Hi.
I want to write a limited internet browser using the internet functions
provided by winapi.
I have a problem sending a html form. There are two methods how to send a
form in html: "get" which only calls a simple URL and "post". Post does
obviously not send the data within the URL, it somehow sends it later.
Does anybody know how to transmit data in a form with winapi using the
post-method?
Thanks a lot for your help in advance,
Sebastian

Hi Sebastian,

Maybe the following function helps for getting started. I wrote it for use in Office VBA and it downloads the data directly into the
clipboard for pasting them into Excel/World but you could adjusted it for your purposes:

(by the way the "post"ed data are also transmitted at the same time but in the HTTP header)

-----------------------------------------------------------------------------
Option Explicit

Private Declare Function OpenClipboard _
                Lib "user32" _
              ( _
                ByVal hWnd As Long _
              ) _
                As Long

Private Declare Function CloseClipboard _
                Lib "user32" () _
                As Long

Private Declare Function EmptyClipboard _
                Lib "user32" () _
                As Long

Private Declare Function SetClipboardData _
                Lib "user32" _
              ( _
                ByVal wFormat As Long, _
                ByVal hMem As Long _
              ) _
                As Long

Private Declare Function InternetOpen _
                Lib "wininet.dll" _
                Alias "InternetOpenA" _
              ( _
                ByVal lpszCallerName As String, _
                ByVal dwAccessType As Long, _
                ByVal lpszProxyName As String, _
                ByVal lpszProxyBypass As String, _
                ByVal dwFlags As Long _
              ) _
                As Long

Private Declare Function InternetConnect _
                Lib "wininet.dll" _
                Alias "InternetConnectA" _
              ( _
                ByVal hInternetSession As Long, _
                ByVal lpszServerName As String, _
                ByVal nProxyPort As Integer, _
                ByVal lpszUsername As String, _
                ByVal lpszPassword As String, _
                ByVal dwService As Long, _
                ByVal dwFlags As Long, _
                ByVal dwContext As Long _
               ) _
                As Long

Private Declare Function InternetReadFile _
                Lib "wininet.dll" _
              ( _
                ByVal hFile As Long, _
                ByVal sBuffer As String, _
                ByVal lNumBytesToRead As Long, _
                lNumberOfBytesRead As Long _
              ) _
                As Integer

Private Declare Function HttpOpenRequest _
                Lib "wininet.dll" _
                Alias "HttpOpenRequestA" _
              ( _
                ByVal hInternetSession As Long, _
                ByVal lpszVerb As String, _
                ByVal lpszObjectName As String, _
                ByVal lpszVersion As String, _
                ByVal lpszReferer As String, _
                ByVal lpszAcceptTypes As Long, _
                ByVal dwFlags As Long, _
                ByVal dwContext As Long _
              ) _
                As Long

Private Declare Function HttpSendRequest Lib "wininet.dll" _
                Alias "HttpSendRequestA" _
              ( _
                ByVal hHttpRequest As Long, _
                ByVal HttpPost_Headers As String, _
                ByVal lHeadersLength As Long, _
                ByVal sOptional As String, _
                ByVal lOptionalLength As Long _
              ) _
                As Boolean

Private Declare Function InternetCloseHandle _
                Lib "wininet.dll" _
              ( _
                ByVal hInternetHandle As Long _
              ) _
                As Boolean

Private Declare Function HttpAddRequestHeaders _
                Lib "wininet.dll" _
                Alias "HttpAddRequestHeadersA" _
              ( _
                ByVal hHttpRequest As Long, _
                ByVal HttpPost_Headers As String, _
                ByVal lHeadersLength As Long, _
                ByVal lModifiers As Long _
              ) _
                As Integer

Private Declare Function GlobalAlloc _
                Lib "kernel32" _
              ( _
                ByVal wFlags As Long, _
                ByVal dwBytes As Long _
              ) _
                As Long

Private Declare Function GlobalLock _
                Lib "kernel32" _
              ( _
                ByVal hMem As Long _
              ) _
                As Long

Private Declare Sub CopyMemory _
                Lib "kernel32" _
                Alias "RtlMoveMemory" _
              ( _
                Destination As Any, _
                Source As Any, _
                ByVal Length As Long _
              )

Private Declare Function GlobalUnlock _
                Lib "kernel32" _
              ( _
                ByVal hMem As Long _
              ) _
                As Long

