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openssl/ssl/statem/statem_dtls.c

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/*
* Copyright 2005-2025 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (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 <assert.h>
#include <limits.h>
#include <string.h>
#include <stdio.h>
#include "../ssl_local.h"
#include "statem_local.h"
#include "internal/cryptlib.h"
#include "internal/ssl_unwrap.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; \
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 const unsigned char bitmask_start_values[] = {
0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80
};
static const unsigned char bitmask_end_values[] = {
0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f
};
static void dtls1_fix_message_header(SSL_CONNECTION *s, size_t frag_off,
size_t frag_len);
static unsigned char *dtls1_write_message_header(SSL_CONNECTION *s,
unsigned char *p);
static void dtls1_set_message_header_int(SSL_CONNECTION *s, unsigned char mt,
size_t len,
unsigned short seq_num,
size_t frag_off,
size_t frag_len);
static int dtls_get_reassembled_message(SSL_CONNECTION *s, int *errtype,
size_t *len);
static hm_fragment *dtls1_hm_fragment_new(size_t frag_len, int reassembly)
{
hm_fragment *frag = NULL;
unsigned char *buf = NULL;
unsigned char *bitmask = NULL;
if ((frag = OPENSSL_zalloc(sizeof(*frag))) == NULL)
return NULL;
if (frag_len) {
if ((buf = OPENSSL_malloc(frag_len)) == 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;
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_CONNECTION *s, uint8_t type)
{
int ret;
size_t written;
size_t curr_mtu;
int retry = 1;
size_t len, frag_off, overhead, used_len;
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
SSL *ussl = SSL_CONNECTION_GET_USER_SSL(s);
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) {
if (!ossl_assert(s->init_num ==
s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH))
return -1;
}
overhead = s->rlayer.wrlmethod->get_max_record_overhead(s->rlayer.wrl);
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) + overhead;
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;
}
if (s->d1->mtu > overhead + DTLS1_HM_HEADER_LENGTH) {
curr_mtu = s->d1->mtu - overhead;
} 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 > ssl_get_max_send_fragment(s))
len = ssl_get_max_send_fragment(s);
/*
* 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,
&written);
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(ssl),
BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0) {
if (!(SSL_get_options(ssl) & 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?
*/
if (!ossl_assert(len == written))
return -1;
/*
* We should not exceed the MTU size. If compression is in use
* then the max record overhead calculation is unreliable so we do
* not check in that case. We use assert rather than ossl_assert
* because in a production build, if this assert were ever to fail,
* then the best thing to do is probably carry on regardless.
*/
assert(s->s3.tmp.new_compression != NULL
|| BIO_wpending(s->wbio) <= (int)s->d1->mtu);
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;
size_t 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 = written;
} else {
p += DTLS1_HM_HEADER_LENGTH;
xlen = written - DTLS1_HM_HEADER_LENGTH;
}
if (!ssl3_finish_mac(s, p, xlen))
return -1;
}
if (written == 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), ussl,
s->msg_callback_arg);
s->init_off = 0; /* done writing this message */
s->init_num = 0;
return 1;
}
s->init_off += written;
s->init_num -= written;
written -= DTLS1_HM_HEADER_LENGTH;
frag_off += written;
/*
* 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_CONNECTION *s, int *mt)
{
struct hm_header_st *msg_hdr;
unsigned char *p;
size_t msg_len;
size_t tmplen;
int errtype;
msg_hdr = &s->d1->r_msg_hdr;
memset(msg_hdr, 0, sizeof(*msg_hdr));
again:
if (!dtls_get_reassembled_message(s, &errtype, &tmplen)) {
if (errtype == DTLS1_HM_BAD_FRAGMENT
|| errtype == DTLS1_HM_FRAGMENT_RETRY) {
/* bad fragment received */
goto again;
}
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, SSL_CONNECTION_GET_USER_SSL(s),
s->msg_callback_arg);
}
/*
* This isn't a real handshake message so skip the processing below.
*/
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);
memset(msg_hdr, 0, sizeof(*msg_hdr));
s->d1->handshake_read_seq++;
s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
return 1;
}
/*
* Actually we already have the message body - but this is an opportunity for
* DTLS to do any further processing it wants at the same point that TLS would
* be asked for the message body.
