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Re: 2.99.55 caused DoS attack



On Fri, 2003-04-11 at 22:21, Roy Bixler wrote:
> My day today has been rather "interesting" so far.  Campus networking
> twice had to disable the network port for our Z-Mailer 2.99.55 mail
> server due to DoS attack on their name servers.

The function that creates bounce report uses dns to find *local* host
name.  If you have several entries in the "search" line, it issues as
many DNS requests.  This is the fix that I use here:

Index: libc/myhostname.c
===================================================================
RCS file: /cvsroot/zmailer/libc/myhostname.c,v
retrieving revision 1.6
diff -u -r1.6 myhostname.c
--- libc/myhostname.c   2000/11/16 16:58:41     1.6
+++ libc/myhostname.c   2002/11/27 14:57:31
@@ -23,8 +23,8 @@
 #endif
 #include "libc.h"
 
-int
-getmyhostname(namebuf, len)
+static int
+_getmyhostname(namebuf, len)
        char *namebuf;
        int len;
 {
@@ -130,4 +130,25 @@
 #endif
        return 0;
 #endif
+}
+
+int
+getmyhostname(namebuf, len)
+       char *namebuf;
+       int len;
+{
+       int rc;
+       static char *savedname=NULL;
+
+       if (savedname) {
+               strncpy(namebuf, savedname, len);
+               namebuf[len - 1] = 0;
+               return 0;
+       }
+       rc = _getmyhostname(namebuf, len);
+       if (rc == 0) {
+               savedname=(char*)malloc(strlen(namebuf)+1);
+               strcpy(savedname, namebuf);
+       }
+       return rc;
 }


-- 
Eugene Crosser, head of Internet Applications section, +7 501 787 1000
ROL, Teleross, Golden Telecom, http://user.rol.ru/~crosser/

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