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boringssl/ssl/d1_both.c
David Benjamin 61672818ef Check for buffered handshake messages on cipher change in DTLS. 
This is the equivalent of FragmentAcrossChangeCipherSuite for DTLS. It
is possible for us to, while receiving pre-CCS handshake messages, to
buffer up a message with sequence number meant for a post-CCS Finished.
When we then get to the new epoch and attempt to read the Finished, we
will process the buffered Finished although it was sent with the wrong
encryption.

Move ssl_set_{read,write}_state to SSL_PROTOCOL_METHOD hooks as this is
a property of the transport. Notably, read_state may fail. In DTLS
check the handshake buffer size. We could place this check in
read_change_cipher_spec, but TLS 1.3 has no ChangeCipherSpec message, so
we will need to implement this at the cipher change point anyway. (For
now, there is only an assert on the TLS side. This will be replaced with
a proper check in TLS 1.3.)

Change-Id: Ia52b0b81e7db53e9ed2d4f6d334a1cce13e93297
Reviewed-on: https://boringssl-review.googlesource.com/8790
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
2016-07-16 08:25:02 +00:00

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/*
* DTLS implementation written by Nagendra Modadugu
* (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
*/
/* ====================================================================
* Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.] */
#include <openssl/ssl.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <openssl/buf.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include <openssl/x509.h>
#include "internal.h"
/* TODO(davidben): 28 comes from the size of IP + UDP header. Is this reasonable
* for these values? Notably, why is kMinMTU a function of the transport
* protocol's overhead rather than, say, what's needed to hold a minimally-sized
* handshake fragment plus protocol overhead. */
/* kMinMTU is the minimum acceptable MTU value. */
static const unsigned int kMinMTU = 256 - 28;
/* kDefaultMTU is the default MTU value to use if neither the user nor
* the underlying BIO supplies one. */
static const unsigned int kDefaultMTU = 1500 - 28;
/* Receiving handshake messages. */
static void dtls1_hm_fragment_free(hm_fragment *frag) {
if (frag == NULL) {
return;
}
OPENSSL_free(frag->data);
OPENSSL_free(frag->reassembly);
OPENSSL_free(frag);
}
static hm_fragment *dtls1_hm_fragment_new(const struct hm_header_st *msg_hdr) {
hm_fragment *frag = OPENSSL_malloc(sizeof(hm_fragment));
if (frag == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return NULL;
}
memset(frag, 0, sizeof(hm_fragment));
frag->type = msg_hdr->type;
frag->seq = msg_hdr->seq;
frag->msg_len = msg_hdr->msg_len;
/* Allocate space for the reassembled message and fill in the header. */
frag->data = OPENSSL_malloc(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len);
if (frag->data == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
CBB cbb;
if (!CBB_init_fixed(&cbb, frag->data, DTLS1_HM_HEADER_LENGTH) ||
!CBB_add_u8(&cbb, msg_hdr->type) ||
!CBB_add_u24(&cbb, msg_hdr->msg_len) ||
!CBB_add_u16(&cbb, msg_hdr->seq) ||
!CBB_add_u24(&cbb, 0 /* frag_off */) ||
!CBB_add_u24(&cbb, msg_hdr->msg_len) ||
!CBB_finish(&cbb, NULL, NULL)) {
CBB_cleanup(&cbb);
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
/* If the handshake message is empty, |frag->reassembly| is NULL. */
if (msg_hdr->msg_len > 0) {
/* Initialize reassembly bitmask. */
if (msg_hdr->msg_len + 7 < msg_hdr->msg_len) {
OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
goto err;
}
size_t bitmask_len = (msg_hdr->msg_len + 7) / 8;
frag->reassembly = OPENSSL_malloc(bitmask_len);
if (frag->reassembly == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
memset(frag->reassembly, 0, bitmask_len);
}
return frag;
err:
dtls1_hm_fragment_free(frag);
return NULL;
}
/* bit_range returns a |uint8_t| with bits |start|, inclusive, to |end|,
