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Default validator support (libp2p#525)
* add default validator support * add an implementation for basic seqno as nonce validation * missing return * the nonce belongs to the origin peer * add note about rust predicament * add seqno validator tests * minor test tweak, ensure at least 1ms before replay
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,101 @@ | ||
| package pubsub | ||
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| import ( | ||
| "context" | ||
| "encoding/binary" | ||
| "sync" | ||
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| "github.com/libp2p/go-libp2p/core/peer" | ||
| ) | ||
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| // PeerMetadataStore is an interface for storing and retrieving per peer metadata | ||
| type PeerMetadataStore interface { | ||
| // Get retrieves the metadata associated with a peer; | ||
| // It should return nil if there is no metadata associated with the peer and not an error. | ||
| Get(context.Context, peer.ID) ([]byte, error) | ||
| // Put sets the metadata associated with a peer. | ||
| Put(context.Context, peer.ID, []byte) error | ||
| } | ||
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| // BasicSeqnoValidator is a basic validator, usable as a default validator, that ignores replayed | ||
| // messages outside the seen cache window. The validator uses the message seqno as a peer-specific | ||
| // nonce to decide whether the message should be propagated, comparing to the maximal nonce store | ||
| // in the peer metadata store. This is useful to ensure that there can be no infinitely propagating | ||
| // messages in the network regardless of the seen cache span and network diameter. | ||
| // It requires that pubsub is instantiated with a strict message signing policy and that seqnos | ||
| // are not disabled, ie it doesn't support anonymous mode. | ||
| // | ||
| // Warning: See https://github.com/libp2p/rust-libp2p/issues/3453 | ||
| // TL;DR: rust is currently violating the spec by issuing a random seqno, which creates an | ||
| // interoperability hazard. We expect this issue to be addressed in the not so distant future, | ||
| // but keep this in mind if you are in a mixed environment with (older) rust nodes. | ||
| type BasicSeqnoValidator struct { | ||
| mx sync.RWMutex | ||
| meta PeerMetadataStore | ||
| } | ||
|
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| // NewBasicSeqnoValidator constructs a BasicSeqnoValidator using the givven PeerMetadataStore. | ||
| func NewBasicSeqnoValidator(meta PeerMetadataStore) ValidatorEx { | ||
| val := &BasicSeqnoValidator{ | ||
| meta: meta, | ||
| } | ||
| return val.validate | ||
| } | ||
|
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| func (v *BasicSeqnoValidator) validate(ctx context.Context, _ peer.ID, m *Message) ValidationResult { | ||
| p := m.GetFrom() | ||
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| v.mx.RLock() | ||
| nonceBytes, err := v.meta.Get(ctx, p) | ||
| v.mx.RUnlock() | ||
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| if err != nil { | ||
| log.Warn("error retrieving peer nonce: %s", err) | ||
| return ValidationIgnore | ||
| } | ||
|
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| var nonce uint64 | ||
| if len(nonceBytes) > 0 { | ||
| nonce = binary.BigEndian.Uint64(nonceBytes) | ||
| } | ||
|
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| var seqno uint64 | ||
| seqnoBytes := m.GetSeqno() | ||
| if len(seqnoBytes) > 0 { | ||
| seqno = binary.BigEndian.Uint64(seqnoBytes) | ||
| } | ||
|
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| // compare against the largest seen nonce | ||
| if seqno <= nonce { | ||
| return ValidationIgnore | ||
| } | ||
|
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| // get the nonce and compare again with an exclusive lock before commiting (cf concurrent validation) | ||
| v.mx.Lock() | ||
| defer v.mx.Unlock() | ||
|
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| nonceBytes, err = v.meta.Get(ctx, p) | ||
| if err != nil { | ||
| log.Warn("error retrieving peer nonce: %s", err) | ||
| return ValidationIgnore | ||
| } | ||
|
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| if len(nonceBytes) > 0 { | ||
| nonce = binary.BigEndian.Uint64(nonceBytes) | ||
| } | ||
|
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| if seqno <= nonce { | ||
| return ValidationIgnore | ||
| } | ||
|
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| // update the nonce | ||
| nonceBytes = make([]byte, 8) | ||
| binary.BigEndian.PutUint64(nonceBytes, seqno) | ||
|
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| err = v.meta.Put(ctx, p, nonceBytes) | ||
| if err != nil { | ||
| log.Warn("error storing peer nonce: %s", err) | ||
| } | ||
|
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| return ValidationAccept | ||
| } |
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