Module tox_core::onion

Onion module allows nodes to announce their long term public keys and find friends by their long term public keys.

There are two basic onion requests - OnionAnnounceRequest and OnionDataRequest. They are enclosed to OnionRequest packets and sent though the onion path to prevent nodes finding out long term public key when they know only temporary DHT public key. There are three types of OnionRequest packets: OnionRequest0, OnionRequest1 and OnionRequest2. OnionAnnounceRequest and OnionDataRequest when created are enclosed to OnionRequest2, OnionRequest2 is enclosed to OnionRequest1 and OnionRequest1 is enclosed to OnionRequest0. When DHT node receives OnionRequest packet it decrypts inner packet and sends it to the next node.

+--------+                       +--------+                       +--------+                       +--------+   +----------------------+   +------------+
|        |   +---------------+   |        |   +---------------+   |        |   +---------------+   |        |   | OnionAnnounceRequest |   |            |
| Sender |---| OnionRequest0 |-->| Node 1 |---| OnionRequest1 |-->| Node 2 |---| OnionRequest2 |-->| Node 3 |---+----------------------+-->| Onion node |
|        |   +---------------+   |        |   +---------------+   |        |   +---------------+   |        |   | OnionDataRequest     |   |            |
+--------+                       +--------+                       +--------+                       +--------+   +----------------------+   +------------+

Similarly to requests there are responses OnionAnnounceResponse and OnionDataResponse that enclosed to three kind of OnionRespose packets: OnionResponse3, OnionResponse2 and OnionResponse1. OnionResponse packets are processed in the same way but with reverse ordering.

+------------+                        +--------+                        +--------+                        +--------+   +-----------------------+   +----------+
|            |   +----------------+   |        |   +----------------+   |        |   +----------------+   |        |   | OnionAnnounceResponse |   |          |
| Onion node |---| OnionResponse3 |-->| Node 3 |---| OnionResponse2 |-->| Node 2 |---| OnionResponse1 |-->| Node 1 |---+-----------------------+-->| Receiver |
|            |   +----------------+   |        |   +----------------+   |        |   +----------------+   |        |   | OnionDataResponse     |   |          |
+------------+                        +--------+                        +--------+                        +--------+   +-----------------------+   +----------+

When onion node handles OnionAnnounceRequest packet it sends answer to original sender using the same onion path with the help of received onion return addresses. But when it handles OnionDataRequest packet it should send response packet to another destination node by its long term public key. That means that when onion node should store long term public keys of announced node along with onion return addresses.

Modules

client	Onion client implementation.
onion_announce	The implementation of onion announce