* exclusive, set. */
static uint8_t bit_range(size_t start, size_t end) {
return (uint8_t)(~((1u << start) - 1) & ((1u << end) - 1));
}
/* dtls1_hm_fragment_mark marks bytes |start|, inclusive, to |end|, exclusive,
* as received in |frag|. If |frag| becomes complete, it clears
* |frag->reassembly|. The range must be within the bounds of |frag|'s message
* and |frag->reassembly| must not be NULL. */
static void dtls1_hm_fragment_mark(hm_fragment *frag, size_t start,
size_t end) {
size_t i;
size_t msg_len = frag->msg_len;
if (frag->reassembly == NULL || start > end || end > msg_len) {
assert(0);
return;
}
/* A zero-length message will never have a pending reassembly. */
assert(msg_len > 0);
if ((start >> 3) == (end >> 3)) {
frag->reassembly[start >> 3] |= bit_range(start & 7, end & 7);
} else {
frag->reassembly[start >> 3] |= bit_range(start & 7, 8);
for (i = (start >> 3) + 1; i < (end >> 3); i++) {
frag->reassembly[i] = 0xff;
}
if ((end & 7) != 0) {
frag->reassembly[end >> 3] |= bit_range(0, end & 7);
}
}
/* Check if the fragment is complete. */
for (i = 0; i < (msg_len >> 3); i++) {
if (frag->reassembly[i] != 0xff) {
return;
}
}
if ((msg_len & 7) != 0 &&
frag->reassembly[msg_len >> 3] != bit_range(0, msg_len & 7)) {
return;
}
OPENSSL_free(frag->reassembly);
frag->reassembly = NULL;
}
/* dtls1_is_current_message_complete returns one if the current handshake
* message is complete and zero otherwise. */
static int dtls1_is_current_message_complete(const SSL *ssl) {
hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq %
SSL_MAX_HANDSHAKE_FLIGHT];
return frag != NULL && frag->reassembly == NULL;
}
/* dtls1_pop_message removes the current handshake message, which must be
* complete, and advances to the next one. */
static void dtls1_pop_message(SSL *ssl) {
assert(dtls1_is_current_message_complete(ssl));
size_t index = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT;
dtls1_hm_fragment_free(ssl->d1->incoming_messages[index]);
ssl->d1->incoming_messages[index] = NULL;
ssl->d1->handshake_read_seq++;
}
/* dtls1_get_incoming_message returns the incoming message corresponding to
* |msg_hdr|. If none exists, it creates a new one and inserts it in the
* queue. Otherwise, it checks |msg_hdr| is consistent with the existing one. It
* returns NULL on failure. The caller does not take ownership of the result. */
static hm_fragment *dtls1_get_incoming_message(
SSL *ssl, const struct hm_header_st *msg_hdr) {
if (msg_hdr->seq < ssl->d1->handshake_read_seq ||
msg_hdr->seq - ssl->d1->handshake_read_seq >= SSL_MAX_HANDSHAKE_FLIGHT) {
return NULL;
}
size_t idx = msg_hdr->seq % SSL_MAX_HANDSHAKE_FLIGHT;
hm_fragment *frag = ssl->d1->incoming_messages[idx];
if (frag != NULL) {
assert(frag->seq == msg_hdr->seq);
/* The new fragment must be compatible with the previous fragments from this
* message. */
if (frag->type != msg_hdr->type ||
frag->msg_len != msg_hdr->msg_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_FRAGMENT_MISMATCH);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return NULL;
}
return frag;
}
/* This is the first fragment from this message. */
frag = dtls1_hm_fragment_new(msg_hdr);
if (frag == NULL) {
return NULL;
}
ssl->d1->incoming_messages[idx] = frag;
return frag;
}
/* dtls1_process_handshake_record reads a handshake record and processes it. It
* returns one if the record was successfully processed and 0 or -1 on error. */
static int dtls1_process_handshake_record(SSL *ssl) {
SSL3_RECORD *rr = &ssl->s3->rrec;
start:
if (rr->length == 0) {
int ret = dtls1_get_record(ssl);
if (ret <= 0) {
return ret;
}
}
/* Cross-epoch records are discarded, but we may receive out-of-order
* application data between ChangeCipherSpec and Finished or a ChangeCipherSpec
* before the appropriate point in the handshake. Those must be silently
* discarded.
*
* However, only allow the out-of-order records in the correct epoch.