*/
int dtls_get_message_body(SSL_CONNECTION *s, size_t *len)
{
unsigned char *msg = (unsigned char *)s->init_buf->data;
size_t msg_len = s->init_num + DTLS1_HM_HEADER_LENGTH;
if (s->s3.tmp.message_type == SSL3_MT_CHANGE_CIPHER_SPEC) {
/* Nothing to be done */
goto end;
}
/*
* If receiving Finished, record MAC of prior handshake messages for
* Finished verification.
*/
if (*(s->init_buf->data) == SSL3_MT_FINISHED && !ssl3_take_mac(s)) {
/* SSLfatal() already called */
return 0;
}
if (s->version == DTLS1_BAD_VER) {
msg += DTLS1_HM_HEADER_LENGTH;
msg_len -= DTLS1_HM_HEADER_LENGTH;
}
if (!ssl3_finish_mac(s, msg, msg_len))
return 0;
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
s->init_buf->data, s->init_num + DTLS1_HM_HEADER_LENGTH,
SSL_CONNECTION_GET_USER_SSL(s), s->msg_callback_arg);
end:
*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 size_t dtls1_max_handshake_message_len(const SSL_CONNECTION *s)
{
size_t max_len = DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;
if (max_len < s->max_cert_list)
return s->max_cert_list;
return max_len;
}
static int dtls1_preprocess_fragment(SSL_CONNECTION *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)) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_R_EXCESSIVE_MESSAGE_SIZE);
return 0;
}
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)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_BUF_LIB);
return 0;
}
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.
*/
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_R_EXCESSIVE_MESSAGE_SIZE);
return 0;
}
return 1;
}
/*
* Returns 1 if there is a buffered fragment available, 0 if not, or -1 on a
* fatal error.
*/
static int dtls1_retrieve_buffered_fragment(SSL_CONNECTION *s, size_t *len)
{
/*-
* (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;
piterator iter;
hm_fragment *frag;
int ret;
int chretran = 0;
iter = pqueue_iterator(s->d1->buffered_messages);
do {
item = pqueue_next(&iter);
if (item == NULL)
return 0;
frag = (hm_fragment *)item->data;
if (frag->msg_header.seq < s->d1->handshake_read_seq) {
pitem *next;
hm_fragment *nextfrag;
if (!s->server
|| frag->msg_header.seq != 0
|| s->d1->handshake_read_seq != 1
|| s->statem.hand_state != DTLS_ST_SW_HELLO_VERIFY_REQUEST) {
/*
* This is a stale message that has been buffered so clear it.
* It is safe to pop this message from the queue even though
* we have an active iterator
*/
pqueue_pop(s->d1->buffered_messages);
dtls1_hm_fragment_free(frag);
pitem_free(item);
item = NULL;
frag = NULL;
} else {
/*
* We have fragments for a ClientHello without a cookie,
* even though we have sent a HelloVerifyRequest. It is possible
* that the HelloVerifyRequest got lost and this is a
* retransmission of the original ClientHello
*/
next = pqueue_next(&iter);
if (next != NULL) {
nextfrag = (hm_fragment *)next->data;
if (nextfrag->msg_header.seq == s->d1->handshake_read_seq) {
/*
* We have fragments for both a ClientHello without
* cookie and one with. Ditch the one without.
*/
pqueue_pop(s->d1->buffered_messages);
dtls1_hm_fragment_free(frag);
pitem_free(item);
item = next;
frag = nextfrag;
} else {
chretran = 1;
}
} else {
chretran = 1;
}
}
}
} 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 || chretran) {
size_t frag_len = frag->msg_header.frag_len;
pqueue_pop(s->d1->buffered_messages);
/* Calls SSLfatal() as required */
ret = dtls1_preprocess_fragment(s, &frag->msg_header);
if (ret && frag->msg_header.frag_len > 0) {
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 (ret) {
if (chretran) {
/*
* We got a new ClientHello with a message sequence of 0.
* Reset the read/write sequences back to the beginning.
* We process it like this is the first time we've seen a
* ClientHello from the client.
*/
s->d1->handshake_read_seq = 0;
s->d1->next_handshake_write_seq = 0;
}
*len = frag_len;
return 1;
}
/* Fatal error */
s->init_num = 0;
return -1;
} else {
return 0;
}
}
static int dtls1_reassemble_fragment(SSL_CONNECTION *s,
const struct hm_header_st *msg_hdr)
{
hm_fragment *frag = NULL;
pitem *item = NULL;
int i = -1, is_complete;
unsigned char seq64be[8];
size_t frag_len = msg_hdr->frag_len;
size_t readbytes;
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
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 = ssl->method->ssl_read_bytes(ssl, SSL3_RT_HANDSHAKE, NULL,
devnull,
frag_len >
sizeof(devnull) ? sizeof(devnull) :
frag_len, 0, &readbytes);
if (i <= 0)
goto err;
frag_len -= readbytes;
}
return DTLS1_HM_FRAGMENT_RETRY;
}
/* read the body of the fragment (header has already been read */
i = ssl->method->ssl_read_bytes(ssl, SSL3_RT_HANDSHAKE, NULL,
frag->fragment + msg_hdr->frag_off,
frag_len, 0, &readbytes);
if (i <= 0 || readbytes != 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));
if (!ossl_assert(msg_hdr->msg_len > 0))
goto err;
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.
*/
if (!ossl_assert(item != NULL))
goto err;
}
return DTLS1_HM_FRAGMENT_RETRY;
err:
if (item == NULL)
dtls1_hm_fragment_free(frag);
return -1;
}
static int dtls1_process_out_of_seq_message(SSL_CONNECTION *s,
const struct hm_header_st *msg_hdr)
{
int i = -1;
hm_fragment *frag = NULL;
pitem *item = NULL;
unsigned char seq64be[8];
size_t frag_len = msg_hdr->frag_len;
size_t readbytes;
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
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 = ssl->method->ssl_read_bytes(ssl, SSL3_RT_HANDSHAKE, NULL,
devnull,
frag_len >
sizeof(devnull) ? sizeof(devnull) :
frag_len, 0, &readbytes);
if (i <= 0)
goto err;
frag_len -= readbytes;
}
} else {
if (frag_len != msg_hdr->msg_len) {
return dtls1_reassemble_fragment(s, msg_hdr);
}
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 = ssl->method->ssl_read_bytes(ssl, SSL3_RT_HANDSHAKE, NULL,
frag->fragment, frag_len, 0,
&readbytes);
if (i<=0 || readbytes != 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.
*/
if (!ossl_assert(item != NULL))
goto err;
}
return DTLS1_HM_FRAGMENT_RETRY;
err:
if (item == NULL)
dtls1_hm_fragment_free(frag);
return 0;
}
static int dtls_get_reassembled_message(SSL_CONNECTION *s, int *errtype,
size_t *len)
{
size_t mlen, frag_off, frag_len;
int i, ret;
uint8_t recvd_type;
struct hm_header_st msg_hdr;
size_t readbytes;
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
SSL *ussl = SSL_CONNECTION_GET_USER_SSL(s);
int chretran = 0;
unsigned char *p;
*errtype = 0;
p = (unsigned char *)s->init_buf->data;
redo:
/* see if we have the required fragment already */
ret = dtls1_retrieve_buffered_fragment(s, &frag_len);
if (ret < 0) {
/* SSLfatal() already called */
return 0;
}
if (ret > 0) {
s->init_num = frag_len;
*len = frag_len;
return 1;
}
/* read handshake message header */
i = ssl->method->ssl_read_bytes(ssl, SSL3_RT_HANDSHAKE, &recvd_type, p,
DTLS1_HM_HEADER_LENGTH, 0, &readbytes);
if (i <= 0) { /* nbio, or an error */
s->rwstate = SSL_READING;
*len = 0;
return 0;
}
if (recvd_type == SSL3_RT_CHANGE_CIPHER_SPEC) {
if (p[0] != SSL3_MT_CCS) {
SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
SSL_R_BAD_CHANGE_CIPHER_SPEC);
goto f_err;
}
s->init_num = readbytes - 1;
s->init_msg = s->init_buf->data + 1;
s->s3.tmp.message_type = SSL3_MT_CHANGE_CIPHER_SPEC;
s->s3.tmp.message_size = readbytes - 1;
*len = readbytes - 1;
return 1;
}
/* Handshake fails if message header is incomplete */
if (readbytes != DTLS1_HM_HEADER_LENGTH) {
SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
goto f_err;
}
/* parse the message fragment header */
dtls1_get_message_header(p, &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 > s->rlayer.tlsrecs[s->rlayer.curr_rec].length) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, 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) {
if (!s->server
|| msg_hdr.seq != 0
|| s->d1->handshake_read_seq != 1
|| p[0] != SSL3_MT_CLIENT_HELLO
|| s->statem.hand_state != DTLS_ST_SW_HELLO_VERIFY_REQUEST) {
*errtype = dtls1_process_out_of_seq_message(s, &msg_hdr);
return 0;
}
/*
* We received a ClientHello and sent back a HelloVerifyRequest. We
* now seem to have received a retransmitted initial ClientHello. That
* is allowed (possibly our HelloVerifyRequest got lost).
