No preview for meduza.io articles

[rkfg]

Description

There's no preview image for any article from meduza.io news site.

Steps to reproduce

• post an url like https://meduza.io/slides/vokrug-shum-rekordnyy-snegopad-v-moskve
• only the title and text is shown in the preview without the image

Server drops a line in the log:

2018-02-06 15:31:22,234 - synapse.rest.media.v1.preview_url_resource - 238 - WARNING - GET-12191- Couldn't get dims for https://meduza.io/imgly/share/1517844117/slides/vokrug-shum-rekordnyy-snegopad-v-moskve

The image itself is quite fine, it's a PNG of size 1200x630.

Version information

• Homeserver: own homeserver
• Version: Synapse/0.26.0
• Install method: package manager
• Platform: set up on Debian 9.3 amd64.

[neilisfragile]

$ curl https://meduza.io/imgly/share/1517844117/slides/vokrug-shum-rekordnyy-snegopad-v-moskve > image
$ identify image
image JPEG 1200x630 1200x630+0+0 8-bit sRGB 126632B 0.000u 0:00.000

Not clear on first pass why dims cannot be extracted

[rkfg]

So for this article above I have a preview image now. But this one's broken (as well as other more recent articles): https://meduza.io/feature/2021/04/07/proekt-rasskazal-o-vtoroy-zhene-ramzana-kadyrova-i-novoy-lichnosti-ego-pervoy-suprugi

The issue is that their server sends content-type as image/jpeg; charset=utf-8 which is weird but not against the spec I guess. It can be fixed in this file like this:

                 if b"Content-Type" in headers:
                     media_type = headers[b"Content-Type"][0].decode("ascii")
+                    scpos = media_type.find(';')
+                    if scpos > 0:
+                        media_type = media_type[:scpos]
                 else:
                     media_type = "application/octet-stream"

[clokep]

@rkfg Any chance you'd be willing to put up a PR? tests/rest/media/v1/test_url_preview.py has some tests which could be updated too.

[rkfg]

I'll see what I can do. There's another issue that prevents the preview images for pikabu.ru from showing, around this line:

         jpeg_thumbnail = ThumbnailRequirement(width, height, method, "image/jpeg")
         png_thumbnail = ThumbnailRequirement(width, height, method, "image/png")
         requirements.setdefault("image/jpeg", []).append(jpeg_thumbnail)
+        requirements.setdefault("image/jpg", []).append(jpeg_thumbnail)
         requirements.setdefault("image/webp", []).append(jpeg_thumbnail)
         requirements.setdefault("image/gif", []).append(png_thumbnail)
         requirements.setdefault("image/png", []).append(png_thumbnail)

Their content-type for the previews is image/jpg which seems not to be standard conforming but the Internet is a mess and we have to deal with it. Should I also add this change to the PR?

[clokep]

It seems related enough to more robust handling of the Content-Type header, so sure.