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Up to now the DNS resolver relied on the uIP 1/2 second polling for its retry management (implementing a linear back-off). But Contiki 2.x uIP doesn't implement the 1/2 second polling for UDP connections anymore! Therefore I added an event timer to the DNS resolver for its retry management. I went for a 1 second interval (still with the same linear back-off) as compromise between officially recommended longer intervals (i.e. BIND with 5 seconds and exponential back-off) and a reasonable user experience for the self induced packet loss in ARP setups.

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oliverschmidt 2007-01-07 13:52:25 +00:00
parent 7993f46e76
commit cada8d324f
1 changed files with 10 additions and 4 deletions
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14
core/net/resolv.c
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@ -57,7 +57,7 @@
* *
* This file is part of the uIP TCP/IP stack. * This file is part of the uIP TCP/IP stack.
* *
* $Id: resolv.c,v 1.4 2006/09/18 23:30:40 oliverschmidt Exp $ * $Id: resolv.c,v 1.5 2007/01/07 13:52:25 oliverschmidt Exp $
* *
*/ */
@ -133,6 +133,8 @@ static u8_t seqno;
static struct uip_udp_conn *resolv_conn = NULL; static struct uip_udp_conn *resolv_conn = NULL;
static struct etimer retry;
process_event_t resolv_event_found; process_event_t resolv_event_found;
PROCESS(resolv_process, "DNS resolver"); PROCESS(resolv_process, "DNS resolver");
@ -185,6 +187,7 @@ check_entries(void)
namemapptr = &names[i]; namemapptr = &names[i];
if(namemapptr->state == STATE_NEW || if(namemapptr->state == STATE_NEW ||
namemapptr->state == STATE_ASKING) { namemapptr->state == STATE_ASKING) {
etimer_set(&retry, CLOCK_SECOND);
if(namemapptr->state == STATE_ASKING) { if(namemapptr->state == STATE_ASKING) {
if(--namemapptr->tmr == 0) { if(--namemapptr->tmr == 0) {
if(++namemapptr->retries == MAX_RETRIES) { if(++namemapptr->retries == MAX_RETRIES) {
@ -328,7 +331,6 @@ newdata(void)
--nanswers; --nanswers;
} }
} }
} }
/*-----------------------------------------------------------------------------------*/ /*-----------------------------------------------------------------------------------*/
/** \internal /** \internal
@ -351,11 +353,15 @@ PROCESS_THREAD(resolv_process, ev, data)
while(1) { while(1) {
PROCESS_WAIT_EVENT(); PROCESS_WAIT_EVENT();
if(ev == EVENT_NEW_SERVER) { if(ev == PROCESS_EVENT_TIMER) {
if(resolv_conn != NULL) {
tcpip_poll_udp(resolv_conn);
}
} else if(ev == EVENT_NEW_SERVER) {
if(resolv_conn != NULL) { if(resolv_conn != NULL) {
uip_udp_remove(resolv_conn); uip_udp_remove(resolv_conn);
} }
resolv_conn = udp_new((uip_ipaddr_t *)data, HTONS(53), NULL); resolv_conn = udp_new((uip_ipaddr_t *)data, HTONS(53), NULL);
} else if(ev == tcpip_event) { } else if(ev == tcpip_event) {