86 lines
2.0 KiB
Go
86 lines
2.0 KiB
Go
package discovery
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import (
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"context"
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"time"
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cid "github.com/ipfs/go-cid"
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"github.com/libp2p/go-libp2p-core/peer"
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"github.com/libp2p/go-libp2p-core/routing"
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mh "github.com/multiformats/go-multihash"
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)
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// RoutingDiscovery is an implementation of discovery using ContentRouting
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// Namespaces are translated to Cids using the SHA256 hash.
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type RoutingDiscovery struct {
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routing.ContentRouting
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}
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func NewRoutingDiscovery(router routing.ContentRouting) *RoutingDiscovery {
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return &RoutingDiscovery{router}
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}
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func (d *RoutingDiscovery) Advertise(ctx context.Context, ns string, opts ...Option) (time.Duration, error) {
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var options Options
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err := options.Apply(opts...)
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if err != nil {
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return 0, err
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}
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ttl := options.Ttl
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if ttl == 0 || ttl > 3*time.Hour {
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// the DHT provider record validity is 24hrs, but it is recommnded to republish at least every 6hrs
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// we go one step further and republish every 3hrs
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ttl = 3 * time.Hour
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}
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cid, err := nsToCid(ns)
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if err != nil {
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return 0, err
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}
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// this context requires a timeout; it determines how long the DHT looks for
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// closest peers to the key/CID before it goes on to provide the record to them.
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// Not setting a timeout here will make the DHT wander forever.
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pctx, cancel := context.WithTimeout(ctx, 60*time.Second)
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defer cancel()
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err = d.Provide(pctx, cid, true)
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if err != nil {
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return 0, err
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}
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return ttl, nil
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}
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func (d *RoutingDiscovery) FindPeers(ctx context.Context, ns string, opts ...Option) (<-chan peer.AddrInfo, error) {
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var options Options
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err := options.Apply(opts...)
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if err != nil {
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return nil, err
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}
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limit := options.Limit
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if limit == 0 {
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limit = 100 // that's just arbitrary, but FindProvidersAsync needs a count
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}
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cid, err := nsToCid(ns)
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if err != nil {
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return nil, err
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}
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return d.FindProvidersAsync(ctx, cid, limit), nil
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}
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func nsToCid(ns string) (cid.Cid, error) {
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h, err := mh.Sum([]byte(ns), mh.SHA2_256, -1)
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if err != nil {
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return cid.Undef, err
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}
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return cid.NewCidV1(cid.Raw, h), nil
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}
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