1.1.1. Contact matching

How the contacts are matched (dor same AOR - Address of Record) is an important aspect of the usrloc modules, especialy in the context of NAT traversal - this raise mre problems since contacts from different phones of same users may overlap (if behind NATs with same configuration) or the re-register contact of same phone may be seen as a new one (due different binding via NAT).

The SIP RFC 3261 publishes a matching algorithm based only on the contact string with callid and cseq number extra checking (if callid is the same, it must have a higher cseq number, otherwise invalid). But as argumented above, this is not enough in NAT traversal context, so the OpenSER implementation of contact machting offers more algorithms:

• contact based only - it strict RFC 3261 compiancy - the contact is matched as string and extra checked via callid and cseg (if callid is the same, it must have a higher cseq number, otherwise invalid).

• contact nad callid based - it an extension of the first case - the contact and callid must matched as string; the cseg must be higher than the previous one - so be careful how you deal with REGISTER retransmissions in this case.

How to control/select the contact maching algorithm, please see the module parameter matching_mode at Section 1.3.21.

1.2.1. OpenSER Modules

The following modules must be loaded before this module:

• Optionally a database module.

1.2.2. External Libraries or Applications

The following libraries or applications must be installed before running OpenSER with this module loaded:

• None.

1.3.1. nat_bflag (integer)

The index of the branch flag to be used as NAT marker (if the contact is or not natted). This is a branch flag and it will be imported and used by all other modules depending of usrloc module.

Default value is "not set".

...
modparam("usrloc", "nat_bflag", 3)
...

1.3.2. user_column (string)

Name of column containing usernames.

Default value is "username".

...
modparam("usrloc", "user_column", "username")
...

1.3.3. domain_column (string)

Name of column containing domains.

Default value is "domain".

...
modparam("usrloc", "domain_column", "domain")
...

1.3.4. contact_column (string)

Name of column containing contacts.

Default value is "contact".

...
modparam("usrloc", "contact_column", "contact")
...

1.3.5. expires_column (string)

Name of column containing expires value.

Default value is "expires".

...
modparam("usrloc", "expires_column", "expires")
...

1.3.6. q_column (string)

Name of column containing q values.

Default value is "q".

...
modparam("usrloc", "q_column", "q")
...

1.3.7. callid_column (string)

Name of column containing callid values.

Default value is "callid".

...
modparam("usrloc", "callid_column", "callid")
...

1.3.8. cseq_column (string)

Name of column containing cseq numbers.

Default value is "cseq".

...
modparam("usrloc", "cseq_column", "cseq")
...

1.3.9. methods_column (string)

Name of column containing supported methods.

Default value is "methods".

...
modparam("usrloc", "methods_column", "methods")
...

1.3.10. flags_column (string)

Name of column to save the internal flags of the record.

Default value is "flags".

...
modparam("usrloc", "flags_column", "flags")
...

1.3.11. cflags_column (string)

Name of column to save the branch/contact flags of the record.

Default value is "cflags".

...
modparam("usrloc", "cflags_column", "cflags")
...

1.3.12. user_agent_column (string)

Name of column containing user-agent values.

Default value is "user_agent".

...
modparam("usrloc", "user_agent_column", "user_agent")
...

1.3.13. received_column (string)

Name of column containing the source IP, port, and protocol from the REGISTER message.

Default value is "received".

...
modparam("usrloc", "received_column", "received")
...

1.3.14. socket_column (string)

Name of column containing the received socket information (IP:port) for the REGISTER message.

Default value is "socket".

...
modparam("usrloc", "socket_column", "socket")
...

1.3.15. path_column (string)

Name of column containing the Path header.

Default value is "path".

...
modparam("usrloc", "path_column", "path")
...

1.3.16. use_domain (integer)

If the domain part of the user should be also saved and used for identifing the user (along with the username part). Useful in multi domain scenarios. Non 0 value means true.

Default value is "0 (false)".

