WfcPatcher/Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace WfcPatcher {
	class Program {
		static void Main( string[] args ) {
			foreach ( string s in args ) {
				try {
					PatchFile( s );
				} catch ( Exception ex ) {
					Console.WriteLine( "Failed patching " + s );
					Console.WriteLine( ex.ToString() );
					Console.WriteLine();
				}
			}
		}

		static void PatchFile( string filename ) {
			Console.WriteLine( "Reading & Copying ROM..." );
			var ndsSrc = new System.IO.FileStream( filename, System.IO.FileMode.Open );
			var nds = new System.IO.FileStream( filename + ".wfc.nds", System.IO.FileMode.Create );
			Util.CopyStream( ndsSrc, nds, (int)ndsSrc.Length );

			// http://dsibrew.org/wiki/DSi_Cartridge_Header

			// overlays
			Console.WriteLine( "Patching Overlays..." );
			nds.Position = 0x50;
			uint arm9overlayoff = nds.ReadUInt32();
			uint arm9overlaylen = nds.ReadUInt32();
			uint arm7overlayoff = nds.ReadUInt32();
			uint arm7overlaylen = nds.ReadUInt32();

			PatchOverlay( nds, arm9overlayoff, arm9overlaylen );
			PatchOverlay( nds, arm7overlayoff, arm7overlaylen );
		}

		static void PatchOverlay( System.IO.FileStream nds, uint pos, uint len ) {
			// http://sourceforge.net/p/devkitpro/ndstool/ci/master/tree/source/ndsextract.cpp
			// http://sourceforge.net/p/devkitpro/ndstool/ci/master/tree/source/overlay.h

			nds.Position = 0x048;
			uint fatOffset = nds.ReadUInt32();

			for ( uint i = 0; i < len; i += 0x20 ) {
				nds.Position = pos + i;
				uint id = nds.ReadUInt32();
				uint ramAddr = nds.ReadUInt32();
				uint ramSize = nds.ReadUInt32();
				uint bssSize = nds.ReadUInt32();
				uint sinitInit = nds.ReadUInt32();
				uint sinitInitEnd = nds.ReadUInt32();
				uint fileId = nds.ReadUInt32();
				uint reserved = nds.ReadUInt32();

				nds.Position = fatOffset + 8 * id;
				uint overlayPositionStart = nds.ReadUInt32();
				uint overlayPositionEnd = nds.ReadUInt32();
				uint overlaySize = overlayPositionEnd - overlayPositionStart;

				nds.Position = overlayPositionStart;
				byte[] data = new byte[overlaySize];
				nds.Read( data, 0, (int)overlaySize );

				blz blz = new blz();
				byte[] decData = blz.BLZ_Decode( data );
				if ( ReplaceInData( decData ) ) {
					// if something was replaced, put it back into the ROM
					if ( blz.fileWasNotCompressed ) {
						data = decData; // which it should be anyway but yeah
					} else {
						data = blz.BLZ_Encode( decData, 0 );
					}
					nds.Position = overlayPositionStart;
					nds.Write( data, 0, data.Length );

					// and write proper offsets
					overlayPositionEnd = (uint)nds.Position;
					byte[] newPosEndData = BitConverter.GetBytes( overlayPositionEnd );
					nds.Position = fatOffset + 8 * id + 4;
					nds.Write( newPosEndData, 0, 4 );
				}

			}
		}

		static bool ReplaceInData( byte[] data ) {
			string search = "https://";
			string replace = "http://";
			byte[] searchBytes = Encoding.ASCII.GetBytes( search );
			byte[] replaceBytes = Encoding.ASCII.GetBytes( replace );
			int requiredPadding = searchBytes.Length + replaceBytes.Length;

			


			return true;
		}
	}
}