I am trying to create https server in lazarus using synapse but I am failing. I want to mys server receive data from other https clients.
I am sending requests with my browser using https://localhost:1500 and mys server is receiving signals. But when I try to read sent data I receive nothing. When I tested simple http server all worked fine. But now in case of https it is not working. I am using ubuntu 15.04 as my OS
s := ASocket.RecvString(timeout); //returns noething
My sample code:
unit Unit1;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, StdCtrls;
type
{ TForm1 }
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ private declarations }
public
{ public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
uses
blcksock, sockets, Synautil, ssl_openssl, ssl_openssl_lib;
procedure AttendConnection(ASocket: TTCPBlockSocket);
var
timeout: integer;
s: string;
method, uri, protocol: string;
OutputDataString: string;
ResultCode: integer;
begin
timeout := 1000;
WriteLn('Received headers+document from browser:');
//read request line
s := ASocket.RecvString(timeout);
WriteLn(s);
method := fetch(s, ' ');
uri := fetch(s, ' ');
protocol := fetch(s, ' ');
//read request headers
repeat
s := ASocket.RecvString(Timeout);
WriteLn(s);
until s = '';
// Now write the document to the output stream
if uri = '/' then
begin
// Write the output document to the stream
OutputDataString :=
'<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"'
+ ' "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">' + CRLF
+ '<html><h1>Teste</h1></html>' + CRLF;
// Write the headers back to the client
ASocket.SendString('HTTP/1.0 200' + CRLF);
ASocket.SendString('Content-type: Text/Html' + CRLF);
ASocket.SendString('Content-length: ' + IntTostr(Length(OutputDataString)) + CRLF);
ASocket.SendString('Connection: close' + CRLF);
ASocket.SendString('Date: ' + Rfc822DateTime(now) + CRLF);
ASocket.SendString('Server: Servidor do Felipe usando Synapse' + CRLF);
ASocket.SendString('' + CRLF);
// if ASocket.lasterror <> 0 then HandleError;
// Write the document back to the browser
ASocket.SendString(OutputDataString);
end
else
ASocket.SendString('HTTP/1.0 404' + CRLF);
end;
{ TForm1 }
procedure TForm1.Button1Click(Sender: TObject);
var
ListenerSocket, ConnectionSocket: TTCPBlockSocket;
begin
ListenerSocket := TTCPBlockSocket.Create;
ConnectionSocket := TTCPBlockSocket.Create;
ListenerSocket.CreateSocket;
ListenerSocket.SSL.CertificateFile := '/home/imants/projects/apps/medieval/bin/40669199_localhost_8080.cert';
ListenerSocket.SSL.PrivateKeyFile := '/home/imants/projects/apps/medieval/bin/40669199_localhost_8080.key';
ListenerSocket.SSLDoConnect;
ListenerSocket.setLinger(true,10);
ListenerSocket.bind('localhost','1500');
ListenerSocket.listen;
repeat
if ListenerSocket.canread(1000) then
begin
ConnectionSocket.Socket := ListenerSocket.accept;
WriteLn('Attending Connection. Error code (0=Success): ', ConnectionSocket.lasterror);
AttendConnection(ConnectionSocket);
ConnectionSocket.CloseSocket;
end;
until false;
ListenerSocket.Free;
ConnectionSocket.Free;
end;
end.
There are two sources, that I know of, with an example for a HTTP(s) server in Synapse.
The first example is in the Synapse stable package (release 40). Although I would recommend you use the SVN version (you can use the Download Snapshot button on that page) you can still use the examples in the "release 40 package".
The example in synapse40\source\demo\httpsserv should be usable as HTTPS-server. If it's not you could take the httpserv (HTTP) example and change it as shown here. (But I think the httpsserv is just the same with those modifications)
If you're on Linux (Lazarus) you'll need to change every occurrence of winsock to synsock and remove any windows-clause.
Another example can be found here. (Direct download of SynHttp.zip) As far as I could see it also has HTTPS-server functionality.
I know that you want to use Synapse, but you may want to take a look at Indy. I have been developing server/client apps with indy for some years and I like it. It's working fine with windows and linux (32bit, 64bit, arm...) and has some nice features. You could use the TIdHTTPServer component. Moreover get an IOHandlerSSLOpenSSL. The event OnCommandGet(AContext: TIdContext;
ARequestInfo: TIdHTTPRequestInfo; AResponseInfo: TIdHTTPResponseInfo) is the most important one. It allows access to the Request (like A ARequestInfo.Document) and to your HTTP response (AResponseInfo).
