# &adminguide;

## Overview

### Introduction

Dynamic Routing is a module for selecting (based on multiple criteria) the best gateway/destination to be used for delivering a certain call. Least Cost Routing (LCR) is a special case of dynamic routing - when the rules are ordered based on costs. Dynamic Routing comes with many features regarding routing rule selection:

- prefix based

- caller/group based

- time based

- priority based

, processing :

- stripping and prefixing

- default rules

- inbound and outbound processing

- script route triggering

and failure handling:

- serial forking

- weight based GW selection

- random GW selection

- GW probing for crashes

### Features

The dynamic routing implementation for &osips; is designed with the following properties:

- The routing info (destinations, carriers, rules, groups) is stored in a database and loaded into memory at start up time; reload at runtime via a Management Interface command.

- weight-based or random selection of the destinations (from a rule or from a carrier), failure detection of gateways (with switching to next available gateway).

- able to handle large volume of routing info (10M of rules) with minimal speed/time and memory consumption penalties

- script integration - Pseudo-variable support in functions; scripting route triggering when rules are matched

- bidirectional behavior - inbound and outbound processing (strip and prefixing when sending and receiving from a destination/GW)

- blacklisting - the module allows definition of blacklists based on the destination IPs. This blacklists are to be used to prevent malicious forwarding to GWs (based on DNS lookups) when the script logic does none-GE forwarding (like foreign domains).

- loading routing information from multiple databases - the gateways, rules, groups and carriers can be grouped by partitions, and each partition may be loaded from different databases/tables. This makes the routing process partition based. In order to be able to use a table from a partition, its name must be found in the "version" table belonging to the database defined in the partition's db_url.

### Performance

There were several tests performed regarding the performance of the module when dealing with a large number of routing rules.

The tests were performed with a set of 383000 rules and measured:

- time to load from DB

- used shared memory

The time to load was varying between 4 seconds and 8 seconds, depending of the caching of the DB client - the first load was the slowest (as the DB query hits the disk drive); the following are faster as data is already cached in the DB client. So technically speaking, the time to load (without the time to query which is DB type dependent) is ~4 seconds

After loading the data into shared memory ~ 96M of memory were used exclusively for the DR data.

### Dynamic Routing Concepts

DR engine uses several concepts in order to define how the routing should be done (describing all the dependencies between destinations and routing rules).

#### Destination/Gateways

These are the end SIP entities where actually the traffic needs to be sent after routing. They are stored in a table called dr_gateways. Gateway addresses are stored in a separate table because of the need to access them independent of Dynamic Routing processing (e.g., adding/ removing gateway PRI prefix before/after performing other operation -- receiving/relaying to gateway).

In DR, a gateway is defined by:

- id (string)

- SIP address (SIP URI)

- type (number to allow to group GW based on purpose, like inbound, outbound, etc)

- strip value (number of digits) from dialled number

- prefix (string) to be added to dialled number

- attributes (not used by DR engine, but only pushed to script level when routing to this GW)

- probing mode (how the GW should be probed at SIP level - see the probing chapter)

The Gateways are to be used from the routing rule or from the carrier definition. They are all the time referred by their ID.

#### Carriers

The carrier concept is used if you need to group gateways in order to have a better control on how the GWs will be used by DR rules; like in what order the GWs will be used.

Basically, a carrier is a set of gateways which have its own sorting algorithm and its own attribute string. They are by default defined in the dr_carriers table.

In DR, a carrier is defined by:

- id (string)

- list of gateways with/without weights (string) (Ex:gw1=10,gw4=10 or gw1,gw2

- flags : 0x1 - use weight for sorting the list and not definition order; 0x2 - use only the first gateway from the carrier (depending on the sorting); 0x4 - disable the usage of this carrier

- attributes (not used by DR engine, but only pushed to script level when routing to this carrier)

The Carriers are to be used only from the routing rule definition. They are all the time referred by their ID.

#### Routing Rules

These are the actual rules which control the routing. Using different criterias (prefix, time, priority, etc), they will decide to which gateways the call will be sent.

Default name for the table storing rule definitions is dr_rules.

In DR, a carrier is defined by:

- group (list of numbers) - rules can be grouped (a rule may belong to multiple groups in the same time ) and you can use only a certain group at a point; like having a premium or standard or interstate or intrastate groups of rules to be used in different cases

- prefix (string with digits only) - prefix to be used for matching this rule (longest prefix matching)

- time validity (time recurrence string) - when this rule is valid from time point of view (see RFC 2445)

- priority (number) - priority of the rule - higher value, higher priority (see rule section alg)

- script route ID (string) - if defined, then execute the route with the specified ID when this rule is matched. That's it, a route which can be used to perform custom operations on message. NOTE that no modification is performed at signaling level and you must NOT do any signaling operations in that script route

- list of GWs/carriers (string) - a comma separated list of gateways or carriers (defined by IDs) to be used for this rule; the carrier IDs are prefixed with # sign. For each ID (GW or carrier) you may specify a weight. For how this list will be interpreted (as order) see the rule selection section. Example of list: gw1,gw4,#cr3 or gw1=10,gw4=10,#cr3=80

- attributes (not used by DR engine, but only pushed to script level when this rule matched and been used)

More on time recurrence:

- A date-time expression that defines the time recurrence to be matched for current rule. Time recurrences are based closely on the recurring time intervals from the Internet Calendaring and Scheduling Core Object Specification (calendar COS), RFC 2445. The set of attributes used in routing rule specification is a subset of time recurrence attributes.

