invoke String2Dword,addr PortString
                        mov HTTPPort,eax
                .else
                        mov al,byte ptr [edi]
                        mov byte ptr [esi],al
                        inc edi
                        inc esi
                        inc ecx
                .endif
        .endw
        .if ecx==URLLength      ; if there's no relative URL , we must add "/" to it.
                mov byte ptr [RelativeURL],"/"
        .endif
        ret
ParseURL endp
;==========================================================================
;                                GetFileName
;==========================================================================
; This function searches the url string for the last "/" character. If "/"
; is found, it's assumed that the file name follows "/" character.
;--------------------------------------------------------------------------
GetFileName proc URL:DWORD
        invoke RtlFillMemory,addr FileName,256,0
        invoke lstrlen,URL
        std               ; We will search for "/" in reverse direction
        mov edi,URL
        add edi,eax
        dec edi
        mov ecx,eax
        mov al,"/"
        repne scasb
        cld
        jne No_name
        cmp byte ptr [edi],"/"
        je  No_name
        inc edi
        inc edi
        invoke lstrcpy,addr FileName,edi
No_name:
        ret
GetFileName endp
;=====================================================================
;                               ShowProgress
;=====================================================================
; This procedure updates the progress bar and displays the number
; of bytes downloaded so far on the status bar
;=====================================================================
ShowProgress proc uses ebx edx hWnd:DWORD
        LOCAL temp[100]:BYTE
       .if ContentLength!=0
                xor edx,edx
                mov eax,CurrentDataSize
                mov ebx,1000
                mul ebx
                mov ebx,ContentLength
                div ebx
                invoke SendDlgItemMessage,hWnd,IDC_PROGRESS,PBM_SETPOS,eax,NULL
        .endif
        push CurrentDataSize
        push offset Downloading
        lea eax,temp
        push eax
        call wsprintfA
        add esp,12
        invoke SetStatusText,addr temp,NULL
        ret
ShowProgress endp
;====================================================================
;                               TranslateErrorCode
;====================================================================
; This function takes the error code and an address of a buffer and
; looks up the error string in the string resource.
;====================================================================
TranslateErrorCode proc ErrCode:DWORD, pErrString:DWORD
        invoke LoadString,hInstance,ErrCode,pErrString,512
        .if eax==0
                invoke LoadString,hInstance,1,pErrString,512
        .endif
        ret
TranslateErrorCode endp
;====================================================================
;                               GetErrorString
;====================================================================
; This function calls WSAGetLastError to retrieve the error code of 
; the last socket operation and looks up the error string in
; the string resource.
;====================================================================
GetErrorString proc pErrString:DWORD
        invoke WSAGetLastError
        push eax
        invoke TranslateErrorCode,eax,pErrString
        pop eax
        ret
GetErrorString endp
;====================================================================
;                               CloseSock
;====================================================================
; This function performs winsock library shutdown. It closes socket,
; output file, kills timer,and calls WSACleanup. It also clears the
; status bar and resets the progress bar control.
;====================================================================
CloseSock proc
        .if sock!=0
                invoke closesocket,sock
                mov sock,0
        .endif                
        .if FileHandle!=0
                invoke CloseHandle,FileHandle
        .endif
        .if TimerID!=0
                invoke KillTimer,hwnd,TimerID
                invoke ClearMessages,hwnd,WM_SOCKET
                invoke ClearMessages,hwndStatus,SB_SETTEXT
                invoke SendMessage,hwndStatus,SB_SETTEXT,1,NULL
        .endif
        invoke SendDlgItemMessage,hwnd,IDC_PROGRESS,PBM_SETPOS,0,0
        invoke SetWindowText,hwndStatus,NULL
        invoke SetDlgItemText,hwnd,IDC_NAME,NULL
        ret
CloseSock endp
SetStatusText PROC Text:DWORD, Text1:DWORD
        push Text1
        push Text
        push offset ErrorString
        call wsprintfA
        add esp,12
        invoke SetWindowText,hwndStatus,addr ErrorString
        ret
SetStatusText ENDP
EnableControls PROC
        invoke EnableWindow,hwndConnectButton,TRUE
        invoke EnableMenuItem,hMenu,IDM_CONNECT,MF_ENABLED
        ret 
EnableControls ENDP
DisableControls PROC
        invoke EnableWindow,hwndConnectButton,FALSE
        invoke EnableMenuItem,hMenu,IDM_CONNECT,MF_GRAYED
        ret
DisableControls ENDP
ConnectSocket PROC
        invoke DisableControls
        mov sock,0      ; We use the value of sock to check if the socket is closed so we must initialize it to 0
                                      ;  which means "closed or not created yet"
        invoke ParseURL,addr URLString  ; Parse the URL into host name, relative url and the http port
        invoke lstrlen,addr URLString
        .if eax>40
                invoke lstrcpyn,addr CommandString,addr URLString,20
                invoke lstrcat,addr CommandString,addr Dots
                invoke lstrlen,addr URLString
                sub eax,20
                push edi
                mov edi,offset URLString
                add edi,eax
                invoke lstrcat,addr CommandString,edi
                pop edi
        .else
                invoke lstrcpy,addr CommandString,addr URLString
        .endif        
        invoke SetDlgItemText,hwnd,IDC_NAME,\
                addr CommandString
        invoke socket,PF_INET,SOCK_STREAM,0     ; Create a stream socket
        .if eax!=INVALID_SOCKET
                mov sock,eax
                .if Resuming==FALSE
                        invoke SetStatusText,addr ResolvingServer,addr HostName
                        invoke inet_addr,addr HostName  ; Assume that the host name is not an ip address. If the host name is really an ip address,
                                                        ; the function will fail with eax==INADDR_NONE
                        .if eax==INADDR_NONE
                                invoke gethostbyname,addr HostName     ; Use this function to get the host ip address from host name.
