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

[Yousong Zhou]

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.

> The
> other checks for us->connecting should be unnecessary, I think
> !us->connected is enough.

Yes.

                yousong

>
> - Felix
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