Multicast options in WinSock with java

[Mike Hearn]

Hi all,

I have a bit of a problem. Essentially, the problem is that Java 1.4 is
buggy, it includes winsock.h, but then proceeds to use winsock2. That
wouldn't be an issue, except that my app uses multicast sockets, and for
reasons known only to Redmond they decided to change the values of some
of the multicast socket option constants.

Java, therefore, passes in the winsock1 values to winsock2. Windows
apparently can deal with this just fine (well, the appw works), despite
there being no obvious way to remap them, both IP_MULTICAST_IF and
IP_HDRINCL which both == 2 in different winsock versions would be valid
at once on XP/2003 for instance.

Marcus, I know you took a stab at implementing multicast support once,
so if you have any tips that'd be appreciated.

If anybody knows a way you might be able to detect that a program is
using the wrong headers for the winsock2 dll, please let me know.

thanks -mike

[Ove Kaaven]

man, 2003-03-31 kl. 11:38 skrev Mike Hearn:
> Hi all,
>
> I have a bit of a problem. Essentially, the problem is that Java 1.4 is
> buggy, it includes winsock.h, but then proceeds to use winsock2. That
> wouldn't be an issue, except that my app uses multicast sockets, and for
> reasons known only to Redmond they decided to change the values of some
> of the multicast socket option constants.
>
> Java, therefore, passes in the winsock1 values to winsock2. Windows
> apparently can deal with this just fine (well, the appw works), despite
> there being no obvious way to remap them, both IP_MULTICAST_IF and
> IP_HDRINCL which both == 2 in different winsock versions would be valid
> at once on XP/2003 for instance.
>
> Marcus, I know you took a stab at implementing multicast support once,
> so if you have any tips that'd be appreciated.
>
> If anybody knows a way you might be able to detect that a program is
> using the wrong headers for the winsock2 dll, please let me know.

A requested version is given to WSAStartup by the app. What is it?

[Mike Hearn]

> A requested version is given to WSAStartup by the app. What is it?

Yeah, I found that a few minutes ago, but for some reason it seems to be
called twice, the first time with version 2 requested then immediately
afterwards again with version 1. Pretty strange.

I just traced it under XP and there it gives the correct value (9) for
the socket option. I'm staring at the java source and trying to figure
out how it can do that, considering it seems to pass in a constant from
winsock.h, but it must fiddle things somewhere.....