MEDIUM: h2: send WINDOW_UPDATE frames for connection
When it is detected that the number of received bytes is > 0 on the
connection at the end of the demux call or before starting to process
pending output data, an attempt is made at sending a WINDOW UPDATE on
the connection. In case of failure, it's attempted later.
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 0b4165e..b2584f5 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -966,6 +966,87 @@
return 1;
}
+/* Try to send a window update for stream id <sid> and value <increment>.
+ * Returns > 0 on success or zero on missing room or failure. It may return an
+ * error in h2c.
+ */
+static int h2c_send_window_update(struct h2c *h2c, int sid, uint32_t increment)
+{
+ struct buffer *res;
+ char str[13];
+ int ret = -1;
+
+ if (h2c_mux_busy(h2c, NULL)) {
+ h2c->flags |= H2_CF_DEM_MBUSY;
+ return 0;
+ }
+
+ res = h2_get_mbuf(h2c);
+ if (!res) {
+ h2c->flags |= H2_CF_MUX_MALLOC;
+ h2c->flags |= H2_CF_DEM_MROOM;
+ return 0;
+ }
+
+ /* length: 4, type: 8, flags: none */
+ memcpy(str, "\x00\x00\x04\x08\x00", 5);
+ write_n32(str + 5, sid);
+ write_n32(str + 9, increment);
+
+ ret = bo_istput(res, ist2(str, 13));
+
+ if (unlikely(ret <= 0)) {
+ if (!ret) {
+ h2c->flags |= H2_CF_MUX_MFULL;
+ h2c->flags |= H2_CF_DEM_MROOM;
+ return 0;
+ }
+ else {
+ h2c_error(h2c, H2_ERR_INTERNAL_ERROR);
+ return 0;
+ }
+ }
+ return ret;
+}
+
+/* try to send pending window update for the connection. It's safe to call it
+ * with no pending updates. Returns > 0 on success or zero on missing room or
+ * failure. It may return an error in h2c.
+ */
+static int h2c_send_conn_wu(struct h2c *h2c)
+{
+ int ret = 1;
+
+ if (h2c->rcvd_c <= 0)
+ return 1;
+
+ /* send WU for the connection */
+ ret = h2c_send_window_update(h2c, 0, h2c->rcvd_c);
+ if (ret > 0)
+ h2c->rcvd_c = 0;
+
+ return ret;
+}
+
+/* try to send pending window update for the current dmux stream. It's safe to
+ * call it with no pending updates. Returns > 0 on success or zero on missing
+ * room or failure. It may return an error in h2c.
+ */
+static int h2c_send_strm_wu(struct h2c *h2c)
+{
+ int ret = 1;
+
+ if (h2c->rcvd_s <= 0)
+ return 1;
+
+ /* send WU for the stream */
+ ret = h2c_send_window_update(h2c, h2c->dsi, h2c->rcvd_s);
+ if (ret > 0)
+ h2c->rcvd_s = 0;
+
+ return ret;
+}
+
/* try to send an ACK for a ping frame on the connection. Returns > 0 on
* success, 0 on missing data or one of the h2_status values.
*/
@@ -1335,6 +1416,10 @@
}
}
+ if (h2c->rcvd_c > 0 &&
+ !(h2c->flags & (H2_CF_MUX_MFULL | H2_CF_DEM_MBUSY | H2_CF_DEM_MROOM)))
+ h2c_send_conn_wu(h2c);
+
fail:
/* we can go here on missing data, blocked response or error */
return;
@@ -1347,6 +1432,12 @@
{
struct h2s *h2s, *h2s_back;
+ /* start by sending possibly pending window updates */
+ if (h2c->rcvd_c > 0 &&
+ !(h2c->flags & (H2_CF_MUX_MFULL | H2_CF_MUX_MALLOC)) &&
+ h2c_send_conn_wu(h2c) < 0)
+ goto fail;
+
/* First we always process the flow control list because the streams
* waiting there were already elected for immediate emission but were
* blocked just on this.
@@ -1427,6 +1518,7 @@
}
}
+ fail:
if (unlikely(h2c->st0 > H2_CS_ERROR)) {
if (h2c->st0 == H2_CS_ERROR) {
if (h2c->max_id >= 0) {