$Revision: 1.2 $
$Date: 2005/08/24 13:24:29 $

# Functions

## `www_challenge(realm,qop)`

The function challenges a user agent. It will generate a WWW-Authorize header field containing a digest challenge, it will put the header field into a response generated from the request the server is processing and send the reply. Upon reception of such a reply the user agent should compute credentials and retry the request. For more information regarding digest authentication see RFC2617.

Meaning of the parameters is as follows:

- realm - Realm is a opaque string that the user agent should present to the user so he can decide what username and password to use. Usually this is domain of the host the server is running on.

  If an empty string "" is used then the server will generate it from the request. In case of REGISTER requests To header field domain will be used (because this header field represents a user being registered), for all other messages From header field domain will be used.

- qop - Value of this parameter can be either "1" or "0". When set to 1 then the server will put qop parameter in the challenge. When set to 0 then the server will not put qop parameter in the challenge. It is strongly recommended to use qop parameter, however there are still some user agents that cannot handle qop parameter properly so we made this optional. On the other hand there are still some user agents that cannot handle request without qop parameter too.

### www_challenge usage

    ...
    if (www_authorize("iptel.org", "subscriber")) {
        www_challenge("iptel.org", "1");
    };
    ...

## `proxy_challenge(realm, qop)`

The function challenges a user agent. It will generate a Proxy-Authorize header field containing a digest challenge, it will put the header field into a response generated from the request the server is processing and send the reply. Upon reception of such a reply the user agent should compute credentials and retry the request. For more information regarding digest authentication see RFC2617.

Meaning of the parameters is as follows:

- realm - Realm is a opaque string that the user agent should present to the user so he can decide what username and password to use. Usually this is domain of the host the server is running on.

  If an empty string "" is used then the server will generate it from the request. From header field domain will be used as realm.

- qop - Value of this parameter can be either "1" or "0". When set to 1 then the server will put qop parameter in the challenge. When set to 0 then the server will not put qop parameter in the challenge. It is strongly recommended to use qop parameter, however there are still some user agents that cannot handle qop parameter properly so we made this optional. On the other hand there are still some user agents that cannot handle request without qop parameter too.

### proxy_challenge usage

    ...
    if (!proxy_authorize("", "subscriber)) {
        proxy_challenge("", "1");  # Realm will be autogenerated
    };
    ...

## `consume_credentials()`

This function removes previously authorized credentials from the message being processed by the server. That means that the downstream message will not contain credentials there were used by this server. This ensures that the proxy will not reveal information about credentials used to downstream elements and also the message will be a little bit shorter. The function must be called after `www_authorize` or `proxy_authorize`.

### consume_credentials example

    ...
    if (www_authorize("", "subscriber)) {
        consume_credentials();
    };
    ...

## `is_rpid_user_e164()`

The function checks if the SIP URI received from the database or radius server and will potentially be used in Remote-Party-ID header field contains an E164 number (+ followed by up to 15 decimal digits) in its user part. Check fails, if no such SIP URI exists (i.e. radius server or database didn't provide this information).

### is_rpid_user_e164 usage

    ...
    if (is_rpid_user_e164()) {
        # do something here
    };
    ...

## `append_rpid_hf()`

Appends to the message a Remote-Party-ID header that contains header 'Remote-Party-ID: ' followed by the saved value of the SIP URI received from the database or radius server followed by the value of module parameter radius_rpid_suffix. The function does nothing if no saved SIP URI exists.

### append_rpid_hf usage

    ...
    append_rpid_hf();  # Append Remote-Party-ID header field
    ...

## `append_rpid_hf(prefix, suffix)`

This function is the same as the function described in . The only difference is that it accepts two parameters, prefix and suffix to be added to Remote-Party-ID header field. This function ignores rpid_prefix and rpid_suffix parameters, instead of that allows to set them for every call.

Meaning of the parameters is as follows:

- prefix - Prefix of the Remote-Party-ID URI. The string will be added at the begining of body of the header field, just before the URI.

- suffix - Suffix of the Remote-Party-ID header field. The string will be appended at the end of the header field. It can be used to set various URI parameters, for example.

### append_rpid_hf(prefix, suffix) usage

    ...
    append_rpid_hf("", ";party=calling;id-type=subscriber;screen=yes");  # Append Remote-Party-ID header field
    ...