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kamailio/modules/rr/README

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rr Module
Jan Janak
FhG FOKUS
Bogdan-Andrei Iancu
Voice Sistem SRL
Carsten Bock
ng-voice.com
Edited by
Jan Janak
Edited by
Bogdan-Andrei Iancu
Copyright © 2003 FhG FOKUS
Copyright © 2005 Voice Sistem SRL
Copyright © 2011 Carsten Bock, carsten@ng-voice.com
__________________________________________________________________
Table of Contents
1. Admin Guide
1. Overview
2. Dialog support
3. Dependencies
3.1. Kamailio Modules
3.2. External Libraries or Applications
4. Parameters
4.1. enable_full_lr (integer)
4.2. append_fromtag (integer)
4.3. enable_double_rr (integer)
4.4. add_username (integer)
4.5. enable_socket_mismatch_warning (integer)
4.6. custom_user_avp (avp string)
5. Functions
5.1. loose_route()
5.2. record_route() and record_route(string)
5.3. remove_record_route()
5.4. record_route_preset(string [,string2])
5.5. record_route_advertised_address(address)
5.6. add_rr_param(param)
5.7. check_route_param(re)
5.8. is_direction(dir)
6. Exported Pseudo Variables
6.1. $route_uri
2. Developer Guide
1. Available Functions
1.1. record_route(string)
1.2. record_route_advertised_address(string)
1.3. add_rr_param( msg, param)
1.4. check_route_param( msg, re)
1.5. is_direction( msg, dir)
1.6. get_route_param( msg, name, val)
1.7. register_rrcb( callback, param)
2. Examples
List of Examples
1.1. Dialog support in RR module
1.2. Set enable_full_lr parameter
1.3. Set append_fromtag parameter
1.4. Set enable_double_rr parameter
1.5. Set enable_double_rr to 2 to always have two explicit RR headers
1.6. Set add_username parameter
1.7. enable_socket_mismatch_warning usage
1.8. custom_user_avp usage
1.9. loose_route usage
1.10. record_route usage
1.11. remove_record_route usage
1.12. record_route_preset usage
1.13. record_route_advertised_address usage
1.14. add_rr_param usage
1.15. check_route_param usage
1.16. is_direction usage
1.17. $route_uri
2.1. record_route usage
2.2. record_route_advertised_address usage
2.3. Loading RR module's API from another module
Chapter 1. Admin Guide
Table of Contents
1. Overview
2. Dialog support
3. Dependencies
3.1. Kamailio Modules
3.2. External Libraries or Applications
4. Parameters
4.1. enable_full_lr (integer)
4.2. append_fromtag (integer)
4.3. enable_double_rr (integer)
4.4. add_username (integer)
4.5. enable_socket_mismatch_warning (integer)
4.6. custom_user_avp (avp string)
5. Functions
5.1. loose_route()
5.2. record_route() and record_route(string)
5.3. remove_record_route()
5.4. record_route_preset(string [,string2])
5.5. record_route_advertised_address(address)
5.6. add_rr_param(param)
5.7. check_route_param(re)
5.8. is_direction(dir)
6. Exported Pseudo Variables
6.1. $route_uri
1. Overview
The module contains record routing logic
2. Dialog support
Kamailio is basically only a transaction statefull proxy, without any
dialog support build in. There are many features/services which
actually requires a dialog awareness, like storing the information in
the dialog creation stage, information which will be used during the
whole dialog existence.
The most urging example is NAT traversal, in dealing with the within
the dialog INVITEs (re-INVITEs). When processing the initial INVITE,
the proxy detects if the caller or callee is behind some NAT and fixes
the signalling and media parts - since not all the detection mechanism
are available for within the dialog requests (like usrloc), to be able
to fix correspondingly the sequential requests, the proxy must remember
that the original request was NAT processed. There are many other cases
where dialog awareness fixes or helps.
The solution is to store additional dialog-related information in the
routing set (Record-Route/Route headers), headers which show up in all
sequential requests. So any information added to the Record-Route
header will be found (with no direction dependencies) in Route header
(corresponding to the proxy address).