* Application data must come in the encrypted epoch, and ChangeCipherSpec in
* the unencrypted epoch (we never renegotiate). Other cases fall through and
* fail with a fatal error. */
if ((rr->type == SSL3_RT_APPLICATION_DATA &&
ssl->s3->aead_read_ctx != NULL) ||
(rr->type == SSL3_RT_CHANGE_CIPHER_SPEC &&
ssl->s3->aead_read_ctx == NULL)) {
rr->length = 0;
goto start;
}
if (rr->type != SSL3_RT_HANDSHAKE) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD);
return -1;
}
CBS cbs;
CBS_init(&cbs, rr->data, rr->length);
while (CBS_len(&cbs) > 0) {
/* Read a handshake fragment. */
struct hm_header_st msg_hdr;
CBS body;
if (!dtls1_parse_fragment(&cbs, &msg_hdr, &body)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HANDSHAKE_RECORD);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return -1;
}
const size_t frag_off = msg_hdr.frag_off;
const size_t frag_len = msg_hdr.frag_len;
const size_t msg_len = msg_hdr.msg_len;
if (frag_off > msg_len || frag_off + frag_len < frag_off ||
frag_off + frag_len > msg_len ||
msg_len > ssl_max_handshake_message_len(ssl)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return -1;
}
if (msg_hdr.seq < ssl->d1->handshake_read_seq ||
msg_hdr.seq >
(unsigned)ssl->d1->handshake_read_seq + SSL_MAX_HANDSHAKE_FLIGHT) {
/* Ignore fragments from the past, or ones too far in the future. */
continue;
}
hm_fragment *frag = dtls1_get_incoming_message(ssl, &msg_hdr);
if (frag == NULL) {
return -1;
}
assert(frag->msg_len == msg_len);
if (frag->reassembly == NULL) {
/* The message is already assembled. */
continue;
}
assert(msg_len > 0);
/* Copy the body into the fragment. */
memcpy(frag->data + DTLS1_HM_HEADER_LENGTH + frag_off, CBS_data(&body),
CBS_len(&body));
dtls1_hm_fragment_mark(frag, frag_off, frag_off + frag_len);
}
rr->length = 0;
ssl_read_buffer_discard(ssl);
return 1;
}
int dtls1_get_message(SSL *ssl, int msg_type,
enum ssl_hash_message_t hash_message) {
if (ssl->s3->tmp.reuse_message) {
/* A ssl_dont_hash_message call cannot be combined with reuse_message; the
* ssl_dont_hash_message would have to have been applied to the previous
* call. */
assert(hash_message == ssl_hash_message);
assert(dtls1_is_current_message_complete(ssl));
ssl->s3->tmp.reuse_message = 0;
hash_message = ssl_dont_hash_message;
} else if (dtls1_is_current_message_complete(ssl)) {
dtls1_pop_message(ssl);
}
/* Process handshake records until the current message is ready. */
while (!dtls1_is_current_message_complete(ssl)) {
int ret = dtls1_process_handshake_record(ssl);
if (ret <= 0) {
return ret;
}
}
hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq %
SSL_MAX_HANDSHAKE_FLIGHT];
assert(frag != NULL);
assert(frag->reassembly == NULL);
assert(ssl->d1->handshake_read_seq == frag->seq);
/* TODO(davidben): This function has a lot of implicit outputs. Simplify the
* |ssl_get_message| API. */
ssl->s3->tmp.message_type = frag->type;
ssl->init_msg = frag->data + DTLS1_HM_HEADER_LENGTH;
ssl->init_num = frag->msg_len;
if (msg_type >= 0 && ssl->s3->tmp.message_type != msg_type) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
return -1;
}
if (hash_message == ssl_hash_message && !dtls1_hash_current_message(ssl)) {
return -1;
}
ssl_do_msg_callback(ssl, 0 /* read */, ssl->version, SSL3_RT_HANDSHAKE,
frag->data, ssl->init_num + DTLS1_HM_HEADER_LENGTH);
return 1;
}
int dtls1_hash_current_message(SSL *ssl) {
