lwip_timeouts.c

00001 /**
00002  * @file
00003  * Stack-internal timers implementation.
00004  * This file includes timer callbacks for stack-internal timers as well as
00005  * functions to set up or stop timers and check for expired timers.
00006  *
00007  */
00008 
00009 /*
00010  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00011  * All rights reserved.
00012  *
00013  * Redistribution and use in source and binary forms, with or without modification,
00014  * are permitted provided that the following conditions are met:
00015  *
00016  * 1. Redistributions of source code must retain the above copyright notice,
00017  *    this list of conditions and the following disclaimer.
00018  * 2. Redistributions in binary form must reproduce the above copyright notice,
00019  *    this list of conditions and the following disclaimer in the documentation
00020  *    and/or other materials provided with the distribution.
00021  * 3. The name of the author may not be used to endorse or promote products
00022  *    derived from this software without specific prior written permission.
00023  *
00024  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00025  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00026  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00027  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00028  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00029  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00030  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00031  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00032  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00033  * OF SUCH DAMAGE.
00034  *
00035  * This file is part of the lwIP TCP/IP stack.
00036  *
00037  * Author: Adam Dunkels <adam@sics.se>
00038  *         Simon Goldschmidt
00039  *
00040  */
00041 
00042 #include "lwip/opt.h"
00043 
00044 #include "lwip/timeouts.h"
00045 #include "lwip/priv/tcp_priv.h"
00046 
00047 #include "lwip/def.h"
00048 #include "lwip/memp.h"
00049 #include "lwip/priv/tcpip_priv.h"
00050 
00051 #include "lwip/ip4_frag.h"
00052 #include "lwip/etharp.h"
00053 #include "lwip/dhcp.h"
00054 #include "lwip/autoip.h"
00055 #include "lwip/igmp.h"
00056 #include "lwip/dns.h"
00057 #include "lwip/nd6.h"
00058 #include "lwip/ip6_frag.h"
00059 #include "lwip/mld6.h"
00060 #include "lwip/sys.h"
00061 #include "lwip/pbuf.h"
00062 
00063 #if LWIP_DEBUG_TIMERNAMES
00064 #define HANDLER(x) x, #x
00065 #else /* LWIP_DEBUG_TIMERNAMES */
00066 #define HANDLER(x) x
00067 #endif /* LWIP_DEBUG_TIMERNAMES */
00068 
00069 /** This array contains all stack-internal cyclic timers. To get the number of
00070  * timers, use LWIP_ARRAYSIZE() */
00071 const struct lwip_cyclic_timer lwip_cyclic_timers[] = {
00072 #if LWIP_TCP
00073   /* The TCP timer is a special case: it does not have to run always and
00074      is triggered to start from TCP using tcp_timer_needed() */
00075   {TCP_TMR_INTERVAL, HANDLER(tcp_tmr)},
00076 #endif /* LWIP_TCP */
00077 #if LWIP_IPV4
00078 #if IP_REASSEMBLY
00079   {IP_TMR_INTERVAL, HANDLER(ip_reass_tmr)},
00080 #endif /* IP_REASSEMBLY */
00081 #if LWIP_ARP
00082   {ARP_TMR_INTERVAL, HANDLER(etharp_tmr)},
00083 #endif /* LWIP_ARP */
00084 #if LWIP_DHCP
00085   {DHCP_COARSE_TIMER_MSECS, HANDLER(dhcp_coarse_tmr)},
00086   {DHCP_FINE_TIMER_MSECS, HANDLER(dhcp_fine_tmr)},
00087 #endif /* LWIP_DHCP */
00088 #if LWIP_AUTOIP
00089   {AUTOIP_TMR_INTERVAL, HANDLER(autoip_tmr)},
00090 #endif /* LWIP_AUTOIP */
00091 #if LWIP_IGMP
00092   {IGMP_TMR_INTERVAL, HANDLER(igmp_tmr)},
00093 #endif /* LWIP_IGMP */
00094 #endif /* LWIP_IPV4 */
00095 #if LWIP_DNS
00096   {DNS_TMR_INTERVAL, HANDLER(dns_tmr)},
00097 #endif /* LWIP_DNS */
00098 #if LWIP_IPV6
00099   {ND6_TMR_INTERVAL, HANDLER(nd6_tmr)},
00100 #if LWIP_IPV6_REASS
00101   {IP6_REASS_TMR_INTERVAL, HANDLER(ip6_reass_tmr)},
00102 #endif /* LWIP_IPV6_REASS */
00103 #if LWIP_IPV6_MLD
00104   {MLD6_TMR_INTERVAL, HANDLER(mld6_tmr)},
00105 #endif /* LWIP_IPV6_MLD */
00106 #endif /* LWIP_IPV6 */
00107 };
00108 
00109 #if LWIP_TIMERS && !LWIP_TIMERS_CUSTOM
00110 
00111 /** The one and only timeout list */
00112 static struct sys_timeo *next_timeout;
00113 static u32_t timeouts_last_time;
00114 
00115 #if LWIP_TCP
00116 /** global variable that shows if the tcp timer is currently scheduled or not */
00117 static int tcpip_tcp_timer_active;
00118 
00119 /**
00120  * Timer callback function that calls tcp_tmr() and reschedules itself.
