sip_ua_layer.c

基于sip协议的网络电话源码

	    /* Unlock user agent. */
	    pj_mutex_unlock(mod_ua.mutex);
	}

    } else {
	/* Unlock user agent. */
	pj_mutex_unlock(mod_ua.mutex);
    }

    return dlg;
}


/*
 * Find the first dialog in dialog set in hash table for an incoming message.
 */
static struct dlg_set *find_dlg_set_for_msg( pjsip_rx_data *rdata )
{
    /* CANCEL message doesn't have To tag, so we must lookup the dialog
     * by finding the INVITE UAS transaction being cancelled.
     */
    if (rdata->msg_info.cseq->method.id == PJSIP_CANCEL_METHOD) {

	pjsip_dialog *dlg;

	/* Create key for the rdata, but this time, use INVITE as the
	 * method.
	 */
	pj_str_t key;
	pjsip_role_e role;
	pjsip_transaction *tsx;

	if (rdata->msg_info.msg->type == PJSIP_REQUEST_MSG)
	    role = PJSIP_ROLE_UAS;
	else
	    role = PJSIP_ROLE_UAC;

	pjsip_tsx_create_key(rdata->tp_info.pool, &key, role, 
			     &pjsip_invite_method, rdata);

	/* Lookup the INVITE transaction */
	tsx = pjsip_tsx_layer_find_tsx(&key, PJ_TRUE);

	/* We should find the dialog attached to the INVITE transaction */
	if (tsx) {
	    dlg = tsx->mod_data[mod_ua.mod.id];
	    pj_mutex_unlock(tsx->mutex);

	    /* Dlg may be NULL on some extreme condition
	     * (e.g. during debugging where initially there is a dialog)
	     */
	    return dlg ? dlg->dlg_set : NULL;

	} else {
	    return NULL;
	}


    } else {
	pj_str_t *tag;
	struct dlg_set *dlg_set;

	if (rdata->msg_info.msg->type == PJSIP_REQUEST_MSG)
	    tag = &rdata->msg_info.to->tag;
	else
	    tag = &rdata->msg_info.from->tag;

	/* Lookup the dialog set. */
	dlg_set = pj_hash_get(mod_ua.dlg_table, tag->ptr, tag->slen, NULL);
	return dlg_set;
    }
}

/* On received requests. */
static pj_bool_t mod_ua_on_rx_request(pjsip_rx_data *rdata)
{
    struct dlg_set *dlg_set;
    pj_str_t *from_tag;
    pjsip_dialog *dlg;
    pj_status_t status;

    /* Optimized path: bail out early if request is not CANCEL and it doesn't
     * have To tag 
     */
    if (rdata->msg_info.to->tag.slen == 0 && 
	rdata->msg_info.msg->line.req.method.id != PJSIP_CANCEL_METHOD)
    {
	return PJ_FALSE;
    }

retry_on_deadlock:

    /* Lock user agent before looking up the dialog hash table. */
    pj_mutex_lock(mod_ua.mutex);

    /* Lookup the dialog set, based on the To tag header. */
    dlg_set = find_dlg_set_for_msg(rdata);

    /* If dialog is not found, respond with 481 (Call/Transaction
     * Does Not Exist).
     */
    if (dlg_set == NULL) {
	/* Unable to find dialog. */
	pj_mutex_unlock(mod_ua.mutex);

	if (rdata->msg_info.msg->line.req.method.id != PJSIP_ACK_METHOD) {
	    PJ_LOG(5,(THIS_FILE, 
		      "Unable to find dialogset for %s, answering with 481",
		      pjsip_rx_data_get_info(rdata)));

	    /* Respond with 481 . */
	    pjsip_endpt_respond_stateless( mod_ua.endpt, rdata, 481, NULL, 
					   NULL, NULL );
	}
	return PJ_TRUE;
    }

