e3d0dae7cf
The existing implementation of DTLSv1_listen() is fundamentally flawed. This function is used in DTLS solutions to listen for new incoming connections from DTLS clients. A client will send an initial ClientHello. The server will respond with a HelloVerifyRequest containing a unique cookie. The client the responds with a second ClientHello - which this time contains the cookie. Once the cookie has been verified then DTLSv1_listen() returns to user code, which is typically expected to continue the handshake with a call to (for example) SSL_accept(). Whilst listening for incoming ClientHellos, the underlying BIO is usually in an unconnected state. Therefore ClientHellos can come in from *any* peer. The arrival of the first ClientHello without the cookie, and the second one with it, could be interspersed with other intervening messages from different clients. The whole purpose of this mechanism is as a defence against DoS attacks. The idea is to avoid allocating state on the server until the client has verified that it is capable of receiving messages at the address it claims to come from. However the existing DTLSv1_listen() implementation completely fails to do this. It attempts to super-impose itself on the standard state machine and reuses all of this code. However the standard state machine expects to operate in a stateful manner with a single client, and this can cause various problems. A second more minor issue is that the return codes from this function are quite confused, with no distinction made between fatal and non-fatal errors. Most user code treats all errors as non-fatal, and simply retries the call to DTLSv1_listen(). This commit completely rewrites the implementation of DTLSv1_listen() and provides a stand alone implementation that does not rely on the existing state machine. It also provides more consistent return codes. Reviewed-by: Andy Polyakov <appro@openssl.org>
356 lines
14 KiB
C
356 lines
14 KiB
C
/* ssl/record/record.h */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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/* ====================================================================
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* Copyright (c) 1998-2015 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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* This product includes cryptographic software written by Eric Young
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* (eay@cryptsoft.com). This product includes software written by Tim
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* Hudson (tjh@cryptsoft.com).
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*
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*/
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#include <openssl/pqueue.h>
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/*****************************************************************************
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* *
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* These structures should be considered PRIVATE to the record layer. No *
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* non-record layer code should be using these structures in any way. *
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* *
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*****************************************************************************/
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typedef struct ssl3_buffer_st {
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/* at least SSL3_RT_MAX_PACKET_SIZE bytes, see ssl3_setup_buffers() */
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unsigned char *buf;
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/* buffer size */
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size_t len;
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/* where to 'copy from' */
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int offset;
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/* how many bytes left */
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int left;
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} SSL3_BUFFER;
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#define SEQ_NUM_SIZE 8
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typedef struct ssl3_record_st {
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/* Record layer version */
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/* r */
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int rec_version;
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/* type of record */
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/* r */
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int type;
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/* How many bytes available */
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/* rw */
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unsigned int length;
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/*
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* How many bytes were available before padding was removed? This is used
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* to implement the MAC check in constant time for CBC records.
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*/
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/* rw */
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unsigned int orig_len;
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/* read/write offset into 'buf' */
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/* r */
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unsigned int off;
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/* pointer to the record data */
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/* rw */
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unsigned char *data;
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/* where the decode bytes are */
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/* rw */
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unsigned char *input;
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/* only used with decompression - malloc()ed */
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/* r */
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unsigned char *comp;
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/* epoch number, needed by DTLS1 */
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/* r */
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unsigned long epoch;
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/* sequence number, needed by DTLS1 */
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/* r */
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unsigned char seq_num[SEQ_NUM_SIZE];
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} SSL3_RECORD;
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typedef struct dtls1_bitmap_st {
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/* Track 32 packets on 32-bit systems and 64 - on 64-bit systems */
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unsigned long map;
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/* Max record number seen so far, 64-bit value in big-endian encoding */
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unsigned char max_seq_num[SEQ_NUM_SIZE];
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} DTLS1_BITMAP;
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typedef struct record_pqueue_st {
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unsigned short epoch;
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pqueue q;
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} record_pqueue;
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typedef struct dtls1_record_data_st {
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unsigned char *packet;
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unsigned int packet_length;
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SSL3_BUFFER rbuf;
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SSL3_RECORD rrec;
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# ifndef OPENSSL_NO_SCTP
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struct bio_dgram_sctp_rcvinfo recordinfo;
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# endif
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} DTLS1_RECORD_DATA;
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typedef struct dtls_record_layer_st {
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/*
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* The current data and handshake epoch. This is initially
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* undefined, and starts at zero once the initial handshake is
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* completed
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*/
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unsigned short r_epoch;
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unsigned short w_epoch;
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/* records being received in the current epoch */
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DTLS1_BITMAP bitmap;
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/* renegotiation starts a new set of sequence numbers */
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DTLS1_BITMAP next_bitmap;
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/* Received handshake records (processed and unprocessed) */
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record_pqueue unprocessed_rcds;
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record_pqueue processed_rcds;
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/*
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* Buffered application records. Only for records between CCS and
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* Finished to prevent either protocol violation or unnecessary message
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* loss.
