[thirdparty/asterisk.git] / res / res_pjsip_outbound_registration.c

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*** MODULEINFO
        <depend>pjproject</depend>
        <depend>res_pjsip</depend>
        <use type="module">res_statsd</use>
        <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <pjsip.h>
#include <pjsip_ua.h>

#include "asterisk/res_pjsip.h"
#include "asterisk/res_pjsip_cli.h"
#include "asterisk/module.h"
#include "asterisk/taskprocessor.h"
#include "asterisk/cli.h"
#include "asterisk/stasis_system.h"
#include "asterisk/threadstorage.h"
#include "asterisk/threadpool.h"
#include "asterisk/statsd.h"
#include "res_pjsip/include/res_pjsip_private.h"
#include "asterisk/vector.h"
#include "asterisk/pbx.h"

/*** DOCUMENTATION
        <configInfo name="res_pjsip_outbound_registration" language="en_US">
                <synopsis>SIP resource for outbound registrations</synopsis>
                <description><para>
                        <emphasis>Outbound Registration</emphasis>
                        </para>
                        <para>This module allows <literal>res_pjsip</literal> to register to other SIP servers.</para>
                </description>
                <configFile name="pjsip.conf">
                        <configObject name="registration">
                                <synopsis>The configuration for outbound registration</synopsis>
                                <description><para>
                                        Registration is <emphasis>COMPLETELY</emphasis> separate from the rest of
                                        <literal>pjsip.conf</literal>. A minimal configuration consists of
                                        setting a <literal>server_uri</literal> and a <literal>client_uri</literal>.
                                </para></description>
                                <configOption name="auth_rejection_permanent" default="yes">
                                        <synopsis>Determines whether failed authentication challenges are treated
                                        as permanent failures.</synopsis>
                                        <description><para>If this option is enabled and an authentication challenge fails,
                                        registration will not be attempted again until the configuration is reloaded.</para></description>
                                </configOption>
                                <configOption name="client_uri">
                                        <synopsis>Client SIP URI used when attemping outbound registration</synopsis>
                                        <description><para>
                                                This is the address-of-record for the outbound registration (i.e. the URI in
                                                the To header of the REGISTER).</para>
                                                <para>For registration with an ITSP, the client SIP URI may need to consist of
                                                an account name or number and the provider's hostname for their registrar, e.g.
                                                client_uri=1234567890@example.com. This may differ between providers.</para>
                                                <para>For registration to generic registrars, the client SIP URI will depend
                                                on networking specifics and configuration of the registrar.
                                        </para></description>
                                </configOption>
                                <configOption name="contact_user" default="s">
                                        <synopsis>Contact User to use in request. If this value is not set, this defaults to 's'</synopsis>
                                </configOption>
                                <configOption name="contact_header_params">
                                        <synopsis>Header parameters to place in the Contact header</synopsis>
                                </configOption>
                                <configOption name="expiration" default="3600">
                                        <synopsis>Expiration time for registrations in seconds</synopsis>
                                </configOption>
                                <configOption name="max_retries" default="10">
                                        <synopsis>Maximum number of registration attempts.</synopsis>
                                        <description><para>
                                                This sets the maximum number of registration attempts that are made before
                                                stopping any further attempts. If set to 0 then upon failure no further attempts
                                                are made.
                                        </para></description>
                                </configOption>
                                <configOption name="security_negotiation" default="no">
                                        <synopsis>The kind of security agreement negotiation to use. Currently, only mediasec is supported.</synopsis>
                                        <description>
                                                <enumlist>
                                                        <enum name="no" />
                                                        <enum name="mediasec" />
                                                </enumlist>
                                        </description>
                                </configOption>
                                <configOption name="security_mechanisms">
                                        <synopsis>List of security mechanisms supported.</synopsis>
                                        <description><para>
                                                This is a comma-delimited list of security mechanisms to use. Each security mechanism
                                                must be in the form defined by RFC 3329 section 2.2.
                                        </para></description>
                                </configOption>
                                <configOption name="outbound_auth" default="">
                                        <synopsis>Authentication object(s) to be used for outbound registrations.</synopsis>
                                        <description><para>
                                                This is a comma-delimited list of <replaceable>auth</replaceable>
                                                sections defined in <filename>pjsip.conf</filename> used to respond
                                                to outbound authentication challenges.</para>
                                                <note><para>
                                                Using the same auth section for inbound and outbound
                                                authentication is not recommended.  There is a difference in
                                                meaning for an empty realm setting between inbound and outbound
                                                authentication uses.  See the auth realm description for details.
                                                </para></note>
                                        </description>
                                </configOption>
                                <configOption name="outbound_proxy" default="">
                                        <synopsis>Full SIP URI of the outbound proxy used to send registrations</synopsis>
                                </configOption>
                                <configOption name="max_random_initial_delay" default="10">
                                        <synopsis>Maximum interval in seconds for which an initial registration may be randomly delayed</synopsis>
                                        <description>
                                                <para>By default, registrations are randomly delayed by a small amount to prevent
                                                too many registrations from being made simultaneously.</para>
                                                <para>Depending on your system usage, it may be desirable to set this to a smaller
                                                or larger value to have fine grained control over the size of this random delay.</para>
                                        </description>
                                </configOption>
                                <configOption name="retry_interval" default="60">
                                        <synopsis>Interval in seconds between retries if outbound registration is unsuccessful</synopsis>
                                </configOption>
                                <configOption name="forbidden_retry_interval" default="0">
                                        <synopsis>Interval used when receiving a 403 Forbidden response.</synopsis>
                                        <description><para>
                                                If a 403 Forbidden is received, chan_pjsip will wait
                                                <replaceable>forbidden_retry_interval</replaceable> seconds before
                                                attempting registration again. If 0 is specified, chan_pjsip will not
                                                retry after receiving a 403 Forbidden response. Setting this to a non-zero
                                                value goes against a "SHOULD NOT" in RFC3261, but can be used to work around
                                                buggy registrars.
                                        </para></description>
                                </configOption>
                                <configOption name="fatal_retry_interval" default="0">
                                        <synopsis>Interval used when receiving a Fatal response.</synopsis>
                                        <description><para>
                                                If a fatal response is received, chan_pjsip will wait
                                                <replaceable>fatal_retry_interval</replaceable> seconds before
                                                attempting registration again. If 0 is specified, chan_pjsip will not
                                                retry after receiving a fatal (non-temporary 4xx, 5xx, 6xx) response.
                                                Setting this to a non-zero value may go against a "SHOULD NOT" in RFC3261,
                                                but can be used to work around buggy registrars.</para>
                                                <note><para>if also set the <replaceable>forbidden_retry_interval</replaceable>
                                                takes precedence over this one when a 403 is received.
                                                Also, if <replaceable>auth_rejection_permanent</replaceable> equals 'yes' then
                                                a 401 and 407 become subject to this retry interval.</para></note>
                                        </description>
                                </configOption>
                                <configOption name="server_uri">
                                        <synopsis>SIP URI of the server to register against</synopsis>
                                        <description><para>
                                                This is the URI at which to find the registrar to send the outbound REGISTER. This URI
                                                is used as the request URI of the outbound REGISTER request from Asterisk.</para>
                                                <para>For registration with an ITSP, the setting may often be just the domain of
                                                the registrar, e.g. sip:sip.example.com.
                                        </para></description>
                                </configOption>
                                <configOption name="transport">
                                        <synopsis>Transport used for outbound authentication</synopsis>
                                        <description>
                                                <note><para>A <replaceable>transport</replaceable> configured in
                                                <literal>pjsip.conf</literal>. As with other <literal>res_pjsip</literal> modules, this will use the first available transport of the appropriate type if unconfigured.</para></note>
                                        </description>
                                </configOption>
                                <configOption name="line">
                                        <synopsis>Whether to add a 'line' parameter to the Contact for inbound call matching</synopsis>
                                        <description><para>
                                                When enabled this option will cause a 'line' parameter to be added to the Contact
                                                header placed into the outgoing registration request. If the remote server sends a call
                                                this line parameter will be used to establish a relationship to the outbound registration,
                                                ultimately causing the configured endpoint to be used.
                                        </para></description>
                                </configOption>
                                <configOption name="endpoint">
                                        <synopsis>Endpoint to use for incoming related calls</synopsis>
                                        <description><para>
                                                When line support is enabled this configured endpoint name is used for incoming calls
                                                that are related to the outbound registration.
                                        </para></description>
                                </configOption>
                                <configOption name="type">
                                        <synopsis>Must be of type 'registration'.</synopsis>
                                </configOption>
                                <configOption name="support_path">
                                        <synopsis>Enables advertising SIP Path support for outbound REGISTER requests.</synopsis>
                                        <description><para>
                                                When this option is enabled, outbound REGISTER requests will advertise
                                                support for Path headers so that intervening proxies can add to the Path
                                                header as necessary.
                                        </para></description>
                                </configOption>
                                <configOption name="support_outbound">
                                        <synopsis>Enables advertising SIP Outbound support (RFC5626) for outbound REGISTER requests.</synopsis>
                                </configOption>
                        </configObject>
                </configFile>
        </configInfo>
        <manager name="PJSIPUnregister" language="en_US">
                <synopsis>
                        Unregister an outbound registration.
                </synopsis>
                <syntax>
                        <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
                        <parameter name="Registration" required="true">
                                <para>The outbound registration to unregister or '*all' to unregister them all.</para>
                        </parameter>
                </syntax>
                <description>
                        <para>
                        Unregisters the specified (or all) outbound registration(s) and stops future registration attempts.
                        Call PJSIPRegister to start registration and schedule re-registrations according to configuration.
            </para>
                </description>
        </manager>
        <manager name="PJSIPRegister" language="en_US">
                <synopsis>
                        Register an outbound registration.
                </synopsis>
                <syntax>
                        <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
                        <parameter name="Registration" required="true">
                                <para>The outbound registration to register or '*all' to register them all.</para>
                        </parameter>
                </syntax>
                <description>
                        <para>
                        Unregisters the specified (or all) outbound registration(s) then starts registration and schedules re-registrations
                        according to configuration.
            </para>
                </description>
        </manager>
        <manager name="PJSIPShowRegistrationsOutbound" language="en_US">
                <synopsis>
                        Lists PJSIP outbound registrations.
                </synopsis>
                <syntax />
                <description>
                        <para>
                        In response <literal>OutboundRegistrationDetail</literal> events showing configuration and status
                        information are raised for each outbound registration object. <literal>AuthDetail</literal>
                        events are raised for each associated auth object as well.  Once all events are completed an
                        <literal>OutboundRegistrationDetailComplete</literal> is issued.
                        </para>
                </description>
        </manager>
 ***/

/* forward declarations */
static int set_outbound_initial_authentication_credentials(pjsip_regc *regc,
                const struct ast_sip_auth_vector *auth_vector);

/*! \brief Some thread local storage used to determine if the running thread invoked the callback */
AST_THREADSTORAGE(register_callback_invoked);

/*! \brief Amount of buffer time (in seconds) before expiration that we re-register at */
#define REREGISTER_BUFFER_TIME 10

/*! \brief Size of the buffer for creating a unique string for the line */
#define LINE_PARAMETER_SIZE 8

/*! \brief Various states that an outbound registration may be in */
enum sip_outbound_registration_status {
        /*! \brief Currently unregistered */
        SIP_REGISTRATION_UNREGISTERED = 0,
        /*! \brief Registered, yay! */
        SIP_REGISTRATION_REGISTERED,
        /*! \brief Registration was rejected, but response was temporal */
        SIP_REGISTRATION_REJECTED_TEMPORARY,
        /*! \brief Registration was rejected, permanently */
        SIP_REGISTRATION_REJECTED_PERMANENT,
        /*! \brief Registration is stopping. */
        SIP_REGISTRATION_STOPPING,
        /*! \brief Registration has been stopped */
        SIP_REGISTRATION_STOPPED,
};

/*!
 * \internal
 * \brief Convert the internal registration state to an external status string.
 * \since 13.5.0
 *
 * \param state Current outbound registration state.
 *
 * \return External registration status string.
 */
static const char *sip_outbound_registration_status_str(enum sip_outbound_registration_status state)
{
        const char *str;

        str = "Unregistered";
        switch (state) {
        case SIP_REGISTRATION_STOPPING:
        case SIP_REGISTRATION_STOPPED:
        case SIP_REGISTRATION_UNREGISTERED:
                break;
        case SIP_REGISTRATION_REGISTERED:
                str = "Registered";
                break;
        case SIP_REGISTRATION_REJECTED_TEMPORARY:
        case SIP_REGISTRATION_REJECTED_PERMANENT:
                str = "Rejected";
                break;
        }
        return str;
}

