Fill ARGS_POST variable even if body bytes were invalid JSON when JSON body processor is running

internal/bodyprocessors/json.go

@@ -30,12 +30,13 @@ func (js *jsonBodyProcessor) ProcessRequest(reader io.Reader, v plugintypes.Tran
 	// Process with recursion limit
 	col := v.ArgsPost()
 	data, err := readJSON(ss, bpo.RequestBodyRecursionLimit)
-	if err != nil {
-		return err
-	}
+	// The collection is populated before checking the error to still perform a best effort inspection of the payload
 	for key, value := range data {
 		col.SetIndex(key, 0, value)
 	}
+	if err != nil {
+		return err
+	}
 
 	// Store the raw JSON in the TX variable for validateSchema
 	// This is needed because RequestBody is a Single interface without a Set method
@@ -59,12 +60,13 @@ func (js *jsonBodyProcessor) ProcessResponse(reader io.Reader, v plugintypes.Tra
 	// Process with no recursion limit as we don't have a directive for response body
 	col := v.ResponseArgs()
 	data, err := readJSON(ss, ignoreJSONRecursionLimit)
-	if err != nil {
-		return err
-	}
+	// The collection is populated before checking the error to still perform a best effort inspection of the payload
 	for key, value := range data {
 		col.SetIndex(key, 0, value)
 	}
+	if err != nil {
+		return err
+	}
 
 	// Store the raw JSON in the TX variable for validateSchema
 	// This is needed because ResponseBody is a Single interface without a Set method
@@ -80,12 +82,15 @@ func readJSON(s string, maxRecursion int) (map[string]string, error) {
 	res := make(map[string]string)
 	key := []byte("json")
 
+	json := gjson.Parse(s)
+	err := readItems(json, key, maxRecursion, res)
+	if err != nil {
+		return res, err
+	}
 	if !gjson.Valid(s) {
 		return res, errors.New("invalid JSON")
 	}
-	json := gjson.Parse(s)
-	err := readItems(json, key, maxRecursion, res)
-	return res, err
+	return res, nil
 }
 
 // Transform JSON to a map[string]string

testing/engine/json.go

@@ -74,3 +74,89 @@ SecRule ARGS:json.test3 "@eq 3" "id: 1010, phase:2, log, block"
 SecRule RESPONSE_ARGS:json.test4 "@eq 3" "id: 1011, phase:4, log, block"
 `,
 })
+
+var _ = profile.RegisterProfile(profile.Profile{
+	Meta: profile.Meta{
+		Author:      "kabbohus",
+		Description: "Test if truncated JSON request/response body work",
+		Enabled:     true,
+		Name:        "truncatedjsonyaml",
+	},
+	Tests: []profile.Test{
+		{
+			Title: "json",
+			Stages: []profile.Stage{
+				{
+					Stage: profile.SubStage{
+						Input: profile.StageInput{
+							URI:    "/index.php?json.test=456",
+							Method: "POST",
+							Headers: map[string]string{
+								"content-type": "application/json",
+							},
+							Data: `{"test":123, "test2": 456, "test3": [22, 44, 55]}`,
+						},
+						Output: profile.ExpectedOutput{
+							TriggeredRules: []int{
+								100,
+								101,
+								1100,
+								1101,
+								1104,
+								1010,
+								1000,
+								1011,
+								1111,
+								1200,
+								1201,
+							},
+							NonTriggeredRules: []int{
+								103,
+								1102,
+								1103,
+								1202,
+								1203,
+							},
+							Headers: map[string]string{
+								"Content-Type": "application/json",
+							},
+							Data: `{"test": 123, "test2": 456, "test3": [22, 44, 55], "test4": 3}`,
+						},
+					},
+				},
+			},
+		},
+	},
+	Rules: `
+SecRequestBodyAccess On
+SecResponseBodyAccess On
+SecResponseBodyMimeType application/json
+SecRequestBodyLimitAction ProcessPartial
+SecRequestBodyLimit 40
+SecRule REQUEST_HEADERS:content-type "application/json" "id: 100, phase:1, pass, log, ctl:requestBodyProcessor=JSON"
+SecRule RESPONSE_HEADERS:content-type "application/json" "id:1000, phase:3, pass, log, ctl:responseBodyProcessor=JSON"
+SecRule REQBODY_PROCESSOR "JSON" "id: 101,phase:2,log,block"
+
+# This is commented out because we want to check if body processor can work with partial JSON
+SecRule REQBODY_ERROR "!@eq 0" "id:1111, phase:2, log, block"
+
+SecRule REQUEST_BODY "456" "id:103, phase:2, log"
+SecRule ARGS:json.test "@eq 123" "id:1100, phase:2, log, block"
+SecRule ARGS:json.test3.0 "@eq 22" "id:1101, phase:2, log, block"
+SecRule ARGS:json.test3.1 "@eq 44" "id:1102, phase:2, log, block"
+SecRule ARGS:json.test3.2 "@eq 55" "id:1103, phase:2, log, block"
+
+# Both GET and POST can be matched for the same key
+SecRule ARGS:json.test "@eq 456" "id:1104, phase:2, log, block"
+
+SecRule ARGS:json.test3 "@eq 1" "id: 1010, phase:2, log, block"
+
+# Check ARGS_POST
+SecRule ARGS_POST:json.test "@eq 123" "id:1200, phase:2, log, block"
+SecRule ARGS_POST:json.test3.0 "@eq 22" "id:1201, phase:2, log, block"
+SecRule ARGS_POST:json.test3.1 "@eq 44" "id:1202, phase:2, log, block"
+SecRule ARGS_POST:json.test3.2 "@eq 55" "id:1203, phase:2, log, block"
+
+SecRule RESPONSE_ARGS:json.test4 "@eq 3" "id: 1011, phase:4, log, block"
+`,
+})