Related
I m looking for a way to improve the navigation between different tools (under windows). I would like to add in the body of an email a special "link" that when the user will click on it will launch my delphi app installed in his local computer. Is it possible and if yes how to do?
Yes, it is possible. Your application must create a moniker (for example, from its setup or first launch). This will allow the mail client to open an URL pointing to your application, and Windows will launch it and pass the URL to it.
Here is some source code to register/unregister the URL protocol:
function RegisterURLProtocol(
const ProtocolID : String;
const ProtocolName : String;
const DefaultIcon : String;
const OpenCommand : String) : Boolean;
var
Reg : TRegistry;
begin
Result := FALSE;
Reg := TRegistry.Create(KEY_WRITE);
try
Reg.RootKey := HKEY_CLASSES_ROOT;
if not Reg.OpenKey(ProtocolID, TRUE) then
Exit;
Reg.WriteString('', 'URL:' + ProtocolName);
Reg.WriteString('URL Protocol', '');
if Reg.OpenKey('DefaultIcon', True) then begin
Reg.WriteString('', DefaultIcon);
end;
Reg.CloseKey;
if not Reg.OpenKey(ProtocolID + '\shell\open\command', True) then
Exit;
Reg.WriteString('', OpenCommand);
Result := TRUE;
finally
FreeAndNil(Reg);
end;
end;
function UnregisterURLProtocol(
const ProtocolID : String) : Boolean;
var
Reg : TRegistry;
begin
Result := FALSE;
Reg := TRegistry.Create(KEY_WRITE);
try
Reg.RootKey := HKEY_CLASSES_ROOT;
if not Reg.KeyExists(ProtocolID) then
Exit;
Reg.DeleteKey(ProtocolID + '\DefaultIcon');
Reg.DeleteKey(ProtocolID + '\shell\open\command');
Reg.DeleteKey(ProtocolID + '\shell\open');
Reg.DeleteKey(ProtocolID + '\shell');
Reg.DeleteKey(ProtocolID);
Result := TRUE;
finally
FreeAndNil(Reg);
end;
end;
ProtocolID is the identifier for your protocol. You can use something like 'MyApp'. If you had to register the HTTP protocol, you would use 'http'. The application will be opened by Windows when the user clicks on the link. The application will receive what is specified by the OpenCommand (A string you specify). You can include %1 in that OpenCommand and it will be replaced by the URL except the protocol.
ProtocolName is a string describing your protocol.
The URL to place in the mail would be like this:
MyApp://SomeParameters/SomeMoreParameters
I have a room with 60 computers/devices (40 computers and 20 oscilloscopes Windows CE based) and I would like to know which and every one is alive using ping. First I wrote a standard ping (see here Delphi Indy Ping Error 10040), which is working fine now but takes ages when most computers are offline.
So what I am trying to do is to write a MultiThread Ping but I am quite struggling with it. I have seen only very few examples over the internet and no one was matching my needs, that's why I try to write it myself.
I use XE2 and Indy 10 and the form is only constitued of a memo and a button.
unit Main;
interface
uses
Winapi.Windows, System.SysUtils, System.Classes, Vcl.Forms,
IdIcmpClient, IdGlobal, Vcl.StdCtrls, Vcl.Controls;
type
TMainForm = class(TForm)
Memo1: TMemo;
ButtonStartPing: TButton;
procedure ButtonStartPingClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
type
TMyPingThread = class(TThread)
private
fIndex : integer;
fIdIcmpClient: TIdIcmpClient;
procedure doOnPingReply;
protected
procedure Execute; override;
public
constructor Create(index: integer);
end;
var
MainForm: TMainForm;
ThreadCOunt : integer;
implementation
{$R *.dfm}
constructor TMyPingThread.Create(index: integer);
begin
inherited Create(false);
fIndex := index;
fIdIcmpClient := TIdIcmpClient.Create(nil);
fIdIcmpClient.ReceiveTimeout := 200;
fIdIcmpClient.PacketSize := 24;
fIdIcmpClient.Protocol := 1;
fIdIcmpClient.IPVersion := Id_IPv4;
//first computer is at adresse 211
fIdIcmpClient.Host := '128.178.26.'+inttostr(211+index-1);
self.FreeOnTerminate := true;
end;
procedure TMyPingThread.doOnPingReply;
begin
MainForm.Memo1.lines.add(inttostr(findex)+' '+fIdIcmpClient.ReplyStatus.Msg);
dec(ThreadCount);
if ThreadCount = 0 then
MainForm.Memo1.lines.add('--- End ---');
end;
procedure TMyPingThread.Execute;
begin
inherited;
try
fIdIcmpClient.Ping('',findex);
except
end;
while not Terminated do
begin
if fIdIcmpClient.ReplyStatus.SequenceId = findex then Terminate;
end;
Synchronize(doOnPingReply);
fIdIcmpClient.Free;
end;
procedure TMainForm.ButtonStartPingClick(Sender: TObject);
var
i: integer;
myPing : TMyPingThread;
begin
Memo1.Lines.Clear;
ThreadCount := 0;
for i := 1 to 40 do
begin
inc(ThreadCount);
myPing := TMyPingThread.Create(i);
//sleep(10);
end;
end;
end.
