dos: Track new and closed OR client connections

Implement a basic connection tracking that counts the number of concurrent
connections when they open and close.

This commit also adds the circuit creation mitigation data structure that will
be needed at later commit to keep track of the circuit rate.

Signed-off-by: David Goulet <dgoulet@torproject.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/or/connection.c b/src/or/connection.c
index 8b00d637f6..15f489c6b4 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -78,6 +78,7 @@
 #include "dirserv.h"
 #include "dns.h"
 #include "dnsserv.h"
+#include "dos.h"
 #include "entrynodes.h"
 #include "ext_orport.h"
 #include "geoip.h"
@@ -687,6 +688,13 @@ connection_free,(connection_t *conn))
                                                   "connection_free");
   }
 #endif
+
+  /* Notify the circuit creation DoS mitigation subsystem that an OR client
+   * connection has been closed. And only do that if we track it. */
+  if (conn->type == CONN_TYPE_OR) {
+    dos_close_client_conn(TO_OR_CONN(conn));
+  }
+
   connection_unregister_events(conn);
   connection_free_(conn);
 }