- The value stored in database has the format of: <dtstart>|<duration>|<freq>|<until>|<interval>|<byday>|<bymonthday>|<byyearday>|<byweekno>|<bymonth>

- When an attribute is not specified, the corresponding place must be left empty, whenever another attribute that follows in the list has to be specified.

### Routing Rule Processing

The module can be used to find out which is the best gateway to use for new calls terminated to PSTN. The algorithm to select the rule is as follows:

- the module discovers the routing group of the originating user. This step is skipped if a routing group is passed from the script as parameter.

- once the group is known, in the subset of the rules for this group the module looks for the one that matches the destination based on "prefix" column. The set of rules with the longest prefix is chosen. If no digit from the prefix matches, the default rules are used (rules with no prefix)

- within the set of rules is applied the time criteria, and the rule which has the highest priority and matches the time criteria is selected to drive the routing.

- Once found the rule, it may contain a route ID to execute. If a certain flag is set, then the processing is stopped after executing the route block.

- The rule must contain a chain of gateways and carriers. The module will execute serial forking for each address in the chain (ordering is either done by simply using the definition order or it may weight-based - weight selection must be enabled). The next address in chain is used only if the previously has failed.

- With the right gateway address found, the prefix (PRI) of the gateway is added to the request URI and then the request is forwarded.

If no rule is found to match the selection criteria an default action must be taken (e.g., error response sent back). If the gateway in the chain has no prefix the request is forwarded without adding any prefix to the request URI.

### Probing and Disabling destinations

The module has the capability to monitor the status of the destinations by doing SIP probing (sending SIP requests like OPTIONS).

For each destination, you can configure what kind of probing should be done (probe_mode column):

- (0) - no probing at all;

- (1) - probing only when the destination is in disabled mode (disabling via MI command will completely stop the probing also). The destination will be automatically re-enabled when the probing will succeed next time;

- (2) - probing all the time. If disabled, the destination will be automatically re-enabled when the probing will succeed next time;

A destination can become disabled in two ways:

- script detection - by calling from script the dr_disable() function after trying the destination. In this case, if probing mode for the destination is (1) or (2), the destination will be automatically re-enabled when the probing will succeed.
- MI command - by calling the dr_gw_status MI command for disabling (on demand) the destination. If so, the probing and re-enabling of this destination will be completly disabled until you re-enable it again via MI command - this is designed to allow controlled and complete disabling of some destination during maintenance.

## Dependencies

### &osips; Modules

The following modules must be loaded before this module:

- a database module.

- tm module.

### External Libraries or Applications

- none.

## Exported Parameters

### `db_url`(str)

The database url.

Default value is NULL.

#### Set `db_url` parameter

    ...
    modparam("drouting", "db_url",
    	"mysql://opensips:opensipsrw@localhost/opensips")
    ...

### `drd_table`(str)

The name of the db table storing gateway addresses.

Default value is dr_gateways.

#### Set `drd_table` parameter

    ...
    modparam("drouting", "drd_table", "dr_gateways")
    ...

### `drr_table`(str)

The name of the db table storing routing rules.

Default value is dr_rules.

#### Set `drr_table` parameter

    ...
    modparam("drouting", "drr_table", "rules")
    ...

### `drg_table`(str)

The name of the db table storing groups.

Default value is dr_groups.

#### Set `drg_table` parameter

    ...
    modparam("drouting", "drg_table", "groups")
    ...

### `drc_table`(str)

The name of the db table storing definitions of the carriers that will be used directly by the routing rules.

Default value is dr_carriers.

#### Set `drc_table` parameter

    ...
    modparam("drouting", "drc_table", "my_dr_carriers")
    ...

### `ruri_avp` (str)

The name of the avp for storing Request URIs to be later used (alternative destiantions for the current one).

Default value is $avp(___dr_ruri__) if `use_partitions` parameter is 0 or $avp(___dr_ruri__partition_name) where partition_name is the name of the partition containing the AVP (as fetched from the database) if `use_partitions` parameter is 1.

#### Set `ruri_avp` parameter

    ...
    modparam("drouting", "ruri_avp", '$avp(dr_ruri)')
    modparam("drouting", "ruri_avp", '$avp(33)')
    ...

