initial/final commitHEADmaster

1 files changed, 1220 insertions, 0 deletions

diff --git a/openssl-1.1.0h/ssl/statem/statem_dtls.c b/openssl-1.1.0h/ssl/statem/statem_dtls.c
new file mode 100644
index 0000000..6b80620
--- /dev/null
+++ b/openssl-1.1.0h/ssl/statem/statem_dtls.c
@@ -0,0 +1,1220 @@
+/*
+ * Copyright 2005-2018 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * 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 <openssl/buffer.h>
+#include <openssl/objects.h>
+#include <openssl/evp.h>
+#include <openssl/x509.h>
+
+#define RSMBLY_BITMASK_SIZE(msg_len) (((msg_len) + 7) / 8)
+
+#define RSMBLY_BITMASK_MARK(bitmask, start, end) { \
+                        if ((end) - (start) <= 8) { \
+                                long ii; \
+                                for (ii = (start); ii < (end); ii++) bitmask[((ii) >> 3)] |= (1 << ((ii) & 7)); \
+                        } else { \
+                                long ii; \
+                                bitmask[((start) >> 3)] |= bitmask_start_values[((start) & 7)]; \
+                                for (ii = (((start) >> 3) + 1); ii < ((((end) - 1)) >> 3); ii++) bitmask[ii] = 0xff; \
+                                bitmask[(((end) - 1) >> 3)] |= bitmask_end_values[((end) & 7)]; \
+                        } }
+
+#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--) \
+                                if (bitmask[ii] != 0xff) { is_complete = 0; break; } }
+
+static unsigned char bitmask_start_values[] =
+    { 0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80 };
+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 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,
+                                         unsigned short seq_num,
+                                         unsigned long frag_off,
+                                         unsigned long frag_len);
+static int dtls_get_reassembled_message(SSL *s, long *len);
+
+static hm_fragment *dtls1_hm_fragment_new(unsigned long frag_len,
+                                          int reassembly)
+{
+    hm_fragment *frag = NULL;
+    unsigned char *buf = NULL;
+    unsigned char *bitmask = NULL;
+
+    frag = OPENSSL_malloc(sizeof(*frag));
+    if (frag == NULL)
+        return NULL;
+
+    if (frag_len) {
+        buf = OPENSSL_malloc(frag_len);
+        if (buf == NULL) {
+            OPENSSL_free(frag);
+            return NULL;
+        }
+    }
+
+    /* zero length fragment gets zero frag->fragment */
+    frag->fragment = buf;
+
+    /* Initialize reassembly bitmask if necessary */
+    if (reassembly) {
+        bitmask = OPENSSL_zalloc(RSMBLY_BITMASK_SIZE(frag_len));
+        if (bitmask == NULL) {
+            OPENSSL_free(buf);
+            OPENSSL_free(frag);
+            return NULL;
+        }
+    }
+
+    frag->reassembly = bitmask;
+
+    return frag;
+}
+
+void dtls1_hm_fragment_free(hm_fragment *frag)
+{
+    if (!frag)
+        return;
+    if (frag->msg_header.is_ccs) {
+        EVP_CIPHER_CTX_free(frag->msg_header.