/*! \brief Outbound registration information */
struct sip_outbound_registration {
        /*! \brief Sorcery object details */
        SORCERY_OBJECT(details);
        /*! \brief Stringfields */
        AST_DECLARE_STRING_FIELDS(
                /*! \brief URI for the registrar */
                AST_STRING_FIELD(server_uri);
                /*! \brief URI for the AOR */
                AST_STRING_FIELD(client_uri);
                /*! \brief Optional user for contact header */
                AST_STRING_FIELD(contact_user);
                /*! \brief Optional header parameters for contact */
                AST_STRING_FIELD(contact_header_params);
                /*! \brief Explicit transport to use for registration */
                AST_STRING_FIELD(transport);
                /*! \brief Outbound proxy to use */
                AST_STRING_FIELD(outbound_proxy);
                /*! \brief Endpoint to use for related incoming calls */
                AST_STRING_FIELD(endpoint);
        );
        /*! \brief Requested expiration time */
        unsigned int expiration;
        /*! \brief Maximum random initial delay interval for initial registrations */
        unsigned int max_random_initial_delay;
        /*! \brief Interval at which retries should occur for temporal responses */
        unsigned int retry_interval;
        /*! \brief Interval at which retries should occur for permanent responses */
        unsigned int forbidden_retry_interval;
        /*! \brief Interval at which retries should occur for all permanent responses */
        unsigned int fatal_retry_interval;
        /*! \brief Treat authentication challenges that we cannot handle as permanent failures */
        unsigned int auth_rejection_permanent;
        /*! \brief Maximum number of retries permitted */
        unsigned int max_retries;
        /*! \brief Whether to add a line parameter to the outbound Contact or not */
        unsigned int line;
        /*! \brief Type of security negotiation to use (RFC 3329). */
        enum ast_sip_security_negotiation security_negotiation;
        /*! \brief Client security mechanisms (RFC 3329). */
        struct ast_sip_security_mechanism_vector security_mechanisms;
        /*! \brief Configured authentication credentials */
        struct ast_sip_auth_vector outbound_auths;
        /*! \brief Whether Path support is enabled */
        unsigned int support_path;
        /*! \brief Whether Outbound support is enabled */
        unsigned int support_outbound;
};

/*! \brief Outbound registration client state information (persists for lifetime of regc) */
struct sip_outbound_registration_client_state {
        /*! \brief Current state of this registration */
        enum sip_outbound_registration_status status;
        /*!
         * \brief Outbound registration client
         * \note May only be accessed within the serializer thread
         * because it might get destroyed and set to NULL for
         * module unload.
         */
        pjsip_regc *client;
        /*!
         * \brief Last tdata sent
         * We need the original tdata to resend a request on auth failure
         * or timeout.  On an auth failure, we use the original tdata
         * to initialize the new tdata for the authorized response.  On a timeout
         * we need it to skip failed SRV entries if any.
         */
        pjsip_tx_data *last_tdata;
        /*! \brief Timer entry for retrying on temporal responses */
        pj_timer_entry timer;
        /*! \brief Optional line parameter placed into Contact */
        char line[LINE_PARAMETER_SIZE];
        /*! \brief Current number of retries */
        unsigned int retries;
        /*! \brief Maximum number of retries permitted */
        unsigned int max_retries;
        /*! \brief Interval at which retries should occur for temporal responses */
        unsigned int retry_interval;
        /*! \brief Interval at which retries should occur for permanent responses */
        unsigned int forbidden_retry_interval;
        /*! \brief Interval at which retries should occur for all permanent responses */
        unsigned int fatal_retry_interval;
        /*! \brief Treat authentication challenges that we cannot handle as permanent failures */
        unsigned int auth_rejection_permanent;
        /*! \brief Determines whether SIP Path support should be advertised */
        unsigned int support_path;
        /*! \brief Determines whether SIP Outbound support should be advertised */
        unsigned int support_outbound;
        /*! \brief Type of security negotiation to use (RFC 3329). */
        enum ast_sip_security_negotiation security_negotiation;
        /*! \brief Client security mechanisms (RFC 3329). */
        struct ast_sip_security_mechanism_vector security_mechanisms;
        /*! \brief Security mechanisms of the peer (RFC 3329). */
        struct ast_sip_security_mechanism_vector server_security_mechanisms;
        /*! CSeq number of last sent auth request. */
        unsigned int auth_cseq;
        /*! \brief Serializer for stuff and things */
        struct ast_taskprocessor *serializer;
        /*! \brief Configured authentication credentials */
        struct ast_sip_auth_vector outbound_auths;
        /*! \brief Registration should be destroyed after completion of transaction */
        unsigned int destroy:1;
        /*! \brief Non-zero if we have attempted sending a REGISTER with authentication */
        unsigned int auth_attempted:1;
        /*! \brief Status code of last response if we have tried to register before */
        int last_status_code;
        /*! \brief The name of the transport to be used for the registration */
        char *transport_name;
        /*! \brief The name of the registration sorcery object */
        char *registration_name;
        /*! \brief Expected time of registration lapse/expiration */
        unsigned int registration_expires;
};

/*! \brief Outbound registration state information (persists for lifetime that registration should exist) */
struct sip_outbound_registration_state {
        /*! \brief Outbound registration configuration object */
        struct sip_outbound_registration *registration;
        /*! \brief Client state information */
        struct sip_outbound_registration_client_state *client_state;
};

/*! Time needs to be long enough for a transaction to timeout if nothing replies. */
#define MAX_UNLOAD_TIMEOUT_TIME         35      /* Seconds */

/*! Shutdown group to monitor sip_outbound_registration_client_state serializers. */
static struct ast_serializer_shutdown_group *shutdown_group;

/*! \brief Default number of state container buckets */
#define DEFAULT_STATE_BUCKETS 53
static AO2_GLOBAL_OBJ_STATIC(current_states);

/*! subscription id for network change events */
static struct stasis_subscription *network_change_sub;

/*! \brief hashing function for state objects */
static int registration_state_hash(const void *obj, const int flags)
{
        const struct sip_outbound_registration_state *object;
        const char *key;

        switch (flags & OBJ_SEARCH_MASK) {
        case OBJ_SEARCH_KEY:
                key = obj;
                break;
        case OBJ_SEARCH_OBJECT:
                object = obj;
                key = ast_sorcery_object_get_id(object->registration);
                break;
        default:
                ast_assert(0);
                return 0;
        }
        return ast_str_hash(key);
}

/*! \brief comparator function for state objects */
static int registration_state_cmp(void *obj, void *arg, int flags)
{
        const struct sip_outbound_registration_state *object_left = obj;
        const struct sip_outbound_registration_state *object_right = arg;
        const char *right_key = arg;
        int cmp;

        switch (flags & OBJ_SEARCH_MASK) {
        case OBJ_SEARCH_OBJECT:
                right_key = ast_sorcery_object_get_id(object_right->registration);
                /* Fall through */
        case OBJ_SEARCH_KEY:
                cmp = strcmp(ast_sorcery_object_get_id(object_left->registration), right_key);
                break;
        case OBJ_SEARCH_PARTIAL_KEY:
                /* Not supported by container. */
                ast_assert(0);
                return 0;
        default:
                cmp = 0;
                break;
        }
        if (cmp) {
                return 0;
        }
        return CMP_MATCH;
}

static struct sip_outbound_registration_state *get_state(const char *id)
{
        struct sip_outbound_registration_state *state = NULL;
        struct ao2_container *states;

        states = ao2_global_obj_ref(current_states);
        if (states) {
                state = ao2_find(states, id, OBJ_SEARCH_KEY);
                ao2_ref(states, -1);
        }
        return state;
}

static struct ao2_container *get_registrations(void)
{
        struct ao2_container *registrations = ast_sorcery_retrieve_by_fields(
                ast_sip_get_sorcery(), "registration",
                AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);

        return registrations;
}

/*! \brief Callback function for matching an outbound registration based on line */
static int line_identify_relationship(void *obj, void *arg, int flags)
{
        struct sip_outbound_registration_state *state = obj;
        pjsip_param *line = arg;

        return !pj_strcmp2(&line->value, state->client_state->line) ? CMP_MATCH : 0;
}

static struct pjsip_param *get_uri_option_line(const void *uri)
{
        static const pj_str_t LINE_STR = { "line", 4 };

        return ast_sip_pjsip_uri_get_other_param((pjsip_uri *)uri, &LINE_STR);
}

/*! \brief Endpoint identifier which uses the 'line' parameter to establish a relationship to an outgoing registration */
static struct ast_sip_endpoint *line_identify(pjsip_rx_data *rdata)
{
        pjsip_param *line;
        RAII_VAR(struct ao2_container *, states, NULL, ao2_cleanup);
        RAII_VAR(struct sip_outbound_registration_state *, state, NULL, ao2_cleanup);

        if (!(line = get_uri_option_line(rdata->msg_info.to->uri))
                && !(line = get_uri_option_line(rdata->msg_info.msg->line.req.uri))) {
                return NULL;
        }

        states = ao2_global_obj_ref(current_states);
        if (!states) {
                return NULL;
        }

        state = ao2_callback(states, 0, line_identify_relationship, line);
        if (!state || ast_strlen_zero(state->registration->endpoint)) {
                return NULL;
        }

        ast_debug(3, "Determined relationship to outbound registration '%s' based on line '%s', using configured endpoint '%s'\n",
                ast_sorcery_object_get_id(state->registration), state->client_state->line, state->registration->endpoint);

        return ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "endpoint", state->registration->endpoint);
}

static struct ast_sip_endpoint_identifier line_identifier = {
        .identify_endpoint = line_identify,
};

/*! \brief Helper function which cancels the timer on a client */
static void cancel_registration(struct sip_outbound_registration_client_state *client_state)
{
        if (pj_timer_heap_cancel_if_active(pjsip_endpt_get_timer_heap(ast_sip_get_pjsip_endpoint()),
                &client_state->timer, client_state->timer.id)) {
                /* The timer was successfully cancelled, drop the refcount of client_state */
                ao2_ref(client_state, -1);
        }
}

static pj_str_t PATH_NAME = { "path", 4 };
static pj_str_t OUTBOUND_NAME = { "outbound", 8 };

AST_VECTOR(pjsip_generic_string_hdr_vector, pjsip_generic_string_hdr *);

/*!
 * \internal
 * \brief Callback function which finds a contact whose contact_status has security mechanisms.
 *
 * \param obj Pointer to the ast_sip_contact.
 * \param arg Pointer-pointer to a contact_status that will be set to the contact_status found by this function.
 * \param flags Flags used by the ao2_callback function.
 *
 * \note The refcount of the found contact_status must be decremented by the caller.
 */
static int contact_has_security_mechanisms(void *obj, void *arg, int flags)
{
        struct ast_sip_contact *contact = obj;
        struct ast_sip_contact_status **ret = arg;
        struct ast_sip_contact_status *contact_status = ast_sip_get_contact_status(contact);

        if (!contact_status) {
                return -1;
        }
        if (!AST_VECTOR_SIZE(&contact_status->security_mechanisms)) {
                ao2_cleanup(contact_status);
                return -1;
        }
        *ret = contact_status;
        return 0;
}

static int contact_add_security_headers_to_status(void *obj, void *arg, int flags)
{
        struct ast_sip_contact *contact = obj;
        struct pjsip_generic_string_hdr_vector *header_vector = arg;
        struct ast_sip_contact_status *contact_status = ast_sip_get_contact_status(contact);

        if (!contact_status) {
                return -1;
        }
        if (AST_VECTOR_SIZE(&contact_status->security_mechanisms)) {
                goto out;
        }

        ao2_lock(contact_status);
        AST_VECTOR_CALLBACK_VOID(header_vector, ast_sip_header_to_security_mechanism, &contact_status->security_mechanisms);
        ao2_unlock(contact_status);

out:
        ao2_cleanup(contact_status);
        return 0;
}

/*! \brief Adds security negotiation mechanisms of outbound registration client state as Security headers to tdata. */
static void add_security_headers(struct sip_outbound_registration_client_state *client_state,
        pjsip_tx_data *tdata)
{
        int add_require_header = 1;
        int add_proxy_require_header = 1;
        int add_sec_client_header = 0;
        struct sip_outbound_registration *reg = NULL;
        struct ast_sip_endpoint *endpt = NULL;
        struct ao2_container *contact_container;
        struct ast_sip_contact_status *contact_status = NULL;
        struct ast_sip_security_mechanism_vector *sec_mechs = NULL;
        static const pj_str_t security_verify = { "Security-Verify", 15 };
        static const pj_str_t security_client = { "Security-Client", 15 };
        static const pj_str_t proxy_require = { "Proxy-Require", 13 };
        static const pj_str_t require = { "Require", 7 };

        if (client_state->security_negotiation != AST_SIP_SECURITY_NEG_MEDIASEC) {
                return;
        }

        /* Get contact status through registration -> endpoint name -> aor -> contact (if set) */
        if ((reg = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "registration", client_state->registration_name))
                && !ast_strlen_zero(reg->endpoint) && (endpt = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "endpoint", reg->endpoint))
                && (contact_container = ast_sip_location_retrieve_contacts_from_aor_list(endpt->aors))) {
                /* Retrieve all contacts associated with aors from this endpoint
                 * and find the first one that has security mechanisms.
                 */
                ao2_callback(contact_container, 0, contact_has_security_mechanisms, &contact_status);
                if (contact_status) {
                        ao2_lock(contact_status);
                        sec_mechs = &contact_status->security_mechanisms;
                }
                ao2_cleanup(contact_container);
        }
        /* Use client_state->server_security_mechanisms if contact_status does not exist. */
        if (!contact_status && AST_VECTOR_SIZE(&client_state->server_security_mechanisms)) {
                sec_mechs = &client_state->server_security_mechanisms;
        }
        if (client_state->status == SIP_REGISTRATION_REJECTED_TEMPORARY || client_state->auth_attempted) {
                if (sec_mechs != NULL && pjsip_msg_find_hdr_by_name(tdata->msg, &security_verify, NULL) == NULL) {
                        ast_sip_add_security_headers(sec_mechs, "Security-Verify", 0, tdata);
                }
                if (client_state->last_status_code == 494) {
                        ast_sip_remove_headers_by_name_and_value(tdata->msg, &security_client, NULL);
                } else {
                        /* necessary if a retry occures */
                        add_sec_client_header = (pjsip_msg_find_hdr_by_name(tdata->msg, &security_client, NULL) == NULL) ? 1 : 0;
                }
                add_require_header =
                        (pjsip_msg_find_hdr_by_name(tdata->msg, &require, NULL) == NULL) ? 1 : 0;
                add_proxy_require_header =
                        (pjsip_msg_find_hdr_by_name(tdata->msg, &proxy_require, NULL) == NULL) ? 1 : 0;
        } else {
                ast_sip_add_security_headers(&client_state->security_mechanisms, "Security-Client", 0, tdata);
        }

        if (add_require_header) {
                ast_sip_add_header(tdata, "Require", "mediasec");
        }
        if (add_proxy_require_header) {
                ast_sip_add_header(tdata, "Proxy-Require", "mediasec");
        }
        if (add_sec_client_header) {
                ast_sip_add_security_headers(&client_state->security_mechanisms, "Security-Client", 0, tdata);
        }

