generic-library/openssl
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Remove instances in libssl of the constant 28 (for size of IPv4 header + UDP)

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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 59669b6abf620d1ed2ef4d1e2df25c998b89b64d)

Conflicts:
	ssl/d1_both.c
This commit is contained in:
Matt Caswell 2014-12-01 23:58:05 +00:00
parent ccecdb130c
commit 05e769f269
6 changed files with 74 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
ssl/d1_both.c
View File

@ -156,9 +156,9 @@ static unsigned char bitmask_start_values[] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe
static unsigned char bitmask_end_values[] = {0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f};
/* XDTLS: figure out the right values */
static unsigned int g_probable_mtu[] = {1500 - 28, 512 - 28, 256 - 28};
static const unsigned int g_probable_mtu[] = {1500, 512, 256};
static unsigned int dtls1_guess_mtu(unsigned int curr_mtu);
static void dtls1_guess_mtu(SSL *s);
static void dtls1_fix_message_header(SSL *s, unsigned long frag_off,
unsigned long frag_len);
static unsigned char *dtls1_write_message_header(SSL *s,
@ -226,18 +226,24 @@ void dtls1_hm_fragment_free(hm_fragment *frag)
static void 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() && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
if (s->d1->mtu < dtls1_min_mtu(s) && !(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())
if (s->d1->mtu < dtls1_min_mtu(s))
{
s->d1->mtu = 0;
s->d1->mtu = dtls1_guess_mtu(s->d1->mtu);
dtls1_guess_mtu(s);
BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
s->d1->mtu, NULL);
}
@ -275,7 +281,7 @@ int dtls1_do_write(SSL *s, int type)
}
#endif
OPENSSL_assert(s->d1->mtu >= dtls1_min_mtu()); /* should have something reasonable now */
OPENSSL_assert(s->d1->mtu >= dtls1_min_mtu(s)); /* should have something reasonable now */
if ( s->init_off == 0 && type == SSL3_RT_HANDSHAKE)
OPENSSL_assert(s->init_num ==
@ -1299,26 +1305,40 @@ dtls1_write_message_header(SSL *s, unsigned char *p)
return p;
}
unsigned int
dtls1_min_mtu(void)
unsigned int
dtls1_link_min_mtu(void)
{
return (g_probable_mtu[(sizeof(g_probable_mtu) /
sizeof(g_probable_mtu[0])) - 1]);
}
static unsigned int
dtls1_guess_mtu(unsigned int curr_mtu)
unsigned int
dtls1_min_mtu(SSL *s)
{
return dtls1_link_min_mtu()-BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
}
static void
dtls1_guess_mtu(SSL *s)
{
unsigned int curr_mtu;
unsigned int i;
unsigned int mtu_ovr;
curr_mtu = s->d1->mtu;
mtu_ovr = BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
if ( curr_mtu == 0 )
return g_probable_mtu[0] ;
for ( i = 0; i < sizeof(g_probable_mtu)/sizeof(g_probable_mtu[0]); i++)
if ( curr_mtu > g_probable_mtu[i])
return g_probable_mtu[i];
return curr_mtu;
{
curr_mtu = g_probable_mtu[0] - mtu_ovr;
}
else
{
for ( i = 0; i < sizeof(g_probable_mtu)/sizeof(g_probable_mtu[0]); i++)
if ( curr_mtu > g_probable_mtu[i] - mtu_ovr)
return g_probable_mtu[i] - mtu_ovr;
}
s->d1->mtu = curr_mtu;
}
void

25
ssl/d1_lib.c
View File

@ -139,6 +139,9 @@ 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)
{
@ -234,6 +237,7 @@ void dtls1_clear(SSL *s)
pqueue sent_messages;
pqueue buffered_app_data;
unsigned int mtu;
unsigned int link_mtu;
if (s->d1)
{
@ -243,6 +247,7 @@ 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);
@ -256,6 +261,7 @@ 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;
@ -312,6 +318,25 @@ long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
}
return 0; /* Unexpected state; fail closed. */
/* 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;

4
ssl/dtls1.h
View File

@ -121,6 +121,9 @@ extern "C" {
#define DTLS1_SCTP_AUTH_LABEL "EXPORTER_DTLS_OVER_SCTP"
#endif
/* Max MTU overhead we know about so far is 40 for IPv6 + 8 for UDP */
#define DTLS1_MAX_MTU_OVERHEAD 48
typedef struct dtls1_bitmap_st
{
unsigned long map; /* track 32 packets on 32-bit systems
@ -235,6 +238,7 @@ typedef struct dtls1_state_st
/* Is set when listening for new connections with dtls1_listen() */
unsigned int listen;
unsigned int link_mtu; /* max on-the-wire DTLS packet size */
unsigned int mtu; /* max DTLS packet size */
struct hm_header_st w_msg_hdr;

6
ssl/ssl.h
View File

@ -787,6 +787,10 @@ struct ssl_session_st
SSL_ctrl((ssl),SSL_CTRL_MODE,0,NULL)
#define SSL_set_mtu(ssl, mtu) \
SSL_ctrl((ssl),SSL_CTRL_SET_MTU,(mtu),NULL)
#define DTLS_set_link_mtu(ssl, mtu) \
SSL_ctrl((ssl),DTLS_CTRL_SET_LINK_MTU,(mtu),NULL)
#define DTLS_get_link_min_mtu(ssl) \
SSL_ctrl((ssl),DTLS_CTRL_GET_LINK_MIN_MTU,0,NULL)
#define SSL_get_secure_renegotiation_support(ssl) \
SSL_ctrl((ssl), SSL_CTRL_GET_RI_SUPPORT, 0, NULL)
@ -1836,6 +1840,8 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION)
#define SSL_CTRL_SET_CURRENT_CERT 117
#define SSL_CTRL_CHECK_PROTO_VERSION 119
#define DTLS_CTRL_SET_LINK_MTU 120
#define DTLS_CTRL_GET_LINK_MIN_MTU 121
#define SSL_CERT_SET_FIRST 1

12
ssl/ssl_lib.c
View File

@ -1128,18 +1128,6 @@ long SSL_ctrl(SSL *s,int cmd,long larg,void *parg)
l=s->max_cert_list;
s->max_cert_list=larg;
return(l);
case SSL_CTRL_SET_MTU:
#ifndef OPENSSL_NO_DTLS1
if (larg < (long)dtls1_min_mtu())
return 0;
#endif
if (SSL_IS_DTLS(s))
{
s->d1->mtu = larg;
return larg;
}
return 0;
case SSL_CTRL_SET_MAX_SEND_FRAGMENT:
if (larg < 512 || larg > SSL3_RT_MAX_PLAIN_LENGTH)
return 0;

3
ssl/ssl_locl.h
View File

@ -1201,7 +1201,8 @@ void dtls1_stop_timer(SSL *s);
int dtls1_is_timer_expired(SSL *s);
void dtls1_double_timeout(SSL *s);
int dtls1_send_newsession_ticket(SSL *s);
unsigned int dtls1_min_mtu(void);
unsigned int dtls1_min_mtu(SSL *s);
unsigned int dtls1_link_min_mtu(void);
void dtls1_hm_fragment_free(hm_fragment *frag);
/* some client-only functions */