[OpenWrt-Devel] [PATCH 2/3] Fix SSL negotiation being interrupted by .notify_write from BIO method.

[Yousong Zhou]

On 12 December 2014 at 19:36, Felix Fietkau <nbd at openwrt.org> wrote:
> On 2014-12-12 05:16, Yousong Zhou wrote:
>> On 12 December 2014 at 00:42, Felix Fietkau <nbd at openwrt.org> wrote:
>>> On 2014-11-11 11:34, Yousong Zhou wrote:
>>>> ustream_ssl_check_conn() may be called by .notify_write while a previous
>>>> SSL_connect() is still in process.  This can happen because the
>>>> .notify_write callback will may be triggered by writes in the BIO
>>>> methods.
>>>>
>>>> Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
>>>> ---
>>>>  ustream-ssl.c |   19 +++++++++++++++----
>>>>  ustream-ssl.h |    1 +
>>>>  2 files changed, 16 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/ustream-ssl.c b/ustream-ssl.c
>>>> index dd0faf9..84104b0 100644
>>>> --- a/ustream-ssl.c
>>>> +++ b/ustream-ssl.c
>>>> @@ -34,12 +34,22 @@ static void ustream_ssl_error_cb(struct uloop_timeout *t)
>>>>               us->notify_error(us, error, __ustream_ssl_strerror(us->error, buffer, sizeof(buffer)));
>>>>  }
>>>>
>>>> +static enum ssl_conn_status ustream_ssl_do_connect(struct ustream_ssl *us)
>>>> +{
>>>> +     enum ssl_conn_status status;
>>>> +
>>>> +     us->connecting = true;
>>>> +     status = __ustream_ssl_connect(us);
>>>> +     us->connecting = false;
>>>> +     return status;
>>>> +}
>>>> +
>>> I think this can be fixed in a much simpler way. Simply prevent
>>> re-entrant calls to __ustream_ssl_connect through a static variable.
>>
>> Guarding it with a single static variable do not work well with
>> multiple instances of ustream_ssl.
> How so? Even with multiple instances a call stack from one instance that
> calls do_connect should not end up with re-entrant calls for a different
> instance.

But we do not want do_connect() of different instances intervening
with each other, do we?


                yousong
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