Re: [9fans] [9ans] Question about network protocols

Re: [9fans] [9ans] Question about network protocols

[erik quanstrom]

> 1) as i understand, protocol initialization occurs in ipgetfs, which not used anywhere, except
> ipattach function in same file (devip.c). ipattach, in turn, member of ipdevtab struct and latter
> isn't used anywhere too (i haven't found any with grep).
> It seems me strange, but at this point i assume, theese actions take place at system start up (this
> not true, i think).

on boot, ip will be typically be attached by the boot process.

> 3) with your reference on ipgetfs i'm googled presentation [1], a little explaining to me the
> mechanism of choice.
> name = netmkaddr("133.137.166.17", "udp", "echo");
> netmkaddr takes the text name of protocol and, as i saw in sources, and passes it to fprint, which
> call vfprint, which, in turn, call dofmt. As i understand, dofmt is some internal machinery for
> parse format string and decide to use the appropriate protocol. But I did not see where a
> connection is opened or something like that.
> Is my assumption about fprint and dofmt true?

dofmt is part of the print library.  netmkaddr returns
a cannonical address as a text string.  this address can
be passed to dial(2) to make a connection.

netmkaddr doesn't have any knowledge of specific
protocols.  if you were to add a new connection type
tomorrow, netmkaddr wouldn't need any modification.
dial wouldn't either.

at this point, you should probablly be reading the
man pages for these things.  there on the cd and
online at plan9.bell-labs.com.

- erik

[9fans] Re: [9ans] Question about network protocols

[ty ty]

Thanks!
it becomes more clear for me.  But i still don't undrstand some things.

1) as i understand, protocol initialization occurs in ipgetfs, which not used anywhere, except
ipattach function in same file (devip.c). ipattach, in turn, member of ipdevtab struct and latter
isn't used anywhere too (i haven't found any with grep).
It seems me strange, but at this point i assume, theese actions take place at system start up (this
not true, i think).

2) it remains unclear for me where the connection establish, and where ilconnect or tcpconnect take
place. as i think, they should be called for open connections, working on on of these protocols. i
dont find anything relevant and don't understand, how system choose protocol for some work.

3) with your reference on ipgetfs i'm googled presentation [1], a little explaining to me the
mechanism of choice.
name = netmkaddr("133.137.166.17", "udp", "echo");
netmkaddr takes the text name of protocol and, as i saw in sources, and passes it to fprint, which
call vfprint, which, in turn, call dofmt. As i understand, dofmt is some internal machinery for
parse format string and decide to use the appropriate protocol. But I did not see where a
connection is opened or something like that.
Is my assumption about fprint and dofmt true?
where i can read about internal system processes, which managed network connections?
and where, nevertheless, a connection is opened? :)
Excuse my english and, maybe incomprehensible exposition of ideas, it's deep night in Moscow now :)

Thanks.

[1] -- http://www.tip9ug.jp/meetings/udp-12Nov05/plan9udp.ppt

Re: [9fans] [9ans] Question about network protocols

[matt]

ty ty wrote:

>i haven't found any with grep
>
I find this quite good for browsing the source in a web browser

http://fxr.watson.org/fxr/source/?v=PLAN9

ipattach is referenced here

http://fxr.watson.org/fxr/ident?v=PLAN9;i=ipattach

Re: [9fans] [9ans] Question about network protocols

[erik quanstrom]

On Wed Oct 28 16:44:36 EDT 2009, ash_666@bk.ru wrote:
> Hi, folks.
> I'm trying to understand how system interact with network protocols, such as tcp, udp and other.
> i'm look through sources in /sys/src/9/ip/ and saw follow:
>  - protocol header struct
>  - protocl init function
> and so on.
> But i'm grep in plan9.iso and don't find any files, when Tcp4hdr or tcpinit used. How it could be
> used?
> Where i can read about it or, better, where i can see at code, used such functions.
>
> Sorry for english and maybe foolish question.

excellent question.  you're running into a little magic
built into the kernel build scripts.  port/makedevc
is a script called from the kernel mkfile (these days,
usually pc/mkfile) that builds $kernelconfig.c.  this
file has an array called ipprotoinit.  if you specifiy
tcp in your kernel config, this array will contain a
reference to tcpinit.  here's the array from my kernel

	void (*ipprotoinit[])(Fs*) = {
		ilinit,
		tcpinit,
		udpinit,
		ipifcinit,
		icmpinit,
		icmp6init,
		nil,
	};

this array is referenced in ip/ipgetfs where tcpinit
would typically be called.

i hope that answers the question.  it is a bit confusing.

- erik

[9fans] [9ans] Question about network protocols

[ty ty]

Hi, folks.
I'm trying to understand how system interact with network protocols, such as tcp, udp and other.
i'm look through sources in /sys/src/9/ip/ and saw follow:
 - protocol header struct
 - protocl init function
and so on.
But i'm grep in plan9.iso and don't find any files, when Tcp4hdr or tcpinit used. How it could be
used?
Where i can read about it or, better, where i can see at code, used such functions.

Sorry for english and maybe foolish question.
Thanks.