+                            saved_retransmit_state.enc_write_ctx);
+        EVP_MD_CTX_free(frag->msg_header.saved_retransmit_state.write_hash);
+    }
+    OPENSSL_free(frag->fragment);
+    OPENSSL_free(frag->reassembly);
+    OPENSSL_free(frag);
+}
+
+/*
+ * send s->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or
+ * SSL3_RT_CHANGE_CIPHER_SPEC)
+ */
+int dtls1_do_write(SSL *s, int type)
+{
+    int ret;
+    unsigned int curr_mtu;
+    int retry = 1;
+    unsigned int len, frag_off, mac_size, blocksize, used_len;
+
+    if (!dtls1_query_mtu(s))
+        return -1;
+
+    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->write_hash) {
+        if (s->enc_write_ctx
+            && (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);
+    } else
+        mac_size = 0;
+
+    if (s->enc_write_ctx &&
+        (EVP_CIPHER_CTX_mode(s->enc_write_ctx) == EVP_CIPH_CBC_MODE))
+        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) {
+        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;
+        else
+            curr_mtu = 0;
+
+        if (curr_mtu <= DTLS1_HM_HEADER_LENGTH) {
+            /*
+             * grr.. we could get an error if MTU picked was wrong
+             */
+            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;
+            } else {
+                /* Shouldn't happen */
+                return -1;
+            }
+        }
+
+        /*
+         * 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;
+
+        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 (len < DTLS1_HM_HEADER_LENGTH) {
+                /*
+                 * len is so small that we really can't do anything sensible
+                 * so fail
+                 */
+                return -1;
+            }
+            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);
+        if (ret < 0) {
+            /*
+             * might need to update MTU here, but we don't know which
+             * previous packet caused the failure -- so can't really
+             * retransmit anything.  continue as if everything is fine and
+             * wait for an alert to handle the retransmit
+             */
+            if (retry && BIO_ctrl(SSL_get_wbio(s),
+                                  BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0) {
+                if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
+                    if (!dtls1_query_mtu(s))
+                        return -1;
+                    /* Have one more go */
+                    retry = 0;
+                } else
+                    return -1;
+            } else {
+                return (-1);
+            }
+        } else {
+
+            /*
+             * 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 (type == SSL3_RT_HANDSHAKE && !s->d1->retransmitting) {
+                /*
+                 * should not be done for 'Hello Request's, but in that case
+                 * we'll ignore the result anyway
+                 */
+                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;
+
+                if (frag_off == 0 && s->version != DTLS1_BAD_VER) {
+                    /*
+                     * reconstruct message header is if it is being sent in
+                     * 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);
+                    p -= DTLS1_HM_HEADER_LENGTH;
+                    xlen = ret;
+                } else {
+                    p += DTLS1_HM_HEADER_LENGTH;
+                    xlen = ret - DTLS1_HM_HEADER_LENGTH;
+                }
+
+                if (!ssl3_finish_mac(s, p, xlen))
+                    return -1;
+            }
+
+            if (ret == 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,
+                                    s->msg_callback_arg);
+
+                s->init_off = 0; /* done writing this message */
+                s->init_num = 0;
+
+                return (1);
+            }
+            s->init_off += ret;
+            s->init_num -= ret;
+            ret -= DTLS1_HM_HEADER_LENGTH;
+            frag_off += ret;
+
+            /*
+             * 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);
+}
+
+int dtls_get_message(SSL *s, int *mt, unsigned long *len)
+{
+    struct hm_header_st *msg_hdr;
+    unsigned char *p;
+    unsigned long msg_len;
+    int ok;
+    long tmplen;
+
+    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) {
+        return 0;
+    }
+
+    *mt = s->s3->tmp.message_type;
+
+    p = (unsigned char *)s->init_buf->data;
+
+    if (*mt == SSL3_MT_CHANGE_CIPHER_SPEC) {
+        if (s->msg_callback) {
+            s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC,
+                            p, 1, s, s->msg_callback_arg);
+        }
+        /*
+         * This isn't a real handshake message so skip the processing below.
