Hi Łukasz,
On Thursday 29 of January 2015 21:50:48 Lukasz Rymanowski wrote:
> Initial setting of MTU should be IMTU. This is actually our assumption
> in other part of code, that IMTU is something we start with and change
> if needed after exchange MTU procedure.
>
> If we are not able to get IMTU from the socket just disconnect, there is
> something wrong going on.
>
> Without this patch you can face the issue with following scenario:
> 1. On connection complete MTU is set to 23
> 2. BfA sends Exchange MTU Request with MTU set to IMTU
> 3. Remote device response with MTU equal to what BfA sends
> 4. In that case, since remote MTU is equal to ours, there is no
> update in bt_att, so bt_att keep using MTU = 23
> 5. Remote sends packets highier then 23 and bt_att start to drop not
> complete packets.
>
> Issue found and fix tested on UPF50
> ---
> v2: Use local GError instead the one provided as a function parameter
>
> android/gatt.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/android/gatt.c b/android/gatt.c
> index 466c1ea..23ffb9e 100644
> --- a/android/gatt.c
> +++ b/android/gatt.c
> @@ -1488,6 +1488,7 @@ static void connect_cb(GIOChannel *io, GError *gerr, gpointer user_data)
> struct connect_data data;
> struct att_range range;
> uint32_t status;
> + GError *err = NULL;
> GAttrib *attrib;
> uint16_t mtu;
> uint16_t cid;
> @@ -1510,9 +1511,14 @@ static void connect_cb(GIOChannel *io, GError *gerr, gpointer user_data)
> goto reply;
> }
>
> - if (!bt_io_get(io, &gerr, BT_IO_OPT_IMTU, &mtu, BT_IO_OPT_CID, &cid,
> - BT_IO_OPT_INVALID) || cid == ATT_CID)
> - mtu = ATT_DEFAULT_LE_MTU;
> + if (!bt_io_get(io, &err, BT_IO_OPT_IMTU, &mtu, BT_IO_OPT_CID, &cid,
> + BT_IO_OPT_INVALID)) {
> + error("gatt: Could not get imtu: %s", err->message);
> + device_set_state(dev, DEVICE_DISCONNECTED);
> + status = GATT_FAILURE;
> + g_error_free(err);
> + goto reply;
> + }
>
> attrib = g_attrib_new(io, mtu);
> if (!attrib) {
>
Both patches applied, thanks.
--
Best regards,
Szymon Janc
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