filter Tor exit node from SFS listed IPs

This currently only filters out the IPv4 addresses since we would need
another source for a list of IPv6 addresses along with a more involved
implementation to deal with Stop Forum Spam using /64 bans rather than
/128 bans.

stopforumspam-update

@@ -20,7 +20,9 @@ if [[ $mode == hourly ]]; then
     curl --fail-with-body https://www.stopforumspam.com/downloads/listed_ip_1.zip | gunzip > stopforumspam-listed_ip_1_ipv46.txt.new
     mv stopforumspam-listed_ip_1_ipv46.txt.new stopforumspam-listed_ip_1_ipv46.txt
 
-    sort -u stopforumspam-listed_ip_30_ipv46.txt stopforumspam-listed_ip_1_ipv46.txt | awk '{ print $1 " 1;" }' > stopforumspam-listed_ip_merged_ipv46.conf
+    curl --fail-with-body https://check.torproject.org/torbulkexitlist | sort -u > torbulkexitlist.txt
+
+    sort -u stopforumspam-listed_ip_30_ipv46.txt stopforumspam-listed_ip_1_ipv46.txt | comm -1 -3 torbulkexitlist.txt - | awk '{ print $1 " 1;" }' > stopforumspam-listed_ip_merged_ipv46.conf
 
     nginx -s reload
 fi