+         */
+        *len = (unsigned long)tmplen;
+        return 1;
+    }
+
+    msg_len = msg_hdr->msg_len;
+
+    /* reconstruct message header */
+    *(p++) = msg_hdr->type;
+    l2n3(msg_len, p);
+    s2n(msg_hdr->seq, p);
+    l2n3(0, p);
+    l2n3(msg_len, p);
+    if (s->version != DTLS1_BAD_VER) {
+        p -= DTLS1_HM_HEADER_LENGTH;
+        msg_len += DTLS1_HM_HEADER_LENGTH;
+    }
+
+    /*
+     * 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);
+
+    memset(msg_hdr, 0, sizeof(*msg_hdr));
+
+    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 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_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr)
+{
+    size_t frag_off, frag_len, msg_len;
+
+    msg_len = msg_hdr->msg_len;
+    frag_off = msg_hdr->frag_off;
+    frag_len = msg_hdr->frag_len;
+
+    /* sanity checking */
+    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
+         * 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;
+        }
+
+        s->s3->tmp.message_size = msg_len;
+        s->d1->r_msg_hdr.msg_len = msg_len;
+        s->s3->tmp.message_type = msg_hdr->type;
+        s->d1->r_msg_hdr.type = msg_hdr->type;
+        s->d1->r_msg_hdr.seq = msg_hdr->seq;
+    } else if (msg_len != s->d1->r_msg_hdr.msg_len) {
+        /*
+         * 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;
+    }
+
+    return 0;                   /* no error */
+}
+
+static int dtls1_retrieve_buffered_fragment(SSL *s, int *ok)
+{
+    /*-
+     * (0) check whether the desired fragment is available
+     * if so:
+     * (1) copy over the fragment to s->init_buf->data[]
+     * (2) update s->init_num
+     */
+    pitem *item;
+    hm_fragment *frag;
+    int al;
+
+    *ok = 0;
+
+    do {
+        item = pqueue_peek(s->d1->buffered_messages);
+        if (item == NULL)
+            return 0;
+
+        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;
+        pqueue_pop(s->d1->buffered_messages);
+
+        al = dtls1_preprocess_fragment(s, &frag->msg_header);
+
+        if (al == 0) {          /* no alert */
+            unsigned char *p =
+                (unsigned char *)s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
+            memcpy(&p[frag->msg_header.frag_off], frag->fragment,
+                   frag->msg_header.frag_len);
+        }
+
+        dtls1_hm_fragment_free(frag);
+        pitem_free(item);
+
+        if (al == 0) {
+            *ok = 1;
+            return frag_len;
+        }
+
+        ssl3_send_alert(s, SSL3_AL_FATAL, al);
+        s->init_num = 0;
+        *ok = 0;
+        return -1;
+    } else
+        return 0;
+}
+
+static int
+dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr, int *ok)
+{
+    hm_fragment *frag = NULL;
+    pitem *item = NULL;
+    int i = -1, is_complete;
+    unsigned char seq64be[8];
+    unsigned long frag_len = msg_hdr->frag_len;
+
+    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)
+        return DTLS1_HM_FRAGMENT_RETRY;
+
+    /* Try to find item in queue */
+    memset(seq64be, 0, sizeof(seq64be));
+    seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
+    seq64be[7] = (unsigned char)msg_hdr->seq;
+    item = pqueue_find(s->d1->buffered_messages, seq64be);
+
+    if (item == NULL) {
+        frag = dtls1_hm_fragment_new(msg_hdr->msg_len, 1);
+        if (frag == NULL)
+            goto err;
+        memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
+        frag->msg_header.frag_len = frag->msg_header.msg_len;
+        frag->msg_header.frag_off = 0;
+    } else {
+        frag = (hm_fragment *)item->data;
+        if (frag->msg_header.msg_len != msg_hdr->msg_len) {
+            item = NULL;
+            frag = NULL;
+            goto err;
+        }
+    }
+
+    /*
+     * If message is already reassembled, this must be a retransmit and can
+     * be dropped. In this case item != NULL and so frag does not need to be
+     * freed.
+     */
+    if (frag->reassembly == NULL) {
+        unsigned char devnull[256];
+
+        while (frag_len) {
+            i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
+                                          devnull,
+                                          frag_len >
+                                          sizeof(devnull) ? sizeof(devnull) :
+                                          frag_len, 0);
+            if (i <= 0)
+                goto err;
+            frag_len -= i;
+        }
+        return DTLS1_HM_FRAGMENT_RETRY;
+    }
+
+    /* 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)
+        i = -1;
+    if (i <= 0)
+        goto err;
+
+    RSMBLY_BITMASK_MARK(frag->reassembly, (long)msg_hdr->frag_off,
+                        (long)(msg_hdr->frag_off + frag_len));
+
+    RSMBLY_BITMASK_IS_COMPLETE(frag->reassembly, (long)msg_hdr->msg_len,
+                               is_complete);
+
+    if (is_complete) {
+        OPENSSL_free(frag->reassembly);
+        frag->reassembly = NULL;
+    }
+
+    if (item == NULL) {
+        item = pitem_new(seq64be, frag);
+        if (item == NULL) {
+            i = -1;
+            goto err;
+        }
+
+        item = pqueue_insert(s->d1->buffered_messages, item);
+        /*
+         * pqueue_insert fails iff a duplicate item is inserted. However,
+         * |item| cannot be a duplicate. If it were, |pqueue_find|, above,
+         * would have returned it and control would never have reached this
+         * branch.
