max_file_size_bytes = 0 counts as limited file size

[nakoo]

Background information

• Dendrite version or git SHA: 0.8.2
• Monolith or Polylith?: Monolith
• SQLite3 or Postgres?: Postgres
• Running in Docker?: Yes
• go version: -
• Client used (if applicable): Element Web

Description

• What is the problem:
  When max_file_size_bytes to 0, uploading file doesn't count as unlimited as intended. Fetching file from other servers counts as unlimited.

• Who is affected: -

• How is this bug manifesting:

• When did this first appear:
  Set max_file_size_bytes to 0 in dendrite.yaml config file

Steps to reproduce

• Set max_file_size_bytes to 0 in dendrite.yaml config file
• Restart the server
• Try to upload the file

[spaetz]

Is that not rather a client issue? The spec says:

m.upload.size integer The maximum size an upload can be in bytes. Clients SHOULD use this as a guide when uploading content. If not listed or null, the size limit should be treated as unknown.

Or does 'null' not include zero in this case?

[nakoo]

Is that not rather a client issue? The spec says:

m.upload.size integer The maximum size an upload can be in bytes. Clients SHOULD use this as a guide when uploading content. If not listed or null, the size limit should be treated as unknown.

Or does 'null' not include zero in this case?

It seems checkPositive function checks 0.

dendrite/setup/config/config_mediaapi.go

Line 64 in a84f50f

checkPositive(configErrs, "media_api.max_file_size_bytes", int64(*c.MaxFileSizeBytes))

dendrite/setup/config/config.go

Lines 383 to 387 in a84f50f

	func checkPositive(configErrs *ConfigErrors, key string, value int64) {
	if value < 0 {
	configErrs.Add(fmt.Sprintf("invalid value for config key %q: %d", key, value))
	}
	}

We need to document this part correctly as I mentioned if using 0 is not intended.
(same with build/docker/config/dendrite.yaml)

dendrite/dendrite-config.yaml

Lines 261 to 264 in bfa344e

	# The maximum allowed file size (in bytes) for media uploads to this homeserver
	# (0 = unlimited). If using a reverse proxy, ensure it allows requests at
	# least this large (e.g. client_max_body_size in nginx.)
	max_file_size_bytes: 10485760