]> granicus.if.org Git - apache/blobdiff - modules/http2/h2_session.c
mod_http2: push diary to avoid duplicate pushes, cache-digest handling, http2-status...
[apache] / modules / http2 / h2_session.c
index c3456a0654da6254ae50e3e3e9787d20238f4c1b..34575a6b55a1e031a03d41a48be883cdb9977ccd 100644 (file)
 #include <http_core.h>
 #include <http_config.h>
 #include <http_log.h>
+#include <scoreboard.h>
 
 #include "h2_private.h"
+#include "h2_bucket_eoc.h"
+#include "h2_bucket_eos.h"
 #include "h2_config.h"
+#include "h2_ctx.h"
+#include "h2_filter.h"
 #include "h2_h2.h"
 #include "h2_mplx.h"
+#include "h2_push.h"
+#include "h2_request.h"
 #include "h2_response.h"
 #include "h2_stream.h"
 #include "h2_stream_set.h"
 #include "h2_version.h"
 #include "h2_workers.h"
 
+
 static int frame_print(const nghttp2_frame *frame, char *buffer, size_t maxlen);
 
 static int h2_session_status_from_apr_status(apr_status_t rv)
 {
-    switch (rv) {
-        case APR_SUCCESS:
-            return NGHTTP2_NO_ERROR;
-        case APR_EAGAIN:
-        case APR_TIMEUP:
-            return NGHTTP2_ERR_WOULDBLOCK;
-        case APR_EOF:
+    if (rv == APR_SUCCESS) {
+        return NGHTTP2_NO_ERROR;
+    }
+    else if (APR_STATUS_IS_EAGAIN(rv)) {
+        return NGHTTP2_ERR_WOULDBLOCK;
+    }
+    else if (APR_STATUS_IS_EOF(rv)) {
             return NGHTTP2_ERR_EOF;
-        default:
-            return NGHTTP2_ERR_PROTO;
     }
+    return NGHTTP2_ERR_PROTO;
 }
 
-static int stream_open(h2_session *session, int stream_id)
+static void update_window(void *ctx, int stream_id, apr_off_t bytes_read)
+{
+    h2_session *session = (h2_session*)ctx;
+    nghttp2_session_consume(session->ngh2, stream_id, bytes_read);
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
+                  "h2_session(%ld-%d): consumed %ld bytes",
+                  session->id, stream_id, (long)bytes_read);
+}
+
+static apr_status_t h2_session_receive(void *ctx, 
+                                       const char *data, apr_size_t len,
+                                       apr_size_t *readlen);
+
+static int is_accepting_streams(h2_session *session); 
+static void dispatch_event(h2_session *session, h2_session_event_t ev, 
+                             int err, const char *msg);
+
+h2_stream *h2_session_open_stream(h2_session *session, int stream_id)
 {
     h2_stream * stream;
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
+    apr_pool_t *stream_pool;
+    
+    if (session->spare) {
+        stream_pool = session->spare;
+        session->spare = NULL;
+    }
+    else {
+        apr_pool_create(&stream_pool, session->pool);
     }
     
-    stream = h2_mplx_open_io(session->mplx, stream_id);
-    if (stream) {
-        h2_stream_set_add(session->streams, stream);
-        if (stream->id > session->max_stream_received) {
-            session->max_stream_received = stream->id;
-        }
-        
-        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                      "h2_session: stream(%ld-%d): opened",
-                      session->id, stream_id);
+    stream = h2_stream_open(stream_id, stream_pool, session);
+    
+    h2_stream_set_add(session->streams, stream);
+    if (H2_STREAM_CLIENT_INITIATED(stream_id)
+        && stream_id > session->max_stream_received) {
+        ++session->requests_received;
+        session->max_stream_received = stream->id;
+    }
+    
+    return stream;
+}
+
+#ifdef H2_NG2_STREAM_API
+
+/**
+ * Determine the importance of streams when scheduling tasks.
+ * - if both stream depend on the same one, compare weights
+ * - if one stream is closer to the root, prioritize that one
+ * - if both are on the same level, use the weight of their root
+ *   level ancestors
+ */
+static int spri_cmp(int sid1, nghttp2_stream *s1, 
+                    int sid2, nghttp2_stream *s2, h2_session *session)
+{
+    nghttp2_stream *p1, *p2;
+    
+    p1 = nghttp2_stream_get_parent(s1);
+    p2 = nghttp2_stream_get_parent(s2);
+    
+    if (p1 == p2) {
+        int32_t w1, w2;
         
-        return 0;
+        w1 = nghttp2_stream_get_weight(s1);
+        w2 = nghttp2_stream_get_weight(s2);
+        return w2 - w1;
     }
+    else if (!p1) {
+        /* stream 1 closer to root */
+        return -1;
+    }
+    else if (!p2) {
+        /* stream 2 closer to root */
+        return 1;
+    }
+    return spri_cmp(sid1, p1, sid2, p2, session);
+}
+
+static int stream_pri_cmp(int sid1, int sid2, void *ctx)
+{
+    h2_session *session = ctx;
+    nghttp2_stream *s1, *s2;
     
-    ap_log_cerror(APLOG_MARK, APLOG_ERR, APR_ENOMEM, session->c,
-                  APLOGNO(02918) 
-                  "h2_session: stream(%ld-%d): unable to create",
-                  session->id, stream_id);
-    return NGHTTP2_ERR_INVALID_STREAM_ID;
+    s1 = nghttp2_session_find_stream(session->ngh2, sid1);
+    s2 = nghttp2_session_find_stream(session->ngh2, sid2);
+
+    if (s1 == s2) {
+        return 0;
+    }
+    else if (!s1) {
+        return 1;
+    }
+    else if (!s2) {
+        return -1;
+    }
+    return spri_cmp(sid1, s1, sid2, s2, session);
+}
+
+#else /* ifdef H2_NG2_STREAM_API */
+
+/* In absence of nghttp2_stream API, which gives information about
+ * priorities since nghttp2 1.3.x, we just sort the streams by
+ * their identifier, aka. order of arrival.
+ */
+static int stream_pri_cmp(int sid1, int sid2, void *ctx)
+{
+    (void)ctx;
+    return sid1 - sid2;
 }
 
-static apr_status_t stream_end_headers(h2_session *session,
-                                       h2_stream *stream, int eos)
+#endif /* (ifdef else) H2_NG2_STREAM_API */
+
+static apr_status_t stream_schedule(h2_session *session,
+                                    h2_stream *stream, int eos)
 {
     (void)session;
-    return h2_stream_write_eoh(stream, eos);
+    return h2_stream_schedule(stream, eos, h2_session_push_enabled(session), 
+                              stream_pri_cmp, session);
 }
 
-static apr_status_t send_data(h2_session *session, const char *data, 
-                              apr_size_t length);
-
 /*
  * Callback when nghttp2 wants to send bytes back to the client.
  */
@@ -100,14 +188,15 @@ static ssize_t send_cb(nghttp2_session *ngh2,
                        int flags, void *userp)
 {
     h2_session *session = (h2_session *)userp;
-    apr_status_t status = send_data(session, (const char *)data, length);
+    apr_status_t status;
     
     (void)ngh2;
     (void)flags;
+    status = h2_conn_io_write(&session->io, (const char *)data, length);
     if (status == APR_SUCCESS) {
         return length;
     }
-    if (status == APR_EAGAIN || status == APR_TIMEUP) {
+    if (APR_STATUS_IS_EAGAIN(status)) {
         return NGHTTP2_ERR_WOULDBLOCK;
     }
     ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, session->c,
@@ -122,16 +211,14 @@ static int on_invalid_frame_recv_cb(nghttp2_session *ngh2,
     h2_session *session = (h2_session *)userp;
     (void)ngh2;
     
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
-    }
-    if (APLOGctrace2(session->c)) {
+    if (APLOGcdebug(session->c)) {
         char buffer[256];
         
         frame_print(frame, buffer, sizeof(buffer)/sizeof(buffer[0]));
-        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
-                      "h2_session: callback on_invalid_frame_recv error=%d %s",
-                      error, buffer);
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_session(%ld): recv unknown FRAME[%s], frames=%ld/%ld (r/s)",
+                      session->id, buffer, (long)session->frames_received,
+                     (long)session->frames_sent);
     }
     return 0;
 }
@@ -140,20 +227,21 @@ static int on_data_chunk_recv_cb(nghttp2_session *ngh2, uint8_t flags,
                                  int32_t stream_id,
                                  const uint8_t *data, size_t len, void *userp)
 {
-    int rv;
     h2_session *session = (h2_session *)userp;
+    apr_status_t status = APR_SUCCESS;
     h2_stream * stream;
-    apr_status_t status;
+    int rv;
     
     (void)flags;
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
+    if (!is_accepting_streams(session)) {
+        /* ignore */
+        return 0;
     }
-    stream = h2_stream_set_get(session->streams, stream_id);
+    
+    stream = h2_session_get_stream(session, stream_id);
     if (!stream) {
-        ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c,
-                      APLOGNO(02919) 
-                      "h2_session:  stream(%ld-%d): on_data_chunk for unknown stream",
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_stream(%ld-%d): on_data_chunk for unknown stream",
                       session->id, (int)stream_id);
         rv = nghttp2_submit_rst_stream(ngh2, NGHTTP2_FLAG_NONE, stream_id,
                                        NGHTTP2_INTERNAL_ERROR);
@@ -165,11 +253,12 @@ static int on_data_chunk_recv_cb(nghttp2_session *ngh2, uint8_t flags,
     
     status = h2_stream_write_data(stream, (const char *)data, len);
     ap_log_cerror(APLOG_MARK, APLOG_TRACE1, status, session->c,
-                  "h2_stream(%ld-%d): written DATA, length %d",
-                  session->id, stream_id, (int)len);
+                  "h2_stream(%ld-%d): data_chunk_recv, written %ld bytes",
+                  session->id, stream_id, (long)len);
     if (status != APR_SUCCESS) {
+        update_window(session, stream_id, len);
         rv = nghttp2_submit_rst_stream(ngh2, NGHTTP2_FLAG_NONE, stream_id,
-                                       NGHTTP2_INTERNAL_ERROR);
+                                       H2_STREAM_RST(stream, H2_ERR_INTERNAL_ERROR));
         if (nghttp2_is_fatal(rv)) {
             return NGHTTP2_ERR_CALLBACK_FAILURE;
         }
@@ -177,61 +266,12 @@ static int on_data_chunk_recv_cb(nghttp2_session *ngh2, uint8_t flags,
     return 0;
 }
 
