Move ossl_assert
[openssl.git] / ssl / statem / statem_dtls.c
index 46843ce0fccef0524c55ec5d2cb652e90ae86512..7fb6cdb8e2ab761d256dc609d796e5a559537c85 100644 (file)
@@ -12,6 +12,7 @@
 #include <stdio.h>
 #include "../ssl_locl.h"
 #include "statem_locl.h"
+#include "internal/cryptlib.h"
 #include <openssl/buffer.h>
 #include <openssl/objects.h>
 #include <openssl/evp.h>
@@ -32,7 +33,6 @@
 
 #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--) \
@@ -43,18 +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;
@@ -111,9 +110,10 @@ 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;
@@ -122,9 +122,11 @@ int dtls1_do_write(SSL *s, int type)
         /* 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
@@ -214,9 +216,8 @@ 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
@@ -236,7 +237,8 @@ int dtls1_do_write(SSL *s, int type)
                                        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
@@ -254,7 +256,7 @@ int dtls1_do_write(SSL *s, int type)
                 } else
                     return -1;
             } else {
-                return (-1);
+                return -1;
             }
         } else {
 
@@ -262,7 +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) {
                 /*
@@ -272,7 +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) {
                     /*
@@ -285,17 +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;
                 }
 
                 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,
@@ -304,12 +307,12 @@ 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;
-            ret -= DTLS1_HM_HEADER_LENGTH;
-            frag_off += ret;
+            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
@@ -320,32 +323,34 @@ int dtls1_do_write(SSL *s, int type)
             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) {
@@ -355,7 +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;
     }
 
@@ -383,11 +387,23 @@ 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;
@@ -397,15 +413,16 @@ 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) {
+    if ((frag_off + frag_len) > msg_len
+            || msg_len > dtls1_max_handshake_message_len(s)) {
         SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT, SSL_R_EXCESSIVE_MESSAGE_SIZE);
         return SSL_AD_ILLEGAL_PARAMETER;
     }
 
     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);
@@ -429,7 +446,7 @@ static int dtls1_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr)
     return 0;                   /* no error */
 }
 
-static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
+static int dtls1_retrieve_buffered_fragment(SSL *s, size_t *len)
 {
     /*-
      * (0) check whether the desired fragment is available
@@ -441,19 +458,29 @@ static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
     hm_fragment *frag;
     int al;
 
-    *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);
@@ -469,47 +496,35 @@ static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
         pitem_free(item);
 
         if (al == 0) {
-            *ok = 1;
-            return frag_len;
+            *len = frag_len;
+            return 1;
         }
 
         ssl3_send_alert(s, SSL3_AL_FATAL, al);
         s->init_num = 0;
-        *ok = 0;
-        return -1;
-    } 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;
+    } else {
+        return 0;
+    }
 }
 
 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));
@@ -546,10 +561,10 @@ 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;
     }
@@ -557,8 +572,8 @@ 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;
@@ -566,6 +581,8 @@ 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);
 
@@ -588,7 +605,8 @@ 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;
@@ -596,19 +614,18 @@ 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;
@@ -641,14 +658,15 @@ 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;
@@ -664,8 +682,9 @@ 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;
@@ -684,7 +703,8 @@ 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;
@@ -692,33 +712,33 @@ 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;
+    size_t mlen, frag_off, frag_len;
     int i, al, 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;
+    if (dtls1_retrieve_buffered_fragment(s, &frag_len)) {
+        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) {
@@ -729,17 +749,17 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
             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) {
+    if (readbytes != DTLS1_HM_HEADER_LENGTH) {
         al = SSL_AD_UNEXPECTED_MESSAGE;
         SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
         goto f_err;
@@ -757,7 +777,7 @@ 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;
+        al = SSL_AD_ILLEGAL_PARAMETER;
         SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
         goto f_err;
     }
@@ -769,17 +789,19 @@ 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
@@ -810,7 +832,7 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
             (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
@@ -818,19 +840,20 @@ 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) {
+        al = SSL_AD_ILLEGAL_PARAMETER;
+        SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
         goto f_err;
     }
 
@@ -846,7 +869,7 @@ static int dtls_get_reassembled_message(SSL *s, long *len)
  f_err:
     ssl3_send_alert(s, SSL3_AL_FATAL, al);
     s->init_num = 0;
-    *len = -1;
+    *len = 0;
     return 0;
 }
 
@@ -859,30 +882,15 @@ 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)) {
+            SSLerr(SSL_F_DTLS_CONSTRUCT_CHANGE_CIPHER_SPEC, ERR_R_INTERNAL_ERROR);
+            ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
+        }
     }
 
     return 1;
@@ -923,13 +931,8 @@ int dtls1_read_failed(SSL *s, int code)
          */
         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;
@@ -985,7 +988,8 @@ 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 == NULL)
@@ -995,13 +999,15 @@ int dtls1_buffer_message(SSL *s, int is_ccs)
 
     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;
@@ -1049,11 +1055,6 @@ int dtls1_retransmit_message(SSL *s, unsigned short seq, int *found)
     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);
@@ -1117,21 +1118,9 @@ int dtls1_retransmit_message(SSL *s, unsigned short seq, int *found)
     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 mt, unsigned long len,
-                              unsigned long frag_off, unsigned long frag_len)
+                              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;
@@ -1145,8 +1134,8 @@ void dtls1_set_message_header(SSL *s,
 /* 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;
 
@@ -1158,7 +1147,7 @@ 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;
 
@@ -1190,3 +1179,53 @@ void dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
     n2l3(data, msg_hdr->frag_off);
     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;
+}