/*
* 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/type_check.h>
#include "../crypto/internal.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;
}
OPENSSL_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;
}
OPENSSL_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 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 (size_t 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 (size_t 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_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;
}
/* The encrypted epoch in DTLS has only one handshake message. */
if (ssl->d1->r_epoch == 1 && msg_hdr.seq != ssl->d1->handshake_read_seq) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
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. */
OPENSSL_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) {
if (ssl->s3->tmp.reuse_message) {
/* There must be a current message. */
assert(ssl->init_msg != NULL);
ssl->s3->tmp.reuse_message = 0;
} else {
dtls1_release_current_message(ssl, 0 /* don't free buffer */);
}
/* 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;
ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, frag->data,
ssl->init_num + DTLS1_HM_HEADER_LENGTH);
return 1;
}
void dtls1_get_current_message(const SSL *ssl, CBS *out) {
assert(dtls1_is_current_message_complete(ssl));
hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq %
SSL_MAX_HANDSHAKE_FLIGHT];
CBS_init(out, frag->data, DTLS1_HM_HEADER_LENGTH + frag->msg_len);
}
void dtls1_release_current_message(SSL *ssl, int free_buffer) {
if (ssl->init_msg == NULL) {
return;
}
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++;
ssl->init_msg = NULL;
ssl->init_num = 0;
}
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) {
size_t current = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT;
for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) {
/* Skip the current message. */
if (ssl->init_msg != NULL && i == current) {
assert(dtls1_is_current_message_complete(ssl));
continue;
}
if (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) {
OPENSSL_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. */
void dtls_clear_outgoing_messages(SSL *ssl) {
for (size_t 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;
ssl->d1->outgoing_written = 0;
ssl->d1->outgoing_offset = 0;
}
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 **out_msg,
size_t *out_len) {
*out_msg = NULL;
if (!CBB_finish(cbb, out_msg, out_len) ||
*out_len < DTLS1_HM_HEADER_LENGTH) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
OPENSSL_free(*out_msg);
return 0;
}
/* Fix up the header. Copy the fragment length into the total message
* length. */
OPENSSL_memcpy(*out_msg + 1, *out_msg + DTLS1_HM_HEADER_LENGTH - 3, 3);
return 1;
}
/* add_outgoing adds a new handshake message or ChangeCipherSpec to the current
* outgoing flight. It returns one on success and zero on error. In both cases,
* it takes ownership of |data| and releases it with |OPENSSL_free| when
* done. */
static int add_outgoing(SSL *ssl, int is_ccs, uint8_t *data, size_t len) {
OPENSSL_COMPILE_ASSERT(SSL_MAX_HANDSHAKE_FLIGHT <
(1 << 8 * sizeof(ssl->d1->outgoing_messages_len)),
outgoing_messages_len_is_too_small);
if (ssl->d1->outgoing_messages_len >= SSL_MAX_HANDSHAKE_FLIGHT) {
assert(0);
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
OPENSSL_free(data);
return 0;
}
if (!is_ccs) {
/* TODO(svaldez): Move this up a layer to fix abstraction for SSL_TRANSCRIPT
* on hs. */
if (ssl->s3->hs != NULL &&
!SSL_TRANSCRIPT_update(&ssl->s3->hs->transcript, data, len)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
OPENSSL_free(data);
return 0;
}
ssl->d1->handshake_write_seq++;
}
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 = is_ccs;
ssl->d1->outgoing_messages_len++;
return 1;
}
int dtls1_add_message(SSL *ssl, uint8_t *data, size_t len) {
return add_outgoing(ssl, 0 /* handshake */, data, len);
}
int dtls1_add_change_cipher_spec(SSL *ssl) {
return add_outgoing(ssl, 1 /* ChangeCipherSpec */, NULL, 0);
}
int dtls1_add_alert(SSL *ssl, uint8_t level, uint8_t desc) {
/* The |add_alert| path is only used for warning alerts for now, which DTLS
* never sends. This will be implemented later once closure alerts are
* converted. */
assert(0);
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return 0;
}
/* dtls1_update_mtu updates the current MTU from the BIO, ensuring it is above
* the minimum. */
static void dtls1_update_mtu(SSL *ssl) {
/* TODO(davidben): No consumer implements |BIO_CTRL_DGRAM_SET_MTU| and the
* only |BIO_CTRL_DGRAM_QUERY_MTU| implementation could use
* |SSL_set_mtu|. Does this need to be so complex? */
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());
}
enum seal_result_t {
seal_error,
seal_no_progress,
seal_partial,
seal_success,
};
