[FAB-9834] interfaces for key-level validation

This change set introduces new interfaces used for validation of transactions
that use key-level endorsements.

Change-Id: I496e4e329bf1613f816d6a2c537da58fcb60124b
Signed-off-by: Alessandro Sorniotti <ale.linux@sopit.net>
Signed-off-by: Matthias Neugschwandtner <eug@zurich.ibm.com>

core/common/validation/statebased/validator.go

@@ -0,0 +1,39 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package statebased
+
+import (
+	"github.com/hyperledger/fabric/protos/peer"
+)
+
+// StateBasedValidator is used to validate a transaction that performs changes to
+// KVS keys that use key-level endorsement policies. This interface is supposed to be called
+// by any validator plugin (including the default validator plugin). The functions of this
+// interface are to be called as follows:
+// 1) the validator plugin extracts the read-write set from the transaction and calls PreValidate
+//    (even before determining whether the transaction is valid)
+// 2) the validator plugin calls Validate before or after having determined the validity of the
+//    transaction based on other considerations
+// 3) the validator plugin determines the overall validity of the transaction and then calls
+//    PostValidate
+type StateBasedValidator interface {
+	// PreValidate sets the internal data structures of the validator needed before validation
+	// of `rwset` on the specified channel at the specified height
+	PreValidate(ch, cc string, blockNum, txNum uint64, rwset []byte) error
+	// TODO: remove the channel argument as part of FAB-9908
+
+	// Validate determines whether the transaction on the specified channel at the specified height
+	// is valid according to its chaincode-level endorsement policy and any key-level validation
+	// parametres
+	Validate(ch, cc string, blockNum, txNum uint64, rwset, prp, ep []byte, endorsements []*peer.Endorsement) error
+	// TODO: remove the channel argument as part of FAB-9908
+
+	// PostValidate sets the internal data structures of the validator needed after the validation
+	// code was determined for a transaction on the specified channel at the specified height
+	PostValidate(ch, cc string, blockNum, txNum uint64, vc peer.TxValidationCode) error
+	// TODO: remove the channel argument as part of FAB-9908
+}