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openssl/ssl/d1_lib.c
David Woodhouse 045bd04706 Add DTLS_get_data_mtu() function 
We add ssl_cipher_get_overhead() as an internal function, to avoid
having too much ciphersuite-specific knowledge in DTLS_get_data_mtu()
itself. It's going to need adjustment for TLSv1.3... but then again, so
is fairly much *all* of the SSL_CIPHER handling. This bit is in the noise.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
2016-11-02 14:00:10 +00:00

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/*
* Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (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 <stdio.h>
#define USE_SOCKETS
#include <openssl/objects.h>
#include <openssl/rand.h>
#include "ssl_locl.h"
#if defined(OPENSSL_SYS_VMS)
# include <sys/timeb.h>
#elif defined(OPENSSL_SYS_VXWORKS)
# include <sys/times.h>
#elif !defined(OPENSSL_SYS_WIN32)
# include <sys/time.h>
#endif
static void get_current_time(struct timeval *t);
static int dtls1_handshake_write(SSL *s);
static unsigned int dtls1_link_min_mtu(void);
/* XDTLS: figure out the right values */
static const unsigned int g_probable_mtu[] = { 1500, 512, 256 };
const SSL3_ENC_METHOD DTLSv1_enc_data = {
tls1_enc,
tls1_mac,
tls1_setup_key_block,
tls1_generate_master_secret,
tls1_change_cipher_state,
tls1_final_finish_mac,
TLS1_FINISH_MAC_LENGTH,
TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
tls1_alert_code,
tls1_export_keying_material,
SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV,
DTLS1_HM_HEADER_LENGTH,
dtls1_set_handshake_header,
dtls1_close_construct_packet,
dtls1_handshake_write
};
const SSL3_ENC_METHOD DTLSv1_2_enc_data = {
tls1_enc,
tls1_mac,
tls1_setup_key_block,
tls1_generate_master_secret,
tls1_change_cipher_state,
tls1_final_finish_mac,
TLS1_FINISH_MAC_LENGTH,
TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
tls1_alert_code,
tls1_export_keying_material,
SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS
| SSL_ENC_FLAG_SHA256_PRF | SSL_ENC_FLAG_TLS1_2_CIPHERS,
DTLS1_HM_HEADER_LENGTH,
dtls1_set_handshake_header,
dtls1_close_construct_packet,
dtls1_handshake_write
};
long dtls1_default_timeout(void)
{
/*
* 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for
* http, the cache would over fill
*/
return (60 * 60 * 2);
}
int dtls1_new(SSL *s)
{
DTLS1_STATE *d1;
if (!DTLS_RECORD_LAYER_new(&s->rlayer)) {
return 0;
}
if (!ssl3_new(s))
return (0);
if ((d1 = OPENSSL_zalloc(sizeof(*d1))) == NULL) {
ssl3_free(s);
return (0);
}
d1->buffered_messages = pqueue_new();
d1->sent_messages = pqueue_new();
if (s->server) {
d1->cookie_len = sizeof(s->d1->cookie);
}
d1->link_mtu = 0;
d1->mtu = 0;
if (d1->buffered_messages == NULL || d1->sent_messages == NULL) {
pqueue_free(d1->buffered_messages);
pqueue_free(d1->sent_messages);
OPENSSL_free(d1);
ssl3_free(s);
return (0);
}
s->d1 = d1;
s->method->ssl_clear(s);
return (1);
}
static void dtls1_clear_queues(SSL *s)
{
dtls1_clear_received_buffer(s);
dtls1_clear_sent_buffer(s);
}
void dtls1_clear_received_buffer(SSL *s)
{
pitem *item = NULL;
hm_fragment *frag = NULL;
while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
frag = (hm_fragment *)item->data;
dtls1_hm_fragment_free(frag);
pitem_free(item);
}
}
void dtls1_clear_sent_buffer(SSL *s)
{
pitem *item = NULL;
hm_fragment *frag = NULL;
while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
