From: Willy Tarreau <w@1wt.eu>
Date: Thu, 31 Jan 2019 09:34:07 +0000 (+0100)
Subject: MINOR: mux-h2: learn and store the peer's advertised MAX_CONCURRENT_STREAMS setting
X-Git-Tag: v2.0-dev1~87
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2e2083ae5b2aafcb05eac79aba92d74803b56a52;p=thirdparty%2Fhaproxy.git

MINOR: mux-h2: learn and store the peer's advertised MAX_CONCURRENT_STREAMS setting

We used not to take it into account because we only used the configured
parameter everywhere. This patch makes sure we can actually learn the
value advertised by the peer. We still enforce our own limit on top of
it however, to make sure we can actually limit resources or stream
concurrency in case of suboptimal server settings.
---

diff --git a/src/mux_h2.c b/src/mux_h2.c
index 648f0d2a3a..4c87d7226e 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -87,6 +87,7 @@ struct h2c {
 
 	/* 16 bit hole here */
 	uint32_t flags; /* connection flags: H2_CF_* */
+	uint32_t streams_limit; /* maximum number of concurrent streams the peer supports */
 	int32_t max_id; /* highest ID known on this connection, <0 before preface */
 	uint32_t rcvd_c; /* newly received data to ACK for the connection */
 	uint32_t rcvd_s; /* newly received data to ACK for the current stream (dsi) */
@@ -503,6 +504,7 @@ static int h2_init(struct connection *conn, struct proxy *prx, struct session *s
 	/* Initialise the context. */
 	h2c->st0 = H2_CS_PREFACE;
 	h2c->conn = conn;
+	h2c->streams_limit = h2_settings_max_concurrent_streams;
 	h2c->max_id = -1;
 	h2c->errcode = H2_ERR_NO_ERROR;
 	h2c->rcvd_c = 0;
@@ -1495,6 +1497,14 @@ static int h2c_handle_settings(struct h2c *h2c)
 				goto fail;
 			}
 			break;
+		case H2_SETTINGS_MAX_CONCURRENT_STREAMS:
+			if (h2c->flags & H2_CF_IS_BACK) {
+				/* the limit is only for the backend; for the frontend it is our limit */
+				if ((unsigned int)arg > h2_settings_max_concurrent_streams)
+					arg = h2_settings_max_concurrent_streams;
+				h2c->streams_limit = arg;
+			}
+			break;
 		}
 	}