                                .if eax==NULL
                                        invoke ShowErrorMessage
                                        ret
                                .endif
                                mov eax,[eax+12]
                                mov eax,[eax]
                                mov eax,[eax]
                                mov SocketAddress.sin_addr,eax
                        .else
                                mov SocketAddress.sin_addr,eax
                        .endif
                        mov SocketAddress.sin_family,AF_INET
                .endif
                invoke htons,HTTPPort   ; We must convert host byte order to network byte order
                mov SocketAddress.sin_port,ax
                invoke WSAAsyncSelect,sock,hwnd,WM_SOCKET,\     ; We choose to receive notification about successful connection,
                        FD_CONNECT or FD_READ or FD_CLOSE ; incoming data, and when the socket is closed
                .if eax==NULL
                        invoke SetStatusText,addr Connecting,addr HostName
                        invoke connect,sock,addr SocketAddress,sizeof SocketAddress     ; Make a connection with the remote host
                                                                        ; Since we operate in non-blocking mode, we wait for the window socket to call us when
                                                                        ; the events we are interested in occur.
                        .if eax==SOCKET_ERROR
                                invoke WSAGetLastError
                                .if eax!=WSAEWOULDBLOCK
                                        invoke ShowErrorMessage
                                .endif        
                        .endif
                .else
                        invoke ShowErrorMessage
                .endif
        .else
                invoke SetWindowText,hwndStatus,NULL
                invoke ShowErrorMessage
        .endif
        ret
ConnectSocket ENDP
ShowErrorMessage PROC
        invoke GetErrorString,addr ErrorString
        invoke MessageBox,hwnd,addr ErrorString,addr AppName,MB_OK+MB_ICONERROR
        invoke CloseSock
        invoke EnableControls
        ret
ShowErrorMessage ENDP
WriteOutputFile PROC buffer1:DWORD, BytesToWrite:DWORD
        .if ContentLength!=0
                mov eax,BytesToWrite
                add eax,CurrentDataSize
                .if eax>ContentLength
                        mov eax,ContentLength
                        sub eax,CurrentDataSize
                        mov BytesToWrite,eax
                .endif
        .endif
        invoke WriteFile,FileHandle,buffer1,\
                BytesToWrite,\
                addr BytesWritten,NULL                        
        push eax                
        .if eax==TRUE
                mov eax,BytesWritten                
                add CurrentDataSize,eax
                add ActualDataRead,eax
                invoke ShowProgress,hwnd
        .else
                invoke MessageBox,hwnd,addr WriteError,addr AppName,MB_OK+MB_ICONERROR
                invoke SetDlgItemText,hwnd,IDC_NAME,NULL
                invoke SetWindowText,hwndStatus,NULL                
        .endif
        pop eax
        ret
WriteOutputFile endp
;=====================================================================
;                               StrLen
;=====================================================================
; This procedure takes an address of a string as its parameter and
; returns the length of the string in eax
;=====================================================================
StrLen PROC uses edi String:DWORD
        mov edi,String
        mov al,0
        mov ecx,0FFFFFFFFh
        repne scasb
        sub ecx,0FFFFFFFFh
        neg ecx
        dec ecx
        mov eax,ecx
        ret
StrLen ENDP
;=====================================================================
;                               StrCpy
;=====================================================================
; This procedure copies a string into a buffer. If the buffer is smaller
; than the string to copy, it returns 0.
;=====================================================================
StrCpy PROC uses edi esi StrBuffer:DWORD,String:DWORD
        invoke StrLen,String
        mov ecx,eax
        mov edi,StrBuffer
        mov esi,String
        rep movsb
        ret
StrCpy ENDP
;=========================================================================
;                               InString
;=========================================================================
; Search for a substring in one string. Case Sensitive
; Return Value: -1 if substring not found, offset of the first byte
; of the substring if successful
;=========================================================================
InString PROC uses ebx edi esi StrMain:DWORD, StrSub:DWORD
        invoke StrLen,StrMain