...
modparam("usrloc", "use_domain", 1)
...

1.3.17. desc_time_order (integer)

If the user's contacts should be kept timestamp ordered; otherwise the contact will be ordered based on q value. Non 0 value means true.

Default value is "0 (false)".

...
modparam("usrloc", "desc_time_order", 1)
...

1.3.18. timer_interval (integer)

Number of seconds between two timer runs. The module uses timer to delete expired contacts, synchronize with database and other tasks, that need to be run periodically.

Default value is 60.

...
modparam("usrloc", "timer_interval", 120)
...

1.3.19. db_url (string)

URL of the database that should be used.

Default value is "mysql://openser:openserrw@localhost/openser".

...
modparam("usrloc", "db_url", "mysql://username:password@localhost/openser")
...

1.3.20. db_mode (integer)

The usrloc module can utilize database for persistent contact storage. If you use database, your contacts will survive machine restarts or SW crashes. The disadvantage is that accessing database can be very time consuming. Therefore, usrloc module implements four database accessing modes:

• 0 - This disables database completely. Only memory will be used. Contacts will not survive restart. Use this value if you need a really fast usrloc and contact persistence is not necessary or is provided by other means.

• 1 - Write-Through scheme. All changes to usrloc are immediately reflected in database too. This is very slow, but very reliable. Use this scheme if speed is not your priority but need to make sure that no registered contacts will be lost during crash or reboot.

• 2 - Write-Back scheme. This is a combination of previous two schemes. All changes are made to memory and database synchronization is done in the timer. The timer deletes all expired contacts and flushes all modified or new contacts to database. Use this scheme if you encounter high-load peaks and want them to process as fast as possible. The mode will not help at all if the load is high all the time. Also, latency of this mode is much lower than latency of mode 1, but slightly higher than latency of mode 0.

• 3 - DB-Only scheme. No memory cache is kept, all operations being directly performed with the database. The timer deletes all expired contacts from database - cleans after clients that didn't un-register or re-register. The mode is useful if you configure more servers sharing the same DB without any replication at SIP level. The mode may be slower due the high number of DB operation. For example NAT pinging is a killer since during each ping cycle all nated contact are loaded from the DB; The lack of memory caching also disable the location watcher registration (in will not work with PA module) and disable the statistics exports.

In case of crash or restart contacts that are in memory only and haven't been flushed yet will get lost. If you want minimize the risk, use shorter timer interval.

Default value is 0.

...
modparam("usrloc", "db_mode", 2)
...

1.3.21. matching_mode (integer)

What contact matching algorithm to be used. Refer to section Section 1.1.1 for the description of the algorithms.

The parameter may take the following values:

• 0 - CONTACT ONLY based matching algorithm.

• 1 - CONTACT and CALLID based matching algorithm.

Default value is 0 (CONTACT_ONLY).

...
modparam("usrloc", "matching_mode", 1)
...

1.3.22. cseq_delay (integer)

Delay (in seconds) for accepting as retransmissions register requests with same Call-ID and Cseq. The delay is calculated starting from the receiving time of the first register with that Call-ID and Cseq.

Retransmissions within this delay interval will be accepted and replied as the original request, but no update will be done in location. If the delay is exceeded, error is reported.

A value of 0 disable the retransmission detection.

Default value is "20 seconds".

...
modparam("usrloc", "cseq_delay", 5)
...

1.3.23. fetch_rows (integer)

The number of the rows to be fetched at once from database when loading the location records. This value can be used to tune the load time at startup. For 1MB of private memory (default) it should be below 4000. The database driver must support fetch_result() capability.

Default value is "2000".

...
modparam("usrloc", "fetch_rows", 3000)
...

1.3.24. hash_size (integer)

The number of entries of the hash table used by usrloc to store the location records is 2^hash_size. For hash_size=4, the number of entries of the hash table is 16.

Default value is "9".

...
modparam("usrloc", "hash_size", 10)
...

