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 0.6.1
===== =====
20-Dec-2007: - DNS failure cache: do several attempts before blacklisting
28-Nov-2007: - Fix: Detach from controlling TTY if daemonized 28-Nov-2007: - Fix: Detach from controlling TTY if daemonized
22-Nov-2007: - Working on code that that will allow siproxd to use 22-Nov-2007: - Working on code that that will allow siproxd to use
separate interfaces in its "in front of NAT routes" setup. 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 URL_STRING_SIZE 128 /* max size of an URL/URI string */
#define STATUSCODE_SIZE 5 /* size of string representation of status */ #define STATUSCODE_SIZE 5 /* size of string representation of status */
#define DNS_CACHE_SIZE 256 /* number of entries in internal DNS cache */ #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_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 DNS_BAD_AGE 600 /* maximum age of a bad cache entry (sec) */
#define IFADR_CACHE_SIZE 32 /* number of entries in internal IFADR cache */ #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 * STS_FAILURE on failure
*/ */
int get_ip_by_host(char *hostname, struct in_addr *addr) { int get_ip_by_host(char *hostname, struct in_addr *addr) {
int i, j, k; int i, j, k, idx;
time_t t1, t2; time_t t1, t2;
struct hostent *hostentry; struct hostent *hostentry;
#if defined(HAVE_GETHOSTBYNAME_R) #if defined(HAVE_GETHOSTBYNAME_R)
@ -74,6 +74,7 @@ int get_ip_by_host(char *hostname, struct in_addr *addr) {
static struct { static struct {
time_t expires_timestamp; /* time of expiration */ time_t expires_timestamp; /* time of expiration */
struct in_addr addr; /* IP address or 0.0.0.0 if a bad entry */ 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 bad_entry; /* != 0 if resolving failed */
char hostname[HOSTNAME_SIZE+1]; char hostname[HOSTNAME_SIZE+1];
} dns_cache[DNS_CACHE_SIZE]; } 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 * search requested entry in cache
*/ */
idx=0;
for (i=0; i<DNS_CACHE_SIZE; i++) { for (i=0; i<DNS_CACHE_SIZE; i++) {
if (dns_cache[i].hostname[0]=='\0') continue; /* empty */ if (dns_cache[i].hostname[0]=='\0') continue; /* empty */
if (strcasecmp(hostname, dns_cache[i].hostname) == 0) { /* match */ if (strcasecmp(hostname, dns_cache[i].hostname) == 0) { /* match */
memcpy(addr, &dns_cache[i].addr, sizeof(struct in_addr)); memcpy(addr, &dns_cache[i].addr, sizeof(struct in_addr));
if (dns_cache[i].bad_entry) { 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); hostname);
return STS_FAILURE; 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", DEBUGC(DBCLASS_DNS, "DNS lookup - from cache: %s -> %s",
hostname, utils_inet_ntoa(*addr)); hostname, utils_inet_ntoa(*addr));
return STS_SUCCESS; return STS_SUCCESS;
@ -203,47 +211,59 @@ int get_ip_by_host(char *hostname, struct in_addr *addr) {
hostname, utils_inet_ntoa(*addr)); hostname, utils_inet_ntoa(*addr));
} }
/* /* if we already have the entry, skip finding a new empty one */
* find an empty slot in the cache if (idx == 0) {
*/ /*
j=0; * find an empty slot in the cache
k=0; */
t1=INT_MAX; j=0;
t2=INT_MAX; k=0;
for (i=0; i<DNS_CACHE_SIZE; i++) { t1=INT_MAX;
if (dns_cache[i].hostname[0]=='\0') break; t2=INT_MAX;
if ((dns_cache[i].expires_timestamp < t1) && for (i=0; i<DNS_CACHE_SIZE; i++) {
(dns_cache[i].bad_entry == 0)) { if (dns_cache[i].hostname[0]=='\0') break;
/* remember oldest good entry */ if ((dns_cache[i].expires_timestamp < t1) &&
t1=dns_cache[i].expires_timestamp; (dns_cache[i].bad_entry == 0)) {
j=i; /* remember oldest good entry */
} else t1=dns_cache[i].expires_timestamp;
if (dns_cache[i].expires_timestamp < t2) { j=i;
/* remember oldest bad entry */ } else
t2=dns_cache[i].expires_timestamp; if (dns_cache[i].expires_timestamp < t2) {
k=i; /* remember oldest bad entry */
t2=dns_cache[i].expires_timestamp;
k=i;
}
} }
} /* if no empty slot found, victimize oldest one.
/* if no empty slot found, victimize oldest one. * Give preference to the oldest "bad" entry if
* Give preference to the oldest "bad" entry if * one exists */
* one exists */ if (i >= DNS_CACHE_SIZE) {
if (i >= DNS_CACHE_SIZE) { if (k > 0) i=k;
if (k > 0) i=k; else i=j;
else i=j; }
idx=i;
memset(&dns_cache[idx], 0, sizeof(dns_cache[0]));
} }
/* /*
* store the result in the cache * store the result in the cache
*/ */
DEBUGC(DBCLASS_DNS, "DNS lookup - store into cache, entry %i)", i); DEBUGC(DBCLASS_DNS, "DNS lookup - store into cache, entry %i)", idx);
memset(&dns_cache[i], 0, sizeof(dns_cache[0])); strncpy(dns_cache[idx].hostname, hostname, HOSTNAME_SIZE);
strncpy(dns_cache[i].hostname, hostname, HOSTNAME_SIZE); dns_cache[idx].expires_timestamp = time(NULL) + DNS_GOOD_AGE;
if (hostentry) { if (hostentry) {
dns_cache[i].expires_timestamp = time(NULL) + DNS_GOOD_AGE; memcpy(&dns_cache[idx].addr, addr, sizeof(struct in_addr));
memcpy(&dns_cache[i].addr, addr, sizeof(struct in_addr)); dns_cache[idx].error_count = 0;
dns_cache[idx].bad_entry = 0;
} else { } else {
dns_cache[i].expires_timestamp = time(NULL) + DNS_BAD_AGE; dns_cache[idx].error_count++;
dns_cache[i].bad_entry = 1; 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; return STS_SUCCESS;
} }