From 12747394c0dc470627db39e8894cce0b2d8328b9 Mon Sep 17 00:00:00 2001
From: Martok <martok@martoks-place.de>
Date: Tue, 16 Jan 2024 19:49:23 +0100
Subject: [PATCH] fix: place injected scripts after the <meta charset> tag so
 it remains in the first 1k bytes

---
 lib/main.js | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/lib/main.js b/lib/main.js
index 49f49ba..d1df954 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -820,6 +820,27 @@ class PolyfillService {
         return newHeader;
     }
 
+    getScriptInsertPoint(data, lookForMeta = false) {
+        const pHead = data.indexOf("<head");
+        if (pHead < 0)
+            return false;
+        if (lookForMeta) {
+            // insert after charset tag if this is expected
+            const pCharset = data.indexOf("<meta charset=", pHead+5);
+            if (pCharset >= 0) {
+                const pPoint = data.indexOf(">", pCharset+16);
+                if (pPoint < 0)
+                    return false;
+                return pPoint + 1;
+            }
+        }
+        // just insert directly after head
+        const pPoint = data.indexOf(">", pHead+5);
+        if (pPoint < 0)
+            return false;
+        return pPoint + 1;
+    }
+
     modifyRequestData(data, activeFixes) {
         activeFixes.ensureCompiled();
         if (activeFixes.contentReplace) {
@@ -828,12 +849,10 @@ class PolyfillService {
             }
         }
         if (activeFixes.scripts) {
-            const p1 = data.indexOf("<head");
-            if (p1>=0) {
-                const p2 = data.indexOf(">", p1+5);
-                if (p2 >= 0) {
-                    data = data.slice(0, p2 + 1) + activeFixes.scripts + data.slice(p2 + 1);
-                }
+            const splicePos = this.getScriptInsertPoint(data.slice(0, 1024), true) ||
+                              this.getScriptInsertPoint(data);
+            if (splicePos >= 0) {
+                data = data.slice(0, splicePos) + activeFixes.scripts + data.slice(splicePos);
             }
         }
         return data;