### `gw_id_avp` (str)

The name of the avp for storing the id of the current selected gateway/destination - once a new destination is selected (via the use_next_gw() function), the AVP will be updated with the ID of the new selected gateway/destination.

Default value is $avp(___dr_gw_id__) if `use_partitions` parameter is 0 or $avp(___dr_gw_id__partition_name) where partition_name is the name of the partition containing the AVP (as fetched from the database) if `use_partitions` parameter is 1.

#### Set `gw_id_avp` parameter

    ...
    modparam("drouting", "gw_id_avp", '$avp(gw_id)')
    modparam("drouting", "gw_id_avp", '$avp(334)')
    ...

### `gw_priprefix_avp` (str)

The name of the avp for storing the PRI prefix of the current selected destination/gateway - once a new destination is selected (via the use_next_gw() function), the AVP will be updated with the PRI prefix of the new used destination.

Default value is NULL.

#### Set `gw_priprefix_avp` parameter

    ...
    modparam("drouting", "gw_priprefix_avp", '$avp(gw_priprefix)')
    ...

### `rule_id_avp` (str)

The name of the avp for storing the id of the current matched routing rule (see dr_rules table).

Default value is NULL.

#### Set `rule_id_avp` parameter

    ...
    modparam("drouting", "rule_id_avp", '$avp(rule_id)')
    modparam("drouting", "rule_id_avp", '$avp(335)')
    ...

### `rule_prefix_avp` (str)

The actual prefix that matched the routing rule (the part from RURI username that matched the routing rule).

Default value is NULL.

#### Set `rule_prefix_avp` parameter

    ...
    modparam("drouting", "rule_prefix_avp", '$avp(dr_prefix)')
    ...

### `carrier_id_avp` (str)

AVP to be populate with the ID string for the carrier the current GW belongs to.

Default value is NULL.

#### Set `carrier_id_avp` parameter

    ...
    modparam("drouting", "carrier_id_avp", '$avp(carrier_id)')
    ...

### `gw_sock_avp` (str)

The name of the avp for storing sockets for alternative destinations defined by ruri_avp.

Default value is $avp(___dr_sock__) if `use_partitions` parameter is 0 or $avp(___dr_sock__partition_name) where partition_name is the name of the partition containing the AVP (as fetched from the database) if `use_partitions` parameter is 1.

#### Set `gw_sock_avp` parameter

    ...
    modparam("drouting", "gw_sock_avp", '$avp(dr_sock)')
    modparam("drouting", "gw_sock_avp", '$avp(77)')
    ...

### `rule_attrs_avp` (str)

The name of the avp for storing rule attrs in case they are requested at least once in the script.

Default value is $avp(___dr_ru_att__) if `use_partitions` parameter is 0 or $avp(___dr_ru_att__partition_name) where partition_name is the name of the partition containing the AVP (as fetched from the database) if `use_partitions` parameter is 1.

#### Set `rule_attrs_avp` parameter

    ...
    modparam("drouting", "rule_attrs_avp", '$avp(dr_rule_attr)')
    modparam("drouting", "rule_attrs_avp", '$avp(11)')
    ...

### `define_blacklist` (str)

Defines a blacklist based on a list of GW types - the list will contain the IPs (no port, all protocols) of the GWs with the specified types.

Multiple instances of this param are allowed.

Default value is NULL.

#### Set `define_blacklist` parameter

    ...
    modparam("drouting", "define_blacklist", 'bl_name= 3,5,25,23')
    modparam("drouting", "define_blacklist", 'list= 4,2')
    ...

### `default_group` (int)

Group to be used if the caller (FROM user) is not found in the GROUP table.

Default value is NONE.

#### Set `default_group` parameter

    ...
    modparam("drouting", "default_group", 4)
    ...

### `force_dns` (int)

Force DNS resolving of GW/destination names (if not IPs) during startup. If not enabled, the GW name will be blindly used during routing.

Default value is 1 (enabled).

#### Set `force_dns` parameter

    ...
    modparam("drouting", "force_dns", 0)
    ...

### `persistent_state` (int)

Specifies whether the state column should be loaded at startup and flushed during runtime or not.

Default value is 1 (enabled).

#### Set the `persistent_state` parameter

    ...
    # disable all DB operations with the state of a gateway
    modparam("drouting", "persistent_state", 0)
    ...

### `no_concurrent_reload` (int)

If enabled, the module will not allow do run multiple dr_reload MI commands in parallel (with overlapping) Any new reload will be rejected (and discarded) while an existing reload is in progress.

If you have a large routing set (millions of rules/prefixes), you should consider disabling concurrent reload as they will exhaust the shared memory (by reloading into memory, in the same time, multiple instances of routing data).

Default value is 0 (disabled).