As storage container, the parameters of the Record-Route / Route header
will be used - Record-Route parameters mirroring are reinforced by RFC
3261 (see 12.1.1 UAS behavior).
For this purpose, the modules offers the following functions:
* add_rr_param() - see Section 5.6, “add_rr_param(param)”
* check_route_param() - see Section 5.7, “check_route_param(re)”
Example 1.1. Dialog support in RR module
UAC Kamailio PROXY UAS
---- INVITE ------> record_route() ----- INVITE ---->
add_rr_param(";foo=true")
--- reINVITE -----> loose_route() ---- reINVITE --->
check_route_param(";foo=true")
<-- reINVITE ------ loose_route() <--- reINVITE ----
check_route_param(";foo=true")
<------ BYE ------- loose_route() <----- BYE -------
check_route_param(";foo=true")
3. Dependencies
3.1. Kamailio Modules
3.2. External Libraries or Applications
3.1. Kamailio Modules
The following modules must be loaded before this module:
* (optional) The "outbound" module is needed for outbound routing as
per RFC 5626.
3.2. External Libraries or Applications
The following libraries or applications must be installed before
running Kamailio with this module loaded:
* None.
4. Parameters
4.1. enable_full_lr (integer)
4.2. append_fromtag (integer)
4.3. enable_double_rr (integer)
4.4. add_username (integer)
4.5. enable_socket_mismatch_warning (integer)
4.6. custom_user_avp (avp string)
4.1. enable_full_lr (integer)
If set to 1 then “;lr=on” instead of just “;lr” will be used. This is
to overcome problems with broken UAs which strip “;lr” parameter when
generating Route header fields from Record-Route (“;lr=on” seems to
help).
Default value is 0 (no).
Example 1.2. Set enable_full_lr parameter
...
modparam("rr", "enable_full_lr", 1)
...
4.2. append_fromtag (integer)
If turned on, request's from-tag is appended to record-route; that's
useful for understanding whether subsequent requests (such as BYE) come
from caller (route's from-tag==BYE's from-tag) or callee (route's
from-tag==BYE's to-tag)
Default value is 1 (yes).
Example 1.3. Set append_fromtag parameter
...
modparam("rr", "append_fromtag", 0)
...
4.3. enable_double_rr (integer)
There are some situations when the server needs to insert two
Record-Route header fields instead of one. For example when using two
disconnected networks or doing cross-protocol forwarding from UDP->TCP.
This parameter enables inserting of 2 Record-Routes. The server will
later remove both of them.
Double record-routing does not occur when outbound is used for a
request.
Default value is 1 (yes).
Example 1.4. Set enable_double_rr parameter
...
modparam("rr", "enable_double_rr", 0)
...
Some useragents (e. g. Linphone) incorrectly use UDP transport for
subsequent requests in dialog, despite being configured to use another
SIP transport protocol. This can be worked around by setting
Record-Route header with explicit transport attribute. But
enable_double_rr enabled in default mode omits transport attribute from
being added to header if it detects that both sender and receiver use
same protocol (e. g. TCP or TLS), and this results in UDP being used by
such broken clients. Set enable_double_rr to value 2 to always have two
RR headers with transport attributes expicitly set.
Example 1.5. Set enable_double_rr to 2 to always have two explicit RR
headers
...
modparam("rr", "enable_double_rr", 2)
...
4.4. add_username (integer)
If set to a non 0 value (which means yes), the username part will be
also added in the Record-Route URI.
This option cannot be set when the “outbound” module is loaded before
this module as outbound uses the username part of Record-Route URIs to
store flow-tokens.
Default value is 0 (no).
Example 1.6. Set add_username parameter
...
modparam("rr", "add_username", 1)
...
4.5. enable_socket_mismatch_warning (integer)
When a preset record-route header is forced in Kamailio config and the
host from the record-route header is not the same as the host server, a
warning will be printed out in the logs. The
'enable_socket_mismatch_warning' parameter enables or disables the
warning. When Kamailio is behind a NATed firewall, we don't want this
warning to be printed for every bridged call.