        /* Cleanup */
        if (contact_status) {
                ao2_unlock(contact_status);
                ao2_cleanup(contact_status);
        }
        ao2_cleanup(endpt);
        ao2_cleanup(reg);
}

/*! \brief Helper function which sends a message and cleans up, if needed, on failure */
static pj_status_t registration_client_send(struct sip_outbound_registration_client_state *client_state,
        pjsip_tx_data *tdata)
{
        pj_status_t status;
        int *callback_invoked;
        pjsip_tpselector selector = { .type = PJSIP_TPSELECTOR_NONE, };

        callback_invoked = ast_threadstorage_get(&register_callback_invoked, sizeof(int));
        if (!callback_invoked) {
                pjsip_tx_data_dec_ref(tdata);
                return PJ_ENOMEM;
        }
        *callback_invoked = 0;

        /* Due to the message going out the callback may now be invoked, so bump the count */
        ao2_ref(client_state, +1);
        /*
         * We also bump tdata in expectation of saving it to client_state->last_tdata.
         * We have to do it BEFORE pjsip_regc_send because if it succeeds, it decrements
         * the ref count on its own.
         */
        pjsip_tx_data_add_ref(tdata);

        /* Add Security-Verify or Security-Client headers */
        add_security_headers(client_state, tdata);

        /*
         * Set the transport in case transports were reloaded.
         * When pjproject removes the extraneous error messages produced,
         * we can check status and only set the transport and resend if there was an error
         */
        ast_sip_set_tpselector_from_transport_name(client_state->transport_name, &selector);
        pjsip_regc_set_transport(client_state->client, &selector);
        ast_sip_tpselector_unref(&selector);

        status = pjsip_regc_send(client_state->client, tdata);

        /*
         * If the attempt to send the message failed and the callback was not invoked we need to
         * drop the references we just added
         */
        if ((status != PJ_SUCCESS) && !(*callback_invoked)) {
                pjsip_tx_data_dec_ref(tdata);
                ao2_ref(client_state, -1);
                return status;
        }

        /*
         * Decref the old last_data before replacing it.
         * BTW, it's quite possible that last_data == tdata
         * if we're trying successive servers in an SRV set.
         */
        if (client_state->last_tdata) {
                pjsip_tx_data_dec_ref(client_state->last_tdata);
        }
        client_state->last_tdata = tdata;

        return status;
}

/*! \brief Helper function to add string to Supported header */
static int add_to_supported_header(pjsip_tx_data *tdata, pj_str_t *name)
{
        pjsip_supported_hdr *hdr;
        int i;

        hdr = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_SUPPORTED, NULL);
        if (!hdr) {
                /* insert a new Supported header */
                hdr = pjsip_supported_hdr_create(tdata->pool);
                if (!hdr) {
                        pjsip_tx_data_dec_ref(tdata);
                        return 0;
                }

                pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)hdr);
        }

        /* Don't add the value if it's already there */
        for (i = 0; i < hdr->count; ++i) {
                if (pj_stricmp(&hdr->values[i], name) == 0) {
                        return 1;
                }
        }

        if (hdr->count >= PJSIP_GENERIC_ARRAY_MAX_COUNT) {
                return 0;
        }

        /* add on to the existing Supported header */
        pj_strassign(&hdr->values[hdr->count++], name);

        return 1;
}

/*! \brief Helper function to add configured supported headers */
static int add_configured_supported_headers(struct sip_outbound_registration_client_state *client_state, pjsip_tx_data *tdata)
{
        if (client_state->support_path) {
                if (!add_to_supported_header(tdata, &PATH_NAME)) {
                        return 0;
                }
        }

        if (client_state->support_outbound) {
                if (!add_to_supported_header(tdata, &OUTBOUND_NAME)) {
                        return 0;
                }
        }

        return 1;
}

/*! \brief Callback function for registering */
static int handle_client_registration(void *data)
{
        RAII_VAR(struct sip_outbound_registration_client_state *, client_state, data, ao2_cleanup);
        pjsip_tx_data *tdata;

        if (set_outbound_initial_authentication_credentials(client_state->client, &client_state->outbound_auths)) {
                ast_log(LOG_WARNING, "Failed to set initial authentication credentials\n");
        }

        if (client_state->status == SIP_REGISTRATION_STOPPED
                || pjsip_regc_register(client_state->client, PJ_FALSE, &tdata) != PJ_SUCCESS) {
                return 0;
        }

        if (DEBUG_ATLEAST(1)) {
                pjsip_regc_info info;

                pjsip_regc_get_info(client_state->client, &info);
                ast_log(LOG_DEBUG, "Outbound REGISTER attempt %u to '%.*s' with client '%.*s'\n",
                        client_state->retries + 1,
                        (int) info.server_uri.slen, info.server_uri.ptr,
                        (int) info.client_uri.slen, info.client_uri.ptr);
        }

        if (!add_configured_supported_headers(client_state, tdata)) {
                ast_log(LOG_WARNING, "Failed to set supported headers\n");
                return -1;
        }

        registration_client_send(client_state, tdata);

        return 0;
}

/*! \brief Timer callback function, used just for registrations */
static void sip_outbound_registration_timer_cb(pj_timer_heap_t *timer_heap, struct pj_timer_entry *entry)
{
        struct sip_outbound_registration_client_state *client_state = entry->user_data;

        entry->id = 0;

        /*
         * Transfer client_state reference to serializer task so the
         * nominal path will not dec the client_state ref in this
         * pjproject callback thread.
         */
        if (ast_sip_push_task(client_state->serializer, handle_client_registration, client_state)) {
                ast_log(LOG_WARNING, "Scheduled outbound registration could not be executed.\n");
                ao2_ref(client_state, -1);
        }
}

/*! \brief Helper function which sets up the timer to re-register in a specific amount of time */
static void schedule_registration(struct sip_outbound_registration_client_state *client_state, unsigned int seconds)
{
        pj_time_val delay = { .sec = seconds, };
        pjsip_regc_info info;

        cancel_registration(client_state);

        pjsip_regc_get_info(client_state->client, &info);
        ast_debug(1, "Scheduling outbound registration to server '%.*s' from client '%.*s' in %d seconds\n",
                        (int) info.server_uri.slen, info.server_uri.ptr,
                        (int) info.client_uri.slen, info.client_uri.ptr,
                        seconds);

        ao2_ref(client_state, +1);
        if (pjsip_endpt_schedule_timer(ast_sip_get_pjsip_endpoint(), &client_state->timer, &delay) != PJ_SUCCESS) {
                ast_log(LOG_WARNING, "Failed to schedule registration to server '%.*s' from client '%.*s'\n",
                                (int) info.server_uri.slen, info.server_uri.ptr,
                                (int) info.client_uri.slen, info.client_uri.ptr);
                ao2_ref(client_state, -1);
        }
        client_state->registration_expires = ((int) time(NULL)) + seconds;
}

static void update_client_state_status(struct sip_outbound_registration_client_state *client_state, enum sip_outbound_registration_status status)
{
        const char *status_old;
        const char *status_new;

        if (client_state->status == status) {
                /* Status state did not change at all. */
                return;
        }

        status_old = sip_outbound_registration_status_str(client_state->status);
        status_new = sip_outbound_registration_status_str(status);
        client_state->status = status;

        if (!strcmp(status_old, status_new)) {
                /*
                 * The internal status state may have changed but the status
                 * state we tell the world did not change at all.
                 */
                return;
        }

        ast_statsd_log_string_va("PJSIP.registrations.state.%s", AST_STATSD_GAUGE, "-1", 1.0,
                status_old);
        ast_statsd_log_string_va("PJSIP.registrations.state.%s", AST_STATSD_GAUGE, "+1", 1.0,
                status_new);
}

/*! \brief Callback function for unregistering (potentially) and destroying state */
static int handle_client_state_destruction(void *data)
{
        struct sip_outbound_registration_client_state *client_state = data;

        cancel_registration(client_state);

        if (client_state->client) {
                pjsip_regc_info info;
                pjsip_tx_data *tdata;

                pjsip_regc_get_info(client_state->client, &info);

                if (info.is_busy == PJ_TRUE) {
                        /* If a client transaction is in progress we defer until it is complete */
                        ast_debug(1,
                                "Registration transaction is busy with server '%.*s' from client '%.*s'.\n",
                                (int) info.server_uri.slen, info.server_uri.ptr,
                                (int) info.client_uri.slen, info.client_uri.ptr);
                        client_state->destroy = 1;
                        ao2_ref(client_state, -1);
                        return 0;
                }

                switch (client_state->status) {
                case SIP_REGISTRATION_UNREGISTERED:
                        break;
                case SIP_REGISTRATION_REGISTERED:
                        ast_debug(1,
                                "Trying to unregister with server '%.*s' from client '%.*s' before destruction.\n",
                                (int) info.server_uri.slen, info.server_uri.ptr,
                                (int) info.client_uri.slen, info.client_uri.ptr);

                        update_client_state_status(client_state, SIP_REGISTRATION_STOPPING);
                        client_state->destroy = 1;
                        if (pjsip_regc_unregister(client_state->client, &tdata) == PJ_SUCCESS
                                && add_configured_supported_headers(client_state, tdata)
                                && registration_client_send(client_state, tdata) == PJ_SUCCESS) {
                                ao2_ref(client_state, -1);
                                return 0;
                        }
                        break;
                case SIP_REGISTRATION_REJECTED_TEMPORARY:
                case SIP_REGISTRATION_REJECTED_PERMANENT:
                case SIP_REGISTRATION_STOPPING:
                case SIP_REGISTRATION_STOPPED:
                        break;
                }

                pjsip_regc_destroy(client_state->client);
                client_state->client = NULL;
        }

        update_client_state_status(client_state, SIP_REGISTRATION_STOPPED);
        ast_sip_auth_vector_destroy(&client_state->outbound_auths);
        ast_sip_security_mechanisms_vector_destroy(&client_state->security_mechanisms);
        ast_sip_security_mechanisms_vector_destroy(&client_state->server_security_mechanisms);
        ao2_ref(client_state, -1);

        return 0;
}

/*! \brief Structure for registration response */
struct registration_response {
        /*! \brief Response code for the registration attempt */
        int code;
        /*! \brief Expiration time for registration */
        int expiration;
        /*! \brief Retry-After value */
        int retry_after;
        /*! \brief Outbound registration client state */
        struct sip_outbound_registration_client_state *client_state;
        /*! \brief The response message */
        pjsip_rx_data *rdata;
        /*! \brief Request for which the response was received */
        pjsip_tx_data *old_request;
        /*! \brief Key for the reliable transport in use */
        char transport_key[IP6ADDR_COLON_PORT_BUFLEN];
};

/*! \brief Registration response structure destructor */
static void registration_response_destroy(void *obj)
{
        struct registration_response *response = obj;

        if (response->rdata) {
                pjsip_rx_data_free_cloned(response->rdata);
        }

        if (response->old_request) {
                pjsip_tx_data_dec_ref(response->old_request);
        }

        ao2_cleanup(response->client_state);
}

/*! \brief Helper function which determines if a response code is temporal or not */
static int sip_outbound_registration_is_temporal(unsigned int code,
                struct sip_outbound_registration_client_state *client_state)
{
        /* Shamelessly taken from pjsua */
        if (code == PJSIP_SC_REQUEST_TIMEOUT ||
                code == PJSIP_SC_INTERNAL_SERVER_ERROR ||
                code == PJSIP_SC_BAD_GATEWAY ||
                code == PJSIP_SC_SERVICE_UNAVAILABLE ||
                code == PJSIP_SC_SERVER_TIMEOUT ||
                ((code == PJSIP_SC_UNAUTHORIZED ||
                  code == PJSIP_SC_PROXY_AUTHENTICATION_REQUIRED) &&
                 !client_state->auth_rejection_permanent) ||
                PJSIP_IS_STATUS_IN_CLASS(code, 600)) {
                return 1;
        } else {
                return 0;
        }
}

static void schedule_retry(struct registration_response *response, unsigned int interval,
                           const char *server_uri, const char *client_uri)
{
        update_client_state_status(response->client_state, SIP_REGISTRATION_REJECTED_TEMPORARY);
        schedule_registration(response->client_state, interval);

        if (response->rdata) {
                ast_log(LOG_WARNING, "Temporal response '%d' received from '%s' on "
                        "registration attempt to '%s', retrying in '%u'\n",
                        response->code, server_uri, client_uri, interval);
        } else {
                ast_log(LOG_WARNING, "No response received from '%s' on "
                        "registration attempt to '%s', retrying in '%u'\n",
                        server_uri, client_uri, interval);
        }
}

static int reregister_immediately_cb(void *obj)
{
        struct sip_outbound_registration_state *state = obj;

        if (state->client_state->status != SIP_REGISTRATION_REGISTERED) {
                ao2_ref(state, -1);
                return 0;
        }

        if (DEBUG_ATLEAST(1)) {
                pjsip_regc_info info;

                pjsip_regc_get_info(state->client_state->client, &info);
                ast_log(LOG_DEBUG,
                        "Outbound registration transport to server '%.*s' from client '%.*s' shutdown\n",
                        (int) info.server_uri.slen, info.server_uri.ptr,
                        (int) info.client_uri.slen, info.client_uri.ptr);
        }

        cancel_registration(state->client_state);

        ao2_ref(state->client_state, +1);
        handle_client_registration(state->client_state);

        ao2_ref(state, -1);
        return 0;
}

/*!
 * \internal
 * \brief The reliable transport we registered using has shutdown.
 * \since 13.18.0
 *
 * \param obj What is needed to initiate a reregister attempt.
 *
 * \note Normally executed by the pjsip monitor thread.
 */
static void registration_transport_shutdown_cb(void *obj)
{
        const char *registration_name = obj;
        struct sip_outbound_registration_state *state;

        state = get_state(registration_name);
        if (!state) {
                /* Registration no longer exists or shutting down. */
                return;
        }
        if (ast_sip_push_task(state->client_state->serializer, reregister_immediately_cb, state)) {
                ao2_ref(state, -1);
        }
}

static int monitor_matcher(void *a, void *b)
{
        char *ma = a;
        char *mb = b;

        return strcmp(ma, mb) == 0;
}

static void registration_transport_monitor_setup(const char *transport_key, const char *registration_name)
{
        char *monitor;

        monitor = ao2_alloc_options(strlen(registration_name) + 1, NULL,
                AO2_ALLOC_OPT_LOCK_NOLOCK);
        if (!monitor) {
                return;
        }
        strcpy(monitor, registration_name);/* Safe */