1.5.1. ul_rm

Deletes an entire AOR record (including its contacts).

Parameters:

• table name - table where the AOR is removed from (Ex: location).

• AOR - user AOR in username[@domain] format (domain must be supplied only if use_domain option is on).

1.5.2. ul_rm_contact

Deletes a contact from an AOR record.

Parameters:

• table name - table where the AOR is removed from (Ex: location).

• AOR - user AOR in username[@domain] format (domain must be supplied only if use_domain option is on).

• contact - exact contact to be removed

1.5.3. ul_dump

Dumps the entire content of the USRLOC in memory cache

Parameters:

• brief - (optional, may not be present); if equals to string "brief", a brief dump will be done (only AOR and contacts, with no other details)

1.5.4. ul_flush

Triggers the flush of USRLOC memory cache into DB.

1.5.5. ul_add

Adds a new contact for an user AOR.

Parameters:

• table name - table where the contact will be added (Ex: location).

• AOR - user AOR in username[@domain] format (domain must be supplied only if use_domain option is on).

• contact - contact string to be added

• expires - expires value of the contact

• Q - Q value of the contact

• unused - unused attribute (kept for backword compatibility)

• flags - internal USRLOC flags of the contact

• cflags - per branch flags of the contact

• methods - mask with supported requests of the contact

1.5.6. ul_show_contact

Dumps the contacts of an user AOR.

Parameters:

• table name - table where the AOR resides (Ex: location).

• AOR - user AOR in username[@domain] format (domain must be supplied only if use_domain option is on).

1.6.1. users

Number of AOR existing in the USRLOC memory cache for that domain - can not be resetted; this statistic will be register for each used domain (Ex: location).

1.6.2. contacts

Number of contacts existing in the USRLOC memory cache for that domain - can not be resetted; this statistic will be register for each used domain (Ex: location).

1.6.3. expires

Total number of expired contacts for that domain - can be resetted; this statistic will be register for each used domain (Ex: location).

1.6.4. registered_users

Total number of AOR existing in the USRLOC memory cache for all domains - can not be resetted.

2.1.1. ul_register_domain(name)

The function registers a new domain. Domain is just another name for table used in registrar. The function is called from fixups in registrar. It gets name of the domain as a parameter and returns pointer to a new domain structure. The fixup than 'fixes' the parameter in registrar so that it will pass the pointer instead of the name every time save() or lookup() is called. Some usrloc functions get the pointer as parameter when called. For more details see implementation of save function in registrar.

Meaning of the parameters is as follows:

• const char* name - Name of the domain (also called table) to be registered.

2.1.2. ul_insert_urecord(domain, aor, rec)

The function creates a new record structure and inserts it in the specified domain. The record is structure that contains all the contacts for belonging to the specified username.

Meaning of the parameters is as follows:

• udomain_t* domain - Pointer to domain returned by ul_register_udomain.

• str* aor - Address of Record (aka username) of the new record (at this time the record will contain no contacts yet).

• urecord_t** rec - The newly created record structure.

2.1.3. ul_delete_urecord(domain, aor)

The function deletes all the contacts bound with the given Address Of Record.

Meaning of the parameters is as follows:

• udomain_t* domain - Pointer to domain returned by ul_register_udomain.

• str* aor - Address of record (aka username) of the record, that should be deleted.

2.1.4. ul_get_urecord(domain, aor)

The function returns pointer to record with given Address of Record.

Meaning of the parameters is as follows:

• udomain_t* domain - Pointer to domain returned by ul_register_udomain.

• str* aor - Address of Record of request record.

2.1.5. ul_lock_udomain(domain)

The function lock the specified domain, it means, that no other processes will be able to access during the time. This prevents race conditions. Scope of the lock is the specified domain, that means, that multiple domain can be accessed simultaneously, they don't block each other.

Meaning of the parameters is as follows:

• udomain_t* domain - Domain to be locked.