assert(dtls1_is_current_message_complete(ssl));
hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq %
SSL_MAX_HANDSHAKE_FLIGHT];
return ssl3_update_handshake_hash(ssl, frag->data,
DTLS1_HM_HEADER_LENGTH + frag->msg_len);
}
void dtls_clear_incoming_messages(SSL *ssl) {
for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) {
dtls1_hm_fragment_free(ssl->d1->incoming_messages[i]);
ssl->d1->incoming_messages[i] = NULL;
}
}
int dtls_has_incoming_messages(const SSL *ssl) {
/* This function may not be called if there is a pending |dtls1_get_message|
* operation. */
assert(dtls1_is_current_message_complete(ssl));
size_t current = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT;
for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) {
if (i != current && ssl->d1->incoming_messages[i] != NULL) {
return 1;
}
}
return 0;
}
int dtls1_parse_fragment(CBS *cbs, struct hm_header_st *out_hdr,
CBS *out_body) {
memset(out_hdr, 0x00, sizeof(struct hm_header_st));
if (!CBS_get_u8(cbs, &out_hdr->type) ||
!CBS_get_u24(cbs, &out_hdr->msg_len) ||
!CBS_get_u16(cbs, &out_hdr->seq) ||
!CBS_get_u24(cbs, &out_hdr->frag_off) ||
!CBS_get_u24(cbs, &out_hdr->frag_len) ||
!CBS_get_bytes(cbs, out_body, out_hdr->frag_len)) {
return 0;
}
return 1;
}
/* Sending handshake messages. */
static void dtls1_update_mtu(SSL *ssl) {
/* TODO(davidben): What is this code doing and do we need it? */
if (ssl->d1->mtu < dtls1_min_mtu() &&
!(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
long mtu = BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) {
ssl->d1->mtu = (unsigned)mtu;
} else {
ssl->d1->mtu = kDefaultMTU;
BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_SET_MTU, ssl->d1->mtu, NULL);
}
}
/* The MTU should be above the minimum now. */
assert(ssl->d1->mtu >= dtls1_min_mtu());
}
/* dtls1_max_record_size returns the maximum record body length that may be
* written without exceeding the MTU. It accounts for any buffering installed on
* the write BIO. If no record may be written, it returns zero. */
static size_t dtls1_max_record_size(SSL *ssl) {
size_t ret = ssl->d1->mtu;
size_t overhead = ssl_max_seal_overhead(ssl);
if (ret <= overhead) {
return 0;
}
ret -= overhead;
size_t pending = BIO_wpending(ssl->wbio);
if (ret <= pending) {
return 0;
}
ret -= pending;
return ret;
}
static int dtls1_write_change_cipher_spec(SSL *ssl,
enum dtls1_use_epoch_t use_epoch) {
dtls1_update_mtu(ssl);
/* During the handshake, wbio is buffered to pack messages together. Flush the
* buffer if the ChangeCipherSpec would not fit in a packet. */
if (dtls1_max_record_size(ssl) == 0) {
int ret = BIO_flush(ssl->wbio);
if (ret <= 0) {
ssl->rwstate = SSL_WRITING;
return ret;
}
}
static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS};
int ret =
dtls1_write_record(ssl, SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec,
sizeof(kChangeCipherSpec), use_epoch);
if (ret <= 0) {
return ret;
}
ssl_do_msg_callback(ssl, 1 /* write */, ssl->version,
SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec,
sizeof(kChangeCipherSpec));
return 1;
}
/* dtls1_do_handshake_write writes handshake message |in| using the given epoch,
* starting |offset| bytes into the message body. It returns one on success. On
* error, it returns <= 0 and sets |*out_offset| to the number of bytes of body
* that were successfully written. This may be used to retry the write
