#if 0  typedef struct osip_statemachine osip_statemachine_t;  struct osip_statemachine  {    osip_list_t *transitions;  };#endif/** * Enumeration for transaction type. * A transaction can be either of: *  ICT, *  IST, *  NICT, *  NIST, */  typedef enum osip_fsm_type_t  {    ICT, /**< Invite Client (outgoing) Transaction */    IST, /**< Invite Server (incoming) Transaction */    NICT,/**< Non-Invite Client (outgoing) Transaction */    NIST /**< Non-Invite Server (incoming) Transaction */  }  osip_fsm_type_t;#ifndef DEFAULT_T1/** * You can re-define the default value for T1. (T1 is defined in rfcxxxx) * The default value is 500ms. */#define DEFAULT_T1 500		/* 500 ms */#endif#ifndef DEFAULT_T2/** * You can re-define the default value for T2. (T2 is defined in rfcxxxx) * The default value is 4000ms. */#define DEFAULT_T2 4000		/* 4s */#endif#ifndef DEFAULT_T4/** * You can re-define the default value for T4. (T1 is defined in rfcxxxx) * The default value is 5000ms. */#define DEFAULT_T4 5000		/* 5s */#endif/** * Structure for INVITE CLIENT TRANSACTION (outgoing INVITE transaction). * @defvar osip_ict_t */  typedef struct osip_ict osip_ict_t;  struct osip_ict  {    /* state machine is implied... */    int timer_a_length;	   /* A=T1, A=2xT1... (unreliable transport only)  */    time_t timer_a_start;    int timer_b_length;	   /* B = 64* T1                                   */    time_t timer_b_start;  /* fire when transaction timeouts               */    int timer_d_length;    /* D >= 32s for unreliable transport (else = 0) */    time_t timer_d_start;  /* should be equal to timer H */    char *destination;	   /* url used to send requests         */    int port;		   /* port of next hop                  */  };/** * Structure for NON-INVITE CLIENT TRANSACTION (outgoing NON-INVITE transaction). * @defvar osip_nict_t */  typedef struct osip_nict osip_nict_t;  struct osip_nict  {    /* state machine is implied... */    int timer_e_length;    /* A=T1, A=2xT1... (unreliable transport only)  */    time_t timer_e_start;  /*  (else = -1) not active                      */    int timer_f_length;	   /* B = 64* T1                                   */    time_t timer_f_start;  /* fire when transaction timeouts               */    int timer_k_length;	   /* K = T4 (else = 0)                            */    time_t timer_k_start;    char *destination;	   /* url used to send requests         */    int port;		   /* port of next hop                  */  };/** * Structure for INVITE SERVER TRANSACTION (incoming INVITE transaction). * @defvar osip_ist_t */  typedef struct osip_ist osip_ist_t;  struct osip_ist  {    int timer_g_length;   /* G=MIN(T1*2,T2) for unreliable transport    */    time_t timer_g_start; /* else = 0 when reliable transport is used!  */    int timer_h_length;	  /* H = 64* T1                                 */    time_t timer_h_start; /* fire when if no ACK is received            */    int timer_i_length;	  /* I = T4 for unreliable transport (else = 0) */    time_t timer_i_start; /* absorb all ACK                             */  };/** * Structure for NON-INVITE SERVER TRANSACTION (incoming SERVER transaction). * @defvar osip_nist_t */  typedef struct osip_nist osip_nist_t;  struct osip_nist  {    int timer_j_length;		/* J = 64*T1 (else 0) */    time_t timer_j_start;  };/** * Structure for transaction handling. * @defvar osip_transaction_t */  typedef struct osip_transaction osip_transaction_t;  struct osip_transaction  {    void *your_instance;	/* add whatever you want here.       */    int transactionid;		/* simple id used to identify the tr. */    osip_fifo_t *transactionff;	/* events must be added in this fifo */    osip_via_t *topvia;		/* CALL-LEG definition */    osip_from_t *from;		/* CALL-LEG definition */    osip_to_t *to;    osip_call_id_t *callid;    osip_cseq_t *cseq;    osip_message_t *orig_request;	/* last request sent                 */    osip_message_t *last_response;	/* last response received            */    osip_message_t *ack;			/* ack request sent                  */    state_t state;		/* state of transaction              */    time_t birth_time;		/* birth_date of transaction         */    time_t completed_time;	/* end   date of transaction         */    /* RESPONSE are received on this socket */    int in_socket;    /* REQUESTS are sent on this socket */    int out_socket;    void *config;		/* transaction is managed by config  */    osip_fsm_type_t ctx_type;    osip_ict_t *ict_context;    osip_ist_t *ist_context;    osip_nict_t *nict_context;    osip_nist_t *nist_context;  };  typedef enum osip_message_callback_type {    OSIP_ICT_INVITE_SENT = 0,    OSIP_ICT_INVITE_SENT_AGAIN,    OSIP_ICT_ACK_SENT,    OSIP_ICT_ACK_SENT_AGAIN,    OSIP_ICT_STATUS_1XX_RECEIVED,    OSIP_ICT_STATUS_2XX_RECEIVED,    OSIP_ICT_STATUS_2XX_RECEIVED_AGAIN,    OSIP_ICT_STATUS_3XX_RECEIVED,    OSIP_ICT_STATUS_4XX_RECEIVED,    OSIP_ICT_STATUS_5XX_RECEIVED,    OSIP_ICT_STATUS_6XX_RECEIVED,    OSIP_ICT_STATUS_3456XX_RECEIVED_AGAIN,    OSIP_IST_INVITE_RECEIVED,    OSIP_IST_INVITE_RECEIVED_AGAIN,    OSIP_IST_ACK_RECEIVED,    OSIP_IST_ACK_RECEIVED_AGAIN,    OSIP_IST_STATUS_1XX_SENT,    OSIP_IST_STATUS_2XX_SENT,    OSIP_IST_STATUS_2XX_SENT_AGAIN,    OSIP_IST_STATUS_3XX_SENT,    OSIP_IST_STATUS_4XX_SENT,    OSIP_IST_STATUS_5XX_SENT,    OSIP_IST_STATUS_6XX_SENT,    OSIP_IST_STATUS_3456XX_SENT_AGAIN,    OSIP_NICT_REGISTER_SENT,    OSIP_NICT_BYE_SENT,    OSIP_NICT_OPTIONS_SENT,    OSIP_NICT_INFO_SENT,    OSIP_NICT_CANCEL_SENT,    OSIP_NICT_NOTIFY_SENT,    OSIP_NICT_SUBSCRIBE_SENT,    OSIP_NICT_UNKNOWN_REQUEST_SENT,    OSIP_NICT_REQUEST_SENT_AGAIN,    OSIP_NICT_STATUS_1XX_RECEIVED,    OSIP_NICT_STATUS_2XX_RECEIVED,    OSIP_NICT_STATUS_2XX_RECEIVED_AGAIN,    OSIP_NICT_STATUS_3XX_RECEIVED,    OSIP_NICT_STATUS_4XX_RECEIVED,    OSIP_NICT_STATUS_5XX_RECEIVED,    OSIP_NICT_STATUS_6XX_RECEIVED,    OSIP_NICT_STATUS_3456XX_RECEIVED_AGAIN,    OSIP_NIST_REGISTER_RECEIVED,    OSIP_NIST_BYE_RECEIVED,    OSIP_NIST_OPTIONS_RECEIVED,    OSIP_NIST_INFO_RECEIVED,    OSIP_NIST_CANCEL_RECEIVED,    OSIP_NIST_NOTIFY_RECEIVED,    OSIP_NIST_SUBSCRIBE_RECEIVED,    /* ... TO BE ADDED: All known and used method extensions */    OSIP_NIST_UNKNOWN_REQUEST_RECEIVED,    OSIP_NIST_REQUEST_RECEIVED_AGAIN,    OSIP_NIST_STATUS_1XX_SENT,    OSIP_NIST_STATUS_2XX_SENT,    OSIP_NIST_STATUS_2XX_SENT_AGAIN,    OSIP_NIST_STATUS_3XX_SENT,    OSIP_NIST_STATUS_4XX_SENT,    OSIP_NIST_STATUS_5XX_SENT,    OSIP_NIST_STATUS_6XX_SENT,    OSIP_NIST_STATUS_3456XX_SENT_AGAIN,    OSIP_MESSAGE_CALLBACK_COUNT  } osip_message_callback_type_t;  typedef enum osip_kill_callback_type {    OSIP_ICT_KILL_TRANSACTION,    OSIP_IST_KILL_TRANSACTION,    OSIP_NICT_KILL_TRANSACTION,    OSIP_NIST_KILL_TRANSACTION,    OSIP_KILL_CALLBACK_COUNT  } osip_kill_callback_type_t;  typedef enum osip_transport_error_callback_type {    OSIP_ICT_TRANSPORT_ERROR,    OSIP_IST_TRANSPORT_ERROR,    OSIP_NICT_TRANSPORT_ERROR,    OSIP_NIST_TRANSPORT_ERROR,    OSIP_TRANSPORT_ERROR_CALLBACK_COUNT  } osip_transport_error_callback_type_t;  typedef void (* osip_message_cb_t) (int type, osip_transaction_t *, osip_message_t *);  typedef void (* osip_kill_transaction_cb_t) (int type, osip_transaction_t *);  typedef void (* osip_transport_error_cb_t) (int type, osip_transaction_t *,					      int error);#ifdef OSIP_RETRANSMIT_2XX  struct osip_dialog;  typedef struct ixt_t ixt_t;  struct ixt_t  {    /* any ACK received that match this context will set counter to -1*/    struct osip_dialog *dialog;    osip_message_t *msg2xx;    /* copy of string to retransmit */    osip_message_t *ack;       /* useless for ist */    time_t start;    int interval;     /* between each retransmission, in ms */    char *dest;    