[FFmpeg-devel] [PATCH] Allow mpjpeg demuxer to process MIME parts which do not include Content-Length header.

[wm4]

On Wed, 25 Nov 2015 10:35:31 -0500
Alex Agranovsky <alex at sighthound.com> wrote:

> From 4797590e11267993c3883e5037619625e1f1dadf Mon Sep 17 00:00:00 2001
> From: Alex Agranovsky <alex at sighthound.com>
> Date: Tue, 24 Nov 2015 00:07:34 -0500
> Subject: [PATCH 2/2] If available, use the actual boundary in HTTP response's
>  Content-Type header, to separate MIME parts in mpjpeg stream
> 
> This code is disabled by default so not to regress endpoints sending invalid MIME, but can be enabled via AVOption 'strict_mime_boundary'
> 
> Signed-off-by: Alex Agranovsky <alex at sighthound.com>
> ---
>  libavformat/mpjpegdec.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 73 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/mpjpegdec.c b/libavformat/mpjpegdec.c
> index b9093ea..c0f011d 100644
> --- a/libavformat/mpjpegdec.c
> +++ b/libavformat/mpjpegdec.c
> @@ -20,6 +20,7 @@
>   */
>  
>  #include "libavutil/avstring.h"
> +#include "libavutil/opt.h"
>  
>  #include "avformat.h"
>  #include "internal.h"
> @@ -28,9 +29,11 @@
>  
>  
>  typedef struct MPJPEGDemuxContext {
> +    const AVClass *class;
>      char*       boundary;
>      char*       searchstr;
>      int         searchstr_len;
> +    int         strict_mime_boundary;
>  } MPJPEGDemuxContext;
>  
>  
> @@ -245,6 +248,43 @@ static int parse_multipart_header(AVIOContext *pb,
>  }
>  
>  
> +static char* mpjpeg_get_boundary(AVIOContext* pb)
> +{
> +    uint8_t *mime_type = NULL;
> +    uint8_t *start;
> +    uint8_t *end;
> +    uint8_t *res = NULL;
> +    int     len;
> +
> +    /* get MIME type, and skip to the first parameter */
> +    av_opt_get(pb, "mime_type", AV_OPT_SEARCH_CHILDREN, &mime_type);
> +    start = mime_type;
> +    while (start != NULL && *start != '\0') {
> +        start = strchr(start, ';');
> +        if (start)
> +            start = start+1;
> +
> +        while (av_isspace(*start))
> +            start++;
> +
> +        if (!av_strncasecmp(start, "boundary=", 9)) {
> +            start += 9;

(Probably could use av_strstart() here, but you don't need to change it
if you don't want to.)

> +
> +            end = strchr(start, ';');
> +            if (end)
> +                len = end - start - 1;
> +            else
> +                len = strlen(start);
> +            res = av_strndup(start, len);
> +            break;
> +        }
> +    }
> +
> +    av_freep(&mime_type);
> +    return res;
> +}
> +
> +
>  static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
>  {
>      int size;
> @@ -252,8 +292,19 @@ static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
>  
>      MPJPEGDemuxContext *mpjpeg = s->priv_data;
>      if (mpjpeg->boundary == NULL) {
> -        mpjpeg->boundary = av_strdup("--");
> -        mpjpeg->searchstr = av_strdup("\r\n--");
> +        uint8_t* boundary = NULL;
> +        if (mpjpeg->strict_mime_boundary) {
> +            boundary = mpjpeg_get_boundary(s->pb);
> +        }
> +        if (boundary != NULL) {
> +            size_t bufsize = 4+strlen(boundary)+1;
> +            mpjpeg->boundary = boundary;
> +            mpjpeg->searchstr = av_malloc(bufsize);
> +            snprintf( mpjpeg->searchstr, bufsize, "\r\n%s\r\n", boundary );

av_asprintf() would be much more convenient.

> +        } else {
> +            mpjpeg->boundary = av_strdup("--");
> +            mpjpeg->searchstr = av_strdup("\r\n--");
> +        }
>          mpjpeg->searchstr_len = strlen(mpjpeg->searchstr);
>          if (!mpjpeg->boundary || !mpjpeg->searchstr) {
>              av_freep(&mpjpeg->boundary);
> @@ -315,6 +366,22 @@ static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
>      return ret;
>  }
>  
> +#define OFFSET(x) offsetof(MPJPEGDemuxContext, x)
> +
> +#define DEC AV_OPT_FLAG_DECODING_PARAM
> +const AVOption mpjpeg_options[] = {
> +    { "strict_mime_boundary",  "require MIME boundaries match", OFFSET(strict_mime_boundary), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, DEC },

Not sure, but maybe it'd be good to have a better explanation for this
option in doc/demuxers.texi.

> +    { NULL }
> +};
> +
> +
> +static const AVClass mpjpeg_demuxer_class = {
> +    .class_name     = "MPJPEG demuxer",
> +    .item_name      = av_default_item_name,
> +    .option         = mpjpeg_options,
> +    .version        = LIBAVUTIL_VERSION_INT,
> +};
> +
>  AVInputFormat ff_mpjpeg_demuxer = {
>      .name              = "mpjpeg",
>      .long_name         = NULL_IF_CONFIG_SMALL("MIME multipart JPEG"),
> @@ -324,5 +391,8 @@ AVInputFormat ff_mpjpeg_demuxer = {
>      .read_probe        = mpjpeg_read_probe,
>      .read_header       = mpjpeg_read_header,
>      .read_packet       = mpjpeg_read_packet,
> -    .read_close        = mpjpeg_read_close
> +    .read_close        = mpjpeg_read_close,
> +    .priv_class        = &mpjpeg_demuxer_class
>  };
> +
> +

Rest looks good to me.