Default value is 1 (yes).
Example 1.7. enable_socket_mismatch_warning usage
...
modparam("rr", "enable_socket_mismatch_warning", 0)
...
4.6. custom_user_avp (avp string)
When enable_username is enabled, a call to record_route will add the
username of the RequestURI to the Record-Route URI. This parameter
allows you to setup an AVP with which you can customise the username to
be added in the Record-Route URI.
Default value: if not set, the std add_username behaviour is used -
i.e. Request URI username.
Example 1.8. custom_user_avp usage
...
modparam("rr", "custom_user_avp", "$avp(RR_CUSTOMER_USER_AVP)")
#usage in cfg file
$avp(RR_CUSTOM_USER_AVP)="mo";
record_route();
...
5. Functions
5.1. loose_route()
5.2. record_route() and record_route(string)
5.3. remove_record_route()
5.4. record_route_preset(string [,string2])
5.5. record_route_advertised_address(address)
5.6. add_rr_param(param)
5.7. check_route_param(re)
5.8. is_direction(dir)
5.1. loose_route()
The function performs routing of SIP requests which contain a route
set. The name is a little bit confusing, as this function also routes
requests which are in the “strict router” format.
This function is usually used to route in-dialog requests (like ACK,
BYE, reINVITE). Nevertheless also out-of-dialog requests can have a
“pre-loaded route set” and my be routed with loose_route. It also takes
care of translating between strict-routers and loose-router.
The loose_route function analyzes the Route: headers in the requests.
If there is no Route: header, the function returns FALSE and routing
should be done with normal lookup functions. If a Route: header is
found, the function returns 1 and behaves as described in section 16.12
of RFC 3261. There is only one exception: If the request is
out-of-dialog (no to-tag) and there is only one Route: header
indicating the local proxy, then the Route: header is removed and the
function returns FALSE.
When the “outbound” module was loaded before this module and the Route:
header contains a username part this function will attempt to use the
username part as a flow-token for routing. If route calculation based
on flow-token succeeds, function returns TRUE even if there is only one
Route: header indicating the local proxy.
Make sure your loose_routing function can't be used by attackers to
bypass proxy authorization.
The loose_routing topic is very complex. See the RFC3261 for more
details (grep for “route set” is a good starting point in this
comprehensive RFC).
Return codes:
* 1 - route calculation has been successful
* 2 - route calculation based on flow-token has been successful
* -1 - route calculation has been unsuccessful
* -2 - outbound flow-token shows evidence of tampering
This function can be used from REQUEST_ROUTE.
Example 1.9. loose_route usage
...
loose_route();
...
5.2. record_route() and record_route(string)
The function adds a new Record-Route header field. The header field
will be inserted in the message before any other Record-Route header
fields.
If any string is passed as parameter, it will be appended as URI
parameter to the Record-Route header. The string must follow the
“;name=value” scheme and it may contain pseudo-variables.
When the “outbound” module was loaded before this module this function
will determine whether outbound is required for the request and
generate and add a flow-token as the username part of the
Record-Route-URI.
This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and
FAILURE_ROUTE.
Example 1.10. record_route usage
...
record_route();
...
5.3. remove_record_route()
The function removes the internal lumps added by record_route()
functions.
Can be used to revert adding Record-Route header(s).
This function can be used from REQUEST_ROUTE and FAILURE_ROUTE.
Example 1.11. remove_record_route usage
...
remove_record_route();
...
5.4. record_route_preset(string [,string2])
This function will put the string into Record-Route, don't use unless
you know what you are doing.
Meaning of the parameters is as follows:
* string - String to be inserted into the first header field; it may
contain pseudo-variables.
* string2 - String to be inserted into the second header field; it
may contain pseudo-variables.
Note: If 'string2' is present, then the 'string' param is pointing to
the outbound interface and the 'string2' param is pointing to the
inbound interface.
