[tor-commits] [tor/release-0.4.0] 30001: Fix a race condition in test_dir_handle_get.c

[asn at torproject.org]

commit 367dd9cf0226c087d49225a20415e9a199d2d71f
Author: Nick Mathewson <nickm at torproject.org>
Date:   Wed Apr 3 10:16:18 2019 -0400

    30001: Fix a race condition in test_dir_handle_get.c
    
    Previously we used time(NULL) to set the Expires: header in our HTTP
    responses.  This made the actual contents of that header untestable,
    since the unit tests have no good way to override time(), or to see
    what time() was at the exact moment of the call to time() in
    dircache.c.
    
    This gave us a race in dir_handle_get/status_vote_next_bandwidth,
    where the time() call in dircache.c got one value, and the call in
    the tests got another value.
    
    I'm applying our regular solution here: using approx_time() so that
    the value stays the same between the code and the test.  Since
    approx_time() is updated on every event callback, we shouldn't be
    losing any accuracy here.
    
    Fixes bug 30001. Bug introduced in fb4a40c32c4a7e5; not in any
    released Tor.
---
 changes/bug30001                | 4 ++++
 src/feature/dircache/dircache.c | 2 +-
 src/test/test_dir_handle_get.c  | 2 +-
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/changes/bug30001 b/changes/bug30001
new file mode 100644
index 000000000..e3304701e
--- /dev/null
+++ b/changes/bug30001
@@ -0,0 +1,4 @@
+  o Minor features (testing):
+    - Use the approx_time() function when setting the "Expires" header
+      in directory replies, to make them more testable. Needed for
+      ticket 30001.
diff --git a/src/feature/dircache/dircache.c b/src/feature/dircache/dircache.c
index caa085dd6..1123d034e 100644
--- a/src/feature/dircache/dircache.c
+++ b/src/feature/dircache/dircache.c
@@ -124,7 +124,7 @@ write_http_response_header_impl(dir_connection_t *conn, ssize_t length,
                            long cache_lifetime)
 {
   char date[RFC1123_TIME_LEN+1];
-  time_t now = time(NULL);
+  time_t now = approx_time();
   buf_t *buf = buf_new_with_capacity(1024);
 
   tor_assert(conn);
diff --git a/src/test/test_dir_handle_get.c b/src/test/test_dir_handle_get.c
index c3a17e730..e57bd0258 100644
--- a/src/test/test_dir_handle_get.c
+++ b/src/test/test_dir_handle_get.c
@@ -2526,7 +2526,7 @@ test_dir_handle_get_status_vote_next_bandwidth(void* data)
 
   /* Check cache lifetime */
   char expbuf[RFC1123_TIME_LEN+1];
-  time_t now = time(NULL);
+  time_t now = approx_time();
   /* BANDWIDTH_CACHE_LIFETIME is defined in dircache.c. */
   format_rfc1123_time(expbuf, (time_t)(now + 30*60));
   char *expires = NULL;