36 lines
1.1 KiB
Go
36 lines
1.1 KiB
Go
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// Contains the Whisper protocol Topic element. For formal details please see
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// the specs at https://github.com/ethereum/wiki/wiki/Whisper-PoC-1-Protocol-Spec#topics.
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package whisper
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import "github.com/ethereum/go-ethereum/crypto"
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// Topic represents a cryptographically secure, probabilistic partial
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// classifications of a message, determined as the first (left) 4 bytes of the
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// SHA3 hash of some arbitrary data given by the original author of the message.
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type Topic [4]byte
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// NewTopic creates a topic from the 4 byte prefix of the SHA3 hash of the data.
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func NewTopic(data []byte) Topic {
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prefix := [4]byte{}
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copy(prefix[:], crypto.Sha3(data)[:4])
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return Topic(prefix)
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}
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// String converts a topic byte array to a string representation.
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func (self *Topic) String() string {
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return string(self[:])
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}
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// TopicSet represents a hash set to check if a topic exists or not.
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type TopicSet map[string]struct{}
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// NewTopicSet creates a topic hash set from a slice of topics.
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func NewTopicSet(topics []Topic) TopicSet {
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set := make(map[string]struct{})
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for _, topic := range topics {
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set[topic.String()] = struct{}{}
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}
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return TopicSet(set)
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}
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