[FAB-9505] Export Gate and Role values used in policies

This changeset groups and exports the gate and role values that can be
used when constructing strings corresponding to policies.

It also removes references to the "orderer" role value as this is not
supported - see `MSPRoleType` values in `msp_principal.proto`.

Change-Id: Ic8df3bc38721abe80df25038068908650fae9084
Signed-off-by: Kostas Christidis <kostas@christidis.io>

common/cauthdsl/policyparser.go

@@ -21,15 +21,37 @@ import (
 	"reflect"
 	"regexp"
 	"strconv"
+	"strings"
 
 	"github.com/Knetic/govaluate"
 	"github.com/hyperledger/fabric/protos/common"
 	"github.com/hyperledger/fabric/protos/msp"
 	"github.com/hyperledger/fabric/protos/utils"
 )
 
-var regex *regexp.Regexp = regexp.MustCompile("^([[:alnum:].-]+)([.])(member|admin|client|peer|orderer)$")
-var regexErr *regexp.Regexp = regexp.MustCompile("^No parameter '([^']+)' found[.]$")
+// Gate values
+const (
+	GateAnd   = "And"
+	GateOr    = "Or"
+	GateOutOf = "OutOf"
+)
+
+// Role values for principals
+const (
+	RoleAdmin  = "admin"
+	RoleMember = "member"
+	RoleClient = "client"
+	RolePeer   = "peer"
+	// RoleOrderer = "orderer" TODO
+)
+
+var (
+	regex = regexp.MustCompile(
+		fmt.Sprintf("^([[:alnum:].-]+)([.])(%s|%s|%s|%s)$",
+			RoleAdmin, RoleMember, RoleClient, RolePeer),
+	)
+	regexErr = regexp.MustCompile("^No parameter '([^']+)' found[.]$")
+)
 
 // a stub function - it returns the same string as it's passed.
 // This will be evaluated by second/third passes to convert to a proto policy
@@ -150,13 +172,13 @@ func secondPass(args ...interface{}) (interface{}, error) {
 			/* get the right role */
 			var r msp.MSPRole_MSPRoleType
 			switch subm[0][3] {
-			case "member":
+			case RoleMember:
 				r = msp.MSPRole_MEMBER
-			case "admin":
+			case RoleAdmin:
 				r = msp.MSPRole_ADMIN
-			case "client":
+			case RoleClient:
 				r = msp.MSPRole_CLIENT
-			case "peer":
+			case RolePeer:
 				r = msp.MSPRole_PEER
 			default:
 				return nil, fmt.Errorf("Error parsing role %s", t)
@@ -203,24 +225,37 @@ func newContext() *context {
 
 // FromString takes a string representation of the policy,
 // parses it and returns a SignaturePolicyEnvelope that
-// implements that policy. The supported language is as follows
+// implements that policy. The supported language is as follows:
 //
 // GATE(P[, P])
 //
-// where
+// where:
 //	- GATE is either "and" or "or"
 //	- P is either a principal or another nested call to GATE
 //
-// a principal is defined as
+// A principal is defined as:
 //
 // ORG.ROLE
 //
-// where
+// where:
 //	- ORG is a string (representing the MSP identifier)
-//	- ROLE is either the string "member", "admin", "client", "peer", or the string "orderer" representing the required role
+//	- ROLE takes the value of any of the RoleXXX constants representing
+//    the required role
 func FromString(policy string) (*common.SignaturePolicyEnvelope, error) {
 	// first we translate the and/or business into outof gates
-	intermediate, err := govaluate.NewEvaluableExpressionWithFunctions(policy, map[string]govaluate.ExpressionFunction{"AND": and, "and": and, "OR": or, "or": or, "OUTOF": outof, "outof": outof, "OutOf": outof})
+	intermediate, err := govaluate.NewEvaluableExpressionWithFunctions(
+		policy, map[string]govaluate.ExpressionFunction{
+			GateAnd:                  and,
+			strings.ToLower(GateAnd): and,
+			strings.ToUpper(GateAnd): and,
+			GateOr:                     or,
+			strings.ToLower(GateOr):    or,
+			strings.ToUpper(GateOr):    or,
+			GateOutOf:                  outof,
+			strings.ToLower(GateOutOf): outof,
+			strings.ToUpper(GateOutOf): outof,
+		},
+	)
 	if err != nil {
 		return nil, err
 	}