        /*
         * We'll ignore if the transport has already been shutdown before we
         * register the monitor.  We might get into a message spamming infinite
         * loop of registration, shutdown, reregistration...
         */
        ast_sip_transport_monitor_register_replace_key(transport_key, registration_transport_shutdown_cb,
                monitor, monitor_matcher);
        ao2_ref(monitor, -1);
}

static void save_response_fields_to_transport(struct registration_response *response)
{
        static const pj_str_t associated_uri_str = { "P-Associated-URI", 16 };
        static const pj_str_t service_route_str = { "Service-Route", 13 };
        pjsip_hdr *header = NULL;
        pjsip_msg *msg = response->rdata->msg_info.msg;
        struct ast_sip_service_route_vector *service_routes = NULL;

        /* If no transport is specified then we can't update any */
        if (ast_strlen_zero(response->client_state->transport_name)) {
                return;
        }

        ast_sip_transport_state_set_transport(response->client_state->transport_name, response->rdata->tp_info.transport);

        while ((header = pjsip_msg_find_hdr_by_name(msg, &service_route_str, header ? header->next : NULL))) {
                char *service_route;
                size_t size;

                /* The below code takes the approach that if we can't store all service routes then we
                 * store none at all. This gives a predictable failure condition instead of storing a
                 * partial list and having partial route headers.
                 */
                size = pj_strlen(&((pjsip_generic_string_hdr*)header)->hvalue) + 1;
                service_route = ast_malloc(size);
                if (!service_route) {
                        if (service_routes) {
                                ast_sip_service_route_vector_destroy(service_routes);
                                service_routes = NULL;
                        }
                        break;
                }

                ast_copy_pj_str(service_route, &((pjsip_generic_string_hdr*)header)->hvalue, size);

                if (!service_routes) {
                        service_routes = ast_sip_service_route_vector_alloc();
                        if (!service_routes) {
                                ast_free(service_route);
                                break;
                        }
                }

                if (AST_VECTOR_APPEND(service_routes, service_route)) {
                        ast_free(service_route);
                        ast_sip_service_route_vector_destroy(service_routes);
                        service_routes = NULL;
                        break;
                }
        }

        /* If any service routes were handled then store them on the transport */
        if (service_routes) {
                ast_sip_transport_state_set_service_routes(response->client_state->transport_name, service_routes);
        }

        /* If an associated URI is present in the response we need to use it on any outgoing
         * traffic on the transport.
         */
        header = pjsip_msg_find_hdr_by_name(msg, &associated_uri_str, NULL);
        if (header) {
                char value[pj_strlen(&((pjsip_generic_string_hdr*)header)->hvalue) + 1];

                ast_copy_pj_str(value, &((pjsip_generic_string_hdr*)header)->hvalue, sizeof(value));
                ast_sip_transport_state_set_preferred_identity(response->client_state->transport_name, value);
        }
}


/*! \brief Callback function for handling a response to a registration attempt */
static int handle_registration_response(void *data)
{
        struct registration_response *response = data;
        pjsip_regc_info info;
        char server_uri[PJSIP_MAX_URL_SIZE];
        char client_uri[PJSIP_MAX_URL_SIZE];

        if (response->client_state->status == SIP_REGISTRATION_STOPPED) {
                ao2_ref(response, -1);
                return 0;
        }

        pjsip_regc_get_info(response->client_state->client, &info);
        ast_copy_pj_str(server_uri, &info.server_uri, sizeof(server_uri));
        ast_copy_pj_str(client_uri, &info.client_uri, sizeof(client_uri));
        response->client_state->last_status_code = response->code;

        ast_debug(1, "Processing REGISTER response %d from server '%s' for client '%s'\n",
                        response->code, server_uri, client_uri);

        if (response->code == 408 || response->code == 503) {
                if ((ast_sip_failover_request(response->old_request))) {
                        int res = registration_client_send(response->client_state, response->old_request);
                        /* The tdata ref was stolen */
                        response->old_request = NULL;
                        if (res == PJ_SUCCESS) {
                                ao2_ref(response, -1);
                                return 0;
                        }
                }
        } else if ((response->code == 401 || response->code == 407 || response->code == 494)
                && (!response->client_state->auth_attempted
                        || response->rdata->msg_info.cseq->cseq != response->client_state->auth_cseq)) {
                int res;
                pjsip_cseq_hdr *cseq_hdr;
                pjsip_tx_data *tdata;

                if (response->client_state->security_negotiation == AST_SIP_SECURITY_NEG_MEDIASEC) {
                        struct sip_outbound_registration *reg = NULL;
                        struct ast_sip_endpoint *endpt = NULL;
                        struct ao2_container *contact_container = NULL;
                        pjsip_generic_string_hdr *header;
                        struct pjsip_generic_string_hdr_vector header_vector;
                        static const pj_str_t security_server = { "Security-Server", 15 };

                        if ((reg = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "registration",
                                response->client_state->registration_name)) && reg->endpoint &&
                                (endpt = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "endpoint", reg->endpoint))) {
                                /* Retrieve all contacts associated with aors from this endpoint (if set). */
                                contact_container = ast_sip_location_retrieve_contacts_from_aor_list(endpt->aors);
                        }
                        /* Add server list of security mechanism to client_state and contact status if exists. */
                        AST_VECTOR_INIT(&header_vector, 1);
                        header = pjsip_msg_find_hdr_by_name(response->rdata->msg_info.msg, &security_server, NULL);
                        for (; header;
                                header = pjsip_msg_find_hdr_by_name(response->rdata->msg_info.msg, &security_server, header->next)) {
                                AST_VECTOR_APPEND(&header_vector, header);
                                ast_sip_header_to_security_mechanism(header, &response->client_state->server_security_mechanisms);
                        }
                        if (contact_container) {
                                /* Add server security mechanisms to contact status of all associated contacts to be able to send correct
                                 * Security-Verify headers on subsequent non-REGISTER requests through this outbound registration.
                                 */
                                ao2_callback(contact_container, OBJ_NODATA, contact_add_security_headers_to_status, &header_vector);
                                ao2_cleanup(contact_container);
                        }
                        AST_VECTOR_FREE(&header_vector);
                        ao2_cleanup(endpt);
                        ao2_cleanup(reg);
                }

                if (response->code == 494) {
                        update_client_state_status(response->client_state, SIP_REGISTRATION_REJECTED_TEMPORARY);
                        response->client_state->retries++;
                        schedule_registration(response->client_state, 0);
                        ao2_ref(response, -1);
                        return 0;
                } else if (!ast_sip_create_request_with_auth(&response->client_state->outbound_auths,
                                response->rdata, response->old_request, &tdata)) {
                        response->client_state->auth_attempted = 1;
                        ast_debug(1, "Sending authenticated REGISTER to server '%s' from client '%s'\n",
                                        server_uri, client_uri);
                        pjsip_tx_data_add_ref(tdata);

                        res = registration_client_send(response->client_state, tdata);

                        /* Save the cseq that actually got sent. */
                        cseq_hdr = (pjsip_cseq_hdr *) pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CSEQ,
                                NULL);
                        response->client_state->auth_cseq = cseq_hdr->cseq;
                        pjsip_tx_data_dec_ref(tdata);
                        if (res == PJ_SUCCESS) {
                                ao2_ref(response, -1);
                                return 0;
                        }
                } else {
                        ast_log(LOG_WARNING, "Failed to create authenticated REGISTER request to server '%s' from client '%s'\n",
                                        server_uri, client_uri);
                }
                /* Otherwise, fall through so the failure is processed appropriately */
        }

        response->client_state->auth_attempted = 0;

        if (PJSIP_IS_STATUS_IN_CLASS(response->code, 200)) {
                /* Check if this is in regards to registering or unregistering */
                if (response->expiration) {
                        int next_registration_round;

                        /* If the registration went fine simply reschedule registration for the future */
                        ast_debug(1, "Outbound registration to '%s' with client '%s' successful\n", server_uri, client_uri);
                        update_client_state_status(response->client_state, SIP_REGISTRATION_REGISTERED);
                        response->client_state->retries = 0;
                        next_registration_round = response->expiration - REREGISTER_BUFFER_TIME;
                        if (next_registration_round < 0) {
                                /* Re-register immediately. */
                                next_registration_round = 0;
                        }
                        schedule_registration(response->client_state, next_registration_round);

                        /* See if we should monitor for transport shutdown */
                        if (PJSIP_TRANSPORT_IS_RELIABLE(response->rdata->tp_info.transport)) {
                                registration_transport_monitor_setup(response->transport_key,
                                        response->client_state->registration_name);
                        }
                } else {
                        ast_debug(1, "Outbound unregistration to '%s' with client '%s' successful\n", server_uri, client_uri);
                        update_client_state_status(response->client_state, SIP_REGISTRATION_UNREGISTERED);
                        if (PJSIP_TRANSPORT_IS_RELIABLE(response->rdata->tp_info.transport)) {
                                ast_sip_transport_monitor_unregister_key(response->transport_key,
                                        registration_transport_shutdown_cb, response->client_state->registration_name,
                                        monitor_matcher);
                        }
                }

                save_response_fields_to_transport(response);
        } else if (response->client_state->destroy) {
                /* We need to deal with the pending destruction instead. */
        } else if (response->retry_after) {
                /* If we have been instructed to retry after a period of time, schedule it as such */
                schedule_retry(response, response->retry_after, server_uri, client_uri);
        } else if (response->client_state->retry_interval
                && sip_outbound_registration_is_temporal(response->code, response->client_state)) {
                if (response->client_state->retries == response->client_state->max_retries) {
                        /* If we received enough temporal responses to exceed our maximum give up permanently */
                        update_client_state_status(response->client_state, SIP_REGISTRATION_REJECTED_PERMANENT);
                        ast_log(LOG_WARNING, "Maximum retries reached when attempting outbound registration to '%s' with client '%s', stopping registration attempt\n",
                                server_uri, client_uri);
                } else {
                        /* On the other hand if we can still try some more do so */
                        response->client_state->retries++;
                        schedule_retry(response, response->client_state->retry_interval, server_uri, client_uri);
                }
        } else {
                if (response->code == 403
                        && response->client_state->forbidden_retry_interval
                        && response->client_state->retries < response->client_state->max_retries) {
                        /* A forbidden response retry interval is configured and there are retries remaining */
                        update_client_state_status(response->client_state, SIP_REGISTRATION_REJECTED_TEMPORARY);
                        response->client_state->retries++;
                        schedule_registration(response->client_state, response->client_state->forbidden_retry_interval);
                        ast_log(LOG_WARNING, "403 Forbidden fatal response received from '%s' on registration attempt to '%s', retrying in '%u' seconds\n",
                                server_uri, client_uri, response->client_state->forbidden_retry_interval);
                } else if (response->client_state->fatal_retry_interval
                           && response->client_state->retries < response->client_state->max_retries) {
                        /* Some kind of fatal failure response received, so retry according to configured interval */
                        update_client_state_status(response->client_state, SIP_REGISTRATION_REJECTED_TEMPORARY);
                        response->client_state->retries++;
                        schedule_registration(response->client_state, response->client_state->fatal_retry_interval);
                        ast_log(LOG_WARNING, "'%d' fatal response received from '%s' on registration attempt to '%s', retrying in '%u' seconds\n",
                                response->code, server_uri, client_uri, response->client_state->fatal_retry_interval);
                } else {
                        /* Finally if there's no hope of registering give up */
                        update_client_state_status(response->client_state, SIP_REGISTRATION_REJECTED_PERMANENT);
                        if (response->rdata) {
                                ast_log(LOG_WARNING, "Fatal response '%d' received from '%s' on registration attempt to '%s', stopping outbound registration\n",
                                        response->code, server_uri, client_uri);
                        } else {
                                ast_log(LOG_WARNING, "Fatal registration attempt to '%s', stopping outbound registration\n", client_uri);
                        }
                }
        }

        ast_system_publish_registry("PJSIP", client_uri, server_uri,
                sip_outbound_registration_status_str(response->client_state->status), NULL);

        if (response->client_state->destroy) {
                /* We have a pending deferred destruction to complete now. */
                ao2_ref(response->client_state, +1);
                handle_client_state_destruction(response->client_state);
        }

        ao2_ref(response, -1);
        return 0;
}

/*! \brief Callback function for outbound registration client */
static void sip_outbound_registration_response_cb(struct pjsip_regc_cbparam *param)
{
        struct sip_outbound_registration_client_state *client_state = param->token;
        struct registration_response *response;
        int *callback_invoked;

        callback_invoked = ast_threadstorage_get(&register_callback_invoked, sizeof(int));

        ast_assert(callback_invoked != NULL);
        ast_assert(client_state != NULL);

