From: Willy Tarreau <w@1wt.eu>
Date: Tue, 17 Oct 2017 06:10:17 +0000 (+0200)
Subject: MINOR: h2: implement h2_send_rst_stream() to send RST_STREAM frames
X-Git-Tag: v1.8-rc1~28
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27a84c90ce57da78dff382d99d7829e90aee524a;p=thirdparty%2Fhaproxy.git

MINOR: h2: implement h2_send_rst_stream() to send RST_STREAM frames

This one sends an RST_STREAM for a given stream, using the current
demux stream ID. It's also used to send RST_STREAM for streams which
have lost their CS part (ie were aborted).
---

diff --git a/src/mux_h2.c b/src/mux_h2.c
index 855bd50b9e..72a4b507e8 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -753,6 +753,64 @@ static int h2c_send_goaway_error(struct h2c *h2c, struct h2s *h2s)
 	return ret;
 }
 
+/* try to send an RST_STREAM frame on the connection for the current demuxed
+ * stream to report an error, with h2s->errcode as the error code. Returns > 0
+ * on success or zero if nothing was done. It uses h2c->dsi as the stream ID
+ * and h2s->errcode for the error code. In case of lack of room to write the
+ * message, it subscribes the requester (either <h2s> or <h2c>) to future
+ * notifications. It's worth mentionning that an RST may even be sent for a
+ * closed stream with error 0 in this case.
+ */
+static int h2c_send_rst_stream(struct h2c *h2c, struct h2s *h2s)
+{
+	struct buffer *res;
+	char str[13];
+	int ret;
+
+	if (h2c_mux_busy(h2c, h2s)) {
+		if (h2s)
+			h2s->flags |= H2_SF_BLK_MBUSY;
+		else
+			h2c->flags |= H2_CF_DEM_MBUSY;
+		return 0;
+	}
+
+	res = h2_get_mbuf(h2c);
+	if (!res) {
+		h2c->flags |= H2_CF_MUX_MALLOC;
+		if (h2s)
+			h2s->flags |= H2_SF_BLK_MROOM;
+		else
+			h2c->flags |= H2_CF_DEM_MROOM;
+		return 0;
+	}
+
+	/* len: 4, type: 3, flags: none */
+	memcpy(str, "\x00\x00\x04\x03\x00", 5);
+	write_n32(str + 5, h2c->dsi);
+	write_n32(str + 9, (h2s->st > H2_SS_IDLE && h2s->st < H2_SS_RESET) ?
+		  h2s->errcode : H2_ERR_STREAM_CLOSED);
+	ret = bo_istput(res, ist2(str, 13));
+	if (unlikely(ret <= 0)) {
+		if (!ret) {
+			h2c->flags |= H2_CF_MUX_MFULL;
+			if (h2s)
+				h2s->flags |= H2_SF_BLK_MROOM;
+			else
+				h2c->flags |= H2_CF_DEM_MROOM;
+			return 0;
+		}
+		else {
+			h2c_error(h2c, H2_ERR_INTERNAL_ERROR);
+			return 0;
+		}
+	}
+
+	if (h2s)
+		h2s->flags |= H2_SF_RST_SENT;
+	return ret;
+}
+
 /* Increase all streams' outgoing window size by the difference passed in
  * argument. This is needed upon receipt of the settings frame if the initial
  * window size is different. The difference may be negative and the resulting
@@ -1158,6 +1216,15 @@ static void h2_process_demux(struct h2c *h2c)
 			ret = h2c->dfl == 0;
 		}
 
+		/* RST are sent similarly to frame acks */
+		if (h2s->st == H2_SS_ERROR) {
+			if (h2c->st0 == H2_CS_FRAME_P)
+				h2c->st0 = H2_CS_FRAME_A;
+
+			if (h2c->st0 == H2_CS_FRAME_A)
+				ret = h2c_send_rst_stream(h2c, h2s);
+		}
+
 		/* error or missing data condition met above ? */
 		if (ret <= 0)
 			break;
@@ -1203,6 +1270,8 @@ static int h2_process_mux(struct h2c *h2c)
 		if (h2s->cs) {
 			h2s->cs->data_cb->send(h2s->cs);
 			h2s->cs->data_cb->wake(h2s->cs);
+		} else {
+			h2c_send_rst_stream(h2c, h2s);
 		}
 
 		/* depending on callee's blocking reasons, we may queue in send
@@ -1239,6 +1308,8 @@ static int h2_process_mux(struct h2c *h2c)
 		if (h2s->cs) {
 			h2s->cs->data_cb->send(h2s->cs);
 			h2s->cs->data_cb->wake(h2s->cs);
+		} else {
+			h2c_send_rst_stream(h2c, h2s);
 		}
 		/* depending on callee's blocking reasons, we may queue in fctl
 		 * list or completely dequeue.