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*/
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record_pqueue buffered_app_data;
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/*
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* storage for Alert/Handshake protocol data received but not yet
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* processed by ssl3_read_bytes:
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*/
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unsigned char alert_fragment[DTLS1_AL_HEADER_LENGTH];
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unsigned int alert_fragment_len;
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unsigned char handshake_fragment[DTLS1_HM_HEADER_LENGTH];
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unsigned int handshake_fragment_len;
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/* save last and current sequence numbers for retransmissions */
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unsigned char last_write_sequence[8];
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unsigned char curr_write_sequence[8];
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} DTLS_RECORD_LAYER;
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/*****************************************************************************
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* *
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* This structure should be considered "opaque" to anything outside of the *
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* record layer. No non-record layer code should be accessing the members of *
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* this structure. *
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* *
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*****************************************************************************/
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typedef struct record_layer_st {
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/* The parent SSL structure */
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SSL *s;
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/*
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* Read as many input bytes as possible (for
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* non-blocking reads)
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*/
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int read_ahead;
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/* where we are when reading */
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int rstate;
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/* read IO goes into here */
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SSL3_BUFFER rbuf;
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/* write IO goes into here */
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SSL3_BUFFER wbuf;
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/* each decoded record goes in here */
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SSL3_RECORD rrec;
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/* goes out from here */
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SSL3_RECORD wrec;
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/* used internally to point at a raw packet */
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unsigned char *packet;
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unsigned int packet_length;
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/* number of bytes sent so far */
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unsigned int wnum;
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/*
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* storage for Alert/Handshake protocol data received but not yet
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* processed by ssl3_read_bytes:
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*/
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unsigned char alert_fragment[2];
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unsigned int alert_fragment_len;
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unsigned char handshake_fragment[4];
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unsigned int handshake_fragment_len;
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/* partial write - check the numbers match */
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/* number bytes written */
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int wpend_tot;
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int wpend_type;
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/* number of bytes submitted */
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int wpend_ret;
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const unsigned char *wpend_buf;
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unsigned char read_sequence[SEQ_NUM_SIZE];
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unsigned char write_sequence[SEQ_NUM_SIZE];
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DTLS_RECORD_LAYER *d;
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} RECORD_LAYER;
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/*****************************************************************************
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* *
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* The following macros/functions represent the libssl internal API to the *
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* record layer. Any libssl code may call these functions/macros *
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* *
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*****************************************************************************/
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#define MIN_SSL2_RECORD_LEN 9
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#define RECORD_LAYER_set_read_ahead(rl, ra) ((rl)->read_ahead = (ra))
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#define RECORD_LAYER_get_read_ahead(rl) ((rl)->read_ahead)
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#define RECORD_LAYER_get_packet(rl) ((rl)->packet)
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#define RECORD_LAYER_get_packet_length(rl) ((rl)->packet_length)
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#define RECORD_LAYER_add_packet_length(rl, inc) ((rl)->packet_length += (inc))
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#define DTLS_RECORD_LAYER_get_w_epoch(rl) ((rl)->d->w_epoch)
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#define DTLS_RECORD_LAYER_get_processed_rcds(rl) \
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((rl)->d->processed_rcds)
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#define DTLS_RECORD_LAYER_get_unprocessed_rcds(rl) \
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((rl)->d->unprocessed_rcds)
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void RECORD_LAYER_init(RECORD_LAYER *rl, SSL *s);
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void RECORD_LAYER_clear(RECORD_LAYER *rl);
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void RECORD_LAYER_release(RECORD_LAYER *rl);
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int RECORD_LAYER_read_pending(RECORD_LAYER *rl);
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int RECORD_LAYER_write_pending(RECORD_LAYER *rl);
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int RECORD_LAYER_set_data(RECORD_LAYER *rl, const unsigned char *buf, int len);
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void RECORD_LAYER_dup(RECORD_LAYER *dst, RECORD_LAYER *src);
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void RECORD_LAYER_reset_read_sequence(RECORD_LAYER *rl);
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void RECORD_LAYER_reset_write_sequence(RECORD_LAYER *rl);
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int RECORD_LAYER_setup_comp_buffer(RECORD_LAYER *rl);
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int RECORD_LAYER_is_sslv2_record(RECORD_LAYER *rl);
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unsigned int RECORD_LAYER_get_rrec_length(RECORD_LAYER *rl);
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__owur int ssl3_pending(const SSL *s);
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__owur int ssl3_write_bytes(SSL *s, int type, const void *buf, int len);
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__owur int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
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unsigned int len, int create_empty_fragment);
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__owur int ssl3_read_bytes(SSL *s, int type, int *recvd_type,
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unsigned char *buf, int len, int peek);
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__owur int ssl3_setup_buffers(SSL *s);
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__owur int ssl3_enc(SSL *s, int send_data);
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__owur int n_ssl3_mac(SSL *ssl, unsigned char *md, int send_data);
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__owur int ssl3_write_pending(SSL *s, int type, const unsigned char *buf,
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unsigned int len);
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__owur int tls1_enc(SSL *s, int snd);
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__owur int tls1_mac(SSL *ssl, unsigned char *md, int snd);
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int DTLS_RECORD_LAYER_new(RECORD_LAYER *rl);
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void DTLS_RECORD_LAYER_free(RECORD_LAYER *rl);
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void DTLS_RECORD_LAYER_clear(RECORD_LAYER *rl);
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void DTLS_RECORD_LAYER_set_saved_w_epoch(RECORD_LAYER *rl, unsigned short e);
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void DTLS_RECORD_LAYER_clear(RECORD_LAYER *rl);
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void DTLS_RECORD_LAYER_resync_write(RECORD_LAYER *rl);
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void DTLS_RECORD_LAYER_set_write_sequence(RECORD_LAYER *rl, unsigned char *seq);
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__owur int dtls1_read_bytes(SSL *s, int type, int *recvd_type,
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unsigned char *buf, int len, int peek);
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__owur int dtls1_write_bytes(SSL *s, int type, const void *buf, int len);
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__owur int do_dtls1_write(SSL *s, int type, const unsigned char *buf,
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unsigned int len, int create_empty_fragement);
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void dtls1_reset_seq_numbers(SSL *s, int rw);
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