My problem is that it "seems" to work when I uncomment the "sleep(10)", and "seems" not to be working without it. This for sure means I am missing a point in the threading I have written.
In other words. When Sleep(10) is in the code. Every time I clicked the button to get to check the connections the result was correct.
Without the sleep(10), it is working "most" of the time but some times the result is wrong giving me a ping echo on offline computers and no ping echo on online computer, as is the ping reply was not assigned to the correct thread.
Any comment or help is welcome.
----- EDIT / IMPORTANT -----
As a general follow up of this question, #Darian Miller started a Google Code project here https://code.google.com/p/delphi-stackoverflow/ which is a working basis. I mark his answer as the "accepted answer" but users should refer to this open source project (all the credit belongs to him) as it will surely be extended and updated in the future.
The root problem is that pings are connectionless traffic. If you have multiple TIdIcmpClient objects pinging the network at the same time, one TIdIcmpClient instance can receive a reply that actually belongs to another TIdIcmpClient instance. You are trying to account for that in your thread loop, by checking SequenceId values, but you are not taking into account that TIdIcmpClient already does that same check internally. It reads network replies in a loop until it receives the reply it is expecting, or until the ReceiveTimeout occurs. If it receives a reply it is not expecting, it simply discards that reply. So, if one TIdIcmpClient instance discards a reply that another TIdIcmpClient instance was expecting, that reply will not get processed by your code, and that other TIdIcmpClient will likely receive another TIdIcmpClient's reply instead, and so on. By adding the Sleep(), you are decreasing (but not eliminating) the chances that pings will overlap each other.
For what you are attempting to do, you won't be able to use TIdIcmpClient as-is to have multiple pings running in parallel, sorry. It is simply not designed for that. There is no way for it to differentiate reply data the way you need it. You will have to serialize your threads so only one thread can call TIdIcmpClient.Ping() at a time.
If serializing the pings is not an option for you, you can try copying portions of TIdIcmpClient's source code into your own code. Have 41 threads running - 40 device threads and 1 response thread. Create a single socket that all of the threads share. Have each device thread prepare and send its individual ping request to the network using that socket. Then have the response thread continuously reading replies from that same socket and routing them back to the appropriate device thread for processing. This is a bit more work, but it will give you the multiple-ping parallelism you are looking for.
If you don't want to go to all that trouble, an alternative is to just use a third-party app that already supports pinging multiple machines at the same time, like FREEPing.
Remy explained the problems... I've wanted to do this in Indy for a while so I posted a possible solution that I just put together to a new Google Code project instead of having a long comment here. It's a first-stab sort of thing, let me know if you have some changes to integrate:
https://code.google.com/p/delphi-vault/
This code has two ways to Ping...multi-threaded clients as in your example, or with a simple callback procedure. Written for Indy10 and later versions of Delphi.
