🎨 Improve Bencode parser

src/ssn/bencodeParser.ts

@@ -7,67 +7,74 @@ import { TextDecoder } from 'util';
 const Decoder = new TextDecoder('utf-8');
 
 /** Takes a Bencoded-encoded file, parses it at the given starting position and returns a JSON object, or rejects on error. */
-export default function bpParse(dv: DataView, posIn: number = 0): { obj: any, pos: number } {
+function bpParse(dv: DataView, posIn: number = 0): { obj: any, pos: number } {
   let pos = posIn;
   let obj;
   const header = dv.getUint8(pos); pos += 1;
   switch (header) {
-      case 0x64: { //'d' - dictionary (key-value object)
+    case 0x64: { //'d' - dictionary (key-value object)
-          obj = [];
+      obj = [];
-          do {
+      do {
-              //read key
+        //read key
-              const out1 = bpParse(dv, pos);
+        const out1 = bpParse(dv, pos);
-              pos = out1.pos;
+        pos = out1.pos;
-              //read value
+        //read value
-              const out2 = bpParse(dv, pos);
+        const out2 = bpParse(dv, pos);
-              pos = out2.pos;
+        pos = out2.pos;
-              obj[out1.obj] = out2.obj;
+        obj[out1.obj] = out2.obj;
-          } while (dv.getUint8(pos) !== 0x65); //'e' - end
+      } while (dv.getUint8(pos) !== 0x65); //'e' - end
-          pos += 1;
+      pos += 1;
-          break;
+      break;
+    }
+    case 0x6C: { //'l' - list (array)
+      obj = [];
+      do {
+        //read entry
+        const out = bpParse(dv, pos);
+        pos = out.pos;
+        obj.push(out.obj);
+      } while (dv.getUint8(pos) !== 0x65); //'e' - end
+      pos += 1;
+      break;
+    }
+    case 0x69: { //'i' - integer
+      let curChar = dv.getUint8(pos); pos += 1;
+      let curNumber = 0;
+      while (curChar !== 0x65) { //'e' - end
+        if (curChar < 0x30 || curChar > 0x39) {
+          throw new Error('Unexpected int char during bencode parsing');
+        }
+        curNumber *= 10;
+        curNumber += curChar - 0x30;
+        curChar = dv.getUint8(pos); pos += 1;
       }
-      case 0x6C: { //'l' - list (array)
+      obj = curNumber;
-          obj = [];
+      break;
-          do {
+    }
-              //read entry
+    case 0x30: case 0x31: case 0x32: case 0x33: case 0x34:
-              const out = bpParse(dv, pos);
+    case 0x35: case 0x36: case 0x37: case 0x38: case 0x39: { //string prefixed by length
-              pos = out.pos;
+      //read string length
-              obj.push(out.obj);
+      let curChar: number = header;
-          } while (dv.getUint8(pos) !== 0x65); //'e' - end
+      let strLen = 0;
-          pos += 1;
+      while (curChar !== 0x3A) { //':' - integer delimiter, beginning of string
-          break;
+        if (curChar < 0x30 || curChar > 0x39) {
+          throw new Error('Unexpected string length during bencode parsing');
+        }
+        strLen *= 10;
+        strLen += curChar - 0x30;
+        curChar = dv.getUint8(pos); pos += 1;
       }
-      case 0x69: { //'i' - integer
+      //read string
-          let curChar = dv.getUint8(pos); pos += 1;
+      obj = Decoder.decode(new DataView(dv.buffer, pos, strLen));
-          let curNumber = 0;
+      pos += strLen;
-          while (curChar !== 0x65) { //'e' - end
+      break;
-              if (curChar < 0x30 || curChar > 0x39) {
+    }
-                  throw new Error('Unexpected int char during bencode parsing');
+    default:
-              }
+     throw new Error('Unexpected leading char during bencode parsing.');
-              curNumber *= 10;
-              curNumber += curChar - 0x30;
-              curChar = dv.getUint8(pos); pos += 1;
-          }
-          obj = curNumber;
-          break;
-      }
-      case 0x30: case 0x31: case 0x32: case 0x33: case 0x34:
-      case 0x35: case 0x36: case 0x37: case 0x38: case 0x39: { //string prefixed by length
-          //read string length
-          let curChar: number = header;
-          let strLen = 0;
-          while (curChar !== 0x3A) { //':' - integer delimiter, beginning of string
-              strLen *= 10;
-              strLen += curChar - 0x30;
-              curChar = dv.getUint8(pos); pos += 1;
-          }
-          //read string
-          obj = Decoder.decode(new DataView(dv.buffer, pos, strLen));
-          pos += strLen;
-          break;
-      }
-      default:
-          throw new Error('Unexpected leading char during bencode parsing.');
   }
   return { obj, pos };
 }
+
+export default function parseBencode(dv: DataView): any {
+  return bpParse(dv).obj;
+}

src/ssn/getSolidpkg.ts

@@ -2,7 +2,7 @@ import getUrlContents from '../getUrlContents';
 import { Product } from '../interfaces/ISettings';
 import ISolid from '../interfaces/ISolidFile';
 import verifyProductName from '../ssn/verifyProductName';
-import bpParse from './bencodeParser';
+import parseBencode from './bencodeParser';
 import extractFile from './extractFile';
 import readSsnFile from './readSsnFile';
 import verifySolidpkg from './verifySolidpkg';
@@ -39,7 +39,7 @@ export default async function getSolidpkg(product: Product, from: number, to: nu
 
   //Extract metafile.solid file
   const solidFile = await extractFile(firstFile, [new DataView(ssnFile)]);
-  const solidContents = bpParse(new DataView(solidFile)).obj as ISolid;
+  const solidContents = parseBencode(new DataView(solidFile)) as ISolid;
 
   //Verify metafile.solid for correctness
   verifySolidpkg(solidContents, { product, from, to });