Implement translib backend logic for the gNSI Authz feature

This commit adds the necessary transformer code to read authorization policy
counters and related state from the Redis databases.

Author: kanchanavelusamy

translib/log/level.go

@@ -0,0 +1,10 @@
+package log
+
+import "github.com/golang/glog"
+
+const (
+	ERROR glog.Level = iota
+	WARNING
+	INFO
+	DEBUG
+)

translib/tlerr/tlerr.go

@@ -31,7 +31,10 @@ package tlerr
 
 import (
 	//	"fmt"
+	"errors"
 	"github.com/Azure/sonic-mgmt-common/cvl"
+	lvl "github.com/Azure/sonic-mgmt-common/translib/log"
+	"github.com/golang/glog"
 	"golang.org/x/text/language"
 	"golang.org/x/text/message"
 	//	"errors"
@@ -190,3 +193,32 @@ type TranslibBusy struct {
 func (e TranslibBusy) Error() string {
 	return p.Sprintf("Translib Busy")
 }
+
+func IsTranslibRedisClientEntryNotExist(err error) bool {
+	switch err.(type) {
+	case *TranslibRedisClientEntryNotExist, TranslibRedisClientEntryNotExist:
+		return true
+	}
+	return false
+}
+
+// isDBEntryNotExistError returns `true` if `err` is (or wraps around) an error
+// of type `TranslibRedisClientEntryNotExist`.
+func isDBEntryNotExistError(err error) bool {
+	if IsTranslibRedisClientEntryNotExist(err) {
+		return true
+	}
+	pdberr := &TranslibRedisClientEntryNotExist{}
+	return errors.As(err, &TranslibRedisClientEntryNotExist{}) || errors.As(err, &pdberr)
+}
+
+// ErrorSeverity based on `err` calculates the VLOG level.
+func ErrorSeverity(err error) glog.Level {
+	if err == nil {
+		return lvl.DEBUG
+	}
+	if isDBEntryNotExistError(err) {
+		return lvl.DEBUG
+	}
+	return lvl.ERROR
+}

translib/transformer/subscribe_req_xlate.go

@@ -44,6 +44,7 @@ type subscribeReqXlator struct {
 type subscribeReq struct {
 	reqLogId         string
 	reqUri           string
+	requestURI       string
 	ygPath           string
 	isTrgtPathWldcrd bool
 	gPath            *gnmipb.Path
@@ -478,7 +479,7 @@ func (pathXltr *subscribePathXlator) handleSubtreeNodeXlate() error {
 		log.Info(pathXltr.subReq.reqLogId, "handleSubtreeNodeXlate: handleSubtreeNodeXlate: uriSubtree: ", uriSubtree)
 	}
 
-	subInParam := XfmrSubscInParams{uriSubtree, pathXltr.subReq.dbs, make(RedisDbMap), TRANSLATE_SUBSCRIBE}
+	subInParam := XfmrSubscInParams{uri: uriSubtree, requestURI: pathXltr.subReq.requestURI, dbs: pathXltr.subReq.dbs, dbDataMap: make(RedisDbMap), subscProc: TRANSLATE_SUBSCRIBE}
 	subOutPram, subErr := xfmrSubscSubtreeHandler(subInParam, ygXpathInfo.xfmrFunc)
 
 	if log.V(dbLgLvl) {

translib/transformer/xfmr_interface.go

@@ -76,10 +76,11 @@ type notificationOpts struct {
 
 // XfmrSubscInParams represents input to subscribe subtree callbacks - request uri, DBs info access-pointers, DB info for request uri and subscription process type from translib.
 type XfmrSubscInParams struct {
-	uri       string
-	dbs       [db.MaxDB]*db.DB
-	dbDataMap RedisDbMap
-	subscProc SubscProcType
+	uri        string
+	requestURI string
+	dbs        [db.MaxDB]*db.DB
+	dbDataMap  RedisDbMap
+	subscProc  SubscProcType
 }
 
 // XfmrSubscOutParams represents output from subscribe subtree callback - DB data for request uri, Need cache, OnChange, subscription preference and interval.