Your code would end up using a TThreadedPing descendant defining a SynchronizedResponse method:
TMyPingThread = class(TThreadedPing)
protected
procedure SynchronizedResponse(const ReplyStatus:TReplyStatus); override;
end;
And to fire off some client threads, the code becomes something like:
procedure TfrmThreadedPingSample.butStartPingClick(Sender: TObject);
begin
TMyPingThread.Create('www.google.com');
TMyPingThread.Create('127.0.0.1');
TMyPingThread.Create('www.shouldnotresolvetoanythingatall.com');
TMyPingThread.Create('127.0.0.1');
TMyPingThread.Create('www.microsoft.com');
TMyPingThread.Create('127.0.0.1');
end;
The threaded response is called in a synchronized method:
procedure TMyPingThread.SynchronizedResponse(const ReplyStatus:TReplyStatus);
begin
frmThreadedPingSample.Memo1.Lines.Add(TPingClient.FormatStandardResponse(ReplyStatus));
end;
I did not try your code, so that is all hypothetical, but i think you messed the threads and got classic race condition. I restate my advice to use AsyncCalls or OmniThreadLibrary - they are much simpler and would save you few attempts at "shooting your own foot".
Threads are made to minimize main-thread load. Thread constructor should do minimal work of remembering parameters. Personally i'd moved idICMP creation into .Execute method. If for any reason it would want to create its internal synchronization objects, like window and message queue or signal or whatever, i'd like it to happen already in a new spawned thread.
There is no sense for "inherited;" in .Execute. Better remove it.
Silencing all exceptions is bad style. You probably have errors - but have no way to know about them. You should propagate them to main thread and display them. OTL and AC help you in that, while for tThread you have to do it manually. How to Handle Exceptions thrown in AsyncCalls function without calling .Sync?
Exception logic is flawed. There is no point to have a loop if exception thrown - if no succesful Ping was set - then why waiting for response ? You loop should go within same try-except frame as issuing ping.
Your doOnPingReply executes AFTER fIdIcmpClient.Free yet accesses fIdIcmpClient's internals. Tried changing .Free for FreeAndNil ?
That is a classic mistake of using dead pointer after freeing it.
The correct approach would be to:
5.1. either free the object in doOnPingReply
5.2. or copy all relevant data from doOnPingReply to TThread's private member vars before calling both Synchronize and idICMP.Free (and only use those vars in doOnPingReply )
5.3. only do fIdIcmpClient.Free inside TMyThread.BeforeDestruction or TMyThread.Destroy. Afterall, if you chosen to create the object in constructor - then you should free it in the matching language construct - destructor.
Since you do not keep references to the thread objects - that While not Terminated loop seems redundant. Just make usual forever-loop and call break.
The aforementioned loop is CPU-hungry, it is like spin-loop. Please call Sleep(0); or Yield(); inside loop to give other threads better chance to do their work. Don't work agaisnt OS scheduler here - you are not in a speed-critical path, no reason to make spinlock here.
Overall, i consider:
4 and 5 as critical bugs for you
1 and 3 as a potential gotcha maybe influencing or maybe not. You'd better 'play safe' rather than doing risky things and investigating if they would work or not.
2 and 7 - bad style, 2 regarding language and 7 regarding platform
6 either you have plans to extend your app, or you broke YAGNI principle, dunno.
Sticking with complex TThread instead of OTL or AsyncCalls - strategic errors. Don't you put rooks on your runway, use simple tools.
Funny, this is example of the bug that FreeAndNil could expose and make obvious, while FreeAndNil-haters are claiming it "conceals" bugs.
// This is my communication unit witch works well, no need to know its work but your
// ask is in the TPingThread class.
UNIT UComm;
INTERFACE
USES
Windows, Messages, SysUtils, Classes, Graphics, Controls, ExtCtrls, Forms, Dialogs,
StdCtrls,IdIcmpClient, ComCtrls, DB, abcwav, SyncObjs, IdStack, IdException,
IdTCPServer, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, IdContext,
UDM, UCommon;
TYPE
TNetworkState = (nsNone, nsLAN, nsNoLAN, nsNet, nsNoNet);
TDialerStatus = (dsNone, dsConnected, dsDisconnected, dsNotSync);
{ TBaseThread }
TBaseThread = Class(TThread)
Private
FEvent : THandle;
FEventOwned : Boolean;
Procedure ThreadTerminate(Sender: TObject); Virtual;
Public
Constructor Create(AEventName: String);
Property EventOwned: Boolean Read FEventOwned;
End;
.
.
.
