5 Dec
2005
5 Dec
'05
2:53 a.m.
Hi Tavis,
I tried your suggestion.
First, thanks for the information about using avp_printf() to save a
pseudo variable to an AVP. Either I overlooked the doc in regard to
this or there isn't any doc. Do you know if it's documented ? Seem to
recall a comment about this on the mailing list a while ago...??
It in my testing, $si = public IP address of the NAT Router which is
what was expected. However, $rd = the private IP of the callee.
Unfortunately the private ip isn't useful. A quick look at the location
table shows that the private IP stored in the "contact" column. It
appears that the value from the "received" column is what is needed. I
guess the question is: "after a lookup(), is the "received" column saved
in a pseudo variable ?
Regards,
Norm
Tavis P wrote:
actually, this would be better
avp_printf("i:401", "$rd");
if ( avp_check("i:401", "eq/$src_ip/g") )
{
xlog("L_INFO", "\"$si\" == \"$rd\"
");
}
Tavis P wrote:
Opps i made a mistake, instead of
"avp_write" you need to use
"avp_printf" to store the pseudo variable into an AVP
and when you are doing the comparison with avp_check you need an alias
defined for the second AVP otherwise you might end up comparing the AVP
with a literal value
modparam( "avpops", "avp_aliases", "dest_ip=i:401"
)
avp_printf("i:400", "$si");
avp_printf("i:401", "$rd");
if ( avp_check("i:400", "eq/$dest_ip/g") )
{
xlog("L_INFO", "\"$si\" == \"$rd\"
");
}
Norman Brandinger wrote:
I agree that the solution that was presented is
BAD for the reasons
stated by both of us and probably more :)
Perhaps using $Ri after the successful lookup() and comparing it to
the $src_ip AVP would work.
The problem was trying to compare a pseudo variable with an AVP.
The doc <snipped below> does not state that pseudo variables can be
used by avp_write().
Pseudo-variables can be used with following modules of OpenSER:
* avpops - function “avp_printf()”
* xlog - functions “xlog()” and “xdbg()”
I did try to use avp_write() to save a pseudo variable to an AVP but
was unsuccessful.
Do you have an example of writing a pseudo variable to an AVP ?
Regards,
Norm
Tavis P wrote:
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Another, more lightweight solution, is:
After a successful lookup(location) you can compare the received IP
address ($si) with the destination domain/ip address returned from the
"lookup" function call ($rd), i think these two pieces of information
are reliable for this purpose
This way you don't have to make extra database calls to determine
locality
Also if you want to compare pseudo variables you can first write them to
an AVP using "avp_write" and then you can make use of "avp_check"
with
data sourced from a pseudo variable
Norman Brandinger wrote:
> I have looked into the problem related to saving saving resources by
> not calling rtpproxy or mediaproxy when both the caller and callee are
> behind the same NAT.
>
> This topic has been discussed many times however, there have been no
> "working" examples, or even partial examples posted (that I'm aware
> of).
>
> Below is a solution to the problem, but is a BAD hack at best.
>
> This solution is BAD because AVP's are added to the usr_preferences
> table during the registration process, but there is no notification
> that a registration has expired and is no longer valid. A cron job
> could be run periodically to delete all received_ip AVP's with no
> matching entry in the location table, but this is another hack to fix
> the first hack.
>
> The solution is BAD because a database calls must be made to save the
> received_ip address into an AVP, then another database call must be
> made to reload the value just so that it can be tested against the
> caller's $src_ip. A pseudo variable $Ri already exists that contains
> the value we use in received_ip, but I have not been able to find a
> way for avp_check() to use $Ri.
>
> The solution is BAD because it will fail when the SIP device(s) are
> behind more than a single NAT router. I believe this is not an issue
> for 95% of the users and 99% of the small office or home users.
>
> I think that a better solution would be to enhance avp_check() to
> accept pseudo variables for the "value" parameter. This would remove
> the need for any database calls.
>
> I'm cross-posting this response to the developers list to bring this
> to their attention and ask for suggestions (it's possible that I've
> totally missed something). If a decision is made to open the avpops
> module to pseudo variables (other than just avp_print()), I would
> suggest the following be looked at:
>
> avp_check() the value parm should accept pseudo variables
> avp_write() the value parm should accept pseudo variables
> avp_pushto() the name parameter should accept pseudo variables
> avp_op() the value parameter should accept pseudo variables
>
> Regards,
> Norm
>
>
> 1) During REGISTER processing, place the following code. I would
> suggest that you put the code "after" all authentication checks and
> "after" the save("location") statement.
>
> # Delete any previously saved IP addressess from the user.
> avp_db_delete("$from/username","s:received_ip");
>
> # Save the source IP address of the user into an AVP called
> received_ip.
> # The saved IP address should be the public address of the NAT router.
> avp_write("$src_ip", "s:received_ip");
>
> # Save the AVP received_ip into the usr_preferences tables associated
> with the user that just registered
> avp_db_store("$from/username","s:received_ip");
>
> 2) During INVITE processing (or wherever you make the decision to use
> or not use rtpproxy / mediaproxy) , place the following code.
>
>
> #---------------------------------------------------------------------------
>
>
> # Are the caller and callee behind the same NAT ?
>
> #---------------------------------------------------------------------------
>
>
> avp_db_load("$to/username", "s:received_ip");
> if (avp_check("s:received_ip", "eq/$src_ip")) {
> setflag(CALLER_AND_CALLEE_ ARE_BEHIND_THE_SAME_NAT);
> };
>
>
>
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