00121  *
00122  * @param arg unused argument
00123  */
00124 static void
00125 tcpip_tcp_timer(void *arg)
00126 {
00127   LWIP_UNUSED_ARG(arg);
00128 
00129   /* call TCP timer handler */
00130   tcp_tmr();
00131   /* timer still needed? */
00132   if (tcp_active_pcbs || tcp_tw_pcbs) {
00133     /* restart timer */
00134     sys_timeout(TCP_TMR_INTERVAL, tcpip_tcp_timer, NULL);
00135   } else {
00136     /* disable timer */
00137     tcpip_tcp_timer_active = 0;
00138   }
00139 }
00140 
00141 /**
00142  * Called from TCP_REG when registering a new PCB:
00143  * the reason is to have the TCP timer only running when
00144  * there are active (or time-wait) PCBs.
00145  */
00146 void
00147 tcp_timer_needed(void)
00148 {
00149   /* timer is off but needed again? */
00150   if (!tcpip_tcp_timer_active && (tcp_active_pcbs || tcp_tw_pcbs)) {
00151     /* enable and start timer */
00152     tcpip_tcp_timer_active = 1;
00153     sys_timeout(TCP_TMR_INTERVAL, tcpip_tcp_timer, NULL);
00154   }
00155 }
00156 #endif /* LWIP_TCP */
00157 
00158 /**
00159  * Timer callback function that calls mld6_tmr() and reschedules itself.
00160  *
00161  * @param arg unused argument
00162  */
00163 static void
00164 cyclic_timer(void *arg)
00165 {
00166   const struct lwip_cyclic_timer* cyclic = (const struct lwip_cyclic_timer*)arg;
00167 #if LWIP_DEBUG_TIMERNAMES
00168   LWIP_DEBUGF(TIMERS_DEBUG, ("tcpip: %s()\n", cyclic->handler_name));
00169 #endif
00170   cyclic->handler();
00171   sys_timeout(cyclic->interval_ms, cyclic_timer, arg);
00172 }
00173 
00174 /** Initialize this module */
00175 void sys_timeouts_init(void)
00176 {
00177   size_t i;
00178   /* tcp_tmr() at index 0 is started on demand */
00179   for (i = 1; i < LWIP_ARRAYSIZE(lwip_cyclic_timers); i++) {
00180     /* we have to cast via size_t to get rid of const warning
00181       (this is OK as cyclic_timer() casts back to const* */
00182     sys_timeout(lwip_cyclic_timers[i].interval_ms, cyclic_timer, (void*)(size_t)&lwip_cyclic_timers[i]);
00183   }
00184 
00185   /* Initialise timestamp for sys_check_timeouts */
00186   timeouts_last_time = sys_now();
00187 }
00188 
00189 /**
00190  * Create a one-shot timer (aka timeout). Timeouts are processed in the
00191  * following cases:
00192  * - while waiting for a message using sys_timeouts_mbox_fetch()
00193  * - by calling sys_check_timeouts() (NO_SYS==1 only)
00194  *
00195  * @param msecs time in milliseconds after that the timer should expire
00196  * @param handler callback function to call when msecs have elapsed
00197  * @param arg argument to pass to the callback function
00198  */
00199 #if LWIP_DEBUG_TIMERNAMES
00200 void
00201 sys_timeout_debug(u32_t msecs, sys_timeout_handler handler, void *arg, const char* handler_name)
00202 #else /* LWIP_DEBUG_TIMERNAMES */
00203 void
00204 sys_timeout(u32_t msecs, sys_timeout_handler handler, void *arg)
00205 #endif /* LWIP_DEBUG_TIMERNAMES */
00206 {
00207   struct sys_timeo *timeout, *t;
00208   u32_t now, diff;
00209 
00210   timeout = (struct sys_timeo *)memp_malloc(MEMP_SYS_TIMEOUT);
00211   if (timeout == NULL) {
00212     LWIP_ASSERT("sys_timeout: timeout != NULL, pool MEMP_SYS_TIMEOUT is empty", timeout != NULL);
00213     return;
00214   }
00215 
