asked on

POST a form using wininet.dll

How to submit a POST with Delphi and wininet.dll?

I believe I followed the recipe (from MSDN) very strictly, but indeed I did something wrong, because my code doesn't work. The input fields are correct, the host and object addresses are correct, no error is returned from any wininet routine, but the answer doesn't come. When I try the post through a proxy (a SQUID proxy) using INTERNET_OPEN_TYPE_PRECONFIG, it complains with a vague "Invalid Request". HTML returned follows.

<HTML><HEAD>
<TITLE>ERROR: The requested URL could not be retrieved</TITLE>
</HEAD><BODY>
<H1>ERROR</H1>
<H2>The requested URL could not be retrieved</H2>
<HR>
<P>
While trying to process the request:
<PRE>
POST http://10.0.65.31/susfone/listaserv.asp HTTP/1.1
Accept: , ,
Content-Type: application/x-www-form-urlencoded
</PRE>
<P>
The following error was encountered:
<UL>
<LI>
<STRONG>
Invalid Request
</STRONG>
</UL>

<P>
Some aspect of the HTTP Request is invalid. Possible problems:
<UL>
<LI>Missing or unknown request method
<LI>Missing URL
<LI>Missing HTTP Identifier (HTTP/1.0)
<LI>Request is too large
<LI>Content-Length missing for POST or PUT requests
<LI>Illegal character in hostname; underscores are not allowed
</UL>
<P>Your cache administrator is <A HREF="...(edited)...r">...</A>.

<br clear="all">
<hr noshade size=1>
Generated Wed, 26 Mar 2003 14:15:53 GMT by ...edited...MyCompany.com (Squid/2.4.STABLE6)
</BODY></HTML>

When I don't use the proxy (with INTERNET_OPEN_TYPE_DIRECT), the outcome is a timeout. With a browser (IE6), both with or without a proxy, the post works fine.

So, any suggestion?

My code is below.

Gilberto Silva

program poster0;
{$APPTYPE CONSOLE}
uses
SysUtils,
WinINet,
Windows,
supmon in 'supmon.pas';

const
url_objeto = 'susfone/listaserv.asp';
url_verbo = 'POST';
url_origem: array [0..99] of char = '10.0.65.31';
url_accept: array [0..99] of char = 'Accept: */*';
url_cttype: array [0..99] of char = 'Content-Type: application/x-www-form-urlencoded';
url_delay: dword = 10000;

var
i: integer;
nread: dword;
sessao, conexao, pedido: hinternet;
parnome, resnome, renavam, retorno: string;
parfile: textfile;
buffer: array [0..1023] of char;
renavdata: array [0..99] of char;
begin
// initialization, file open, etc ...
sessao := internetopen ('MyAgent', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if sessao = nil then
begin
// error handling ...
halt;
end;
InternetSetOption (sessao, INTERNET_OPTION_CONNECT_TIMEOUT, @url_delay, sizeof (dword));
InternetSetOption (sessao, INTERNET_OPTION_RECEIVE_TIMEOUT, @url_delay, sizeof (dword));
conexao := internetconnect (sessao, @url_origem, INTERNET_DEFAULT_HTTP_PORT, nil, nil,
INTERNET_SERVICE_HTTP, 0, 1);
if conexao = nil then ...
pedido := httpopenrequest (conexao, url_verbo, url_objeto, nil, nil, @url_accept, 0, 1);
if pedido = nil then ...
readln (parfile, renavam);
renavam := 'radfiltro=Sim&txtFiltro=' + renavam;
for i := 1 to length (renavam) do
renavdata [i -1] := renavam [i];
renavdata [length (renavam)] := #0;
if httpsendrequest (pedido, @url_cttype, sizeof (url_cttype), @renavdata, sizeof (renavdata)) then
begin
retorno := '';
repeat
buffer := #0;
if internetreadfile (pedido, @buffer, sizeof (buffer), nread) then
if nread > 0 then
retorno := retorno + buffer;
until nread = 0;
writeln (retorno);
end
else
writeln ('#GetLastError = ', getlasterror);
writeln;
internetclosehandle (pedido);
internetclosehandle (conexao);
internetclosehandle (sessao);
end.

emadat

Use this function:

//************************************************************************
function PostHTML(strURL: String): String;
const BufferSize = 1024;
var
hSession, hURL: HInternet;
Buffer: array[1..BufferSize] of Byte;
BufferLen: DWORD;
sResult: string;
mStrm: TMemoryStream;
begin
Result := '';
hSession := InternetOpen(PChar(sAppName), INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
if hSession<>nil then try
hURL := InternetOpenURL(hSession, PChar(strURL), nil, 0, 0, 0);
if hURL<>nil then try
sResult := '';
mStrm := TMemoryStream.Create;
try
repeat
InternetReadFile(hURL, @Buffer, SizeOf(Buffer), BufferLen);
if BufferLen>0 then mStrm.WriteBuffer(Buffer, BufferLen);
until BufferLen = 0;
SetLength(sResult, mStrm.Size);
CopyMemory(@sResult[1], mStrm.memory, mStrm.Size);
finally
mStrm.Free;
end;
Result := sResult;
finally
InternetCloseHandle(hURL);
end
finally
InternetCloseHandle(hSession);
end;
end;
//************************************************************************

gilberto_silva

ASKER

Sorry, emadat, but my concern isn't on how to retrieve the contents of a URL, but instead on how to submit a POST to an Active Server Page.

ASKER CERTIFIED SOLUTION

emadat

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emadat

Just modify the content type; and you are all set to go

gilberto_silva

ASKER

Ok, emadat, you deserve your points. It worked.

Gilberto Silva

gilberto_silva

ASKER

Maybe the only - and crucial - difference from my code was the use of a tMemoryStrem instead of an array of char. Anyway, sometimes a little point makes all the difference. Thank you, emadat!

Gilberto Silva

emadat

Not at all.
My pleasure