* later. |in| must be a reassembled handshake message with the full DTLS
* handshake header. */
static int dtls1_do_handshake_write(SSL *ssl, size_t *out_offset,
const uint8_t *in, size_t offset,
size_t len,
enum dtls1_use_epoch_t use_epoch) {
dtls1_update_mtu(ssl);
int ret = -1;
CBB cbb;
CBB_zero(&cbb);
/* Allocate a temporary buffer to hold the message fragments to avoid
* clobbering the message. */
uint8_t *buf = OPENSSL_malloc(ssl->d1->mtu);
if (buf == NULL) {
goto err;
}
/* Although it may be sent as multiple fragments, a DTLS message must be sent
* serialized as a single fragment for purposes of |ssl_do_msg_callback| and
* the handshake hash. */
CBS cbs, body;
struct hm_header_st hdr;
CBS_init(&cbs, in, len);
if (!dtls1_parse_fragment(&cbs, &hdr, &body) ||
hdr.frag_off != 0 ||
hdr.frag_len != CBS_len(&body) ||
hdr.msg_len != CBS_len(&body) ||
!CBS_skip(&body, offset) ||
CBS_len(&cbs) != 0) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
goto err;
}
do {
/* During the handshake, wbio is buffered to pack messages together. Flush
* the buffer if there isn't enough room to make progress. */
if (dtls1_max_record_size(ssl) < DTLS1_HM_HEADER_LENGTH + 1) {
int flush_ret = BIO_flush(ssl->wbio);
if (flush_ret <= 0) {
ssl->rwstate = SSL_WRITING;
ret = flush_ret;
goto err;
}
assert(BIO_wpending(ssl->wbio) == 0);
}
size_t todo = dtls1_max_record_size(ssl);
if (todo < DTLS1_HM_HEADER_LENGTH + 1) {
/* To make forward progress, the MTU must, at minimum, fit the handshake
* header and one byte of handshake body. */
OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL);
goto err;
}
todo -= DTLS1_HM_HEADER_LENGTH;
if (todo > CBS_len(&body)) {
todo = CBS_len(&body);
}
if (todo >= (1u << 24)) {
todo = (1u << 24) - 1;
}
size_t buf_len;
if (!CBB_init_fixed(&cbb, buf, ssl->d1->mtu) ||
!CBB_add_u8(&cbb, hdr.type) ||
!CBB_add_u24(&cbb, hdr.msg_len) ||
!CBB_add_u16(&cbb, hdr.seq) ||
!CBB_add_u24(&cbb, offset) ||
!CBB_add_u24(&cbb, todo) ||
!CBB_add_bytes(&cbb, CBS_data(&body), todo) ||
!CBB_finish(&cbb, NULL, &buf_len)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
goto err;
}
int write_ret =
dtls1_write_record(ssl, SSL3_RT_HANDSHAKE, buf, buf_len, use_epoch);
if (write_ret <= 0) {
ret = write_ret;
goto err;
}
if (!CBS_skip(&body, todo)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
goto err;
}
offset += todo;
} while (CBS_len(&body) != 0);
ssl_do_msg_callback(ssl, 1 /* write */, ssl->version, SSL3_RT_HANDSHAKE, in,
len);
ret = 1;
err:
*out_offset = offset;
CBB_cleanup(&cbb);
OPENSSL_free(buf);
return ret;
}
void dtls_clear_outgoing_messages(SSL *ssl) {
size_t i;
for (i = 0; i < ssl->d1->outgoing_messages_len; i++) {
OPENSSL_free(ssl->d1->outgoing_messages[i].data);
ssl->d1->outgoing_messages[i].data = NULL;
}
ssl->d1->outgoing_messages_len = 0;
}
/* dtls1_add_change_cipher_spec adds a ChangeCipherSpec to the current
* handshake flight. */
static int dtls1_add_change_cipher_spec(SSL *ssl) {
if (ssl->d1->outgoing_messages_len >= SSL_MAX_HANDSHAKE_FLIGHT) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return 0;
}
DTLS_OUTGOING_MESSAGE *msg =
&ssl->d1->outgoing_messages[ssl->d1->outgoing_messages_len];
msg->data = NULL;
msg->len = 0;
msg->epoch = ssl->d1->w_epoch;
msg->is_ccs = 1;
ssl->d1->outgoing_messages_len++;
return 1;
}
static int dtls1_add_message(SSL *ssl, uint8_t *data, size_t len) {
