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Full Discussion: Simple Network Program Difficulties
Top Forums Programming Simple Network Program Difficulties Post 17665 by AtleRamsli on Tuesday 19th of March 2002 05:34:51 AM
Old 03-19-2002
I wonder if you speak about two kinds of 'characters' lets say that an array contains

"ABCD" - those are four characters.
If you treat that as an integer you get the number
1145258561, or 0x44434241 - this is probaby what the original poster meant - _converted_ to characters, a number will take more space.
But any sequence of bytes can be seen as anything, char, float, char*, struct foo*,

So, when a network protocol sends 'characters'- you can make those characters mean anything you want, put two together, and you have a 16 bit short, etc.
But beware of how your machine stores integers!
The bytes above may have looked like
"BADC" on some machines to give the same number!
If I am not mistaken, I think the IBM PC is one of them ...

Look at
man htonl
man htons

Then you will understand why it just sends 'characters'- to make it an 'int'you use one of those functions, that puts the bytes in the right 'network'order, and put them back to local 'machine' order.


I often randomize characters with the % operator.

rand() % 10 gives 0-9

rand() % ('z'-'a') + 'a' is also an interesting contruct

Some fun: Remember that characters, int, floats and all that are really just bits.
If you want char is a certain range, maybe you can just chop off some bits!
0123456701234567
1001010011101011
0000111110000000 <- maybe you just want those
-----------------
0000010010000000

This would make it fast by just using one machine op,

AND byte, 000011111
Last edited by AtleRamsli; 03-19-2002 at 07:27 AM..
 

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LEARN ABOUT SUSE

rpcdebug

rpcdebug(8)						      System Manager's Manual						       rpcdebug(8)

NAME

       rpcdebug - set and clear NFS and RPC kernel debug flags

SYNOPSIS

       rpcdebug -vh
       rpcdebug -m module
       rpcdebug -m module -s flags...
       rpcdebug -m module -c flags...

DESCRIPTION

       The  rpcdebug  command  allows an administrator to set and clear the Linux kernel's NFS client and server debug flags.  Setting these flags
       causes the kernel to emit messages to the system log in response to NFS activity; this is typically useful when debugging NFS problems.

       The first form in the synopsis can be used to list all available debug flags.  The second form shows the currently set debug flags for  the
       given module.  The third form sets one or more flags, and the fourth form clears one or more flags.

       The value all may be used to set or clear all the flags for the given module.

OPTIONS

       -c     Clear the given debug flags.

       -h     Print a help message and exit.  When combined with the -v option, also prints the available debug flags.

       -m module
	      Specify which module's flags to set or clear.  Available modules are:

	      nfsd   The NFS server.

	      nfs    The NFS client.

	      nlm    The Network Lock Manager, in either an NFS client or server.

	      rpc    The Remote Procedure Call module, in either an NFS client or server.

       -s     Set the given debug flags.

       -v     Increase the verbosity of rpcdebug's output.

FILES

       /proc/sys/sunrpc/{rpc,nfs,nfsd,nlm}_debug
	      procfs-based interface to kernel debug flags.

SEE ALSO

       rpc.nfsd(8), nfs(5), syslogd(8).

BUGS

       Bugs can be found or reported at http://nfs.sf.net/.

AUTHOR

       Program by Olaf Kirch <okir@suse.de> and <frederic.jolly@bull.ext.net>.	Manpage by Greg Banks <gnb@melbourne.sgi.com>.

								    5 Jul 2006							       rpcdebug(8)
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