frag = (hm_fragment *)item->data;
dtls1_hm_fragment_free(frag);
pitem_free(item);
}
}
void dtls1_free(SSL *s)
{
DTLS_RECORD_LAYER_free(&s->rlayer);
ssl3_free(s);
dtls1_clear_queues(s);
pqueue_free(s->d1->buffered_messages);
pqueue_free(s->d1->sent_messages);
OPENSSL_free(s->d1);
s->d1 = NULL;
}
void dtls1_clear(SSL *s)
{
pqueue *buffered_messages;
pqueue *sent_messages;
unsigned int mtu;
unsigned int link_mtu;
DTLS_RECORD_LAYER_clear(&s->rlayer);
if (s->d1) {
buffered_messages = s->d1->buffered_messages;
sent_messages = s->d1->sent_messages;
mtu = s->d1->mtu;
link_mtu = s->d1->link_mtu;
dtls1_clear_queues(s);
memset(s->d1, 0, sizeof(*s->d1));
if (s->server) {
s->d1->cookie_len = sizeof(s->d1->cookie);
}
if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
s->d1->mtu = mtu;
s->d1->link_mtu = link_mtu;
}
s->d1->buffered_messages = buffered_messages;
s->d1->sent_messages = sent_messages;
}
ssl3_clear(s);
if (s->method->version == DTLS_ANY_VERSION)
s->version = DTLS_MAX_VERSION;
#ifndef OPENSSL_NO_DTLS1_METHOD
else if (s->options & SSL_OP_CISCO_ANYCONNECT)
s->client_version = s->version = DTLS1_BAD_VER;
#endif
else
s->version = s->method->version;
}
long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
{
int ret = 0;
switch (cmd) {
case DTLS_CTRL_GET_TIMEOUT:
if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
ret = 1;
}
break;
case DTLS_CTRL_HANDLE_TIMEOUT:
ret = dtls1_handle_timeout(s);
break;
case DTLS_CTRL_SET_LINK_MTU:
if (larg < (long)dtls1_link_min_mtu())
return 0;
s->d1->link_mtu = larg;
return 1;
case DTLS_CTRL_GET_LINK_MIN_MTU:
return (long)dtls1_link_min_mtu();
case SSL_CTRL_SET_MTU:
/*
* We may not have a BIO set yet so can't call dtls1_min_mtu()
* We'll have to make do with dtls1_link_min_mtu() and max overhead
*/
if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
return 0;
s->d1->mtu = larg;
return larg;
default:
ret = ssl3_ctrl(s, cmd, larg, parg);
break;
}
return (ret);
}
void dtls1_start_timer(SSL *s)
{
#ifndef OPENSSL_NO_SCTP
/* Disable timer for SCTP */
if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
return;
}
#endif
/* If timer is not set, initialize duration with 1 second */
if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
s->d1->timeout_duration = 1;
}
/* Set timeout to current time */
get_current_time(&(s->d1->next_timeout));
/* Add duration to current time */
s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
&(s->d1->next_timeout));
}
struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft)
{
struct timeval timenow;
/* If no timeout is set, just return NULL */
if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
return NULL;
}
/* Get current time */
get_current_time(&timenow);
/* If timer already expired, set remaining time to 0 */
if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
(s->d1->next_timeout.tv_sec == timenow.tv_sec &&
s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
memset(timeleft, 0, sizeof(*timeleft));
return timeleft;
}
/* Calculate time left until timer expires */
memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
timeleft->tv_sec -= timenow.tv_sec;
timeleft->tv_usec -= timenow.tv_usec;
if (timeleft->tv_usec < 0) {
timeleft->tv_sec--;
timeleft->tv_usec += 1000000;
}
/*
* If remaining time is less than 15 ms, set it to 0 to prevent issues
* because of small divergences with socket timeouts.