        *callback_invoked = 1;

        response = ao2_alloc(sizeof(*response), registration_response_destroy);
        if (!response) {
                ao2_ref(client_state, -1);
                return;
        }
        response->code = param->code;
        response->expiration = param->expiration;
        /*
         * Transfer client_state reference to response so the
         * nominal path will not dec the client_state ref in this
         * pjproject callback thread.
         */
        response->client_state = client_state;

        ast_debug(1, "Received REGISTER response %d(%.*s)\n",
                param->code, (int) param->reason.slen, param->reason.ptr);

        if (param->rdata) {
                struct pjsip_retry_after_hdr *retry_after;
                pjsip_transaction *tsx;

                retry_after = pjsip_msg_find_hdr(param->rdata->msg_info.msg, PJSIP_H_RETRY_AFTER,
                        NULL);
                response->retry_after = retry_after ? retry_after->ivalue : 0;

                /*
                 * If we got a response from the server, we have to use the tdata
                 * from the transaction, not the tdata saved when we sent the
                 * request.  If we use the saved tdata, we won't process responses
                 * like 423 Interval Too Brief correctly and we'll wind up sending
                 * the bad Expires value again.
                 */
                pjsip_tx_data_dec_ref(client_state->last_tdata);

                tsx = pjsip_rdata_get_tsx(param->rdata);
                response->old_request = tsx->last_tx;
                pjsip_tx_data_add_ref(response->old_request);
                pjsip_rx_data_clone(param->rdata, 0, &response->rdata);
                AST_SIP_MAKE_REMOTE_IPADDR_PORT_STR(param->rdata->tp_info.transport,
                        response->transport_key);

        } else {
                /* old_request steals the reference */
                response->old_request = client_state->last_tdata;
        }
        client_state->last_tdata = NULL;

        /*
         * Transfer response reference to serializer task so the
         * nominal path will not dec the response ref in this
         * pjproject callback thread.
         */
        if (ast_sip_push_task(client_state->serializer, handle_registration_response, response)) {
                ast_log(LOG_WARNING, "Failed to pass incoming registration response to threadpool\n");
                ao2_cleanup(response);
        }
}

/*! \brief Destructor function for registration state */
static void sip_outbound_registration_state_destroy(void *obj)
{
        struct sip_outbound_registration_state *state = obj;

        ast_debug(3, "Destroying registration state for registration to server '%s' from client '%s'\n",
                state->registration ? state->registration->server_uri : "",
                state->registration ? state->registration->client_uri : "");
        ao2_cleanup(state->registration);

        if (!state->client_state) {
                /* Nothing to do */
        } else if (!state->client_state->serializer) {
                ao2_ref(state->client_state, -1);
        } else if (ast_sip_push_task(state->client_state->serializer,
                handle_client_state_destruction, state->client_state)) {
                ast_log(LOG_WARNING, "Failed to pass outbound registration client destruction to threadpool\n");
                ao2_ref(state->client_state, -1);
        }
}

/*! \brief Destructor function for client registration state */
static void sip_outbound_registration_client_state_destroy(void *obj)
{
        struct sip_outbound_registration_client_state *client_state = obj;

        ast_statsd_log_string("PJSIP.registrations.count", AST_STATSD_GAUGE, "-1", 1.0);
        ast_statsd_log_string_va("PJSIP.registrations.state.%s", AST_STATSD_GAUGE, "-1", 1.0,
                sip_outbound_registration_status_str(client_state->status));

        ast_taskprocessor_unreference(client_state->serializer);
        ast_free(client_state->transport_name);
        ast_free(client_state->registration_name);
        if (client_state->last_tdata) {
                pjsip_tx_data_dec_ref(client_state->last_tdata);
        }
}

/*! \brief Allocator function for registration state */
static struct sip_outbound_registration_state *sip_outbound_registration_state_alloc(struct sip_outbound_registration *registration)
{
        struct sip_outbound_registration_state *state;
        char tps_name[AST_TASKPROCESSOR_MAX_NAME + 1];

        state = ao2_alloc(sizeof(*state), sip_outbound_registration_state_destroy);
        if (!state) {
                return NULL;
        }
        state->client_state = ao2_alloc(sizeof(*state->client_state),
                sip_outbound_registration_client_state_destroy);
        if (!state->client_state) {
                ao2_cleanup(state);
                return NULL;
        }

        state->client_state->status = SIP_REGISTRATION_UNREGISTERED;
        pj_timer_entry_init(&state->client_state->timer, 0, state->client_state,
                sip_outbound_registration_timer_cb);
        state->client_state->transport_name = ast_strdup(registration->transport);
        state->client_state->registration_name =
                ast_strdup(ast_sorcery_object_get_id(registration));

        ast_statsd_log_string("PJSIP.registrations.count", AST_STATSD_GAUGE, "+1", 1.0);
        ast_statsd_log_string_va("PJSIP.registrations.state.%s", AST_STATSD_GAUGE, "+1", 1.0,
                sip_outbound_registration_status_str(state->client_state->status));

        if (!state->client_state->transport_name
                || !state->client_state->registration_name) {
                ao2_cleanup(state);
                return NULL;
        }

        /* Create name with seq number appended. */
        ast_taskprocessor_build_name(tps_name, sizeof(tps_name), "pjsip/outreg/%s",
                ast_sorcery_object_get_id(registration));

        state->client_state->serializer = ast_sip_create_serializer_group(tps_name,
                shutdown_group);
        if (!state->client_state->serializer) {
                ao2_cleanup(state);
                return NULL;
        }

        state->registration = ao2_bump(registration);
        return state;
}

/*! \brief Destructor function for registration information */
static void sip_outbound_registration_destroy(void *obj)
{
        struct sip_outbound_registration *registration = obj;

        ast_sip_auth_vector_destroy(&registration->outbound_auths);
        ast_sip_security_mechanisms_vector_destroy(&registration->security_mechanisms);

        ast_string_field_free_memory(registration);
}

/*! \brief Allocator function for registration information */
static void *sip_outbound_registration_alloc(const char *name)
{
        struct sip_outbound_registration *registration;

        registration = ast_sorcery_generic_alloc(sizeof(*registration),
                sip_outbound_registration_destroy);
        if (!registration || ast_string_field_init(registration, 256)) {
                ao2_cleanup(registration);
                return NULL;
        }

        return registration;
}

/*! \brief Helper function which populates a pj_str_t with a contact header */
static int sip_dialog_create_contact(pj_pool_t *pool, pj_str_t *contact, const char *user,
        const pj_str_t *target, pjsip_tpselector *selector, const char *line, const char *header_params)
{
        pj_str_t tmp, local_addr;
        pjsip_uri *uri;
        pjsip_sip_uri *sip_uri;
        pjsip_transport_type_e type;
        int local_port;

        pj_strdup_with_null(pool, &tmp, target);

        if (!(uri = pjsip_parse_uri(pool, tmp.ptr, tmp.slen, 0)) ||
            (!PJSIP_URI_SCHEME_IS_SIP(uri) && !PJSIP_URI_SCHEME_IS_SIPS(uri))) {
                return -1;
        }

        sip_uri = pjsip_uri_get_uri(uri);

        type = pjsip_transport_get_type_from_name(&sip_uri->transport_param);
        if (PJSIP_URI_SCHEME_IS_SIPS(sip_uri)) {
                if (type == PJSIP_TRANSPORT_UNSPECIFIED
                        || !(pjsip_transport_get_flag_from_type(type) & PJSIP_TRANSPORT_SECURE)) {
                        type = PJSIP_TRANSPORT_TLS;
                }
        } else if (!sip_uri->transport_param.slen) {
                type = PJSIP_TRANSPORT_UDP;
        } else if (type == PJSIP_TRANSPORT_UNSPECIFIED) {
                return -1;
        }

        if (pj_strchr(&sip_uri->host, ':')) {
                type |= PJSIP_TRANSPORT_IPV6;
        }

        if (pjsip_tpmgr_find_local_addr(pjsip_endpt_get_tpmgr(ast_sip_get_pjsip_endpoint()),
                pool, type, selector, &local_addr, &local_port) != PJ_SUCCESS) {
                return -1;
        }

        if (!pj_strchr(&sip_uri->host, ':') && pj_strchr(&local_addr, ':')) {
                type |= PJSIP_TRANSPORT_IPV6;
        }

        contact->ptr = pj_pool_alloc(pool, PJSIP_MAX_URL_SIZE);
        contact->slen = pj_ansi_snprintf(contact->ptr, PJSIP_MAX_URL_SIZE,
                "<%s:%s@%s%.*s%s:%d%s%s%s%s>%s%s",
                ((pjsip_transport_get_flag_from_type(type) & PJSIP_TRANSPORT_SECURE) && PJSIP_URI_SCHEME_IS_SIPS(uri)) ? "sips" : "sip",
                user,
                (type & PJSIP_TRANSPORT_IPV6) ? "[" : "",
                (int)local_addr.slen,
                local_addr.ptr,
                (type & PJSIP_TRANSPORT_IPV6) ? "]" : "",
                local_port,
                (type != PJSIP_TRANSPORT_UDP && type != PJSIP_TRANSPORT_UDP6) ? ";transport=" : "",
                (type != PJSIP_TRANSPORT_UDP && type != PJSIP_TRANSPORT_UDP6) ? pjsip_transport_get_type_name(type) : "",
                !ast_strlen_zero(line) ? ";line=" : "",
                S_OR(line, ""),
                !ast_strlen_zero(header_params) ? ";" : "",
                S_OR(header_params, ""));

        return 0;
}

/*!
 * \internal
 * \brief Check if a registration can be reused
 *
 * This checks if the existing outbound registration's configuration differs from a newly-applied
 * outbound registration to see if the applied one.
 *
 * \param existing The pre-existing outbound registration
 * \param applied The newly-created registration
 */
static int can_reuse_registration(struct sip_outbound_registration *existing,
        struct sip_outbound_registration *applied)
{
        int rc = 1;
        struct ast_sorcery *sorcery = ast_sip_get_sorcery();
        struct ast_variable *ve = ast_sorcery_objectset_create(sorcery, existing);
        struct ast_variable *va = ast_sorcery_objectset_create(sorcery, applied);
        struct ast_variable *vc = NULL;

        if (ast_sorcery_changeset_create(ve, va, &vc) || vc != NULL) {
                rc = 0;
                ast_debug(4, "Registration '%s' changed.  Can't re-use.\n", ast_sorcery_object_get_id(existing));
        } else {
                ast_debug(4, "Registration '%s' didn't change.  Can re-use\n", ast_sorcery_object_get_id(existing));
        }

        ast_variables_destroy(ve);
        ast_variables_destroy(va);
        ast_variables_destroy(vc);

        return rc;
}

/*! \brief Get google oauth2 access token using refresh token */
static const char *fetch_google_access_token(const struct ast_sip_auth *auth)
{
        char *cmd = NULL;
        const char *token;
        const char *url = "https://www.googleapis.com/oauth2/v3/token";
        char buf[4096];
        int res;
        struct ast_json_error error;
        struct ast_json *json;

        /* set timeout to be shorter than default 180s (also checks func_curl is available) */
        if (ast_func_write(NULL, "CURLOPT(conntimeout)", "10")) {
                ast_log(LOG_ERROR, "CURL is unavailable. This is required for Google OAuth 2.0 authentication. Please ensure it is loaded.\n");
                return NULL;
        }

        res = ast_asprintf(&cmd,
                "CURL(%s,client_id=%s&client_secret=%s&refresh_token=%s&grant_type=refresh_token)",
                url, auth->oauth_clientid, auth->oauth_secret, auth->refresh_token);
        if (res < 0) {
                return NULL;
        }

        ast_debug(2, "Performing Google OAuth 2.0 authentication using command: %s\n", cmd);

        buf[0] = '\0';
        res = ast_func_read(NULL, cmd, buf, sizeof(buf));
        ast_free(cmd);
        if (res) {
                ast_log(LOG_ERROR, "Could not retrieve Google OAuth 2.0 authentication\n");
                return NULL;
        }

        ast_debug(2, "Google OAuth 2.0 authentication returned: %s\n", buf);

        json = ast_json_load_string(buf, &error);
        if (!json) {
                ast_log(LOG_ERROR, "Could not parse Google OAuth 2.0 authentication: %d(%d) %s: '%s'\n",
                        error.line, error.column, error.text, buf);
                return NULL;
        }

        token = ast_json_string_get(ast_json_object_get(json, "access_token"));
        if (!token) {
                ast_log(LOG_ERROR, "Could not find Google OAuth 2.0 access_token in: '%s'\n",
                        buf);
        }
        token = ast_strdup(token);
        ast_json_unref(json);
        return token;
}