When the “outbound” module was loaded before this module this function
will determine whether outbound is required for the request and
generate and add a flow-token as the username part of the
Record-Route-URI.
This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and
FAILURE_ROUTE.
Example 1.12. record_route_preset usage
...
record_route_preset("1.2.3.4:5090");
...
5.5. record_route_advertised_address(address)
The function adds a new Record-Route header field using the address
given. The header field will be inserted in the message before any
other Record-Route header fields.
When the “outbound” module was loaded before this module this function
will determine whether outbound is required for the request and
generate and add a flow-token as the username part of the
Record-Route-URI.
Meaning of the parameter is as follows:
* address - Advertised address to use in the header; it may contain
pseudo-variables.
If double record-routing is enabled two Record-Route headers will be
inserted with the same given address with different transports if the
transport changes.
This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and
FAILURE_ROUTE.
Example 1.13. record_route_advertised_address usage
...
record_route_advertised_address("1.2.3.4:5080");
...
5.6. add_rr_param(param)
Adds a parameter to the Record-Route URI (param must be in
“;name=value” format. The function may be called also before or after
the record_route() or record_route_advertised_address() calls (see
Section 5.2, “record_route() and record_route(string)” or Section 5.5,
“record_route_advertised_address(address)”)).
Meaning of the parameters is as follows:
* param - String containing the URI parameter to be added. It must
follow the “;name=value” scheme; it may contain pseudo-variables.
This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and
FAILURE_ROUTE.
Example 1.14. add_rr_param usage
...
add_rr_param(";nat=yes");
...
5.7. check_route_param(re)
The function checks if the URI parameters of the local Route header
(corresponding to the local server) matches the given regular
expression. It must be call after loose_route() (see Section 5.1,
“loose_route()”).
Meaning of the parameters is as follows:
* re - regular expression to check against the Route URI parameters.
This function can be used from REQUEST_ROUTE.
Example 1.15. check_route_param usage
...
if (check_route_param("nat=yes")) {
setflag(6);
}
...
5.8. is_direction(dir)
The function checks the flow direction of in-dialog requests. This
function uses the “ftag” prameter from the Route header, therefore the
append_fromtag (see Section 4.2, “append_fromtag (integer)” module
parameter must be enabled. Also this must be called only after
loose_route() (see Section 5.1, “loose_route()”).
The function returns true if the “dir” is the same with the request's
flow direction.
The “downstream” direction means that the request is in the same
direction as the initial request that created the dialog.
Meaning of the parameters is as follows:
* dir - string containing the direction to be checked. It may be
“upstream” (from callee to caller) or “downstream” (caller to
callee).
This function can be used from REQUEST_ROUTE.
Example 1.16. is_direction usage
...
if (is_direction("downstream")) {
xdbg("in-dialog request from caller to callee (downstream) ($rm)\n");
} else {
xdbg("in-dialog request from callee to caller (upstream) ($rm)\n");
}
...
6. Exported Pseudo Variables
6.1. $route_uri
6.1. $route_uri
Returns the URI of the top route-header.
Example 1.17. $route_uri
...
xdbg("Route-URI is: $route_uri\n");
...
Chapter 2. Developer Guide
Table of Contents
1. Available Functions
1.1. record_route(string)
1.2. record_route_advertised_address(string)
1.3. add_rr_param( msg, param)
1.4. check_route_param( msg, re)
1.5. is_direction( msg, dir)
1.6. get_route_param( msg, name, val)
1.7. register_rrcb( callback, param)
2. Examples
The RR module provides an internal API to be used by other Kamailio
modules. The API offers support for SIP dialog based functionalities -
for more about the dialog support offered by RR module, see Section 2,
“Dialog support”.
For internal(non-script) usage, the RR module offers to other module
the possibility to register callback functions to be executed each time
a local Route header is processed. The callback function will receive
as parameter the register parameter and the Route header parameter
string.