*/
if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
memset(timeleft, 0, sizeof(*timeleft));
}
return timeleft;
}
int dtls1_is_timer_expired(SSL *s)
{
struct timeval timeleft;
/* Get time left until timeout, return false if no timer running */
if (dtls1_get_timeout(s, &timeleft) == NULL) {
return 0;
}
/* Return false if timer is not expired yet */
if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
return 0;
}
/* Timer expired, so return true */
return 1;
}
void dtls1_double_timeout(SSL *s)
{
s->d1->timeout_duration *= 2;
if (s->d1->timeout_duration > 60)
s->d1->timeout_duration = 60;
dtls1_start_timer(s);
}
void dtls1_stop_timer(SSL *s)
{
/* Reset everything */
memset(&s->d1->timeout, 0, sizeof(s->d1->timeout));
memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
s->d1->timeout_duration = 1;
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
&(s->d1->next_timeout));
/* Clear retransmission buffer */
dtls1_clear_sent_buffer(s);
}
int dtls1_check_timeout_num(SSL *s)
{
unsigned int mtu;
s->d1->timeout.num_alerts++;
/* Reduce MTU after 2 unsuccessful retransmissions */
if (s->d1->timeout.num_alerts > 2
&& !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
mtu =
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
if (mtu < s->d1->mtu)
s->d1->mtu = mtu;
}
if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
/* fail the connection, enough alerts have been sent */
SSLerr(SSL_F_DTLS1_CHECK_TIMEOUT_NUM, SSL_R_READ_TIMEOUT_EXPIRED);
return -1;
}
return 0;
}
int dtls1_handle_timeout(SSL *s)
{
/* if no timer is expired, don't do anything */
if (!dtls1_is_timer_expired(s)) {
return 0;
}
dtls1_double_timeout(s);
if (dtls1_check_timeout_num(s) < 0)
return -1;
s->d1->timeout.read_timeouts++;
if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
s->d1->timeout.read_timeouts = 1;
}
#ifndef OPENSSL_NO_HEARTBEATS
if (s->tlsext_hb_pending) {
s->tlsext_hb_pending = 0;
return dtls1_heartbeat(s);
}
#endif
dtls1_start_timer(s);
return dtls1_retransmit_buffered_messages(s);
}
static void get_current_time(struct timeval *t)
{
#if defined(_WIN32)
SYSTEMTIME st;
union {
unsigned __int64 ul;
FILETIME ft;
} now;
GetSystemTime(&st);
SystemTimeToFileTime(&st, &now.ft);
/* re-bias to 1/1/1970 */
# ifdef __MINGW32__
now.ul -= 116444736000000000ULL;
# else
/* *INDENT-OFF* */
now.ul -= 116444736000000000UI64;
/* *INDENT-ON* */
# endif
t->tv_sec = (long)(now.ul / 10000000);
t->tv_usec = ((int)(now.ul % 10000000)) / 10;
#elif defined(OPENSSL_SYS_VMS)
struct timeb tb;
ftime(&tb);
t->tv_sec = (long)tb.time;
t->tv_usec = (long)tb.millitm * 1000;
#else
gettimeofday(t, NULL);
#endif
}
#define LISTEN_SUCCESS 2
#define LISTEN_SEND_VERIFY_REQUEST 1
#ifndef OPENSSL_NO_SOCK
int DTLSv1_listen(SSL *s, BIO_ADDR *client)
{
int next, n, ret = 0, clearpkt = 0;
unsigned char cookie[DTLS1_COOKIE_LENGTH];
unsigned char seq[SEQ_NUM_SIZE];
const unsigned char *data;
unsigned char *buf;
unsigned long fragoff, fraglen, msglen;
unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen;
BIO *rbio, *wbio;
BUF_MEM *bufm;
BIO_ADDR *tmpclient = NULL;
PACKET pkt, msgpkt, msgpayload, session, cookiepkt;
/* Ensure there is no state left over from a previous invocation */
if (!SSL_clear(s))
return -1;
ERR_clear_error();
rbio = SSL_get_rbio(s);
wbio = SSL_get_wbio(s);
if (!rbio || !wbio) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BIO_NOT_SET);
return -1;
}
/*
* We only peek at incoming ClientHello's until we're sure we are going to
* to respond with a HelloVerifyRequest. If its a ClientHello with a valid
* cookie then we leave it in the BIO for accept to handle.
*/
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL);
/*
* Note: This check deliberately excludes DTLS1_BAD_VER because that version
* requires the MAC to be calculated *including* the first ClientHello
* (without the cookie). Since DTLSv1_listen is stateless that cannot be
* supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via
* SSL_accept)
*/
if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNSUPPORTED_SSL_VERSION);
return -1;
}
if (s->init_buf == NULL) {
if ((bufm = BUF_MEM_new()) == NULL) {
SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
return -1;
}
if (!BUF_MEM_grow(bufm, SSL3_RT_MAX_PLAIN_LENGTH)) {
BUF_MEM_free(bufm);
SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
return -1;
}
s->init_buf = bufm;
}
buf = (unsigned char *)s->init_buf->data;
do {
/* Get a packet */
clear_sys_error();
/*
* Technically a ClientHello could be SSL3_RT_MAX_PLAIN_LENGTH
* + DTLS1_RT_HEADER_LENGTH bytes long. Normally init_buf does not store
* the record header as well, but we do here. We've set up init_buf to
* be the standard size for simplicity. In practice we shouldn't ever
* receive a ClientHello as long as this. If we do it will get dropped
* in the record length check below.