/*!
 * \internal
 * \brief Set pjsip registration context with any authentication credentials that need to be
 * sent in the initial registration request
 *
 * \param regc The pjsip registration context
 * \param auth_vector The vector of configured authentication credentials
 */
static int set_outbound_initial_authentication_credentials(pjsip_regc *regc,
                const struct ast_sip_auth_vector *auth_vector)
{
        size_t auth_size = AST_VECTOR_SIZE(auth_vector);
        struct ast_sip_auth *auths[auth_size];
        const char *access_token;
        pjsip_cred_info auth_creds[1];
        pjsip_auth_clt_pref prefs;
        int res = 0;
        int idx;

        memset(auths, 0, sizeof(auths));
        if (ast_sip_retrieve_auths(auth_vector, auths)) {
                res = -1;
                goto cleanup;
        }

        for (idx = 0; idx < auth_size; ++idx) {
                switch (auths[idx]->type) {
                case AST_SIP_AUTH_TYPE_GOOGLE_OAUTH:
                        pj_cstr(&auth_creds[0].username, auths[idx]->auth_user);
                        pj_cstr(&auth_creds[0].scheme, "Bearer");
                        pj_cstr(&auth_creds[0].realm, auths[idx]->realm);
                        ast_debug(2, "Obtaining Google OAuth access token\n");
                        access_token = fetch_google_access_token(auths[idx]);
                        if (!access_token) {
                                ast_log(LOG_WARNING, "Obtaining Google OAuth access token failed\n");
                                access_token = auths[idx]->auth_pass;
                                res = -1;
                        }
                        ast_debug(2, "Setting data to '%s'\n", access_token);

                        pj_cstr(&auth_creds[0].data, access_token);
                        auth_creds[0].data_type = PJSIP_CRED_DATA_PLAIN_PASSWD;

                        pjsip_regc_set_credentials(regc, 1, auth_creds);

                        /* for oauth, send auth without waiting for unauthorized response */
                        prefs.initial_auth = PJ_TRUE;
                        pj_cstr(&prefs.algorithm, "oauth");
                        pjsip_regc_set_prefs(regc, &prefs);

                        if (access_token != auths[idx]->auth_pass) {
                                ast_free((char *) access_token);
                        }
                        break;
                default:
                        /* other cases handled after receiving auth rejection */
                        break;
                }
        }

cleanup:
        ast_sip_cleanup_auths(auths, auth_size);
        return res;
}

/*! \brief Helper function that allocates a pjsip registration client and configures it */
static int sip_outbound_registration_regc_alloc(void *data)
{
        struct sip_outbound_registration_state *state = data;
        RAII_VAR(struct sip_outbound_registration *, registration,
                 ao2_bump(state->registration), ao2_cleanup);
        pj_pool_t *pool;
        pj_str_t tmp;
        pjsip_uri *uri;
        pj_str_t server_uri, client_uri, contact_uri;
        pjsip_tpselector selector = { .type = PJSIP_TPSELECTOR_NONE, };

        pool = pjsip_endpt_create_pool(ast_sip_get_pjsip_endpoint(), "URI Validation", 256, 256);
        if (!pool) {
                ast_log(LOG_ERROR, "Could not create pool for URI validation on outbound registration '%s'\n",
                        ast_sorcery_object_get_id(registration));
                return -1;
        }

        pj_strdup2_with_null(pool, &tmp, registration->server_uri);
        uri = pjsip_parse_uri(pool, tmp.ptr, tmp.slen, 0);
        if (!uri) {
                ast_log(LOG_ERROR, "Invalid server URI '%s' specified on outbound registration '%s'\n",
                        registration->server_uri, ast_sorcery_object_get_id(registration));
                pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), pool);
                return -1;
        }

        pj_strdup2_with_null(pool, &tmp, registration->client_uri);
        uri = pjsip_parse_uri(pool, tmp.ptr, tmp.slen, 0);
        if (!uri) {
                ast_log(LOG_ERROR, "Invalid client URI '%s' specified on outbound registration '%s'\n",
                        registration->client_uri, ast_sorcery_object_get_id(registration));
                pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), pool);
                return -1;
        }

        pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), pool);

        ast_assert(state->client_state->client == NULL);
        if (pjsip_regc_create(ast_sip_get_pjsip_endpoint(), state->client_state,
                        sip_outbound_registration_response_cb,
                        &state->client_state->client) != PJ_SUCCESS) {
                return -1;
        }

        ast_sip_set_tpselector_from_transport_name(registration->transport, &selector);
        pjsip_regc_set_transport(state->client_state->client, &selector);

        if (!ast_strlen_zero(registration->outbound_proxy)) {
                pjsip_route_hdr route_set, *route;
                static const pj_str_t ROUTE_HNAME = { "Route", 5 };
                pj_str_t tmp;

                pj_list_init(&route_set);

                pj_strdup2_with_null(pjsip_regc_get_pool(state->client_state->client), &tmp,
                        registration->outbound_proxy);
                route = pjsip_parse_hdr(pjsip_regc_get_pool(state->client_state->client),
                        &ROUTE_HNAME, tmp.ptr, tmp.slen, NULL);
                if (!route) {
                        ast_sip_tpselector_unref(&selector);
                        return -1;
                }
                pj_list_insert_nodes_before(&route_set, route);

                pjsip_regc_set_route_set(state->client_state->client, &route_set);
        }

        if (state->registration->line) {
                ast_generate_random_string(state->client_state->line, sizeof(state->client_state->line));
        }

        pj_cstr(&server_uri, registration->server_uri);

        if (sip_dialog_create_contact(pjsip_regc_get_pool(state->client_state->client),
                &contact_uri, S_OR(registration->contact_user, "s"), &server_uri, &selector,
                state->client_state->line, registration->contact_header_params)) {
                ast_sip_tpselector_unref(&selector);
                return -1;
        }

        ast_sip_tpselector_unref(&selector);

        pj_cstr(&client_uri, registration->client_uri);
        if (pjsip_regc_init(state->client_state->client, &server_uri, &client_uri,
                &client_uri, 1, &contact_uri, registration->expiration) != PJ_SUCCESS) {
                return -1;
        }

        return 0;
}

/*! \brief Helper function which performs a single registration */
static int sip_outbound_registration_perform(void *data)
{
        struct sip_outbound_registration_state *state = data;
        struct sip_outbound_registration *registration = ao2_bump(state->registration);
        size_t i;
        int max_delay;

        /* Just in case the client state is being reused for this registration, free the auth information */
        ast_sip_auth_vector_destroy(&state->client_state->outbound_auths);
        ast_sip_security_mechanisms_vector_destroy(&state->client_state->security_mechanisms);
        ast_sip_security_mechanisms_vector_destroy(&state->client_state->server_security_mechanisms);

        AST_VECTOR_INIT(&state->client_state->outbound_auths, AST_VECTOR_SIZE(&registration->outbound_auths));
        for (i = 0; i < AST_VECTOR_SIZE(&registration->outbound_auths); ++i) {
                char *name = ast_strdup(AST_VECTOR_GET(&registration->outbound_auths, i));

                if (name && AST_VECTOR_APPEND(&state->client_state->outbound_auths, name)) {
                        ast_free(name);
                }
        }
        ast_sip_security_mechanisms_vector_copy(&state->client_state->security_mechanisms,
                                                                                        &registration->security_mechanisms);
        state->client_state->retry_interval = registration->retry_interval;
        state->client_state->forbidden_retry_interval = registration->forbidden_retry_interval;
        state->client_state->fatal_retry_interval = registration->fatal_retry_interval;
        state->client_state->max_retries = registration->max_retries;
        state->client_state->retries = 0;
        state->client_state->support_path = registration->support_path;
        state->client_state->support_outbound = registration->support_outbound;
        state->client_state->security_negotiation = registration->security_negotiation;
        state->client_state->auth_rejection_permanent = registration->auth_rejection_permanent;
        max_delay = registration->max_random_initial_delay;

        pjsip_regc_update_expires(state->client_state->client, registration->expiration);

        /* n mod 0 is undefined, so don't let that happen */
        schedule_registration(state->client_state, (max_delay ? ast_random() % max_delay : 0) + 1);

        ao2_ref(registration, -1);
        ao2_ref(state, -1);
        return 0;
}

/*! \brief Apply function which finds or allocates a state structure */
static int sip_outbound_registration_apply(const struct ast_sorcery *sorcery, void *obj)
{
        RAII_VAR(struct ao2_container *, states, ao2_global_obj_ref(current_states), ao2_cleanup);
        RAII_VAR(struct sip_outbound_registration_state *, state, NULL, ao2_cleanup);
        RAII_VAR(struct sip_outbound_registration_state *, new_state, NULL, ao2_cleanup);
        struct sip_outbound_registration *applied = obj;

        if (!states) {
                /* Global container has gone.  Likely shutting down. */
                return -1;
        }
        state = ao2_find(states, ast_sorcery_object_get_id(applied), OBJ_SEARCH_KEY);

        ast_debug(4, "Applying configuration to outbound registration '%s'\n", ast_sorcery_object_get_id(applied));

        if (ast_strlen_zero(applied->server_uri)) {
                ast_log(LOG_ERROR, "No server URI specified on outbound registration '%s'\n",
                        ast_sorcery_object_get_id(applied));
                return -1;
        } else if (ast_sip_validate_uri_length(applied->server_uri)) {
                        ast_log(LOG_ERROR, "Server URI or hostname length exceeds pjproject limit or is not a sip(s) uri: '%s'\n",
                                ast_sorcery_object_get_id(applied));
                        return -1;
        } else if (ast_strlen_zero(applied->client_uri)) {
                ast_log(LOG_ERROR, "No client URI specified on outbound registration '%s'\n",
                        ast_sorcery_object_get_id(applied));
                return -1;
        } else if (ast_sip_validate_uri_length(applied->client_uri)) {
                        ast_log(LOG_ERROR, "Client URI or hostname length exceeds pjproject limit or is not a sip(s) uri: '%s'\n",
                                ast_sorcery_object_get_id(applied));
                        return -1;
        } else if (applied->line && ast_strlen_zero(applied->endpoint)) {
                ast_log(LOG_ERROR, "Line support has been enabled on outbound registration '%s' without providing an endpoint\n",
                        ast_sorcery_object_get_id(applied));
                return -1;
        } else if (!ast_strlen_zero(applied->endpoint) && !applied->line) {
                ast_log(LOG_ERROR, "An endpoint has been specified on outbound registration '%s' without enabling line support\n",
                        ast_sorcery_object_get_id(applied));
                return -1;
        }

        if (state && can_reuse_registration(state->registration, applied)) {
                ast_debug(4,
                        "No change between old configuration and new configuration on outbound registration '%s'. Using previous state\n",
                        ast_sorcery_object_get_id(applied));

                /*
                 * This is OK to replace without relinking the state in the
                 * current_states container since state->registration and
                 * applied have the same key.
                 */
                ao2_lock(states);
                ao2_replace(state->registration, applied);
                ao2_unlock(states);
                return 0;
        }

        if (!(new_state = sip_outbound_registration_state_alloc(applied))) {
                return -1;
        }

        if (ast_sip_push_task_wait_serializer(new_state->client_state->serializer,
                sip_outbound_registration_regc_alloc, new_state)) {
                return -1;
        }

        if (ast_sip_push_task(new_state->client_state->serializer,
                              sip_outbound_registration_perform, ao2_bump(new_state))) {
                ast_log(LOG_ERROR, "Failed to perform outbound registration on '%s'\n",
                        ast_sorcery_object_get_id(new_state->registration));
                ao2_ref(new_state, -1);
                return -1;
        }

        ao2_lock(states);
        if (state) {
                ao2_unlink(states, state);
        }
        ao2_link(states, new_state);
        ao2_unlock(states);

        return 0;
}

static int security_mechanism_to_str(const void *obj, const intptr_t *args, char **buf)
{
        const struct sip_outbound_registration *registration = obj;

        return ast_sip_security_mechanisms_to_str(&registration->security_mechanisms, 0, buf);
}

static const char *security_negotiation_map[] = {
        [AST_SIP_SECURITY_NEG_NONE] = "no",
        [AST_SIP_SECURITY_NEG_MEDIASEC] = "mediasec",
};

static int security_negotiation_to_str(const void *obj, const intptr_t *args, char **buf)
{
        const struct sip_outbound_registration *registration = obj;
        if (ARRAY_IN_BOUNDS(registration->security_negotiation, security_negotiation_map)) {
                *buf = ast_strdup(security_negotiation_map[registration->security_negotiation]);
        }
        return 0;
}

static int security_mechanisms_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
{
        struct sip_outbound_registration *registration = obj;

        return ast_sip_security_mechanism_vector_init(&registration->security_mechanisms, var->value);
}

static int security_negotiation_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
{
        struct sip_outbound_registration *registration = obj;

        return ast_sip_set_security_negotiation(&registration->security_negotiation, var->value);
}

static int outbound_auth_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
{
        struct sip_outbound_registration *registration = obj;

        return ast_sip_auth_vector_init(&registration->outbound_auths, var->value);
}

static int outbound_auths_to_str(const void *obj, const intptr_t *args, char **buf)
{
        const struct sip_outbound_registration *registration = obj;

        return ast_sip_auths_to_str(&registration->outbound_auths, buf);
}

static int outbound_auths_to_var_list(const void *obj, struct ast_variable **fields)
{
        const struct sip_outbound_registration *registration = obj;
        int i;
        struct ast_variable *head = NULL;

        for (i = 0; i < AST_VECTOR_SIZE(&registration->outbound_auths) ; i++) {
                ast_variable_list_append(&head, ast_variable_new("outbound_auth",
                        AST_VECTOR_GET(&registration->outbound_auths, i), ""));
        }

        if (head) {
                *fields = head;
        }

        return 0;
}

static int unregister_task(void *obj)
{
        struct sip_outbound_registration_state *state = obj;
        struct pjsip_regc *client = state->client_state->client;
        pjsip_tx_data *tdata;
        pjsip_regc_info info;

        pjsip_regc_get_info(client, &info);
        ast_debug(1, "Unregistering contacts with server '%s' from client '%s'\n",
                state->registration->server_uri, state->registration->client_uri);

        cancel_registration(state->client_state);

        if (pjsip_regc_unregister(client, &tdata) == PJ_SUCCESS
                && add_configured_supported_headers(state->client_state, tdata)) {
                registration_client_send(state->client_state, tdata);
        }

        ao2_ref(state, -1);
        return 0;
}

static int queue_unregister(struct sip_outbound_registration_state *state)
{
        ao2_ref(state, +1);
        if (ast_sip_push_task(state->client_state->serializer, unregister_task, state)) {
                ao2_ref(state, -1);
                return -1;
        }

        return 0;
}

static int queue_register(struct sip_outbound_registration_state *state)
{
        ao2_ref(state, +1);
        if (ast_sip_push_task(state->client_state->serializer, sip_outbound_registration_perform, state)) {
                ao2_ref(state, -1);
                return -1;
        }

        return 0;
}

static void unregister_all(void)
{
        struct ao2_container *states;

        states = ao2_global_obj_ref(current_states);
        if (!states) {
                return;
        }

