🚧 Improve .solidpkg reader

src/ssn/getSolidpkg.ts

@@ -1,6 +1,6 @@
-import getUrlContents from './getUrlContents';
-import { Product } from './interfaces/ISettings';
-import verifyProductName from './verifyProductName';
+import getUrlContents from '../getUrlContents';
+import { Product } from '../interfaces/ISettings';
+import verifyProductName from '../verifyProductName';
 
 export default function getSolidpkg(product: Product, from: number, to: number): Promise<Buffer> {
   //Verify function arguments

src/ssn/modifyPassword.ts

@@ -0,0 +1,23 @@
+/** Takes a password as it is included in the extra field, and returns a password that can be used to decode the file. */
+export default function modifyPassword(passwordIn: Uint8Array) {
+  const passwordLength = passwordIn.byteLength;
+  const passwordOut = new Uint8Array(passwordLength);
+
+  for (let i = 0; i < passwordLength; i += 1) {
+    if (passwordIn[i] === 0) { break; }
+    let curChar = passwordIn[i] + (1 << (i % 32));
+    if (curChar > 0x7E) {
+      if (curChar === 0xFF || curChar === 0x7F) {
+        curChar = 0x3F;
+      } else {
+        curChar = curChar & 0x7F;
+      }
+    }
+    if (curChar < 0x21) {
+      curChar = (curChar | (1 << ((curChar % 3) + 5))) + 1;
+    }
+    passwordOut[i] = curChar;
+  }
+
+  return passwordOut;
+}

src/ssn/readSolidpkg.ts

@@ -1,9 +1,15 @@
+import { TextDecoder } from 'util';
+import modifyPassword from './modifyPassword';
+
 const MAGIC_END_OF_CENTRAL_DIR = 0x06054b50;
 const MAGIC_CENTRAL_DIR = 0x02014b50;
 const COMPRESSION_DEFLATE = 8;
 
+const Decoder = new TextDecoder('utf-8');
+
 export default function readSolidpkg(buffer: Buffer) {
-  const dv = new DataView(buffer.buffer);
+  const arrayBuffer = buffer.buffer;
+  const dv = new DataView(arrayBuffer);
 
   //--------------- READ END OF CENTRAL DIR ---------------
 
@@ -75,10 +81,37 @@ export default function readSolidpkg(buffer: Buffer) {
   const fileCommentLength = dv.getUint16(pos, true); pos += 2;
   pos += 8; //skip disk num start and file attributes
   const relOffset = dv.getUint32(pos, true); pos += 4;
-  pos += fileNameLength; //skip file name
-  //TODO: read password from extra field
+  const fileName = Decoder.decode(new DataView(arrayBuffer, pos, fileNameLength)); pos += fileNameLength; //skip file name
 
+  //read password from extra field
+  let encodedPassword: Uint8Array | undefined;
+  while (pos + 4 <= extraFieldLength) {
+    const fieldId = dv.getUint16(pos, true); pos += 2;
+    const fieldLength = dv.getUint16(pos, true); pos += 2;
+    switch (fieldId) {
+      case 0x8810: { //password
+        if (fieldLength > 120) {
+          throw new Error(`Password is too long, it should be 120 characters at most but is ${fieldLength} characters long.`);
+        }
+        const passwordLength = fieldLength;
+        encodedPassword = new Uint8Array(arrayBuffer, pos, fieldLength);
+        break;
+      }
+      case 0x80AE: //unknown, some kind of hash or checksum, ignore it
+        break;
+      default:
+        //unknown field, ignore it
+    }
+    pos += fieldLength;
+  }
+  if (typeof encodedPassword === 'undefined') {
+    throw new Error('Could not find password in extra field.');
+  }
+
+  const decodedPassword = modifyPassword(encodedPassword);
+
+  //TODO: read encrypted + compressed file
   //...
 
-  return { lastMod1, lastMod2, fileCrc, comprSize, uncomprSize, fileNameLength, extraFieldLength, fileCommentLength, relOffset };
+  return { lastMod1, lastMod2, fileCrc, comprSize, uncomprSize, fileNameLength, extraFieldLength, fileCommentLength, relOffset, fileName, encodedPassword, decodedPassword };
 }