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plugin.c: register_handoff gets overwritten to NULL for custom plugin

asked 2018-06-14 08:18:08 +0000

MSK gravatar image

updated 2018-06-14 08:58:27 +0000

Jaap gravatar image

Hello,

I have written a custom dissector on the latest version of Wireshark running on the Ubuntu GNU/Linux OS. I can see the protocol being registered with Wireshark but have a problem with dissecting the packets for my protocol. In the plugin.c file for my plugin, the register_handoff is always NULL and when I assign to my protocol hand_off and build it and on running I am able to see my protocol being dissected for a few seconds, after which Wireshark gets terminated with error: stack smashing detected ***; <unknown> terminated.

When Wireshark is build again, the register_handoff gets assigned to NULL again, after which I cannot dissect packets. Now, this overwrite does not happen when registering the protocol. Happens only for the reg_handoff part.

Please advice.

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Stop referring to this as a 'problem in capturing the packets for my protocol'. You have problems dissecting the packets of your protocol. Edited accordingly.

Jaap gravatar imageJaap ( 2018-06-14 08:58:29 +0000 )edit

Without any code to look at, I would suggest that you try reviewing the README.plugins file, and a sample plugin such as gryphon to help you resolve your problem.

cmaynard gravatar imagecmaynard ( 2018-06-14 14:12:18 +0000 )edit

I think the issue is that in the make-plugin-reg.py the symbol for my plugin is not in the regs['handoff_reg'] so it sets the reg_code for the register_handoff to NULL. I understand make-plugin-reg.py automatically generates the plugin.c files so I was wondering where exactly does it gets all the settings from ?

Really appreciate if someone could guide me. Thanks in advance.

MSK gravatar imageMSK ( 2018-06-20 01:08:07 +0000 )edit

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answered 2018-06-20 05:53:37 +0000

Jaap gravatar image

You dissector must have two registration functions formatted as this (as defined in doc/packet-PROTOABBREV.c):

/* Prototypes */
/* (Required to prevent [-Wmissing-prototypes] warnings */
void proto_reg_handoff_PROTOABBREV(void);
void proto_register_PROTOABBREV(void);

....

void
proto_register_PROTOABBREV(void)
{
....
}

void
proto_reg_handoff_PROTOABBREV(void)
{
....
}

If you deviate from this specific format, the registration routines will not be detected in the build, hence not called, and your dissector will not work.

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Asked: 2018-06-14 08:18:08 +0000

Seen: 255 times

Last updated: Jun 20 '18