7fe50a311f
In order to be able to protect the interface so that mistyped argument do not endanger MaxScale yet still allow the developer access a router option has been added that gives the debugcli two modes.
470 lines
12 KiB
C
470 lines
12 KiB
C
/*
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* This file is distributed as part of the SkySQL Gateway. It is free
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* software: you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation,
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* version 2.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Copyright SkySQL Ab 2013
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*/
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/**
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* @file session.c - A representation of the session within the gateway.
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*
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* @verbatim
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* Revision History
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*
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* Date Who Description
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* 17/06/13 Mark Riddoch Initial implementation
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* 02/09/13 Massimiliano Pinto Added session refcounter
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*
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* @endverbatim
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include <session.h>
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#include <service.h>
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#include <router.h>
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#include <dcb.h>
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#include <spinlock.h>
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#include <atomic.h>
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#include <skygw_utils.h>
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#include <log_manager.h>
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extern int lm_enabled_logfiles_bitmask;
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static SPINLOCK session_spin = SPINLOCK_INIT;
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static SESSION *allSessions = NULL;
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/**
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* Allocate a new session for a new client of the specified service.
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*
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* Create the link to the router session by calling the newSession
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* entry point of the router using the router instance of the
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* service this session is part of.
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*
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* @param service The service this connection was established by
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* @param client_dcb The client side DCB
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* @return The newly created session or NULL if an error occured
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*/
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SESSION *
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session_alloc(SERVICE *service, DCB *client_dcb)
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{
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SESSION *session;
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session = (SESSION *)calloc(1, sizeof(SESSION));
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ss_info_dassert(session != NULL,
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"Allocating memory for session failed.");
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if (session == NULL) {
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int eno = errno;
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errno = 0;
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LOGIF(LE, (skygw_log_write_flush(
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LOGFILE_ERROR,
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"Error : Failed to allocate memory for "
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"session object due error %d, %s.",
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eno,
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strerror(eno))));
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goto return_session;
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}
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#if defined(SS_DEBUG)
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session->ses_chk_top = CHK_NUM_SESSION;
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session->ses_chk_tail = CHK_NUM_SESSION;
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#endif
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spinlock_init(&session->ses_lock);
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/*<
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* Prevent backend threads from accessing before session is completely
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* initialized.
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*/
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spinlock_acquire(&session->ses_lock);
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session->service = service;
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session->client = client_dcb;
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memset(&session->stats, 0, sizeof(SESSION_STATS));
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session->stats.connect = time(0);
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session->state = SESSION_STATE_ALLOC;
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/*<
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* Associate the session to the client DCB and set the reference count on
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* the session to indicate that there is a single reference to the
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* session. There is no need to protect this or use atomic add as the
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* session has not been made available to the other threads at this
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* point.
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*/
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session->data = client_dcb->data;
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client_dcb->session = session;
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session->refcount = 1;
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/*<
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* This indicates that session is ready to be shared with backend
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* DCBs. Note that this doesn't mean that router is initialized yet!
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*/
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session->state = SESSION_STATE_READY;
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/*< Release session lock */
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spinlock_release(&session->ses_lock);
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/*
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* Only create a router session if we are not the listening
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* DCB or an internal DCB. Creating a router session may create a connection to a
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* backend server, depending upon the router module implementation
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* and should be avoided for the listener session
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*
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* Router session creation may create other DCBs that link to the
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* session, therefore it is important that the session lock is
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* relinquished beforethe router call.
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*/
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if (client_dcb->state != DCB_STATE_LISTENING && client_dcb->dcb_role != DCB_ROLE_INTERNAL)
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{
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session->router_session =
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service->router->newSession(service->router_instance,
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session);
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if (session->router_session == NULL) {
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/*<
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* Decrease refcount, set dcb's session pointer NULL
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* and set session pointer to NULL.
