MINOR: server: convert @reverse to rev@ standard format

Remove the recently introduced '@reverse' notation for HTTP reverse
servers. Instead, reuse the 'rev@' prefix already defined for bind
lines.

doc/configuration.txt

@@ -11534,18 +11534,13 @@ server <name> <address>[:[port]] [param*]
                       one of them over the FD. The bind part will use the
                       received socket as the client FD. Should be used
                       carefully.
+                    - 'rev@'   -> custom address family for a passive server in
+                      HTTP reverse context.
               You may want to reference some environment variables in the
               address parameter, see section 2.3 about environment
               variables. The "init-addr" setting can be used to modify the way
               IP addresses should be resolved upon startup.
 
-              Additionally, there is a special address notation defined for
-              servers which does not have any address assigned. Currently, only
-              '@reverse' is valid. This instantiates a server which can only be
-              used with reverse connect. This mode requires the proxy to be in
-              HTTP mode and the server to explicitly use HTTP/2, either through
-              'proto' or 'alpn' keywords.
-
     <port>    is an optional port specification. If set, all connections will
               be sent to this port. If unset, the same port the client
               connected to will be used. The port may also be prefixed by a "+"

include/haproxy/proto_reverse_connect.h

@@ -14,6 +14,8 @@ struct connection *rev_accept_conn(struct listener *l, int *status);
 void rev_unbind_receiver(struct listener *l);
 int rev_set_affinity(struct connection *conn, int new_tid);
 
+int rev_connect(struct connection *conn, int flags);
+
 int rev_accepting_conn(const struct receiver *rx);
 
 void rev_notify_preconn_err(struct listener *l);

reg-tests/connection/reverse_connect_full.vtc

@@ -21,7 +21,7 @@ frontend pub
 	use_backend be-reverse
 
 backend be-reverse
-	server dev @reverse
+	server dev rev@
 
 frontend priv
 	bind "fd@${priv}" proto h2

reg-tests/connection/reverse_server.vtc

@@ -18,7 +18,7 @@ frontend pub
 	use_backend be-reverse
 
 backend be-reverse
-	server dev @reverse
+	server dev rev@
 
 frontend priv
 	bind "fd@${priv}" proto h2

reg-tests/connection/reverse_server_name.vtc

@@ -19,7 +19,7 @@ frontend pub
 	use_backend be-reverse
 
 backend be-reverse
-	server dev @reverse ssl sni hdr(x-name) verify none
+	server dev rev@ ssl sni hdr(x-name) verify none
 
 frontend priv
 	bind "fd@${priv}" ssl crt ${testdir}/common.pem verify required ca-verify-file ${testdir}/ca-auth.crt alpn h2

src/proto_reverse_connect.c

@@ -36,6 +36,8 @@ struct protocol proto_reverse_connect = {
 	.accept_conn = rev_accept_conn,
 	.set_affinity = rev_set_affinity,
 
+	.connect     = rev_connect,
+
 	/* address family */
 	.fam  = &proto_fam_reverse_connect,
 
@@ -343,6 +345,12 @@ int rev_set_affinity(struct connection *conn, int new_tid)
 	return -1;
 }
 
+/* Simple callback to enable definition of passive HTTP reverse servers. */
+int rev_connect(struct connection *conn, int flags)
+{
+	return SF_ERR_NONE;
+}
+
 int rev_accepting_conn(const struct receiver *rx)
 {
 	return 1;

src/server.c

@@ -2805,22 +2805,6 @@ static int _srv_parse_init(struct server **srv, char **args, int *cur_arg,
 		else
 			newsrv->tmpl_info.prefix = strdup(args[1]);
 
-		/* special address specifier */
-		if (args[*cur_arg][0] == '@') {
-			if (strcmp(args[*cur_arg], "@reverse") == 0) {
-				newsrv->flags |= SRV_F_REVERSE;
-			}
-			else {
-				ha_alert("unknown server address specifier '%s'\n",
-				         args[*cur_arg]);
-				err_code |= ERR_ALERT | ERR_FATAL;
-				goto out;
-			}
-
-			(*cur_arg)++;
-			parse_flags &= ~SRV_PARSE_PARSE_ADDR;
-		}
-
 		/* several ways to check the port component :
 		 *  - IP    => port=+0, relative (IPv4 only)
 		 *  - IP:   => port=+0, relative
@@ -2845,8 +2829,13 @@ static int _srv_parse_init(struct server **srv, char **args, int *cur_arg,
 		}
 
 		if (!port1 || !port2) {
-			/* no port specified, +offset, -offset */
-			newsrv->flags |= SRV_F_MAPPORTS;
+			if (sk->ss_family != AF_CUST_REV_SRV) {
+				/* no port specified, +offset, -offset */
+				newsrv->flags |= SRV_F_MAPPORTS;
+			}
+			else {
+				newsrv->flags |= SRV_F_REVERSE;
+			}
 		}
 
 		/* save hostname and create associated name resolution */