#### Set `no_concurrent_reload` parameter

    ...
    # do not allow parallel reload operations
    modparam("drouting", "no_concurrent_reload", 1)
    ...

### `probing_interval` (integer)

How often (in seconds) the probing of a destination should be done. If set to 0, the probing will be disabled as functionality (for all destinations)

Default value is 30.

#### Set `probing_interval` parameter

    ...
    modparam("drouting", "probing_interval", 60)
    ...

### `probing_method` (string)

The SIP method to be used for the probing requests.

Default value is "OPTIONS".

#### Set `probing_method` parameter

    ...
    modparam("drouting", "probing_method", "INFO")
    ...

### `probing_from` (string)

The FROM SIP URI to be advertised in the SIP probing requests.

Default value is "sip:prober@localhost".

#### Set `probing_from` parameter

    ...
    modparam("drouting", "probing_from", "sip:pinger@192.168.2.10")
    ...

### `probing_reply_codes` (string)

A comma separted list of SIP reply codes. The codes defined here will be considered as valid reply codes for probing messages, apart for 200.

Default value is NULL.

#### Set `probing_reply_codes` parameter

    ...
    modparam("drouting", "probing_reply_codes", "501, 403")
    ...

### `use_domain` (int)

Flag to configure whether to use domain match when querying database for user's routing group.

Default value is 1.

#### Set `use_domain` parameter

    ...
    modparam("drouting", "use_domain", 0)
    ...

### `drg_user_col` (str)

The name of the column in group db table where the username is stored.

Default value is username.

#### Set `drg_user_col` parameter

    ...
    modparam("drouting", "drg_user_col", "user")
    ...

### `drg_domain_col` (str)

The name of the column in group db table where the domain is stored.

Default value is domain.

#### Set `drg_domain_col` parameter

    ...
    modparam("drouting", "drg_domain_col", "host")
    ...

### `drg_grpid_col` (str)

The name of the column in group db table where the group id is stored.

Default value is groupid.

#### Set `drg_grpid_col` parameter

    ...
    modparam("drouting", "drg_grpid_col", "grpid")
    ...

### `use_partitions` (int)

Flag to configure whether to use partitions for routing. If this flag is set then the `db_partitions_url` and `db_partitions_table` variables become mandatory.

Default value is 0.

#### Set `use_partitions` parameter

    ...
    modparam("drouting", "use_partitions", 1)
    ...

### `db_partitions_url` (int)

The url to the database containing partition-specific information. (partition-specific information includes partition name, url to the database where information about the partition is preserved, the names of the tables in which it is preserved and the AVPs that can be accessed using the .cfg script). The `use_partitions` parameter must be set to 1.

Default value is "NULL".

#### Set `db_partitions_url` parameter

    ...
    modparam("drouting", "db_partitions_url", "mysql://user:password@localhost/opensips_partitions")
    ...

### `db_partitions_table` (int)

The name of the table containing partition definitions. To be used with `use_partitions` and `db_partitions_url`.

Default value is dr_partitions.

#### Set `db_partitions_table` parameter

    ...
    modparam("drouting", "db_partitions_table", "partition_defs")
    ...

### `partition_id_pvar` (pvar)

Variable which will store the name of the name partition when wildcard(*) operatior is used. Use_partitions must be set in order to use this parameter.

NOTE: The variable must be WRITABLE!

Default value is null(not used).

#### Set `partition_id_pvar` parameter

    ...
    modparam("drouting", "partition_id_pvar", "$var(matched_partition)")
    ...

## Exported Functions

### `do_routing([part_and_or_groupID], [flags], [gw_whitelist], [rule_attrs_pvar], [gw_attrs_pvar], [carrier_attrs_pvar])`

Function to trigger routing of the message according to the rules in the database table and the configured parameters.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE and LOCAL_ROUTE.

If you set `use_partitions` to 1 the part_or_groupID parameter becomes mandatory.

All parameters are optional. Any of them may be ignored, provided the necessary separation marks "," are properly placed.

- part_and_or_groupID - Specifies the group of the caller for routing purposes. Depending on the value of the `use_partitions` parameter, it contains:

  - the routing group the caller belongs to if `use_partitions` is 0 - this may be a statical numerical value or an AVP specification (value must be numerical type, string types are ignored!). If none specified the function will automatically try to query the dr_group table to get this information

  - the partition and routing group the caller belongs to, the format is: "partition':'[groupID]" if `use_partitions` parameter is 1 - both the partition name and the groupId may be statical values or AVP specifications. If no group is specified the function will try to query the dr_group table for the given partition to get this information. If * (wildcard) operator is used all partitions shall be checked.

- flags - Controls the behavior of the function. Possible flags are:

  - W - Instead of using the destination (from the rule definition) in the given order, sort them based on their weight.