00216   now = sys_now();
00217   if (next_timeout == NULL) {
00218     diff = 0;
00219     timeouts_last_time = now;
00220   } else {
00221     diff = now - timeouts_last_time;
00222   }
00223 
00224   timeout->next = NULL;
00225   timeout->h = handler;
00226   timeout->arg = arg;
00227   timeout->time = msecs + diff;
00228 #if LWIP_DEBUG_TIMERNAMES
00229   timeout->handler_name = handler_name;
00230   LWIP_DEBUGF(TIMERS_DEBUG, ("sys_timeout: %p msecs=%"U32_F" handler=%s arg=%p\n",
00231     (void *)timeout, msecs, handler_name, (void *)arg));
00232 #endif /* LWIP_DEBUG_TIMERNAMES */
00233 
00234   if (next_timeout == NULL) {
00235     next_timeout = timeout;
00236     return;
00237   }
00238 
00239   if (next_timeout->time > msecs) {
00240     next_timeout->time -= msecs;
00241     timeout->next = next_timeout;
00242     next_timeout = timeout;
00243   } else {
00244     for (t = next_timeout; t != NULL; t = t->next) {
00245       timeout->time -= t->time;
00246       if (t->next == NULL || t->next->time > timeout->time) {
00247         if (t->next != NULL) {
00248           t->next->time -= timeout->time;
00249         } else if (timeout->time > msecs) {
00250           /* If this is the case, 'timeouts_last_time' and 'now' differs too much.
00251              This can be due to sys_check_timeouts() not being called at the right
00252              times, but also when stopping in a breakpoint. Anyway, let's assume
00253              this is not wanted, so add the first timer's time instead of 'diff' */
00254           timeout->time = msecs + next_timeout->time;
00255         }
00256         timeout->next = t->next;
00257         t->next = timeout;
00258         break;
00259       }
00260     }
00261   }
00262 }
00263 
00264 /**
00265  * Go through timeout list (for this task only) and remove the first matching
00266  * entry (subsequent entries remain untouched), even though the timeout has not
00267  * triggered yet.
00268  *
00269  * @param handler callback function that would be called by the timeout
00270  * @param arg callback argument that would be passed to handler
00271 */
00272 void
00273 sys_untimeout(sys_timeout_handler handler, void *arg)
00274 {
00275   struct sys_timeo *prev_t, *t;
00276 
00277   if (next_timeout == NULL) {
00278     return;
00279   }
00280 
00281   for (t = next_timeout, prev_t = NULL; t != NULL; prev_t = t, t = t->next) {
00282     if ((t->h == handler) && (t->arg == arg)) {
00283       /* We have a match */
00284       /* Unlink from previous in list */
00285       if (prev_t == NULL) {
00286         next_timeout = t->next;
00287       } else {
00288         prev_t->next = t->next;
00289       }
00290       /* If not the last one, add time of this one back to next */
00291       if (t->next != NULL) {
00292         t->next->time += t->time;
00293       }
00294       memp_free(MEMP_SYS_TIMEOUT, t);
00295       return;
00296     }
00297   }
00298   return;
00299 }
00300 
00301 /**
00302  * @ingroup lwip_nosys
00303  * Handle timeouts for NO_SYS==1 (i.e. without using
00304  * tcpip_thread/sys_timeouts_mbox_fetch(). Uses sys_now() to call timeout
00305  * handler functions when timeouts expire.
00306  *
00307  * Must be called periodically from your main loop.
