# Basic buddy status notification
[Tutorials:]

This program is a _very_ simple usage example of liblinphone, demonstrating how to initiate SIP subscriptions and receive notifications from a sip uri identity passed from the command line.
Argument must be like sip:jehan@sip.linphone.org .
ex budy_list sip:jehan@sip.linphone.org
Subscription is cleared on SIGINT

    /*
    buddy_status
    Copyright (C) 2010  Belledonne Communications SARL

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
    */

    #ifdef IN_LINPHONE
    #include "linphonecore.h"
    #else
    #include "linphone/linphonecore.h"
    #endif

    #include <signal.h>

    static bool_t running=TRUE;

    static void stop(int signum){
            running=FALSE;
    }

    static void notify_presence_recv_updated (LinphoneCore *lc,  LinphoneFriend *friend) {
            const LinphoneAddress* friend_address = linphone_friend_get_address(friend);
            printf("New state state [%s] for user id [%s] \n"
                                    ,linphone_online_status_to_string(linphone_friend_get_status(friend))
                                    ,linphone_address_as_string (friend_address));
    }
    static void new_subscription_request (LinphoneCore *lc,  LinphoneFriend *friend, const char* url) {
            const LinphoneAddress* friend_address = linphone_friend_get_address(friend);
            printf(" [%s] wants to see your status, accepting\n"
                                    ,linphone_address_as_string (friend_address));
            linphone_friend_edit(friend); /* start editing friend */
            linphone_friend_set_inc_subscribe_policy(friend,LinphoneSPAccept); /* Accept incoming subscription request for this friend*/
            linphone_friend_done(friend); /*commit change*/
            linphone_core_add_friend(lc,friend); /* add this new friend to the buddy list*/

    }
    static void registration_state_changed(struct _LinphoneCore *lc, LinphoneProxyConfig *cfg, LinphoneRegistrationState cstate, const char *message){
                    printf("New registration state %s for user id [%s] at proxy [%s]\n"
                                    ,linphone_registration_state_to_string(cstate)
                                    ,linphone_proxy_config_get_identity(cfg)
                                    ,linphone_proxy_config_get_addr(cfg));
    }

    LinphoneCore *lc;
    int main(int argc, char *argv[]){
            LinphoneCoreVTable vtable={0};

            char* dest_friend=NULL;
            char* identity=NULL;
            char* password=NULL;

            /* takes   sip uri  identity from the command line arguments */
            if (argc>1){
                    dest_friend=argv[1];
            }
            /* takes   sip uri  identity from the command line arguments */
            if (argc>2){
                    identity=argv[2];
            }
            /* takes   password from the command line arguments */
            if (argc>3){
                    password=argv[3];
            }
            signal(SIGINT,stop);
    //#define DEBUG
    #ifdef DEBUG
            linphone_core_enable_logs(NULL); /*enable liblinphone logs.*/
    #endif
            /*
             Fill the LinphoneCoreVTable with application callbacks.
             All are optional. Here we only use the both notify_presence_recv and new_subscription_request callbacks
             in order to get notifications about friend status.
             */
            vtable.notify_presence_recv=notify_presence_recv_updated;
            vtable.new_subscription_request=new_subscription_request;
            vtable.registration_state_changed=registration_state_changed; /*just in case sip proxy is used*/

            /*
             Instantiate a LinphoneCore object given the LinphoneCoreVTable
            */
            lc=linphone_core_new(&vtable,NULL,NULL,NULL);
            /*sip proxy might be requested*/
            if (identity != NULL)  {
                    /*create proxy config*/
                    LinphoneProxyConfig* proxy_cfg = linphone_proxy_config_new();
                    /*parse identity*/
                    LinphoneAddress *from = linphone_address_new(identity);
                    if (from==NULL){
                            printf("%s not a valid sip uri, must be like sip:toto@sip.linphone.org \n",identity);
                            goto end;
                    }
                    LinphoneAuthInfo *info;
                    if (password!=NULL){
                            info=linphone_auth_info_new(linphone_address_get_username(from),NULL,password,NULL,NULL); /*create authentication structure from identity*/
                            linphone_core_add_auth_info(lc,info); /*add authentication info to LinphoneCore*/
                    }

                    // configure proxy entries
                    linphone_proxy_config_set_identity(proxy_cfg,identity); /*set identity with user name and domain*/
                    linphone_proxy_config_set_server_addr(proxy_cfg,linphone_address_get_domain(from)); /* we assume domain = proxy server address*/
                    linphone_proxy_config_enable_register(proxy_cfg,TRUE); /*activate registration for this proxy config*/
                    linphone_proxy_config_enable_publish(proxy_cfg,TRUE); /* enable presence satus publication for this proxy*/
                    linphone_address_destroy(from); /*release resource*/

                    linphone_core_add_proxy_config(lc,proxy_cfg); /*add proxy config to linphone core*/
                    linphone_core_set_default_proxy(lc,proxy_cfg); /*set to default proxy*/

                    /* Loop until registration status is available */
                    do {
                            linphone_core_iterate(lc); /* first iterate initiates registration */
                            ms_usleep(100000);
                    }
                    while(  running && linphone_proxy_config_get_state(proxy_cfg) == LinphoneRegistrationProgress);

            }
            LinphoneFriend* my_friend=NULL;

            if (dest_friend) {
                    my_friend = linphone_friend_new_with_addr(dest_friend); /*creates friend object from dest*/
                    if (my_friend == NULL) {
                            printf("bad destination uri for friend [%s]\n",dest_friend);
                            goto end;
                    }

                    linphone_friend_enable_subscribes(my_friend,TRUE); /*configure this friend to emit SUBSCRIBE message after being added to LinphoneCore*/
                    linphone_friend_set_inc_subscribe_policy(my_friend,LinphoneSPAccept); /* Accept incoming subscription request for this friend*/
                    linphone_core_add_friend(lc,my_friend); /* add my friend to the buddy list, initiate SUBSCRIBE message*/

            }

            linphone_core_set_presence_info(lc,0,NULL,LinphoneStatusOnline); /*set my status to online*/

            /* main loop for receiving notifications and doing background linphone core work: */
            while(running){
                    linphone_core_iterate(lc); /* first iterate initiates subscription */
                    ms_usleep(50000);
            }

            linphone_core_set_presence_info(lc,0,NULL,LinphoneStatusOffline); /* change my presence status to offline*/
            linphone_core_iterate(lc); /* just to make sure new status is initiate message is issued */

            linphone_friend_edit(my_friend); /* start editing friend */
            linphone_friend_enable_subscribes(my_friend,FALSE); /*disable subscription for this friend*/
            linphone_friend_done(my_friend); /*commit changes triggering an UNSUBSCRIBE message*/

            linphone_core_iterate(lc); /* just to make sure unsubscribe message is issued */

    end:
            printf("Shutting down...\n");
            linphone_core_destroy(lc);
            printf("Exited\n");
            return 0;
    }