MEDIUM: server/backend: implement websocket protocol selection
Handle properly websocket streams if the server uses an ALPN with both
h1 and h2. Add a new field h2_ws in the server structure. If set to off,
reuse is automatically disable on backend and ALPN is forced to http1.x
if possible. Nothing is done if on.
Implement a mechanism to be able to use a different http version for
websocket streams. A new server member <ws> represents the algorithm to
select the protocol. This can overrides the server <proto>
configuration. If the connection uses ALPN for proto selection, it is
updated for websocket streams to select the right protocol.
Three mode of selection are implemented :
- auto : use the same protocol between non-ws and ws streams. If ALPN is
use, try to update it to "http/1.1"; this is only done if the server
ALPN contains "http/1.1".
- h1 : use http/1.1
- h2 : use http/2.0; this requires the server to support RFC8441 or an
error will be returned by haproxy.
(cherry picked from commit 9c3251d1087061f3a0c88f69b8f62ec1f9324bd7)
[ad: adjusted context: skip reuse move in connect_server; refcount field
in server structure renamed]
Signed-off-by: Amaury Denoyelle <adenoyelle@haproxy.com>
diff --git a/src/server.c b/src/server.c
index 69aa514..6989f85 100644
--- a/src/server.c
+++ b/src/server.c
@@ -197,6 +197,94 @@
HA_RWLOCK_RDUNLOCK(PROXY_LOCK, &p->lock);
}
+/* Returns true if it's possible to reuse an idle connection from server <srv>
+ * for a websocket stream. This is the case if server is configured to use the
+ * same protocol for both HTTP and websocket streams. This depends on the value
+ * of "proto", "alpn" and "ws" keywords.
+ */
+int srv_check_reuse_ws(struct server *srv)
+{
+ if (srv->mux_proto || srv->use_ssl != 1 || !srv->ssl_ctx.alpn_str) {
+ /* explicit srv.mux_proto or no ALPN : srv.mux_proto is used
+ * for mux selection.
+ */
+ const struct ist srv_mux = srv->mux_proto ?
+ srv->mux_proto->token : IST_NULL;
+
+ switch (srv->ws) {
+ /* "auto" means use the same protocol : reuse is possible. */
+ case SRV_WS_AUTO:
+ return 1;
+
+ /* "h2" means use h2 for websocket : reuse is possible if
+ * server mux is h2.
+ */
+ case SRV_WS_H2:
+ if (srv->mux_proto && isteq(srv_mux, ist("h2")))
+ return 1;
+ break;
+
+ /* "h1" means use h1 for websocket : reuse is possible if
+ * server mux is h1.
+ */
+ case SRV_WS_H1:
+ if (!srv->mux_proto || isteq(srv_mux, ist("h1")))
+ return 1;
+ break;
+ }
+ }
+ else {
+ /* ALPN selection.
+ * Based on the assumption that only "h2" and "http/1.1" token
+ * are used on server ALPN.
+ */
+ const struct ist alpn = ist2(srv->ssl_ctx.alpn_str,
+ srv->ssl_ctx.alpn_len);
+
+ switch (srv->ws) {
+ case SRV_WS_AUTO:
+ /* for auto mode, consider reuse as possible if the
+ * server uses a single protocol ALPN
+ */
+ if (!istchr(alpn, ','))
+ return 1;
+ break;
+
+ case SRV_WS_H2:
+ return isteq(alpn, ist("\x02h2"));
+
+ case SRV_WS_H1:
+ return isteq(alpn, ist("\x08http/1.1"));
+ }
+ }
+
+ return 0;
+}
+
+/* Return the proto to used for a websocket stream on <srv> without ALPN. NULL
+ * is a valid value indicating to use the fallback mux.
+ */
+const struct mux_ops *srv_get_ws_proto(struct server *srv)
+{
+ const struct mux_proto_list *mux = NULL;
+
+ switch (srv->ws) {
+ case SRV_WS_AUTO:
+ mux = srv->mux_proto;
+ break;
+
+ case SRV_WS_H1:
+ mux = get_mux_proto(ist("h1"));
+ break;
+
+ case SRV_WS_H2:
+ mux = get_mux_proto(ist("h2"));
+ break;
+ }
+
+ return mux ? mux->mux : NULL;
+}
+
/*
* Must be called with the server lock held. The server is first removed from
* the proxy tree if it was already attached. If <reattach> is true, the server
@@ -2094,6 +2182,7 @@
srv->agent.fastinter = src->agent.fastinter;
srv->agent.downinter = src->agent.downinter;
srv->maxqueue = src->maxqueue;
+ srv->ws = src->ws;
srv->minconn = src->minconn;
srv->maxconn = src->maxconn;
srv->slowstart = src->slowstart;