{ TPingThread }
TPingThread = Class(TBaseThread)
Private
FReply : Boolean;
FTimeOut : Integer;
FcmpClient : TIdIcmpClient;
Procedure ReplyEvent(Sender: TComponent; Const AReplyStatus: TReplyStatus);
Protected
Procedure Execute; Override;
Procedure ThreadTerminate(Sender: TObject); Override;
Public
Constructor Create(AHostIP, AEventName: String; ATimeOut: Integer);
Property Reply: Boolean Read FReply;
End;
.
.
.
{ =============================================================================== }
IMPLEMENTATION
{$R *.dfm}
USES
TypInfo, WinSock, IdGlobal, UCounter, UGlobalInstance, URemoteDesktop;
{IdGlobal: For RawToBytes function 10/07/2013 04:18 }
{ TBaseThread }
//---------------------------------------------------------
Constructor TBaseThread.Create(AEventName: String);
Begin
SetLastError(NO_ERROR);
FEvent := CreateEvent(Nil, False, False, PChar(AEventName));
If GetLastError = ERROR_ALREADY_EXISTS
Then Begin
CloseHandle(FEvent);
FEventOwned := False;
End
Else If FEvent <> 0 Then
Begin
FEventOwned := True;
Inherited Create(True);
FreeOnTerminate := True;
OnTerminate := ThreadTerminate;
End;
End;
//---------------------------------------------------------
Procedure TBaseThread.ThreadTerminate(Sender: TObject);
Begin
CloseHandle(FEvent);
End;
{ TLANThread }
.
.
.
{ TPingThread }
//---------------------------------------------------------
Constructor TPingThread.Create(AHostIP: String; AEventName: String; ATimeOut: Integer);
Begin
Inherited Create(AEventName);
If Not EventOwned Then Exit;
FTimeOut := ATimeOut;
FcmpClient := TIdIcmpClient.Create(Nil);
With FcmpClient Do
Begin
Host := AHostIP;
ReceiveTimeOut := ATimeOut;
OnReply := ReplyEvent;
End;
End;
//---------------------------------------------------------
Procedure TPingThread.Execute;
Begin
Try
FcmpClient.Ping;
FReply := FReply And (WaitForSingleObject(FEvent, FTimeOut) = WAIT_OBJECT_0);
Except
FReply := False;
End;
End;
//---------------------------------------------------------
Procedure TPingThread.ReplyEvent(Sender: TComponent; Const AReplyStatus: TReplyStatus);
Begin
With AReplyStatus Do
FReply := (ReplyStatusType = rsEcho) And (BytesReceived <> 0);
SetEvent(FEvent);
End;
//---------------------------------------------------------
Procedure TPingThread.ThreadTerminate(Sender: TObject);
Begin
FreeAndNil(FcmpClient);
Inherited;
End;
{ TNetThread }
.
.
.
I'm trying to upload a file .txt in my web space, but then the problems start, the code I tried is this:
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient,
IdExplicitTLSClientServerBase, IdFTP, StdCtrls;
procedure TForm1.Button1Click(Sender: TObject);
var
FTP:tidftp;
begin
FTP.Host:='website.altervista.org';
FTP.Username:='website';
FTP.Password:='password';
FTP.Port:=25;
FTP.Connect;
FTP.Put('C:\Users\user\Desktop\text.txt');
FTP.Quit;
end;
I'm not getting any error, but when I start the program and I click on the button, I get an error:
and immediately after another:
and the button disappears.
Why? Thanks!
You have to instantiate the TIdFTP object for your local variable FTP before you access it. So try to use this:
procedure TForm1.Button1Click(Sender: TObject);
var
FTP: TIdFTP;
begin
FTP := TIdFTP.Create(nil);
try
FTP.Host := 'serioussamhd.altervista.org';
FTP.Username := 'serioussamhd';
FTP.Password := 'password';
FTP.Port := 21;
FTP.Connect;
FTP.Put('C:\Users\user\Desktop\text.txt');
FTP.Quit;
finally
FTP.Free;
end;
end;
You must create the instance of the tidftp first.
var
FTP:tidftp;
begin
FTP:=Tidftp.Create(nil); //create the instance
try
FTP.Host:='siteweb.altervista.org';
FTP.Username:='siteweb';
FTP.Password:='password';
FTP.Port:=25;
FTP.Connect;
FTP.Put('C:\Users\user\Desktop\text.txt');
FTP.Quit;
finally
FTP.Free;
end;
end;
I would like to read a text file containing a version number from the Internet resource. Then I need to use this version number within my script.