+         */
+        OPENSSL_assert(item != NULL);
+    }
+
+    return DTLS1_HM_FRAGMENT_RETRY;
+
+ err:
+    if (item == NULL)
+        dtls1_hm_fragment_free(frag);
+    *ok = 0;
+    return i;
+}
+
+static int
+dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr,
+                                 int *ok)
+{
+    int i = -1;
+    hm_fragment *frag = NULL;
+    pitem *item = NULL;
+    unsigned char seq64be[8];
+    unsigned long frag_len = msg_hdr->frag_len;
+
+    if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len)
+        goto err;
+
+    /* Try to find item in queue, to prevent duplicate entries */
+    memset(seq64be, 0, sizeof(seq64be));
+    seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
+    seq64be[7] = (unsigned char)msg_hdr->seq;
+    item = pqueue_find(s->d1->buffered_messages, seq64be);
+
+    /*
+     * If we already have an entry and this one is a fragment, don't discard
+     * it and rather try to reassemble it.
+     */
+    if (item != NULL && frag_len != msg_hdr->msg_len)
+        item = NULL;
+
+    /*
+     * Discard the message if sequence number was already there, is too far
+     * in the future, already in the queue or if we received a FINISHED
+     * before the SERVER_HELLO, which then must be a stale retransmit.
+     */
+    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)) {
+        unsigned char devnull[256];
+
+        while (frag_len) {
+            i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
+                                          devnull,
+                                          frag_len >
+                                          sizeof(devnull) ? sizeof(devnull) :
+                                          frag_len, 0);
+            if (i <= 0)
+                goto err;
+            frag_len -= i;
+        }
+    } else {
+        if (frag_len != msg_hdr->msg_len)
+            return dtls1_reassemble_fragment(s, msg_hdr, ok);
+
+        if (frag_len > dtls1_max_handshake_message_len(s))
+            goto err;
+
+        frag = dtls1_hm_fragment_new(frag_len, 0);
+        if (frag == NULL)
+            goto err;
+
+        memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
+
+        if (frag_len) {
+            /*
+             * 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)
+                i = -1;
+            if (i <= 0)
+                goto err;
+        }
+
+        item = pitem_new(seq64be, frag);
+        if (item == NULL)
+            goto err;
+
+        item = pqueue_insert(s->d1->buffered_messages, item);
+        /*
+         * pqueue_insert fails iff a duplicate item is inserted. However,
+         * |item| cannot be a duplicate. If it were, |pqueue_find|, above,
+         * would have returned it. Then, either |frag_len| !=
+         * |msg_hdr->msg_len| in which case |item| is set to NULL and it will
+         * have been processed with |dtls1_reassemble_fragment|, above, or
+         * the record will have been discarded.
+         */
+        OPENSSL_assert(item != NULL);
+    }
+
+    return DTLS1_HM_FRAGMENT_RETRY;
+
+ err:
+    if (item == NULL)
+        dtls1_hm_fragment_free(frag);
+    *ok = 0;
+    return i;
+}
+
+static int dtls_get_reassembled_message(SSL *s, long *len)
+{
+    unsigned char wire[DTLS1_HM_HEADER_LENGTH];
+    unsigned long mlen, frag_off, frag_len;
+    int i, al, recvd_type;
+    struct hm_header_st msg_hdr;
+    int ok;
+
+ 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;
+        *len = frag_len;
+        return ok;
+    }
+
+    /* read handshake message header */
+    i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, &recvd_type, wire,
+                                  DTLS1_HM_HEADER_LENGTH, 0);
+    if (i <= 0) {               /* nbio, or an error */
+        s->rwstate = SSL_READING;
+        *len = i;
+        return 0;
+    }
+    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);
+            goto f_err;
+        }
+
+        memcpy(s->init_buf->data, wire, i);
+        s->init_num = i - 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;
+        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);
+        goto f_err;
+    }
+
+    /* parse the message fragment header */
+    dtls1_get_message_header(wire, &msg_hdr);
+
+    mlen = msg_hdr.msg_len;
+    frag_off = msg_hdr.frag_off;
+    frag_len = msg_hdr.frag_len;
+
+    /*
+     * We must have at least frag_len bytes left in the record to be read.