    /* Dialog set has been found.
     * Find the dialog in the dialog set based on the content of the remote 
     * tag.
     */
    from_tag = &rdata->msg_info.from->tag;
    dlg = dlg_set->dlg_list.next;
    while (dlg != (pjsip_dialog*)&dlg_set->dlg_list) {
	
	if (pj_strcmp(&dlg->remote.info->tag, from_tag) == 0)
	    break;

	dlg = dlg->next;
    }

    /* Dialog may not be found, e.g. in this case:
     *	- UAC sends SUBSCRIBE, then UAS sends NOTIFY before answering
     *    SUBSCRIBE request with 2xx.
     *
     * In this case, we can accept the request ONLY when the original 
     * dialog still has empty To tag.
     */
    if (dlg == (pjsip_dialog*)&dlg_set->dlg_list) {

	pjsip_dialog *first_dlg = dlg_set->dlg_list.next;

	if (first_dlg->remote.info->tag.slen != 0) {
	    /* Not found. Mulfunction UAC? */
	    pj_mutex_unlock(mod_ua.mutex);

	    if (rdata->msg_info.msg->line.req.method.id != PJSIP_ACK_METHOD) {
		PJ_LOG(5,(THIS_FILE, 
		          "Unable to find dialog for %s, answering with 481",
		          pjsip_rx_data_get_info(rdata)));

		pjsip_endpt_respond_stateless(mod_ua.endpt, rdata,
					      PJSIP_SC_CALL_TSX_DOES_NOT_EXIST, 
					      NULL, NULL, NULL);
	    } else {
		PJ_LOG(5,(THIS_FILE, 
		          "Unable to find dialog for %s",
		          pjsip_rx_data_get_info(rdata)));
	    }
	    return PJ_TRUE;
	}

	dlg = first_dlg;
    }

    /* Mark the dialog id of the request. */
    rdata->endpt_info.mod_data[mod_ua.mod.id] = dlg;

    /* Try to lock the dialog */
    PJ_LOG(6,(dlg->obj_name, "UA layer acquiring dialog lock for request"));
    status = pjsip_dlg_try_inc_lock(dlg);
    if (status != PJ_SUCCESS) {
	/* Failed to acquire dialog mutex immediately, this could be 
	 * because of deadlock. Release UA mutex, yield, and retry 
	 * the whole thing once again.
	 */
	pj_mutex_unlock(mod_ua.mutex);
	pj_thread_sleep(0);
	goto retry_on_deadlock;
    }

    /* Done with processing in UA layer, release lock */
    pj_mutex_unlock(mod_ua.mutex);

    /* Pass to dialog. */
    pjsip_dlg_on_rx_request(dlg, rdata);

    /* Unlock the dialog. This may destroy the dialog */
    pjsip_dlg_dec_lock(dlg);

    /* Report as handled. */
    return PJ_TRUE;
}


/* On rx response notification.
 */
static pj_bool_t mod_ua_on_rx_response(pjsip_rx_data *rdata)
{
    pjsip_transaction *tsx;
    struct dlg_set *dlg_set;
    pjsip_dialog *dlg;
    pj_status_t status;

    /*
     * Find the dialog instance for the response.
     * All outgoing dialog requests are sent statefully, which means
     * there will be an UAC transaction associated with this response,
     * and the dialog instance will be recorded in that transaction.
     *
     * But even when transaction is found, there is possibility that
     * the response is a forked response.
     */

retry_on_deadlock:

    dlg = NULL;

    /* Lock user agent dlg table before we're doing anything. */
    pj_mutex_lock(mod_ua.mutex);

    /* Check if transaction is present. */
    tsx = pjsip_rdata_get_tsx(rdata);
    if (tsx) {
	/* Check if dialog is present in the transaction. */
	dlg = pjsip_tsx_get_dlg(tsx);
	if (!dlg) {
	    /* Unlock dialog hash table. */
	    pj_mutex_unlock(mod_ua.mutex);
	    return PJ_FALSE;
	}

	/* Get the dialog set. */
	dlg_set = dlg->dlg_set;

	/* Even if transaction is found and (candidate) dialog has been 
	 * identified, it's possible that the request has forked.
	 */

