[BUG] Attachments are not recognized at receiver

[codecivil]

Description

Attachments sent by axolotl on my ubuntu touch phone are received without filename or mimetype info. Downloading and renaming the attachment is a workaround (if you know the filetype a priori).

Steps to Reproduce

1. Attach a photo, document (or presumably also a audio or video file) to a message and send it.

Expected behavior: [What you expect to happen]
The receiver using the official Signal App sees the attachment (of supported type) and can click it to see the image/play the video etc.

Actual behavior: [What actually happens]
The receiver sees a nameless attachment of indeterminate filetype, e.g. a "MacBinary" instead of a JPEG on an iPhone. The receiver cannot open the attachment inside the Signal app but can download it.

I am not enough into Rust to be able to create a pull request but maybe constructing an automatic filename with the correct suffix in lines 1188 and 1272 of handlers.rs instead of "file_name: None" might resolve the issue; this might also be nonsense, however.

Versions

Axolotl Beta

Device

Ubuntu Touch on Sony Xperia X