MINOR: dns: Cache previous DNS answers.
As DNS servers may not return all IPs in one answer, we want to cache the
previous entries. Those entries are removed when considered obsolete, which
happens when the IP hasn't been returned by the DNS server for a time
defined in the "hold obsolete" parameter of the resolver section. The default
is 30s.
diff --git a/include/types/dns.h b/include/types/dns.h
index 7a19aa3..12c1155 100644
--- a/include/types/dns.h
+++ b/include/types/dns.h
@@ -113,7 +113,7 @@
/* NOTE: big endian structure */
struct dns_answer_item {
struct list list;
- char *name; /* answer name
+ char name[DNS_MAX_NAME_SIZE]; /* answer name
* For SRV type, name also includes service
* and protocol value */
int16_t type; /* question type */
@@ -124,7 +124,8 @@
int16_t port; /* SRV type port */
int16_t data_len; /* number of bytes in target below */
struct sockaddr address; /* IPv4 or IPv6, network format */
- char *target; /* Response data: SRV or CNAME type target */
+ char target[DNS_MAX_NAME_SIZE]; /* Response data: SRV or CNAME type target */
+ time_t last_seen; /* When was the answer was last seen */
};
struct dns_response_packet {
@@ -158,6 +159,7 @@
int timeout; /* no answer was delivered */
int refused; /* dns server refused to answer */
int other; /* other dns response errors */
+ int obsolete; /* an answer hasn't been seen */
} hold;
struct task *t; /* timeout management */
int resolution_pool_size; /* size of the resolution pool associated to this resolvers section */
@@ -252,8 +254,6 @@
unsigned long long revision; /* updated for each update */
struct dns_response_packet response; /* structure hosting the DNS response */
struct dns_query_item response_query_records[DNS_MAX_QUERY_RECORDS]; /* <response> query records */
- struct dns_answer_item response_answer_records[DNS_MAX_ANSWER_RECORDS]; /* <response> answer records */
- struct chunk response_buffer; /* buffer used as a data store for <response> above TODO: optimize the size (might be smaller) */
};
/*
@@ -315,6 +315,7 @@
DNS_UPD_CNAME, /* CNAME without any IP provided in the response */
DNS_UPD_NAME_ERROR, /* name in the response did not match the query */
DNS_UPD_NO_IP_FOUND, /* no IP could be found in the response */
+ DNS_UPD_OBSOLETE_IP, /* The server IP was obsolete, and no other IP was found */
};
#endif /* _TYPES_DNS_H */