2.1.6. ul_unlock_udomain(domain)

Unlock the specified domain previously locked by ul_lock_udomain.

Meaning of the parameters is as follows:

• udomain_t* domain - Domain to be unlocked.

2.1.7. ul_release_urecord(record)

Do some sanity checks - if all contacts have been removed, delete the entire record structure.

Meaning of the parameters is as follows:

• urecord_t* record - Record to be released.

2.1.8. ul_insert_ucontact(record, contact, expires, q, callid, cseq, flags, cont, ua, sock)

The function inserts a new contact in the given record with specified parameters.

Meaning of the parameters is as follows:

• urecord_t* record - Record in which the contact should be inserted.

• str* contact - Contact URI.

• time_t expires - Expires of the contact in absolute value.

• float q - q value of the contact.

• str* callid - Call-ID of the REGISTER message that contained the contact.

• int cseq - CSeq of the REGISTER message that contained the contact.

• unsigned int flags - Flags to be set.

• ucontact_t* cont - Pointer to newly created structure.

• str* ua - User-Agent of the REGISTER message that contained the contact.

• struct socket_info *sock - socket on which the REGISTER message was received on.

2.1.9. ul_delete_ucontact (record, contact)

The function deletes given contact from record.

Meaning of the parameters is as follows:

• urecord_t* record - Record from which the contact should be removed.

• ucontact_t* contact - Contact to be deleted.

2.1.10. ul_get_ucontact(record, contact)

The function tries to find contact with given Contact URI and returns pointer to structure representing the contact.

Meaning of the parameters is as follows:

• urecord_t* record - Record to be searched for the contact.

• str_t* contact - URI of the request contact.

2.1.11. ul_get_all_ucontacts (buf, len, flags)

The function retrieves all contacts of all registered users and returns them in the caller-supplied buffer. If the buffer is too small, the function returns positive value indicating how much additional space would be necessary to accommodate all of them. Please note that the positive return value should be used only as a "hint", as there is no guarantee that during the time between two subsequent calls number of registered contacts will remain the same.

If flag parameter is set to non-zero value then only contacts that have the specified flags set will be returned. It is, for example, possible to list only contacts that are behind NAT.

Meaning of the parameters is as follows:

• void* buf - Buffer for returning contacts.

• int len - Length of the buffer.

• unsigned int flags - Flags that must be set.

2.1.12. ul_update_ucontact(contact, expires, q, callid, cseq, set, res, ua, sock)

The function updates contact with new values.

Meaning of the parameters is as follows:

• ucontact_t* contact - Contact URI.

• time_t expires - Expires of the contact in absolute value.

• float q - q value of the contact.

• str* callid - Call-ID of the REGISTER message that contained the contact.

• int cseq - CSeq of the REGISTER message that contained the contact.

• unsigned int set - OR value of flags to be set.

• unsigned int res - OR value of flags to be reset.

• str* ua - User-Agent of the REGISTER message that contained the contact.

• struct socket_info *sock - socket on which the REGISTER message was received on.

2.1.13. ul_bind_ursloc( api )

The function imports all functions that are exported by the USRLOC module. Overs for other modules which want to user the internal USRLOC API an easy way to load and access the functions.

Meaning of the parameters is as follows:

• usrloc_api_t* api - USRLOC API

2.1.14. ul_register_ulcb(type ,callback, param)

The function register with USRLOC a callback function to be called when some event occures inside USRLOC.

Meaning of the parameters is as follows:

• int types - type of event for which the callback should be called (see usrloc/ul_callback.h).

• ul_cb f - callback function; see usrloc/ul_callback.h for prototype.

• void *param - some parameter to be passed to the callback each time when it is called.

2.1.15. ul_get_num_users()

The function loops through all domains summing up the number of users.

2.1.16. ul_register_watcher()

Obsolete function - to be removed in the future.

2.1.17. ul_unregister_watcher()

Obsolete function - to be removed in the future.