-Store and share torrent-like strings for large files.
-
-In addition to storing the file download location (which would still be
-used for small files), a bencoded dictionary containing the peer's
-hashes of the individual pieces could be stored for the larger files
-(20% of all the files are larger than 512 KB). This dictionary would
-have the normal piece size, the hash length, and a string containing the
-piece hashes of length <hash length>*<#pieces>. These piece hashes could
-be compared ahead of time to determine which peers have the same piece
-hashes (they all should), and then used during the download to verify
-the downloaded pieces.
-
-For very large files (5 or more pieces), the torrent strings are too
-long to store in the DHT and retrieve (a single UDP packet should be
-less than 1472 bytes to avoid fragmentation). Instead, the peers should
-store the torrent-like string for large files separately, and only
-contain a reference to it in their stored value for the hash of the
-file. The reference would be a hash of the bencoded dictionary. If the
-torrent-like string is short enough to store in the DHT (i.e. less than
-1472 bytes, or about 70 pieces for the SHA1 hash), then a
-lookup of that hash in the DHT would give the torrent-like string.
-Otherwise, a request to the peer for the hash (just like files are
-downloaded), should return the bencoded torrent-like string.
-
-
-PeerManager needs to track peers' properties.
-
-The PeerManager needs to keep track of the observed properties of seen
-peers, to help determine a selection criteria for choosing peers to
-download from. Each property will give a value from 0 to 1. The relevant
-properties are:
-
- - hash errors in last day (1 = 0, 0 = 3+)
- - recent download speed (1 = fastest, 0 = 0)
- - lag time from request to download (1 = 0, 0 = 15s+)
- - number of pending requests (1 = 0, 0 = max (10))
- - whether a connection is open (1 = yes, 0.9 = no)
-
-These should be combined (multiplied) to provide a sort order for peers
-available to download from, which can then be used to assign new
-downloads to peers. Pieces should be downloaded from the best peers
-first (i.e. piece 0 from the absolute best peer).
-
-
-Missing Kademlia implementation details are needed.
-
-The current implementation is missing some important features, mostly
-focussed on storing values:
- - values need to be republished (every hour?)
- - original publishers need to republish values (every 24 hours)
- - when a new node is found that is closer to some values, replicate the
- values there without deleting them
- - when a value lookup succeeds, store the value in the closest node
- found that didn't have it
- - make the expiration time of a value exponentially inversely
- proportional to the number of nodes between the current node and the
- node closest to the value
+Consider storing deltas of packages.
+
+Instead of downloading full package files when a previous version of
+the same package is available, peers could request a delta of the
+package to the previous version. This would only be done if the delta
+is significantly (>50%) smaller than the full package, and is not too
+large (absolutely). A peer that has a new package and an old one would
+add a list of deltas for the package to the value stored in the DHT.
+The delta information would specify the old version (by hash), the
+size of the delta, and the hash of the delta. A peer that has the same
+old package could then download the delta from the peer by requesting
+the hash of the delta. Alternatively, very small deltas could be
+stored directly in the DHT.
+
+
+Consider tracking security issues with packages.
+
+Since sharing information with others about what packages you have
+downloaded (and probably installed) is a possible security
+vulnerability, it would be advantageous to not share that information
+for packages that have known security vulnerabilities. This would
+require some way of obtaining a list of which packages (and versions)
+are vulnerable, which is not currently available.
+
+
+Consider adding peer characteristics to the DHT.
+
+Bad peers could be indicated in the DHT by adding a new value that is
+the NOT of their ID (so they are guaranteed not to store it) indicating
+information about the peer. This could be bad votes on the peer, as
+otherwise a peer could add good info about itself.
+
+
+Consider adding pieces to the DHT instead of files.
+
+Instead of adding file hashes to the DHT, only piece hashes could be
+added. This would allow a peer to upload to other peers while it is
+still downloading the rest of the file. It is not clear that this is
+needed, since peer's will not be uploading and downloading ery much of
+the time.
projects / quix0rs-apt-p2p.git / blobdiff