  - F - Enable rule fallback; normally the engine is using a single rule for routing a call; by setting this flag, the engine will fallback and use rules with less priority or shorter prefix when all the destination from the current rules failed.

  - L - Do strict length matching over the prefix - actually DR engine will do full number matching and not prefix matching anymore.

  - C - Only check if the dialed number matches any routing rule, without loading / applying any routing info (no GW is set, the RURI is not altered)

- gw_whitelist - a comma separated white list of gateways. This will force routing over, at most, this list of carriers or gateways (in other words, the whitelist will be intersected with the results of the search through the rules).

- rule_attrs_pvar (output, optional)- a writable pseudo-variable which will be populated with the attributes of the matched dynamic routing rule.

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched gateway.

- carrier_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched carrier.

#### `do_routing` usage

    ...
    # all groups, sort on order, use_partitions is 0
    do_routing();
    ...
    # all groups, sort on order, use_partitions is 1, route by partition named "part"
    do_routing("part:");
    ...
    # group id 0, sort on order, use_partitions is 0
    do_routing("0");
    ...
    # group id 0, sort on order, use_partitions is 1, route by partition named "part"
    do_routing("part:0");
    ...
    # group id from $avp(10), sort on order, use_partitions is 0
    do_routing("$avp(10)");
    ...
    # all groups, sort on weights, use_partitions is 0
    do_routing("", "W");
    ...
    # all groups, use_partitions is 1, partition and group supplied by AVPs, do strict length matching
    do_routing("$avp(partition):$avp(grp)","L")
    ...
    # group id 2, sort on order, fallback rule and also return the gateway attributes
    do_routing("2", "F", , , "$var(gw_attributes)");
    ...

### `route_to_carrier(part_and_or_carrier_id, [gw_attrs_pvar], [carrier_attrs_pvar])`

Function to trigger the direct routing to a given carrier. In this case the routing is not done prefix based, but carrier based (call will be sent to the GWs of that carrier, based on carrier policy).

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE and LOCAL_ROUTE..

If you set `use_partitions` parameter to 1 you must supply the partition in which the carrier has been defined.

- part_and_or_carrier_id (mandatory):

  - the ID (name) of the carrier to be used, if `use_partitions` parameter is 0; pseudo-variables are accepted.

  - the partition and carrier to be used, if `use_partitions` parameter is 1. The format is "partition_name':'carrierId"; pseudo-variables are accepted.

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the currently matched gateway of this carrier.

- carrier_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of this carrier.

#### `route_to_carrier` usage when `use_partitions` parameter is 0

    ...
    if ( route_to_carrier("my_top_carrier", , "$var(carrier_att)") ) {
    	xlog("Routing to \"my_top_carrier\" - $var(carrier_att)\n");
    	t_on_failure("next_gw");
    	t_relay();
    	exit;
    }
    ...

#### `route_to_carrier` usage when `use_partitions` parameter is 1

    ...
    if ( route_to_carrier("my_partition:my_top_carrier", , "$var(carrier_att)") ) {
    	xlog("Routing to \"my_top_carrier\" - $var(carrier_att)\n");
    	t_on_failure("next_gw");
    	t_relay();
    	exit;
    }
    ...

#### `route_to_carrier` usage when `use_partitions` parameter is 1 with pseudovariables

    ...
    if ( route_to_carrier("$var(my_partition):$var(carrierId)") ) {
    	xlog("Routing to \"my_top_carrier\" - $var(carrier_att)\n");
    	t_on_failure("next_gw");
    	t_relay();
    	exit;
    }
    ...

### `route_to_gw(gw_id, [gw_attrs_pvar])`

Function to trigger the direct routing to a given gateway (or list of gateways). Attributes and per-gw processing will be available.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE and LOCAL_ROUTE.

If you set `use_partitions` parameter to 1 you must supply the partition in which the gateway has been defined.

- gw_id (mandatory) - the list of gateways to be used.

  - a comma separated list of gateway ID's to be used, if no `use_partition` parameter is 0. Pseudo-variables are accepted.

  - the desired partition, followed by a comma separated list of gateway ID's from that partition to be used, if `use_partition` parameter is 1. The format is: "partition_name':'gwId1, gwId2, gwId3". Pseudo-variables are accepted.

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the currently matched gateway.

#### `route_to_gw` usage when `use_partition` parameter is 0

    ...
    if ( route_to_gw("gw_europe") ) {
    	t_relay();
    	exit;
    }
    ...
    if ( route_to_gw("gw1,gw2,gw3", "$var(gw_attrs)") ) {
    	xlog("Relaying to first gateway from our list - $var(gw_attrs)\n");
    	t_relay();
    	exit;
    }
    ...

#### `route_to_gw` usage when `use_partition` parameter is 1

    ...
    if ( route_to_gw("my_partition:gw_europe") ) {
    	t_relay();
    	exit;
    }
    ...
    if ( route_to_gw("my_partition:gw1,gw2,gw3", "$var(gw_attrs)") ) {
    	xlog("Relaying to first gateway from our list - $var(gw_attrs)\n");
    	t_relay();
    	exit;
    }
    ...

