Make our Webpack config compatible with Node 18+

Node 18 and newer switched to OpenSSL 3, which does not support the MD4
hash algorithm.

Unfortunately, Webpack 4 hardcodes the use of MD4 at various places.
This leaves us no other option than to monkey-patch node to transform
calls to the MD4 hash to use SHA256.

References:
https://github.com/webpack/webpack/issues/14532
69691525 (69691525)
Signed-off-by: David Mehren <git@herrmehren.de>

package.json

@@ -107,7 +107,7 @@
     "xss": "^1.0.3"
   },
   "engines": {
-    "node": "16.x"
+    "node": ">=16"
   },
   "bugs": "https://github.com/hedgedoc/hedgedoc/issues",
   "keywords": [

webpack.common.js

@@ -5,6 +5,13 @@ const CopyWebpackPlugin = require('copy-webpack-plugin')
 const MiniCssExtractPlugin = require('mini-css-extract-plugin')
 const { CleanWebpackPlugin } = require('clean-webpack-plugin')
 
+// This monkey-patches node to use sha256 instead of md4 for crypto.createHash
+// md4 is not available in node 18+ anymore, as that uses modern OpenSSL versions
+// Inspired by https://stackoverflow.com/questions/69394632/webpack-build-failing-with-err-ossl-evp-unsupported/69691525#69691525
+const crypto = require('crypto')
+const cryptoOrigCreateHash = crypto.createHash
+crypto.createHash = algorithm => cryptoOrigCreateHash(algorithm === 'md4' ? 'sha256' : algorithm)
+
 // Fix possible nofile-issues
 const fs = require('fs')
 const gracefulFs = require('graceful-fs')