Where communities thrive


  • Join over 1.5M+ people
  • Join over 100K+ communities
  • Free without limits
  • Create your own community
People
Repo info
Activity
  • Nov 14 18:08
    wqmeng commented #201
  • Nov 14 18:04
    arvanus commented #201
  • Nov 14 17:43
    wqmeng commented #201
  • Nov 14 17:37
    arvanus commented #201
  • Nov 14 17:31
    wqmeng commented #201
  • Nov 14 12:00
    arvanus commented #201
  • Nov 14 09:07
    wqmeng commented #201
  • Nov 14 09:05
    wqmeng commented #201
  • Oct 30 16:15
    rlebeau edited #260
  • Oct 16 04:22
    rlebeau labeled #269
  • Oct 16 04:22
    rlebeau opened #269
  • Oct 08 19:00

    Fulgan on Restructure

    Bug fix for a typo in TIdIMAP4.… (compare)

  • Oct 08 19:00

    Fulgan on master

    Bug fix for a typo in TIdIMAP4.… (compare)

  • Oct 02 21:00

    Fulgan on Restructure

    Updating TIdIMAP4's InternalSea… (compare)

  • Oct 02 21:00

    Fulgan on master

    Updating TIdIMAP4's InternalSea… (compare)

  • Sep 20 21:50

    Fulgan on master

    Embarcadero patch for race cond… (compare)

  • Sep 20 21:50

    Fulgan on Restructure

    Embarcadero patch for race cond… (compare)

  • Sep 10 18:50
    rlebeau closed #268
  • Sep 10 18:50
    rlebeau commented #268
  • Sep 10 18:50

    Fulgan on Restructure

    Fix for TIdResponseHeaderInfo.S… (compare)