    } else {
	/* Transaction is not present.
	 * Check if this is a 2xx/OK response to INVITE, which in this
	 * case the response will be handled directly by the
	 * dialog.
	 */
	pjsip_cseq_hdr *cseq_hdr = rdata->msg_info.cseq;

	if (cseq_hdr->method.id != PJSIP_INVITE_METHOD ||
	    rdata->msg_info.msg->line.status.code / 100 != 2)
	{
	    /* Not a 2xx response to INVITE.
	     * This must be some stateless response sent by other modules,
	     * or a very late response.
	     */
	    /* Unlock dialog hash table. */
	    pj_mutex_unlock(mod_ua.mutex);
	    return PJ_FALSE;
	}


	/* Get the dialog set. */
	dlg_set = pj_hash_get(mod_ua.dlg_table, 
			      rdata->msg_info.from->tag.ptr,
			      rdata->msg_info.from->tag.slen,
			      NULL);

	if (!dlg_set) {
	    /* Unlock dialog hash table. */
	    pj_mutex_unlock(mod_ua.mutex);

	    /* Strayed 2xx response!! */
	    PJ_LOG(4,(THIS_FILE, 
		      "Received strayed 2xx response (no dialog is found)"
		      " from %s:%d: %s",
		      rdata->pkt_info.src_name, rdata->pkt_info.src_port,
		      pjsip_rx_data_get_info(rdata)));

	    return PJ_TRUE;
	}
    }

    /* At this point, we must have the dialog set, and the dialog set
     * must have a dialog in the list.
     */
    pj_assert(dlg_set && !pj_list_empty(&dlg_set->dlg_list));

    /* Check for forked response. 
     * Request will fork only for the initial INVITE request.
     */

    //This doesn't work when there is authentication challenge, since 
    //first_cseq evaluation will yield false.
    //if (rdata->msg_info.cseq->method.id == PJSIP_INVITE_METHOD &&
    //	rdata->msg_info.cseq->cseq == dlg_set->dlg_list.next->local.first_cseq)

    if (rdata->msg_info.cseq->method.id == PJSIP_INVITE_METHOD) {
	
	int st_code = rdata->msg_info.msg->line.status.code;
	pj_str_t *to_tag = &rdata->msg_info.to->tag;

	dlg = dlg_set->dlg_list.next;

	while (dlg != (pjsip_dialog*)&dlg_set->dlg_list) {

	    /* If there is dialog with no remote tag (i.e. dialog has not
	     * been established yet), then send this response to that
	     * dialog.
	     */
	    if (dlg->remote.info->tag.slen == 0)
		break;

	    /* Otherwise find the one with matching To tag. */
	    if (pj_strcmp(to_tag, &dlg->remote.info->tag) == 0)
		break;

	    dlg = dlg->next;
	}

	/* If no dialog with matching remote tag is found, this must be
	 * a forked response. Respond to this ONLY when response is non-100
	 * provisional response OR a 2xx response.
	 */
	if (dlg == (pjsip_dialog*)&dlg_set->dlg_list &&
	    ((st_code/100==1 && st_code!=100) || st_code/100==2)) 
	{

	    PJ_LOG(5,(THIS_FILE, 
		      "Received forked %s for existing dialog %s",
		      pjsip_rx_data_get_info(rdata), 
		      dlg_set->dlg_list.next->obj_name));

	    /* Report to application about forked condition.
	     * Application can either create a dialog or ignore the response.
	     */
	    if (mod_ua.param.on_dlg_forked) {
		dlg = (*mod_ua.param.on_dlg_forked)(dlg_set->dlg_list.next, 
						    rdata);
	    } else {
		dlg = dlg_set->dlg_list.next;

		PJ_LOG(4,(THIS_FILE, 
			  "Unhandled forked %s from %s:%d, response will be "
			  "handed over to the first dialog",
			  pjsip_rx_data_get_info(rdata),
			  rdata->pkt_info.src_name, rdata->pkt_info.src_port));
	    }

	} else if (dlg == (pjsip_dialog*)&dlg_set->dlg_list) {

	    /* For 100 or non-2xx response which has different To tag,
	     * pass the response to the first dialog.
	     */

	    dlg = dlg_set->dlg_list.next;

