How to use WinInet from Lazarus? Download a file and POST
lazarus / 38-Networking and Web Programming

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Igor · 2018-10-29 12:44

Hi,

Is it possible to use WinInet API from Lazarus to download a file from
HTTPS server, or perform POST query (to implement online activation
for my product).

I tried fphttpclient, but it requires OpenSSL dlls.

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sstvmaster · 2018-10-29 13:01

You can download OpenSSL file here: https://indy.fulgan.com/SSL/
(openssl-1.0.2p-...)

Download version win32 or win64, unzip and copy libeayXX.dll and
ssleayXX.dll in your program folder.

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Igor · 2018-10-29 13:31

Thanks,

Yes, it worked.

But is it possible to use WinInet in Lazarus?

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Thaddy · 2018-10-29 13:44

Yes it is!... but only on Windows. (I believe it is also deprecated by
microsoft, at least for serverside applications. See:
https://msdn.microsoft.com/library/windows/desktop/aa384273  and
https://docs.microsoft.com/en-us/windows/desktop/WinInet/enabling-
internet-functionality )
Unless you have a reason, don't use it since it is not cross-platform.
fcl-net / fcl-web and synapse and indy are all cross-platform.

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Igor · 2018-10-29 13:55

Thanks for you reply!

What is best and simpliest cross-platform API (Win + macOS) just to
download a file, or perform POST request to a server?

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fred · 2018-10-29 14:09

Simpliest would be SimpleGet:
http://wiki.lazarus.freepascal.org/fphttpclient

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Thaddy · 2018-10-29 15:11

Quote from: fred on October 29, 2018, 03:09:36 pmSimpliest would be
SimpleGet:
http://wiki.lazarus.freepascal.org/fphttpclient
Yes, maybe, but atm. the synapse solution is still simpler since
simpleget does not allow for redirects (yet). So you can get the
dreaded 403...
As I wrote before, this one allows https, redirects and works almost
always;Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {$ifdef
fpc}{$mode delphi}{$H+}{$endif}uses classes, httpsend,
ssl_openssl;var  l:Tstrings;begin  try    l:=Tstringlist.create;    if
HttpGetText('https://www.google.com',L) then  // this has a
redirection as well as ssl enabled.      writeln(l.text);  finally   
l.free;  end;end.
That said, the same can be done will a slight modification of the
SimpleGet code. I'll see if I can submit a patch.

In the above code you may want to use httpgetbinary to download a
file, btw. And use a stream. This was just for illustration.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {$ifdef
fpc}{$mode delphi}{$H+}{$endif}uses classes, httpsend,
ssl_openssl;var  S:TStream;  l:Tstrings;begin   
S:=TFilestream.Create('testme.bin', fmCreate or fmOpenWrite);    
L:=TStringlist.create;    try    if
HttpGetBinary('https://www.google.com',S) then    begin      S.Free; 
   L.LoadFromFile('testme.bin');      writeln(l.text);    end; 
finally    l.free;  end;end.
Note that I mixed the two but the essential part is how to download in
binary format. (Q & D) But cross-platform.

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Igor · 2018-10-30 11:16

Thanks for your recommendations! I will check it.

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Hansaplast · 2019-11-27 12:51

A little late, but I was looking for an "easy" way to download a file
from a webserver using HTTPS and ran into this topic.


Under more recent macOS versions (at least as of Mojave), fphttpclient
will not work.
Apple does not seem to like the OpenSSL library (default macOS
setup!):


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Invalid
dylib load. Clients should not load the unversioned libcrypto dylib as
it does not have a stable ABI.

As an alternative for macOS users, use the unit "ns_url_request" by
Phil Hess (can be found here - Phil's Mac related page).
This does not require any extra libraries (beyond what comes with
macOS).


A quick (and sloppy) function pulling in HTTPS content as a string:


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i uses ...
ns_url_request ... // Note: "ns_url_request" uses Phil's "NSHelpers"
unit.  ...  function TForm1.GetURLContent(aURL:string):string;var 
HTTP: TNSHTTPSendAndReceive;begin  HTTP :=
TNSHTTPSendAndReceive.Create;  HTTP.Method   := 'GET';  HTTP.Address
 := aURL;  HTTP.SendAndReceive(Result);  HTTP.Free;end;

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trev · 2019-12-04 12:31

Quote from: Hansaplast on November 27, 2019, 01:51:25 pmUnder more
recent macOS versions (at least as of Mojave), fphttpclient will not
work.

