diff --git a/pkg/exprhelpers/expr_lib.go b/pkg/exprhelpers/expr_lib.go
index db191b84a..b4f18a8a3 100644
--- a/pkg/exprhelpers/expr_lib.go
+++ b/pkg/exprhelpers/expr_lib.go
@@ -6,438 +6,438 @@ import (
 	"github.com/crowdsecurity/crowdsec/pkg/cticlient"
 )
 
-type exprCustomFunc struct {
-	name      string
-	function  func(params ...any) (any, error)
-	signature []interface{}
+type ExprCustomFunc struct {
+	Name      string
+	Function  func(params ...any) (any, error)
+	Signature []interface{}
 }
 
-var exprFuncs = []exprCustomFunc{
+var exprFuncs = []ExprCustomFunc{
 	{
-		name:     "CrowdsecCTI",
-		function: CrowdsecCTI,
-		signature: []interface{}{
+		Name:     "CrowdsecCTI",
+		Function: CrowdsecCTI,
+		Signature: []interface{}{
 			new(func(string) (*cticlient.SmokeItem, error)),
 		},
 	},
 	{
-		name:      "Flatten",
-		function:  Flatten,
-		signature: []interface{}{},
+		Name:      "Flatten",
+		Function:  Flatten,
+		Signature: []interface{}{},
 	},
 	{
-		name:      "Distinct",
-		function:  Distinct,
-		signature: []interface{}{},
+		Name:      "Distinct",
+		Function:  Distinct,
+		Signature: []interface{}{},
 	},
 	{
-		name:      "FlattenDistinct",
-		function:  FlattenDistinct,
-		signature: []interface{}{},
+		Name:      "FlattenDistinct",
+		Function:  FlattenDistinct,
+		Signature: []interface{}{},
 	},
 	{
-		name:     "Distance",
-		function: Distance,
-		signature: []interface{}{
+		Name:     "Distance",
+		Function: Distance,
+		Signature: []interface{}{
 			new(func(string, string, string, string) (float64, error)),
 		},
 	},
 	{
-		name:     "GetFromStash",
-		function: GetFromStash,
-		signature: []interface{}{
+		Name:     "GetFromStash",
+		Function: GetFromStash,
+		Signature: []interface{}{
 			new(func(string, string) (string, error)),
 		},
 	},
 	{
-		name:     "Atof",
-		function: Atof,
-		signature: []interface{}{
+		Name:     "Atof",
+		Function: Atof,
+		Signature: []interface{}{
 			new(func(string) float64),
 		},
 	},
 	{
-		name:     "JsonExtract",
-		function: JsonExtract,
-		signature: []interface{}{
+		Name:     "JsonExtract",
+		Function: JsonExtract,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "JsonExtractUnescape",
-		function: JsonExtractUnescape,
-		signature: []interface{}{
+		Name:     "JsonExtractUnescape",
+		Function: JsonExtractUnescape,
+		Signature: []interface{}{
 			new(func(string, ...string) string),
 		},
 	},
 	{
-		name:     "JsonExtractLib",
-		function: JsonExtractLib,
-		signature: []interface{}{
+		Name:     "JsonExtractLib",
+		Function: JsonExtractLib,
+		Signature: []interface{}{
 			new(func(string, ...string) string),
 		},
 	},
 	{
-		name:     "JsonExtractSlice",
-		function: JsonExtractSlice,
-		signature: []interface{}{
+		Name:     "JsonExtractSlice",
+		Function: JsonExtractSlice,
+		Signature: []interface{}{
 			new(func(string, string) []interface{}),
 		},
 	},
 	{
-		name:     "JsonExtractObject",
-		function: JsonExtractObject,
-		signature: []interface{}{
+		Name:     "JsonExtractObject",
+		Function: JsonExtractObject,
+		Signature: []interface{}{
 			new(func(string, string) map[string]interface{}),
 		},
 	},
 	{
-		name:     "ToJsonString",
-		function: ToJson,
-		signature: []interface{}{
+		Name:     "ToJsonString",
+		Function: ToJson,
+		Signature: []interface{}{
 			new(func(interface{}) string),
 		},
 	},
 	{
-		name:     "File",
-		function: File,
-		signature: []interface{}{
+		Name:     "File",
+		Function: File,
+		Signature: []interface{}{
 			new(func(string) []string),
 		},
 	},
 	{
-		name:     "RegexpInFile",
-		function: RegexpInFile,
-		signature: []interface{}{
+		Name:     "RegexpInFile",
+		Function: RegexpInFile,
+		Signature: []interface{}{
 			new(func(string, string) bool),
 		},
 	},
 	{
-		name:     "Upper",
-		function: Upper,
-		signature: []interface{}{
+		Name:     "Upper",
+		Function: Upper,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "Lower",
-		function: Lower,
-		signature: []interface{}{
+		Name:     "Lower",
+		Function: Lower,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "IpInRange",
-		function: IpInRange,
-		signature: []interface{}{
+		Name:     "IpInRange",
+		Function: IpInRange,
+		Signature: []interface{}{
 			new(func(string, string) bool),
 		},
 	},
 	{
-		name:     "TimeNow",
-		function: TimeNow,
-		signature: []interface{}{
+		Name:     "TimeNow",
+		Function: TimeNow,
+		Signature: []interface{}{
 			new(func() string),
 		},
 	},
 	{
-		name:     "ParseUri",
-		function: ParseUri,
-		signature: []interface{}{
+		Name:     "ParseUri",
+		Function: ParseUri,
+		Signature: []interface{}{
 			new(func(string) map[string][]string),
