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New approach to handle peer-id related changes to link-mtu.

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Instead of statically increasing link-mtu by +3, keep the old value for
OCC compatibility with old servers/clients, and only increase link-mtu
if peer-id option is enabled (right now: is pushed by server).

If link-mtu has been set in the config, keep configured value, and log
warning (because the extra overhead has to decrease tun-mtu).

Reserve extra +3 bytes in frame->extra_link.

v2: use frame->extra_link, not frame->extra_buffer (receive path on server)
    introduce frame_add_to_link_mtu() to manipulate frame->link_mtu value
    rework comments to make more clear what is happening

This reverts commit f95010ad24.

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <1423390725-13438-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9450
This commit is contained in:
Gert Doering 2015-02-08 11:18:45 +01:00
parent 5d52337788
commit 9e0963c11a
3 changed files with 36 additions and 4 deletions
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24
src/openvpn/init.c
View file

@ -1794,6 +1794,19 @@ do_deferred_options (struct context *c, const unsigned int found)
msg (D_PUSH, "OPTIONS IMPORT: peer-id set");
c->c2.tls_multi->use_peer_id = true;
c->c2.tls_multi->peer_id = c->options.peer_id;
frame_add_to_extra_frame(&c->c2.frame, +3); /* peer-id overhead */
if ( !c->options.ce.link_mtu_defined )
{
frame_add_to_link_mtu(&c->c2.frame, +3);
msg (D_PUSH, "OPTIONS IMPORT: adjusting link_mtu to %d",
EXPANDED_SIZE(&c->c2.frame));
}
else
{
msg (M_WARN, "OPTIONS IMPORT: WARNING: peer-id set, but link-mtu"
" fixed by config - reducing tun-mtu to %d, expect"
" MTU problems", TUN_MTU_SIZE(&c->c2.frame) );
}
}
#endif
}
@ -2403,6 +2416,17 @@ do_init_frame (struct context *c)
#endif
#endif /* USE_COMP */
/* packets with peer-id (P_DATA_V2) need 3 extra bytes in frame (on client)
* and need link_mtu+3 bytes on socket reception (on server).
*
* accomodate receive path in f->extra_link, which has the side effect of
* also increasing send buffers (BUF_SIZE() macro), which need to be
* allocated big enough before receiving peer-id option from server.
*
* f->extra_frame is adjusted when peer-id option is push-received
*/
frame_add_to_extra_link(&c->c2.frame, 3);
#ifdef ENABLE_FRAGMENT
/*
* Set frame parameter for fragment code. This is necessary because

6
src/openvpn/mtu.h
View file

@ -257,6 +257,12 @@ frame_headroom (const struct frame *f, const unsigned int flag_mask)
* frame member adjustment functions
*/
static inline void
frame_add_to_link_mtu (struct frame *frame, const int increment)
{
frame->link_mtu += increment;
}
static inline void
frame_add_to_extra_frame (struct frame *frame, const int increment)
{

10
src/openvpn/ssl.c
View file

@ -264,14 +264,16 @@ tls_get_cipher_name_pair (const char * cipher_name, size_t len) {
return NULL;
}
/**
* Max number of bytes we will add for data structures common to both data and
* control channel packets (1 byte opcode + 3 bytes peer-id).
/*
* Max number of bytes we will add
* for data structures common to both
* data and control channel packets.
* (opcode only).
*/
void
tls_adjust_frame_parameters(struct frame *frame)
{
frame_add_to_extra_frame (frame, 1 + 3); /* space for opcode + peer-id */
frame_add_to_extra_frame (frame, 1); /* space for opcode */
}
/*