replacing homoglyphs when checking for profanities

closes #3844

backend/src/constants/homoglyphs.ts

@@ -0,0 +1,42 @@
+const obj = {
+  a: ["\u0430", "\u00e0", "\u00e1", "\u1ea1", "\u0105"],
+  c: ["\u0441", "\u0188", "\u010b"],
+  d: ["\u0501", "\u0257"],
+  e: ["\u0435", "\u1eb9", "\u0117", "\u0117", "\u00e9", "\u00e8"],
+  g: ["\u0121"],
+  h: ["\u04bb"],
+  i: ["\u0456", "\u00ed", "\u00ec", "\u00ef"],
+  j: ["\u0458", "\u029d"],
+  k: ["\u03ba"],
+  l: ["\u04cf", "\u1e37"],
+  n: ["\u0578"],
+  o: [
+    "\u043e",
+    "\u03bf",
+    "\u0585",
+    "\u022f",
+    "\u1ecd",
+    "\u1ecf",
+    "\u01a1",
+    "\u00f6",
+    "\u00f3",
+    "\u00f2",
+  ],
+  p: ["\u0440"],
+  q: ["\u0566"],
+  s: ["\u0282"],
+  u: ["\u03c5", "\u057d", "\u00fc", "\u00fa", "\u00f9"],
+  v: ["\u03bd", "\u0475"],
+  x: ["\u0445", "\u04b3"],
+  y: ["\u0443", "\u00fd"],
+  z: ["\u0290", "\u017c"],
+};
+
+export function replaceHomoglyphs(str: string): string {
+  for (const key in obj) {
+    obj[key].forEach((value) => {
+      str = str.replace(value, key);
+    });
+  }
+  return str;
+}

backend/src/utils/validation.ts

@@ -1,4 +1,5 @@
 import _ from "lodash";
+import { replaceHomoglyphs } from "../constants/homoglyphs";
 import { profanities, regexProfanities } from "../constants/profanities";
 import { matchesAPattern, sanitizeString } from "./misc";
 
@@ -35,7 +36,7 @@ export function containsProfanity(text: string): boolean {
     .toLowerCase()
     .split(/[.,"/#!?$%^&*;:{}=\-_`~()\s\n]+/g)
     .map((str) => {
-      return sanitizeString(str) ?? "";
+      return replaceHomoglyphs(sanitizeString(str) ?? "");
     });
 
   const hasProfanity = regexProfanities.some((profanity) => {