The autoupdate package provides Lantern with the ability to request,
download and apply software updates over the network with minimal interaction.
At this time, autoupdate relies on the go-update and the
autoupdate-server packages.
## General flow
At some point on the Lantern application's lifetime, an independent process will be created, this process will periodically send local information (using a proxy, if available) to an update server that will compare client's data against a list of releases. When applicable, the server will generate a binary patch and send a reply to the client containing the URL of the appropriate patch. The client will download and apply the patch to its executable file so the new version is ready the next time Lantern starts.
The update server holds a list of releases and waits for queries from clients. Clients will send their own checksum and the server will compare that checksum against the checksum of the latest release, if they don't match a binary diff will be generated. This binary diff can be used by the client to patch itself.
The update server may or may not be used as a download server. Clients will pull binary diffs from this location, the actual patch's URL will be provided by the update server.
A client will compute the checksum of its executable file and will send it to an update server periodically. When the update server replies with a special message meaning that a new version is available, the client will download the binary patch, apply it to a temporary file and check the signature, if the signature is what the client expects, the original executable will be replaced with the patched one.