bio.h

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#pragma once
/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
#ifdef WITH_TLS
/**
 * $Id: 413339e8b612f8cf28e93f8bf68c78aebdb98687 $
 *
 * @file lib/tls/bio.h
 * @brief Custom BIOs to pass to OpenSSL's functions
 *
 * @copyright 2021 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSIDH(bio_h, "$Id: 413339e8b612f8cf28e93f8bf68c78aebdb98687 $")
 
#include "openssl_user_macros.h"
 
#include <openssl/bio.h>
#include <freeradius-devel/util/dbuff.h>
 
/** An OpenSSL BIO whose backing store is a (possibly) talloc-extendable buffer
 *
 * The BIO has two dbuffs, a producer and a consumer.  They have
 * the same start pointers, but different end pointers.  The producer
 * writes more data to the memory buffer via fr_tls_bio_dbuff_in(),
 * which updates its end pointer.  The end pointer is shared with the
 * consumer, which sees that data is available, and reads it via
 * fr_tls_bio_dbuff_out().
 *
 * This design allows the producer and consumer to share an underlying
 * memory block, which reduces copies.
 *
 * The dbuff can shift its memory contents around.  A read shifts the
 * data down to reclaim the space which was consumed, and a write
 * shifts the data down in the same way.  A write may also extend the
 * buffer, and talloc extends a buffer by moving the buffer to a new
 * address.  Callers must therefore not cache any pointers, and
 * instead always call the dbuff wrapper functions to get the current
 * values.
 */
typedef struct fr_tls_bio_dbuff_s fr_tls_bio_dbuff_t;
 
/** Window of datagrams which can be in a TLS BIO, but not yet written.
 *
 * The cap serves the same purpose as FR_TLS_MAX_ROUNDS in session.h:
 * it stops the server from holding unbounded state.  A handshake
 * flight is a handful of datagrams even at the smallest possible MTU.
 * Any write which would exceed this limit fails, rather than growing
 * the queue.
 */
#define FR_TLS_MAX_DATAGRAMS (256)
 
uint8_t         *fr_tls_bio_dbuff_finalise(fr_tls_bio_dbuff_t *bd);
 
char            *fr_tls_bio_dbuff_finalise_bstr(fr_tls_bio_dbuff_t *bd);
 
fr_dbuff_t      *fr_tls_bio_dbuff_out(fr_tls_bio_dbuff_t *bd);
 
fr_dbuff_t      *fr_tls_bio_dbuff_in(fr_tls_bio_dbuff_t *bd);
 
void            fr_tls_bio_dbuff_reset(fr_tls_bio_dbuff_t *bd);
 
void            fr_tls_bio_dbuff_clear(fr_tls_bio_dbuff_t *bd);
 
BIO             *fr_tls_bio_dbuff_alloc(fr_tls_bio_dbuff_t **out, TALLOC_CTX *bio_ctx, TALLOC_CTX *buff_ctx,
                                         size_t init, size_t max, bool free_buff);
 
uint8_t         *fr_tls_bio_dbuff_thread_local_finalise(void);
 
char            *fr_tls_bio_dbuff_thread_local_finalise_bstr(void);
 
void            fr_tls_bio_dbuff_thread_local_clear(void);
 
BIO             *fr_tls_bio_dbuff_thread_local(TALLOC_CTX *ctx, size_t init, size_t max);
 
int             fr_tls_bio_dbuff_datagram_init(fr_tls_bio_dbuff_t *bd);
 
size_t          fr_tls_bio_dbuff_datagram_len(fr_tls_bio_dbuff_t *bd);
 
void            fr_tls_bio_dbuff_datagram_sent(fr_tls_bio_dbuff_t *bd);
 
int             fr_tls_bio_init(void);
 
void            fr_tls_bio_free(void);
 
#endif /* WITH_TLS */