Fix bug #78008: dns_check_record() always return true on Alpine

- free handle before return result
- cleaned up remaining usage of MAXPACKET
- update dns_get_mx() to use the same approach

Closes GH-5854.

diff --git a/NEWS b/NEWS
index b230a84c5c6b1c600d7931a81fab00e546d15262..0aa1b695b575affa0d60f10d74f3cbd3721d1cd6 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -31,6 +31,8 @@ PHP                                                                        NEWS
 - Standard:
   . Fixed bug #70362 (Can't copy() large 'data://' with open_basedir). (cmb)
   . Fixed bug #79817 (str_replace() does not handle INDIRECT elements). (Nikita)
+  . Fixed bug #78008 (dns_check_record() always return true on Alpine).
+    (Andy Postnikov)
 
 ?? ??? ????, PHP 7.3.20
 

diff --git a/ext/standard/dns.c b/ext/standard/dns.c
index 4ee40aa5ec4dfebaf0b4703960471a678f876af6..705c8e4fad278ec4b1c2f577b23457c4110facfb 100644 (file)
--- a/ext/standard/dns.c
+++ b/ext/standard/dns.c
@@ -349,10 +349,8 @@ static void _php_dns_free_res(struct __res_state *res) { /* {{{ */
    Check DNS records corresponding to a given Internet host name or IP address */
 PHP_FUNCTION(dns_check_record)
 {
-#ifndef MAXPACKET
-#define MAXPACKET  8192 /* max packet size used internally by BIND */
-#endif
-       u_char ans[MAXPACKET];
+       HEADER *hp;
+       querybuf answer;
        char *hostname, *rectype = NULL;
        size_t hostname_len, rectype_len = 0;
        int type = T_MX, i;
@@ -410,14 +408,14 @@ PHP_FUNCTION(dns_check_record)
        res_init();
 #endif
 
-       RETVAL_TRUE;
-       i = php_dns_search(handle, hostname, C_IN, type, ans, sizeof(ans));
+       i = php_dns_search(handle, hostname, C_IN, type, answer.qb2, sizeof answer);
+       php_dns_free_handle(handle);
 
        if (i < 0) {
-               RETVAL_FALSE;
+               RETURN_FALSE;
        }
-
-       php_dns_free_handle(handle);
+       hp = (HEADER *)&answer;
+       RETURN_BOOL(ntohs(hp->ancount) != 0);
 }
 /* }}} */
 
@@ -1033,7 +1031,7 @@ PHP_FUNCTION(dns_get_mx)
        zval *mx_list, *weight_list = NULL;
        int count, qdc;
        u_short type, weight;
-       u_char ans[MAXPACKET];
+       querybuf answer;
        char buf[MAXHOSTNAMELEN];
        HEADER *hp;
        u_char *cp, *end;
@@ -1076,16 +1074,14 @@ PHP_FUNCTION(dns_get_mx)
        res_init();
 #endif
 
-       i = php_dns_search(handle, hostname, C_IN, DNS_T_MX, (u_char *)&ans, sizeof(ans));
+       i = php_dns_search(handle, hostname, C_IN, DNS_T_MX, answer.qb2, sizeof answer);
        if (i < 0) {
+               php_dns_free_handle(handle);
                RETURN_FALSE;
        }
-       if (i > (int)sizeof(ans)) {
-               i = sizeof(ans);
-       }
-       hp = (HEADER *)&ans;
-       cp = (u_char *)&ans + HFIXEDSZ;
-       end = (u_char *)&ans +i;
+       hp = (HEADER *)&answer;
+       cp = answer.qb2 + HFIXEDSZ;
+       end = answer.qb2 + i;
        for (qdc = ntohs((unsigned short)hp->qdcount); qdc--; cp += i + QFIXEDSZ) {
                if ((i = dn_skipname(cp, end)) < 0 ) {
                        php_dns_free_handle(handle);
@@ -1107,7 +1103,7 @@ PHP_FUNCTION(dns_get_mx)
                        continue;
                }
                GETSHORT(weight, cp);
-               if ((i = dn_expand(ans, end, cp, buf, sizeof(buf)-1)) < 0) {
+               if ((i = dn_expand(answer.qb2, end, cp, buf, sizeof(buf)-1)) < 0) {
                        php_dns_free_handle(handle);
                        RETURN_FALSE;
                }