+     * 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);
+        goto f_err;
+    }
+
+    /*
+     * if this is a future (or stale) message it gets buffered
+     * (or dropped)--no further processing at this time
+     * While listening, we accept seq 1 (ClientHello with cookie)
+     * 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;
+    }
+
+    if (frag_len && frag_len < mlen) {
+        *len = dtls1_reassemble_fragment(s, &msg_hdr, &ok);
+        return ok;
+    }
+
+    if (!s->server && s->d1->r_msg_hdr.frag_off == 0 &&
+        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
+         * correct. Does not count for 'Finished' MAC.
+         */
+        if (wire[1] == 0 && wire[2] == 0 && wire[3] == 0) {
+            if (s->msg_callback)
+                s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
+                                wire, DTLS1_HM_HEADER_LENGTH, s,
+                                s->msg_callback_arg);
+
+            s->init_num = 0;
+            goto redo;
+        } else {                /* Incorrectly formatted Hello request */
+
+            al = SSL_AD_UNEXPECTED_MESSAGE;
+            SSLerr(SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
+                   SSL_R_UNEXPECTED_MESSAGE);
+            goto f_err;
+        }
+    }
+
+    if ((al = dtls1_preprocess_fragment(s, &msg_hdr)))
+        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);
+
+        /*
+         * This shouldn't ever fail due to NBIO because we already checked
+         * that we have enough data in the record
+         */
+        if (i <= 0) {
+            s->rwstate = SSL_READING;
+            *len = i;
+            return 0;
+        }
+    } else
+        i = 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);
+        goto f_err;
+    }
+
+    /*
+     * Note that s->init_num is *not* used as current offset in
+     * s->init_buf->data, but as a counter summing up fragments' lengths: as
+     * soon as they sum up to handshake packet length, we assume we have got
+     * all the fragments.
+     */
+    *len = s->init_num = frag_len;
+    return 1;
+
+ f_err:
+    ssl3_send_alert(s, SSL3_AL_FATAL, al);
+    s->init_num = 0;
+    *len = -1;
+    return 0;
+}
+
+/*-
+ * for these 2 messages, we need to
+ * ssl->enc_read_ctx                    re-init
+ * ssl->rlayer.read_sequence            zero
+ * ssl->s3->read_mac_secret             re-init
+ * ssl->session->read_sym_enc           assign
+ * ssl->session->read_compression       assign
+ * ssl->session->read_hash              assign
+ */
+int dtls_construct_change_cipher_spec(SSL *s)
+{
+    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;
+    }
+
+    return 1;
+}
+
+#ifndef OPENSSL_NO_SCTP
+/*
+ * Wait for a dry event. Should only be called at a point in the handshake
+ * where we are not expecting any data from the peer (except possibly an alert).
+ */
+WORK_STATE dtls_wait_for_dry(SSL *s)
+{
+    int ret;
+    long len;
+
+    /* read app data until dry event */
+    ret = BIO_dgram_sctp_wait_for_dry(SSL_get_wbio(s));
+    if (ret < 0)
+        return WORK_ERROR;
+
+    if (ret == 0) {
+        /*
+         * We're not expecting any more messages from the peer at this point -
+         * but we could get an alert. If an alert is waiting then we will never
+         * return successfully. Therefore we attempt to read a message. This
+         * should never succeed but will process any waiting alerts.
