[FFmpeg-devel] [PATCH v3] avformat/url: check url root node when rel include double dot

[Steven Liu]

> 2020年4月27日 下午7:14，Nicolas George <george at nsup.org> 写道：
> 
> Steven Liu (12020-04-27):
>> fix ticket: 8625
>> and add testcase into url for double dot corner case
>> 
>> Signed-off-by: Steven Liu <liuqi05 at kuaishou.com>
>> ---
>> libavformat/tests/url.c |  3 +++
>> libavformat/url.c       | 21 +++++++++++++++++++--
>> tests/ref/fate/url      |  3 +++
>> 3 files changed, 25 insertions(+), 2 deletions(-)
>> 
>> diff --git a/libavformat/tests/url.c b/libavformat/tests/url.c
>> index 5e484fd428..02d0d59aa8 100644
>> --- a/libavformat/tests/url.c
>> +++ b/libavformat/tests/url.c
>> @@ -56,6 +56,7 @@ int main(void)
>>     test("/foo/bar", "baz");
>>     test("/foo/bar", "../baz");
>>     test("/foo/bar", "/baz");
>> +    test("/foo/bar", "../../../baz");
>>     test("http://server/foo/", "baz");
>>     test("http://server/foo/bar", "baz");
>>     test("http://server/foo/", "../baz");
>> @@ -65,6 +66,8 @@ int main(void)
>>     test("http://server/foo/bar?param=value/with/slashes", "/baz");
>>     test("http://server/foo/bar?param&otherparam", "?someparam");
>>     test("http://server/foo/bar", "//other/url");
>> +    test("http://server/foo/bar", "../../../../../other/url");
>> +    test("http://server/foo/bar", "/../../../../../other/url");
>> 
>>     printf("\nTesting av_url_split:\n");
>>     test2("/foo/bar");
>> diff --git a/libavformat/url.c b/libavformat/url.c
>> index 596fb49cfc..0aa50ab9a7 100644
>> --- a/libavformat/url.c
>> +++ b/libavformat/url.c
>> @@ -81,6 +81,7 @@ void ff_make_absolute_url(char *buf, int size, const char *base,
>>                           const char *rel)
>> {
>>     char *sep, *path_query;
>> +    char *root, *p;
>>     /* Absolute path, relative to the current server */
>>     if (base && strstr(base, "://") && rel[0] == '/') {
>>         if (base != buf)
>> @@ -120,16 +121,32 @@ void ff_make_absolute_url(char *buf, int size, const char *base,
>>         return;
>>     }
>> 
>> +    root = p = buf;
>> +    /* Get the path root of the url which start by "://" */
>> +    if (p && strstr(p, "://")) {
>> +        sep = strstr(p, "://");
>> +        if (sep) {
>> +            sep += 3;
>> +            root = strchr(sep, '/');
>> +        }
>> +    }
>> +
>>     /* Remove the file name from the base url */
>>     sep = strrchr(buf, '/');
>> +    if (sep <= root)
>> +        sep = root;
>> +
>>     if (sep)
>>         sep[1] = '\0';
>>     else
>>         buf[0] = '\0';
>>     while (av_strstart(rel, "../", NULL) && sep) {
>>         /* Remove the path delimiter at the end */
>> -        sep[0] = '\0';
>> -        sep = strrchr(buf, '/');
>> +        if (sep > root) {
>> +            sep[0] = '\0';
>> +            sep = strrchr(buf, '/');
>> +        }
>> +
>>         /* If the next directory name to pop off is "..", break here */
>>         if (!strcmp(sep ? &sep[1] : buf, "..")) {
>>             /* Readd the slash we just removed */
>> diff --git a/tests/ref/fate/url b/tests/ref/fate/url
>> index 980b2ce1f9..c8260a97be 100644
>> --- a/tests/ref/fate/url
>> +++ b/tests/ref/fate/url
>> @@ -3,6 +3,7 @@ Testing ff_make_absolute_url:
>>                                           /foo/bar baz                  => /foo/baz
>>                                           /foo/bar ../baz               => /baz
>>                                           /foo/bar /baz                 => /baz
>> +                                          /foo/bar ../../../baz         => /baz
>>                                 http://server/foo/ baz                  => http://server/foo/baz
>>                              http://server/foo/bar baz                  => http://server/foo/baz
>>                                 http://server/foo/ ../baz               => http://server/baz
>> @@ -12,6 +13,8 @@ Testing ff_make_absolute_url:
>>     http://server/foo/bar?param=value/with/slashes /baz                 => http://server/baz
>>             http://server/foo/bar?param&otherparam ?someparam           => http://server/foo/bar?someparam
>>                              http://server/foo/bar //other/url          => http://other/url
>> +                             http://server/foo/bar ../../../../../other/url => http://server/other/url
> 
>> +                             http://server/foo/bar /../../../../../other/url => http://server/../../../../../other/url
> 
> Is this supposed to be the proper result?
/../../../../../other/url,  this is the absolute path, so just concat and don’t process,
Or what do you want to say?
> 
>> 
>> Testing av_url_split:
>> /foo/bar                                                     =>                                                    -1 /foo/bar
> 
> Regards,
> 
> -- 
>  Nicolas George

Thanks

Steven Liu