*/
chretran = 1;
}
if (frag_len && frag_len < mlen) {
*errtype = dtls1_reassemble_fragment(s, &msg_hdr);
return 0;
}
if (!s->server
&& s->d1->r_msg_hdr.frag_off == 0
&& s->statem.hand_state != TLS_ST_OK
&& p[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 (p[1] == 0 && p[2] == 0 && p[3] == 0) {
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
p, DTLS1_HM_HEADER_LENGTH, ussl,
s->msg_callback_arg);
s->init_num = 0;
goto redo;
} else { /* Incorrectly formatted Hello request */
SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
goto f_err;
}
}
if (!dtls1_preprocess_fragment(s, &msg_hdr)) {
/* SSLfatal() already called */
goto f_err;
}
if (frag_len > 0) {
p += DTLS1_HM_HEADER_LENGTH;
i = ssl->method->ssl_read_bytes(ssl, SSL3_RT_HANDSHAKE, NULL,
&p[frag_off], frag_len, 0, &readbytes);
/*
* 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 = 0;
return 0;
}
} else {
readbytes = 0;
}
/*
* XDTLS: an incorrectly formatted fragment should cause the handshake
* to fail
*/
if (readbytes != frag_len) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_R_BAD_LENGTH);
goto f_err;
}
if (chretran) {
/*
* We got a new ClientHello with a message sequence of 0.
* Reset the read/write sequences back to the beginning.
* We process it like this is the first time we've seen a ClientHello
* from the client.
*/
s->d1->handshake_read_seq = 0;
s->d1->next_handshake_write_seq = 0;
}
/*
* 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:
s->init_num = 0;
*len = 0;
return 0;
}
/*-
* for these 2 messages, we need to
* ssl->session->read_sym_enc assign
* ssl->session->read_compression assign
* ssl->session->read_hash assign
*/
CON_FUNC_RETURN dtls_construct_change_cipher_spec(SSL_CONNECTION *s,
WPACKET *pkt)
{
if (s->version == DTLS1_BAD_VER) {
s->d1->next_handshake_write_seq++;
if (!WPACKET_put_bytes_u16(pkt, s->d1->handshake_write_seq)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return CON_FUNC_ERROR;
}
}
return CON_FUNC_SUCCESS;
}
#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 an alert.
