[FAB-5317] Cleanup filters package cruft

The filters package has been changed significantly over the course of
development, and especially so with the recent removal of the committers
concept.  This has left a lot of cruft which actually makes the package
less usable and less testable.

This CR removes all that cruft, resulting in a significant decrease in
lines of code, while improving the quality of the tests.

Change-Id: I3dc131b5775bde3b198b6f33438a076041a38ed0
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

Author: Jason Yellick

orderer/common/deliver/deliver.go

@@ -21,7 +21,6 @@ import (
 
 	"github.com/hyperledger/fabric/common/policies"
 	"github.com/hyperledger/fabric/orderer/common/ledger"
-	"github.com/hyperledger/fabric/orderer/common/msgprocessor/filter"
 	"github.com/hyperledger/fabric/orderer/common/msgprocessor/sigfilter"
 	cb "github.com/hyperledger/fabric/protos/common"
 	ab "github.com/hyperledger/fabric/protos/orderer"
@@ -131,8 +130,8 @@ func (ds *deliverServer) deliverBlocks(srv ab.AtomicBroadcast_DeliverServer, env
 	lastConfigSequence := chain.Sequence()
 
 	sf := sigfilter.New(policies.ChannelReaders, chain.PolicyManager())
-	if sf.Apply(envelope) != filter.Forward {
-		logger.Warningf("[channel: %s] Received unauthorized deliver request", chdr.ChannelId)
+	if err := sf.Apply(envelope); err != nil {
+		logger.Warningf("[channel: %s] Received unauthorized deliver request: %s", chdr.ChannelId, err)
 		return sendStatusReply(srv, cb.Status_FORBIDDEN)
 	}
 
@@ -185,8 +184,8 @@ func (ds *deliverServer) deliverBlocks(srv ab.AtomicBroadcast_DeliverServer, env
 		if currentConfigSequence > lastConfigSequence {
 			lastConfigSequence = currentConfigSequence
 			sf := sigfilter.New(policies.ChannelReaders, chain.PolicyManager())
-			if sf.Apply(envelope) != filter.Forward {
-				logger.Warningf("[channel: %s] Client authorization revoked for deliver request", chdr.ChannelId)
+			if err := sf.Apply(envelope); err != nil {
+				logger.Warningf("[channel: %s] Client authorization revoked for deliver request: %s", chdr.ChannelId, err)
 				return sendStatusReply(srv, cb.Status_FORBIDDEN)
 			}
 		}

orderer/common/msgprocessor/configtxfilter/filter.go

@@ -1,64 +1,45 @@
 /*
-Copyright IBM Corp. 2016 All Rights Reserved.
+Copyright IBM Corp. All Rights Reserved.
 
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-                 http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
+SPDX-License-Identifier: Apache-2.0
 */
 
 package filter
 
 import (
-	"fmt"
+	"errors"
 
 	ab "github.com/hyperledger/fabric/protos/common"
 )
 
-// Action is used to express the output of a rule
-type Action int
-
-const (
-	// Accept indicates that the message should be processed
-	Accept = iota
-	// Reject indicates that the message should not be processed
-	Reject
-	// Forward indicates that the rule could not determine the correct course of action
-	Forward
-)
+// ErrEmptyMessage is returned by the empty message filter on rejection.
+var ErrEmptyMessage = errors.New("Message was empty")
 
 // Rule defines a filter function which accepts, rejects, or forwards (to the next rule) an Envelope
 type Rule interface {
-	// Apply applies the rule to the given Envelope, replying with the Action to take for the message
-	Apply(message *ab.Envelope) Action
+	// Apply applies the rule to the given Envelope, either successfully or returns error
+	Apply(message *ab.Envelope) error
 }
 
 // EmptyRejectRule rejects empty messages
 var EmptyRejectRule = Rule(emptyRejectRule{})
 
 type emptyRejectRule struct{}
 
-func (a emptyRejectRule) Apply(message *ab.Envelope) Action {
+func (a emptyRejectRule) Apply(message *ab.Envelope) error {
 	if message.Payload == nil {
-		return Reject
+		return ErrEmptyMessage
 	}
-	return Forward
+	return nil
 }
 
 // AcceptRule always returns Accept as a result for Apply
 var AcceptRule = Rule(acceptRule{})
 
 type acceptRule struct{}
 
-func (a acceptRule) Apply(message *ab.Envelope) Action {
-	return Accept
+func (a acceptRule) Apply(message *ab.Envelope) error {
+	return nil
 }
 
 // RuleSet is used to apply a collection of rules
@@ -76,14 +57,10 @@ func NewRuleSet(rules []Rule) *RuleSet {
 // Apply applies the rules given for this set in order, returning nil on valid or err on invalid
 func (rs *RuleSet) Apply(message *ab.Envelope) error {
 	for _, rule := range rs.rules {
-		action := rule.Apply(message)
-		switch action {
-		case Accept:
-			return nil
-		case Reject:
-			return fmt.Errorf("Rejected by rule: %T", rule)
-		default:
+		err := rule.Apply(message)
+		if err != nil {
+			return err
 		}
 	}
-	return fmt.Errorf("No matching filter found")
+	return nil
 }