 		},
 	},
 	{
-		name:     "PathUnescape",
-		function: PathUnescape,
-		signature: []interface{}{
+		Name:     "PathUnescape",
+		Function: PathUnescape,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "QueryUnescape",
-		function: QueryUnescape,
-		signature: []interface{}{
+		Name:     "QueryUnescape",
+		Function: QueryUnescape,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "PathEscape",
-		function: PathEscape,
-		signature: []interface{}{
+		Name:     "PathEscape",
+		Function: PathEscape,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "QueryEscape",
-		function: QueryEscape,
-		signature: []interface{}{
+		Name:     "QueryEscape",
+		Function: QueryEscape,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "XMLGetAttributeValue",
-		function: XMLGetAttributeValue,
-		signature: []interface{}{
+		Name:     "XMLGetAttributeValue",
+		Function: XMLGetAttributeValue,
+		Signature: []interface{}{
 			new(func(string, string, string) string),
 		},
 	},
 	{
-		name:     "XMLGetNodeValue",
-		function: XMLGetNodeValue,
-		signature: []interface{}{
+		Name:     "XMLGetNodeValue",
+		Function: XMLGetNodeValue,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "IpToRange",
-		function: IpToRange,
-		signature: []interface{}{
+		Name:     "IpToRange",
+		Function: IpToRange,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "IsIPV6",
-		function: IsIPV6,
-		signature: []interface{}{
+		Name:     "IsIPV6",
+		Function: IsIPV6,
+		Signature: []interface{}{
 			new(func(string) bool),
 		},
 	},
 	{
-		name:     "IsIPV4",
-		function: IsIPV4,
-		signature: []interface{}{
+		Name:     "IsIPV4",
+		Function: IsIPV4,
+		Signature: []interface{}{
 			new(func(string) bool),
 		},
 	},
 	{
-		name:     "IsIP",
-		function: IsIP,
-		signature: []interface{}{
+		Name:     "IsIP",
+		Function: IsIP,
+		Signature: []interface{}{
 			new(func(string) bool),
 		},
 	},
 	{
-		name:     "LookupHost",
-		function: LookupHost,
-		signature: []interface{}{
+		Name:     "LookupHost",
+		Function: LookupHost,
+		Signature: []interface{}{
 			new(func(string) []string),
 		},
 	},
 	{
-		name:     "GetDecisionsCount",
-		function: GetDecisionsCount,
-		signature: []interface{}{
+		Name:     "GetDecisionsCount",
+		Function: GetDecisionsCount,
+		Signature: []interface{}{
 			new(func(string) int),
 		},
 	},
 	{
-		name:     "GetDecisionsSinceCount",
-		function: GetDecisionsSinceCount,
-		signature: []interface{}{
+		Name:     "GetDecisionsSinceCount",
+		Function: GetDecisionsSinceCount,
+		Signature: []interface{}{
 			new(func(string, string) int),
 		},
 	},
 	{
-		name:     "Sprintf",
-		function: Sprintf,
-		signature: []interface{}{
+		Name:     "Sprintf",
+		Function: Sprintf,
+		Signature: []interface{}{
 			new(func(string, ...interface{}) string),
 		},
 	},
 	{
-		name:     "ParseUnix",
-		function: ParseUnix,
-		signature: []interface{}{
+		Name:     "ParseUnix",
+		Function: ParseUnix,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "SetInStash", //FIXME: signature will probably blow everything up
-		function: SetInStash,
-		signature: []interface{}{
+		Name:     "SetInStash", //FIXME: signature will probably blow everything up
+		Function: SetInStash,
+		Signature: []interface{}{
 			new(func(string, string, string, *time.Duration) error),
 		},
 	},
 	{
-		name:     "Fields",
-		function: Fields,
-		signature: []interface{}{
+		Name:     "Fields",
+		Function: Fields,
+		Signature: []interface{}{
 			new(func(string) []string),
 		},
 	},
 	{
-		name:     "Index",
-		function: Index,
-		signature: []interface{}{
+		Name:     "Index",
+		Function: Index,
+		Signature: []interface{}{
 			new(func(string, string) int),
 		},
 	},
 	{
-		name:     "IndexAny",
-		function: IndexAny,
-		signature: []interface{}{
+		Name:     "IndexAny",
+		Function: IndexAny,
+		Signature: []interface{}{
 			new(func(string, string) int),
 		},
 	},
 	{
-		name:     "Join",
-		function: Join,
-		signature: []interface{}{
+		Name:     "Join",
+		Function: Join,
+		Signature: []interface{}{
 			new(func([]string, string) string),
 		},
 	},
 	{
-		name:     "Split",
-		function: Split,
-		signature: []interface{}{
+		Name:     "Split",
+		Function: Split,
+		Signature: []interface{}{
 			new(func(string, string) []string),
 		},
 	},
 	{
-		name:     "SplitAfter",
-		function: SplitAfter,
-		signature: []interface{}{
+		Name:     "SplitAfter",
+		Function: SplitAfter,
+		Signature: []interface{}{
 			new(func(string, string) []string),
 		},
 	},
 	{
-		name:     "SplitAfterN",
-		function: SplitAfterN,
-		signature: []interface{}{
+		Name:     "SplitAfterN",
+		Function: SplitAfterN,
