From a578d216635b7c196de4ae54e9b10e7384c3952d Mon Sep 17 00:00:00 2001
From: C-3PO <c-3po@jedipedia.net>
Date: Fri, 22 Jun 2018 17:17:12 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=8E=A8=20Improve=20Bencode=20parser?=
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---
 src/ssn/bencodeParser.ts | 117 +++++++++++++++++++++------------------
 src/ssn/getSolidpkg.ts   |   4 +-
 2 files changed, 64 insertions(+), 57 deletions(-)

diff --git a/src/ssn/bencodeParser.ts b/src/ssn/bencodeParser.ts
index c3f5189..0ea91cf 100644
--- a/src/ssn/bencodeParser.ts
+++ b/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)
-          obj = [];
-          do {
-              //read key
-              const out1 = bpParse(dv, pos);
-              pos = out1.pos;
-              //read value
-              const out2 = bpParse(dv, pos);
-              pos = out2.pos;
-              obj[out1.obj] = out2.obj;
-          } while (dv.getUint8(pos) !== 0x65); //'e' - end
-          pos += 1;
-          break;
+    case 0x64: { //'d' - dictionary (key-value object)
+      obj = [];
+      do {
+        //read key
+        const out1 = bpParse(dv, pos);
+        pos = out1.pos;
+        //read value
+        const out2 = bpParse(dv, pos);
+        pos = out2.pos;
+        obj[out1.obj] = out2.obj;
+      } while (dv.getUint8(pos) !== 0x65); //'e' - end
+      pos += 1;
+      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 = [];
-          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;
+      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
+        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
-          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;
-          }
-          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.');
+      //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;
+}
diff --git a/src/ssn/getSolidpkg.ts b/src/ssn/getSolidpkg.ts
index 3604ba8..7bf080d 100644
--- a/src/ssn/getSolidpkg.ts
+++ b/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 });