	}

    } else {
	/* Either this is a non-INVITE response, or subsequent INVITE
	 * within dialog. The dialog should have been identified when
	 * the transaction was found.
	 */
	pj_assert(tsx != NULL);
	pj_assert(dlg != NULL);
    }

    /* The dialog must have been found. */
    pj_assert(dlg != NULL);

    /* Put the dialog instance in the rdata. */
    rdata->endpt_info.mod_data[mod_ua.mod.id] = dlg;

    /* Attempt to acquire lock to the dialog. */
    PJ_LOG(6,(dlg->obj_name, "UA layer acquiring dialog lock for response"));
    status = pjsip_dlg_try_inc_lock(dlg);
    if (status != PJ_SUCCESS) {
	/* Failed to acquire dialog mutex. This could indicate a deadlock
	 * situation, and for safety, try to avoid deadlock by releasing
	 * UA mutex, yield, and retry the whole processing once again.
	 */
	pj_mutex_unlock(mod_ua.mutex);
	pj_thread_sleep(0);
	goto retry_on_deadlock;
    }

    /* We're done with processing in the UA layer, we can release the mutex */
    pj_mutex_unlock(mod_ua.mutex);

    /* Pass the response to the dialog. */
    pjsip_dlg_on_rx_response(dlg, rdata);

    /* Unlock the dialog. This may destroy the dialog. */
    pjsip_dlg_dec_lock(dlg);

    /* Done. */
    return PJ_TRUE;
}


#if PJ_LOG_MAX_LEVEL >= 3
static void print_dialog( const char *title,
			  pjsip_dialog *dlg, char *buf, pj_size_t size)
{
    int len;
    char userinfo[128];

    len = pjsip_hdr_print_on(dlg->remote.info, userinfo, sizeof(userinfo));
    if (len < 1)
	pj_ansi_strcpy(userinfo, "<--uri too long-->");
    else
	userinfo[len] = '\0';
    
    len = pj_ansi_snprintf(buf, size, "%s[%s]  %s",
			   title,
			   (dlg->state==PJSIP_DIALOG_STATE_NULL ? " - " :
							     "est"),
		      userinfo);
    if (len < 1 || len >= (int)size) {
	pj_ansi_strcpy(buf, "<--uri too long-->");
    } else
	buf[len] = '\0';
}
#endif

/*
 * Dump user agent contents (e.g. all dialogs).
 */
PJ_DEF(void) pjsip_ua_dump(pj_bool_t detail)
{
#if PJ_LOG_MAX_LEVEL >= 3
    pj_hash_iterator_t itbuf, *it;
    char dlginfo[128];

    pj_mutex_lock(mod_ua.mutex);

    PJ_LOG(3, (THIS_FILE, "Number of dialog sets: %u", 
			  pj_hash_count(mod_ua.dlg_table)));

    if (detail && pj_hash_count(mod_ua.dlg_table)) {
	PJ_LOG(3, (THIS_FILE, "Dumping dialog sets:"));
	it = pj_hash_first(mod_ua.dlg_table, &itbuf);
	for (; it != NULL; it = pj_hash_next(mod_ua.dlg_table, it))  {
	    struct dlg_set *dlg_set;
	    pjsip_dialog *dlg;
	    const char *title;

	    dlg_set = pj_hash_this(mod_ua.dlg_table, it);
	    if (!dlg_set || pj_list_empty(&dlg_set->dlg_list)) continue;

	    /* First dialog in dialog set. */
	    dlg = dlg_set->dlg_list.next;
	    if (dlg->role == PJSIP_ROLE_UAC)
		title = "  [out] ";
	    else
		title = "  [in]  ";

	    print_dialog(title, dlg, dlginfo, sizeof(dlginfo));
	    PJ_LOG(3,(THIS_FILE, "%s", dlginfo));

	    /* Next dialog in dialog set (forked) */
	    dlg = dlg->next;
	    while (dlg != (pjsip_dialog*) &dlg_set->dlg_list) {
		print_dialog("    [forked] ", dlg, dlginfo, sizeof(dlginfo));
		dlg = dlg->next;
	    }
	}
    }

    pj_mutex_unlock(mod_ua.mutex);
#endif
}