Wireshark-dev: Re: [Wireshark-dev] proto_tree_get_parent()
From: wsgd <[email protected]>
Date: Tue, 30 Mar 2010 21:06:16 +0200
If I well understand the current Wireshark design on this point :

1) the parent of an item is the tree which contains this item
And a tree is an item.
-> proto_item_get_parent

2) the parent of a tree is an item which is the tree itself
proto_item and  proto_tree are both proto_node.
-> proto_tree_get_parent



Olivier


Maynard, Chris a écrit :
... and if we really want to retain a function call for whatever reason, then at the very least it should be renamed to something like proto_tree_cast_tree_to_item() for clarity, since that's all the function does.

- Chris


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Maynard, Chris
Sent: Monday, March 29, 2010 10:21 AM
To: 'Developer support list for Wireshark'
Subject: Re: [Wireshark-dev] proto_tree_get_parent()

I still don't get it.  Compare proto_item_get_parent() with proto_tree_get_parent():

proto_item*
proto_item_get_parent(proto_item *ti) {
        if (!ti)
                return (NULL);
        return ti->parent;
}

proto_item*
proto_tree_get_parent(proto_tree *tree) {
        if (!tree)
                return (NULL);
        return (proto_item*) tree;
}

The former returns a pointer to the parent whereas the latter simply casts the tree to an item.  If a cast is all that's needed, then that can be very easily accomplished without a confusing and misleading function call.

- Chris


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Kukosa, Tomas
Sent: Monday, March 29, 2010 2:26 AM
To: Developer support list for Wireshark
Subject: Re: [Wireshark-dev] proto_tree_get_parent()

Hi, I guess the function works well and as expected.
It returns parent proto_item of the proto_tree and in our internal representation the item and its subtree are the same object only casted either to proto_item or proto_tree.

Regards,
  Tomas


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Maynard, Chris
Sent: Sunday, March 28, 2010 1:46 AM
To: 'Developer support list for Wireshark'
Subject: Re: [Wireshark-dev] proto_tree_get_parent()

This sure looks like a bug to me.  A quick search shows at least these 18 dissectors calling it:
$ grep -l proto_tree_get_parent packet-*.c
packet-amr.c
packet-assa_r3.c
packet-dcerpc.c
packet-h264.c
packet-h450-ros.c
packet-h450.c
packet-h460.c
packet-iax2.c
packet-isakmp.c
packet-mikey.c
packet-mp4ves.c
packet-q931.c
packet-q932-ros.c
packet-qsig.c
packet-rtp.c
packet-smb2.c
packet-ssl.c
packet-tcp.c

If things are working correctly in those dissectors, then I think it's by pure luck and the function call can simply be omitted.  Either way, I think the function should be changed to implement what its proto_item_get_parent() peer implements.  I would suggest filing a bug report about.

Good catch.
- Chris


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Eloy Paris
Sent: Thursday, March 25, 2010 8:49 PM
To: Developer support list for Wireshark
Subject: [Wireshark-dev] proto_tree_get_parent()

Is this right (from epan/proto.c):

proto_item*
proto_tree_get_parent(proto_tree *tree) {
	if (!tree)
		return (NULL);
	return (proto_item*) tree;
}

This basically returns the same thing that is received as a parameter. Shouldn't tree->parent be returned instead, just as proto_item_get_parent() (a few lines above in the same file) does?
The weird thing is that there is code using this seemingly broken 
proto_tree_get_parent(). I don't know how things are working given that 
proto_tree_get_parent() is not really providing the parent node.
Confused,

Eloy Paris.-
netexpect.org
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