status-go/wakuv2/common/topic.go

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// Copyright 2019 The Waku Library Authors.
//
// The Waku library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The Waku library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty off
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the Waku library. If not, see <http://www.gnu.org/licenses/>.
//
// This software uses the go-ethereum library, which is licensed
// under the GNU Lesser General Public Library, version 3 or any later.
package common
import (
"errors"
"strings"
"github.com/ethereum/go-ethereum/common/hexutil"
)
// TopicType represents a cryptographically secure, probabilistic partial
// classifications of a message, determined as the first (leftmost) 4 bytes of the
// SHA3 hash of some arbitrary data given by the original author of the message.
type TopicType [TopicLength]byte
// BytesToTopic converts from the byte array representation of a topic
// into the TopicType type.
func BytesToTopic(b []byte) (t TopicType) {
sz := TopicLength
if x := len(b); x < TopicLength {
sz = x
}
for i := 0; i < sz; i++ {
t[i] = b[i]
}
return t
}
func StringToTopic(s string) (t TopicType) {
str, _ := hexutil.Decode(s)
return BytesToTopic(str)
}
// String converts a topic byte array to a string representation.
func (t *TopicType) String() string {
return hexutil.Encode(t[:])
}
// MarshalText returns the hex representation of t.
func (t TopicType) MarshalText() ([]byte, error) {
return hexutil.Bytes(t[:]).MarshalText()
}
// UnmarshalText parses a hex representation to a topic.
func (t *TopicType) UnmarshalText(input []byte) error {
return hexutil.UnmarshalFixedText("Topic", input, t[:])
}
// Converts a topic to its 23/WAKU2-TOPICS representation
func (t TopicType) ContentTopic() string {
enc := hexutil.Encode(t[:])
return "/waku/1/" + enc + "/rfc26"
}
func ExtractTopicFromContentTopic(s string) (*TopicType, error) {
p := strings.Split(s, "/")
if len(p) != 5 || p[1] != "waku" || p[2] != "1" || p[4] != "rfc26" {
return nil, errors.New("invalid content topic format")
}
str, err := hexutil.Decode(p[3])
if err != nil {
return nil, err
}
result := BytesToTopic(str)
return &result, nil
}