Works for me in macOS (Mojave, Catalina), FreeBSD and Linux. Note: I'm
using trunk (see below).

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trev · 2019-12-04 12:33

Quote from: Igor Kokarev on October 29, 2018, 01:44:12 pmIs it
possible to use WinInet API from Lazarus to download a file from HTTPS
server, or perform POST query (to implement online activation for my
product).

Yes! See below:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {$IFDEF
WINDOWS}// Need to use Windows WinInet to avoid issue with HTTPS//
needing two OpenSSL DLLs to be provided with application// if using
TFPHttpClient.// The WinINet API also gets any connection and proxy
settings// set by Internet Explorer. Blessing or curse? function
GetWebPage(const Url: string): string;var  NetHandle: HINTERNET; 
UrlHandle: HINTERNET;  Buffer: array[0..1023] of Byte;  BytesRead:
dWord;  StrBuffer: UTF8String;begin  Result := '';  BytesRead :=
Default(dWord);  NetHandle := InternetOpen('Mozilla/5.0(compatible;
WinInet)', INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);   // NetHandle
valid?  if Assigned(NetHandle) then    Try      UrlHandle :=
InternetOpenUrl(NetHandle, PChar(Url), nil, 0, INTERNET_FLAG_RELOAD,
0);       // UrlHandle valid?      if Assigned(UrlHandle) then       
Try          repeat            InternetReadFile(UrlHandle, @Buffer,
SizeOf(Buffer), BytesRead);            SetString(StrBuffer,
PAnsiChar(@Buffer[0]), BytesRead);            Result := Result +
StrBuffer;          until BytesRead = 0;        Finally         
InternetCloseHandle(UrlHandle);        end      // o/w UrlHandle
invalid      else        ShowMessage('Cannot open URL: ' + Url);   
Finally      InternetCloseHandle(NetHandle);    end  // NetHandle
invalid  else    raise Exception.Create('Unable to initialize
WinInet');end;{$ENDIF}

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Hansaplast · 2019-12-04 12:45

Hmm, interesting. My Mac's (Catalina) complain with the above error  
...
Phil wrote a small document on sandboxing and macOS (link) where he
states as well;
QuoteOpenSSL on Mac has been deprecated for a long time, so you should
be using one of Apple's APIs instead

And he refers to an Apple document from June 2018, indicating OpenSSL
is deprecated and its use is "strongly" discouraged:
Quote ... OpenSSL is deprecated in macOS and is not provided in iOS.
Use of the Apple-provided OpenSSL libraries by apps is strongly
discouraged.

Granted; Sandbox is not the same as non-Sandbox apps, but I did run
into issues with my regular apps as well (not sandboxed, not in the
Apple Store) and Phils code resolved it.


p.s. Thanks Trev for the WinInet code example - I'll give that a try
as well (under Windows of course)

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trev · 2019-12-04 12:56

Quote from: Hansaplast on December 04, 2019, 01:45:48 pmHmm,
interesting. My Mac's (Catalina) complain with the above error 

Here's the code I use without any issues on macOS, FreeBSD and Linux:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {$IFDEF
UNIX}function GetWebPage(const aURL: string): string;var  Client:
TFPHttpClient;begin  Client := TFPHttpClient.Create(nil);   Try   
Client.AllowRedirect := true;    Client.AddHeader('User-Agent',
'Mozilla/5.0(compatible; fpweb)');    Result := Client.Get(aURL); 
except      on E: Exception do           ShowMessage('Retrieval of: '
+ aURL + LineEnding                       + 'Failed with error: ' +
E.Message + LineEnding                       + 'HTTP code: ' +
IntToSTr(Client.ResponseStatusCode));  end;end;{$ENDIF} 
Quotep.s. Thanks Trev for the WinInet code example - I'll give that a
try as well (under Windows of course) 

Glad to help

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MISV · 2019-12-05 20:58

Have you checked this thread.

https://community.idera.com/developer-tools/platforms/f/macos-
platform/70310/issue-with-using-indy-on-catalina

It is two months old where Remy mentions having introduced a fix / new
function call in Indy

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BeniBela · 2019-12-10 11:49

My Internet Tools use wininet for downloading