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*/
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session_free(session);
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client_dcb->session = NULL;
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session = NULL;
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LOGIF(LE, (skygw_log_write_flush(
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LOGFILE_ERROR,
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"Error : Failed to create router "
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"client session. Freeing allocated resources.")));
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goto return_session;
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}
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}
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spinlock_acquire(&session_spin);
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session->state = SESSION_STATE_ROUTER_READY;
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session->next = allSessions;
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allSessions = session;
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spinlock_release(&session_spin);
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atomic_add(&service->stats.n_sessions, 1);
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atomic_add(&service->stats.n_current, 1);
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CHK_SESSION(session);
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return_session:
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return session;
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}
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/**
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* Link a session to a DCB.
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*
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* @param session The session to link with the dcb
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* @param dcb The DCB to be linked
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* @return True if the session was sucessfully linked to the DCB
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*/
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bool
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session_link_dcb(SESSION *session, DCB *dcb)
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{
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spinlock_acquire(&session->ses_lock);
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ss_info_dassert(session->state != SESSION_STATE_FREE,
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"If session->state is SESSION_STATE_FREE then this attempt to "
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"access freed memory block.");
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if (session->state == SESSION_STATE_FREE)
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{
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spinlock_release(&session->ses_lock);
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return false;
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}
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atomic_add(&session->refcount, 1);
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dcb->session = session;
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spinlock_release(&session->ses_lock);
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return true;
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}
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int session_unlink_dcb(
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SESSION* session,
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DCB* dcb)
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{
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int nlink;
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CHK_SESSION(session);
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spinlock_acquire(&session->ses_lock);
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ss_dassert(session->refcount > 0);
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/*<
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* Remove dcb from session's router_client_session.
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*/
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nlink = atomic_add(&session->refcount, -1);
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nlink -= 1;
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if (nlink == 0)
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{
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session->state = SESSION_STATE_FREE;
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}
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if (dcb != NULL)
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{
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dcb->session = NULL;
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}
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spinlock_release(&session->ses_lock);
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return nlink;
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}
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/**
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* Deallocate the specified session
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*
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* @param session The session to deallocate
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*/
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bool session_free(
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SESSION *session)
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{
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bool succp = false;
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SESSION *ptr;
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int nlink;
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CHK_SESSION(session);
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/*<
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* Remove one reference. If there are no references left,
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* free session.
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*/
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nlink = session_unlink_dcb(session, NULL);
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if (nlink != 0) {
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ss_dassert(nlink > 0);
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goto return_succp;
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}
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/* First of all remove from the linked list */
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spinlock_acquire(&session_spin);
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if (allSessions == session)
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{
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allSessions = session->next;
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}
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else
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{
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ptr = allSessions;
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while (ptr && ptr->next != session)
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{
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ptr = ptr->next;
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}
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if (ptr)
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ptr->next = session->next;
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}
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spinlock_release(&session_spin);
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atomic_add(&session->service->stats.n_current, -1);
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/* Free router_session and session */
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if (session->router_session) {
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session->service->router->freeSession(
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session->service->router_instance,
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session->router_session);
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}
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free(session);
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succp = true;
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return_succp :
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return succp;
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}
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/**
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* Check to see if a session is valid, i.e. in the list of all sessions
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*
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* @param session Session to check
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* @return 1 if the session is valid otherwise 0
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*/
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int
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session_isvalid(SESSION *session)
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{
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SESSION *ptr;
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int rval = 0;
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spinlock_acquire(&session_spin);
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ptr = allSessions;
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while (ptr)
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{
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if (ptr == session)
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{
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rval = 1;
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break;
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}
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ptr = ptr->next;
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}
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spinlock_release(&session_spin);
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return rval;
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}
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/**
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* Print details of an individual session
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*
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* @param session Session to print
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*/
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void
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printSession(SESSION *session)
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{
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printf("Session %p\n", session);
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printf("\tState: %s\n", session_state(session->state));
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printf("\tService: %s (%p)\n", session->service->name, session->service);
