github.com/myafeier/fabric@v1.0.1-0.20170722181825-3a4b1f2bce86/orderer/common/filter/filter.go (about) 1 /* 2 Copyright IBM Corp. 2016 All Rights Reserved. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package filter 18 19 import ( 20 "fmt" 21 22 ab "github.com/hyperledger/fabric/protos/common" 23 ) 24 25 // Action is used to express the output of a rule 26 type Action int 27 28 const ( 29 // Accept indicates that the message should be processed 30 Accept = iota 31 // Reject indicates that the message should not be processed 32 Reject 33 // Forward indicates that the rule could not determine the correct course of action 34 Forward 35 ) 36 37 // Rule defines a filter function which accepts, rejects, or forwards (to the next rule) an Envelope 38 type Rule interface { 39 // Apply applies the rule to the given Envelope, replying with the Action to take for the message 40 // If the filter Accepts a message, it should provide a committer to use when writing the message to the chain 41 Apply(message *ab.Envelope) (Action, Committer) 42 } 43 44 // Committer is returned by postfiltering and should be invoked once the message has been written to the blockchain 45 type Committer interface { 46 // Commit performs whatever action should be performed upon committing of a message 47 Commit() 48 49 // Isolated returns whether this transaction should have a block to itself or may be mixed with other transactions 50 Isolated() bool 51 } 52 53 type noopCommitter struct{} 54 55 func (nc noopCommitter) Commit() {} 56 func (nc noopCommitter) Isolated() bool { return false } 57 58 // NoopCommitter does nothing on commit and is not isolated 59 var NoopCommitter = Committer(noopCommitter{}) 60 61 // EmptyRejectRule rejects empty messages 62 var EmptyRejectRule = Rule(emptyRejectRule{}) 63 64 type emptyRejectRule struct{} 65 66 func (a emptyRejectRule) Apply(message *ab.Envelope) (Action, Committer) { 67 if message.Payload == nil { 68 return Reject, nil 69 } 70 return Forward, nil 71 } 72 73 // AcceptRule always returns Accept as a result for Apply 74 var AcceptRule = Rule(acceptRule{}) 75 76 type acceptRule struct{} 77 78 func (a acceptRule) Apply(message *ab.Envelope) (Action, Committer) { 79 return Accept, NoopCommitter 80 } 81 82 // RuleSet is used to apply a collection of rules 83 type RuleSet struct { 84 rules []Rule 85 } 86 87 // NewRuleSet creates a new RuleSet with the given ordered list of Rules 88 func NewRuleSet(rules []Rule) *RuleSet { 89 return &RuleSet{ 90 rules: rules, 91 } 92 } 93 94 // Apply applies the rules given for this set in order, returning the committer, nil on valid, or nil, err on invalid 95 func (rs *RuleSet) Apply(message *ab.Envelope) (Committer, error) { 96 for _, rule := range rs.rules { 97 action, committer := rule.Apply(message) 98 switch action { 99 case Accept: 100 return committer, nil 101 case Reject: 102 return nil, fmt.Errorf("Rejected by rule: %T", rule) 103 default: 104 } 105 } 106 return nil, fmt.Errorf("No matching filter found") 107 }