        /* Clean out all the states and let sorcery handle recreating the registrations */
        ao2_callback(states, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, NULL, NULL);
        ao2_ref(states, -1);
}

static void reregister_all(void)
{
        unregister_all();
        ast_sorcery_load_object(ast_sip_get_sorcery(), "registration");
}

static char *cli_complete_registration(const char *line, const char *word,
                                       int pos, int state)
{
        char *result = NULL;
        int wordlen;
        int which = 0;
        struct sip_outbound_registration *registration;
        struct ao2_container *registrations;
        struct ao2_iterator i;

        if (pos != 3) {
                return NULL;
        }

        wordlen = strlen(word);
        if (wordlen == 0 && ++which > state) {
                return ast_strdup("*all");
        }

        registrations = ast_sorcery_retrieve_by_fields(ast_sip_get_sorcery(), "registration",
                AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
        if (!registrations) {
                return NULL;
        }

        i = ao2_iterator_init(registrations, 0);
        while ((registration = ao2_iterator_next(&i))) {
                const char *name = ast_sorcery_object_get_id(registration);

                if (!strncasecmp(word, name, wordlen) && ++which > state) {
                        result = ast_strdup(name);
                }

                ao2_ref(registration, -1);
                if (result) {
                        break;
                }
        }
        ao2_iterator_destroy(&i);

        ao2_ref(registrations, -1);
        return result;
}

static char *cli_unregister(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
        struct sip_outbound_registration_state *state;
        const char *registration_name;

        switch (cmd) {
        case CLI_INIT:
                e->command = "pjsip send unregister";
                e->usage =
                        "Usage: pjsip send unregister <registration> | *all\n"
                        "       Unregisters the specified (or all) outbound registration(s) "
                        "and stops future registration attempts.\n";
                return NULL;
        case CLI_GENERATE:
                return cli_complete_registration(a->line, a->word, a->pos, a->n);
        }

        if (a->argc != 4) {
                return CLI_SHOWUSAGE;
        }

        registration_name = a->argv[3];

        if (strcmp(registration_name, "*all") == 0) {
                unregister_all();
                ast_cli(a->fd, "Unregister all queued\n");
                return CLI_SUCCESS;
        }

        state = get_state(registration_name);
        if (!state) {
                ast_cli(a->fd, "Unable to retrieve registration %s\n", registration_name);
                return CLI_FAILURE;
        }

        if (queue_unregister(state)) {
                ast_cli(a->fd, "Failed to queue unregistration\n");
        }

        ao2_ref(state, -1);
        return CLI_SUCCESS;
}

static char *cli_register(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
        struct sip_outbound_registration_state *state;
        const char *registration_name;

        switch (cmd) {
        case CLI_INIT:
                e->command = "pjsip send register";
                e->usage =
                        "Usage: pjsip send register <registration> | *all \n"
                        "       Unregisters the specified (or all) outbound "
                        "registration(s) then starts registration(s) and schedules re-registrations.\n";
                return NULL;
        case CLI_GENERATE:
                return cli_complete_registration(a->line, a->word, a->pos, a->n);
        }

        if (a->argc != 4) {
                return CLI_SHOWUSAGE;
        }

        registration_name = a->argv[3];

        if (strcmp(registration_name, "*all") == 0) {
                reregister_all();
                ast_cli(a->fd, "Re-register all queued\n");
                return CLI_SUCCESS;
        }

        state = get_state(registration_name);
        if (!state) {
                ast_cli(a->fd, "Unable to retrieve registration %s\n", registration_name);
                return CLI_FAILURE;
        }

        /* We need to serialize the unregister and register so they need
         * to be queued as separate tasks.
         */
        if (queue_unregister(state)) {
                ast_cli(a->fd, "Failed to queue unregistration\n");
        } else if (queue_register(state)) {
                ast_cli(a->fd, "Failed to queue registration\n");
        }

        ao2_ref(state, -1);
        return CLI_SUCCESS;
}

static int ami_unregister(struct mansession *s, const struct message *m)
{
        const char *registration_name = astman_get_header(m, "Registration");
        struct sip_outbound_registration_state *state;

        if (ast_strlen_zero(registration_name)) {
                astman_send_error(s, m, "Registration parameter missing.");
                return 0;
        }

        if (strcmp(registration_name, "*all") == 0) {
                unregister_all();
                astman_send_ack(s, m, "Unregistrations queued.");
                return 0;
        }

        state = get_state(registration_name);
        if (!state) {
                astman_send_error(s, m, "Unable to retrieve registration entry\n");
                return 0;
        }

        if (queue_unregister(state)) {
                astman_send_ack(s, m, "Failed to queue unregistration");
        } else {
                astman_send_ack(s, m, "Unregistration sent");
        }

        ao2_ref(state, -1);
        return 0;
}

static int ami_register(struct mansession *s, const struct message *m)
{
        const char *registration_name = astman_get_header(m, "Registration");
        struct sip_outbound_registration_state *state;

        if (ast_strlen_zero(registration_name)) {
                astman_send_error(s, m, "Registration parameter missing.");
                return 0;
        }

        if (strcmp(registration_name, "*all") == 0) {
                reregister_all();
                astman_send_ack(s, m, "Reregistrations queued.");
                return 0;
        }

        state = get_state(registration_name);
        if (!state) {
                astman_send_error(s, m, "Unable to retrieve registration entry\n");
                return 0;
        }

        /* We need to serialize the unregister and register so they need
         * to be queued as separate tasks.
         */
        if (queue_unregister(state)) {
                astman_send_ack(s, m, "Failed to queue unregistration");
        } else if (queue_register(state)) {
                astman_send_ack(s, m, "Failed to queue unregistration");
        } else {
                astman_send_ack(s, m, "Reregistration sent");
        }

        ao2_ref(state, -1);
        return 0;
}

struct sip_ami_outbound {
        struct ast_sip_ami *ami;
        int registered;
        int not_registered;
        struct sip_outbound_registration *registration;
};

static int ami_outbound_registration_task(void *obj)
{
        struct sip_ami_outbound *ami = obj;
        struct ast_str *buf;
        struct sip_outbound_registration_state *state;

        buf = ast_sip_create_ami_event("OutboundRegistrationDetail", ami->ami);
        if (!buf) {
                return -1;
        }

        ast_sip_sorcery_object_to_ami(ami->registration, &buf);

        if ((state = get_state(ast_sorcery_object_get_id(ami->registration)))) {
                pjsip_regc_info info;

                if (state->client_state->status == SIP_REGISTRATION_REGISTERED) {
                        ++ami->registered;
                } else {
                        ++ami->not_registered;
                }

                ast_str_append(&buf, 0, "Status: %s\r\n",
                        sip_outbound_registration_status_str(state->client_state->status));

                pjsip_regc_get_info(state->client_state->client, &info);
                ast_str_append(&buf, 0, "NextReg: %d\r\n", info.next_reg);
                ao2_ref(state, -1);
        }

        astman_append(ami->ami->s, "%s\r\n", ast_str_buffer(buf));
        ast_free(buf);

        return ast_sip_format_auths_ami(&ami->registration->outbound_auths, ami->ami);
}

static int ami_outbound_registration_detail(void *obj, void *arg, int flags)
{
        struct sip_ami_outbound *ami = arg;

        ami->registration = obj;
        return ast_sip_push_task_wait_servant(NULL, ami_outbound_registration_task, ami);
}

static int ami_show_outbound_registrations(struct mansession *s,
                                           const struct message *m)
{
        struct ast_sip_ami ami = { .s = s, .m = m, .action_id = astman_get_header(m, "ActionID"), };
        struct sip_ami_outbound ami_outbound = { .ami = &ami };
        struct ao2_container *regs;

        regs = get_registrations();
        if (!regs) {
                astman_send_error(s, m, "Unable to retrieve "
                                  "outbound registrations\n");
                return -1;
        }

        astman_send_listack(s, m, "Following are Events for each Outbound registration",
                "start");

        ao2_callback(regs, OBJ_NODATA, ami_outbound_registration_detail, &ami_outbound);

        astman_send_list_complete_start(s, m, "OutboundRegistrationDetailComplete",
                ami_outbound.registered + ami_outbound.not_registered);
        astman_append(s,
                "Registered: %d\r\n"
                "NotRegistered: %d\r\n",
                ami_outbound.registered,
                ami_outbound.not_registered);
        astman_send_list_complete_end(s);

        ao2_ref(regs, -1);
        return 0;
}

static struct ao2_container *cli_get_container(const char *regex)
{
        RAII_VAR(struct ao2_container *, container, NULL, ao2_cleanup);
        struct ao2_container *s_container;

        container = ast_sorcery_retrieve_by_regex(ast_sip_get_sorcery(), "registration", regex);
        if (!container) {
                return NULL;
        }

        s_container = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_NOLOCK, 0,
                ast_sorcery_object_id_sort, ast_sorcery_object_id_compare);
        if (!s_container) {
                return NULL;
        }

        if (ao2_container_dup(s_container, container, 0)) {
                ao2_ref(s_container, -1);
                return NULL;
        }

        return s_container;
}

static int cli_iterator(void *container, ao2_callback_fn callback, void *args)
{
        ao2_callback(container, OBJ_NODATA, callback, args);

        return 0;
}

static void *cli_retrieve_by_id(const char *id)
{
        struct ao2_container *states;
        void *obj = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "registration", id);

        if (!obj) {
                /* if the object no longer exists then remove its state  */
                states = ao2_global_obj_ref(current_states);
                if (states) {
                        ao2_find(states, id, OBJ_SEARCH_KEY | OBJ_UNLINK | OBJ_NODATA);
                        ao2_ref(states, -1);
                }
        }

        return obj;
}

static int cli_print_header(void *obj, void *arg, int flags)
{
        struct ast_sip_cli_context *context = arg;

        ast_assert(context->output_buffer != NULL);

        ast_str_append(&context->output_buffer, 0,
                " <Registration/ServerURI..............................>  <Auth....................>  <Status.......>\n");

        return 0;
}

static int cli_print_body(void *obj, void *arg, int flags)
{
        struct sip_outbound_registration *registration = obj;
        struct ast_sip_cli_context *context = arg;
        const char *id = ast_sorcery_object_get_id(registration);
        struct sip_outbound_registration_state *state = get_state(id);
        int expsecs;
#define REGISTRATION_URI_FIELD_LEN      53

        ast_assert(context->output_buffer != NULL);
        expsecs = state ? state->client_state->registration_expires - ((int) time(NULL)) : 0;

        ast_str_append(&context->output_buffer, 0, " %-s/%-*.*s  %-26s  %-16s %s%d%s\n",
                id,
                (int) (REGISTRATION_URI_FIELD_LEN - strlen(id)),
                (int) (REGISTRATION_URI_FIELD_LEN - strlen(id)),
                registration->server_uri,
                AST_VECTOR_SIZE(&registration->outbound_auths)
                        ? AST_VECTOR_GET(&registration->outbound_auths, 0)
                        : "n/a",
                (state ? sip_outbound_registration_status_str(state->client_state->status) : "Unregistered"),
                state ? " (exp. " : "", abs(expsecs), state ? (expsecs < 0 ? "s ago)" : "s)") : "");
        ao2_cleanup(state);

        if (context->show_details
                || (context->show_details_only_level_0 && context->indent_level == 0)) {
                ast_str_append(&context->output_buffer, 0, "\n");
                ast_sip_cli_print_sorcery_objectset(registration, context, 0);
        }

        return 0;
}

/*
 * A function pointer to callback needs to be within the
 * module in order to avoid problems with an undefined
 * symbol when the module is loaded.
 */
static char *my_cli_traverse_objects(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
        return ast_sip_cli_traverse_objects(e, cmd, a);
}

