From: Volker Lendecke <vl@samba.org>
Date: Sat, 12 Jun 2021 10:45:30 +0000 (+0200)
Subject: rpc_server: Don't rely on TCP-bind() to return EADDRINUSE
X-Git-Tag: tevent-0.11.0~381
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa147153c10b94e2db40d772677efacd5d0b31ee;p=thirdparty%2Fsamba.git

rpc_server: Don't rely on TCP-bind() to return EADDRINUSE

socket_wrapper can't do EADDRINUSE because unix domain sockets don't
do it.

This currently works correctly because right now all RPC servers
either use explicit ports or all listen on the same socket.

The new code uses a static variable, so it only helps if a single
process listens for multiple RPC sockets. It won't work if multiple
processes start listening. But in case samba-dcerpcd goes in this will
be exactly the right thing to do.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
---

diff --git a/source3/rpc_server/rpc_sock_helper.c b/source3/rpc_server/rpc_sock_helper.c
index 22a0cd17aeb..8ae637a71b4 100644
--- a/source3/rpc_server/rpc_sock_helper.c
+++ b/source3/rpc_server/rpc_sock_helper.c
@@ -117,12 +117,18 @@ static NTSTATUS dcesrv_create_ncacn_ip_tcp_socket(
 	int fd = -1;
 
 	if (*port == 0) {
+		static uint16_t low = 0;
 		uint16_t i;
 
-		for (i = lp_rpc_low_port(); i <= lp_rpc_high_port(); i++) {
+		if (low == 0) {
+			low = lp_rpc_low_port();
+		}
+
+		for (i = low; i <= lp_rpc_high_port(); i++) {
 			fd = open_socket_in(SOCK_STREAM, ifss, i, false);
 			if (fd >= 0) {
 				*port = i;
+				low = i+1;
 				break;
 			}
 		}