+		Signature: []interface{}{
 			new(func(string, string, int) []string),
 		},
 	},
 	{
-		name:     "SplitN",
-		function: SplitN,
-		signature: []interface{}{
+		Name:     "SplitN",
+		Function: SplitN,
+		Signature: []interface{}{
 			new(func(string, string, int) []string),
 		},
 	},
 	{
-		name:     "Replace",
-		function: Replace,
-		signature: []interface{}{
+		Name:     "Replace",
+		Function: Replace,
+		Signature: []interface{}{
 			new(func(string, string, string, int) string),
 		},
 	},
 	{
-		name:     "ReplaceAll",
-		function: ReplaceAll,
-		signature: []interface{}{
+		Name:     "ReplaceAll",
+		Function: ReplaceAll,
+		Signature: []interface{}{
 			new(func(string, string, string) string),
 		},
 	},
 	{
-		name:     "Trim",
-		function: Trim,
-		signature: []interface{}{
+		Name:     "Trim",
+		Function: Trim,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "TrimLeft",
-		function: TrimLeft,
-		signature: []interface{}{
+		Name:     "TrimLeft",
+		Function: TrimLeft,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "TrimRight",
-		function: TrimRight,
-		signature: []interface{}{
+		Name:     "TrimRight",
+		Function: TrimRight,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "TrimSpace",
-		function: TrimSpace,
-		signature: []interface{}{
+		Name:     "TrimSpace",
+		Function: TrimSpace,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "TrimPrefix",
-		function: TrimPrefix,
-		signature: []interface{}{
+		Name:     "TrimPrefix",
+		Function: TrimPrefix,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "TrimSuffix",
-		function: TrimSuffix,
-		signature: []interface{}{
+		Name:     "TrimSuffix",
+		Function: TrimSuffix,
+		Signature: []interface{}{
 			new(func(string, string) string),
 		},
 	},
 	{
-		name:     "Get",
-		function: Get,
-		signature: []interface{}{
+		Name:     "Get",
+		Function: Get,
+		Signature: []interface{}{
 			new(func([]string, int) string),
 		},
 	},
 	{
-		name:     "ToString",
-		function: ToString,
-		signature: []interface{}{
+		Name:     "ToString",
+		Function: ToString,
+		Signature: []interface{}{
 			new(func(interface{}) string),
 		},
 	},
 	{
-		name:     "Match",
-		function: Match,
-		signature: []interface{}{
+		Name:     "Match",
+		Function: Match,
+		Signature: []interface{}{
 			new(func(string, string) bool),
 		},
 	},
 	{
-		name:     "KeyExists",
-		function: KeyExists,
-		signature: []interface{}{
+		Name:     "KeyExists",
+		Function: KeyExists,
+		Signature: []interface{}{
 			new(func(string, map[string]any) bool),
 		},
 	},
 	{
-		name:     "LogInfo",
-		function: LogInfo,
-		signature: []interface{}{
+		Name:     "LogInfo",
+		Function: LogInfo,
+		Signature: []interface{}{
 			new(func(string, ...interface{}) bool),
 		},
 	},
 	{
-		name:     "B64Decode",
-		function: B64Decode,
-		signature: []interface{}{
+		Name:     "B64Decode",
+		Function: B64Decode,
+		Signature: []interface{}{
 			new(func(string) string),
 		},
 	},
 	{
-		name:     "UnmarshalJSON",
-		function: UnmarshalJSON,
-		signature: []interface{}{
+		Name:     "UnmarshalJSON",
+		Function: UnmarshalJSON,
+		Signature: []interface{}{
 			new(func(string, map[string]interface{}, string) error),
 		},
 	},
 	{
-		name:     "ParseKV",
-		function: ParseKV,
-		signature: []interface{}{
+		Name:     "ParseKV",
+		Function: ParseKV,
+		Signature: []interface{}{
 			new(func(string, map[string]interface{}, string) error),
 		},
 	},
 	{
-		name:     "Hostname",
-		function: Hostname,
-		signature: []interface{}{
+		Name:     "Hostname",
+		Function: Hostname,
+		Signature: []interface{}{
 			new(func() (string, error)),
 		},
 	},
 	{
-		name:     "FloatApproxEqual",
-		function: FloatApproxEqual,
-		signature: []interface{}{
+		Name:     "FloatApproxEqual",
+		Function: FloatApproxEqual,
+		Signature: []interface{}{
 			new(func(float64, float64) bool),
 		},
 	},
diff --git a/pkg/exprhelpers/helpers.go b/pkg/exprhelpers/helpers.go
index 79a621c7d..350dd2974 100644
--- a/pkg/exprhelpers/helpers.go
+++ b/pkg/exprhelpers/helpers.go
@@ -60,9 +60,9 @@ func GetExprOptions(ctx map[string]interface{}) []expr.Option {
 		exprFunctionOptions = []expr.Option{}
 		for _, function := range exprFuncs {
 			exprFunctionOptions = append(exprFunctionOptions,
-				expr.Function(function.name,
-					function.function,
-					function.signature...,
+				expr.Function(function.Name,
+					function.Function,
+					function.Signature...,
 				))
 		}
 	}
diff --git a/pkg/waf/request.go b/pkg/waf/request.go
index 5e792a13b..6029adc3e 100644
--- a/pkg/waf/request.go
+++ b/pkg/waf/request.go
@@ -58,12 +58,12 @@ type ReqDumpFilter struct {
 	ArgsDrop           bool
 }
 
