL_ERROR);
+            return 0;
+        }
     }
 
     return 1;
 }
 
 #ifndef OPENSSL_NO_SCTP
-enum WORK_STATE dtls_wait_for_dry(SSL *s)
+WORK_STATE dtls_wait_for_dry(SSL *s)
 {
     int ret;
 
     /* read app data until dry event */
     ret = BIO_dgram_sctp_wait_for_dry(SSL_get_wbio(s));
-    if (ret < 0)
+    if (ret < 0) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS_WAIT_FOR_DRY,
+                 ERR_R_INTERNAL_ERROR);
         return WORK_ERROR;
+    }
 
     if (ret == 0) {
         s->s3->in_read_app_data = 2;
@@ -995,24 +948,20 @@ enum WORK_STATE dtls_wait_for_dry(SSL *s)
 int dtls1_read_failed(SSL *s, int code)
 {
     if (code > 0) {
-        fprintf(stderr, "invalid state reached %s:%d", __FILE__, __LINE__);
-        return 1;
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR,
+                 SSL_F_DTLS1_READ_FAILED, ERR_R_INTERNAL_ERROR);
+        return 0;
     }
 
-    if (!dtls1_is_timer_expired(s)) {
+    if (!dtls1_is_timer_expired(s) || ossl_statem_in_error(s)) {
         /*
          * not a timeout, none of our business, let higher layers handle
          * this.  in fact it's probably an error
          */
         return code;
     }
-#ifndef OPENSSL_NO_HEARTBEATS
-    /* done, no need to send a retransmit */
-    if (!SSL_in_init(s) && !s->tlsext_hb_pending)
-#else
     /* done, no need to send a retransmit */
     if (!SSL_in_init(s))
-#endif
     {
         BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
         return code;
@@ -1038,7 +987,7 @@ int dtls1_get_queue_priority(unsigned short seq, int is_ccs)
 
 int dtls1_retransmit_buffered_messages(SSL *s)
 {
-    pqueue sent = s->d1->sent_messages;
+    pqueue *sent = s->d1->sent_messages;
     piterator iter;
     pitem *item;
     hm_fragment *frag;
@@ -1051,11 +1000,8 @@ int dtls1_retransmit_buffered_messages(SSL *s)
         if (dtls1_retransmit_message(s, (unsigned short)
                                      dtls1_get_queue_priority
                                      (frag->msg_header.seq,
-                                      frag->msg_header.is_ccs), 0,
-                                     &found) <= 0 && found) {
-            fprintf(stderr, "dtls1_retransmit_message() failed\n");
+                                      frag->msg_header.is_ccs), &found) <= 0)
             return -1;
-        }
     }
 
     return 1;
@@ -1071,22 +1017,26 @@ int dtls1_buffer_message(SSL *s, int is_ccs)
      * this function is called immediately after a message has been
      * serialized
      */
-    OPENSSL_assert(s->init_off == 0);
+    if (!ossl_assert(s->init_off == 0))
+        return 0;
 
     frag = dtls1_hm_fragment_new(s->init_num, 0);
-    if (!frag)
+    if (frag == NULL)
         return 0;
 
     memcpy(frag->fragment, s->init_buf->data, s->init_num);
 
     if (is_ccs) {
         /* For DTLS1_BAD_VER the header length is non-standard */
-        OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
-                       ((s->version==DTLS1_BAD_VER)?3:DTLS1_CCS_HEADER_LENGTH)
-                       == (unsigned int)s->init_num);
+        if (!ossl_assert(s->d1->w_msg_hdr.msg_len +
+                         ((s->version ==
+                           DTLS1_BAD_VER) ? 3 : DTLS1_CCS_HEADER_LENGTH)
+                         == (unsigned int)s->init_num))
+            return 0;
     } else {
-        OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
-                       DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num);
+        if (!ossl_assert(s->d1->w_msg_hdr.msg_len +
+                         DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num))
+            return 0;
     }
 
     frag->msg_header.msg_len = s->d1->w_msg_hdr.msg_len;
@@ -1124,9 +1074,7 @@ int dtls1_buffer_message(SSL *s, int is_ccs)
     return 1;
 }
 
-int
-dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
-                         int *found)
+int dtls1_retransmit_message(SSL *s, unsigned short seq, int *found)
 {
     int ret;
     /* XDTLS: for now assuming that read/writes are blocking */
@@ -1136,11 +1084,6 @@ dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
     unsigned char seq64be[8];
     struct dtls1_retransmit_state saved_state;
 