if (ssl->d1->outgoing_messages_len >= SSL_MAX_HANDSHAKE_FLIGHT) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
OPENSSL_free(data);
return 0;
}
DTLS_OUTGOING_MESSAGE *msg =
&ssl->d1->outgoing_messages[ssl->d1->outgoing_messages_len];
msg->data = data;
msg->len = len;
msg->epoch = ssl->d1->w_epoch;
msg->is_ccs = 0;
ssl->d1->outgoing_messages_len++;
return 1;
}
int dtls1_init_message(SSL *ssl, CBB *cbb, CBB *body, uint8_t type) {
/* Pick a modest size hint to save most of the |realloc| calls. */
if (!CBB_init(cbb, 64) ||
!CBB_add_u8(cbb, type) ||
!CBB_add_u24(cbb, 0 /* length (filled in later) */) ||
!CBB_add_u16(cbb, ssl->d1->handshake_write_seq) ||
!CBB_add_u24(cbb, 0 /* offset */) ||
!CBB_add_u24_length_prefixed(cbb, body)) {
return 0;
}
return 1;
}
int dtls1_finish_message(SSL *ssl, CBB *cbb) {
uint8_t *msg = NULL;
size_t len;
if (!CBB_finish(cbb, &msg, &len) ||
len > 0xffffffffu ||
len < DTLS1_HM_HEADER_LENGTH) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
OPENSSL_free(msg);
return 0;
}
/* Fix up the header. Copy the fragment length into the total message
* length. */
memcpy(msg + 1, msg + DTLS1_HM_HEADER_LENGTH - 3, 3);
ssl3_update_handshake_hash(ssl, msg, len);
ssl->d1->handshake_write_seq++;
ssl->init_off = 0;
return dtls1_add_message(ssl, msg, len);
}
int dtls1_write_message(SSL *ssl) {
if (ssl->d1->outgoing_messages_len == 0) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return -1;
}
const DTLS_OUTGOING_MESSAGE *msg =
&ssl->d1->outgoing_messages[ssl->d1->outgoing_messages_len - 1];
if (msg->is_ccs) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return -1;
}
size_t offset = ssl->init_off;
int ret = dtls1_do_handshake_write(ssl, &offset, msg->data, offset, msg->len,
dtls1_use_current_epoch);
ssl->init_off = offset;
return ret;
}
static int dtls1_retransmit_message(SSL *ssl,
const DTLS_OUTGOING_MESSAGE *msg) {
/* DTLS renegotiation is unsupported, so only epochs 0 (NULL cipher) and 1
* (negotiated cipher) exist. */
assert(ssl->d1->w_epoch == 0 || ssl->d1->w_epoch == 1);
assert(msg->epoch <= ssl->d1->w_epoch);
enum dtls1_use_epoch_t use_epoch = dtls1_use_current_epoch;
if (ssl->d1->w_epoch == 1 && msg->epoch == 0) {
use_epoch = dtls1_use_previous_epoch;
}
/* TODO(davidben): This cannot handle non-blocking writes. */
int ret;
if (msg->is_ccs) {
ret = dtls1_write_change_cipher_spec(ssl, use_epoch);
} else {
size_t offset = 0;
ret = dtls1_do_handshake_write(ssl, &offset, msg->data, offset, msg->len,
use_epoch);
}
return ret;
}
int dtls1_retransmit_outgoing_messages(SSL *ssl) {
/* Ensure we are packing handshake messages. */
const int was_buffered = ssl_is_wbio_buffered(ssl);
assert(was_buffered == SSL_in_init(ssl));
if (!was_buffered && !ssl_init_wbio_buffer(ssl)) {
return -1;
}
assert(ssl_is_wbio_buffered(ssl));
int ret = -1;
size_t i;
for (i = 0; i < ssl->d1->outgoing_messages_len; i++) {
if (dtls1_retransmit_message(ssl, &ssl->d1->outgoing_messages[i]) <= 0) {
goto err;
}
}
ret = BIO_flush(ssl->wbio);
if (ret <= 0) {
ssl->rwstate = SSL_WRITING;
goto err;
}
err:
if (!was_buffered) {
ssl_free_wbio_buffer(ssl);
}
return ret;
}
int dtls1_send_change_cipher_spec(SSL *ssl) {
int ret = dtls1_write_change_cipher_spec(ssl, dtls1_use_current_epoch);
if (ret <= 0) {
return ret;
}
dtls1_add_change_cipher_spec(ssl);
return 1;
}
unsigned int dtls1_min_mtu(void) {
return kMinMTU;
}
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