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
Adaption to 2.3: reserve +8 bytes in frame->extra_buffer - if compression
is not enabled, the 2.3 code does not reserve space for compression
overhead (2.4 code does), so the buffer ends up being too small.
+3 is not sufficient because the buffer handling code also does some
alignment tricks...
This reverts commit 4ec70ca227370380011d072c09b739135e236183.
Signed-off-by: Gert Doering <g...@greenie.muc.de>
Message-Id: <1423390725-13438-1-git-send-email-g...@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9450
(cherry picked from commit 9e0963c11aa439deb382d7d6bc40b6ade999401c)
---
src/openvpn/init.c | 24 ++++++++++++++++++++++++
src/openvpn/mtu.h | 6 ++++++
src/openvpn/ssl.c | 10 ++++++----
3 files changed, 36 insertions(+), 4 deletions(-)
diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index 4cfa132..48b28fc 100644
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -1798,6 +1798,19 @@ 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
}
@@ -2400,6 +2413,17 @@ do_init_frame (struct context *c)
*/
frame_finalize_options (c, NULL);
+ /* 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
+ * send path in f->extra_buffer (+leave room for alignment)
+ *
+ * f->extra_frame is adjusted when peer-id option is push-received
+ */
+ frame_add_to_extra_link(&c->c2.frame, 3);
+ frame_add_to_extra_buffer(&c->c2.frame, 8);
+
#ifdef ENABLE_FRAGMENT
/*
* Set frame parameter for fragment code. This is necessary because
diff --git a/src/openvpn/mtu.h b/src/openvpn/mtu.h
index 29ec21f..bccd681 100644
--- a/src/openvpn/mtu.h
+++ b/src/openvpn/mtu.h
@@ -258,6 +258,12 @@ frame_headroom (const struct frame *f, const unsigned int
flag_mask)
*/
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)
{
frame->extra_frame += increment;
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index b62dc12..423aedb 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -267,14 +267,16 @@ 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 */
}
/*
--
2.1.3