How to do this in InnoSetup ?
There are many ways how to get a file from the Internet in InnoSetup. You can use an external library like for instance InnoTools Downloader, write your own library, or use one of the Windows COM objects. In the following example I've used the WinHttpRequest COM object for file receiving.
The DownloadFile function in this script returns True, when the WinHTTP functions doesn't raise any exception, False otherwise. The response content of the HTTP GET request to an URL, specified by the AURL parameter is then passed to a declared AResponse parameter. When the script fails the run on exception, AResponse parameter will contain the exception error message:
[Code]
function DownloadFile(const AURL: string; var AResponse: string): Boolean;
var
WinHttpRequest: Variant;
begin
Result := True;
try
WinHttpRequest := CreateOleObject('WinHttp.WinHttpRequest.5.1');
WinHttpRequest.Open('GET', AURL, False);
WinHttpRequest.Send;
AResponse := WinHttpRequest.ResponseText;
except
Result := False;
AResponse := GetExceptionMessage;
end;
end;
procedure InitializeWizard;
var
S: string;
begin
if DownloadFile('http://www.example.com/versioninfo.txt', S) then
MsgBox(S, mbInformation, MB_OK)
else
MsgBox(S, mbError, MB_OK)
end;
I want to download a file from Internet and InternetReadFile seem a good and easy solution at the first glance. Actually, too good to be true. Indeed, digging a bit I have started to see that actually there are a lot of issues with it. People are complaining about all kinds of problems when using this code.
Problems could appear because:
the application freezes temporarily until the HTTP server responds
the application freezes temporarily because the Internet connections breaks
the application locks up because the HTTP server never responds
the InternetOpen (I just discovered this recently) MUST be called only once during application life time
I could not find a complete example about how to use it properly and robustly. Does anybody have an idea about how to implement it in a separate thread and with a time out? There is another SIMPLE way to robustly download a file from Internet. Though I don't want to complicate my life with very large libraries like Jedi or even Indy.
function GetFileHTTP (const fileURL, FileName: String): boolean;
CONST
BufferSize = 1024;
VAR
hSession, hURL: HInternet;
Buffer: array[1..BufferSize] of Byte;
BufferLen: DWORD;
f: File;
sAppName: string;
begin
// result := false;
sAppName := ExtractFileName(Application.ExeName) ;
hSession := InternetOpen(PChar(sAppName), INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0) ; { be aware that InternetOpen need only be called once in your application!!!!!!!!!!!!!! }
TRY
hURL := InternetOpenURL(hSession, PChar(fileURL), nil, 0, 0, 0) ;
TRY
AssignFile(f, FileName) ;
Rewrite(f, 1) ;
REPEAT
InternetReadFile(hURL, #Buffer, SizeOf(Buffer), BufferLen);
BlockWrite(f, Buffer, BufferLen)
UNTIL BufferLen = 0;
CloseFile(f) ;
Result:= True;
FINALLY
InternetCloseHandle(hURL)
end
FINALLY
InternetCloseHandle(hSession)
END;
END;
Edit:
This functions checks if Internet connection is available. It seems to work on Win98 also.
{ Are we connected to the Internet? }
function IsConnectedToInternet: Boolean; { Call SHELL32.DLL for Win < Win98 otherwise call URL.dll }
var InetIsOffline: function(dwFlags: DWORD): BOOL; stdcall;
begin
Result:= FALSE;
if IsApiFunctionAvailable('URL.DLL', 'InetIsOffline', #InetIsOffline)
then Result:= NOT InetIsOffLine(0)
else
if IsApiFunctionAvailable('SHELL32.DLL', 'InetIsOffline', #InetIsOffline)
then Result:= NOT InetIsOffLine(0)
end;
I am using Delphi 7. Many thanks.
Edit:
Losing customers because the application hangs at the first start up is the perfect recipe for losing money.
Writing your code to be Microsoft platform dependent is bad. You never know if the customer has the IE version x.x installed.
Installing stuff into a user's computer is like playing with guns. It will backfire.
(see more about this here: http://thesunstroke.blogspot.com/2010/06/programmig-like-there-is-no-ms-windows.html)
I basically do the same as you do. For me it works fairly flawlessly.
