DeforaNetworks/siproxd
DeforaNetworks/siproxd
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- DNS failure cache: do several attempts before blacklisting

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This commit is contained in:
Thomas Ries 2007-12-20 17:42:10 +00:00
parent 6859b0b9b3
commit f81e32fe73
3 changed files with 58 additions and 35 deletions
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1
ChangeLog
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@ -1,5 +1,6 @@
0.6.1
=====
20-Dec-2007: - DNS failure cache: do several attempts before blacklisting
28-Nov-2007: - Fix: Detach from controlling TTY if daemonized
22-Nov-2007: - Working on code that that will allow siproxd to use
separate interfaces in its "in front of NAT routes" setup.

2
src/siproxd.h
View File

@ -261,6 +261,8 @@ int sip_message_set_body(osip_message_t * sip, const char *buf, size_t len);
#define URL_STRING_SIZE 128 /* max size of an URL/URI string */
#define STATUSCODE_SIZE 5 /* size of string representation of status */
#define DNS_CACHE_SIZE 256 /* number of entries in internal DNS cache */
#define DNS_ATTEMPTS 3 /* number of attempts to resolve a name
before it is marked as bad */
#define DNS_GOOD_AGE 60 /* maximum age of a good cache entry (sec) */
#define DNS_BAD_AGE 600 /* maximum age of a bad cache entry (sec) */
#define IFADR_CACHE_SIZE 32 /* number of entries in internal IFADR cache */

90
src/utils.c
View File

@ -63,7 +63,7 @@ extern int h_errno;
* STS_FAILURE on failure
*/
int get_ip_by_host(char *hostname, struct in_addr *addr) {
int i, j, k;
int i, j, k, idx;
time_t t1, t2;
struct hostent *hostentry;
#if defined(HAVE_GETHOSTBYNAME_R)
@ -74,6 +74,7 @@ int get_ip_by_host(char *hostname, struct in_addr *addr) {
static struct {
time_t expires_timestamp; /* time of expiration */
struct in_addr addr; /* IP address or 0.0.0.0 if a bad entry */
char error_count; /* counts failed resolution attempts */
char bad_entry; /* != 0 if resolving failed */
char hostname[HOSTNAME_SIZE+1];
} dns_cache[DNS_CACHE_SIZE];
@ -109,15 +110,22 @@ int get_ip_by_host(char *hostname, struct in_addr *addr) {
/*
* search requested entry in cache
*/
idx=0;
for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') continue; /* empty */
if (strcasecmp(hostname, dns_cache[i].hostname) == 0) { /* match */
memcpy(addr, &dns_cache[i].addr, sizeof(struct in_addr));
if (dns_cache[i].bad_entry) {
DEBUGC(DBCLASS_DNS, "DNS lookup - bad entry from cache: %s",
DEBUGC(DBCLASS_DNS, "DNS lookup - blacklisted from cache: %s",
hostname);
return STS_FAILURE;
}
if (dns_cache[i].error_count > 0) {
DEBUGC(DBCLASS_DNS, "DNS lookup - previous resolution failed: %s"
", attempt %i", hostname, dns_cache[i].error_count);
idx=i;
break;
}
DEBUGC(DBCLASS_DNS, "DNS lookup - from cache: %s -> %s",
hostname, utils_inet_ntoa(*addr));
return STS_SUCCESS;
@ -203,47 +211,59 @@ int get_ip_by_host(char *hostname, struct in_addr *addr) {
hostname, utils_inet_ntoa(*addr));
}
/*
* find an empty slot in the cache
*/
j=0;
k=0;
t1=INT_MAX;
t2=INT_MAX;
for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') break;
if ((dns_cache[i].expires_timestamp < t1) &&
(dns_cache[i].bad_entry == 0)) {
/* remember oldest good entry */
t1=dns_cache[i].expires_timestamp;
j=i;
} else
if (dns_cache[i].expires_timestamp < t2) {
/* remember oldest bad entry */
t2=dns_cache[i].expires_timestamp;
k=i;
/* if we already have the entry, skip finding a new empty one */
if (idx == 0) {
/*
* find an empty slot in the cache
*/
j=0;
k=0;
t1=INT_MAX;
t2=INT_MAX;
for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') break;
if ((dns_cache[i].expires_timestamp < t1) &&
(dns_cache[i].bad_entry == 0)) {
/* remember oldest good entry */
t1=dns_cache[i].expires_timestamp;
j=i;
} else
if (dns_cache[i].expires_timestamp < t2) {
/* remember oldest bad entry */
t2=dns_cache[i].expires_timestamp;
k=i;
}
}
}
/* if no empty slot found, victimize oldest one.
* Give preference to the oldest "bad" entry if
* one exists */
if (i >= DNS_CACHE_SIZE) {
if (k > 0) i=k;
else i=j;
/* if no empty slot found, victimize oldest one.
* Give preference to the oldest "bad" entry if
* one exists */
if (i >= DNS_CACHE_SIZE) {
if (k > 0) i=k;
else i=j;
}
idx=i;
memset(&dns_cache[idx], 0, sizeof(dns_cache[0]));
}
/*
* store the result in the cache
*/
DEBUGC(DBCLASS_DNS, "DNS lookup - store into cache, entry %i)", i);
memset(&dns_cache[i], 0, sizeof(dns_cache[0]));
strncpy(dns_cache[i].hostname, hostname, HOSTNAME_SIZE);
DEBUGC(DBCLASS_DNS, "DNS lookup - store into cache, entry %i)", idx);
strncpy(dns_cache[idx].hostname, hostname, HOSTNAME_SIZE);
dns_cache[idx].expires_timestamp = time(NULL) + DNS_GOOD_AGE;
if (hostentry) {
dns_cache[i].expires_timestamp = time(NULL) + DNS_GOOD_AGE;
memcpy(&dns_cache[i].addr, addr, sizeof(struct in_addr));
memcpy(&dns_cache[idx].addr, addr, sizeof(struct in_addr));
dns_cache[idx].error_count = 0;
dns_cache[idx].bad_entry = 0;
} else {
dns_cache[i].expires_timestamp = time(NULL) + DNS_BAD_AGE;
dns_cache[i].bad_entry = 1;
dns_cache[idx].error_count++;
DEBUGC(DBCLASS_DNS, "DNS lookup - errcnt=%i", dns_cache[idx].error_count);
if (dns_cache[idx].error_count >= DNS_ATTEMPTS) {
DEBUGC(DBCLASS_DNS, "DNS lookup - blacklisting entry");
dns_cache[idx].expires_timestamp = time(NULL) + DNS_BAD_AGE;
dns_cache[idx].bad_entry = 1;
}
return STS_FAILURE;
}
return STS_SUCCESS;
}