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Fix crash as server when resuming with SNI.

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Thanks to Denis Denisov for noting that |host_name| could be used while
uninitialised in the resumption case.

While in the area, this change also renames |servername_done| to
something more reasonable and removes a documented value that was never
used. Additionally, the SNI ack was only sent when not resuming so
calculating whether it should be sent when processing ClientHello
extensions (which is after s->hit has been set) is superfluous.

Lastly, since SNI is only acked by servers, there's no need to worry
about the SNI callback returning NOACK in the client case.

Change-Id: Ie4ecfc347bd7afaf93b12526ff9311cc45da4df6
Reviewed-on: https://boringssl-review.googlesource.com/1700
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
Adam Langley 2014-09-02 13:52:56 -07:00 committed by Adam Langley
parent 04dbb7f1d1
commit ed8270a55c
2 changed files with 47 additions and 45 deletions
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9
include/openssl/ssl.h
View File

@ -1375,12 +1375,9 @@ struct ssl_st
void *arg);
void *tlsext_debug_arg;
char *tlsext_hostname;
int servername_done; /* no further mod of servername
0 : call the servername extension callback.
1 : prepare 2, allow last ack just after in server callback.
2 : don't call servername callback, no ack in server hello
*/
/* should_ack_sni is true if the SNI extension should be acked. This is
* only used by a server. */
char should_ack_sni;
/* RFC4507 session ticket expected to be received or sent */
int tlsext_ticket_expected;
size_t tlsext_ecpointformatlist_length;

83
ssl/t1_lib.c
View File

@ -1212,7 +1212,7 @@ unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf, unsigned c
ret+=2;
if (ret>=limit) return NULL; /* this really never occurs, but ... */
if (!s->hit && s->servername_done == 1 && s->session->tlsext_hostname != NULL)
if (!s->hit && s->should_ack_sni && s->session->tlsext_hostname != NULL)
{
if ((long)(limit - ret - 4) < 0) return NULL;
@ -1418,7 +1418,7 @@ static int ssl_scan_clienthello_tlsext(SSL *s, CBS *cbs, int *out_alert)
CBS extensions;
size_t i;
s->servername_done = 0;
s->should_ack_sni = 0;
s->s3->next_proto_neg_seen = 0;
s->s3->tmp.certificate_status_expected = 0;
@ -1506,6 +1506,7 @@ static int ssl_scan_clienthello_tlsext(SSL *s, CBS *cbs, int *out_alert)
if (type == TLSEXT_TYPE_server_name)
{
CBS server_name_list;
char have_seen_host_name = 0;
if (!CBS_get_u16_length_prefixed(&extension, &server_name_list) ||
CBS_len(&server_name_list) < 1 ||
@ -1532,45 +1533,49 @@ static int ssl_scan_clienthello_tlsext(SSL *s, CBS *cbs, int *out_alert)
if (name_type != TLSEXT_NAMETYPE_host_name)
continue;
if (have_seen_host_name)
{
/* The ServerNameList MUST NOT contain
* more than one name of the same
* name_type. */
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
have_seen_host_name = 1;
if (!CBS_get_u16_length_prefixed(&server_name_list, &host_name) ||
CBS_len(&host_name) < 1)
{
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
if (CBS_len(&host_name) > TLSEXT_MAXLEN_host_name ||
CBS_contains_zero_byte(&host_name))
{
*out_alert = SSL_AD_UNRECOGNIZED_NAME;
return 0;
}
if (!s->hit)
{
assert(s->session->tlsext_hostname == NULL);
if (s->session->tlsext_hostname)
{
/* The ServerNameList MUST NOT
contain more than one name of
the same name_type. */
/* This should be impossible. */
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
if (!CBS_get_u16_length_prefixed(&server_name_list, &host_name) ||
CBS_len(&host_name) < 1)
{
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
if (CBS_len(&host_name) > TLSEXT_MAXLEN_host_name ||
CBS_contains_zero_byte(&host_name))
{
*out_alert = SSL_AD_UNRECOGNIZED_NAME;
return 0;
}
/* Copy the hostname as a string. */
if (!CBS_strdup(&host_name, &s->session->tlsext_hostname))
{
*out_alert = SSL_AD_INTERNAL_ERROR;
return 0;
}
s->servername_done = 1;
}
else
{
s->servername_done = s->session->tlsext_hostname
&& strlen(s->session->tlsext_hostname) == CBS_len(&host_name)
&& strncmp(s->session->tlsext_hostname,
(char *)CBS_data(&host_name), CBS_len(&host_name)) == 0;
s->should_ack_sni = 1;
}
}
}
@ -2147,12 +2152,14 @@ static int ssl_check_clienthello_tlsext(SSL *s)
case SSL_TLSEXT_ERR_ALERT_WARNING:
ssl3_send_alert(s,SSL3_AL_WARNING,al);
return 1;
return 1;
case SSL_TLSEXT_ERR_NOACK:
s->servername_done=0;
default:
return 1;
s->should_ack_sni = 0;
return 1;
default:
return 1;
}
}
@ -2200,17 +2207,15 @@ static int ssl_check_serverhello_tlsext(SSL *s)
switch (ret)
{
case SSL_TLSEXT_ERR_ALERT_FATAL:
ssl3_send_alert(s,SSL3_AL_FATAL,al);
ssl3_send_alert(s,SSL3_AL_FATAL,al);
return -1;
case SSL_TLSEXT_ERR_ALERT_WARNING:
ssl3_send_alert(s,SSL3_AL_WARNING,al);
return 1;
case SSL_TLSEXT_ERR_NOACK:
s->servername_done=0;
default:
return 1;
return 1;
default:
return 1;
}
}