### `use_next_gw([partition','] [rule_attrs_pvar], [gw_attrs_pvar], [carrier_attrs_pvar])/next_routing()`

The function takes the next available destination (set by do_routing, as alternative destinations) and pushes it into the RURI. Note that the function just sets the RURI (nothing more).

If a new RURI is set, the used destination is removed from the pending set of alternative destinations.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE and LOCAL_ROUTE.

The function returns true only if a new RURI was set. False is returned is no other alternative destinations are found or in case of an internal processing error. It may take the following optional parameters:

If you set `use_partitions` parameter to 1 you must supply the partition (the partition becomes mandatory) in which the gateways have been defined.

- partition (mandatory if `use_partitions` parameter is 1, otherwise it will be omitted altogether) It is the partition in which the gateways have been defined.

- rule_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched dynamic routing rule.

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched gateway.

- carrier_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched carrier.

#### `use_next_gw` usage

    ...
    if (use_next_gw()) {
    	t_relay();
    	exit;
    }
    ...
    # Also fetch the carrier attributes, if any
    if (use_next_gw(, , "$var(carrier_attrs)")) {
    	xlog("Carrier attributes of current gateway: $var(carrier_attrs)\n");
    	t_relay();
    	exit;
    }
    ...

#### `use_next_gw` usage when `use_partition` parameter is 1

    ...
    if (use_next_gw("my_partition")) {
    	t_relay();
    	exit;
    }
    ...
    # Also fetch the carrier attributes, if any
    if (use_next_gw("my_partition", , "$var(carrier_attrs)")) {
    	xlog("Carrier attributes of current gateway: $var(carrier_attrs)\n");
    	t_relay();
    	exit;
    }
    ...

### `goes_to_gw([partition','] [type], [flags], [gw_attrs_pvar])`

Function returns true if the destination of the current request (destination URI or Request URI) points (as IP) to one of the gateways. There no DNS lookups done if the domain part of the URI is not an IP.

This function does not change anything in the message.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE, BRANCH_ROUTE and LOCAL_ROUTE.

If you set `use_partitions` parameter to 1 you must supply the partition (the partition becomes mandatory) in which the gateways have been defined.

If `use_partitions` parameter is 0 all parameters are optional. Any of them may be ignored, provided the necessary separation marks "," are properly placed.

- partition (mandatory if `use_partitions` parameter is 1, otherwise it will be omitted altogether) - the name of the partition containing the gateway/destination to be checked.

- type (optional) - GW/destination type to be checked; when omitting this parameter or specifying a negative value i.e. "-1", matching will be done against all groups (in a given partition if `use_partition` parameter is 1; if `use_partitions` is 1 the partition being mandatory at this point, it is not possible to do matching against all the partitions)

- flags (optional) - what operations should be performed when a GW matches:

  - 's' (Strip) - apply to the username of RURI the strip defined by the GW

  - 'p' (Prefix) - apply to the username of RURI the prefix defined by the GW

  - 'i' (Gateway ID) - return the gateway id into gw_id_avp AVP

  - 'n' (Ignore port) - ignores port number during matching

  - 'c' (Carrier ID) - return the carrier id into carrier_id_avp AVP

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched gateway.

#### `goes_to_gw` usage when `use_partitions` parameter is 0

    ...
    if (goes_to_gw("1", , "$var(gw_attrs)")) {
    	sl_send_reply("403","Forbidden");
    	exit;
    }
    ...

#### `goes_to_gw` usage, when `use_partitions` parameter is 1

    ...
    if (goes_to_gw("my_partition", "1", , "$var(gw_attrs)")) {
    	sl_send_reply("403","Forbidden");
    	exit;
    }
    ...

### `is_from_gw([partition','] [type], [flag], [gw_attrs_pvar])`

The function checks if the sender of the message (its source IP) is a gateway from a certain group.

This function can be used from REQUEST_ROUTE, FAILURE_ROUTE and ONREPLY_ROUTE.

If you set `use_partitions` parameter to 1 you must supply the partition (the partition becomes mandatory) in which the gateways have been defined.

If `use_partitions` parameter is 0 all parameters are optional. Any of them may be ignored, provided the necessary separation marks "," are properly placed.

- partition (mandatory if `use_partitions` parameter is 1, otherwise it will be omitted altogether) - Partition containing the destination/gw to be checked. If *(wildcard) operator is used all partitions shall be checked.