-static int before_frame_send_cb(nghttp2_session *ngh2,
-                                const nghttp2_frame *frame,
-                                void *userp)
-{
-    h2_session *session = (h2_session *)userp;
-    (void)ngh2;
-
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
-    }
-    if (APLOGctrace2(session->c)) {
-        char buffer[256];
-        frame_print(frame, buffer, sizeof(buffer)/sizeof(buffer[0]));
-        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                      "h2_session(%ld): before_frame_send %s", 
-                      session->id, buffer);
-    }
-    return 0;
-}
-
-static int on_frame_send_cb(nghttp2_session *ngh2,
-                            const nghttp2_frame *frame,
-                            void *userp)
-{
-    h2_session *session = (h2_session *)userp;
-    (void)ngh2; (void)frame;
-    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
-                  "h2_session(%ld): on_frame_send", session->id);
-    return 0;
-}
-
-static int on_frame_not_send_cb(nghttp2_session *ngh2,
-                                const nghttp2_frame *frame,
-                                int lib_error_code, void *userp)
-{
-    h2_session *session = (h2_session *)userp;
-    (void)ngh2;
-    
-    if (APLOGctrace2(session->c)) {
-        char buffer[256];
-        
-        frame_print(frame, buffer, sizeof(buffer)/sizeof(buffer[0]));
-        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                      "h2_session: callback on_frame_not_send error=%d %s",
-                      lib_error_code, buffer);
-    }
-    return 0;
-}
-
-static apr_status_t stream_destroy(h2_session *session, 
+static apr_status_t stream_release(h2_session *session, 
                                    h2_stream *stream,
                                    uint32_t error_code) 
 {
     if (!error_code) {
-        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
                       "h2_stream(%ld-%d): handled, closing", 
                       session->id, (int)stream->id);
         if (stream->id > session->max_stream_handled) {
@@ -242,11 +282,13 @@ static apr_status_t stream_destroy(h2_session *session,
         ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
                       "h2_stream(%ld-%d): closing with err=%d %s", 
                       session->id, (int)stream->id, (int)error_code,
-                      nghttp2_strerror(error_code));
+                      h2_h2_err_description(error_code));
+        h2_stream_rst(stream, error_code);
     }
     
-    h2_stream_set_remove(session->streams, stream);
-    return h2_mplx_cleanup_stream(session->mplx, stream);
+    return h2_conn_io_writeb(&session->io,
+                             h2_bucket_eos_create(session->c->bucket_alloc, 
+                                                  stream));
 }
 
 static int on_stream_close_cb(nghttp2_session *ngh2, int32_t stream_id,
@@ -256,36 +298,30 @@ static int on_stream_close_cb(nghttp2_session *ngh2, int32_t stream_id,
     h2_stream *stream;
     
     (void)ngh2;
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
-    }
-    stream = h2_stream_set_get(session->streams, stream_id);
+    stream = h2_session_get_stream(session, stream_id);
     if (stream) {
-        stream_destroy(session, stream, error_code);
+        stream_release(session, stream, error_code);
     }
-    
-    if (error_code) {
-        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                      "h2_stream(%ld-%d): close error %d",
-                      session->id, (int)stream_id, error_code);
-    }
-    
     return 0;
 }
 
 static int on_begin_headers_cb(nghttp2_session *ngh2,
                                const nghttp2_frame *frame, void *userp)
 {
-    /* This starts a new stream. */
-    int rv;
+    h2_session *session = (h2_session *)userp;
+    h2_stream *s;
+    
+    /* We may see HEADERs at the start of a stream or after all DATA
+     * streams to carry trailers. */
     (void)ngh2;
-    rv = stream_open((h2_session *)userp, frame->hd.stream_id);
-    if (rv != NGHTTP2_ERR_CALLBACK_FAILURE) {
-      /* on_header_cb or on_frame_recv_cb will dectect that stream
-         does not exist and submit RST_STREAM. */
-      return 0;
+    s = h2_session_get_stream(session, frame->hd.stream_id);
+    if (s) {
+        /* nop */
+    }
+    else {
+        s = h2_session_open_stream((h2_session *)userp, frame->hd.stream_id);
     }
-    return NGHTTP2_ERR_CALLBACK_FAILURE;
+    return s? 0 : NGHTTP2_ERR_CALLBACK_FAILURE;
 }
 
 static int on_header_cb(nghttp2_session *ngh2, const nghttp2_frame *frame,
@@ -300,11 +336,12 @@ static int on_header_cb(nghttp2_session *ngh2, const nghttp2_frame *frame,
     
     (void)ngh2;
     (void)flags;
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
+    if (!is_accepting_streams(session)) {
+        /* just ignore */
+        return 0;
     }
-    stream = h2_stream_set_get(session->streams,
-                                           frame->hd.stream_id);
+    
+    stream = h2_session_get_stream(session, frame->hd.stream_id);
     if (!stream) {
         ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c,
                       APLOGNO(02920) 
@@ -313,9 +350,9 @@ static int on_header_cb(nghttp2_session *ngh2, const nghttp2_frame *frame,
         return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
     }
     
-    status = h2_stream_write_header(stream,
-                                               (const char *)name, namelen,
-                                               (const char *)value, valuelen);
+    status = h2_stream_add_header(stream, (const char *)name, namelen,
+                                  (const char *)value, valuelen);
+                                    
     if (status != APR_SUCCESS) {
         return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
     }
@@ -331,63 +368,68 @@ static int on_frame_recv_cb(nghttp2_session *ng2s,
                             const nghttp2_frame *frame,
                             void *userp)
 {
-    int rv;
     h2_session *session = (h2_session *)userp;
     apr_status_t status = APR_SUCCESS;
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
-    }
+    h2_stream *stream;
     
+    if (APLOGcdebug(session->c)) {
+        char buffer[256];
+        
+        frame_print(frame, buffer, sizeof(buffer)/sizeof(buffer[0]));
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_session(%ld): recv FRAME[%s], frames=%ld/%ld (r/s)",
+                      session->id, buffer, (long)session->frames_received,
+                     (long)session->frames_sent);
+    }
+
     ++session->frames_received;
-    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
-                  "h2_session(%ld): on_frame_rcv #%ld, type=%d", session->id,
-                  (long)session->frames_received, frame->hd.type);
     switch (frame->hd.type) {
-        case NGHTTP2_HEADERS: {
-            int eos;
-            h2_stream * stream = h2_stream_set_get(session->streams,
-                                                   frame->hd.stream_id);
-            if (stream == NULL) {
-                ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c,
-                              APLOGNO(02921) 
-                              "h2_session:  stream(%ld-%d): HEADERS frame "
-                              "for unknown stream", session->id,
-                              (int)frame->hd.stream_id);
-                rv = nghttp2_submit_rst_stream(ng2s, NGHTTP2_FLAG_NONE,
-                                               frame->hd.stream_id,
-                                               NGHTTP2_INTERNAL_ERROR);
-                if (nghttp2_is_fatal(rv)) {
-                    return NGHTTP2_ERR_CALLBACK_FAILURE;
+        case NGHTTP2_HEADERS:
+            /* This can be HEADERS for a new stream, defining the request,
+             * or HEADER may come after DATA at the end of a stream as in
+             * trailers */
+            stream = h2_session_get_stream(session, frame->hd.stream_id);
+            if (stream) {
+                int eos = (frame->hd.flags & NGHTTP2_FLAG_END_STREAM);
+                
+                if (h2_stream_is_scheduled(stream)) {
+                    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                                  "h2_stream(%ld-%d): TRAILER, eos=%d", 
+                                  session->id, frame->hd.stream_id, eos);
+                    if (eos) {
+                        status = h2_stream_close_input(stream);
+                    }
+                }
+                else {
+                    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                                  "h2_stream(%ld-%d): HEADER, eos=%d", 
+                                  session->id, frame->hd.stream_id, eos);
+                    status = stream_schedule(session, stream, eos);
                 }
-                return 0;
             }
-
-            eos = (frame->hd.flags & NGHTTP2_FLAG_END_STREAM);
-            status = stream_end_headers(session, stream, eos);
-
+            else {
+                status = APR_EINVAL;
+            }
             break;
-        }
-        case NGHTTP2_DATA: {
-            h2_stream * stream = h2_stream_set_get(session->streams,
-                                                   frame->hd.stream_id);
-            if (stream == NULL) {
-                ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c,
-                              APLOGNO(02922) 
-                              "h2_session:  stream(%ld-%d): DATA frame "
-                              "for unknown stream", session->id,
-                              (int)frame->hd.stream_id);
-                rv = nghttp2_submit_rst_stream(ng2s, NGHTTP2_FLAG_NONE,
-                                               frame->hd.stream_id,
-                                               NGHTTP2_INTERNAL_ERROR);
-                if (nghttp2_is_fatal(rv)) {
-                    return NGHTTP2_ERR_CALLBACK_FAILURE;
+        case NGHTTP2_DATA:
+            stream = h2_session_get_stream(session, frame->hd.stream_id);
+            if (stream) {
+                int eos = (frame->hd.flags & NGHTTP2_FLAG_END_STREAM);
+                ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                              "h2_stream(%ld-%d): DATA, len=%ld, eos=%d", 
+                              session->id, frame->hd.stream_id, 
+                              (long)frame->hd.length, eos);
+                if (eos) {
+                    status = h2_stream_close_input(stream);
                 }
-                return 0;
+            }
+            else {
+                status = APR_EINVAL;
             }
             break;
-        }
-        case NGHTTP2_PRIORITY: {
-            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+        case NGHTTP2_PRIORITY:
+            session->reprioritize = 1;
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
                           "h2_session:  stream(%ld-%d): PRIORITY frame "
                           " weight=%d, dependsOn=%d, exclusive=%d", 
                           session->id, (int)frame->hd.stream_id,
@@ -395,7 +437,29 @@ static int on_frame_recv_cb(nghttp2_session *ng2s,
                           frame->priority.pri_spec.stream_id,
                           frame->priority.pri_spec.exclusive);
             break;
-        }
+        case NGHTTP2_WINDOW_UPDATE:
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
+                          "h2_session:  stream(%ld-%d): WINDOW_UPDATE "
+                          "incr=%d", 
+                          session->id, (int)frame->hd.stream_id,
+                          frame->window_update.window_size_increment);
+            break;
+        case NGHTTP2_RST_STREAM:
+            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                          "h2_session(%ld-%d): RST_STREAM by client, errror=%d",
+                          session->id, (int)frame->hd.stream_id,
+                          (int)frame->rst_stream.error_code);
+            stream = h2_session_get_stream(session, frame->hd.stream_id);
+            if (stream && stream->initiated_on) {
+                ++session->pushes_reset;
+            }
+            else {
+                ++session->streams_reset;
+            }
+            break;
+        case NGHTTP2_GOAWAY:
+            dispatch_event(session, H2_SESSION_EV_REMOTE_GOAWAY, 0, NULL);
+            break;
         default:
             if (APLOGctrace2(session->c)) {
                 char buffer[256];
@@ -408,23 +472,10 @@ static int on_frame_recv_cb(nghttp2_session *ng2s,
             break;
     }
 
-    /* only DATA and HEADERS frame can bear END_STREAM flag.  Other
-       frame types may have other flag which has the same value, so we
-       have to check the frame type first.  */
-    if ((frame->hd.type == NGHTTP2_DATA || frame->hd.type == NGHTTP2_HEADERS) &&
-        frame->hd.flags & NGHTTP2_FLAG_END_STREAM) {
-        h2_stream * stream = h2_stream_set_get(session->streams,
-                                               frame->hd.stream_id);
-        if (stream != NULL) {
-            status = h2_stream_write_eos(stream);
-            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, session->c,
-                          "h2_stream(%ld-%d): input closed",
-                          session->id, (int)frame->hd.stream_id);
-        }
-    }
-    
     if (status != APR_SUCCESS) {
-        ap_log_cerror(APLOG_MARK, APLOG_ERR, status, session->c,
+        int rv;
+        
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, session->c,
                       APLOGNO(02923) 
                       "h2_session: stream(%ld-%d): error handling frame",
                       session->id, (int)frame->hd.stream_id);
@@ -434,24 +485,20 @@ static int on_frame_recv_cb(nghttp2_session *ng2s,
         if (nghttp2_is_fatal(rv)) {
             return NGHTTP2_ERR_CALLBACK_FAILURE;
         }
-        return 0;
     }
     
     return 0;
 }
 
-static apr_status_t send_data(h2_session *session, const char *data, 
-                              apr_size_t length)
-{
-    return h2_conn_io_write(&session->io, data, length);
-}
-
 static apr_status_t pass_data(void *ctx, 
-                              const char *data, apr_size_t length)
+                              const char *data, apr_off_t length)
 {
-    return send_data((h2_session*)ctx, data, length);
+    return h2_conn_io_write(&((h2_session*)ctx)->io, data, length);
 }
 