mercedwang
@mercedwang
I have created a Linux console app by using TIdTCPServer in Delphi 10.2 Tokyo. I found that the action of setting the Active property of the component to False costs a long time (about half an hour) if the TCP server socket has one or more active connections. However the server socket can be closed quickly if it has no connection. What's the matter?
Matthijs ter Woord
@mterwoord
probably its waiting for connectinos to be terminateds
mercedwang
@mercedwang
@mterwoord However the same code runs very smoothly in Windows platform
mercedwang
@mercedwang
@mterwoord In the OnExecute event handler, I only call AContext.Connection.IOHandler.ReadBytes() to read a byte from the client. After one or more connections have been established, those connections are terminated and TCP server socket are closed very quickly on Windows platform. if the Active property is set to False. However the main thread is frozen for al long time on Linux if the same operation is executed.
Matthijs ter Woord
@mterwoord
no clue. never used indy on linux
well, that is, last 15 years..
mercedwang
@mercedwang
@mterwoord Thanks anyway. How to report this problem to the Indy team?
Matthijs ter Woord
@mterwoord
wait till someone responds here.. :)
Remy Lebeau
@rlebeau
@mercedwang Indy uses blocking sockets, and infinite timeouts by default. When the server is deactivating, it closes all of its active sockets. Closing a socket in one thread is not guaranteed to unblock any blocked socket operations in other threads. It does on Windows, but it may not on all platforms. Try setting the IOHandler.ReadTimeout property to a short timeout and then handle any EIdReadTimedOut errors that occur. Or, before calling IOHandler.ReadBytes() (why not ReadByte()?), you can check IOHandler.InputBufferIsEmptyand if True then call IOHandler.CheckForDataOnSource() with a timeout, and skip ReadByte(s) until the IOHandler.InputBuffer actually has something available to read.
Kudzu
@czhower
Iirc it should unblock when closed from other thread and its defined and expected behavior across platforms.
Remy Lebeau
@rlebeau
@czhower I've seen reports from time to time where a blocking socket operation in one thread is not unblocked when the socket is closed from another thread. Indy is currently coded to expect it to always work on all platforms, but it doesn't always work on all platforms.
Kudzu
@czhower
Ive only ever seen it as a bug in some os patched. Check orig socket docs and I believe it is documented. Lots of software depends on this, especially on *nix.
mercedwang
@mercedwang
@rlebeau I follow ur suggests and implement my own ReadBytes procedure. Now it works very well.
procedure ReadBytes(IOHandler: TIdIOHandler; var VBuffer: TIdBytes; AByteCount: Integer; AAppend: Boolean = True);
const
CheckInterval = 5000;
var
InitialTimeout, Timeout: Integer;
NewDataAvail: Boolean;
begin
Assert(Assigned(IOHandler.InputBuffer));
InitialTimeout := IfThen(IOHandler.ReadTimeout >= 0, IOHandler.ReadTimeout, MaxInt);
while IOHandler.InputBuffer.Size < AByteCount do begin
Timeout := InitialTimeout;
repeat
if Timeout <= 0 then raise EIdReadTimeout.Create(RSReadTimeout);
NewDataAvail := IOHandler.CheckForDataOnSource(Min(CheckInterval, Timeout));
IOHandler.CheckForDisconnect(True, True);
Dec(Timeout, CheckInterval);
until NewDataAvail;
end;
IOHandler.InputBuffer.ExtractToBytes(VBuffer, AByteCount, AAppend);
end;
Kudzu
@czhower
I did some digging, and it looks like there is a bug affecting you. *nix does conform and closing a socket from one thread will err out recv/send calls in other threads.
Some users have reported that some linux builds are not doing this, but its incorrect behaviour and can break lots of apps.
It seems to be a recurring problem on Linux from what I can see.
mercedwang
@mercedwang
@czhower Thank u. Before the closing behaiours become consistent among different Linux distributions, I'd like to use the code above to workaround this problem.
mercedwang
@mercedwang
Another problem. It seems that most recent Linux distributions allow binding IPv4 and IPv6 on the same port concurrently. Will the implementation of adding bindings in TIdCustomTCPServer.Startup become more flexible in the future?
Remy Lebeau
@rlebeau
@mercedwang I don't see how your ReadBytes() implementation is much better than the current TIdIOHandler.ReadBytes() implementation. If you set a non-inifinite positive ReadTimeout, an EIdReadTimeout should already be getting raised by TIdIOHandler.ReadBytes() if no data arrives in the specified time period. Otherwise it blocks indefinately waiting for data (well, Indy actually blocks indefinately, yours unblocks after 24 days). All you are really doing is creating a similar loop to the one that already exists in TIdIOHandler.ReadFromSource(), except that you are forcing the loop to wake up every 5 seconds, whereas Indy lets the OS decide when to wake up. As for the Bindings collection, how much more flexible do you want it to be? It already allow you to bind IPv4 and IPv6 sockets concurrently on the same port, if that is supported by the OS. TIdCustomTCPServer.Startup() simply adds default listening sockets if you don't specify your own bindings beforehand. If you want more control, just setup the Bindings collection yourself how you want before activating the server
mercedwang
@mercedwang
The 5-second loop is to ensure that the TCPServer will complete the Shutdown procedure in a few seconds if I set Active to False on Linux. It also fulfill the large ReadTimeout (e.g. 20 min) requirement.
mercedwang
@mercedwang
It seems that the current implementation only add IPv4 binding automatically on Linux. Because adding both v4 and v6 bindings manually is quite easy, now I think the implementation need not changing. :smile:
Remy Lebeau
@rlebeau
@mercedwang As Chad stated, closing a socket in one thread should be aborting blocked socket operations in other threads. There should be no need for such a 5-sec loop during shutdown. If the socket is waiting for bytes, the closure will abort the wait with an error, causing the reading thread to terminate (unless it doesn't handle the error correctly). As for the Bindings, read the comment above Startup(): "Linux/Unix does not allow an IPv4 socket and an IPv6 socket to listen on the same port at the same time! Windows does not have that problem..." At the time that comment was written, that behavior was tested and verified as not working. Has that changed? It certainly doesn't work on Android, which runs on top of Linux. Listening on the same port with both IPv4 and IPv6 usually requires a dual-stack socket, which Indy doesn't support yet (IndySockets/Indy#29). However, Linux has a config option (/proc/sys/net/ipv6/bindv6only) that can automatically bind an IPv4 port when binding an IPv6 port without needing separate sockets or the IPV6_V6ONLY option enabled explicitly in code.
mercedwang
@mercedwang
As you know, some Linux distributions with defects do not abort blocked socket operations, so I have to workaround this problem.
mercedwang
@mercedwang
I remember both IPv4 and v6 bindings will be added automatically on Windows when TIdTCPServer.Startup is executed, and it can accept connections of both v4 and v6 TCP clients. Doesn't it support dual stack?
mercedwang
@mercedwang
In recent Linux distributions, netstat shows that sshd binds both v4 and v6 on port 22, and Embarcadero's PAServer binds both v4 and v6 on 64211.
Remy Lebeau
@rlebeau
@mercedwang Embarcadero uses Indy in PAServer. In fact, it was Embarcadero that first alerted me to the problem of not being able to bind separate IPv4 and IPv6 sockets to the same port on Linux (when they were working on adding Linux to Delphi), leading to the current implementation in Indy to disable that logic. But like I said, Linux has an option to auto-bind an IPv4 port when binding an IPv6 port, so you might be seeing that behavior at play
mercedwang
@mercedwang
@czhower I have done a lot of tests on various newest Linux distributions. If this is a bug truly, it is too usual. It occurs in all Linux platforms I tested including but not limited to: Ubuntu 16.04, Ubuntu 17.10, Fedora 27, CentOS 1708, open SUSE 42.3, Oracle Linux 7.4
Kudzu
@czhower
From my reading it appears to be a persistent and accepted behaviour in modern Linux. There are work arounds, but they are basically breaking tons of *nix code well beyond Indy that has had to be adjusted.
mercedwang
@mercedwang
@czhower I see. Thanks
Kudzu
@czhower
Remy - maybe we need to apply some fixes to work around this non standard beahvour Linux is adopting?
Remy Lebeau
@rlebeau
@czhower you mean, when Linux doesn't abort blocked operations when the socket is closed from another thread? That might be pretty hard to work around without going to non-blocking sockets, or using internal timeout loops on blocking operations.
Kudzu
@czhower
In modern Linux distros it apears so - but there are some work around we can apply into the code. Linux appears to have gained dementia and like typical C++ devs they are now apparently calling it a feature rather than a bug that it is - the original socket specs AFAIR are very clear on this and I know other POSIX and *nix distros are.
Ill lok for the ones I read before, but it loks like not just close but shutdown ash to be called.
I cant find the thread.. but basically it seems sometime around 2006 (post Kylix..) Linux started this new behavior and its now become "accepted" although its broken according to socket specs.
I cant tell how widespread it is, but its widespread enough to be in google a lot.
Kudzu
@czhower
I think we had even under Kylix days to do a small tweak for connecting, but connecting only... I dont remember though as its been about 15 years.
"Calling shutdown() before close() seems to cause the sync Receive to return 0 bytes (i.e. EOF)."
dotnet/corefx#22564
Thats the thread I was looking for
"FYI, for sync Send the behavior is similar: without shutdown it hangs, with shutdown it returns EINVAL -- presumably because the socket is no longer valid for sending."
so probably a simple fix.
Remy Lebeau
@rlebeau
@czhower TIdSocketHandle.CloseSocket() calls TIdStack.Disconnect(), and all of the TIdStack... classes (except TIdStackDotNet) call shutdown() before close(socket)() inside of their Disconnect().
Kudzu
@czhower
hmm.. someone needs to check it on Linux then....
rkmanaz
@rkmanaz