00308  */
00309 #if !NO_SYS && !defined __DOXYGEN__
00310 static
00311 #endif /* !NO_SYS */
00312 void
00313 sys_check_timeouts(void)
00314 {
00315   if (next_timeout) {
00316     struct sys_timeo *tmptimeout;
00317     u32_t diff;
00318     sys_timeout_handler handler;
00319     void *arg;
00320     u8_t had_one;
00321     u32_t now;
00322 
00323     now = sys_now();
00324     /* this cares for wraparounds */
00325     diff = now - timeouts_last_time;
00326     do {
00327       PBUF_CHECK_FREE_OOSEQ();
00328       had_one = 0;
00329       tmptimeout = next_timeout;
00330       if (tmptimeout && (tmptimeout->time <= diff)) {
00331         /* timeout has expired */
00332         had_one = 1;
00333         timeouts_last_time += tmptimeout->time;
00334         diff -= tmptimeout->time;
00335         next_timeout = tmptimeout->next;
00336         handler = tmptimeout->h;
00337         arg = tmptimeout->arg;
00338 #if LWIP_DEBUG_TIMERNAMES
00339         if (handler != NULL) {
00340           LWIP_DEBUGF(TIMERS_DEBUG, ("sct calling h=%s arg=%p\n",
00341             tmptimeout->handler_name, arg));
00342         }
00343 #endif /* LWIP_DEBUG_TIMERNAMES */
00344         memp_free(MEMP_SYS_TIMEOUT, tmptimeout);
00345         if (handler != NULL) {
00346 #if !NO_SYS
00347           /* For LWIP_TCPIP_CORE_LOCKING, lock the core before calling the
00348              timeout handler function. */
00349           LOCK_TCPIP_CORE();
00350 #endif /* !NO_SYS */
00351           handler(arg);
00352 #if !NO_SYS
00353           UNLOCK_TCPIP_CORE();
00354 #endif /* !NO_SYS */
00355         }
00356         LWIP_TCPIP_THREAD_ALIVE();
00357       }
00358     /* repeat until all expired timers have been called */
00359     } while (had_one);
00360   }
00361 }
00362 
00363 #if NO_SYS
00364 /** Set back the timestamp of the last call to sys_check_timeouts()
00365  * This is necessary if sys_check_timeouts() hasn't been called for a long
00366  * time (e.g. while saving energy) to prevent all timer functions of that
00367  * period being called.
00368  */
00369 void
00370 sys_restart_timeouts(void)
00371 {
00372   timeouts_last_time = sys_now();
00373 }
00374 #endif /* NO_SYS */
00375 
00376 /** Return the time left before the next timeout is due. If no timeouts are
00377  * enqueued, returns 0xffffffff
00378  */
00379 #if !NO_SYS
00380 static
00381 #endif /* !NO_SYS */
00382 u32_t
00383 sys_timeouts_sleeptime(void)
00384 {
00385   u32_t diff;
00386   if (next_timeout == NULL) {
00387     return 0xffffffff;
00388   }
00389   diff = sys_now() - timeouts_last_time;
00390   if (diff > next_timeout->time) {
00391     return 0;
00392   } else {
00393     return next_timeout->time - diff;
00394   }
00395 }
00396 
00397 #if !NO_SYS
00398 
00399 /**
00400  * Wait (forever) for a message to arrive in an mbox.
00401  * While waiting, timeouts are processed.
00402  *
00403  * @param mbox the mbox to fetch the message from
00404  * @param msg the place to store the message
00405  */
00406 void
00407 sys_timeouts_mbox_fetch(sys_mbox_t *mbox, void **msg)
00408 {
00409   u32_t sleeptime;
00410 
00411 again:
00412   if (!next_timeout) {
00413     sys_arch_mbox_fetch(mbox, msg, 0);
00414     return;
00415   }
00416 
00417   sleeptime = sys_timeouts_sleeptime();
00418   if (sleeptime == 0 || sys_arch_mbox_fetch(mbox, msg, sleeptime) == SYS_ARCH_TIMEOUT) {
00419     /* If a SYS_ARCH_TIMEOUT value is returned, a timeout occurred
00420        before a message could be fetched. */
00421     sys_check_timeouts();
00422     /* We try again to fetch a message from the mbox. */
00423     goto again;
00424   }
00425 }
00426 
00427 #endif /* NO_SYS */
00428 
00429 #else /* LWIP_TIMERS && !LWIP_TIMERS_CUSTOM */
00430 /* Satisfy the TCP code which calls this function */
00431 void
00432 tcp_timer_needed(void)
00433 {
00434 }
00435 #endif /* LWIP_TIMERS && !LWIP_TIMERS_CUSTOM */