Initial commit on Forgejo

Fresh repository history for elektrine/elektrine-haraka hosted at
https://git.elektrine.com/elektrine/elektrine-haraka.

lib/text-normalizer.js

@@ -0,0 +1,73 @@
+/**
+ * Header text normalization helpers.
+ *
+ * Fixes common mojibake where UTF-8 bytes were interpreted as Latin-1.
+ */
+
+'use strict';
+
+function count_replacement_chars(value) {
+    if (typeof value !== 'string' || value.length === 0) return 0;
+    return (value.match(/\uFFFD/g) || []).length;
+}
+
+function has_c1_controls(value) {
+    return /[\u0080-\u009F]/.test(value);
+}
+
+function count_mojibake_utf8_latin1_pairs(value) {
+    let count = 0;
+    for (let i = 0; i < value.length - 1; i += 1) {
+        const a = value.charCodeAt(i);
+        const b = value.charCodeAt(i + 1);
+        // Pattern of UTF-8 byte sequences misread as Latin-1 code points.
+        if (a >= 0x00C2 && a <= 0x00F4 && b >= 0x0080 && b <= 0x00BF) {
+            count += 1;
+        }
+    }
+    return count;
+}
+
+function try_repair_utf8_latin1_mojibake(value) {
+    if (typeof value !== 'string' || value.length === 0) return value;
+
+    const cps = Array.from(value, (char) => char.codePointAt(0));
+    if (cps.some((cp) => cp > 0xFF)) {
+        return value;
+    }
+
+    const repaired = Buffer.from(cps).toString('utf8');
+    if (!repaired) return value;
+
+    const before_controls = has_c1_controls(value);
+    const after_controls = has_c1_controls(repaired);
+    const before_pairs = count_mojibake_utf8_latin1_pairs(value);
+    const after_pairs = count_mojibake_utf8_latin1_pairs(repaired);
+    const replacement_count = count_replacement_chars(repaired);
+
+    if (before_controls && !after_controls) {
+        if (replacement_count === 0) return repaired;
+
+        // Allow partial recovery when controls disappear and mojibake pairs drop sharply.
+        // This handles cases where one continuation byte was dropped upstream.
+        if (before_pairs >= 3 && after_pairs < before_pairs && replacement_count <= 2) {
+            return repaired;
+        }
+    }
+
+    if (before_pairs > 0 && after_pairs < before_pairs && replacement_count === 0) {
+        return repaired;
+    }
+
+    return value;
+}
+
+function normalize_header(value) {
+    if (typeof value !== 'string') return value;
+    return try_repair_utf8_latin1_mojibake(value);
+}
+
+module.exports = {
+    normalize_header,
+    try_repair_utf8_latin1_mojibake
+};