fix: validation of fractional numbers when using multipleOf schema

Author: mikuso

lib/validator.js

@@ -58,6 +58,24 @@ function createValidator(subprotocol, json) {
     const ajv = new Ajv({strictSchema: false});
     addFormats(ajv);
     ajv.addSchema(json);
+
+    ajv.removeKeyword("multipleOf");
+    ajv.addKeyword({
+        keyword: "multipleOf",
+        type: "number",
+        compile(schema) {
+            return data => {
+                const result = data / schema;
+                const epsilon = 1e-6; // small value to account for floating point precision errors
+                return Math.abs(Math.round(result) - result) < epsilon;
+            };
+        },
+        errors: false,
+        metaSchema: {
+            type: "number",
+        },
+    });
+
     return new Validator(subprotocol, ajv);
 }