[asterisk-dev] unexpected behavior between chan_sip and chan_iax2 configuration files

[Olle E. Johansson]

8 sep 2011 kl. 01:02 skrev Paul Belanger:

> On 11-09-03 05:47 PM, Tilghman Lesher wrote:
>> On Saturday, September 03, 2011 12:58:57 PM Paul Belanger wrote:
>>> Consider the following two configuration files:
>>> 
>>> ---
>>> ; sip.conf
>>> [general]
>>> udpbindaddr = 127.0.0.1:5060
>>> #include "sip.general.conf.inc"
>>> 
>>> ---
>>> ; sip.general.conf.inc
>>> udpbindaddr = 192.168.1.195:5060
>>> 
>>> ---
>>> ; iax.conf
>>> [general]
>>> bindaddr = 127.0.0.1
>>> #include "iax.general.conf.inc"
>>> 
>>> ---
>>> ; iax.general.conf.inc
>>> bindaddr = 192.168.1.195
>>> 
>>> I would expect both to have the same behavior, which chan_sip.c will
>>> bind to 192.168.1.195.  This is because, as I understand, chan_sip
>>> can actually only bind to one interface (due to how it is written).
>>> 
>>> However with chan_iax2, I am seeing something different.  It not only
>>> binds to 192.168.1.195 but it also binds to 127.0.0.1.  It seem with
>>> the bindaddr setting for chan_iax2, it does not override the
>>> previous setting like chan_sip.c.
>>> 
>>> I took a look into chan_iax2 and can see why, as the configuration
>>> setting is read, asterisk binds right away. Where chan_sip, binds
>>> after all the configuration file settings have been read.
>>> 
>>> My question is, does chan_iax2 actually support binding to multiple
>>> interfaces? Making it different then chan_sip or should the binding
>>> happen like chan_sip, after parsing the complete configuration file?
>> 
>> It does, but not in the way that you might expect.  It only supports
>> setting a particular peer's sourceaddress in the peer definition to one
>> of the alternate bind addresses.  If a packet is received on the "wrong"
>> socket, the connection will likely not work correctly, because IAX
>> depends upon receiving a response from the same IP as to which it sent
>> the original packet.
>> 
> Thanks for the information, personally I don't like it but I'll have to live with it.
> 
> However, since I am on the topic of 'overwriting' settings in a configuration file, is the following example in asterisk supported?
> 
> foo.conf
> ---
> bar = yes
> bob = smith
> bar = no
> 
> I would assume bar is 'no', am I correct in thinking this is how configuration files should work?  Excluding the original example with bindaddr and chan_iax2.
> 
> 
This is often confusing people as we teach. It depends on the setting.

Compare with multiple rows of allow/disallow or permit/deny. IAX2 allows multiple context= lines where SIP and other channels does not.

/O