Re: [FFmpeg-devel] [PATCH] Percent-encode URL paths in HLS playlists

["softworkz ." <softworkz-at-hotmail.com@ffmpeg.org>]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of Timothy
> Allen via ffmpeg-devel
> Sent: Freitag, 23. Mai 2025 16:53
> To: ffmpeg-devel@ffmpeg.org
> Cc: Timothy Allen <tim@treehouse.org.za>
> Subject: [FFmpeg-devel] [PATCH] Percent-encode URL paths in HLS playlists
> 
> This commit closes trac ticket 10679.
> 
> Signed-off-by: Timothy Allen <tim@treehouse.org.za>
> ---
>  libavformat/hls.c |  9 +++++++++
>  libavformat/url.c | 35 +++++++++++++++++++++++++++++++++++
>  libavformat/url.h |  9 +++++++++
>  3 files changed, 53 insertions(+)
> 
> diff --git a/libavformat/hls.c b/libavformat/hls.c
> index c7b655c83c..49436d8184 100644
> --- a/libavformat/hls.c
> +++ b/libavformat/hls.c
> @@ -1021,6 +1021,15 @@ static int parse_playlist(HLSContext *c, const char
> *url,
>                      seg->key = NULL;
>                  }
> 
> +                ff_percent_encode_url(tmp_str, sizeof(tmp_str), line);
> +                if (!tmp_str[0]) {
> +                    ret = AVERROR_INVALIDDATA;
> +                    if (seg->key)
> +                        av_free(seg->key);
> +                    av_free(seg);
> +                    goto fail;
> +                }
> +                strcpy(line, av_strdup(tmp_str));
>                  ff_make_absolute_url(tmp_str, sizeof(tmp_str), url, line);
>                  if (!tmp_str[0]) {
>                      ret = AVERROR_INVALIDDATA;
> diff --git a/libavformat/url.c b/libavformat/url.c
> index d5dd6a4666..69d68d4248 100644
> --- a/libavformat/url.c
> +++ b/libavformat/url.c
> @@ -324,6 +324,41 @@ int ff_make_absolute_url(char *buf, int size, const char
> *base,
>      return ff_make_absolute_url2(buf, size, base, rel, HAVE_DOS_PATHS);
>  }
> 
> +int ff_percent_encode_url(char *buf, int size, const char *url)
> +{
> +    const char *hex = "0123456789abcdef";
> +
> +    av_assert0(url);
> +
> +    int p = 0;
> +    int len = strlen(url);
> +    for (int i = 0; i < len; i++) {

What about the slash:

> +        if (i + 1 < len && ':' == url[i] && '/' == url[i+1])
> +            buf[p++] = url[i];


> +        else if (('a' <= url[i] && url[i] <= 'z')
> +          || ('A' <= url[i] && url[i] <= 'Z')
> +          || ('0' <= url[i] && url[i] <= '9')
> +          || '/' == url[i] || '.' == url[i] || '~' == url[i]
> +          || '-' == url[i] || '_' == url[i] || '+' == url[i]
> +          || '?' == url[i] || '=' == url[i] || '&' == url[i]
> +          || '#' == url[i])
> +        {
> +            buf[p++] = url[i];
> +        } else if (' ' == url[i])
> +        {

Space must be %20. The plus sign is only used for encoding form fields.

> +            buf[p++] = '+';
> +        } else
> +        {

Check buffer size:

> +            buf[p++] = '%';


Use HEX for upper case:

> +            buf[p++] = hex[url[i] >> 4];
> +            buf[p++] = hex[url[i] & 15];

> +            }
> +    }

Check buffer size:

> +    buf[p] = '\0';
> +
> +    return 0;
> +}
> +


Please also check behavior with signed/unsigned char, I'm not sure 
whether the shifts are always right.

As a tip: using AVBPrint for building the string might be easier.
HLS URLs can be pretty long sometimes.

Regards
sw
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