-func (r *ParsedRequest) DumpRequest(params ...any) *ReqDumpFilter {
+func (r *ParsedRequest) DumpRequest(params ...any) (any, error) {
 	filter := ReqDumpFilter{}
 	filter.BodyDrop = true
 	filter.HeadersNameFilters = []string{"cookie", "authorization"}
 	filter.req = r
-	return &filter
+	return &filter, nil
 }
 
 // clear filters
diff --git a/pkg/waf/request_test.go b/pkg/waf/request_test.go
index 2625e11f5..b4f50761c 100644
--- a/pkg/waf/request_test.go
+++ b/pkg/waf/request_test.go
@@ -161,7 +161,8 @@ func TestBodyDumper(t *testing.T) {
 	for idx, test := range tests {
 
 		t.Run(test.name, func(t *testing.T) {
-			orig_dr := test.req.DumpRequest()
+			tmp_dr, _ := test.req.DumpRequest()
+			orig_dr := tmp_dr.(*ReqDumpFilter)
 			result := test.filter(orig_dr).GetFilteredRequest()
 
 			if len(result.Body) != len(test.expect.Body) {
diff --git a/pkg/waf/waap.go b/pkg/waf/waap.go
index 2820bb8c4..497d4eef7 100644
--- a/pkg/waf/waap.go
+++ b/pkg/waf/waap.go
@@ -34,19 +34,26 @@ const (
 func (h *Hook) Build(hookStage int) error {
 
