check_dig not working as expected (plugins 1.4.15)

[Benjamin KRAFT]

Hello,

I just wanted to pop-out if nobody already did that check_dig doesn't behave like it should on my centos machine.

I was trying to validate the fact that my authoritative server at 80.92.90.249 resolves my website to the corresponding ip address, like this :

[root at nagg ns1]# /usr/local/nagios/libexec/check_dig -H 80.92.90.249 -l www.dotnul.com -a 78.46.96.219 -A "+tcp"
DNS OK - 0.009 seconds response time (www.dotnul.com.  3600 IN A 78.46.96.219)|time=0.009035s;;;0.000000

That's ok - but I noticed when I misspasted the expected return IP address, that the check returns OK if I put the address of the queried server as expected result.

[root at nagg ns1]# /usr/local/nagios/libexec/check_dig -H 80.92.90.249 -l www.dotnul.com -a 80.92.90.249 -A "+tcp"
DNS OK - 0.006 seconds response time (;; SERVER: 80.92.90.249#53(80.92.90.249))|time=0.006368s;;;0.000000

The return of the dig query is :

[root at nagg ns1]# dig www.dotnul.com @80.92.90.249 +tcp

; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_4.2 <<>> www.dotnul.com @80.92.90.249 +tcp
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1842
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 3, ADDITIONAL: 0

;; QUESTION SECTION:
;www.dotnul.com.			IN	A

;; ANSWER SECTION:
www.dotnul.com.		3600	IN	A	78.46.96.219

;; AUTHORITY SECTION:
dotnul.com.		86400	IN	NS	ether.dotnul.org.
dotnul.com.		86400	IN	NS	hypnos.dotnul.org.
dotnul.com.		86400	IN	NS	tanathos.dotnul.org.

;; Query time: 1 msec
;; SERVER: 80.92.90.249#53(80.92.90.249)
;; WHEN: Sun Apr 24 13:44:12 2011
;; MSG SIZE  rcvd: 122

By having an eye on nagios-plugins-1.4.15/plugins/check_dig.c, it looks like the following code is involved :

  for(i = 0; i < chld_out.lines; i++) {
    /* the server is responding, we just got the host name... */
    if (strstr (chld_out.line[i], ";; ANSWER SECTION:")) {

      /* loop through the whole 'ANSWER SECTION' */
      for(; i < chld_out.lines; i++) {
        /* get the host address */
        if (verbose)
          printf ("%s\n", chld_out.line[i]);

        if (strstr (chld_out.line[i], (expected_address == NULL ? query_address : expected_address)) != NULL) {
          msg = chld_out.line[i];
          result = STATE_OK;

          /* Translate output TAB -> SPACE */
          t = msg;
          while ((t = strchr(t, '\t')) != NULL) *t = ' ';
          break;
        }
      }

      if (result == STATE_UNKNOWN) {
        msg = (char *)_("Server not found in ANSWER SECTION");
        result = STATE_WARNING;
      }

      /* we found the answer section, so break out of the loop */
      break;
    }
  }

Shouldn't the command stop reading any following line beginning with ";; " after finding the ANSWER section instead of searching a match in everything until end of chld_out ?

Kind regards,

Benjamin


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