Simple test program to check the behaviour we need for bind() address
conflicts between listening sockets and repair mode sockets.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
doc/platform-requirements/.gitignore | 1 +
doc/platform-requirements/Makefile | 4 +-
doc/platform-requirements/listen-vs-repair.c | 128 +++++++++++++++++++
3 files changed, 131 insertions(+), 2 deletions(-)
create mode 100644 doc/platform-requirements/listen-vs-repair.c
diff --git a/doc/platform-requirements/.gitignore b/doc/platform-requirements/.gitignore
index 3b5a10ac..f6272cf0 100644
--- a/doc/platform-requirements/.gitignore
+++ b/doc/platform-requirements/.gitignore
@@ -1,3 +1,4 @@
+/listen-vs-repair
/reuseaddr-priority
/recv-zero
/udp-close-dup
diff --git a/doc/platform-requirements/Makefile b/doc/platform-requirements/Makefile
index 6a7d3748..83930ef8 100644
--- a/doc/platform-requirements/Makefile
+++ b/doc/platform-requirements/Makefile
@@ -3,8 +3,8 @@
# Copyright Red Hat
# Author: David Gibson <david(a)gibson.dropbear.id.au>
-TARGETS = reuseaddr-priority recv-zero udp-close-dup
-SRCS = reuseaddr-priority.c recv-zero.c udp-close-dup.c
+TARGETS = reuseaddr-priority recv-zero udp-close-dup listen-vs-repair
+SRCS = reuseaddr-priority.c recv-zero.c udp-close-dup.c listen-vs-repair.c
CFLAGS = -Wall
all: cppcheck clang-tidy $(TARGETS:%=check-%)
diff --git a/doc/platform-requirements/listen-vs-repair.c
b/doc/platform-requirements/listen-vs-repair.c
new file mode 100644
index 00000000..d31fe3f7
--- /dev/null
+++ b/doc/platform-requirements/listen-vs-repair.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* liste-vs-repair.c
+ *
+ * Do listening sockets have address conflicts with sockets under repair
+ * ====================================================================
+ *
+ * When we accept() an incoming connection the accept()ed socket will have the
+ * same local address as the listening socket. This can be a complication on
+ * migration. On the migration target we've already set up listening sockets
+ * according to the command line. However to restore connections that we're
+ * migrating in we need to bind the new sockets to the same address, which would
+ * be an address conflict on the face of it. This test program verifies that
+ * enabling repair mode before bind() correctly suppresses that conflict.
+ *
+ * Copyright Red Hat
+ * Author: David Gibson <david(a)gibson.dropbear.id.au>
+ */
+
+/* NOLINTNEXTLINE(bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp) */
+#define _GNU_SOURCE
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "common.h"
+
+#define PORT 13256U
+#define CPORT 13257U
+
+/* 127.0.0.1:PORT */
+static const struct sockaddr_in addr = SOCKADDR_INIT(INADDR_LOOPBACK, PORT);
+
+/* 127.0.0.1:CPORT */
+static const struct sockaddr_in caddr = SOCKADDR_INIT(INADDR_LOOPBACK, CPORT);
+
+/* Put ourselves into a network sandbox */
+static void net_sandbox(void)
+{
+ /* NOLINTNEXTLINE(altera-struct-pack-align) */
+ const struct req_t {
+ struct nlmsghdr nlh;
+ struct ifinfomsg ifm;
+ } __attribute__((packed)) req = {
+ .nlh.nlmsg_type = RTM_NEWLINK,
+ .nlh.nlmsg_flags = NLM_F_REQUEST,
+ .nlh.nlmsg_len = sizeof(req),
+ .nlh.nlmsg_seq = 1,
+ .ifm.ifi_family = AF_UNSPEC,
+ .ifm.ifi_index = 1,
+ .ifm.ifi_flags = IFF_UP,
+ .ifm.ifi_change = IFF_UP,
+ };
+ int nl;
+
+ if (unshare(CLONE_NEWUSER | CLONE_NEWNET))
+ die("unshare(): %s\n", strerror(errno));
+
+ /* Bring up lo in the new netns */
+ nl = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
+ if (nl < 0)
+ die("Can't create netlink socket: %s\n", strerror(errno));
+
+ if (send(nl, &req, sizeof(req), 0) < 0)
+ die("Netlink send(): %s\n", strerror(errno));
+ close(nl);
+}
+
+static void check(void)
+{
+ int s1, s2, op;
+
+ s1 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+ if (s1 < 0)
+ die("socket() 1: %s\n", strerror(errno));
+
+ if (bind(s1, (struct sockaddr *)&addr, sizeof(addr)))
+ die("bind() 1: %s\n", strerror(errno));
+
+ if (listen(s1, 0))
+ die("listen(): %s\n", strerror(errno));
+
+ s2 = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+ if (s2 < 0)
+ die("socket() 2: %s\n", strerror(errno));
+
+ op = TCP_REPAIR_ON;
+ if (setsockopt(s2, SOL_TCP, TCP_REPAIR, &op, sizeof(op)))
+ die("TCP_REPAIR: %s\n", strerror(errno));
+
+ if (bind(s2, (struct sockaddr *)&addr, sizeof(addr)))
+ die("bind() 2: %s\n", strerror(errno));
+
+ if (connect(s2, (struct sockaddr *)&caddr, sizeof(caddr)))
+ die("connect(): %s\n", strerror(errno));
+
+ op = TCP_REPAIR_OFF_NO_WP;
+ if (setsockopt(s2, SOL_TCP, TCP_REPAIR, &op, sizeof(op)))
+ die("TCP_REPAIR: %s\n", strerror(errno));
+
+ close(s1);
+ close(s2);
+}
+
+int main(int argc, char *argv[])
+{
+ (void)argc;
+ (void)argv;
+
+ net_sandbox();
+
+ check();
+
+ printf("Repair mode appears to properly suppress conflicts with listening
sockets\n");
+
+ exit(0);
+}
--
2.49.0