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Fix DNS client TTL processing.

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This commit is contained in:
fbernon 2007-11-18 21:30:45 +00:00
parent 7f0640b040
commit da4df1f414
2 changed files with 21 additions and 19 deletions
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27
src/core/dns.c
View File

@ -106,11 +106,6 @@
#define DNS_MAX_RETRIES 4
#endif
/* DNS entry time to live (in DNS_TMR_INTERVAL ticks) */
#ifndef DNS_TTL_ENTRY
#define DNS_TTL_ENTRY 60
#endif
/* DNS protocol flags */
#define DNS_FLAG1_RESPONSE 0x80
#define DNS_FLAG1_OPCODE_STATUS 0x10
@ -189,13 +184,13 @@ PACK_STRUCT_END
PACK_STRUCT_BEGIN
/** DNS table entry */
struct dns_table_entry {
u8_t state;
u8_t numdns;
u8_t tmr;
u8_t retries;
u8_t ttl;
u8_t seqno;
u8_t err;
u8_t state;
u8_t numdns;
u8_t tmr;
u8_t retries;
u8_t seqno;
u8_t err;
u32_t ttl;
char name[DNS_MAX_NAME_LENGTH];
struct ip_addr ipaddr;
void (* found)(const char *name, struct ip_addr *ipaddr, void *arg); /* pointer to callback on DNS query done */
@ -518,7 +513,6 @@ dns_recv(void *s, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16
if(pEntry->state == DNS_STATE_ASKING) {
/* This entry is now completed. */
pEntry->state = DNS_STATE_DONE;
pEntry->ttl = DNS_TTL_ENTRY;
pEntry->err = hdr->flags2 & DNS_FLAG2_ERR_MASK;
/* We only care about the question(s) and the answers. The authrr
@ -527,7 +521,7 @@ dns_recv(void *s, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16
nanswers = htons(hdr->numanswers);
/* Check for error. If so, call callback to inform. */
if (((hdr->flags1 & DNS_FLAG1_RESPONSE)==0) ||(pEntry->err != 0) || (nquestions != 1)) {
if (((hdr->flags1 & DNS_FLAG1_RESPONSE)==0) || (pEntry->err != 0) || (nquestions != 1)) {
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": error in flags\n", pEntry->name));
/* call specified callback function if provided */
if (pEntry->found)
@ -551,6 +545,11 @@ dns_recv(void *s, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16
/* Check for IP address type and Internet class. Others are discarded. */
ans = (struct dns_answer *)pHostname;
if((ntohs(ans->type) == DNS_RRTYPE_A) && (ntohs(ans->class) == DNS_RRCLASS_IN) && (ntohs(ans->len) == sizeof(struct ip_addr)) ) {
/* read the answer resource record's TTL, and maximize it if needed */
pEntry->ttl = ntohl(ans->ttl);
if (pEntry->ttl > DNS_MAX_TTL) {
pEntry->ttl = DNS_MAX_TTL;
}
/* read the IP address after answer resource record's header */
pEntry->ipaddr = (*((struct ip_addr*)(ans+1)));
LWIP_DEBUGF(DNS_DEBUG, ("dns_recv: \"%s\": response = ", pEntry->name));

13
src/include/lwip/dns.h
View File

@ -38,16 +38,19 @@
#if LWIP_DNS /* don't build if not configured for use in lwipopts.h */
/** DNS timer period */
#ifndef DNS_TMR_INTERVAL
#define DNS_TMR_INTERVAL 1000
#endif
/** The maximum of DNS servers */
#ifndef DNS_MAX_SERVERS
#define DNS_MAX_SERVERS 2
#endif
/** DNS resource record max. TTL (one week as default) */
#ifndef DNS_MAX_TTL
#define DNS_MAX_TTL 604800
#endif
/** DNS timer period */
#define DNS_TMR_INTERVAL 1000
/** DNS message max. size */
#define DNS_MSG_SIZE 512