Re: [Qemu-devel] [PATCH v3] curl: refuse to open URL from HTTP server without range support

[Stefan Hajnoczi <stefanha@redhat.com>]

On Tue, Jul 02, 2013 at 03:19:21PM +0800, Fam Zheng wrote:
> CURL driver requests partial data from server on guest IO req. For HTTP
> and HTTPS, it uses "Range: ***" in requests, and this will not work if
> server not accepting range. This patch does this check when open.
> 
>  * Removed curl_size_cb, which is not used: On one hand it's registered to
>    libcurl as CURLOPT_WRITEFUNCTION, instead of CURLOPT_HEADERFUNCTION,
>    which will get called with *data*, not *header*. On the other hand the
>    s->len is assigned unconditionally later.
> 
>    In this gone function, the sscanf for "Content-Length: %zd", on
>    (void *)ptr, which is not guaranteed to be zero-terminated, is
>    potentially a security bug. So this patch fixes it as a side-effect. The
>    bug is reported as: https://bugs.launchpad.net/qemu/+bug/1188943
>    (Note the bug is marked "private" so you might not be able to see it)
> 
>  * Introduced curl_header_cb, which is used to parse header and mark the
>    server as accepting range if "Accept-Ranges: bytes" line is seen from
>    response header. If protocol is HTTP or HTTPS, but server response has
>    no not this support, refuse to open this URL.
> 
> Note that python builtin module SimpleHTTPServer is an example of not
> supporting range, if you need to test this driver, get a better server
> or use internet URLs.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> 
> ---
> 
> v3: Fix copy&paste error.
>     Improve error text as suggested by Rich.
> 
> ---
> 
>  block/curl.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan