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, 5 insertions, 0 deletions

diff --git a/src/or/channel.c b/src/or/channel.c
index f547aea1b3..fdd3f81e81 100644
--- a/src/or/channel.c
+++ b/src/or/channel.c
@@ -2583,6 +2583,7 @@ channel_do_open_actions(channel_t *chan)
     if (!router_get_by_id_digest(chan->identity_digest)) {
       if (channel_get_addr_if_possible(chan, &remote_addr)) {
         char *transport_name = NULL;
+        channel_tls_t *tlschan = BASE_CHAN_TO_TLS(chan);
         if (chan->get_transport_name(chan, &transport_name) < 0)
           transport_name = NULL;
 
@@ -2590,6 +2591,10 @@ channel_do_open_actions(channel_t *chan)
                                &remote_addr, transport_name,
                                now);
         tor_free(transport_name);
+        /* Notify the DoS subsystem of a new client. */
+        if (tlschan && tlschan->conn) {
+          dos_new_client_conn(tlschan->conn);
+        }
       }
       /* Otherwise the underlying transport can't tell us this, so skip it */
     }