bugfix: Check to prevent duplicate mesh hostnames when reserving DHCP reservations (#226)

* bugfix: Check for existing hostnames on the network in DHCP reservations

fixes #216
*additional check for existing hostname when creating new DHCP lease.
checks hosts_olsr file if entered hostname already exists or not on the connected network(s).
outputs info saying such and gives advice to prefix hostname with callsign.

* change to use =~ /\s$host\S/i

* Reworded warning message

* moved the position of the hostname check to only when you click "add" on the DHCP leases page.

this stops it checking all the previously entered hostnames.

files/www/cgi-bin/ports

@@ -284,10 +284,28 @@ foreach $val (@list)
     $host = $parms{"dhcp${val}_host"};
     $ip   = $parms{"dhcp${val}_ip"};
     $mac  = $parms{"dhcp${val}_mac"};
-
+    $foundHost = 0;
     if($val eq "_add")
     {
-	next unless ($host or $ip or $mac) and ($parms{dhcp_add} or $parms{button_save});
+	if($host) {
+		#my $foundHost = 0;
+		my $olsrFile = 0;
+        	$olsrFile = 1 if -f "/var/run/hosts_olsr";
+        	if($olsrFile) {
+			open(my $hostFile, "<", "/var/run/hosts_olsr");
+			while(<$hostFile>) {
+            			if($_ =~ /\s$host\s/i) {
+					$foundHost = 1;
+              				last;
+            			}
+          		}
+         		close($hostFile);
+         		push(@dhcp_err, "$val <font color='red'>Warning!</font> '$host' is already in use!<br>" .
+         		"Please choose another hostname.<br>" .
+            		"Prefixing the hostname with your callsign will help prevent duplicates on the network.") if $foundHost == 1;
+        	}
+	}
+	next unless ($host or $ip or $mac or $foundHost) and ($parms{dhcp_add} or $parms{button_save});
     }
     else
     {
@@ -302,6 +320,7 @@ foreach $val (@list)
 
     if(validate_hostname($host))
     {
+	if(! $foundHost) {
 		push(@dhcp_err, "$val hostname '$host' is already in use") if (lc $host eq lc $node || lc $host eq lc $tactical);
         	foreach my $key (keys %hosts) {
            		if ( lc $key eq lc $host ){
@@ -310,6 +329,7 @@ foreach $val (@list)
            		}
         	}
 	}
+    }
     else
     {
 	if($host) { push @dhcp_err, "$val '$host' is not a valid hostname" }