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Provide a new WPACKET function for filling in all the lengths

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For the psk extension we need to fill in all the lengths of the message so
far, even though we haven't closed the WPACKET yet. This provides a function
to do that.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2259)
This commit is contained in:
Matt Caswell 2017-01-13 16:59:18 +00:00
parent be62b22b52
commit a2b7e65526
2 changed files with 42 additions and 8 deletions
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41
ssl/packet.c
View File

@ -180,12 +180,13 @@ static int put_value(unsigned char *data, size_t value, size_t len)
/*
* Internal helper function used by WPACKET_close() and WPACKET_finish() to
* close a sub-packet and write out its length if necessary.
* Internal helper function used by WPACKET_close(), WPACKET_finish() and
* WPACKET_fill_lengths() to close a sub-packet and write out its length if
* necessary. If |doclose| is 0 then it goes through the motions of closing
* (i.e. it fills in all the lengths), but doesn't actually close anything.
*/
static int wpacket_intern_close(WPACKET *pkt)
static int wpacket_intern_close(WPACKET *pkt, WPACKET_SUB *sub, int doclose)
{
WPACKET_SUB *sub = pkt->subs;
size_t packlen = pkt->written - sub->pwritten;
if (packlen == 0
@ -194,6 +195,10 @@ static int wpacket_intern_close(WPACKET *pkt)
if (packlen == 0
&& sub->flags & WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH) {
/* We can't handle this case. Return an error */
if (!doclose)
return 0;
/* Deallocate any bytes allocated for the length of the WPACKET */
if ((pkt->curr - sub->lenbytes) == sub->packet_len) {
pkt->written -= sub->lenbytes;
@ -211,8 +216,28 @@ static int wpacket_intern_close(WPACKET *pkt)
sub->lenbytes))
return 0;
pkt->subs = sub->parent;
OPENSSL_free(sub);
if (doclose) {
pkt->subs = sub->parent;
OPENSSL_free(sub);
}
return 1;
}
int WPACKET_fill_lengths(WPACKET *pkt)
{
WPACKET_SUB *sub;
assert(pkt->subs != NULL);
if (pkt->subs == NULL)
return 0;
sub = pkt->subs;
do {
if (!wpacket_intern_close(pkt, sub, 0))
return 0;
sub = sub->parent;
} while (sub != NULL);
return 1;
}
@ -226,7 +251,7 @@ int WPACKET_close(WPACKET *pkt)
if (pkt->subs == NULL || pkt->subs->parent == NULL)
return 0;
return wpacket_intern_close(pkt);
return wpacket_intern_close(pkt, pkt->subs, 1);
}
int WPACKET_finish(WPACKET *pkt)
@ -240,7 +265,7 @@ int WPACKET_finish(WPACKET *pkt)
if (pkt->subs == NULL || pkt->subs->parent != NULL)
return 0;
ret = wpacket_intern_close(pkt);
ret = wpacket_intern_close(pkt, pkt->subs, 1);
if (ret) {
OPENSSL_free(pkt->subs);
pkt->subs = NULL;

9
ssl/packet_locl.h
View File

@ -699,6 +699,15 @@ int WPACKET_close(WPACKET *pkt);
*/
int WPACKET_finish(WPACKET *pkt);
/*
* Iterates through all the sub-packets and writes out their lengths as if they
* were being closed. The lengths will be overwritten with the final lengths
* when the sub-packets are eventually closed (which may be different if more
* data is added to the WPACKET). This function will fail if a sub-packet is of
* 0 length and WPACKET_FLAGS_ABANDON_ON_ZERO_LENGTH is used.
*/
int WPACKET_fill_lengths(WPACKET *pkt);
/*
* Initialise a new sub-packet. Additionally |lenbytes| of data is preallocated
* at the start of the sub-packet to store its length once we know it. Don't