143 lines
4.5 KiB
Go
143 lines
4.5 KiB
Go
package middleware
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import (
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"context"
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"errors"
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"net"
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"github.com/chihaya/chihaya/bittorrent"
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"github.com/chihaya/chihaya/storage"
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)
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// Hook abstracts the concept of anything that needs to interact with a
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// BitTorrent client's request and response to a BitTorrent tracker.
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type Hook interface {
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HandleAnnounce(context.Context, *bittorrent.AnnounceRequest, *bittorrent.AnnounceResponse) (context.Context, error)
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HandleScrape(context.Context, *bittorrent.ScrapeRequest, *bittorrent.ScrapeResponse) (context.Context, error)
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}
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type skipSwarmInteraction struct{}
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// SkipSwarmInteractionKey is a key for the context of an Announce to control
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// whether the swarm interaction middleware should run.
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// Any non-nil value set for this key will cause the swarm interaction
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// middleware to skip.
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var SkipSwarmInteractionKey = skipSwarmInteraction{}
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type swarmInteractionHook struct {
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store storage.PeerStore
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}
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func (h *swarmInteractionHook) HandleAnnounce(ctx context.Context, req *bittorrent.AnnounceRequest, resp *bittorrent.AnnounceResponse) (_ context.Context, err error) {
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if ctx.Value(SkipSwarmInteractionKey) != nil {
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return ctx, nil
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}
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switch {
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case req.Event == bittorrent.Stopped:
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err = h.store.DeleteSeeder(req.InfoHash, req.Peer)
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if err != nil && err != storage.ErrResourceDoesNotExist {
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return ctx, err
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}
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err = h.store.DeleteLeecher(req.InfoHash, req.Peer)
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if err != nil && err != storage.ErrResourceDoesNotExist {
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return ctx, err
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}
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case req.Event == bittorrent.Completed:
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err = h.store.GraduateLeecher(req.InfoHash, req.Peer)
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return ctx, err
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case req.Left == 0:
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// Completed events will also have Left == 0, but by making this
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// an extra case we can treat "old" seeders differently from
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// graduating leechers. (Calling PutSeeder is probably faster
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// than calling GraduateLeecher.)
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err = h.store.PutSeeder(req.InfoHash, req.Peer)
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return ctx, err
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default:
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err = h.store.PutLeecher(req.InfoHash, req.Peer)
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return ctx, err
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}
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return ctx, nil
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}
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func (h *swarmInteractionHook) HandleScrape(ctx context.Context, _ *bittorrent.ScrapeRequest, _ *bittorrent.ScrapeResponse) (context.Context, error) {
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// Scrapes have no effect on the swarm.
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return ctx, nil
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}
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// ErrInvalidIP indicates an invalid IP for an Announce.
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var ErrInvalidIP = errors.New("invalid IP")
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type skipResponseHook struct{}
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// SkipResponseHookKey is a key for the context of an Announce or Scrape to
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// control whether the response middleware should run.
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// Any non-nil value set for this key will cause the response middleware to
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// skip.
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var SkipResponseHookKey = skipResponseHook{}
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type scrapeAddressType struct{}
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// ScrapeIsIPv6Key is the key under which to store whether or not the
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// address used to request a scrape was an IPv6 address.
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// The value is expected to be of type bool.
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// A missing value or a value that is not a bool for this key is equivalent to
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// it being set to false.
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var ScrapeIsIPv6Key = scrapeAddressType{}
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type responseHook struct {
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store storage.PeerStore
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}
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func (h *responseHook) HandleAnnounce(ctx context.Context, req *bittorrent.AnnounceRequest, resp *bittorrent.AnnounceResponse) (_ context.Context, err error) {
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if ctx.Value(SkipResponseHookKey) != nil {
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return ctx, nil
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}
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s := h.store.ScrapeSwarm(req.InfoHash, len(req.IP) == net.IPv6len)
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resp.Incomplete = s.Incomplete
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resp.Complete = s.Complete
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switch len(req.IP) {
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case net.IPv4len:
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resp.IPv4Peers, err = h.getPeers(req.InfoHash, req.Left == 0, int(req.NumWant), req.Peer)
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case net.IPv6len:
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resp.IPv6Peers, err = h.getPeers(req.InfoHash, req.Left == 0, int(req.NumWant), req.Peer)
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default:
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return ctx, ErrInvalidIP
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}
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return ctx, err
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}
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func (h *responseHook) getPeers(ih bittorrent.InfoHash, seeder bool, numWant int, p bittorrent.Peer) ([]bittorrent.Peer, error) {
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peers, err := h.store.AnnouncePeers(ih, seeder, numWant, p)
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if err != nil && err != storage.ErrResourceDoesNotExist {
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return nil, err
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}
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// Insert announcing peer.
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// Some clients expect at least themselves in every announce response.
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if len(peers) < numWant || len(peers) == 0 {
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return append(peers, p), nil
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}
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peers[len(peers)-1] = p
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return peers, nil
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}
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func (h *responseHook) HandleScrape(ctx context.Context, req *bittorrent.ScrapeRequest, resp *bittorrent.ScrapeResponse) (context.Context, error) {
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if ctx.Value(SkipResponseHookKey) != nil {
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return ctx, nil
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}
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v6, _ := ctx.Value(ScrapeIsIPv6Key).(bool)
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for _, infoHash := range req.InfoHashes {
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resp.Files[infoHash] = h.store.ScrapeSwarm(infoHash, v6)
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}
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return ctx, nil
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}
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