*/
n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
if (n <= 0) {
if (BIO_should_retry(rbio)) {
/* Non-blocking IO */
goto end;
}
return -1;
}
/* If we hit any problems we need to clear this packet from the BIO */
clearpkt = 1;
if (!PACKET_buf_init(&pkt, buf, n)) {
SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
return -1;
}
/*
* Parse the received record. If there are any problems with it we just
* dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is
* resilient in the face of invalid records (e.g., invalid formatting,
* length, MAC, etc.). In general, invalid records SHOULD be silently
* discarded, thus preserving the association; however, an error MAY be
* logged for diagnostic purposes."
*/
/* this packet contained a partial record, dump it */
if (n < DTLS1_RT_HEADER_LENGTH) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_RECORD_TOO_SMALL);
goto end;
}
if (s->msg_callback)
s->msg_callback(0, 0, SSL3_RT_HEADER, buf,
DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
/* Get the record header */
if (!PACKET_get_1(&pkt, &rectype)
|| !PACKET_get_1(&pkt, &versmajor)) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
goto end;
}
if (rectype != SSL3_RT_HANDSHAKE) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
goto end;
}
/*
* Check record version number. We only check that the major version is
* the same.
*/
if (versmajor != DTLS1_VERSION_MAJOR) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
goto end;
}
if (!PACKET_forward(&pkt, 1)
/* Save the sequence number: 64 bits, with top 2 bytes = epoch */
|| !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE)
|| !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
goto end;
}
/*
* We allow data remaining at the end of the packet because there could
* be a second record (but we ignore it)
*/
/* This is an initial ClientHello so the epoch has to be 0 */
if (seq[0] != 0 || seq[1] != 0) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
goto end;
}
/* Get a pointer to the raw message for the later callback */
data = PACKET_data(&msgpkt);
/* Finished processing the record header, now process the message */
if (!PACKET_get_1(&msgpkt, &msgtype)
|| !PACKET_get_net_3(&msgpkt, &msglen)
|| !PACKET_get_net_2(&msgpkt, &msgseq)
|| !PACKET_get_net_3(&msgpkt, &fragoff)
|| !PACKET_get_net_3(&msgpkt, &fraglen)
|| !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen)
|| PACKET_remaining(&msgpkt) != 0) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
goto end;
}
if (msgtype != SSL3_MT_CLIENT_HELLO) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
goto end;
}
/* Message sequence number can only be 0 or 1 */
if (msgseq > 2) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_INVALID_SEQUENCE_NUMBER);
goto end;
}
/*
* We don't support fragment reassembly for ClientHellos whilst
* listening because that would require server side state (which is
* against the whole point of the ClientHello/HelloVerifyRequest
* mechanism). Instead we only look at the first ClientHello fragment
* and require that the cookie must be contained within it.
*/
if (fragoff != 0 || fraglen > msglen) {
/* Non initial ClientHello fragment (or bad fragment) */
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO);
goto end;
}
if (s->msg_callback)
s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
fraglen + DTLS1_HM_HEADER_LENGTH, s,
s->msg_callback_arg);
if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
goto end;
}
/*
* Verify client version is supported
*/
if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) &&
s->method->version != DTLS_ANY_VERSION) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER);
goto end;
}
if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
|| !PACKET_get_length_prefixed_1(&msgpayload, &session)
|| !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
/*
* Could be malformed or the cookie does not fit within the initial
* ClientHello fragment. Either way we can't handle it.
*/
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
goto end;
}
/*
* Check if we have a cookie or not. If not we need to send a
* HelloVerifyRequest.
*/
if (PACKET_remaining(&cookiepkt) == 0) {
next = LISTEN_SEND_VERIFY_REQUEST;
} else {
/*
* We have a cookie, so lets check it.