+
+static char immortal_zeros[H2_MAX_PADLEN];
+
 static int on_send_data_cb(nghttp2_session *ngh2, 
                            nghttp2_frame *frame, 
                            const uint8_t *framehd, 
@@ -462,17 +509,18 @@ static int on_send_data_cb(nghttp2_session *ngh2,
     apr_status_t status = APR_SUCCESS;
     h2_session *session = (h2_session *)userp;
     int stream_id = (int)frame->hd.stream_id;
-    const unsigned char padlen = frame->data.padlen;
+    unsigned char padlen;
     int eos;
     h2_stream *stream;
     
     (void)ngh2;
     (void)source;
-    if (session->aborted) {
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
+    if (frame->data.padlen > H2_MAX_PADLEN) {
+        return NGHTTP2_ERR_PROTO;
     }
+    padlen = (unsigned char)frame->data.padlen;
     
-    stream = h2_stream_set_get(session->streams, stream_id);
+    stream = h2_session_get_stream(session, stream_id);
     if (!stream) {
         ap_log_cerror(APLOG_MARK, APLOG_ERR, APR_NOTFOUND, session->c,
                       APLOGNO(02924) 
@@ -481,44 +529,91 @@ static int on_send_data_cb(nghttp2_session *ngh2,
         return NGHTTP2_ERR_CALLBACK_FAILURE;
     }
     
-    status = send_data(session, (const char *)framehd, 9);
-    if (status == APR_SUCCESS) {
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
+                  "h2_stream(%ld-%d): send_data_cb for %ld bytes",
+                  session->id, (int)stream_id, (long)length);
+                  
+    if (h2_conn_io_is_buffered(&session->io)) {
+        status = h2_conn_io_write(&session->io, (const char *)framehd, 9);
+        if (status == APR_SUCCESS) {
+            if (padlen) {
+                status = h2_conn_io_write(&session->io, (const char *)&padlen, 1);
+            }
+            
+            if (status == APR_SUCCESS) {
+                apr_off_t len = length;
+                status = h2_stream_readx(stream, pass_data, session, &len, &eos);
+                if (status == APR_SUCCESS && len != length) {
+                    status = APR_EINVAL;
+                }
+            }
+            
+            if (status == APR_SUCCESS && padlen) {
+                if (padlen) {
+                    status = h2_conn_io_write(&session->io, immortal_zeros, padlen);
+                }
+            }
+        }
+    }
+    else {
+        apr_bucket *b;
+        char *header = apr_pcalloc(stream->pool, 10);
+        memcpy(header, (const char *)framehd, 9);
         if (padlen) {
-            status = send_data(session, (const char *)&padlen, 1);
+            header[9] = (char)padlen;
         }
-
+        b = apr_bucket_pool_create(header, padlen? 10 : 9, 
+                                   stream->pool, session->c->bucket_alloc);
+        status = h2_conn_io_writeb(&session->io, b);
+        
         if (status == APR_SUCCESS) {
-            apr_size_t len = length;
-            status = h2_stream_readx(stream, pass_data, session, 
-                                     &len, &eos);
+            apr_off_t len = length;
+            status = h2_stream_read_to(stream, session->io.output, &len, &eos);
             if (status == APR_SUCCESS && len != length) {
                 status = APR_EINVAL;
             }
         }
-        
+            
         if (status == APR_SUCCESS && padlen) {
-            if (padlen) {
-                char pad[256];
-                memset(pad, 0, padlen);
-                status = send_data(session, pad, padlen);
-            }
+            b = apr_bucket_immortal_create(immortal_zeros, padlen, 
+                                           session->c->bucket_alloc);
+            status = h2_conn_io_writeb(&session->io, b);
         }
     }
     
+    
     if (status == APR_SUCCESS) {
+        stream->data_frames_sent++;
+        h2_conn_io_consider_flush(&session->io);
         return 0;
     }
-    else if (status != APR_EOF) {
-        ap_log_cerror(APLOG_MARK, APLOG_ERR, status, session->c,
+    else {
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, session->c,
                       APLOGNO(02925) 
                       "h2_stream(%ld-%d): failed send_data_cb",
                       session->id, (int)stream_id);
-        return NGHTTP2_ERR_CALLBACK_FAILURE;
     }
     
     return h2_session_status_from_apr_status(status);
 }
 
+static int on_frame_send_cb(nghttp2_session *ngh2, 
+                            const nghttp2_frame *frame,
+                            void *user_data)
+{
+    h2_session *session = user_data;
+    if (APLOGcdebug(session->c)) {
+        char buffer[256];
+        
+        frame_print(frame, buffer, sizeof(buffer)/sizeof(buffer[0]));
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_session(%ld): sent FRAME[%s], frames=%ld/%ld (r/s)",
+                      session->id, buffer, (long)session->frames_received,
+                     (long)session->frames_sent);
+    }
+    ++session->frames_sent;
+    return 0;
+}
 
 #define NGH2_SET_CALLBACK(callbacks, name, fn)\
 nghttp2_session_callbacks_set_##name##_callback(callbacks, fn)
@@ -537,55 +632,215 @@ static apr_status_t init_callbacks(conn_rec *c, nghttp2_session_callbacks **pcb)
     NGH2_SET_CALLBACK(*pcb, on_frame_recv, on_frame_recv_cb);
     NGH2_SET_CALLBACK(*pcb, on_invalid_frame_recv, on_invalid_frame_recv_cb);
     NGH2_SET_CALLBACK(*pcb, on_data_chunk_recv, on_data_chunk_recv_cb);
-    NGH2_SET_CALLBACK(*pcb, before_frame_send, before_frame_send_cb);
-    NGH2_SET_CALLBACK(*pcb, on_frame_send, on_frame_send_cb);
-    NGH2_SET_CALLBACK(*pcb, on_frame_not_send, on_frame_not_send_cb);
     NGH2_SET_CALLBACK(*pcb, on_stream_close, on_stream_close_cb);
     NGH2_SET_CALLBACK(*pcb, on_begin_headers, on_begin_headers_cb);
     NGH2_SET_CALLBACK(*pcb, on_header, on_header_cb);
     NGH2_SET_CALLBACK(*pcb, send_data, on_send_data_cb);
-    
+    NGH2_SET_CALLBACK(*pcb, on_frame_send, on_frame_send_cb);
+
     return APR_SUCCESS;
 }
 
-static h2_session *h2_session_create_int(conn_rec *c,
-                                         request_rec *r,
-                                         h2_config *config, 
-                                         h2_workers *workers)
+static void h2_session_cleanup(h2_session *session)
 {
-    nghttp2_session_callbacks *callbacks = NULL;
-    nghttp2_option *options = NULL;
+    AP_DEBUG_ASSERT(session);
+    /* This is an early cleanup of the session that may
+     * discard what is no longer necessary for *new* streams
+     * and general HTTP/2 processing.
+     * At this point, all frames are in transit or somehwere in
+     * our buffers or passed down output filters.
+     * h2 streams might still being written out.
+     */
+    if (session->c) {
+        h2_ctx_clear(session->c);
+    }
+    if (session->ngh2) {
+        nghttp2_session_del(session->ngh2);
+        session->ngh2 = NULL;
+    }
+    if (session->spare) {
+        apr_pool_destroy(session->spare);
+        session->spare = NULL;
+    }
+}
 
-    apr_pool_t *pool = NULL;
-    apr_status_t status = apr_pool_create(&pool, r? r->pool : c->pool);
-    h2_session *session;
-    if (status != APR_SUCCESS) {
-        return NULL;
+static void h2_session_destroy(h2_session *session)
+{
+    AP_DEBUG_ASSERT(session);
+    h2_session_cleanup(session);
+
+    if (APLOGctrace1(session->c)) {
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                      "h2_session(%ld): destroy, %d streams open",
+                      session->id, (int)h2_stream_set_size(session->streams));
+    }
+    if (session->mplx) {
+        h2_mplx_set_consumed_cb(session->mplx, NULL, NULL);
+        h2_mplx_release_and_join(session->mplx, session->iowait);
+        session->mplx = NULL;
+    }
+    if (session->streams) {
+        h2_stream_set_destroy(session->streams);
+        session->streams = NULL;
+    }
+    if (session->pool) {
+        apr_pool_destroy(session->pool);
     }
+}
 
-    session = apr_pcalloc(pool, sizeof(h2_session));
-    if (session) {
-        int rv;
-        session->id = c->id;
-        session->c = c;
-        session->r = r;
-        
-        session->max_stream_count = h2_config_geti(config, H2_CONF_MAX_STREAMS);
-        session->max_stream_mem = h2_config_geti(config, H2_CONF_STREAM_MAX_MEM);
+static apr_status_t h2_session_shutdown(h2_session *session, int reason, const char *msg)
+{
+    apr_status_t status = APR_SUCCESS;
+    const char *err = msg;
+    
+    AP_DEBUG_ASSERT(session);
+    if (!err && reason) {
+        err = nghttp2_strerror(reason);
+    }
+    nghttp2_submit_goaway(session->ngh2, NGHTTP2_FLAG_NONE, 
+                          h2_mplx_get_max_stream_started(session->mplx), 
+                          reason, (uint8_t*)err, err? strlen(err):0);
+    status = nghttp2_session_send(session->ngh2);
+    h2_conn_io_flush(&session->io);
+    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                  "session(%ld): sent GOAWAY, err=%d, msg=%s", 
+                  session->id, reason, err? err : "");
+    dispatch_event(session, H2_SESSION_EV_LOCAL_GOAWAY, reason, err);
+    return status;
+}
 
