Be more lenient in the oEmbed response parsing. (#14089)

Attempt to parse any valid information from an oEmbed response
(instead of bailing at the first unexpected data). This should allow
for more partial oEmbed data to be returned, resulting in better /
more URL previews, even if those URL previews are only partial.

1 files changed, 57 insertions, 50 deletions

diff --git a/synapse/rest/media/v1/oembed.py b/synapse/rest/media/v1/oembed.py

index 2177b46c9e..827afd868d 100644
--- a/synapse/rest/media/v1/oembed.py
+++ b/synapse/rest/media/v1/oembed.py
@@ -139,65 +139,72 @@ class OEmbedProvider:
         try:
             # oEmbed responses *must* be UTF-8 according to the spec.
             oembed = json_decoder.decode(raw_body.decode("utf-8"))
+        except ValueError:
+            return OEmbedResult({}, None, None)
 
-            # The version is a required string field, but not always provided,
-            # or sometimes provided as a float. Be lenient.
-            oembed_version = oembed.get("version", "1.0")
-            if oembed_version != "1.0" and oembed_version != 1:
-                raise RuntimeError(f"Invalid oEmbed version: {oembed_version}")
+        # The version is a required string field, but not always provided,
+        # or sometimes provided as a float. Be lenient.
+        oembed_version = oembed.get("version", "1.0")
+        if oembed_version != "1.0" and oembed_version != 1:
+            return OEmbedResult({}, None, None)
 
-            # Ensure the cache age is None or an int.
-            cache_age = oembed.get("cache_age")
-            if cache_age:
-                cache_age = int(cache_age) * 1000
-
-            # The results.
-            open_graph_response = {
-                "og:url": url,
-            }
-
-            title = oembed.get("title")
-            if title:
-                open_graph_response["og:title"] = title
-
-            author_name = oembed.get("author_name")
+        # Attempt to parse the cache age, if possible.
+        try:
+            cache_age = int(oembed.get("cache_age")) * 1000
+        except (TypeError, ValueError):
+            # If the cache age cannot be parsed (e.g. wrong type or invalid
+            # string), ignore it.
+            cache_age = None
 
-            # Use the provider name and as the site.
-            provider_name = oembed.get("provider_name")
-            if provider_name:
-                open_graph_response["og:site_name"] = provider_name
+        # The oEmbed response converted to Open Graph.
+        open_graph_response: JsonDict = {"og:url": url}
 
-            # If a thumbnail exists, use it. Note that dimensions will be calculated later.
-            if "thumbnail_url" in oembed:
-                open_graph_response["og:image"] = oembed["thumbnail_url"]
+        title = oembed.get("title")
+        if title and isinstance(title, str):
+            open_graph_response["og:title"] = title
 
-            # Process each type separately.
-            oembed_type = oembed["type"]
-            if oembed_type == "rich":
-                calc_description_and_urls(open_graph_response, oembed["html"])
-
-            elif oembed_type == "photo":
-                # If this is a photo, use the full image, not the thumbnail.
-                open_graph_response["og:image"] = oembed["url"]
+        author_name = oembed.get("author_name")
+        if not isinstance(author_name, str):
+            author_name = None
 
-            elif oembed_type == "video":
-                open_graph_response["og:type"] = "video.other"
+        # Use the provider name and as the site.
+        provider_name = oembed.get("provider_name")
+        if provider_name and isinstance(provider_name, str):
+            open_graph_response["og:site_name"] = provider_name
+
+        # If a thumbnail exists, use it. Note that dimensions will be calculated later.
+        thumbnail_url = oembed.get("thumbnail_url")
+        if thumbnail_url and isinstance(thumbnail_url, str):
+            open_graph_response["og:image"] = thumbnail_url
+
+        # Process each type separately.
+        oembed_type = oembed.get("type")
+        if oembed_type == "rich":
+            html = oembed.get("html")
+            if isinstance(html, str):
+                calc_description_and_urls(open_graph_response, html)
+
+        elif oembed_type == "photo":
+            # If this is a photo, use the full image, not the thumbnail.
+            url = oembed.get("url")
+            if url and isinstance(url, str):
+                open_graph_response["og:image"] = url
+
+        elif oembed_type == "video":
+            open_graph_response["og:type"] = "video.other"
+            html = oembed.get("html")
+            if html and isinstance(html, str):
                 calc_description_and_urls(open_graph_response, oembed["html"])
-                open_graph_response["og:video:width"] = oembed["width"]
-                open_graph_response["og:video:height"] = oembed["height"]
-
-            elif oembed_type == "link":
-                open_graph_response["og:type"] = "website"
+            for size in ("width", "height"):
+                val = oembed.get(size)
+                if val is not None and isinstance(val, int):
+                    open_graph_response[f"og:video:{size}"] = val
 
-            else:
-                raise RuntimeError(f"Unknown oEmbed type: {oembed_type}")
+        elif oembed_type == "link":
+            open_graph_response["og:type"] = "website"
 
-        except Exception as e:
-            # Trap any exception and let the code follow as usual.
-            logger.warning("Error parsing oEmbed metadata from %s: %r", url, e)
-            open_graph_response = {}
-            author_name = None
-            cache_age = None
+        else:
+            logger.warning("Unknown oEmbed type: %s", oembed_type)
 
         return OEmbedResult(open_graph_response, author_name, cache_age)