+         */
+        if (dtls_get_reassembled_message(s, &len)) {
+            /* The call succeeded! This should never happen */
+            SSLerr(SSL_F_DTLS_WAIT_FOR_DRY, SSL_R_UNEXPECTED_MESSAGE);
+            ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
+            ossl_statem_set_error(s);
+            return WORK_ERROR;
+        }
+
+        s->s3->in_read_app_data = 2;
+        s->rwstate = SSL_READING;
+        BIO_clear_retry_flags(SSL_get_rbio(s));
+        BIO_set_retry_read(SSL_get_rbio(s));
+        return WORK_MORE_A;
+    }
+    return WORK_FINISHED_CONTINUE;
+}
+#endif
+
+int dtls1_read_failed(SSL *s, int code)
+{
+    if (code > 0) {
+        SSLerr(SSL_F_DTLS1_READ_FAILED, ERR_R_INTERNAL_ERROR);
+        return 1;
+    }
+
+    if (!dtls1_is_timer_expired(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;
+    }
+
+    return dtls1_handle_timeout(s);
+}
+
+int dtls1_get_queue_priority(unsigned short seq, int is_ccs)
+{
+    /*
+     * The index of the retransmission queue actually is the message sequence
+     * number, since the queue only contains messages of a single handshake.
+     * However, the ChangeCipherSpec has no message sequence number and so
+     * using only the sequence will result in the CCS and Finished having the
+     * same index. To prevent this, the sequence number is multiplied by 2.
+     * In case of a CCS 1 is subtracted. This does not only differ CSS and
+     * Finished, it also maintains the order of the index (important for
+     * priority queues) and fits in the unsigned short variable.
+     */
+    return seq * 2 - is_ccs;
+}
+
+int dtls1_retransmit_buffered_messages(SSL *s)
+{
+    pqueue *sent = s->d1->sent_messages;
+    piterator iter;
+    pitem *item;
+    hm_fragment *frag;
+    int found = 0;
+
+    iter = pqueue_iterator(sent);
+
+    for (item = pqueue_next(&iter); item != NULL; item = pqueue_next(&iter)) {
+        frag = (hm_fragment *)item->data;
+        if (dtls1_retransmit_message(s, (unsigned short)
+                                     dtls1_get_queue_priority
+                                     (frag->msg_header.seq,
+                                      frag->msg_header.is_ccs), &found) <= 0)
+            return -1;
+    }
+
+    return 1;
+}
+
+int dtls1_buffer_message(SSL *s, int is_ccs)
+{
+    pitem *item;
+    hm_fragment *frag;
+    unsigned char seq64be[8];
+
+    /*
+     * this function is called immediately after a message has been
+     * serialized
+     */
+    OPENSSL_assert(s->init_off == 0);
+
+    frag = dtls1_hm_fragment_new(s->init_num, 0);
+    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);
+    } else {
+        OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
+                       DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num);
+    }
+
+    frag->msg_header.msg_len = s->d1->w_msg_hdr.msg_len;
+    frag->msg_header.seq = s->d1->w_msg_hdr.seq;
+    frag->msg_header.type = s->d1->w_msg_hdr.type;
+    frag->msg_header.frag_off = 0;
+    frag->msg_header.frag_len = s->d1->w_msg_hdr.msg_len;
+    frag->msg_header.is_ccs = is_ccs;
+
+    /* save current state */
+    frag->msg_header.saved_retransmit_state.enc_write_ctx = s->enc_write_ctx;
+    frag->msg_header.saved_retransmit_state.write_hash = s->write_hash;
+    frag->msg_header.saved_retransmit_state.compress = s->compress;
+    frag->msg_header.saved_retransmit_state.session = s->session;
+    frag->msg_header.saved_retransmit_state.epoch =
+        DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer);
+
+    memset(seq64be, 0, sizeof(seq64be));
+    seq64be[6] =
+        (unsigned
+         char)(dtls1_get_queue_priority(frag->msg_header.seq,
+                                        frag->msg_header.is_ccs) >> 8);
+    seq64be[7] =
+        (unsigned
+         char)(dtls1_get_queue_priority(frag->msg_header.seq,
+                                        frag->msg_header.is_ccs));
+
