148 lines
4.6 KiB
Go
148 lines
4.6 KiB
Go
package middleware
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import (
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"context"
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"errors"
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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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// PreHooks and PostHooks both use the same interface.
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//
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// A Hook can implement stop.Stopper if clean shutdown is required.
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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 && !errors.Is(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 && !errors.Is(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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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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// Add the Scrape data to the response.
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s := h.store.ScrapeSwarm(req.InfoHash, req.IP.AddressFamily)
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resp.Incomplete = s.Incomplete
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resp.Complete = s.Complete
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err = h.appendPeers(req, resp)
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return ctx, err
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}
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func (h *responseHook) appendPeers(req *bittorrent.AnnounceRequest, resp *bittorrent.AnnounceResponse) error {
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seeding := req.Left == 0
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peers, err := h.store.AnnouncePeers(req.InfoHash, seeding, int(req.NumWant), req.Peer)
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if err != nil && !errors.Is(err, storage.ErrResourceDoesNotExist) {
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return err
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}
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// Some clients expect a minimum of their own peer representation returned to
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// them if they are the only peer in a swarm.
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if len(peers) == 0 {
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if seeding {
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resp.Complete++
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} else {
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resp.Incomplete++
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}
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peers = append(peers, req.Peer)
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}
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switch req.IP.AddressFamily {
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case bittorrent.IPv4:
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resp.IPv4Peers = peers
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case bittorrent.IPv6:
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resp.IPv6Peers = peers
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default:
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panic("attempted to append peer that is neither IPv4 nor IPv6")
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}
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return 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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for _, infoHash := range req.InfoHashes {
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resp.Files = append(resp.Files, h.store.ScrapeSwarm(infoHash, req.AddressFamily))
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}
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return ctx, nil
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}
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