*/
WORK_STATE dtls_wait_for_dry(SSL_CONNECTION *s)
{
int ret, errtype;
size_t len;
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
/* read app data until dry event */
ret = BIO_dgram_sctp_wait_for_dry(SSL_get_wbio(ssl));
if (ret < 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
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, &errtype, &len)) {
/* The call succeeded! This should never happen */
SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
return WORK_ERROR;
}
s->s3.in_read_app_data = 2;
s->rwstate = SSL_READING;
BIO_clear_retry_flags(SSL_get_rbio(ssl));
BIO_set_retry_read(SSL_get_rbio(ssl));
return WORK_MORE_A;
}
return WORK_FINISHED_CONTINUE;
}
#endif
int dtls1_read_failed(SSL_CONNECTION *s, int code)
{
SSL *ssl = SSL_CONNECTION_GET_SSL(s);
if (code > 0) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return 0;
}
if (!dtls1_is_timer_expired(s) || ossl_statem_in_error(s)) {
/*
* not a timeout, none of our business, let higher layers handle
* this. in fact it's probably an error
*/
return code;
}
/* done, no need to send a retransmit */
if (!SSL_in_init(ssl)) {
BIO_set_flags(SSL_get_rbio(ssl), 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_CONNECTION *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_CONNECTION *s, int is_ccs)
{
pitem *item;
hm_fragment *frag;
unsigned char seq64be[8];
/*
* this function is called immediately after a message has been
* serialized
*/
if (!ossl_assert(s->init_off == 0))
return 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 */
if (!ossl_assert(s->d1->w_msg_hdr.msg_len +
((s->version ==
DTLS1_BAD_VER) ? 3 : DTLS1_CCS_HEADER_LENGTH)
== (unsigned int)s->init_num)) {
dtls1_hm_fragment_free(frag);
return 0;
}
} else {
if (!ossl_assert(s->d1->w_msg_hdr.msg_len +
DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num)) {
dtls1_hm_fragment_free(frag);
return 0;
}
}
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.wrlmethod = s->rlayer.wrlmethod;
frag->msg_header.saved_retransmit_state.wrl = s->rlayer.wrl;
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_CONNECTION *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;
/* 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) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, 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.wrlmethod = s->rlayer.wrlmethod;
saved_state.wrl = s->rlayer.wrl;
s->d1->retransmitting = 1;
/* restore state in which the message was originally sent */
s->rlayer.wrlmethod = frag->msg_header.saved_retransmit_state.wrlmethod;
s->rlayer.wrl = frag->msg_header.saved_retransmit_state.wrl;
/*
* The old wrl may be still pointing at an old BIO. Update it to what we're
* using now.
*/
s->rlayer.wrlmethod->set1_bio(s->rlayer.wrl, s->wbio);
ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
/* restore current state */
s->rlayer.wrlmethod = saved_state.wrlmethod;
s->rlayer.wrl = saved_state.wrl;
s->d1->retransmitting = 0;
(void)BIO_flush(s->wbio);
return ret;
}
void dtls1_set_message_header(SSL_CONNECTION *s,
unsigned char mt, size_t len,
size_t frag_off, size_t 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_CONNECTION *s, unsigned char mt,
size_t len, unsigned short seq_num,
size_t frag_off, size_t 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_CONNECTION *s, size_t frag_off, size_t 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_CONNECTION *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(const 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);
}
int dtls1_set_handshake_header(SSL_CONNECTION *s, WPACKET *pkt, int htype)
{
unsigned char *header;
if (htype == SSL3_MT_CHANGE_CIPHER_SPEC) {
s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
s->d1->handshake_write_seq, 0, 0);
if (!WPACKET_put_bytes_u8(pkt, SSL3_MT_CCS))
return 0;
} else {
dtls1_set_message_header(s, htype, 0, 0, 0);
/*
* We allocate space at the start for the message header. This gets
* filled in later
*/
if (!WPACKET_allocate_bytes(pkt, DTLS1_HM_HEADER_LENGTH, &header)
|| !WPACKET_start_sub_packet(pkt))
return 0;
}
return 1;
}
int dtls1_close_construct_packet(SSL_CONNECTION *s, WPACKET *pkt, int htype)
{
size_t msglen;
if ((htype != SSL3_MT_CHANGE_CIPHER_SPEC && !WPACKET_close(pkt))
|| !WPACKET_get_length(pkt, &msglen)
|| msglen > INT_MAX)
return 0;
if (htype != SSL3_MT_CHANGE_CIPHER_SPEC) {
s->d1->w_msg_hdr.msg_len = msglen - DTLS1_HM_HEADER_LENGTH;
s->d1->w_msg_hdr.frag_len = msglen - DTLS1_HM_HEADER_LENGTH;
}
s->init_num = (int)msglen;
s->init_off = 0;
if (htype != DTLS1_MT_HELLO_VERIFY_REQUEST) {
/* Buffer the message to handle re-xmits */
if (!dtls1_buffer_message(s, htype == SSL3_MT_CHANGE_CIPHER_SPEC
? 1 : 0))
return 0;
}
return 1;
}
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