static struct ast_cli_entry cli_outbound_registration[] = {
        AST_CLI_DEFINE(cli_unregister, "Unregisters outbound registration target"),
        AST_CLI_DEFINE(cli_register, "Registers an outbound registration target"),
        AST_CLI_DEFINE(my_cli_traverse_objects, "List PJSIP Registrations",
                .command = "pjsip list registrations",
                .usage = "Usage: pjsip list registrations [ like <pattern> ]\n"
                                "       List the configured PJSIP Registrations\n"
                                "       Optional regular expression pattern is used to filter the list.\n"),
        AST_CLI_DEFINE(my_cli_traverse_objects, "Show PJSIP Registrations",
                .command = "pjsip show registrations",
                .usage = "Usage: pjsip show registrations [ like <pattern> ]\n"
                                "       Show the configured PJSIP Registrations\n"
                                "       Optional regular expression pattern is used to filter the list.\n"),
        AST_CLI_DEFINE(my_cli_traverse_objects, "Show PJSIP Registration",
                .command = "pjsip show registration",
                .usage = "Usage: pjsip show registration <id>\n"
                                 "       Show the configured PJSIP Registration\n"),
};

static struct ast_sip_cli_formatter_entry *cli_formatter;

static void auth_observer(const char *type)
{
        struct sip_outbound_registration *registration;
        struct sip_outbound_registration_state *state;
        struct ao2_container *regs;
        const char *registration_id;
        struct ao2_iterator i;

        ast_debug(4, "Auths updated. Checking for any outbound registrations that are in permanent rejected state so they can be retried\n");

        regs = ast_sorcery_retrieve_by_fields(ast_sip_get_sorcery(), "registration",
                AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
        if (!regs || ao2_container_count(regs) == 0) {
                ao2_cleanup(regs);
                return;
        }

        i = ao2_iterator_init(regs, 0);
        for (; (registration = ao2_iterator_next(&i)); ao2_ref(registration, -1)) {
                registration_id = ast_sorcery_object_get_id(registration);
                state = get_state(registration_id);
                if (state && state->client_state->status == SIP_REGISTRATION_REJECTED_PERMANENT) {
                        ast_debug(4, "Trying outbound registration '%s' again\n", registration_id);

                        if (ast_sip_push_task(state->client_state->serializer,
                                              sip_outbound_registration_perform, ao2_bump(state))) {
                                ast_log(LOG_ERROR, "Failed to perform outbound registration on '%s'\n", registration_id);
                                ao2_ref(state, -1);
                        }
                }
                ao2_cleanup(state);
        }
        ao2_iterator_destroy(&i);
        ao2_cleanup(regs);
}

static const struct ast_sorcery_observer observer_callbacks_auth = {
        .loaded = auth_observer,
};

static int check_state(void *obj, void *arg, int flags)
{
        struct sip_outbound_registration_state *state = obj;
        struct sip_outbound_registration *registration;

        registration = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "registration",
                ast_sorcery_object_get_id(state->registration));
        if (!registration) {
                /* This is a dead registration */
                return CMP_MATCH;
        }

        ao2_ref(registration, -1);
        return 0;
}

/*!
 * \internal
 * \brief Observer to purge dead registration states.
 *
 * \param name Module name owning the sorcery instance.
 * \param sorcery Instance being observed.
 * \param object_type Name of object being observed.
 * \param reloaded Non-zero if the object is being reloaded.
 */
static void registration_loaded_observer(const char *name, const struct ast_sorcery *sorcery, const char *object_type, int reloaded)
{
        struct ao2_container *states;

        if (strcmp(object_type, "registration")) {
                /* Not interested */
                return;
        }

        states = ao2_global_obj_ref(current_states);
        if (!states) {
                /* Global container has gone.  Likely shutting down. */
                return;
        }

        /*
         * Refresh the current configured registrations. We don't need to hold
         * onto the objects, as the apply handler will cause their states to
         * be created appropriately.
         */
        ao2_cleanup(get_registrations());

        /* Now to purge dead registrations. */
        ao2_callback(states, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, check_state, NULL);
        ao2_ref(states, -1);
}

static const struct ast_sorcery_instance_observer observer_callbacks_registrations = {
        .object_type_loaded = registration_loaded_observer,
};

static void registration_deleted_observer(const void *obj)
{
        const struct sip_outbound_registration *registration = obj;
        struct ao2_container *states;

        states = ao2_global_obj_ref(current_states);
        if (!states) {
                /* Global container has gone.  Likely shutting down. */
                return;
        }

        ao2_find(states, ast_sorcery_object_get_id(registration), OBJ_UNLINK | OBJ_NODATA | OBJ_SEARCH_KEY);

        ao2_ref(states, -1);
}

static const struct ast_sorcery_observer registration_observer = {
        .deleted = registration_deleted_observer,
};

static void network_change_stasis_cb(void *data, struct stasis_subscription *sub, struct stasis_message *message)
{
        /* This callback is only concerned with network change messages from the system topic. */
        if (stasis_message_type(message) != ast_network_change_type()) {
                return;
        }
        ast_debug(3, "Received network change event\n");

        reregister_all();
}

static int unload_module(void)
{
        int remaining;

        network_change_sub = stasis_unsubscribe_and_join(network_change_sub);

        ast_manager_unregister("PJSIPShowRegistrationsOutbound");
        ast_manager_unregister("PJSIPUnregister");
        ast_manager_unregister("PJSIPRegister");

        ast_cli_unregister_multiple(cli_outbound_registration, ARRAY_LEN(cli_outbound_registration));
        ast_sip_unregister_cli_formatter(cli_formatter);
        cli_formatter = NULL;

        ast_sip_unregister_endpoint_identifier(&line_identifier);

        ast_sorcery_observer_remove(ast_sip_get_sorcery(), "auth", &observer_callbacks_auth);
        ast_sorcery_instance_observer_remove(ast_sip_get_sorcery(), &observer_callbacks_registrations);

        ast_sorcery_object_unregister(ast_sip_get_sorcery(), "registration");

        ao2_global_obj_release(current_states);

        ast_sip_transport_monitor_unregister_all(registration_transport_shutdown_cb, NULL, NULL);

        /* Wait for registration serializers to get destroyed. */
        ast_debug(2, "Waiting for registration transactions to complete for unload.\n");
        remaining = ast_serializer_shutdown_group_join(shutdown_group, MAX_UNLOAD_TIMEOUT_TIME);
        if (remaining) {
                /*
                 * NOTE: We probably have a sip_outbound_registration_client_state
                 * ref leak if the remaining count cannot reach zero after a few
                 * minutes of trying to unload.
                 */
                ast_log(LOG_WARNING, "Unload incomplete.  Could not stop %d outbound registrations.  Try again later.\n",
                        remaining);
                return -1;
        }

        ast_debug(2, "Successful shutdown.\n");

        ao2_cleanup(shutdown_group);
        shutdown_group = NULL;

        return 0;
}

static int load_module(void)
{
        struct ao2_container *new_states;

        shutdown_group = ast_serializer_shutdown_group_alloc();
        if (!shutdown_group) {
                return AST_MODULE_LOAD_DECLINE;
        }

        /* Create outbound registration states container. */
        new_states = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
                DEFAULT_STATE_BUCKETS, registration_state_hash, NULL, registration_state_cmp);
        if (!new_states) {
                ast_log(LOG_ERROR, "Unable to allocate registration states container\n");
                unload_module();
                return AST_MODULE_LOAD_DECLINE;
        }
        ao2_global_obj_replace_unref(current_states, new_states);
        ao2_ref(new_states, -1);

        /*
         * Register sorcery object descriptions.
         */
        ast_sorcery_apply_config(ast_sip_get_sorcery(), "res_pjsip_outbound_registration");
        ast_sorcery_apply_default(ast_sip_get_sorcery(), "registration", "config", "pjsip.conf,criteria=type=registration");

        if (ast_sorcery_object_register(ast_sip_get_sorcery(), "registration", sip_outbound_registration_alloc, NULL, sip_outbound_registration_apply)) {
                unload_module();
                return AST_MODULE_LOAD_DECLINE;
        }

        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "type", "", OPT_NOOP_T, 0, 0);
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "server_uri", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, server_uri));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "client_uri", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, client_uri));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "contact_user", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, contact_user));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "contact_header_params", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, contact_header_params));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "transport", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, transport));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "outbound_proxy", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, outbound_proxy));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "expiration", "3600", OPT_UINT_T, 0, FLDSET(struct sip_outbound_registration, expiration));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "max_random_initial_delay", "10", OPT_UINT_T, 0, FLDSET(struct sip_outbound_registration, max_random_initial_delay));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "retry_interval", "60", OPT_UINT_T, 0, FLDSET(struct sip_outbound_registration, retry_interval));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "forbidden_retry_interval", "0", OPT_UINT_T, 0, FLDSET(struct sip_outbound_registration, forbidden_retry_interval));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "fatal_retry_interval", "0", OPT_UINT_T, 0, FLDSET(struct sip_outbound_registration, fatal_retry_interval));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "max_retries", "10", OPT_UINT_T, 0, FLDSET(struct sip_outbound_registration, max_retries));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "auth_rejection_permanent", "yes", OPT_BOOL_T, 1, FLDSET(struct sip_outbound_registration, auth_rejection_permanent));
        ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), "registration", "outbound_auth", "", outbound_auth_handler, outbound_auths_to_str, outbound_auths_to_var_list, 0, 0);
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "support_path", "no", OPT_BOOL_T, 1, FLDSET(struct sip_outbound_registration, support_path));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "support_outbound", "no", OPT_YESNO_T, 1, FLDSET(struct sip_outbound_registration, support_outbound));
        ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), "registration", "security_negotiation", "no", security_negotiation_handler, security_negotiation_to_str, NULL, 0, 0);
        ast_sorcery_object_field_register_custom(ast_sip_get_sorcery(), "registration", "security_mechanisms", "", security_mechanisms_handler, security_mechanism_to_str, NULL, 0, 0);
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "line", "no", OPT_BOOL_T, 1, FLDSET(struct sip_outbound_registration, line));
        ast_sorcery_object_field_register(ast_sip_get_sorcery(), "registration", "endpoint", "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct sip_outbound_registration, endpoint));

        /*
         * Register sorcery observers.
         */
        if (ast_sorcery_instance_observer_add(ast_sip_get_sorcery(),
                &observer_callbacks_registrations)
                || ast_sorcery_observer_add(ast_sip_get_sorcery(), "auth",
                        &observer_callbacks_auth)
                || ast_sorcery_observer_add(ast_sip_get_sorcery(), "registration",
                        &registration_observer)) {
                ast_log(LOG_ERROR, "Unable to register observers.\n");
                unload_module();
                return AST_MODULE_LOAD_DECLINE;
        }

        /* Register how this module identifies endpoints. */
        ast_sip_register_endpoint_identifier(&line_identifier);

        /* Register CLI commands. */
        cli_formatter = ao2_alloc(sizeof(struct ast_sip_cli_formatter_entry), NULL);
        if (!cli_formatter) {
                ast_log(LOG_ERROR, "Unable to allocate memory for cli formatter\n");
                unload_module();
                return AST_MODULE_LOAD_DECLINE;
        }
        cli_formatter->name = "registration";
        cli_formatter->print_header = cli_print_header;
        cli_formatter->print_body = cli_print_body;
        cli_formatter->get_container = cli_get_container;
        cli_formatter->iterate = cli_iterator;
        cli_formatter->get_id = ast_sorcery_object_get_id;
        cli_formatter->retrieve_by_id = cli_retrieve_by_id;
        ast_sip_register_cli_formatter(cli_formatter);
        ast_cli_register_multiple(cli_outbound_registration, ARRAY_LEN(cli_outbound_registration));

        /* Register AMI actions. */
        ast_manager_register_xml("PJSIPUnregister", EVENT_FLAG_SYSTEM | EVENT_FLAG_REPORTING, ami_unregister);
        ast_manager_register_xml("PJSIPRegister", EVENT_FLAG_SYSTEM | EVENT_FLAG_REPORTING, ami_register);
        ast_manager_register_xml("PJSIPShowRegistrationsOutbound", EVENT_FLAG_SYSTEM | EVENT_FLAG_REPORTING, ami_show_outbound_registrations);

        /* Clear any previous statsd gauges in case we weren't shutdown cleanly */
        ast_statsd_log("PJSIP.registrations.count", AST_STATSD_GAUGE, 0);
        ast_statsd_log("PJSIP.registrations.state.Registered", AST_STATSD_GAUGE, 0);
        ast_statsd_log("PJSIP.registrations.state.Unregistered", AST_STATSD_GAUGE, 0);
        ast_statsd_log("PJSIP.registrations.state.Rejected", AST_STATSD_GAUGE, 0);

        /* Load configuration objects */
        ast_sorcery_load_object(ast_sip_get_sorcery(), "registration");

        network_change_sub = stasis_subscribe(ast_system_topic(),
                network_change_stasis_cb, NULL);
        stasis_subscription_accept_message_type(network_change_sub, ast_network_change_type());
        stasis_subscription_set_filter(network_change_sub, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);

        return AST_MODULE_LOAD_SUCCESS;
}

static int reload_module(void)
{
        ast_sorcery_reload_object(ast_sip_get_sorcery(), "registration");
        return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Outbound Registration Support",
        .support_level = AST_MODULE_SUPPORT_CORE,
        .load = load_module,
        .reload = reload_module,
        .unload = unload_module,
        .load_pri = AST_MODPRI_APP_DEPEND,
        .requires = "res_pjsip",
        .optional_modules = "res_statsd",
);