 	ctx := map[string]interface{}{}
+	opts := []expr.Option{}
 	switch hookStage {
 	case hookOnLoad:
-		ctx = GetOnLoadEnv(&WaapRuntimeConfig{})
+		opts = GetOnLoadEnv(ctx, &WaapRuntimeConfig{})
 	case hookPreEval:
-		ctx = GetPreEvalEnv(&WaapRuntimeConfig{}, &ParsedRequest{})
+		ctx["IsInBand"] = true
+		ctx["IsOutBand"] = true
+		opts = GetPreEvalEnv(ctx, &WaapRuntimeConfig{}, &ParsedRequest{})
 	case hookPostEval:
-		ctx = GetPostEvalEnv(&WaapRuntimeConfig{}, &ParsedRequest{})
+		ctx["IsInBand"] = true
+		ctx["IsOutBand"] = true
+		opts = GetPostEvalEnv(ctx, &WaapRuntimeConfig{}, &ParsedRequest{})
 	case hookOnMatch:
-		ctx = GetOnMatchEnv(&WaapRuntimeConfig{}, &ParsedRequest{}, types.Event{})
+		ctx["evt"] = types.Event{}
+		ctx["IsInBand"] = true
+		ctx["IsOutBand"] = true
+		opts = GetOnMatchEnv(ctx, &WaapRuntimeConfig{}, &ParsedRequest{})
 	}
-	opts := GetExprWAFOptions(ctx)
 	if h.Filter != "" {
-		program, err := expr.Compile(h.Filter, opts...) //FIXME: opts
+		program, err := expr.Compile(h.Filter, opts...)
 		if err != nil {
 			return fmt.Errorf("unable to compile filter %s : %w", h.Filter, err)
 		}
@@ -283,7 +290,7 @@ func (wc *WaapConfig) Build() (*WaapRuntimeConfig, error) {
 func (w *WaapRuntimeConfig) ProcessOnLoadRules() error {
 	for _, rule := range w.CompiledOnLoad {
 		if rule.FilterExpr != nil {
-			output, err := exprhelpers.Run(rule.FilterExpr, GetOnLoadEnv(w), w.Logger, w.Logger.Level >= log.DebugLevel)
+			output, err := exprhelpers.Run(rule.FilterExpr, map[string]interface{}{}, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				return fmt.Errorf("unable to run waap on_load filter %s : %w", rule.Filter, err)
 			}
@@ -299,7 +306,7 @@ func (w *WaapRuntimeConfig) ProcessOnLoadRules() error {
 			}
 		}
 		for _, applyExpr := range rule.ApplyExpr {
-			_, err := exprhelpers.Run(applyExpr, GetOnLoadEnv(w), w.Logger, w.Logger.Level >= log.DebugLevel)
+			_, err := exprhelpers.Run(applyExpr, map[string]interface{}{}, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				log.Errorf("unable to apply waap on_load expr: %s", err)
 				continue
@@ -310,10 +317,14 @@ func (w *WaapRuntimeConfig) ProcessOnLoadRules() error {
 }
 
 func (w *WaapRuntimeConfig) ProcessOnMatchRules(request *ParsedRequest, evt types.Event) error {
-
+	ctx := map[string]interface{}{
+		"evt":       evt,
+		"IsInBand":  request.IsInBand,
+		"IsOutBand": request.IsOutBand,
+	}
 	for _, rule := range w.CompiledOnMatch {
 		if rule.FilterExpr != nil {
-			output, err := exprhelpers.Run(rule.FilterExpr, GetOnMatchEnv(w, request, evt), w.Logger, w.Logger.Level >= log.DebugLevel)
+			output, err := exprhelpers.Run(rule.FilterExpr, ctx, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				return fmt.Errorf("unable to run waap on_match filter %s : %w", rule.Filter, err)
 			}
@@ -329,7 +340,7 @@ func (w *WaapRuntimeConfig) ProcessOnMatchRules(request *ParsedRequest, evt type
 			}
 		}
 		for _, applyExpr := range rule.ApplyExpr {
-			_, err := exprhelpers.Run(applyExpr, GetOnMatchEnv(w, request, evt), w.Logger, w.Logger.Level >= log.DebugLevel)
+			_, err := exprhelpers.Run(applyExpr, ctx, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				log.Errorf("unable to apply waap on_match expr: %s", err)
 				continue
@@ -340,9 +351,13 @@ func (w *WaapRuntimeConfig) ProcessOnMatchRules(request *ParsedRequest, evt type
 }
 
