2.4.x fix mood change

changes-entries/h2_remove_unscheduling.txt

@@ -0,0 +1,6 @@
+  *) mod_http2: removing unscheduling of ongonig tasks when
+     connection shows potential abuse by a client. This proved
+     counter-productive and the abuse detection can false flag
+     requests using server-side-events.
+     Fixes <https://github.com/icing/mod_h2/issues/231>.
+     [Stefan Eissing]

modules/http2/h2_mplx.c

@@ -861,102 +861,6 @@ void h2_mplx_s_task_done(h2_mplx *m, h2_task *task, h2_task **ptask)
  * h2_mplx DoS protection
  ******************************************************************************/
 
-static int m_timed_out_busy_iter(void *data, void *val)
-{
-    stream_iter_ctx *ctx = data;
-    h2_stream *stream = val;
-    if (h2_task_has_started(stream->task) && !stream->task->worker_done
-        && (ctx->now - stream->task->started_at) > stream->task->timeout) {
-        /* timed out stream occupying a worker, found */
-        ctx->stream = stream;
-        return 0;
-    }
-    return 1;
-}
-
-static h2_stream *m_get_timed_out_busy_stream(h2_mplx *m) 
-{
-    stream_iter_ctx ctx;
-    ctx.m = m;
-    ctx.stream = NULL;
-    ctx.now = apr_time_now();
-    h2_ihash_iter(m->streams, m_timed_out_busy_iter, &ctx);
-    return ctx.stream;
-}
-
-static int m_latest_repeatable_unsubmitted_iter(void *data, void *val)
-{
-    stream_iter_ctx *ctx = data;
-    h2_stream *stream = val;
-
-    if (!stream->task) goto leave;
-    if (!h2_task_has_started(stream->task) || stream->task->worker_done) goto leave;
-    if (h2_stream_is_ready(stream)) goto leave;
-    if (stream->task->redo) {
-        ++ctx->count;
-        goto leave;
-    }
-    if (h2_task_can_redo(stream->task)) {
-        /* this task occupies a worker, the response has not been submitted 
-         * yet, not been cancelled and it is a repeatable request
-         * -> we could redo it later */
-        if (!ctx->stream 
-            || (ctx->stream->task->started_at < stream->task->started_at)) {
-            /* we did not have one or this one was started later */
-            ctx->stream = stream;
-        }
-    }
-leave:
-    return 1;
-}
-
-static apr_status_t m_assess_task_to_throttle(h2_task **ptask, h2_mplx *m) 
-{
-    stream_iter_ctx ctx;
-
-    /* count the running tasks already marked for redo and get one that could
-     * be throttled */
-    *ptask = NULL;
-    ctx.m = m;
-    ctx.stream = NULL;
-    ctx.count = 0;
-    h2_ihash_iter(m->streams, m_latest_repeatable_unsubmitted_iter, &ctx);
-    if (m->tasks_active - ctx.count > m->limit_active) {
-        /* we are above the limit of running tasks, accounting for the ones
-         * already throttled. */
-        if (ctx.stream && ctx.stream->task) {
-            *ptask = ctx.stream->task;
-            return APR_EAGAIN;
-        }
-        /* above limit, be seeing no candidate for easy throttling */
-        if (m_get_timed_out_busy_stream(m)) {
-            /* Too many busy workers, unable to cancel enough streams
-             * and with a busy, timed out stream, we tell the client
-             * to go away... */
-            return APR_TIMEUP;
-        }
-    }
-    return APR_SUCCESS;
-}
-
-static apr_status_t m_unschedule_slow_tasks(h2_mplx *m) 
-{
-    h2_task *task;
-    apr_status_t rv;
-
-    /* Try to get rid of streams that occupy workers. Look for safe requests
-     * that are repeatable. If none found, fail the connection.
-     */
-    while (APR_EAGAIN == (rv = m_assess_task_to_throttle(&task, m))) {
-        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, m->c, 
-                      "h2_mplx(%s): unschedule, resetting task for redo later",
-                      task->id);
-        task->redo = 1;
-        h2_task_rst(task, H2_ERR_CANCEL);
-    }
-    return rv;
-}
-
 static apr_status_t s_mplx_be_happy(h2_mplx *m, h2_task *task)
 {
     apr_time_t now;            
@@ -1006,9 +910,6 @@ static apr_status_t m_be_annoyed(h2_mplx *m)
                       m->id, m->limit_active);
     }
 
-    if (m->tasks_active > m->limit_active) {
-        status = m_unschedule_slow_tasks(m);
-    }
     return status;
 }
 

modules/http2/h2_version.h

@@ -27,7 +27,7 @@
  * @macro
  * Version number of the http2 module as c string
  */
-#define MOD_HTTP2_VERSION "1.15.26"
+#define MOD_HTTP2_VERSION "1.15.28"
 
 /**
  * @macro