/ip_addresses: allow grouping IPs by subnet.

app/models/ip_address.rb

@@ -14,14 +14,31 @@ class IpAddress < ApplicationRecord
     q.order(created_at: :desc)
   end
 
-  def self.group_by_ip_addr
-    group(:ip_addr).select("ip_addr, COUNT(*) AS count_all").reorder("count_all DESC, ip_addr")
+  def self.group_by_ip_addr(ipv4_masklen = nil, ipv6_masklen = nil)
+    ipv4_masklen ||= 32
+    ipv6_masklen ||= 128
+
+    q = select(sanitize_sql([<<~SQL, ipv4_masklen, ipv6_masklen]))
+      CASE
+        WHEN family(ip_addr) = 4
+        THEN network(set_masklen(ip_addr, ?))
+        ELSE network(set_masklen(ip_addr, ?))
+      END AS ip_addr,
+      COUNT(*) AS count_all
+    SQL
+
+    q.group("1").reorder("count_all DESC, ip_addr")
   end
 
   def self.group_by_user
     group(:user_id).select("user_id, COUNT(*) AS count_all").reorder("count_all DESC, user_id")
   end
 
+  def to_s
+    # include the subnet mask only when the IP denotes a subnet.
+    ip_addr.size > 1 ? ip_addr.to_string : ip_addr.to_s
+  end
+
   def readonly?
     true
   end