/* seal_next_message seals |msg|, which must be the next message, to |out|. If
* progress was made, it returns |seal_partial| or |seal_success| and sets
* |*out_len| to the number of bytes written. */
static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out,
size_t *out_len, size_t max_out,
const DTLS_OUTGOING_MESSAGE *msg) {
assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len);
assert(msg == &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]);
/* 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;
}
size_t overhead = dtls_max_seal_overhead(ssl, use_epoch);
size_t prefix = dtls_seal_prefix_len(ssl, use_epoch);
if (msg->is_ccs) {
/* Check there is room for the ChangeCipherSpec. */
static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS};
if (max_out < sizeof(kChangeCipherSpec) + overhead) {
return seal_no_progress;
}
if (!dtls_seal_record(ssl, out, out_len, max_out,
SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec,
sizeof(kChangeCipherSpec), use_epoch)) {
return seal_error;
}
ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_CHANGE_CIPHER_SPEC,
kChangeCipherSpec, sizeof(kChangeCipherSpec));
return seal_success;
}
/* DTLS messages are serialized as a single fragment in |msg|. */
CBS cbs, body;
struct hm_header_st hdr;
CBS_init(&cbs, msg->data, msg->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, ssl->d1->outgoing_offset) ||
CBS_len(&cbs) != 0) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return seal_error;
}
/* Determine how much progress can be made. */
if (max_out < DTLS1_HM_HEADER_LENGTH + 1 + overhead || max_out < prefix) {
return seal_no_progress;
}
size_t todo = CBS_len(&body);
if (todo > max_out - DTLS1_HM_HEADER_LENGTH - overhead) {
todo = max_out - DTLS1_HM_HEADER_LENGTH - overhead;
}
/* Assemble a fragment, to be sealed in-place. */
CBB cbb;
uint8_t *frag = out + prefix;
size_t max_frag = max_out - prefix, frag_len;
if (!CBB_init_fixed(&cbb, frag, max_frag) ||
!CBB_add_u8(&cbb, hdr.type) ||
!CBB_add_u24(&cbb, hdr.msg_len) ||
!CBB_add_u16(&cbb, hdr.seq) ||
!CBB_add_u24(&cbb, ssl->d1->outgoing_offset) ||
!CBB_add_u24(&cbb, todo) ||
!CBB_add_bytes(&cbb, CBS_data(&body), todo) ||
!CBB_finish(&cbb, NULL, &frag_len)) {
CBB_cleanup(&cbb);
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return seal_error;
}
ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HANDSHAKE, frag, frag_len);
if (!dtls_seal_record(ssl, out, out_len, max_out, SSL3_RT_HANDSHAKE,
out + prefix, frag_len, use_epoch)) {
return seal_error;
}
if (todo == CBS_len(&body)) {
/* The next message is complete. */
ssl->d1->outgoing_offset = 0;
return seal_success;
}
ssl->d1->outgoing_offset += todo;
return seal_partial;
}
/* seal_next_packet writes as much of the next flight as possible to |out| and
* advances |ssl->d1->outgoing_written| and |ssl->d1->outgoing_offset| as
* appropriate. */
static int seal_next_packet(SSL *ssl, uint8_t *out, size_t *out_len,
size_t max_out) {
int made_progress = 0;
size_t total = 0;
assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len);
for (; ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len;
ssl->d1->outgoing_written++) {
const DTLS_OUTGOING_MESSAGE *msg =
&ssl->d1->outgoing_messages[ssl->d1->outgoing_written];
size_t len;
enum seal_result_t ret = seal_next_message(ssl, out, &len, max_out, msg);
switch (ret) {
case seal_error:
return 0;
case seal_no_progress:
goto packet_full;
case seal_partial:
case seal_success:
out += len;
max_out -= len;
total += len;
made_progress = 1;
if (ret == seal_partial) {
goto packet_full;
}
break;
}
}
packet_full:
/* The MTU was too small to make any progress. */
if (!made_progress) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL);
return 0;
}
*out_len = total;
return 1;
}
int dtls1_flush_flight(SSL *ssl) {
dtls1_update_mtu(ssl);
int ret = -1;
uint8_t *packet = OPENSSL_malloc(ssl->d1->mtu);
if (packet == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len) {
uint8_t old_written = ssl->d1->outgoing_written;
uint32_t old_offset = ssl->d1->outgoing_offset;
size_t packet_len;
if (!seal_next_packet(ssl, packet, &packet_len, ssl->d1->mtu)) {
goto err;
}
int bio_ret = BIO_write(ssl->wbio, packet, packet_len);
if (bio_ret <= 0) {
/* Retry this packet the next time around. */
ssl->d1->outgoing_written = old_written;
ssl->d1->outgoing_offset = old_offset;
ssl->rwstate = SSL_WRITING;
ret = bio_ret;
goto err;
}
}
if (BIO_flush(ssl->wbio) <= 0) {
ssl->rwstate = SSL_WRITING;
goto err;
}
ret = 1;
err:
OPENSSL_free(packet);
return ret;
}
int dtls1_retransmit_outgoing_messages(SSL *ssl) {
/* Rewind to the start of the flight and write it again.
*
* TODO(davidben): This does not allow retransmits to be resumed on
* non-blocking write. */
ssl->d1->outgoing_written = 0;
ssl->d1->outgoing_offset = 0;
return dtls1_flush_flight(ssl);
}
unsigned int dtls1_min_mtu(void) {
return kMinMTU;
}