*/
if (s->ctx->app_verify_cookie_cb == NULL) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
/* This is fatal */
return -1;
}
if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt),
PACKET_remaining(&cookiepkt)) ==
0) {
/*
* We treat invalid cookies in the same was as no cookie as
* per RFC6347
*/
next = LISTEN_SEND_VERIFY_REQUEST;
} else {
/* Cookie verification succeeded */
next = LISTEN_SUCCESS;
}
}
if (next == LISTEN_SEND_VERIFY_REQUEST) {
WPACKET wpkt;
unsigned int version;
size_t wreclen;
/*
* There was no cookie in the ClientHello so we need to send a
* HelloVerifyRequest. If this fails we do not worry about trying
* to resend, we just drop it.
*/
/*
* Dump the read packet, we don't need it any more. Ignore return
* value
*/
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL);
BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL);
/* Generate the cookie */
if (s->ctx->app_gen_cookie_cb == NULL ||
s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 ||
cookielen > 255) {
SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
/* This is fatal */
return -1;
}
/*
* Special case: for hello verify request, client version 1.0 and we
* haven't decided which version to use yet send back using version
* 1.0 header: otherwise some clients will ignore it.
*/
version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION
: s->version;
/* Construct the record and message headers */
if (!WPACKET_init(&wpkt, s->init_buf)
|| !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE)
|| !WPACKET_put_bytes_u16(&wpkt, version)
/*
* Record sequence number is always the same as in the
* received ClientHello
*/
|| !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE)
/* End of record, start sub packet for message */
|| !WPACKET_start_sub_packet_u16(&wpkt)
/* Message type */
|| !WPACKET_put_bytes_u8(&wpkt,
DTLS1_MT_HELLO_VERIFY_REQUEST)
/*
* Message length - doesn't follow normal TLS convention:
* the length isn't the last thing in the message header.
* We'll need to fill this in later when we know the
* length. Set it to zero for now
*/
|| !WPACKET_put_bytes_u24(&wpkt, 0)
/*
* Message sequence number is always 0 for a
* HelloVerifyRequest
*/
|| !WPACKET_put_bytes_u16(&wpkt, 0)
/*
* We never fragment a HelloVerifyRequest, so fragment
* offset is 0
*/
|| !WPACKET_put_bytes_u24(&wpkt, 0)
/*
* Fragment length is the same as message length, but
* this *is* the last thing in the message header so we
* can just start a sub-packet. No need to come back
* later for this one.
*/
|| !WPACKET_start_sub_packet_u24(&wpkt)
/* Create the actual HelloVerifyRequest body */
|| !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen)
/* Close message body */
|| !WPACKET_close(&wpkt)
/* Close record body */
|| !WPACKET_close(&wpkt)
|| !WPACKET_get_total_written(&wpkt, &wreclen)
|| !WPACKET_finish(&wpkt)) {
SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
WPACKET_cleanup(&wpkt);
/* This is fatal */
return -1;
}
/*
* Fix up the message len in the message header. Its the same as the
* fragment len which has been filled in by WPACKET, so just copy
* that. Destination for the message len is after the record header
* plus one byte for the message content type. The source is the
* last 3 bytes of the message header
*/
memcpy(&buf[DTLS1_RT_HEADER_LENGTH + 1],
&buf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3],
3);
if (s->msg_callback)
s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
if ((tmpclient = BIO_ADDR_new()) == NULL) {
SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
goto end;
}
/*
* This is unnecessary if rbio and wbio are one and the same - but
* maybe they're not. We ignore errors here - some BIOs do not
* support this.
*/
if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
(void)BIO_dgram_set_peer(wbio, tmpclient);
}
BIO_ADDR_free(tmpclient);
tmpclient = NULL;
if (BIO_write(wbio, buf, wreclen) < (int)wreclen) {
if (BIO_should_retry(wbio)) {
/*
* Non-blocking IO...but we're stateless, so we're just
* going to drop this packet.
*/
goto end;
}
return -1;
}
if (BIO_flush(wbio) <= 0) {
if (BIO_should_retry(wbio)) {
/*
* Non-blocking IO...but we're stateless, so we're just
* going to drop this packet.