The only differences between my code and your code is I have an INTERNET_FLAG_RELOAD parameter to force a download from the file and not the cache. You can try that and see if it works better:
hURL := InternetOpenURL(hSession, PChar(fileURL), nil, 0, INTERNET_FLAG_RELOAD, 0) ;
Also check for an internet connection before downloading. Do this:
dwConnectionTypes := INTERNET_CONNECTION_MODEM
+ INTERNET_CONNECTION_LAN
+ INTERNET_CONNECTION_PROXY;
InternetConnected := InternetGetConnectedState(#dwConnectionTypes, 0);
if InternetConnected then ...
Here's some sample code that uses Indy. This code is for Delphi 2010 (with Indy 10?), but the code for Delphi 7 would be similar. I've used Indy for years with D7 and have been very happy with it. I think in D7 we use Indy 9. Check if you need to download a new version...
You can use OnWork and OnWorkBegin to add a progress meter if you need to.
This code I excerpted from a bigger piece, editing it a bit. I did not try compiling it, but it will give you a good starting place.
function Download( const aSourceURL: String;
const aDestFileName: String;
out aDownloadResult: TDownloadResult;
out aErrm: String): boolean;
var
Stream: TMemoryStream;
IDAntiFreeze: TIDAntiFreeze;
begin
aDownloadResult := DROther;
Result := FALSE;
fIDHTTP := TIDHTTP.Create;
fIDHTTP.HandleRedirects := TRUE;
fIDHTTP.AllowCookies := FALSE;
fIDHTTP.Request.UserAgent := 'Mozilla/4.0';
fIDHTTP.Request.Connection := 'Keep-Alive';
fIDHTTP.Request.ProxyConnection := 'Keep-Alive';
fIDHTTP.Request.CacheControl := 'no-cache';
IDAntiFreeze := TIDAntiFreeze.Create;
Stream := TMemoryStream.Create;
try
try
fIDHTTP.Get(aSourceURL, Stream);
if FileExists(aDestFileName) then
DeleteFile(PWideChar(aDestFileName));
Stream.SaveToFile(aDestFileName);
Result := TRUE;
aDownloadResult :=drSuccess;
except
On E: Exception do
begin
Result := FALSE;
aErrm := E.Message + ' (' + IntToStr(fIDHTTP.ResponseCode) + ')';
end;
end;
finally
Stream.Free;
IDAntiFreeze.Free;
fIDHTTP.Free;
end;
end; { Download }
My personal favorite is using the WebHttpRequest component from importing the "Microsoft WinHTTP Services" type library: http://yoy.be/item.asp?i142
var
w:IWebHttpRequest;
f:TFileStream;
os:TOleStream;
begin
w:=CoWebHttpRequest.Create;
w.Open('GET',SourceURL,false);
w.Send(EmptyParam);
os:=TOleStream.Create(IUnknown(w.ResponseStream) as IStream);
f:=TFileStream.Create(DestinationFilePath,fmCreate);
os.Position:=0;
f.CopyFrom(os,os.Size);
f.Free;
os.Free;
w:=nil;
end;
I recommend Synapse. It's small, stable and easy-to-use (no need of any external libraries).
Example from httpsend.pas
function HttpGetText(const URL: string; const Response: TStrings): Boolean;
var
HTTP: THTTPSend;
begin
HTTP := THTTPSend.Create;
try
Result := HTTP.HTTPMethod('GET', URL);
if Result then
Response.LoadFromStream(HTTP.Document);
finally
HTTP.Free;
end;
end;
Instead of fiddling with the WinAPI, the ExtActns unit provides just what you need for downloading to a file.
procedure TMainForm.DownloadFile(URL: string; Dest: string);
var
dl: TDownloadURL;
begin
dl := TDownloadURL.Create(self);
try
dl.URL := URL;
dl.FileName := Dest;
dl.ExecuteTarget(nil); //this downloads the file
dl.Free;
except
dl.Free;
end;
end;
Under the hood, it uses URLDownloadToFile from the URLMon library - which is part of IE, and therefore part of Windows.
TDownloadURL doesn't handle any timeout for you - it doesn't look like such a thing is supported in URLMon at all, although there could be some default timeout that causes the call to fail - but you could use the OnProgress event on TDownloadURL to get notified when something happens, and then do something in another thread if it's been too long since the last callback.
Solved using improved version of the above code.
(it still does not solve all issues - MS does not actually implemented full support for server time out)
The connection does not timeout while downloading file from internet