int port;    int sock;    int counter;      /* start at 7 */  };#endif/** * Structure for osip handling. * In order to use osip, you have to manage at least one global instance * of an osip_t element. Then, you'll register a set of required callbacks * and a set of optional ones. * @defvar osip_t */  typedef struct osip osip_t;  struct osip  {    void *application_context;	/* a pointer for your personnal usage */    /* list of transactions for ict, ist, nict, nist */    osip_list_t *osip_ict_transactions;    osip_list_t *osip_ist_transactions;    osip_list_t *osip_nict_transactions;    osip_list_t *osip_nist_transactions;        osip_list_t *ixt_retransmissions; /* for retransmission of 2xx & ACK for INVITE */    osip_message_cb_t msg_callbacks[OSIP_MESSAGE_CALLBACK_COUNT];    osip_kill_transaction_cb_t kill_callbacks[OSIP_KILL_CALLBACK_COUNT];    osip_transport_error_cb_t tp_error_callbacks[OSIP_TRANSPORT_ERROR_CALLBACK_COUNT];    /* callbacks for sending messages */    int (*cb_send_message) (osip_transaction_t *, osip_message_t *, char *, int, int);  };  int osip_set_message_callback (osip_t *, int type, osip_message_cb_t cb);  int osip_set_kill_transaction_callback (osip_t *, int type,					  osip_kill_transaction_cb_t cb);  int osip_set_transport_error_callback (osip_t *, int type,					 osip_transport_error_cb_t cb);/** * Structure for sipevent handling. * A osip_event_t element will have a type and will be related * to a transaction. In the general case, it is used by the * application layer to give SIP messages to the oSIP finite * state machine. * @defvar osip_event_t */  typedef struct osip_event osip_event_t;  struct osip_event  {    type_t type;    int transactionid;    osip_message_t *sip;  };/** * Allocate an osip_transaction_t element. * @param transaction The element to allocate. * @param ctx_type The type of transaction. (ICT, IST, NICT, NIST) * @param osip The global instance of oSIP. * @param request The SIP request that initiate the transaction. */  int osip_transaction_init (osip_transaction_t ** transaction, osip_fsm_type_t ctx_type,			     osip_t * osip, osip_message_t * request);/** * Free all resource in a osip_transaction_t element. * @param transaction The element to free. */  int osip_transaction_free (osip_transaction_t * transaction);/** * Free all resource in a osip_transaction_t element. * This method does the same than osip_transaction_free() but it assumes * that the transaction is already removed from the list of transaction * in the osip stack. (to remove it use osip_xixt_remove(osip, transaction); * @param transaction The element to free. */  int osip_transaction_free2 (osip_transaction_t * transaction);/** * Set the host and port destination used for sending the SIP message. * This can be useful for an application with 'DIRECT ROOTING MODE' * NOTE: Instead, you should use the 'Route' header facility which * leads to the same behaviour. * @param ict The element to work on. * @param destination The destination host. * @param port The destination port. */  int osip_ict_set_destination (osip_ict_t * ict, char *destination, int port);/** * Set the host and port destination used for sending the SIP message. * This can be useful for an application with 'DIRECT ROOTING MODE' * NOTE: Instead, you should use the 'Route' header facility which * leads to the same behaviour. * @param nict The element to work on. * @param destination The destination host. * @param port The destination port. */  int osip_nict_set_destination (osip_nict_t * nict, char *destination, int port);/** * Add a SIP event in the fifo of a osip_transaction_t element. * @param transaction The element to work on. * @param evt The event to add. */  int osip_transaction_add_event (osip_transaction_t * transaction, osip_event_t * evt);/** * Consume one osip_event_t element previously added in the fifo.