-        session->pool = pool;
-        
-        status = apr_thread_cond_create(&session->iowait, session->pool);
-        if (status != APR_SUCCESS) {
-            return NULL;
+static apr_status_t session_pool_cleanup(void *data)
+{
+    h2_session *session = data;
+    /* On a controlled connection shutdown, this gets never
+     * called as we deregister and destroy our pool manually.
+     * However when we have an async mpm, and handed it our idle
+     * connection, it will just cleanup once the connection is closed
+     * from the other side (and sometimes even from out side) and
+     * here we arrive then.
+     */
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                  "session(%ld): pool_cleanup", session->id);
+    
+    if (session->state != H2_SESSION_ST_DONE 
+        && session->state != H2_SESSION_ST_LOCAL_SHUTDOWN) {
+        /* Not good. The connection is being torn down and we have
+         * not sent a goaway. This is considered a protocol error and
+         * the client has to assume that any streams "in flight" may have
+         * been processed and are not safe to retry.
+         * As clients with idle connection may only learn about a closed
+         * connection when sending the next request, this has the effect
+         * that at least this one request will fail.
+         */
+        ap_log_cerror(APLOG_MARK, APLOG_WARNING, 0, session->c,
+                      "session(%ld): connection disappeared without proper "
+                      "goodbye, clients will be confused, should not happen", 
+                      session->id);
+    }
+    /* keep us from destroying the pool, since that is already ongoing. */
+    session->pool = NULL;
+    h2_session_destroy(session);
+    return APR_SUCCESS;
+}
+
+static void *session_malloc(size_t size, void *ctx)
+{
+    h2_session *session = ctx;
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE6, 0, session->c,
+                  "h2_session(%ld): malloc(%ld)",
+                  session->id, (long)size);
+    return malloc(size);
+}
+
+static void session_free(void *p, void *ctx)
+{
+    h2_session *session = ctx;
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE6, 0, session->c,
+                  "h2_session(%ld): free()",
+                  session->id);
+    free(p);
+}
+
+static void *session_calloc(size_t n, size_t size, void *ctx)
+{
+    h2_session *session = ctx;
+
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE6, 0, session->c,
+                  "h2_session(%ld): calloc(%ld, %ld)",
+                  session->id, (long)n, (long)size);
+    return calloc(n, size);
+}
+
+static void *session_realloc(void *p, size_t size, void *ctx)
+{
+    h2_session *session = ctx;
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE6, 0, session->c,
+                  "h2_session(%ld): realloc(%ld)",
+                  session->id, (long)size);
+    return realloc(p, size);
+}
+
+static h2_session *h2_session_create_int(conn_rec *c,
+                                         request_rec *r,
+                                         h2_ctx *ctx, 
+                                         h2_workers *workers)
+{
+    nghttp2_session_callbacks *callbacks = NULL;
+    nghttp2_option *options = NULL;
+    uint32_t n;
+
+    apr_pool_t *pool = NULL;
+    apr_status_t status = apr_pool_create(&pool, c->pool);
+    h2_session *session;
+    if (status != APR_SUCCESS) {
+        return NULL;
+    }
+
+    session = apr_pcalloc(pool, sizeof(h2_session));
+    if (session) {
+        int rv;
+        nghttp2_mem *mem;
+        
+        session->id = c->id;
+        session->c = c;
+        session->r = r;
+        session->s = h2_ctx_server_get(ctx);
+        session->config = h2_config_sget(session->s);
+        
+        session->state = H2_SESSION_ST_INIT;
+        
+        session->pool = pool;
+        apr_pool_pre_cleanup_register(pool, session, session_pool_cleanup);
+        
+        session->max_stream_count = h2_config_geti(session->config, H2_CONF_MAX_STREAMS);
+        session->max_stream_mem = h2_config_geti(session->config, H2_CONF_STREAM_MAX_MEM);
+        session->timeout_secs = h2_config_geti(session->config, H2_CONF_TIMEOUT_SECS);
+        if (session->timeout_secs <= 0) {
+            session->timeout_secs = apr_time_sec(session->s->timeout);
+        }
+        session->keepalive_secs = h2_config_geti(session->config, H2_CONF_KEEPALIVE_SECS);
+        if (session->keepalive_secs <= 0) {
+            session->keepalive_secs = apr_time_sec(session->s->keep_alive_timeout);
+        }
+        
+        status = apr_thread_cond_create(&session->iowait, session->pool);
+        if (status != APR_SUCCESS) {
+            return NULL;
         }
         
-        session->streams = h2_stream_set_create(session->pool);
+        session->streams = h2_stream_set_create(session->pool, session->max_stream_count);
         
         session->workers = workers;
-        session->mplx = h2_mplx_create(c, session->pool, workers);
+        session->mplx = h2_mplx_create(c, session->pool, session->config, workers);
         
-        h2_conn_io_init(&session->io, c);
+        h2_mplx_set_consumed_cb(session->mplx, update_window, session);
+        
+        /* Install the connection input filter that feeds the session */
+        session->cin = h2_filter_cin_create(session->pool, h2_session_receive, session);
+        ap_add_input_filter("H2_IN", session->cin, r, c);
+
+        h2_conn_io_init(&session->io, c, session->config, session->pool);
         session->bbtmp = apr_brigade_create(session->pool, c->bucket_alloc);
         
         status = init_callbacks(c, &callbacks);
@@ -604,16 +859,27 @@ static h2_session *h2_session_create_int(conn_rec *c,
             h2_session_destroy(session);
             return NULL;
         }
-
         nghttp2_option_set_peer_max_concurrent_streams(options, 
                                                        (uint32_t)session->max_stream_count);
-
         /* We need to handle window updates ourself, otherwise we
          * get flooded by nghttp2. */
         nghttp2_option_set_no_auto_window_update(options, 1);
         
-        rv = nghttp2_session_server_new2(&session->ngh2, callbacks,
-                                         session, options);
+        if (APLOGctrace6(c)) {
+            mem = apr_pcalloc(session->pool, sizeof(nghttp2_mem));
+            mem->mem_user_data = session;
+            mem->malloc    = session_malloc;
+            mem->free      = session_free;
+            mem->calloc    = session_calloc;
+            mem->realloc   = session_realloc;
+            
+            rv = nghttp2_session_server_new3(&session->ngh2, callbacks,
+                                             session, options, mem);
+        }
+        else {
+            rv = nghttp2_session_server_new2(&session->ngh2, callbacks,
+                                             session, options);
+        }
         nghttp2_session_callbacks_del(callbacks);
         nghttp2_option_del(options);
         
@@ -624,141 +890,56 @@ static h2_session *h2_session_create_int(conn_rec *c,
             h2_session_destroy(session);
             return NULL;
         }
+         
+        n = h2_config_geti(session->config, H2_CONF_PUSH_DIARY_SIZE);
+        session->push_diary = h2_push_diary_create(session->pool, n);
         
+        if (APLOGcdebug(c)) {
+            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c,
+                          "session(%ld) created, timeout=%d, keepalive_timeout=%d, "
+                          "max_streams=%d, stream_mem=%d, push_diary(type=%d,N=%d)",
+                          session->id, session->timeout_secs, session->keepalive_secs,
+                          (int)session->max_stream_count, (int)session->max_stream_mem,
+                          session->push_diary->dtype,
+                          (int)session->push_diary->N);
+        }
     }
     return session;
 }
 
-h2_session *h2_session_create(conn_rec *c, h2_config *config, 
-                              h2_workers *workers)
-{
-    return h2_session_create_int(c, NULL, config, workers);
-}
-
-h2_session *h2_session_rcreate(request_rec *r, h2_config *config, 
-                               h2_workers *workers)
-{
-    return h2_session_create_int(r->connection, r, config, workers);
-}
-
-void h2_session_destroy(h2_session *session)
+h2_session *h2_session_create(conn_rec *c, h2_ctx *ctx, h2_workers *workers)
 {
-    AP_DEBUG_ASSERT(session);
-    if (session->mplx) {
-        h2_mplx_release_and_join(session->mplx, session->iowait);
-        session->mplx = NULL;
-    }
-    if (session->streams) {
-        if (h2_stream_set_size(session->streams)) {
-            ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
-                          "h2_session(%ld): destroy, %d streams open",
-                          session->id, (int)h2_stream_set_size(session->streams));
-        }
-        h2_stream_set_destroy(session->streams);
-        session->streams = NULL;
-    }
-    if (session->ngh2) {
-        nghttp2_session_del(session->ngh2);
-        session->ngh2 = NULL;
-    }
-    h2_conn_io_destroy(&session->io);
-    
-    if (session->iowait) {
-        apr_thread_cond_destroy(session->iowait);
-        session->iowait = NULL;
-    }
-    
-    if (session->pool) {
-        apr_pool_destroy(session->pool);
-    }
+    return h2_session_create_int(c, NULL, ctx, workers);
 }
 
-static apr_status_t h2_session_abort_int(h2_session *session, int reason)
+h2_session *h2_session_rcreate(request_rec *r, h2_ctx *ctx, h2_workers *workers)
 {
-    AP_DEBUG_ASSERT(session);
-    if (!session->aborted) {
-        session->aborted = 1;
-        if (session->ngh2) {
-            
-            if (!reason) {
-                nghttp2_submit_goaway(session->ngh2, NGHTTP2_FLAG_NONE, 
-                                      session->max_stream_received, 
-                                      reason, NULL, 0);
-                nghttp2_session_send(session->ngh2);
-                h2_conn_io_flush(&session->io);
-            }
-            else {
-                const char *err = nghttp2_strerror(reason);
-                
-                ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                              "session(%ld): aborting session, reason=%d %s",
-                              session->id, reason, err);
-                
-                if (NGHTTP2_ERR_EOF == reason) {
-                    /* This is our way of indication that the connection is
-                     * gone. No use to send any GOAWAY frames. */
-                    nghttp2_session_terminate_session(session->ngh2, reason);
-                }
-                else {
-                    /* The connection might still be there and we shut down
-                     * with GOAWAY and reason information. */
-                     nghttp2_submit_goaway(session->ngh2, NGHTTP2_FLAG_NONE, 
-                                           session->max_stream_received, 
-                                           reason, (const uint8_t *)err, 
-                                           strlen(err));
-                     nghttp2_session_send(session->ngh2);
-                     h2_conn_io_flush(&session->io);
-                }
-            }
-        }
-        h2_mplx_abort(session->mplx);
-    }
-    return APR_SUCCESS;
+    return h2_session_create_int(r->connection, r, ctx, workers);
 }
 
-apr_status_t h2_session_abort(h2_session *session, apr_status_t reason, int rv)
+void h2_session_eoc_callback(h2_session *session)
 {
-    AP_DEBUG_ASSERT(session);
-    if (rv == 0) {
-        rv = NGHTTP2_ERR_PROTO;
-        switch (reason) {
-            case APR_ENOMEM:
-                rv = NGHTTP2_ERR_NOMEM;
-                break;
-            case APR_SUCCESS:                            /* all fine, just... */
-            case APR_EOF:                         /* client closed its end... */
-            case APR_TIMEUP:                          /* got bored waiting... */
-                rv = 0;                            /* ...gracefully shut down */
-                break;
-            case APR_EBADF:        /* connection unusable, terminate silently */
-            case APR_ECONNABORTED:
-                rv = NGHTTP2_ERR_EOF;
-                break;
-            default:
-                break;
-        }
-    }
-    return h2_session_abort_int(session, rv);
+    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                  "session(%ld): cleanup and destroy", session->id);
+    apr_pool_cleanup_kill(session->pool, session, session_pool_cleanup);
+    h2_session_destroy(session);
 }
 
-apr_status_t h2_session_start(h2_session *session, int *rv)
+static apr_status_t h2_session_start(h2_session *session, int *rv)
 {
     apr_status_t status = APR_SUCCESS;
-    h2_config *config;
     nghttp2_settings_entry settings[3];
+    size_t slen;
+    int win_size;
     
     AP_DEBUG_ASSERT(session);
     /* Start the conversation by submitting our SETTINGS frame */
     *rv = 0;
-    config = h2_config_get(session->c);
     if (session->r) {
         const char *s, *cs;
         apr_size_t dlen; 
         h2_stream * stream;
 
-        /* better for vhost matching */
-        config = h2_config_rget(session->r);
-        
         /* 'h2c' mode: we should have a 'HTTP2-Settings' header with
          * base64 encoded client settings. */
         s = apr_table_get(session->r->headers_in, "HTTP2-Settings");
@@ -789,8 +970,8 @@ apr_status_t h2_session_start(h2_session *session, int *rv)
         }
         
         /* Now we need to auto-open stream 1 for the request we got. */
-        *rv = stream_open(session, 1);
-        if (*rv != 0) {
+        stream = h2_session_open_stream(session, 1);
+        if (!stream) {
             status = APR_EGENERAL;
             ap_log_rerror(APLOG_MARK, APLOG_ERR, status, session->r,
                           APLOGNO(02933) "open stream 1: %s", 
@@ -798,62 +979,75 @@ apr_status_t h2_session_start(h2_session *session, int *rv)
             return status;
         }
         