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printf("\tClient DCB: %p\n", session->client);
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printf("\tConnected: %s", asctime(localtime(&session->stats.connect)));
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}
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/**
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* Print all sessions
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*
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* Designed to be called within a debugger session in order
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* to display all active sessions within the gateway
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*/
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void
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printAllSessions()
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{
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SESSION *ptr;
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spinlock_acquire(&session_spin);
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ptr = allSessions;
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while (ptr)
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{
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printSession(ptr);
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ptr = ptr->next;
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}
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spinlock_release(&session_spin);
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}
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/**
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* Check sessions
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*
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* Designed to be called within a debugger session in order
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* to display information regarding "interesting" sessions
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*/
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void
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CheckSessions()
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{
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SESSION *ptr;
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int noclients = 0;
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int norouter = 0;
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spinlock_acquire(&session_spin);
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ptr = allSessions;
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while (ptr)
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{
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if (ptr->state != SESSION_STATE_LISTENER ||
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ptr->state != SESSION_STATE_LISTENER_STOPPED)
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{
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if (ptr->client == NULL && ptr->refcount)
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{
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if (noclients == 0)
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{
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printf("Sessions without a client DCB.\n");
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printf("==============================\n");
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}
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printSession(ptr);
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noclients++;
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}
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}
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ptr = ptr->next;
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}
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spinlock_release(&session_spin);
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if (noclients)
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printf("%d Sessions have no clients\n", noclients);
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spinlock_acquire(&session_spin);
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ptr = allSessions;
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while (ptr)
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{
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if (ptr->state != SESSION_STATE_LISTENER ||
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ptr->state != SESSION_STATE_LISTENER_STOPPED)
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{
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if (ptr->router_session == NULL && ptr->refcount)
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{
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if (norouter == 0)
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{
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printf("Sessions without a router session.\n");
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printf("==================================\n");
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}
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printSession(ptr);
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norouter++;
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}
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}
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ptr = ptr->next;
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}
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spinlock_release(&session_spin);
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if (norouter)
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printf("%d Sessions have no router session\n", norouter);
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}
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/**
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* Print all sessions to a DCB
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*
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* Designed to be called within a debugger session in order
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* to display all active sessions within the gateway
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*
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* @param dcb The DCB to print to
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*/
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void
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dprintAllSessions(DCB *dcb)
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{
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SESSION *ptr;
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spinlock_acquire(&session_spin);
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ptr = allSessions;
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while (ptr)
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{
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dcb_printf(dcb, "Session %p\n", ptr);
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dcb_printf(dcb, "\tState: %s\n", session_state(ptr->state));
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dcb_printf(dcb, "\tService: %s (%p)\n", ptr->service->name, ptr->service);
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dcb_printf(dcb, "\tClient DCB: %p\n", ptr->client);
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if (ptr->client && ptr->client->remote)
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dcb_printf(dcb, "\tClient Address: %s\n", ptr->client->remote);
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dcb_printf(dcb, "\tConnected: %s", asctime(localtime(&ptr->stats.connect)));
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ptr = ptr->next;
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}
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spinlock_release(&session_spin);
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}
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/**
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* Print a particular session to a DCB
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*
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* Designed to be called within a debugger session in order
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* to display all active sessions within the gateway
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*
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* @param dcb The DCB to print to
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* @param ptr The session to print
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*/
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void
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dprintSession(DCB *dcb, SESSION *ptr)
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{
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dcb_printf(dcb, "Session %p\n", ptr);
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dcb_printf(dcb, "\tState: %s\n", session_state(ptr->state));
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dcb_printf(dcb, "\tService: %s (%p)\n", ptr->service->name, ptr->service);
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dcb_printf(dcb, "\tClient DCB: %p\n", ptr->client);
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if (ptr->client && ptr->client->remote)
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dcb_printf(dcb, "\tClient Address: %s\n", ptr->client->remote);
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dcb_printf(dcb, "\tConnected: %s", asctime(localtime(&ptr->stats.connect)));
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}
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/**
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* Convert a session state to a string representation
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*
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* @param state The session state
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* @return A string representation of the session state
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*/
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char *
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session_state(int state)
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{
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switch (state)
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{
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case SESSION_STATE_ALLOC:
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return "Session Allocated";
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case SESSION_STATE_READY:
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return "Session Ready";
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case SESSION_STATE_LISTENER:
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return "Listener Session";
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case SESSION_STATE_LISTENER_STOPPED:
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return "Stopped Listener Session";
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default:
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return "Invalid State";
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}
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}
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