Re: NSE crash in socket_lock when connect used in prerule

[Daniel Miller <bonsaiviking () gmail com>]

On 03/28/2014 12:23 PM, Patrick Donnelly wrote:
> On Mar 26, 2014 9:21 PM, "David Fifield" <david () bamsoftware com> wrote:
> > The crash is in the last lua_rawset call in socket_lock. I suppose it
> > has something to do with there not existing a script thread at the time
> > the prerule is called. It seems like you should be able to use a socket
> > in a prerule, though. Is there a good fix for this?
> Early on I (?) decided to not allow socket connections in rule functions.
> The reason for that is NSE isn't structured to loop over rule functions
> which have made connections. That is, if a rule function yields, then NSE
> must resume it when the socket operation is complete and get the rule
> function result. I think rule functions need to be short and simple or
> every script is blocked in the rule evaluation step.
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I agree philosophically that rule functions should not be contacting the 
target (or anything else, really). It is fairly simple (and several 
scripts do so) to perform a connection check at the beginning of the 
action and bail (return nil) if there is no way to continue.

However, I think maybe we could be clearer about what is going wrong. Is 
there some state in the Lua environment that could be checked in 
l_connect or socket_lock or somewhere to print a reminder ("Socket 
operations not allowed in rule functions") when this happens?

Dan
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