- type (optional) - GW/destination type to be checked; when omitting this parameter or specifying a negative value i.e. "-1", matching will be done against all groups

- flags (optional) - what operations should be performed when a GW matches:

  - 's' (Strip) - apply to the username of RURI the strip defined by the GW

  - 'p' (Prefix) - apply to the username of RURI the prefix defined by the GW

  - 'i' (Gateway ID) - return the gateway id into gw_id_avp AVP

  - 'n' (Ignore port) - ignores port number during matching

  - 'c' (Carrier ID) - return the carrier id into carrier_id_avp AVP

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched gateway.

#### `is_from_gw` usage when `use_partitions` is 0

    ...
    if (is_from_gw("3","1") {
    }
    ...

#### `is_from_gw` usage when `use_partitions` is 1

    ...
    if (is_from_gw("my_partition","3","1") {
    }
    ...

### `dr_is_gw([partition,] src_avp, [type], [flag], [gw_attrs_pvar])`

The function checks if the ip address in pvar src_pv is a gateway from a certain group.

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE, FAILURE_ROUTE, BRANCH_ROUTE, LOCAL_ROUTE, STARTUP_ROUTE, TIMER_ROUTE and EVENT_ROUTE.

If you set `use_partitions` parameter to 1 you must supply the partition (the partition becomes mandatory) in which the gateways have been defined.

Meaning of the parameters is as follows:

- partition (mandatory if `use_partitions` parameter is 1, otherwise it will be omitted altogether) - Partition containing the destinations/gateways to be checked.

- src_avp (mandatory) - avp containing a SIP URI. Does not support other OpenSIPS pseudo-variables.

- type (optional) - GW/destination type to be checked; when omitting this parameter or specifying a negative value i.e. "-1", matching will be done against all groups

- flags (optional) - what operations should be performed when a GW matches:

  - 's' (Strip) - apply to the username of RURI the strip defined by the GW

  - 'p' (Prefix) - apply to the username of RURI the prefix defined by the GW

  - 'i' (Gateway ID) - return the gateway id into gw_id_avp pvar

  - 'n' (Ignore port) - ignores port number

  - 'c' (Carrier ID) - return the carrier id into carrier_id_avp AVP

- gw_attrs_pvar (output, optional) - a writable pseudo-variable which will be populated with the attributes of the matched gateway.

#### `dr_is_gw` usage when `use_partitions` is 0

    ...
    if (dr_is_gw("$avp(uac)","3") {
    }
    ...

#### `dr_is_gw` usage when `use_partitions` is 1

    ...
    if (dr_is_gw("my_partition","$avp(uac)","3") {
    }
    ...

### `dr_disable()`

Marks as disabled the last destination that was used for the current call. The disabling done via this function will prevent the destination to be used for usage from now on. The probing mechanism can re-enable this peer (see the probing section in the beginning)

This function can be used from REQUEST_ROUTE and FAILURE_ROUTE.

If you set `use_partitions` parameter to 1 you must supply the partition (the partition becomes mandatory) in which the gateway to be disabled is defined.

- partition (mandatory if `use_partitions` parameter is 1, otherwise it will be omitted altogether) - Partition containing the destination/gateway to be disabled.

#### `dr_disable()` usage when `use_partitions` is 0

    ...
    if (t_check_status("(408)|(5[0-9][0-9])")) {
    	dr_disable();

    }

    ...

#### `dr_disable()` usage when `use_partitions` is 1

    ...
    if (t_check_status("(408)|(5[0-9][0-9])")) {
    	dr_disable("my_partition");

    }

    ...

## Exported MI Functions

### `dr_reload`

Command to reload routing rules from database. If `use_partitions` is set to 1 you can reload just a partition given a parameter, if no parameter is supplied then all the partitions will be reloaded.

If `use_partitions` is 0 it takes no parameter.

MI FIFO Command Format:

    		:dr_reload:fifo_reply
    		partition_name (optional)
    		_empty_line_

### `dr_gw_status`

Gets or sets the status (enabled or disabled) of a gateway. The function may take from 0 to 3 parameters.

- if `use_partitions` is set to 0 - if no parameter is provided, it will list all gateways along with their status. If one parameter is provided, that must be the id of a gateway and the function will return the status of that gateway. If 2 parameters are provided, first must be the ID of the ID of a GW and the second must be the new status to be forced for that GW (0 - disable, 1 - enable).

