Re: [Qemu-devel] [PATCH] io: ignore case when matching websockets HTTP headers

[Denis V. Lunev]

On 02/28/2017 01:09 PM, Daniel P. Berrange wrote:
> On Mon, Feb 27, 2017 at 03:20:37PM -0600, Eric Blake wrote:
>> On 02/27/2017 02:14 PM, Daniel P. Berrange wrote:
>>> According to RFC7230 Section 3.2, header field name is case-insensitive.
>>> Convert the header data into all lowercase before doing string matching
>>> on the headers.
>>>
>>> Signed-off-by: Daniel P. Berrange <address@hidden>
>>> ---
>>>  io/channel-websock.c | 14 +++++++++-----
>>>  1 file changed, 9 insertions(+), 5 deletions(-)
>>>
>>> @@ -223,7 +223,7 @@ static int 
>>> qio_channel_websock_handshake_process(QIOChannelWebsock *ioc,
>>>  static int qio_channel_websock_handshake_read(QIOChannelWebsock *ioc,
>>>                                                Error **errp)
>>>  {
>>> -    char *handshake_end;
>>> +    char *handshake_end, *tmp;
>>>      ssize_t ret;
>>>      /* Typical HTTP headers from novnc are 512 bytes, so limiting
>>>       * total header size to 4096 is easily enough. */
>> Drive-by grammar nit: s/easily/easy/
>>
>>> @@ -249,9 +249,13 @@ static int 
>>> qio_channel_websock_handshake_read(QIOChannelWebsock *ioc,
>>>          }
>>>      }
>>>  
>>> +    for (tmp = (char *)ioc->encinput.buffer; tmp < handshake_end; tmp++) {
>>> +        *tmp = g_ascii_tolower(*tmp);
>>> +    }
>>> +
>>>      if (qio_channel_websock_handshake_process(ioc,
>>>                                                (char *)ioc->encinput.buffer,
>>> -                                              ioc->encinput.offset,
>>> +                                              handshake_end - (char 
>>> *)ioc->encinput.buffer,
>> I'm not sure why this change is here; nothing else in the patch changed
>> ioc->encinput.offset.
> It is a related bug. The ioc->encinput buffer contains upto 4096
> bytes, but that data may cover both the header & payload. The
> handshake_end pointer refers to the end of the header region.
> So if we just pass encinput.offset, then handshake_process()
> will be searching part of the payload as well as the header.
> This might cause it do match the wrong data. I guess I should
> have made that clear in the commit, or even tput it in a
> separate commit
>
> Regards,
> Daniel
with this comment this is obviously correct :)

Reviewed-by: Denis V. Lunev <address@hidden>