*/
goto end;
}
return -1;
}
}
} while (next != LISTEN_SUCCESS);
/*
* Set expected sequence numbers to continue the handshake.
*/
s->d1->handshake_read_seq = 1;
s->d1->handshake_write_seq = 1;
s->d1->next_handshake_write_seq = 1;
DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq);
/*
* We are doing cookie exchange, so make sure we set that option in the
* SSL object
*/
SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
/*
* Tell the state machine that we've done the initial hello verify
* exchange
*/
ossl_statem_set_hello_verify_done(s);
/*
* Some BIOs may not support this. If we fail we clear the client address
*/
if (BIO_dgram_get_peer(rbio, client) <= 0)
BIO_ADDR_clear(client);
ret = 1;
clearpkt = 0;
end:
BIO_ADDR_free(tmpclient);
BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL);
if (clearpkt) {
/* Dump this packet. Ignore return value */
BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
}
return ret;
}
#endif
static int dtls1_handshake_write(SSL *s)
{
return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
}
#ifndef OPENSSL_NO_HEARTBEATS
# define HEARTBEAT_SIZE(payload, padding) ( \
1 /* heartbeat type */ + \
2 /* heartbeat length */ + \
(payload) + (padding))
# define HEARTBEAT_SIZE_STD(payload) HEARTBEAT_SIZE(payload, 16)
int dtls1_process_heartbeat(SSL *s, unsigned char *p, unsigned int length)
{
unsigned char *pl;
unsigned short hbtype;
unsigned int payload;
unsigned int padding = 16; /* Use minimum padding */
if (s->msg_callback)
s->msg_callback(0, s->version, DTLS1_RT_HEARTBEAT,
p, length, s, s->msg_callback_arg);
/* Read type and payload length */
if (HEARTBEAT_SIZE_STD(0) > length)
return 0; /* silently discard */
if (length > SSL3_RT_MAX_PLAIN_LENGTH)
return 0; /* silently discard per RFC 6520 sec. 4 */
hbtype = *p++;
n2s(p, payload);
if (HEARTBEAT_SIZE_STD(payload) > length)
return 0; /* silently discard per RFC 6520 sec. 4 */
pl = p;
if (hbtype == TLS1_HB_REQUEST) {
unsigned char *buffer, *bp;
unsigned int write_length = HEARTBEAT_SIZE(payload, padding);
int r;
if (write_length > SSL3_RT_MAX_PLAIN_LENGTH)
return 0;
/* Allocate memory for the response. */
buffer = OPENSSL_malloc(write_length);
if (buffer == NULL)
return -1;
bp = buffer;
/* Enter response type, length and copy payload */
*bp++ = TLS1_HB_RESPONSE;
s2n(payload, bp);
memcpy(bp, pl, payload);
bp += payload;
/* Random padding */
if (RAND_bytes(bp, padding) <= 0) {
OPENSSL_free(buffer);
return -1;
}
r = dtls1_write_bytes(s, DTLS1_RT_HEARTBEAT, buffer, write_length);
if (r >= 0 && s->msg_callback)
s->msg_callback(1, s->version, DTLS1_RT_HEARTBEAT,
buffer, write_length, s, s->msg_callback_arg);
OPENSSL_free(buffer);
if (r < 0)
return r;
} else if (hbtype == TLS1_HB_RESPONSE) {
unsigned int seq;
/*
* We only send sequence numbers (2 bytes unsigned int), and 16
* random bytes, so we just try to read the sequence number
*/
n2s(pl, seq);
if (payload == 18 && seq == s->tlsext_hb_seq) {
dtls1_stop_timer(s);
s->tlsext_hb_seq++;
s->tlsext_hb_pending = 0;
}
}
return 0;
}
int dtls1_heartbeat(SSL *s)
{
unsigned char *buf, *p;
int ret = -1;
unsigned int payload = 18; /* Sequence number + random bytes */
unsigned int padding = 16; /* Use minimum padding */
unsigned int size;
/* Only send if peer supports and accepts HB requests... */
if (!(s->tlsext_heartbeat & SSL_DTLSEXT_HB_ENABLED) ||
s->tlsext_heartbeat & SSL_DTLSEXT_HB_DONT_SEND_REQUESTS) {
SSLerr(SSL_F_DTLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
return -1;
}
/* ...and there is none in flight yet... */
if (s->tlsext_hb_pending) {
SSLerr(SSL_F_DTLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PENDING);
return -1;
}
/* ...and no handshake in progress. */
if (SSL_in_init(s) || ossl_statem_get_in_handshake(s)) {
SSLerr(SSL_F_DTLS1_HEARTBEAT, SSL_R_UNEXPECTED_MESSAGE);
return -1;
}
/*-
* Create HeartBeat message, we just use a sequence number
* as payload to distinguish different messages and add
* some random stuff.