+    item = pitem_new(seq64be, frag);
+    if (item == NULL) {
+        dtls1_hm_fragment_free(frag);
+        return 0;
+    }
+
+    pqueue_insert(s->d1->sent_messages, item);
+    return 1;
+}
+
+int dtls1_retransmit_message(SSL *s, unsigned short seq, int *found)
+{
+    int ret;
+    /* XDTLS: for now assuming that read/writes are blocking */
+    pitem *item;
+    hm_fragment *frag;
+    unsigned long header_length;
+    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);
+    seq64be[7] = (unsigned char)seq;
+
+    item = pqueue_find(s->d1->sent_messages, seq64be);
+    if (item == NULL) {
+        SSLerr(SSL_F_DTLS1_RETRANSMIT_MESSAGE, ERR_R_INTERNAL_ERROR);
+        *found = 0;
+        return 0;
+    }
+
+    *found = 1;
+    frag = (hm_fragment *)item->data;
+
+    if (frag->msg_header.is_ccs)
+        header_length = DTLS1_CCS_HEADER_LENGTH;
+    else
+        header_length = DTLS1_HM_HEADER_LENGTH;
+
+    memcpy(s->init_buf->data, frag->fragment,
+           frag->msg_header.msg_len + header_length);
+    s->init_num = frag->msg_header.msg_len + header_length;
+
+    dtls1_set_message_header_int(s, frag->msg_header.type,
+                                 frag->msg_header.msg_len,
+                                 frag->msg_header.seq, 0,
+                                 frag->msg_header.frag_len);
+
+    /* save current state */
+    saved_state.enc_write_ctx = s->enc_write_ctx;
+    saved_state.write_hash = s->write_hash;
+    saved_state.compress = s->compress;
+    saved_state.session = s->session;
+    saved_state.epoch = DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer);
+
+    s->d1->retransmitting = 1;
+
+    /* restore state in which the message was originally sent */
+    s->enc_write_ctx = frag->msg_header.saved_retransmit_state.enc_write_ctx;
+    s->write_hash = frag->msg_header.saved_retransmit_state.write_hash;
+    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);
+
+    ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
+                         SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
+
+    /* restore current state */
+    s->enc_write_ctx = saved_state.enc_write_ctx;
+    s->write_hash = saved_state.write_hash;
+    s->compress = saved_state.compress;
+    s->session = saved_state.session;
+    DTLS_RECORD_LAYER_set_saved_w_epoch(&s->rlayer, saved_state.epoch);
+
+    s->d1->retransmitting = 0;
+
+    (void)BIO_flush(s->wbio);
+    return ret;
+}
+
+void dtls1_set_message_header(SSL *s,
+                              unsigned char mt, unsigned long len,
+                              unsigned long frag_off, unsigned long frag_len)
+{
+    if (frag_off == 0) {
+        s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
+        s->d1->next_handshake_write_seq++;
+    }
+
+    dtls1_set_message_header_int(s, mt, len, s->d1->handshake_write_seq,
+                                 frag_off, frag_len);
+}
+
+/* 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)
+{
+    struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
+
+    msg_hdr->type = mt;
+    msg_hdr->msg_len = len;
+    msg_hdr->seq = seq_num;
+    msg_hdr->frag_off = frag_off;
+    msg_hdr->frag_len = frag_len;
+}
+
+static void
+dtls1_fix_message_header(SSL *s, unsigned long frag_off, unsigned long frag_len)
+{
+    struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
+
+    msg_hdr->frag_off = frag_off;
+    msg_hdr->frag_len = frag_len;
+}
+
+static unsigned char *dtls1_write_message_header(SSL *s, unsigned char *p)
+{
+    struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
+
+    *p++ = msg_hdr->type;
+    l2n3(msg_hdr->msg_len, p);
+
+    s2n(msg_hdr->seq, p);
+    l2n3(msg_hdr->frag_off, p);
+    l2n3(msg_hdr->frag_len, p);
+
+    return p;
+}
+
+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++);
+    n2l3(data, msg_hdr->msg_len);
+
+    n2s(data, msg_hdr->seq);
+    n2l3(data, msg_hdr->frag_off);
+    n2l3(data, msg_hdr->frag_len);
+}