-        stream = h2_stream_set_get(session->streams, 1);
-        if (stream == NULL) {
-            status = APR_EGENERAL;
-            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, session->r,
-                          APLOGNO(02934) "lookup of stream 1");
-            return status;
-        }
-        
-        status = h2_stream_rwrite(stream, session->r);
+        status = h2_stream_set_request(stream, session->r);
         if (status != APR_SUCCESS) {
             return status;
         }
-        status = stream_end_headers(session, stream, 1);
+        status = stream_schedule(session, stream, 1);
         if (status != APR_SUCCESS) {
             return status;
         }
     }
 
-    settings[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
-    settings[0].value = (uint32_t)session->max_stream_count;
-    settings[1].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
-    settings[1].value = h2_config_geti(config, H2_CONF_WIN_SIZE);
-    settings[2].settings_id = NGHTTP2_SETTINGS_MAX_HEADER_LIST_SIZE;
-    settings[2].value = 64*1024;
+    slen = 0;
+    settings[slen].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
+    settings[slen].value = (uint32_t)session->max_stream_count;
+    ++slen;
+    win_size = h2_config_geti(session->config, H2_CONF_WIN_SIZE);
+    if (win_size != H2_INITIAL_WINDOW_SIZE) {
+        settings[slen].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
+        settings[slen].value = win_size;
+        ++slen;
+    }
     
+    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, session->c,
+                  "h2_session(%ld): start, INITIAL_WINDOW_SIZE=%ld, "
+                  "MAX_CONCURRENT_STREAMS=%d", 
+                  session->id, (long)win_size, (int)session->max_stream_count);
     *rv = nghttp2_submit_settings(session->ngh2, NGHTTP2_FLAG_NONE,
-                                 settings,
-                                 sizeof(settings)/sizeof(settings[0]));
+                                  settings, slen);
     if (*rv != 0) {
         status = APR_EGENERAL;
         ap_log_cerror(APLOG_MARK, APLOG_ERR, status, session->c,
                       APLOGNO(02935) "nghttp2_submit_settings: %s", 
                       nghttp2_strerror(*rv));
     }
-    
+    else {
+        /* use maximum possible value for connection window size. We are only
+         * interested in per stream flow control. which have the initial window
+         * size configured above.
+         * Therefore, for our use, the connection window can only get in the
+         * way. Example: if we allow 100 streams with a 32KB window each, we
+         * buffer up to 3.2 MB of data. Unless we do separate connection window
+         * interim updates, any smaller connection window will lead to blocking
+         * in DATA flow.
+         */
+        *rv = nghttp2_submit_window_update(session->ngh2, NGHTTP2_FLAG_NONE,
+                                           0, NGHTTP2_MAX_WINDOW_SIZE - win_size);
+        if (*rv != 0) {
+            status = APR_EGENERAL;
+            ap_log_cerror(APLOG_MARK, APLOG_ERR, status, session->c,
+                          APLOGNO(02970) "nghttp2_submit_window_update: %s", 
+                          nghttp2_strerror(*rv));        
+        }
+    }
     return status;
 }
 
-static int h2_session_want_write(h2_session *session)
-{
-    return nghttp2_session_want_write(session->ngh2);
-}
-
 typedef struct {
     h2_session *session;
     int resume_count;
 } resume_ctx;
 
-static int resume_on_data(void *ctx, h2_stream *stream) {
+static int resume_on_data(void *ctx, h2_stream *stream)
+{
     resume_ctx *rctx = (resume_ctx*)ctx;
     h2_session *session = rctx->session;
     AP_DEBUG_ASSERT(session);
     AP_DEBUG_ASSERT(stream);
     
     if (h2_stream_is_suspended(stream)) {
-        if (h2_mplx_out_has_data_for(stream->m, stream->id)) {
+        if (h2_mplx_out_has_data_for(stream->session->mplx, stream->id)) {
             int rv;
             h2_stream_set_suspended(stream, 0);
             ++rctx->resume_count;
@@ -862,17 +1056,18 @@ static int resume_on_data(void *ctx, h2_stream *stream) {
             ap_log_cerror(APLOG_MARK, nghttp2_is_fatal(rv)?
                           APLOG_ERR : APLOG_DEBUG, 0, session->c,
                           APLOGNO(02936) 
-                          "h2_stream(%ld-%d): resuming stream %s",
-                          session->id, stream->id, nghttp2_strerror(rv));
+                          "h2_stream(%ld-%d): resuming %s",
+                          session->id, stream->id, rv? nghttp2_strerror(rv) : "");
         }
     }
     return 1;
 }
 
-static int h2_session_resume_streams_with_data(h2_session *session) {
+static int h2_session_resume_streams_with_data(h2_session *session)
+{
     AP_DEBUG_ASSERT(session);
     if (!h2_stream_set_is_empty(session->streams)
-        && session->mplx && !session->aborted) {
+        && session->mplx && !session->mplx->aborted) {
         resume_ctx ctx;
         
         ctx.session      = session;
@@ -886,144 +1081,14 @@ static int h2_session_resume_streams_with_data(h2_session *session) {
     return 0;
 }
 
-static void update_window(void *ctx, int stream_id, apr_size_t bytes_read)
-{
-    h2_session *session = (h2_session*)ctx;
-    nghttp2_session_consume(session->ngh2, stream_id, bytes_read);
-}
-
-static apr_status_t h2_session_update_windows(h2_session *session)
-{
-    return h2_mplx_in_update_windows(session->mplx, update_window, session);
-}
-
-apr_status_t h2_session_write(h2_session *session, apr_interval_time_t timeout)
-{
-    apr_status_t status = APR_EAGAIN;
-    h2_stream *stream = NULL;
-    int flush_output = 0;
-    
-    AP_DEBUG_ASSERT(session);
-    
-    /* Check that any pending window updates are sent. */
-    status = h2_session_update_windows(session);
-    if (status == APR_SUCCESS) {
-        flush_output = 1;
-    }
-    else if (status != APR_EAGAIN) {
-        return status;
-    }
-    
-    if (h2_session_want_write(session)) {
-        int rv;
-        status = APR_SUCCESS;
-        rv = nghttp2_session_send(session->ngh2);
-        if (rv != 0) {
-            ap_log_cerror( APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                          "h2_session: send: %s", nghttp2_strerror(rv));
-            if (nghttp2_is_fatal(rv)) {
-                h2_session_abort_int(session, rv);
-                status = APR_ECONNABORTED;
-            }
-        }
-        flush_output = 1;
-    }
-    
-    /* If we have responses ready, submit them now. */
-    while ((stream = h2_mplx_next_submit(session->mplx, 
-                                         session->streams)) != NULL) {
-        status = h2_session_handle_response(session, stream);
-        flush_output = 1;
-    }
-    
-    if (h2_session_resume_streams_with_data(session) > 0) {
-        flush_output = 1;
-    }
-    
-    if (!flush_output && timeout > 0 && !h2_session_want_write(session)) {
-        status = h2_mplx_out_trywait(session->mplx, timeout, session->iowait);
-
-        if (status != APR_TIMEUP
-            && h2_session_resume_streams_with_data(session) > 0) {
-            flush_output = 1;
-        }
-        else {
-            /* nothing happened to ongoing streams, do some house-keeping */
-        }
-    }
-    
-    if (h2_session_want_write(session)) {
-        int rv;
-        status = APR_SUCCESS;
-        rv = nghttp2_session_send(session->ngh2);
-        if (rv != 0) {
-            ap_log_cerror( APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                          "h2_session: send2: %s", nghttp2_strerror(rv));
-            if (nghttp2_is_fatal(rv)) {
-                h2_session_abort_int(session, rv);
-                status = APR_ECONNABORTED;
-            }
-        }
-        flush_output = 1;
-    }
-    
-    if (flush_output) {
-        h2_conn_io_flush(&session->io);
-    }
-    
-    return status;
-}
-
 h2_stream *h2_session_get_stream(h2_session *session, int stream_id)
 {
-    AP_DEBUG_ASSERT(session);
-    return h2_stream_set_get(session->streams, stream_id);
-}
-
-/* h2_io_on_read_cb implementation that offers the data read
- * directly to the session for consumption.
- */
-static apr_status_t session_receive(const char *data, apr_size_t len,
-                                    apr_size_t *readlen, int *done,
-                                    void *puser)
-{
-    h2_session *session = (h2_session *)puser;
-    AP_DEBUG_ASSERT(session);
-    if (len > 0) {
-        ssize_t n = nghttp2_session_mem_recv(session->ngh2,
-                                             (const uint8_t *)data, len);
-        if (n < 0) {
-            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, APR_EGENERAL,
-                          session->c,
-                          "h2_session: nghttp2_session_mem_recv error %d",
-                          (int)n);
-            if (nghttp2_is_fatal((int)n)) {
-                *done = 1;
-                h2_session_abort_int(session, (int)n);
-                return APR_EGENERAL;
-            }
-        }
-        else {
-            *readlen = n;
-        }
+    if (!session->last_stream || stream_id != session->last_stream->id) {
+        session->last_stream = h2_stream_set_get(session->streams, stream_id);
     }
-    return APR_SUCCESS;
+    return session->last_stream;
 }
 
-apr_status_t h2_session_read(h2_session *session, apr_read_type_e block)
-{
-    AP_DEBUG_ASSERT(session);
-    return h2_conn_io_read(&session->io, block, session_receive, session);
-}
-
-apr_status_t h2_session_close(h2_session *session)
-{
-    AP_DEBUG_ASSERT(session);
-    return session->aborted? APR_SUCCESS : h2_conn_io_flush(&session->io);
-}
-
-/* The session wants to send more DATA for the given stream.
- */
 static ssize_t stream_data_cb(nghttp2_session *ng2s,
                               int32_t stream_id,
                               uint8_t *buf,
@@ -1033,18 +1098,25 @@ static ssize_t stream_data_cb(nghttp2_session *ng2s,
                               void *puser)
 {
     h2_session *session = (h2_session *)puser;
-    apr_size_t nread = length;
+    apr_off_t nread = length;
     int eos = 0;
     apr_status_t status;
     h2_stream *stream;
     AP_DEBUG_ASSERT(session);
     
+    /* The session wants to send more DATA for the stream. We need
+     * to find out how much of the requested length we can send without
+     * blocking.
+     * Indicate EOS when we encounter it or DEFERRED if the stream
+     * should be suspended. Beware of trailers.
+     */
     (void)ng2s;
     (void)buf;
     (void)source;
-    stream = h2_stream_set_get(session->streams, stream_id);
+    stream = h2_session_get_stream(session, stream_id);
     if (!stream) {
-        ap_log_cerror(APLOG_MARK, APLOG_ERR, APR_NOTFOUND, session->c,
+        ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c,
                       APLOGNO(02937) 
                       "h2_stream(%ld-%d): data requested but stream not found",
                       session->id, (int)stream_id);
@@ -1062,6 +1134,10 @@ static ssize_t stream_data_cb(nghttp2_session *ng2s,
         case APR_SUCCESS:
             break;
             
+        case APR_ECONNRESET:
+            return nghttp2_submit_rst_stream(ng2s, NGHTTP2_FLAG_NONE,
+                stream->id, stream->rst_error);
+            
         case APR_EAGAIN:
             /* If there is no data available, our session will automatically
              * suspend this stream and not ask for more data until we resume
@@ -1070,7 +1146,7 @@ static ssize_t stream_data_cb(nghttp2_session *ng2s,
             nread = 0;
             h2_stream_set_suspended(stream, 1);
             ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                          "h2_stream(%ld-%d): suspending stream",
+                          "h2_stream(%ld-%d): suspending",
                           session->id, (int)stream_id);
             return NGHTTP2_ERR_DEFERRED;
             
