Remove instances in libssl of the constant 28 (for size of IPv4 header + UDP)

and instead use the value provided by the underlying BIO. Also provide some
new DTLS_CTRLs so that the library user can set the mtu without needing to
know this constant. These new DTLS_CTRLs provide the capability to set the
link level mtu to be used (i.e. including this IP/UDP overhead). The previous
DTLS_CTRLs required the library user to subtract this overhead first.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 59669b6abf)

Conflicts:
	ssl/d1_both.c
	ssl/ssl_lib.c
This commit is contained in:
Matt Caswell
2014-12-01 23:58:05 +00:00
parent 59ee70e386
commit 4c21e004a3
6 changed files with 74 additions and 31 deletions

View File

@@ -113,6 +113,9 @@ int dtls1_new(SSL *s)
d1->cookie_len = sizeof(s->d1->cookie);
}
d1->link_mtu = 0;
d1->mtu = 0;
if( ! d1->unprocessed_rcds.q || ! d1->processed_rcds.q
|| ! d1->buffered_messages || ! d1->sent_messages || ! d1->buffered_app_data.q)
{
@@ -208,6 +211,7 @@ void dtls1_clear(SSL *s)
pqueue sent_messages;
pqueue buffered_app_data;
unsigned int mtu;
unsigned int link_mtu;
if (s->d1)
{
@@ -217,6 +221,7 @@ void dtls1_clear(SSL *s)
sent_messages = s->d1->sent_messages;
buffered_app_data = s->d1->buffered_app_data.q;
mtu = s->d1->mtu;
link_mtu = s->d1->link_mtu;
dtls1_clear_queues(s);
@@ -230,6 +235,7 @@ void dtls1_clear(SSL *s)
if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)
{
s->d1->mtu = mtu;
s->d1->link_mtu = link_mtu;
}
s->d1->unprocessed_rcds.q = unprocessed_rcds;
@@ -275,6 +281,25 @@ long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
* fail closed if the version is not as expected. */
return s->version == DTLS_MAX_VERSION;
/* Just one protocol version is supported so far;
* fail closed if the version is not as expected. */
return s->version == DTLS_MAX_VERSION;
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;