-    /*-
-      OPENSSL_assert(s->init_num == 0);
-      OPENSSL_assert(s->init_off == 0);
-     */
-
     /* XDTLS:  the requested message ought to be found, otherwise error */
     memset(seq64be, 0, sizeof(seq64be));
     seq64be[6] = (unsigned char)(seq >> 8);
@@ -1148,7 +1091,8 @@ dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
 
     item = pqueue_find(s->d1->sent_messages, seq64be);
     if (item == NULL) {
-        fprintf(stderr, "retransmit:  message %d non-existant\n", seq);
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_RETRANSMIT_MESSAGE,
+                 ERR_R_INTERNAL_ERROR);
         *found = 0;
         return 0;
     }
@@ -1185,7 +1129,8 @@ dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
     s->compress = frag->msg_header.saved_retransmit_state.compress;
     s->session = frag->msg_header.saved_retransmit_state.session;
     DTLS_RECORD_LAYER_set_saved_w_epoch(&s->rlayer,
-        frag->msg_header.saved_retransmit_state.epoch);
+                                        frag->msg_header.
+                                        saved_retransmit_state.epoch);
 
     ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
                          SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
@@ -1199,26 +1144,13 @@ dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
 
     s->d1->retransmitting = 0;
 
-    (void)BIO_flush(SSL_get_wbio(s));
+    (void)BIO_flush(s->wbio);
     return ret;
 }
 
-/* call this function when the buffered messages are no longer needed */
-void dtls1_clear_record_buffer(SSL *s)
-{
-    pitem *item;
-
-    for (item = pqueue_pop(s->d1->sent_messages);
-         item != NULL; item = pqueue_pop(s->d1->sent_messages)) {
-        dtls1_hm_fragment_free((hm_fragment *)item->data);
-        pitem_free(item);
-    }
-}
-
-void dtls1_set_message_header(SSL *s, unsigned char *p,
-                                        unsigned char mt, unsigned long len,
-                                        unsigned long frag_off,
-                                        unsigned long frag_len)
+void dtls1_set_message_header(SSL *s,
+                              unsigned char mt, size_t len,
+                              size_t frag_off, size_t frag_len)
 {
     if (frag_off == 0) {
         s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
@@ -1232,8 +1164,8 @@ void dtls1_set_message_header(SSL *s, unsigned char *p,
 /* don't actually do the writing, wait till the MTU has been retrieved */
 static void
 dtls1_set_message_header_int(SSL *s, unsigned char mt,
-                             unsigned long len, unsigned short seq_num,
-                             unsigned long frag_off, unsigned long frag_len)
+                             size_t len, unsigned short seq_num,
+                             size_t frag_off, size_t frag_len)
 {
     struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
 
@@ -1245,8 +1177,7 @@ dtls1_set_message_header_int(SSL *s, unsigned char mt,
 }
 
 static void
-dtls1_fix_message_header(SSL *s, unsigned long frag_off,
-                         unsigned long frag_len)
+dtls1_fix_message_header(SSL *s, size_t frag_off, size_t frag_len)
 {
     struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
 
@@ -1268,8 +1199,7 @@ static unsigned char *dtls1_write_message_header(SSL *s, unsigned char *p)
     return p;
 }
 
-void
-dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
+void dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
 {
     memset(msg_hdr, 0, sizeof(*msg_hdr));
     msg_hdr->type = *(data++);
@@ -1280,4 +1210,52 @@ dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
     n2l3(data, msg_hdr->frag_len);
 }
 
+int dtls1_set_handshake_header(SSL *s, WPACKET *pkt, int htype)
+{
+    unsigned char *header;
+
+    if (htype == SSL3_MT_CHANGE_CIPHER_SPEC) {
+        s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
+        dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
+                                     s->d1->handshake_write_seq, 0, 0);
+        if (!WPACKET_put_bytes_u8(pkt, SSL3_MT_CCS))
+            return 0;
+    } else {
+        dtls1_set_message_header(s, htype, 0, 0, 0);
+        /*
+         * We allocate space at the start for the message header. This gets
+         * filled in later
+         */
+        if (!WPACKET_allocate_bytes(pkt, DTLS1_HM_HEADER_LENGTH, &header)
+                || !WPACKET_start_sub_packet(pkt))
+            return 0;
+    }
+
+    return 1;
+}
+
+int dtls1_close_construct_packet(SSL *s, WPACKET *pkt, int htype)
+{
+    size_t msglen;
+
+    if ((htype != SSL3_MT_CHANGE_CIPHER_SPEC && !WPACKET_close(pkt))
+            || !WPACKET_get_length(pkt, &msglen)
+            || msglen > INT_MAX)
+        return 0;
+
+    if (htype != SSL3_MT_CHANGE_CIPHER_SPEC) {
+        s->d1->w_msg_hdr.msg_len = msglen - DTLS1_HM_HEADER_LENGTH;
+        s->d1->w_msg_hdr.frag_len = msglen - DTLS1_HM_HEADER_LENGTH;
+    }
+    s->init_num = (int)msglen;
+    s->init_off = 0;
 
+    if (htype != DTLS1_MT_HELLO_VERIFY_REQUEST) {
+        /* Buffer the message to handle re-xmits */
+        if (!dtls1_buffer_message(s, htype == SSL3_MT_CHANGE_CIPHER_SPEC
+                                     ? 1 : 0))
+            return 0;
+    }
+
+    return 1;
+}