Re: pkg/36853: clamav-milter doesn't start - _res is not supported for multi-threaded programs.

[christos%zoulas.com@localhost (Christos Zoulas)]

On Dec 21, 11:30am, carl%bl.echidna.id.au@localhost (Carl Brewer) wrote:
-- Subject: Re: pkg/36853: clamav-milter doesn't start - _res is not supporte

Here is an *UNTESTED* patch that fixes the race in res_query for non-bind9
systems, and uses res_ninit/res_nquery in bind9 systems.

Enjoy,

christos

--- clamav-milter.c.orig        2007-12-12 17:41:25.000000000 -0500
+++ clamav-milter.c     2007-12-21 11:47:01.000000000 -0500
@@ -90,6 +90,9 @@
 #if    HAVE_RESOLV_H
 #include <arpa/nameser.h>      /* for HEADER */
 #include <resolv.h>
+#if __RES >= 20030124
+#define        HAVE_BIND9
+#endif
 #endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
@@ -505,6 +508,20 @@
 #endif /*SESSION*/
 
 static pthread_cond_t  watchdog_cond = PTHREAD_COND_INITIALIZER;
+#ifndef HAVE_BIND9
+static pthread_mutex_t res_mutex = PTHREAD_MUTEX_INITIALIZER;
+#define RES_QUERY(len, h, c, t, q, s) \
+       do { \
+               pthread_mutex_lock(&res_mutex); \
+               len = res_query((h), (c), (t), (q), (s)); \
+               pthread_mutex_unlock(&res_mutex); \
+       } while (/*CONSTCOND*/0)
+#else
+static pthread_key_t res_key;
+#define RES_QUERY(len, h, c, t, q, s) \
+       len = res_nquery((res_state)pthread_getspecific(res_key), \
+           (h), (c), (t), (q), (s))
+#endif
 
 #ifndef        SHUT_RD
 #define        SHUT_RD         0
@@ -2061,12 +2078,19 @@
        logg(_("Starting %s\n"), clamav_version);
        logg(_("*Debugging is on\n"));
 
+#ifndef HAVE_BIND9
        if(!(_res.options&RES_INIT))
                if(res_init() < 0) {
                        fprintf(stderr, "%s: Can't initialise the resolver\n",
                                argv[0]);
                        return EX_UNAVAILABLE;
                }
+#else
+       if (pthread_key_create(&res_key, free)) {
+               perror("pthread_key_create");
+               return EX_UNAVAILABLE;
+       }
+#endif
 
        if(blacklist_time) {
                char name[MAXHOSTNAMELEN + 1];
@@ -2579,6 +2603,18 @@
        int sock = s->sock;
        struct sockaddr *server = (struct sockaddr *)s->server;
        int server_index = s->server_index;
+#ifdef HAVE_BIND9
+       res_state res = cli_calloc(1, sizeof(*res));
+       if (pthread_setspecific(res_key, res)) {
+               perror("pthread_setspecific");
+               free(res);
+               return NULL;
+       }
+       if (res_ninit(res) < 0) {
+               perror("res_ninit");
+               return NULL;
+       }
+#endif
 
        if(last_failed_pings[server_index]) {
                s->rc = 0;
@@ -6150,7 +6186,7 @@
                        return NULL;
        }
 
-       len = res_query(host, C_IN, T_MX, (u_char *)&q, sizeof(q));
+       RES_QUERY(len, host, C_IN, T_MX, (u_char *)&q, sizeof(q));
        if(len < 0)
                return t;       /* Host has no MX records */
 
@@ -6219,7 +6255,7 @@
        if((host == NULL) || (*host == '\0'))
                return t;
 
-       len = res_query(host, C_IN, T_A, (u_char *)&q, sizeof(q));
+       RES_QUERY(len, host, C_IN, T_A, (u_char *)&q, sizeof(q));
        if(len < 0)
                return t;       /* Host has no A records */
 
@@ -6278,7 +6314,6 @@
  *     an SPF system, we ONLY use SPF records to reduce phish false positives
  * TODO: IPv6?
  * TODO: cache queries?
- * TODO: check res_query is thread safe
  *
  * INPUT: prevhosts, a list of hosts already searched: stops include loops
  *     e.g. mercado.com includes medrcadosw.com which includes mercado.com,
@@ -6330,7 +6365,7 @@
                *ptr = '\0';
 
        logg("*SPF query '%s'\n", host);
-       len = res_query(host, C_IN, T_TXT, (u_char *)&q, sizeof(q));
+       RES_QUERY(len, host, C_IN, T_TXT, (u_char *)&q, sizeof(q));
        if(len < 0) {
                free(host);
                return 0;       /* Host has no TXT records */