Originally I had hoped to do this by using an intermediate iframe, to keep the message handlers separate from the user content, but this created CORS issues of its own. This approach is far simpler.
Now that we require API key authentication - and therefore security is greatly improved - many users will want to bypass the whitelist in order for the UI to communicate with their remote node. This gives an easy way to do this, without having to override the default whitelist. This boolean can now optionally be added to the default settings.json that is published with new releases, without removing the code's ability to update default whitelist values.
This should fix issue where it would take up to 30 seconds to return for a recent block, and would consume masses of CPU due to having to base58 encode the online accounts signatures. Base58 is very slow and made this API endpoint almost unusable for recent blocks, due to them having untrimmed online accounts signatures.
The procedure outlined in commit f4b06fb is now incorrect. Updated procedure:
- A node can opt into relay mode via the "relayModeEnabled":true setting.
- From this time onwards, they will ask their peers if they ever receive a file list request that they cannot serve by themselves.
- Whenever a peer responds with a file list, it is forwarded on to the originally requesting peer, complete with the peer address of the node that responded. Currently, only the first response is forwarded, but we may later decide to forward all responses.
- As well as forwarding, the relay peer keeps track of the peers that report to be holding hashes (these mappings are held for 30 seconds).
- The originally requesting peer can then make a request to the relay peer for the data file(s).
- The relay peer uses the mapping to forward the request on to another peer, and then forwards the response (i.e. the data file) back to the peer that originally requested the file.
It's best that the source peer's address isn't exposed to the requesting peer. The relay peer can keep track of this mapping itself.
The only real issue with this approach is that we can't use data from ArbitraryDataFileListMessage to update our ArbitraryPeers data, because we can't distinguish between relay peers and hosting peers. But this isn't something we currently do anyway, as we have the ARBITRARY_SIGNATURES message type to take care of updating ArbitraryPeers mappings.
Setting this to false prevents new connections being made to peers that report to have the data that is needed. This is likely only useful for testing, as disabling it in production would reduce the success rate of data retrieval.
This reuses most of the code already in place in the core related to forwarding.
- A node can opt into relay mode via the "relayModeEnabled": true setting
- From this time onwards, they will ask their peers if they ever receive a file list request that they cannot serve by themselves
- Whenever a peer responds with a file list, it is forwarded on to the originally requesting peer, complete with the peer address of the node that responded
- The original peer can then make a request for the data file(s) themselves using a similar approach, specifying the IP address of the ultimate peer so that the relay node knows who to ask. This part is not implemented yet.
This makes them extremely generic, improves filenames, and makes it easier to create custom lists. It doesn't have backwards support, but the lists feature isn't working properly in core 2.1+ anyway.