*/
size = HEARTBEAT_SIZE(payload, padding);
buf = OPENSSL_malloc(size);
if (buf == NULL) {
SSLerr(SSL_F_DTLS1_HEARTBEAT, ERR_R_MALLOC_FAILURE);
return -1;
}
p = buf;
/* Message Type */
*p++ = TLS1_HB_REQUEST;
/* Payload length (18 bytes here) */
s2n(payload, p);
/* Sequence number */
s2n(s->tlsext_hb_seq, p);
/* 16 random bytes */
if (RAND_bytes(p, 16) <= 0) {
SSLerr(SSL_F_DTLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
goto err;
}
p += 16;
/* Random padding */
if (RAND_bytes(p, padding) <= 0) {
SSLerr(SSL_F_DTLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
goto err;
}
ret = dtls1_write_bytes(s, DTLS1_RT_HEARTBEAT, buf, size);
if (ret >= 0) {
if (s->msg_callback)
s->msg_callback(1, s->version, DTLS1_RT_HEARTBEAT,
buf, size, s, s->msg_callback_arg);
dtls1_start_timer(s);
s->tlsext_hb_pending = 1;
}
err:
OPENSSL_free(buf);
return ret;
}
#endif
int dtls1_shutdown(SSL *s)
{
int ret;
#ifndef OPENSSL_NO_SCTP
BIO *wbio;
wbio = SSL_get_wbio(s);
if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
!(s->shutdown & SSL_SENT_SHUTDOWN)) {
ret = BIO_dgram_sctp_wait_for_dry(wbio);
if (ret < 0)
return -1;
if (ret == 0)
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
NULL);
}
#endif
ret = ssl3_shutdown(s);
#ifndef OPENSSL_NO_SCTP
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
#endif
return ret;
}
int dtls1_query_mtu(SSL *s)
{
if (s->d1->link_mtu) {
s->d1->mtu =
s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
s->d1->link_mtu = 0;
}
/* AHA! Figure out the MTU, and stick to the right size */
if (s->d1->mtu < dtls1_min_mtu(s)) {
if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
s->d1->mtu =
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
/*
* I've seen the kernel return bogus numbers when it doesn't know
* (initial write), so just make sure we have a reasonable number
*/
if (s->d1->mtu < dtls1_min_mtu(s)) {
/* Set to min mtu */
s->d1->mtu = dtls1_min_mtu(s);
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
s->d1->mtu, NULL);
}
} else
return 0;
}
return 1;
}
static unsigned int dtls1_link_min_mtu(void)
{
return (g_probable_mtu[(sizeof(g_probable_mtu) /
sizeof(g_probable_mtu[0])) - 1]);
}
unsigned int dtls1_min_mtu(SSL *s)
{
return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
}
size_t DTLS_get_data_mtu(const SSL *s)
{
size_t mac_overhead, int_overhead, blocksize, ext_overhead;
const SSL_CIPHER *ciph = SSL_get_current_cipher(s);
size_t mtu = s->d1->mtu;
if (ciph == NULL)
return 0;
if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead,
&blocksize, &ext_overhead))
return 0;
if (SSL_USE_ETM(s))
ext_overhead += mac_overhead;
else
int_overhead += mac_overhead;
/* Subtract external overhead (e.g. IV/nonce, separate MAC) */
if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu)
return 0;
mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH;
/* Round encrypted payload down to cipher block size (for CBC etc.)
* No check for overflow since 'mtu % blocksize' cannot exceed mtu. */
if (blocksize)
mtu -= (mtu % blocksize);
/* Subtract internal overhead (e.g. CBC padding len byte) */
if (int_overhead >= mtu)
return 0;
mtu -= int_overhead;
return mtu;
}
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