 func (w *WaapRuntimeConfig) ProcessPreEvalRules(request *ParsedRequest) error {
+	ctx := map[string]interface{}{
+		"IsInBand":  request.IsInBand,
+		"IsOutBand": request.IsOutBand,
+	}
 	for _, rule := range w.CompiledPreEval {
 		if rule.FilterExpr != nil {
-			output, err := exprhelpers.Run(rule.FilterExpr, GetPreEvalEnv(w, request), w.Logger, w.Logger.Level >= log.DebugLevel)
+			output, err := exprhelpers.Run(rule.FilterExpr, GetPreEvalEnv(ctx, w, request), w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				return fmt.Errorf("unable to run waap pre_eval filter %s : %w", rule.Filter, err)
 			}
@@ -359,7 +374,7 @@ func (w *WaapRuntimeConfig) ProcessPreEvalRules(request *ParsedRequest) error {
 		}
 		// here means there is no filter or the filter matched
 		for _, applyExpr := range rule.ApplyExpr {
-			_, err := exprhelpers.Run(applyExpr, GetPreEvalEnv(w, request), w.Logger, w.Logger.Level >= log.DebugLevel)
+			_, err := exprhelpers.Run(applyExpr, ctx, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				log.Errorf("unable to apply waap pre_eval expr: %s", err)
 				continue
@@ -371,9 +386,13 @@ func (w *WaapRuntimeConfig) ProcessPreEvalRules(request *ParsedRequest) error {
 }
 
 func (w *WaapRuntimeConfig) ProcessPostEvalRules(request *ParsedRequest) error {
+	ctx := map[string]interface{}{
+		"IsInBand":  request.IsInBand,
+		"IsOutBand": request.IsOutBand,
+	}
 	for _, rule := range w.CompiledPostEval {
 		if rule.FilterExpr != nil {
-			output, err := exprhelpers.Run(rule.FilterExpr, GetPostEvalEnv(w, request), w.Logger, w.Logger.Level >= log.DebugLevel)
+			output, err := exprhelpers.Run(rule.FilterExpr, ctx, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				return fmt.Errorf("unable to run waap post_eval filter %s : %w", rule.Filter, err)
 			}
@@ -390,7 +409,7 @@ func (w *WaapRuntimeConfig) ProcessPostEvalRules(request *ParsedRequest) error {
 		}
 		// here means there is no filter or the filter matched
 		for _, applyExpr := range rule.ApplyExpr {
-			_, err := exprhelpers.Run(applyExpr, GetPostEvalEnv(w, request), w.Logger, w.Logger.Level >= log.DebugLevel)
+			_, err := exprhelpers.Run(applyExpr, ctx, w.Logger, w.Logger.Level >= log.DebugLevel)
 			if err != nil {
 				log.Errorf("unable to apply waap post_eval expr: %s", err)
 				continue
@@ -551,6 +570,7 @@ func (w *WaapRuntimeConfig) SetActionByID(params ...any) (any, error) {
 
 // func (w *WaapRuntimeConfig) SetActionByID(name string, action string) error {
 func (w *WaapRuntimeConfig) SetActionByName(params ...any) (any, error) {
+	fmt.Printf("%v+\n", w)
 	if w.RemediationByTag == nil {
 		w.RemediationByTag = make(map[string]string)
 	}
diff --git a/pkg/waf/waf_expr_lib.go b/pkg/waf/waf_expr_lib.go
index 717b1bdff..b2a80723d 100644
--- a/pkg/waf/waf_expr_lib.go
+++ b/pkg/waf/waf_expr_lib.go
@@ -1,11 +1,3 @@
 package waf
 
 //This is a copy paste from expr_lib.go, we probably want to only have one ?
-
-type exprCustomFunc struct {
-	name      string
-	function  func(params ...any) (any, error)
-	signature []interface{}
-}
-
-var exprFuncs = []exprCustomFunc{}
diff --git a/pkg/waf/waf_helpers.go b/pkg/waf/waf_helpers.go
index ced1b68e7..aba4ec19b 100644
--- a/pkg/waf/waf_helpers.go
+++ b/pkg/waf/waf_helpers.go
@@ -3,40 +3,183 @@ package waf
 import (
 	"github.com/antonmedv/expr"
 	"github.com/crowdsecurity/crowdsec/pkg/exprhelpers"
-	"github.com/crowdsecurity/crowdsec/pkg/types"
 )
 
