github.com/SmartMeshFoundation/Spectrum@v0.0.0-20220621030607-452a266fee1e/whisper/whisperv2/filter.go (about)

     1  // Copyright 2014 The Spectrum Authors
     2  // This file is part of the Spectrum library.
     3  //
     4  // The Spectrum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The Spectrum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the Spectrum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  // Contains the message filter for fine grained subscriptions.
    18  
    19  package whisperv2
    20  
    21  import (
    22  	"crypto/ecdsa"
    23  
    24  	"github.com/SmartMeshFoundation/Spectrum/event/filter"
    25  )
    26  
    27  // Filter is used to subscribe to specific types of whisper messages.
    28  type Filter struct {
    29  	To     *ecdsa.PublicKey   // Recipient of the message
    30  	From   *ecdsa.PublicKey   // Sender of the message
    31  	Topics [][]Topic          // Topics to filter messages with
    32  	Fn     func(msg *Message) // Handler in case of a match
    33  }
    34  
    35  // NewFilterTopics creates a 2D topic array used by whisper.Filter from binary
    36  // data elements.
    37  func NewFilterTopics(data ...[][]byte) [][]Topic {
    38  	filter := make([][]Topic, len(data))
    39  	for i, condition := range data {
    40  		// Handle the special case of condition == [[]byte{}]
    41  		if len(condition) == 1 && len(condition[0]) == 0 {
    42  			filter[i] = []Topic{}
    43  			continue
    44  		}
    45  		// Otherwise flatten normally
    46  		filter[i] = NewTopics(condition...)
    47  	}
    48  	return filter
    49  }
    50  
    51  // NewFilterTopicsFlat creates a 2D topic array used by whisper.Filter from flat
    52  // binary data elements.
    53  func NewFilterTopicsFlat(data ...[]byte) [][]Topic {
    54  	filter := make([][]Topic, len(data))
    55  	for i, element := range data {
    56  		// Only add non-wildcard topics
    57  		filter[i] = make([]Topic, 0, 1)
    58  		if len(element) > 0 {
    59  			filter[i] = append(filter[i], NewTopic(element))
    60  		}
    61  	}
    62  	return filter
    63  }
    64  
    65  // NewFilterTopicsFromStrings creates a 2D topic array used by whisper.Filter
    66  // from textual data elements.
    67  func NewFilterTopicsFromStrings(data ...[]string) [][]Topic {
    68  	filter := make([][]Topic, len(data))
    69  	for i, condition := range data {
    70  		// Handle the special case of condition == [""]
    71  		if len(condition) == 1 && condition[0] == "" {
    72  			filter[i] = []Topic{}
    73  			continue
    74  		}
    75  		// Otherwise flatten normally
    76  		filter[i] = NewTopicsFromStrings(condition...)
    77  	}
    78  	return filter
    79  }
    80  
    81  // NewFilterTopicsFromStringsFlat creates a 2D topic array used by whisper.Filter from flat
    82  // binary data elements.
    83  func NewFilterTopicsFromStringsFlat(data ...string) [][]Topic {
    84  	filter := make([][]Topic, len(data))
    85  	for i, element := range data {
    86  		// Only add non-wildcard topics
    87  		filter[i] = make([]Topic, 0, 1)
    88  		if element != "" {
    89  			filter[i] = append(filter[i], NewTopicFromString(element))
    90  		}
    91  	}
    92  	return filter
    93  }
    94  
    95  // filterer is the internal, fully initialized filter ready to match inbound
    96  // messages to a variety of criteria.
    97  type filterer struct {
    98  	to      string                 // Recipient of the message
    99  	from    string                 // Sender of the message
   100  	matcher *topicMatcher          // Topics to filter messages with
   101  	fn      func(data interface{}) // Handler in case of a match
   102  }
   103  
   104  // Compare checks if the specified filter matches the current one.
   105  func (self filterer) Compare(f filter.Filter) bool {
   106  	filter := f.(filterer)
   107  
   108  	// Check the message sender and recipient
   109  	if len(self.to) > 0 && self.to != filter.to {
   110  		return false
   111  	}
   112  	if len(self.from) > 0 && self.from != filter.from {
   113  		return false
   114  	}
   115  	// Check the topic filtering
   116  	topics := make([]Topic, len(filter.matcher.conditions))
   117  	for i, group := range filter.matcher.conditions {
   118  		// Message should contain a single topic entry, extract
   119  		for topics[i] = range group {
   120  			break
   121  		}
   122  	}
   123  	return self.matcher.Matches(topics)
   124  }
   125  
   126  // Trigger is called when a filter successfully matches an inbound message.
   127  func (self filterer) Trigger(data interface{}) {
   128  	self.fn(data)
   129  }