Added a more fine grained locking system for multiple threads.
Removed the new_dnscache() function and moved it into dnscache(). Fixed a memory leak in dns_insert().
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@ -1,4 +1,4 @@
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/* $Id: dnscache.c,v 1.9 2001-05-27 02:24:00 rjkaes Exp $
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/* $Id: dnscache.c,v 1.10 2001-08-29 03:57:51 rjkaes Exp $
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*
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* This is a caching DNS system. When a host name is needed we look it up here
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* and see if there is already an answer for it. The domains are placed in a
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@ -34,6 +34,14 @@
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#include "ternary.h"
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#include "utils.h"
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/*
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* The mutex is used for locking around accesses to the ternary tree.
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*/
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static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
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#define LOCK() pthread_mutex_lock(&mutex);
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#define UNLOCK() pthread_mutex_unlock(&mutex);
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#define DNSEXPIRE (5 * 60)
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struct dnscache_s {
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@ -41,49 +49,94 @@ struct dnscache_s {
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time_t expire;
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};
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static TERNARY dns_tree;
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static TERNARY dns_tree = -1;
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TERNARY new_dnscache(void)
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/*
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* Insert the data into the DNS tree.
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*/
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static int insert_data(char *domain, struct dnscache_s *newptr)
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{
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dns_tree = ternary_new();
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int ret;
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LOCK();
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ret = ternary_insert(dns_tree, domain, newptr);
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UNLOCK();
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return dns_tree;
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return ret;
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}
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static int dns_lookup(struct in_addr *addr, char *domain)
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{
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int ret;
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struct dnscache_s *ptr;
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assert(addr != NULL);
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assert(domain != NULL);
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if (TE_ISERROR(ternary_search(dns_tree, domain, (void *)&ptr)))
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return -1;
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LOCK();
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ret = ternary_search(dns_tree, domain, (void *)&ptr);
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if (difftime(time(NULL), ptr->expire) > (double)DNSEXPIRE) {
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if (TE_ISERROR(ret)
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|| difftime(time(NULL), ptr->expire) > DNSEXPIRE) {
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UNLOCK();
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return -1;
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}
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*addr = ptr->ipaddr;
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memcpy(addr, &ptr->ipaddr, sizeof(struct in_addr));
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UNLOCK();
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return 0;
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}
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static int dns_insert(struct in_addr *addr, char *domain)
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{
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struct dnscache_s *newptr;
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int ret;
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assert(addr != NULL);
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assert(domain != NULL);
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DEBUG2("Inserting [%s] into DNS cache", domain);
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if (!(newptr = malloc(sizeof(struct dnscache_s)))) {
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return -1;
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}
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newptr->ipaddr = *addr;
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memcpy(&newptr->ipaddr, addr, sizeof(struct in_addr));
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newptr->expire = time(NULL);
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if (TE_ISERROR(ternary_insert(dns_tree, domain, newptr)))
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safefree(newptr);
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ret = insert_data(domain, newptr);
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if (TE_ISERROR(ret)) {
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if (ret == TE_EXISTS) {
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/*
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* The value already exists. First search for the
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* value and then delete the data before inserting
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* the new value.
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*/
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struct dnscache_s *existing;
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DEBUG2("[%s] already exists in DNS cache", domain);
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LOCK();
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ret = ternary_search(dns_tree, domain, (void *)&existing);
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UNLOCK();
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if (TE_ISERROR(ret))
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goto INSERT_ERROR;
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safefree(existing);
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ret = insert_data(domain, newptr);
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if (TE_ISERROR(ret))
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goto INSERT_ERROR;
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} else {
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INSERT_ERROR:
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safefree(newptr);
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return -1;
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}
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}
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return 0;
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}
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@ -95,7 +148,13 @@ int dnscache(struct in_addr *addr, char *domain)
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assert(addr != NULL);
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assert(domain != NULL);
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if (inet_aton(domain, (struct in_addr *) addr) != 0)
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/* If the DNS tree doesn't exist, build a new one */
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LOCK();
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if (dns_tree < 0)
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dns_tree = ternary_new();
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UNLOCK();
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if (inet_aton(domain, (struct in_addr *)addr) != 0)
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return 0;
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/* Well, we're not dotted-decimal so we need to look it up */
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@ -103,10 +162,15 @@ int dnscache(struct in_addr *addr, char *domain)
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return 0;
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/* Okay, so not in the list... need to actually look it up. */
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if (!(resolv = gethostbyname(domain)))
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LOCK();
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if (!(resolv = gethostbyname(domain))) {
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UNLOCK();
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return -1;
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}
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memcpy(addr, resolv->h_addr_list[0], (size_t)resolv->h_length);
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UNLOCK();
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dns_insert(addr, domain);
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return 0;
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