1. Available Functions
1.1. record_route(string)
1.2. record_route_advertised_address(string)
1.3. add_rr_param( msg, param)
1.4. check_route_param( msg, re)
1.5. is_direction( msg, dir)
1.6. get_route_param( msg, name, val)
1.7. register_rrcb( callback, param)
1.1. record_route(string)
The function adds a new Record-Route header field. The header field
will be inserted in the message before any other Record-Route header
fields.
If any string is passed as parameter, it will be appended as URI
parameter to the Record-Route header. The string must follow the
“;name=value” scheme and it may contain pseudo-variables.
This function can be used from REQUEST_ROUTE, BRANCH_ROUTE and
FAILURE_ROUTE.
Example 2.1. record_route usage
...
record_route();
...
1.2. record_route_advertised_address(string)
This function will add the string into a new Record-Route header field.
Don't use unless you know what you are doing. The header field will be
inserted in the message before any other Record-Route header fields.
Meaning of the parameters is as follows:
* string - String to be inserted into the header field.
Calls to add_rr_param() will add parameters to the Record-Route header.
Note: A second Record-Route will be inserted if the transport used on
the inbound and outbound interfaces changes.
Example 2.2. record_route_advertised_address usage
...
record_route_advertised_address("1.2.3.4:5090");
...
1.3. add_rr_param( msg, param)
Adds a parameter to the requests's Record-Route URI (param must be in
“;name=value” format).
The function returns 0 on success. Otherwise, -1 is returned.
Meaning of the parameters is as follows:
* struct sip_msg* msg - request that will has the parameter “param”
added to its Record-Route header.
* str* param - parameter to be added to the Record-Route header - it
must be in “;name=value” format.
1.4. check_route_param( msg, re)
The function checks for the request “msg” if the URI parameters of the
local Route header (corresponding to the local server) matches the
given regular expression “re”. It must be call after the loose_route
was done.
The function returns 0 on success. Otherwise, -1 is returned.
Meaning of the parameters is as follows:
* struct sip_msg* msg - request that will has the Route header
parameters checked.
* regex_t* param - compiled regular expression to be checked against
the Route header parameters.
1.5. is_direction( msg, dir)
The function checks the flow direction of the request “msg”. As for
checking it's used the “ftag” Route header parameter, the
append_fromtag (see Section 4.2, “append_fromtag (integer)” module
parameter must be enables. Also this must be call only after the
loose_route is done.
The function returns 0 if the “dir” is the same with the request's flow
direction. Otherwise, -1 is returned.
Meaning of the parameters is as follows:
* struct sip_msg* msg - request that will have the direction checked.
* int dir - direction to be checked against. It may be
“RR_FLOW_UPSTREAM” or “RR_FLOW_DOWNSTREAM”.
1.6. get_route_param( msg, name, val)
The function search in to the “msg”'s Route header parameters the
parameter called “name” and returns its value into “val”. It must be
call only after the loose_route is done.
The function returns 0 if parameter was found (even if it has no
value). Otherwise, -1 is returned.
Meaning of the parameters is as follows:
* struct sip_msg* msg - request that will have the Route header
parameter searched.
* str *name - contains the Route header parameter to be serached.
* str *val - returns the value of the searched Route header parameter
if found. It might be empty string if the parameter had no value.
1.7. register_rrcb( callback, param)
The function register a new callback (along with its parameter). The
callback will be called when a loose route will be performed for the
local address.
The function returns 0 on success. Otherwise, -1 is returned.
Meaning of the parameters is as follows:
* rr_cb_t callback - callback function to be registered.
* void *param - parameter to be passed to the callback function.
2. Examples
Example 2.3. Loading RR module's API from another module
...
#include "../rr/api.h"
...
struct rr_binds my_rrb;
...
...
/* load the RR API */
if (load_rr_api( &my_rrb )!=0) {
LM_ERR("can't load RR API\n");
goto error;
}
...
...
/* register a RR callback */
if (my_rrb.register_rrcb(my_callback,0))!=0) {
LM_ERR("can't register RR callback\n");
goto error;
}
...