@@ -1088,6 +1164,22 @@ static ssize_t stream_data_cb(nghttp2_session *ng2s,
     }
     
     if (eos) {
+        apr_table_t *trailers = h2_stream_get_trailers(stream);
+        if (trailers && !apr_is_empty_table(trailers)) {
+            h2_ngheader *nh;
+            int rv;
+            
+            nh = h2_util_ngheader_make(stream->pool, trailers);
+            ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                          "h2_stream(%ld-%d): submit %d trailers",
+                          session->id, (int)stream_id,(int) nh->nvlen);
+            rv = nghttp2_submit_trailer(ng2s, stream->id, nh->nv, nh->nvlen);
+            if (rv < 0) {
+                nread = rv;
+            }
+            *data_flags |= NGHTTP2_DATA_FLAG_NO_END_STREAM;
+        }
+        
         *data_flags |= NGHTTP2_DATA_FLAG_EOF;
     }
     
@@ -1100,95 +1192,280 @@ typedef struct {
     size_t offset;
 } nvctx_t;
 
-static int submit_response(h2_session *session, h2_response *response)
-{
-    nghttp2_data_provider provider;
-    int rv;
-    
-    memset(&provider, 0, sizeof(provider));
-    provider.source.fd = response->stream_id;
-    provider.read_callback = stream_data_cb;
-    
-    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
-                  "h2_stream(%ld-%d): submitting response %s",
-                  session->id, response->stream_id, response->status);
-    
-    rv = nghttp2_submit_response(session->ngh2, response->stream_id,
-                                 response->ngheader->nv, 
-                                 response->ngheader->nvlen, &provider);
-    
-    if (rv != 0) {
-        ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, session->c,
-                      APLOGNO(02939) "h2_stream(%ld-%d): submit_response: %s",
-                      session->id, response->stream_id, nghttp2_strerror(rv));
-    }
-    else {
-        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
-                      "h2_stream(%ld-%d): submitted response %s, rv=%d",
-                      session->id, response->stream_id, 
-                      response->status, rv);
-    }
-    return rv;
-}
-
-/* Start submitting the response to a stream request. This is possible
+/**
+ * Start submitting the response to a stream request. This is possible
  * once we have all the response headers. The response body will be
  * read by the session using the callback we supply.
  */
-apr_status_t h2_session_handle_response(h2_session *session, h2_stream *stream)
+static apr_status_t submit_response(h2_session *session, h2_stream *stream)
 {
     apr_status_t status = APR_SUCCESS;
+    h2_response *response = h2_stream_get_response(stream);
     int rv = 0;
     AP_DEBUG_ASSERT(session);
     AP_DEBUG_ASSERT(stream);
-    AP_DEBUG_ASSERT(stream->response);
+    AP_DEBUG_ASSERT(response || stream->rst_error);
     
-    if (stream->response->ngheader) {
-        rv = submit_response(session, stream->response);
+    if (stream->submitted) {
+        rv = NGHTTP2_PROTOCOL_ERROR;
+    }
+    else if (response && response->headers) {
+        nghttp2_data_provider provider;
+        h2_ngheader *ngh;
+        const h2_priority *prio;
+        
+        memset(&provider, 0, sizeof(provider));
+        provider.source.fd = stream->id;
+        provider.read_callback = stream_data_cb;
+        
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_stream(%ld-%d): submit response %d",
+                      session->id, stream->id, response->http_status);
+        
+        /* If this stream is not a pushed one itself,
+         * and HTTP/2 server push is enabled here,
+         * and the response is in the range 200-299 *),
+         * and the remote side has pushing enabled,
+         * -> find and perform any pushes on this stream
+         *    *before* we submit the stream response itself.
+         *    This helps clients avoid opening new streams on Link
+         *    headers that get pushed right afterwards.
+         * 
+         * *) the response code is relevant, as we do not want to 
+         *    make pushes on 401 or 403 codes, neiterh on 301/302
+         *    and friends. And if we see a 304, we do not push either
+         *    as the client, having this resource in its cache, might
+         *    also have the pushed ones as well.
+         */
+        if (!stream->initiated_on
+            && H2_HTTP_2XX(response->http_status)
+            && h2_session_push_enabled(session)) {
+            
+            h2_stream_submit_pushes(stream);
+        }
+        
+        prio = h2_stream_get_priority(stream);
+        if (prio) {
+            h2_session_set_prio(session, stream, prio);
+            /* no showstopper if that fails for some reason */
+        }
+        
+        ngh = h2_util_ngheader_make_res(stream->pool, response->http_status, 
+                                        response->headers);
+        rv = nghttp2_submit_response(session->ngh2, response->stream_id,
+                                     ngh->nv, ngh->nvlen, &provider);
     }
     else {
+        int err = H2_STREAM_RST(stream, H2_ERR_PROTOCOL_ERROR);
+        
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_stream(%ld-%d): RST_STREAM, err=%d",
+                      session->id, stream->id, err);
+
         rv = nghttp2_submit_rst_stream(session->ngh2, NGHTTP2_FLAG_NONE,
-                                       stream->id, NGHTTP2_PROTOCOL_ERROR);
+                                       stream->id, err);
     }
     
+    stream->submitted = 1;
+    if (stream->initiated_on) {
+        ++session->pushes_submitted;
+    }
+    else {
+        ++session->responses_submitted;
+    }
+
     if (nghttp2_is_fatal(rv)) {
         status = APR_EGENERAL;
-        h2_session_abort_int(session, rv);
+        dispatch_event(session, H2_SESSION_EV_PROTO_ERROR, rv, nghttp2_strerror(rv));
         ap_log_cerror(APLOG_MARK, APLOG_ERR, status, session->c,
                       APLOGNO(02940) "submit_response: %s", 
                       nghttp2_strerror(rv));
     }
+    
     return status;
 }
 
-int h2_session_is_done(h2_session *session)
-{
-    AP_DEBUG_ASSERT(session);
-    return (session->aborted
-            || !session->ngh2
-            || (!nghttp2_session_want_read(session->ngh2)
-                && !nghttp2_session_want_write(session->ngh2)));
-}
-
-static int log_stream(void *ctx, h2_stream *stream)
-{
-    h2_session *session = (h2_session *)ctx;
-    AP_DEBUG_ASSERT(session);
-    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
-                  "h2_stream(%ld-%d): in set, suspended=%d, aborted=%d, "
-                  "has_data=%d",
-                  session->id, stream->id, stream->suspended, stream->aborted,
-                  h2_mplx_out_has_data_for(session->mplx, stream->id));
-    return 1;
-}
-
-void h2_session_log_stats(h2_session *session)
+struct h2_stream *h2_session_push(h2_session *session, h2_stream *is,
+                                  h2_push *push)
 {
-    AP_DEBUG_ASSERT(session);
-    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
-                  "h2_session(%ld): %d open streams",
-                  session->id, (int)h2_stream_set_size(session->streams));
-    h2_stream_set_iter(session->streams, log_stream, session);
+    apr_status_t status;
+    h2_stream *stream;
+    h2_ngheader *ngh;
+    int nid;
+    
+    ngh = h2_util_ngheader_make_req(is->pool, push->req);
+    nid = nghttp2_submit_push_promise(session->ngh2, 0, is->id, 
+                                      ngh->nv, ngh->nvlen, NULL);
+    if (nid <= 0) {
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_stream(%ld-%d): submitting push promise fail: %s",
+                      session->id, is->id, nghttp2_strerror(nid));
+        return NULL;
+    }
+    ++session->pushes_promised;
+    
+    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                  "h2_stream(%ld-%d): SERVER_PUSH %d for %s %s on %d",
+                  session->id, is->id, nid,
+                  push->req->method, push->req->path, is->id);
+                  
+    stream = h2_session_open_stream(session, nid);
+    if (stream) {
+        h2_stream_set_h2_request(stream, is->id, push->req);
+        status = stream_schedule(session, stream, 1);
+        if (status != APR_SUCCESS) {
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, status, session->c,
+                          "h2_stream(%ld-%d): scheduling push stream",
+                          session->id, stream->id);
+            h2_stream_cleanup(stream);
+            stream = NULL;
+        }
+        ++session->unsent_promises;
+    }
+    else {
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_stream(%ld-%d): failed to create stream obj %d",
+                      session->id, is->id, nid);
+    }
+
+    if (!stream) {
+        /* try to tell the client that it should not wait. */
+        nghttp2_submit_rst_stream(session->ngh2, NGHTTP2_FLAG_NONE, nid,
+                                  NGHTTP2_INTERNAL_ERROR);
+    }
+    
+    return stream;
+}
+
+static int valid_weight(float f) 
+{
+    int w = (int)f;
+    return (w < NGHTTP2_MIN_WEIGHT? NGHTTP2_MIN_WEIGHT : 
+            (w > NGHTTP2_MAX_WEIGHT)? NGHTTP2_MAX_WEIGHT : w);
+}
+
+apr_status_t h2_session_set_prio(h2_session *session, h2_stream *stream, 
+                                 const h2_priority *prio)
+{
+    apr_status_t status = APR_SUCCESS;
+#ifdef H2_NG2_CHANGE_PRIO
+    nghttp2_stream *s_grandpa, *s_parent, *s;
+    
+    s = nghttp2_session_find_stream(session->ngh2, stream->id);
+    if (!s) {
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                      "h2_stream(%ld-%d): lookup of nghttp2_stream failed",
+                      session->id, stream->id);
+        return APR_EINVAL;
+    }
+    
+    s_parent = nghttp2_stream_get_parent(s);
+    if (s_parent) {
+        nghttp2_priority_spec ps;
+        int id_parent, id_grandpa, w_parent, w, rv = 0;
+        char *ptype = "AFTER";
+        h2_dependency dep = prio->dependency;
+        
+        id_parent = nghttp2_stream_get_stream_id(s_parent);
+        s_grandpa = nghttp2_stream_get_parent(s_parent);
+        if (s_grandpa) {
+            id_grandpa = nghttp2_stream_get_stream_id(s_grandpa);
+        }
+        else {
+            /* parent of parent does not exist, 
+             * only possible if parent == root */
+            dep = H2_DEPENDANT_AFTER;
+        }
+        
+        switch (dep) {
+            case H2_DEPENDANT_INTERLEAVED:
+                /* PUSHed stream is to be interleaved with initiating stream.
+                 * It is made a sibling of the initiating stream and gets a
+                 * proportional weight [1, MAX_WEIGHT] of the initiaing
+                 * stream weight.
+                 */
+                ptype = "INTERLEAVED";
+                w_parent = nghttp2_stream_get_weight(s_parent);
+                w = valid_weight(w_parent * ((float)prio->weight / NGHTTP2_MAX_WEIGHT));
+                nghttp2_priority_spec_init(&ps, id_grandpa, w, 0);
+                break;
+                
+            case H2_DEPENDANT_BEFORE:
+                /* PUSHed stream os to be sent BEFORE the initiating stream.
+                 * It gets the same weight as the initiating stream, replaces
+                 * that stream in the dependency tree and has the initiating
+                 * stream as child.
+                 */
+                ptype = "BEFORE";
+                w = w_parent = nghttp2_stream_get_weight(s_parent);
+                nghttp2_priority_spec_init(&ps, stream->id, w_parent, 0);
+                id_grandpa = nghttp2_stream_get_stream_id(s_grandpa);
+                rv = nghttp2_session_change_stream_priority(session->ngh2, id_parent, &ps);
+                if (rv < 0) {
+                    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                                  "h2_stream(%ld-%d): PUSH BEFORE, weight=%d, "
+                                  "depends=%d, returned=%d",
+                                  session->id, id_parent, ps.weight, ps.stream_id, rv);
+                    return APR_EGENERAL;
+                }
+                nghttp2_priority_spec_init(&ps, id_grandpa, w, 0);
+                break;
+                
+            case H2_DEPENDANT_AFTER:
+                /* The PUSHed stream is to be sent after the initiating stream.
+                 * Give if the specified weight and let it depend on the intiating
+                 * stream.
+                 */
+                /* fall through, it's the default */
+            default:
+                nghttp2_priority_spec_init(&ps, id_parent, valid_weight(prio->weight), 0);
+                break;
+        }
+
+
+        rv = nghttp2_session_change_stream_priority(session->ngh2, stream->id, &ps);
+        ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                      "h2_stream(%ld-%d): PUSH %s, weight=%d, "
+                      "depends=%d, returned=%d",
+                      session->id, stream->id, ptype, 
+                      ps.weight, ps.stream_id, rv);
+        status = (rv < 0)? APR_EGENERAL : APR_SUCCESS;
+    }
+#else
+    (void)session;
+    (void)stream;
+    (void)prio;
+    (void)valid_weight;
+#endif
+    return status;
+}
+
+apr_status_t h2_session_stream_destroy(h2_session *session, h2_stream *stream)
+{
+    apr_pool_t *pool = h2_stream_detach_pool(stream);
+
+    /* this may be called while the session has already freed
+     * some internal structures. */
+    if (session->mplx) {
+        h2_mplx_stream_done(session->mplx, stream->id, stream->rst_error);
+        if (session->last_stream == stream) {
+            session->last_stream = NULL;
+        }
+    }
+    
+    if (session->streams) {
+        h2_stream_set_remove(session->streams, stream->id);
+    }
+    h2_stream_destroy(stream);
+    
+    if (pool) {
+        apr_pool_clear(pool);
+        if (session->spare) {
+            apr_pool_destroy(session->spare);
+        }
+        session->spare = pool;
+    }
+    return APR_SUCCESS;
 }
 