- if `use_partitions` is set to 1 - the first parameter must be the partition (the partition is mandatory). If just one parameter is provided it will the display the statuses of all the gateways in the given partition. If two parameters are provided, the first must be the partition, and the second must be the gateway Id. If three parameters are provided, the first must be the partition, the second must be the gateway and the third will be the new status to be forced for tat GW (0 - disable, 1 - enable)

MI FIFO Command Format:

    		:dr_gw_status:_reply_fifo_file_
    		partition_name (mandatory if use_partitions is 1, otherwise will be omitted altogether)
    		GW_id
    		status (optional)
    		_empty_line_

#### `dr_gw_status` usage when `use_partitions` is set to 0

    $ ./opensipsctl fifo dr_gw_status 2
    State:: Active
    $ ./opensipsctl fifo dr_gw_status 2 0
    $ ./opensipsctl fifo dr_gw_status 2
    Enabled:: Disabled MI
    $ ./opensipsctl fifo dr_gw_status 3
    Enabled:: Inactive

#### `dr_gw_status` usage when `use_partitions`is set to 1

    $ ./opensipsctl fifo dr_gw_status part_1 my_gw
    State:: Active
    $ ./opensipsctl fifo dr_gw_status my_partition 3 0
    $ ./opensipsctl fifo dr_gw_status partition7 dsbl_gw 2
    Enabled:: Disabled MI
    $ ./opensipsctl fifo dr_gw_status partition8 gw3
    Enabled:: Inactive

### `dr_carrier_status`

Gets or sets the status (enabled or disabled) of a carrier. The function may take from 0 to 3 parameters.

- if `use_partition` is set to 0 - if no parameter is provided it will list all the carriers along with their status. If one parameter is provided, that must be the id of carrier and the function will return the status of that carrier. If 2 parameters are provided, first must be the Id of a carrier and the second must be the new status to be forced for that carrier

- if `use_partition` is set to 1 - the first parameter must be the partition (the partition becomes mandatory). If one parameter is supplied, it will be the partition, and it will display the statuses of the carriers contained in that partition. If two parameters are supplied, the second must be the carrierId, and the command will display the status of the selected carrier. If three parameters are supplied, the first two will be the partition name and the carrierId while the third parameter will be the new status to be forced for that carrier.

MI FIFO Command Format:

    		:dr_carrier_status:_reply_fifo_file_
    		partition_name (mandatory if use_partition is 1, otherwise it will be omitted)
    		carrier_id
    		status (optional)
    		_empty_line_

#### `dr_carrier_status` usage when `use_partitions` is 0

    $ ./opensipsctl fifo dr_carrier_status CR1
    Enabled:: no
    $ ./opensipsctl fifo dr_carrier_status CR1 1
    $ ./opensipsctl fifo dr_carrier_status CR1
    Enabled:: yes

#### `dr_carrier_status` usage when `use_partitions` is 1

    $ ./opensipsctl fifo dr_carrier_status my_partition CR1
    Enabled:: no
    $ ./opensipsctl fifo dr_carrier_status partition_1 CR1 1
    $ ./opensipsctl fifo dr_carrier_status partition_3 CR1
    Enabled:: yes

### `dr_reload_status`

Gets the time of the last reload for any partition. The function may take at most one parameter.

- if `use_partition` is set to 0 - the function doesn't receive any parameter. It will list the date of the last reload for the default (and only) partition.

- if `use_partition` is set to 1 - if no parameter is supplied it will list the time of the last update for every partition. If one parameter is supplied, then this must be the partition name, and the function will list the time of the last reload for that given partition.

MI FIFO Command Format:

    		:dr_reload_status:_reply_fifo_file_
    		partition_name (if use_partition is 1 it may be omitted, but if use_partition
    is 0 it must be omitted)
    		_empty_line_

#### `dr_reload_status` usage when `use_partitions` is 0

    $ ./opensipsctl fifo dr_reload_status
    Date:: Tue Aug 12 12:26:00 2014

#### `dr_reload_status` usage when `use_partitions` is 1

    $ ./opensipsctl fifo dr_reload_status
    Partition:: part_test Date=Tue Aug 12 12:24:13 2014
    Partition:: part_2 Date=Tue Aug 12 12:24:13 2014
    $ ./opensipsctl fifo dr_reload_status part_test
    Partition:: part_test Date=Tue Aug 12 12:24:13 2014

### `dr_number_routing`

Gets the matched prefix along with the list of the gateways / carriers to which a number would be routed when using the do_routing function

- if `use_partition` is set to 1 the function will have 3 parameters:

  - partition name
  - group id - the group id of the rules to check against
  - number - the number to test against

- if `use_partition` is set to 0 the function will have 2 parameters:

  - group id - the group id of the rules to check against
  - number - the number to test against

Note: The group id may be omitted - just as with the do_routing function.

## Exported Events

### `E_DROUTING_STATUS`

This event is raised when the module changes the state of a gateway, either through MI or probing.

Parameters:

- gwid - the gateway identifier.

- address - the address of the gateway.

- status - disabled MI if the gateway was disabled using MI commands, probing if the gateway is being pinged, inactive if it was disabled from the script or active if the gateway is enabled.

## Installation

The module requires 4 tables in the OpenSIPS database: dr_groups, dr_gateways, dr_carriers, dr_rules. The SQL syntax to create them can be found in the drouting-create.sql script, located in the database directories of the opensips/scripts folder. You can also find the complete database documentation on the project webpage, &osipsdbdocslink;.