--- webalizer.h.orig	Wed Jun 30 19:03:36 1999
+++ webalizer.h	Wed Jun 30 21:21:59 1999
@@ -250,6 +250,9 @@
 void    top_search_table();                         /* top n search strs   */
 static  char *save_opt(char *);                     /* save conf option    */
 u_long  ctry_idx(char *);                           /* index domain name   */
+
+void lookup_host_name(char* host, int max_host_size); /* inverse lookup of IPs */
+void lookup_sigalrm(); /* need this to time out long DNS lookups */
 u_long  tot_visit(HNODEPTR *);                      /* calc total visits   */
 int     ispage(char *);                             /* check for HTML type */
 void    update_entry(char *);                       /* update entry total  */
--- webalizer.c.orig	Wed Jun 30 20:58:39 1999
+++ webalizer.c	Wed Jun 30 21:25:35 1999
@@ -39,6 +39,16 @@
 #include <sys/utsname.h>
 #include <sys/times.h>
 
+/* needed for inverse lookup */
+
+#include <netdb.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <search.h>
+#include <setjmp.h>
+#include <signal.h>
+
 /* ensure getopt */
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
@@ -209,6 +219,11 @@
 NLISTPTR html_end      = NULL;                /* after everything else    */
 NLISTPTR page_type     = NULL;                /* page view types          */
 
+int reverse_lookup = 0;               /* enable reverse lookup of IP's */
+int dns_cache = 8192;		     /* size of the DNS hash table*/
+int dns_timeout = 2;		     /* DNS timout in seconds */
+jmp_buf jumper;                      /* need this to jump out the signal hanlder */
+
 /*********************************************/
 /* MAIN - start here                         */
 /*********************************************/
@@ -297,6 +312,11 @@
       }
    }
 
+   if(reverse_lookup)
+   {
+      hcreate(dns_cache);
+   }
+
    if (argc - optind != 0) log_fname = argv[optind];
 
    /* setup our internal variables */
@@ -567,6 +587,9 @@
          /* DO SOME PRE-PROCESS FORMATTING            */
          /*********************************************/
 
+         if (reverse_lookup)
+            lookup_host_name(log_rec.hostname, sizeof(log_rec.hostname));
+
          /* lowercase hostname */
          cp1 = log_rec.hostname;
          while (*cp1 != '\0')
@@ -1168,6 +1191,92 @@
    }
 }
 
+void lookup_host_name(char* host, int max_host_size)
+{
+  struct in_addr in;
+  struct hostent *h;
+  static ENTRY e, *ep;
+  char* e_ip;
+  char* e_host = "";
+  int ip_len;
+  int host_len;
+
+  e.key = host;
+  ep = hsearch(e, FIND);
+  
+  if(debug_mode)
+   fprintf(stderr, "Looking up %s\n", e.key);
+  
+  if(ep)
+   {
+    if(debug_mode)
+     fprintf(stderr, "Found %s for %s in the DNS cache\n", ep->data, e.key);
+    
+    strncpy(host, ep->data, max_host_size);
+    return;
+   }
+
+  inet_aton(host, &in);
+ 
+  if(!setjmp(jumper))
+   {
+    signal(SIGALRM, lookup_sigalrm);
+    alarm(dns_timeout);
+    h = gethostbyaddr((char*)&in, sizeof(struct in_addr), AF_INET);
+    alarm(0);
+   }
+  else
+  {
+   if(verbose)
+    fprintf(stderr, "DNS request timed out for %s\n", e.key);
+   h = NULL;
+  }
+
+  e_ip = (char*)malloc(ip_len = strlen(host) + 1);
+  if(!e_ip)
+   {
+    if (verbose)
+    fprintf(stderr, "Warning: malloc() failed in lookup_host_name()\n");
+    return;
+   }
+ 
+  memcpy(e_ip, host, ip_len);
+ 
+  if(h)
+   {
+    e_host = (char*)malloc(host_len = strlen(h->h_name) + 1);
+    if(!e_host)
+    {
+     if (verbose)
+     fprintf(stderr, "Warning: malloc() failed in lookup_host_name()\n");
+     return;
+    }
+
+    memcpy(e_host, h->h_name, host_len );
+    memcpy(host, h->h_name, (max_host_size < host_len) ? 
+      max_host_size : (host_len + 1));
+   }
+  else
+   {
+    e_host = (char*)malloc(host_len = strlen(host) + 1);
+    if(!e_host)
+    {
+     if (verbose)
+     fprintf(stderr, "Warning: malloc() failed in lookup_host_name()\n");
+     return;
+    }
+    memcpy(e_host, host, host_len);
+   }
+
+  e.key = e_ip;
+  e.data = e_host;
+  if(!hsearch(e, ENTER))
+   {
+    free(e_ip);
+    free(e_host);
+   }
+}
+
 /*********************************************/
 /* PARSE_RECORD - uhhh, you know...          */
 /*********************************************/
@@ -1402,6 +1511,11 @@
    return 1;     /* maybe a valid record, return with TRUE */
 }
 
+void lookup_sigalrm()
+{
+   longjmp(jumper, 1);
+}
+
 /*********************************************/
 /* CLEAR_MONTH - initalize monthly stuff     */
 /*********************************************/
@@ -1493,7 +1607,10 @@
                      "TopEntry",          /* Top Entry Pages            57  */
                      "TopExit",           /* Top Exit Pages             58  */
                      "TopSearch",         /* Top Search Strings         59  */
-                     "LogType"            /* Log Type (clf or ftp)      60  */
+                     "LogType",           /* Log Type (clf or ftp)      60  */
+                     "ReverseLookup",     /* Do DNS lookup (yes/no)     61  */
+                     "DNSCache",          /* Cache size (8K default)    62  */
+                     "DNSTimeout"         /* Timeout (default 2 sec)    63  */
                    };
 
    FILE *fp;
@@ -1603,6 +1720,9 @@
         case 58: ntop_exit   = atoi(value);        break; /* Top Exit pages */
         case 59: ntop_search = atoi(value);        break; /* Top Search pgs */
         case 60: log_type=(value[0]=='f')?1:0;     break; /* LogType (1=ftp)*/
+        case 61: reverse_lookup=(value[0]=='y')?1:0; break; /* Reverse DNS  */
+        case 62: dns_cache=atoi(value);            break; /* DNS Cache size */
+        case 63: dns_timeout=atoi(value);          break; /* DNS Timeout    */
       }
    }
    fclose(fp);