 static int frame_print(const nghttp2_frame *frame, char *buffer, size_t maxlen)
@@ -1262,9 +1539,605 @@ static int frame_print(const nghttp2_frame *frame, char *buffer, size_t maxlen)
         }
         default:
             return apr_snprintf(buffer, maxlen,
-                                "FRAME[type=%d, length=%d, flags=%d, stream=%d]",
+                                "type=%d[length=%d, flags=%d, stream=%d]",
                                 frame->hd.type, (int)frame->hd.length,
                                 frame->hd.flags, frame->hd.stream_id);
     }
 }
 
+int h2_session_push_enabled(h2_session *session)
+{
+    /* iff we can and they can */
+    return (h2_config_geti(session->config, H2_CONF_PUSH)
+            && nghttp2_session_get_remote_settings(session->ngh2, 
+                                                   NGHTTP2_SETTINGS_ENABLE_PUSH));
+}
+
+static apr_status_t h2_session_send(h2_session *session)
+{
+    int rv = nghttp2_session_send(session->ngh2);
+    if (rv != 0) {
+        if (nghttp2_is_fatal(rv)) {
+            dispatch_event(session, H2_SESSION_EV_PROTO_ERROR, rv, nghttp2_strerror(rv));
+            return APR_EGENERAL;
+        }
+    }
+    
+    session->unsent_promises = 0;
+    session->unsent_submits = 0;
+    
+    return APR_SUCCESS;
+}
+
+static apr_status_t h2_session_receive(void *ctx, const char *data, 
+                                       apr_size_t len, apr_size_t *readlen)
+{
+    h2_session *session = ctx;
+    ssize_t n;
+    
+    if (len > 0) {
+        ap_log_cerror(APLOG_MARK, APLOG_TRACE2, 0, session->c,
+                      "h2_session(%ld): feeding %ld bytes to nghttp2",
+                      session->id, (long)len);
+        n = nghttp2_session_mem_recv(session->ngh2, (const uint8_t *)data, len);
+        if (n < 0) {
+            if (nghttp2_is_fatal((int)n)) {
+                dispatch_event(session, H2_SESSION_EV_PROTO_ERROR, (int)n, nghttp2_strerror(n));
+                return APR_EGENERAL;
+            }
+        }
+        else {
+            *readlen = n;
+            session->io.bytes_read += n;
+        }
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t h2_session_read(h2_session *session, int block, int loops)
+{
+    apr_status_t status, rstatus = APR_EAGAIN;
+    conn_rec *c = session->c;
+    int i;
+    
+    for (i = 0; i < loops; ++i) {
+        /* H2_IN filter handles all incoming data against the session.
+         * We just pull at the filter chain to make it happen */
+        status = ap_get_brigade(c->input_filters,
+                                session->bbtmp, AP_MODE_READBYTES,
+                                block? APR_BLOCK_READ : APR_NONBLOCK_READ,
+                                APR_BUCKET_BUFF_SIZE);
+        /* get rid of any possible data we do not expect to get */
+        apr_brigade_cleanup(session->bbtmp); 
+
+        switch (status) {
+            case APR_SUCCESS:
+                /* successful read, reset our idle timers */
+                rstatus = APR_SUCCESS;
+                if (block) {
+                    /* successfull blocked read, try unblocked to
+                     * get more. */
+                    block = 0;
+                }
+                break;
+            case APR_EAGAIN:
+                return rstatus;
+            case APR_TIMEUP:
+                return status;
+            default:
+                if (!i) {
+                    /* first attempt failed */
+                    if (APR_STATUS_IS_ETIMEDOUT(status)
+                        || APR_STATUS_IS_ECONNABORTED(status)
+                        || APR_STATUS_IS_ECONNRESET(status)
+                        || APR_STATUS_IS_EOF(status)
+                        || APR_STATUS_IS_EBADF(status)) {
+                        /* common status for a client that has left */
+                        ap_log_cerror( APLOG_MARK, APLOG_TRACE1, status, c,
+                                      "h2_session(%ld): input gone", session->id);
+                    }
+                    else {
+                        /* uncommon status, log on INFO so that we see this */
+                        ap_log_cerror( APLOG_MARK, APLOG_INFO, status, c,
+                                      APLOGNO(02950) 
+                                      "h2_session(%ld): error reading, terminating",
+                                      session->id);
+                    }
+                    return status;
+                }
+                /* subsequent failure after success(es), return initial
+                 * status. */
+                return rstatus;
+        }
+        if (!is_accepting_streams(session)) {
+            break;
+        }
+    }
+    return rstatus;
+}
+
+static apr_status_t h2_session_submit(h2_session *session)
+{
+    apr_status_t status = APR_EAGAIN;
+    h2_stream *stream;
+    
+    if (h2_stream_set_has_unsubmitted(session->streams)) {
+        /* If we have responses ready, submit them now. */
+        while ((stream = h2_mplx_next_submit(session->mplx, session->streams))) {
+            status = submit_response(session, stream);
+            ++session->unsent_submits;
+            
+            /* Unsent push promises are written immediately, as nghttp2
+             * 1.5.0 realizes internal stream data structures only on 
+             * send and we might need them for other submits. 
+             * Also, to conserve memory, we send at least every 10 submits
+             * so that nghttp2 does not buffer all outbound items too 
+             * long.
+             */
+            if (status == APR_SUCCESS 
+                && (session->unsent_promises || session->unsent_submits > 10)) {
+                status = h2_session_send(session);
+                if (status != APR_SUCCESS) {
+                    break;
+                }
+            }
+        }
+    }
+    return status;
+}
+
+static const char *StateNames[] = {
+    "INIT",      /* H2_SESSION_ST_INIT */
+    "DONE",      /* H2_SESSION_ST_DONE */
+    "IDLE",      /* H2_SESSION_ST_IDLE */
+    "BUSY",      /* H2_SESSION_ST_BUSY */
+    "WAIT",      /* H2_SESSION_ST_WAIT */
+    "LSHUTDOWN", /* H2_SESSION_ST_LOCAL_SHUTDOWN */
+    "RSHUTDOWN", /* H2_SESSION_ST_REMOTE_SHUTDOWN */
+};
+
+static const char *state_name(h2_session_state state)
+{
+    if (state >= (sizeof(StateNames)/sizeof(StateNames[0]))) {
+        return "unknown";
+    }
+    return StateNames[state];
+}
+
+static int is_accepting_streams(h2_session *session)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_IDLE:
+        case H2_SESSION_ST_BUSY:
+        case H2_SESSION_ST_WAIT:
+            return 1;
+        default:
+            return 0;
+    }
+}
+
+static void transit(h2_session *session, const char *action, h2_session_state nstate)
+{
+    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, session->c,
+                  "h2_session(%ld): transit [%s] -- %s --> [%s]", session->id,
+                  state_name(session->state), action, state_name(nstate));
+    session->state = nstate;
+}
+
+static void h2_session_ev_init(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_INIT:
+            transit(session, "init", H2_SESSION_ST_BUSY);
+            break;
+
+        default:
+            /* nop */
+            break;
+    }
+}
+
+static void h2_session_ev_local_goaway(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_LOCAL_SHUTDOWN:
+            /* already did that? */
+            break;
+        case H2_SESSION_ST_IDLE:
+        case H2_SESSION_ST_REMOTE_SHUTDOWN:
+            /* all done */
+            transit(session, "local goaway", H2_SESSION_ST_DONE);
+            break;
+        default:
+            transit(session, "local goaway", H2_SESSION_ST_LOCAL_SHUTDOWN);
+            break;
+    }
+}
+
+static void h2_session_ev_remote_goaway(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_REMOTE_SHUTDOWN:
+            /* already received that? */
+            break;
+        case H2_SESSION_ST_IDLE:
+        case H2_SESSION_ST_LOCAL_SHUTDOWN:
+            /* all done */
+            transit(session, "remote goaway", H2_SESSION_ST_DONE);
+            break;
+        default:
+            transit(session, "remote goaway", H2_SESSION_ST_REMOTE_SHUTDOWN);
+            break;
+    }
+}
+
+static void h2_session_ev_conn_error(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_INIT:
+        case H2_SESSION_ST_DONE:
+        case H2_SESSION_ST_LOCAL_SHUTDOWN:
+            /* just leave */
+            transit(session, "conn error", H2_SESSION_ST_DONE);
+            break;
+        
+        default:
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                          "h2_session(%ld): conn error -> shutdown", session->id);
+            h2_session_shutdown(session, arg, msg);
+            break;
+    }
+}
+
+static void h2_session_ev_proto_error(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_DONE:
+        case H2_SESSION_ST_LOCAL_SHUTDOWN:
+            /* just leave */
+            transit(session, "proto error", H2_SESSION_ST_DONE);
+            break;
+        
+        default:
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                          "h2_session(%ld): proto error -> shutdown", session->id);
+            h2_session_shutdown(session, arg, msg);
+            break;
+    }
+}
+
+static void h2_session_ev_conn_timeout(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_LOCAL_SHUTDOWN:
+            transit(session, "conn timeout", H2_SESSION_ST_DONE);
+            break;
+        default:
+            h2_session_shutdown(session, arg, msg);
+            transit(session, "conn timeout", H2_SESSION_ST_DONE);
+            break;
+    }
+}
+
+static void h2_session_ev_no_io(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_BUSY:
+            /* nothing for input and output to do. If we remain
+             * in this state, we go into a tight loop and suck up
+             * CPU cycles. Ideally, we'd like to do a blocking read, but that
+             * is not possible if we have scheduled tasks and wait
+             * for them to produce something. */
+            if (h2_stream_set_is_empty(session->streams)) {
+                /* When we have no streams, no task event are possible,
+                 * switch to blocking reads */
+                transit(session, "no io", H2_SESSION_ST_IDLE);
+            }
+            else if (!h2_stream_set_has_unsubmitted(session->streams)
+                     && !h2_stream_set_has_suspended(session->streams)) {
+                /* none of our streams is waiting for a response or
+                 * new output data from task processing, 
+                 * switch to blocking reads. */
+                transit(session, "no io", H2_SESSION_ST_IDLE);
+            }
+            else {
+                /* Unable to do blocking reads, as we wait on events from
+                 * task processing in other threads. Do a busy wait with
+                 * backoff timer. */
+                transit(session, "no io", H2_SESSION_ST_WAIT);
+            }
+            break;
+        default:
+            /* nop */
+            break;
+    }
+}
+
+static void h2_session_ev_wait_timeout(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_WAIT:
+            transit(session, "wait timeout", H2_SESSION_ST_BUSY);
+            break;
+        default:
+            /* nop */
+            break;
+    }
+}
+
+static void h2_session_ev_stream_ready(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_WAIT:
+            transit(session, "stream ready", H2_SESSION_ST_BUSY);
+            break;
+        default:
+            /* nop */
+            break;
+    }
+}
+
+static void h2_session_ev_data_read(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_IDLE:
+            transit(session, "data read", H2_SESSION_ST_BUSY);
+            break;
+            /* fall through */
+        default:
+            /* nop */
+            break;
+    }
+}
+
+static void h2_session_ev_ngh2_done(h2_session *session, int arg, const char *msg)
+{
+    switch (session->state) {
+        case H2_SESSION_ST_DONE:
+            /* nop */
+            break;
+        default:
+            transit(session, "nghttp2 done", H2_SESSION_ST_DONE);
+            break;
+    }
+}
+
+static void dispatch_event(h2_session *session, h2_session_event_t ev, 
+                      int arg, const char *msg)
+{
+    switch (ev) {
+        case H2_SESSION_EV_INIT:
+            h2_session_ev_init(session, arg, msg);
+            break;            
+        case H2_SESSION_EV_LOCAL_GOAWAY:
+            h2_session_ev_local_goaway(session, arg, msg);
+            break;
+        case H2_SESSION_EV_REMOTE_GOAWAY:
+            h2_session_ev_remote_goaway(session, arg, msg);
+            break;
+        case H2_SESSION_EV_CONN_ERROR:
+            h2_session_ev_conn_error(session, arg, msg);
+            break;
+        case H2_SESSION_EV_PROTO_ERROR:
+            h2_session_ev_proto_error(session, arg, msg);
+            break;
+        case H2_SESSION_EV_CONN_TIMEOUT:
+            h2_session_ev_conn_timeout(session, arg, msg);
+            break;
+        case H2_SESSION_EV_NO_IO:
+            h2_session_ev_no_io(session, arg, msg);
+            break;
+        case H2_SESSION_EV_WAIT_TIMEOUT:
+            h2_session_ev_wait_timeout(session, arg, msg);
+            break;
+        case H2_SESSION_EV_STREAM_READY:
+            h2_session_ev_stream_ready(session, arg, msg);
+            break;
+        case H2_SESSION_EV_DATA_READ:
+            h2_session_ev_data_read(session, arg, msg);
+            break;
+        case H2_SESSION_EV_NGH2_DONE:
+            h2_session_ev_ngh2_done(session, arg, msg);
+            break;
+        default:
+            ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, session->c,
+                          "h2_session(%ld): unknown event %d", 
+                          session->id, ev);
+            break;
+    }
+    
+    if (session->state == H2_SESSION_ST_DONE) {
+        h2_mplx_abort(session->mplx);
+    }
+}
+
+static const int MAX_WAIT_MICROS = 200 * 1000;
+
+apr_status_t h2_session_process(h2_session *session, int async)
+{
+    apr_status_t status = APR_SUCCESS;
+    conn_rec *c = session->c;
+    int rv, have_written, have_read;
+
+    ap_log_cerror( APLOG_MARK, APLOG_TRACE1, status, c,
+                  "h2_session(%ld): process start, async=%d", session->id, async);
+                  
+    while (1) {
+        have_read = have_written = 0;
+
+        switch (session->state) {
+            case H2_SESSION_ST_INIT:
+                if (!h2_is_acceptable_connection(c, 1)) {
+                    h2_session_shutdown(session, NGHTTP2_INADEQUATE_SECURITY, NULL);
+                } 
+                else {
+                    ap_update_child_status(c->sbh, SERVER_BUSY_READ, NULL);
+                    status = h2_session_start(session, &rv);
+                    ap_log_cerror(APLOG_MARK, APLOG_DEBUG, status, c,
+                                  "h2_session(%ld): started on %s:%d", session->id,
+                                  session->s->server_hostname,
+                                  c->local_addr->port);
+                    if (status != APR_SUCCESS) {
+                        dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 0, NULL);
+                    }
+                    dispatch_event(session, H2_SESSION_EV_INIT, 0, NULL);
+                }
+                break;
+                
+            case H2_SESSION_ST_IDLE:
+                h2_filter_cin_timeout_set(session->cin, session->keepalive_secs);
+                ap_update_child_status(c->sbh, SERVER_BUSY_KEEPALIVE, NULL);
+                status = h2_session_read(session, 1, 10);
+                if (status == APR_SUCCESS) {
+                    have_read = 1;
+                    dispatch_event(session, H2_SESSION_EV_DATA_READ, 0, NULL);
+                }
+                else if (status == APR_EAGAIN) {
+                    /* nothing to read */
+                }
+                else if (APR_STATUS_IS_TIMEUP(status)) {
+                    dispatch_event(session, H2_SESSION_EV_CONN_TIMEOUT, 0, NULL);
+                    break;
+                }
+                else {
+                    dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 0, NULL);
+                }
+                break;
+                
+            case H2_SESSION_ST_BUSY:
+            case H2_SESSION_ST_LOCAL_SHUTDOWN:
+            case H2_SESSION_ST_REMOTE_SHUTDOWN:
+                if (nghttp2_session_want_read(session->ngh2)) {
+                    ap_update_child_status(c->sbh, SERVER_BUSY_READ, NULL);
+                    h2_filter_cin_timeout_set(session->cin, session->timeout_secs);
+                    status = h2_session_read(session, 0, 10);
+                    if (status == APR_SUCCESS) {
+                        have_read = 1;
+                        dispatch_event(session, H2_SESSION_EV_DATA_READ, 0, NULL);
+                    }
+                    else if (status == APR_EAGAIN) {
+                        /* nothing to read */
+                    }
+                    else if (APR_STATUS_IS_TIMEUP(status)) {
+                        dispatch_event(session, H2_SESSION_EV_CONN_TIMEOUT, 0, NULL);
+                        break;
+                    }
+                    else {
+                        dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 0, NULL);
+                    }
+                }
+                
+                if (!h2_stream_set_is_empty(session->streams)) {
+                    /* resume any streams for which data is available again */
+                    h2_session_resume_streams_with_data(session);
+                    /* Submit any responses/push_promises that are ready */
+                    status = h2_session_submit(session);
+                    if (status == APR_SUCCESS) {
+                        have_written = 1;
+                    }
+                    else if (status != APR_EAGAIN) {
+                        dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 
+                                         H2_ERR_INTERNAL_ERROR, "submit error");
+                        break;
+                    }
+                    /* send out window updates for our inputs */
+                    status = h2_mplx_in_update_windows(session->mplx);
+                    if (status != APR_SUCCESS && status != APR_EAGAIN) {
+                        dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 
+                                         H2_ERR_INTERNAL_ERROR, "window update error");
+                        break;
+                    }
+                }
+                
+                if (nghttp2_session_want_write(session->ngh2)) {
+                    status = h2_session_send(session);
+                    if (status == APR_SUCCESS) {
+                        have_written = 1;
+                    }
+                    else {
+                        dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 
+                                         H2_ERR_INTERNAL_ERROR, "writing");
+                        break;
+                    }
+                }
+                
+                if (have_read || have_written) {
+                    session->wait_us = 0;
+                }
+                else {
+                    dispatch_event(session, H2_SESSION_EV_NO_IO, 0, NULL);
+                }
+                break;
+                
+            case H2_SESSION_ST_WAIT:
+                session->wait_us = H2MAX(session->wait_us, 10);
+                if (APLOGctrace1(c)) {
+                    ap_log_cerror(APLOG_MARK, APLOG_TRACE1, 0, c,
+                                  "h2_session: wait for data, %ld micros", 
+                                  (long)session->wait_us);
+                }
+                
+                ap_log_cerror( APLOG_MARK, APLOG_TRACE2, status, c,
+                              "h2_session(%ld): process -> trywait", session->id);
+                status = h2_mplx_out_trywait(session->mplx, session->wait_us, 
+                                             session->iowait);
+                if (status == APR_SUCCESS) {
+                    dispatch_event(session, H2_SESSION_EV_STREAM_READY, 0, NULL);
+                }
+                else if (status == APR_TIMEUP) {
+                    /* nothing, increase timer for graceful backup */
+                    session->wait_us = H2MIN(session->wait_us*2, MAX_WAIT_MICROS);
+                    dispatch_event(session, H2_SESSION_EV_WAIT_TIMEOUT, 0, NULL);
+                }
+                else {
+                    h2_session_shutdown(session, H2_ERR_INTERNAL_ERROR, "cond wait error");
+                }
+                break;
+                
+            case H2_SESSION_ST_DONE:
+                status = APR_EOF;
+                goto out;
+                
+            default:
+                ap_log_cerror(APLOG_MARK, APLOG_ERR, APR_EGENERAL, c,
+                              "h2_session(%ld): unknown state %d", session->id, session->state);
+                dispatch_event(session, H2_SESSION_EV_PROTO_ERROR, 0, NULL);
+                break;
+        }
+
+        if (have_written) {
+            h2_conn_io_flush(&session->io);
+        }
+        else if (!nghttp2_session_want_read(session->ngh2) 
+                 && !nghttp2_session_want_write(session->ngh2)) {
+            dispatch_event(session, H2_SESSION_EV_NGH2_DONE, 0, NULL); 
+        }
+    }
+    
+out:
+    if (have_written) {
+        h2_conn_io_flush(&session->io);
+    }
+    
+    ap_log_cerror( APLOG_MARK, APLOG_TRACE1, status, c,
+                  "h2_session(%ld): [%s] process returns", 
+                  session->id, state_name(session->state));
+
+    if ((session->state != H2_SESSION_ST_DONE)
+        && (APR_STATUS_IS_EOF(status)
+            || APR_STATUS_IS_ECONNRESET(status) 
+            || APR_STATUS_IS_ECONNABORTED(status))) {
+            dispatch_event(session, H2_SESSION_EV_CONN_ERROR, 0, NULL);
+        }
+
+    status = (session->state == H2_SESSION_ST_DONE)? APR_EOF : APR_SUCCESS;
+    if (session->state == H2_SESSION_ST_DONE) {
+        if (!session->eoc_written) {
+            session->eoc_written = 1;
+            h2_conn_io_write_eoc(&session->io, 
+                                 h2_bucket_eoc_create(session->c->bucket_alloc, session));
+        }
+    }
+    
+    return status;
+}