low_speed_limit: improved function for longer time periods

Previously, periods of fast speed between periods of slow speed would
not count and could still erroneously trigger a timeout.

Reported-by: Paul Harris
Fixes #1345
Closes #1390

1 files changed, 30 insertions, 29 deletions

diff --git a/lib/speedcheck.c b/lib/speedcheck.c
index 509c304f4..f0daf82c0 100644
--- a/lib/speedcheck.c
+++ b/lib/speedcheck.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -33,40 +33,41 @@ void Curl_speedinit(struct Curl_easy *data)
   memset(&data->state.keeps_speed, 0, sizeof(struct timeval));
 }
 
+/*
+ * @unittest: 1606
+ */
 CURLcode Curl_speedcheck(struct Curl_easy *data,
                          struct timeval now)
 {
-  if((data->progress.current_speed >= 0) &&
-     data->set.low_speed_time &&
-     (Curl_tvlong(data->state.keeps_speed) != 0) &&
-     (data->progress.current_speed < data->set.low_speed_limit)) {
-    time_t howlong = Curl_tvdiff(now, data->state.keeps_speed);
-    time_t nextcheck = (data->set.low_speed_time * 1000) - howlong;
+  if((data->progress.current_speed >= 0) && data->set.low_speed_time) {
+    if(data->progress.current_speed < data->set.low_speed_limit) {
+      if(!data->state.keeps_speed.tv_sec)
+        /* under the limit at this very moment */
+        data->state.keeps_speed = now;
+      else {
+        /* how long has it been under the limit */
+        time_t howlong = Curl_tvdiff(now, data->state.keeps_speed);
 
-    /* We are now below the "low speed limit". If we are below it
-       for "low speed time" seconds we consider that enough reason
-       to abort the download. */
-    if(nextcheck <= 0) {
-      /* we have been this slow for long enough, now die */
-      failf(data,
-            "Operation too slow. "
-            "Less than %ld bytes/sec transferred the last %ld seconds",
-            data->set.low_speed_limit,
-            data->set.low_speed_time);
-      return CURLE_OPERATION_TIMEDOUT;
+        if(howlong >= data->set.low_speed_time * 1000) {
+          /* too long */
+          failf(data,
+                "Operation too slow. "
+                "Less than %ld bytes/sec transferred the last %ld seconds",
+                data->set.low_speed_limit,
+                data->set.low_speed_time);
+          return CURLE_OPERATION_TIMEDOUT;
+        }
+      }
     }
-    /* wait complete low_speed_time */
-    Curl_expire_latest(data, nextcheck);
+    else
+      /* faster right now */
+      data->state.keeps_speed.tv_sec = 0;
   }
-  else {
-    /* we keep up the required speed all right */
-    data->state.keeps_speed = now;
 
-    if(data->set.low_speed_limit)
-      /* if there is a low speed limit enabled, we set the expire timer to
-         make this connection's speed get checked again no later than when
-         this time is up */
-      Curl_expire_latest(data, data->set.low_speed_time*1000);
-  }
+  if(data->set.low_speed_limit)
+    /* if low speed limit is enabled, set the expire timer to make this
+       connection's speed get checked again in a second */
+    Curl_expire_latest(data, 1000);
+
   return CURLE_OK;
 }