From 52eed75ced5d9a89807ca272ddbc618c74e62edd Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Fri, 22 Sep 2017 15:05:09 +0200
Subject: [PATCH] MINOR: h2: match the H2 connection preface on init

The H2 preface is properly detected to switch to the settings state.
It's important to note that for now we don't send out settings frame
so the operation is not complete yet.
---
 src/mux_h2.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/src/mux_h2.c b/src/mux_h2.c
index 57070bf70..08cc574ef 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -581,6 +581,27 @@ static struct h2s *h2c_stream_new(struct h2c *h2c, int id)
 	return h2s;
 }
 
+/* Try to receive a connection preface, then upon success try to send our
+ * preface which is a SETTINGS frame. Returns > 0 on success or zero on
+ * missing data. It may return an error in h2c.
+ */
+static int h2c_frt_recv_preface(struct h2c *h2c)
+{
+	int ret1;
+
+	ret1 = b_isteq(h2c->dbuf, 0, h2c->dbuf->i, ist(H2_CONN_PREFACE));
+
+	if (unlikely(ret1 <= 0)) {
+		if (ret1 < 0 || conn_xprt_read0_pending(h2c->conn))
+			h2c_error(h2c, H2_ERR_PROTOCOL_ERROR);
+		return 0;
+	}
+
+	bi_del(h2c->dbuf, ret1);
+
+	return ret1;
+}
+
 /* try to send a GOAWAY frame on the connection to report an error or a graceful
  * shutdown, with h2c->errcode as the error code. Returns > 0 on success or zero
  * if nothing was done. It uses h2c->last_sid as the advertised ID, or copies it
@@ -653,6 +674,26 @@ static void h2_process_demux(struct h2c *h2c)
 {
 	if (h2c->st0 >= H2_CS_ERROR)
 		return;
+
+	if (unlikely(h2c->st0 < H2_CS_FRAME_H)) {
+		if (h2c->st0 == H2_CS_PREFACE) {
+			if (unlikely(h2c_frt_recv_preface(h2c) <= 0)) {
+				/* RFC7540#3.5: a GOAWAY frame MAY be omitted */
+				if (h2c->st0 == H2_CS_ERROR)
+					h2c->st0 = H2_CS_ERROR2;
+				goto fail;
+			}
+
+			h2c->max_id = 0;
+			h2c->st0 = H2_CS_SETTINGS1;
+		}
+		/* deal with SETTINGS here */
+	}
+	return;
+
+ fail:
+	/* we can go here on missing data, blocked response or error */
+	return;
 }
 
 /* process Tx frames from streams to be multiplexed. Returns > 0 if it reached