-func GetExprWAFOptions(ctx map[string]interface{}) []expr.Option {
+var exprOnLoadOptions = []expr.Option{}
+var exprPreEvalOptions = []expr.Option{}
+var exprPostEvalOptions = []expr.Option{}
+var exprOnMatchOptions = []expr.Option{}
+
+func GetOnLoadEnv(ctx map[string]interface{}, w *WaapRuntimeConfig) []expr.Option {
 	baseHelpers := exprhelpers.GetExprOptions(ctx)
-
-	for _, function := range exprFuncs {
-		baseHelpers = append(baseHelpers,
-			expr.Function(function.name,
-				function.function,
-				function.signature...,
-			))
+	onLoadHelpers := []exprhelpers.ExprCustomFunc{
+		{
+			Name:     "RemoveInBandRuleByID",
+			Function: w.DisableInBandRuleByID,
+			Signature: []interface{}{
+				new(func(int) error),
+			},
+		},
+		{
+			Name:     "RemoveInBandRuleByTag",
+			Function: w.DisableInBandRuleByTag,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "RemoveInBandRuleByName",
+			Function: w.DisableInBandRuleByName,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "RemoveOutBandRuleByID",
+			Function: w.DisableOutBandRuleByID,
+			Signature: []interface{}{
+				new(func(int) error),
+			},
+		},
+		{
+			Name:     "RemoveOutBandRuleByTag",
+			Function: w.DisableOutBandRuleByTag,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "RemoveOutBandRuleByName",
+			Function: w.DisableOutBandRuleByName,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "SetRemediationByTag",
+			Function: w.SetActionByTag,
+			Signature: []interface{}{
+				new(func(string, string) error),
+			},
+		},
+		{
+			Name:     "SetRemediationByID",
+			Function: w.SetActionByID,
+			Signature: []interface{}{
+				new(func(int, string) error),
+			},
+		},
+		{
+			Name:     "SetRemediationByName",
+			Function: w.SetActionByName,
+			Signature: []interface{}{
+				new(func(string, string) error),
+			},
+		},
 	}
-	return baseHelpers
+
+	if len(exprOnLoadOptions) == 0 {
+		for _, function := range onLoadHelpers {
+			exprOnLoadOptions = append(exprOnLoadOptions,
+				expr.Function(
+					function.Name,
+					function.Function,
+					function.Signature...,
+				),
+			)
+		}
+		exprOnLoadOptions = append(exprOnLoadOptions, baseHelpers...)
+	}
+
+	return exprOnLoadOptions
 }
 
-func GetOnLoadEnv(w *WaapRuntimeConfig) map[string]interface{} {
-	//FIXME: use expr.Function instead of this
-	return map[string]interface{}{
-		"RemoveInBandRuleByID":    w.DisableInBandRuleByID,
-		"RemoveInBandRuleByTag":   w.DisableInBandRuleByTag,
-		"RemoveInBandRuleByName":  w.DisableInBandRuleByName,
-		"RemoveOutBandRuleByID":   w.DisableOutBandRuleByID,
-		"RemoveOutBandRuleByTag":  w.DisableOutBandRuleByTag,
-		"RemoveOutBandRuleByName": w.DisableOutBandRuleByName,
-		"SetRemediationByTag":     w.SetActionByTag,
-		"SetRemediationByID":      w.SetActionByID,
-		"SetRemediationByName":    w.SetActionByName,
-	}
-}
+func GetPreEvalEnv(ctx map[string]interface{}, w *WaapRuntimeConfig, request *ParsedRequest) []expr.Option {
+
+	baseHelpers := exprhelpers.GetExprOptions(ctx)
+	preEvalHelpers := []exprhelpers.ExprCustomFunc{
+		{
+			Name:     "RemoveInBandRuleByID",
+			Function: w.RemoveInbandRuleByID,
+			Signature: []interface{}{
+				new(func(int) error),
+			},
+		},
+		{
+			Name:     "RemoveInBandRuleByTag",
+			Function: w.RemoveInbandRuleByTag,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "RemoveInBandRuleByName",
+			Function: w.RemoveInbandRuleByName,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "RemoveOutBandRuleByID",
+			Function: w.RemoveOutbandRuleByID,
+			Signature: []interface{}{
+				new(func(int) error),
+			},
+		},
+		{
+			Name:     "RemoveOutBandRuleByTag",
+			Function: w.RemoveOutbandRuleByTag,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "RemoveOutBandRuleByName",
+			Function: w.RemoveOutbandRuleByName,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "SetRemediationByTag",
+			Function: w.SetActionByTag,
+			Signature: []interface{}{
+				new(func(string, string) error),
+			},
+		},
+		{
+			Name:     "SetRemediationByID",
+			Function: w.SetActionByID,
+			Signature: []interface{}{
+				new(func(int, string) error),
+			},
+		},
+		{
+			Name:     "SetRemediationByName",
+			Function: w.SetActionByName,
+			Signature: []interface{}{
+				new(func(string, string) error),
+			},
+		},
+	}
+
+	if len(exprPreEvalOptions) == 0 {
+		for _, function := range preEvalHelpers {
+			exprPreEvalOptions = append(exprPreEvalOptions,
+				expr.Function(
+					function.Name,
+					function.Function,
+					function.Signature...,
+				),
+			)
+		}
+		exprPreEvalOptions = append(exprPreEvalOptions, baseHelpers...)
+	}
+
+	return exprPreEvalOptions
 