Public Function fncPostandDownloadtoClipboard _
              ( _
                ServerName As String, _
                EngineFullName As String, _
                PostParameters As String _
              ) _
                As Integer
 'function that posts a request to a server engine and
 'downloads the responce directly into the clipboard;
 'application enabled to 'read' CF_HTML format can convert
 'the clipboard contents subsequently
 '
 'declaration of variables
  Dim InternetOpen_hWnd         As Long
  Dim InternetConnect_hWnd      As Long
  Dim HttpOpenRequest_hWnd      As Long
  Dim HttpSendRequest_Result    As Boolean
  Dim ContinueDataCollection    As Boolean
  Dim DataChunkRetrieved        As Boolean
  Dim NumberOfBytestoRead       As String * 2048
  Dim NumberOfBytesRead         As Long
  Dim ServerResponce            As String
  Dim MemoryType                As Long
  Dim MemoryHeap                As Long
  Dim VirtualTextLocation       As Long
 '
 'custom error codes
  Const Success = 1
  Const Error_UnexpectedError = 0
  Const Error_InternetSessionFailed = (-1)
  Const Error_ServerConnectionFailed = (-2)
  Const Error_HttpRequestOpenFailed = (-3)
  Const Error_HttpRequestSendFailed = (-4)
  Const Error_OpenClipboardFailed = (-5)
 '
 'Win32 API constants
  Const HttpPost_Header = "Content-Type: application/x-www-form-urlencoded"
  Const INTERNET_OPEN_TYPE_PRECONFIG = 0
  Const INTERNET_SERVICE_HTTP = 3
  Const INTERNET_DEFAULT_HTTP_PORT = 80
  Const INTERNET_FLAG_RELOAD = &H80000000
  Const HTTP_ADDREQ_FLAG_ADD = &H20000000
  Const HTTP_ADDREQ_FLAG_REPLACE = &H80000000
  Const CF_TEXT = 1
  Const GMEM_SHARE = &H2000&
  Const GMEM_MOVEABLE = &H2
  Const GMEM_ZEROINIT = &H40
 '
 'initialize the result of the function to Error_UnexpectedError;
 'assume unexpected error
  fncPostandDownloadtoClipboard = Error_UnexpectedError
 '
 'initialize other variables wininet.dll
  InternetOpen_hWnd = 0
 '
 'initiate an intenet session with wininet.dll
  InternetOpen_hWnd = InternetOpen _
                    ( _
                      lpszCallerName:="http generic", _
                      dwAccessType:=INTERNET_OPEN_TYPE_PRECONFIG, _
                      lpszProxyName:=vbNullString, _
                      lpszProxyBypass:=vbNullString, _
                      dwFlags:=0 _
                    )
 '
 'if a new internet session with wininet.dll could not be established
 'exit the function and return Error_InternetSessionFailed
  If InternetOpen_hWnd = 0 Then
     fncPostandDownloadtoClipboard = Error_InternetSessionFailed
     Exit Function
  End If
 '
 'establish a connection to the server
  InternetConnect_hWnd = InternetConnect _
                   ( _
                     hInternetSession:=InternetOpen_hWnd, _
                     lpszServerName:=ServerName, _
                     nProxyPort:=INTERNET_DEFAULT_HTTP_PORT, _
                     lpszUsername:=vbNullString, _
                     lpszPassword:="HTTP/1.0", _
                     dwService:=INTERNET_SERVICE_HTTP, _
                     dwFlags:=0, _
                     dwContext:=0 _
                   )
 '
 'if a connection with the remote server could not be established
 'terminate the internet session with wininet.dll,
 'return Error_ServerConnectionFailed and exit the function
  If InternetConnect_hWnd = 0 Then
     Call InternetCloseHandle(hInternetHandle:=InternetOpen_hWnd)
     fncPostandDownloadtoClipboard = Error_ServerConnectionFailed
     Exit Function
  End If
 '
 'open a 'HttpRequest' object of "post" type with target engine (ASP etc.)
 'in the remote server
  HttpOpenRequest_hWnd = HttpOpenRequest _
                   ( _
                     hInternetSession:=InternetConnect_hWnd, _
                     lpszVerb:="POST", _
                     lpszObjectName:=EngineFullName, _
                     lpszVersion:="HTTP/1.0", _
                     lpszReferer:=vbNullString, _
                     lpszAcceptTypes:=0, _
                     dwFlags:=INTERNET_FLAG_RELOAD, _
                     dwContext:=0 _
                   )
 '
 'if a 'HttpRequest' object could not be created then
 'terminate the internet session with wininet.dll,
 'return Error_HttpRequestOpenFailed and exit the function
  If HttpOpenRequest_hWnd = 0 Then
     Call InternetCloseHandle(hInternetHandle:=InternetOpen_hWnd)
     fncPostandDownloadtoClipboard = Error_HttpRequestOpenFailed
     Exit Function
  End If
 '
 'an Internet client application that posts HTML form data to a remote server
 'must add a "Content-Type: application/x-www-form-urlencoded" HTTP header in
 'the POST request; so we added in the 'HttpRequest' object we have opened
  Call HttpAddRequestHeaders _
                   ( _
                     hHttpRequest:=HttpOpenRequest_hWnd, _
                     HttpPost_Headers:=HttpPost_Header & vbCrLf, _
                     lHeadersLength:=Len(HttpPost_Header & vbCrLf), _
                     lModifiers:=HTTP_ADDREQ_FLAG_REPLACE Or HTTP_ADDREQ_FLAG_ADD _
                   )
 '
 'post the constructed request to the remote serever
  HttpSendRequest_Result = CBool( _
                  HttpSendRequest _
                   ( _
                     hHttpRequest:=HttpOpenRequest_hWnd, _
...

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