[SOLVED] Invalid argument with fpsetsockopt & SO_RCVTIMEO
lazarus / 38-Networking and Web Programming

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russdirks · 2017-08-01 05:31

I'm using the code below to open a socket for UDP communication, and
set a receive timeout.  The call to fpsetsockopt to set the timeout
works fine for Windows and MacOS, but under Ubuntu, it reports error
22, which I believe is invalid argument.  Anybody have an idea what
the problem could be?

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     // open
the socket   m_socket := fpSocket(AF_INET, SOCK_DGRAM, 0); 
 m_addrIn.sa_family := AF_INET;   m_addrIn.sin_port :=
htons(m_portIn);   m_addrIn.sin_addr.s_addr := INADDR_ANY;   res :=
fpbind(m_socket, @m_addrIn, sizeof(m_addrIn));    ...    // set the
timeout   {$IFDEF Windows}   tv.tv_sec := 100;                       
   // milliseconds   tv.tv_usec := 0;                             //
unused   {$ELSE}   tv.tv_sec := 0;                              //
seconds   tv.tv_usec := 100 * 1000;            // microseconds 
 {$ENDIF}    res := fpsetsockopt(m_socket, SOL_SOCKET, SO_RCVTIMEO,
 @tv, sizeof(tv));

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russdirks · 2017-08-12 05:38

Still stuck on this one.  I was looking at the source code for the
rtl-extra package, and code for fpsetsockopt looks like this:

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 function
 fpsetsockopt  (s:cint; level:cint; optname:cint; optval:pointer;
optlen : tsocklen):cint;begin  fpSetSockOpt:=do_syscall(syscall_nr_Set
SockOpt,S,level,optname,TSysParam(optval),optlen); 
internal_socketerror:=fpgeterrno;end; 
The do_syscall is just a call  to some external code somewhere. 

According to this man page the argument for SO_RCVTIMEO is a struct
timeval.  My tv variable is declared like so:

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 TTimeVal =
record   tv_sec : uint32;   tv_usec : uint32;end;
Anybody have any ideas what the problem might be?

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Thaddy · 2017-08-12 06:08

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 TTimeVal =
packed record   tv_sec : longint;//time_t   tv_usec :
longint;//suseconds_tend;
Note the members are signed members and you need a packed record.
From the man pages https://linux.die.net/man/2/gettimeofday
MSDN https://msdn.microsoft.com/en-
us/library/windows/desktop/ms740560(v=vs.85).aspx

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russdirks · 2017-08-12 15:57

Thanks for responding.  I made those changes, but the error still
persists.

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engkin · 2017-08-12 17:09

I am a Windows person, so I don't know what's wrong with your code
under Linux. But, package fcl-net has DNS query in unit netdb.pp using
fpSelect instead of fpsetsockopt. DNS query, you know, should not wait
forever:

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
...fpsendto(sock,@qry,qrylen+12,0,@SA,SizeOf(SA));  // Wait for
answer.  RTO:=TimeOutS*1000+TimeOutMS;  fpFD_ZERO(ReadFDS); 
fpFD_Set(sock,readfds);  if fpSelect(Sock+1,@readfds,Nil,Nil,RTO)<=0
then    begin    fpclose(Sock);    exit;    end;  AL:=SizeOf(SA); 
L:=fprecvfrom(Sock,@ans,SizeOf(Ans),0,@SA,@AL);  fpclose(Sock);...

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marcov · 2017-08-12 17:17

Maybe linux migrated to a 64-bit timeval ? Do you generate 32-bit or
64-bit applications?

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Thaddy · 2017-08-12 18:17

Quote from: marcov on August 12, 2017, 07:17:12 pmMaybe linux migrated
to a 64-bit timeval ? Do you generate 32-bit or 64-bit applications?
I thought I checked sys/time.h but I will check it again.

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marcov · 2017-08-12 18:22

The best is to compile a small C program that prints sizeof.

Though on Linux that is still open to interpretation, since sometimes
kernel and userland use different structures there.

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russdirks · 2017-08-12 19:54

@marcov I think you were right.  I got it working!  I changed the type
values to PtrInt and now it works.  I'll have to go back to Mac OS X
and Windows to see how it works there.  May have to do some $IFDEFs.

@engkin  Thanks for the sample code.  Based on that and some things I
read in the comments section of this Stack Overflow question, it seems
the fpSelect method with a non-blocking sockets is the better way to
go.