found a bug in IdSSLOpenSSL.pas
procedure DumpCert(AOut: TStrings; AX509: PX509);

->
BIO_get_mem_data( LMem, LBufPtr);
if (LLen > 0) and Assigned(LBufPtr) then begin

BIO_get_mem_data expects pointer to pointer
fixed code;
'
var
LMem: PBIO;
LLen : TIdC_INT;
LBufPtr : Pointer;
lPBPtr : Pointer;
begin
if Assigned(X509_print) then begin
LMem := BIO_new(BIO_s_mem);
try
lPBPtr := @LBufPtr;
X509_print(LMem, AX509);
LLen := BIO_get_mem_data( LMem, lPBPtr);

  if (LLen > 0) and Assigned(LBufPtr) then begin

'

mercedwang
@mercedwang
Found a few type errors in IdSSLOpenSSLHeaders.pas:
In definitions of EVP_DecryptUpdate, EVP_DecryptFinal, EVP_DecryptFinal_ex, EVP_CipherUpdate and EVP_OpenFinal, the type of outl parameter should not be TIdC_INT, but PIdC_INT.
The next_proto_select_cb function pointer field in the definition of SSL_CTX record: Its definition should be either 'outlen : PIdAnsiChar' or 'out outlen: TIdAnsiChar' .
Remy Lebeau
@rlebeau
@rkmanaz the original DumpCert code is fine. Look at the declaration of BIO_get_mem_data() in IdSSLOpenSSLHeaders.pas: function BIO_get_mem_data(b : PBIO; out pp : Pointer) : TIdC_INT; In Delphi, out: Pointer is equivilent to void** in C. The original code was already passing a pointer-to-pointer. Your change is passing a pointer-to-pointer-to-pointer instead
Remy Lebeau
@rlebeau
@mercedwang I don't have time right now to review everything you have pointed out, I'll do it tomorrow
rkmanaz
@rkmanaz
@rlebeau point beeing, the dumpcert function does not work, aka it never prints anything, because Assigned(LBufPtr) is always false.