-func GetPreEvalEnv(w *WaapRuntimeConfig, request *ParsedRequest) map[string]interface{} {
 	//FIXME: use expr.Function instead of this
-	return map[string]interface{}{
+	/*return map[string]interface{}{
 		"IsInBand":                request.IsInBand,
 		"IsOutBand":               request.IsOutBand,
 		"RemoveInBandRuleByID":    w.RemoveInbandRuleByID,
@@ -48,20 +191,114 @@ func GetPreEvalEnv(w *WaapRuntimeConfig, request *ParsedRequest) map[string]inte
 		"SetRemediationByTag":     w.SetActionByTag,
 		"SetRemediationByID":      w.SetActionByID,
 		"SetRemediationByName":    w.SetActionByName,
-	}
+	}*/
 }
 
-func GetPostEvalEnv(w *WaapRuntimeConfig, request *ParsedRequest) map[string]interface{} {
-	//FIXME: use expr.Function instead of this
+func GetPostEvalEnv(ctx map[string]interface{}, w *WaapRuntimeConfig, request *ParsedRequest) []expr.Option {
+	baseHelpers := exprhelpers.GetExprOptions(ctx)
+	postEvalHelpers := []exprhelpers.ExprCustomFunc{
+		{
+			Name:     "DumpRequest",
+			Function: request.DumpRequest,
+			Signature: []interface{}{
+				new(func() *ReqDumpFilter),
+			},
+		},
+	}
+
+	if len(exprPostEvalOptions) == 0 {
+		for _, function := range postEvalHelpers {
+			exprPostEvalOptions = append(exprPostEvalOptions,
+				expr.Function(
+					function.Name,
+					function.Function,
+					function.Signature...,
+				),
+			)
+		}
+		exprPostEvalOptions = append(exprPostEvalOptions, baseHelpers...)
+	}
+
+	return exprPostEvalOptions
+
+	/*//FIXME: use expr.Function instead of this
 	return map[string]interface{}{
 		"IsInBand":    request.IsInBand,
 		"IsOutBand":   request.IsOutBand,
 		"DumpRequest": request.DumpRequest,
-	}
+	}*/
 }
 
-func GetOnMatchEnv(w *WaapRuntimeConfig, request *ParsedRequest, evt types.Event) map[string]interface{} {
-	//FIXME: use expr.Function instead of this
+func GetOnMatchEnv(ctx map[string]interface{}, w *WaapRuntimeConfig, request *ParsedRequest) []expr.Option {
+	baseHelpers := exprhelpers.GetExprOptions(ctx)
+	onMatchHelpers := []exprhelpers.ExprCustomFunc{
+		{
+			Name:     "SetRemediation",
+			Function: w.SetAction,
+			Signature: []interface{}{
+				new(func(string) error),
+			},
+		},
+		{
+			Name:     "SetReturnCode",
+			Function: w.SetHTTPCode,
+			Signature: []interface{}{
+				new(func(int) error),
+			},
+		},
+		{
+			Name:     "CancelEvent",
+			Function: w.CancelEvent,
+			Signature: []interface{}{
+				new(func() error),
+			},
+		},
+		{
+			Name:     "SendEvent",
+			Function: w.SendEvent,
+			Signature: []interface{}{
+				new(func() error),
+			},
+		},
+		{
+			Name:     "CancelAlert",
+			Function: w.CancelAlert,
+			Signature: []interface{}{
+				new(func() error),
+			},
+		},
+		{
+			Name:     "SendAlert",
+			Function: w.SendAlert,
+			Signature: []interface{}{
+				new(func() error),
+			},
+		},
+		{
+			Name:     "DumpRequest",
+			Function: request.DumpRequest,
+			Signature: []interface{}{
+				new(func() *ReqDumpFilter),
+			},
+		},
+	}
+
+	if len(exprOnMatchOptions) == 0 {
+		for _, function := range onMatchHelpers {
+			exprOnMatchOptions = append(exprOnMatchOptions,
+				expr.Function(
+					function.Name,
+					function.Function,
+					function.Signature...,
+				),
+			)
+		}
+		exprOnMatchOptions = append(exprOnMatchOptions, baseHelpers...)
+	}
+
+	return exprOnMatchOptions
+
+	/*//FIXME: use expr.Function instead of this
 	return map[string]interface{}{
 		"evt":            evt,
 		"req":            request,
@@ -74,5 +311,5 @@ func GetOnMatchEnv(w *WaapRuntimeConfig, request *ParsedRequest, evt types.Event
 		"CancelAlert":    w.CancelAlert,
 		"SendAlert":      w.SendAlert,
 		"DumpRequest":    request.DumpRequest,
-	}
+	}*/
 }