From cfeb1db2fb881db85a11d80e70a1a14c62b46950 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Mon, 14 Mar 2016 12:53:21 -0400
Subject: Add comments to connection_check_event().

---
 src/or/main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/or/main.c b/src/or/main.c
index 1200b55e2e..89e5a512b3 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -506,14 +506,24 @@ connection_is_reading(connection_t *conn)
     (conn->read_event && event_pending(conn->read_event, EV_READ, NULL));
 }
 
+/** Check whether <b>conn</b> is correct in having (or not having) a
+ * read/write event (passed in <b>ev</b). On success, return 0. On failure,
+ * log a warning and return -1. */
 static int
 connection_check_event(connection_t *conn, struct event *ev)
 {
   int bad;
 
   if (conn->type == CONN_TYPE_AP && TO_EDGE_CONN(conn)->is_dns_request) {
+    /* DNS requests which we launch through the dnsserv.c module do not have
+     * any underlying socket or any underlying linked connection, so they
+     * shouldn't have any attached events either.
+     */
     bad = ev != NULL;
   } else {
+    /* Everytyhing else should have an underlying socket, or a linked
+     * connection (which is also tracked with a read_event/write_event pair).
+     */
     bad = ev == NULL;
   }
 
-- 
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