[CRIU] [PATCH] tcp: refresh a data about tcp connection after blocking it

[Andrey Vagin]

We have a window between getting info about tcp connections
and blocking them. States of tcp connections can be changes,
so they should be refreshed after blocking.

https://bugzilla.openvz.org/show_bug.cgi?id=2419

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 sk-inet.c |  2 ++
 sk-tcp.c  | 42 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/sk-inet.c b/sk-inet.c
index f425704..2b9abc8 100644
--- a/sk-inet.c
+++ b/sk-inet.c
@@ -8,6 +8,8 @@
 #include <arpa/inet.h>
 #include <string.h>
 #include <stdlib.h>
+#include <sys/ioctl.h>
+#include <linux/sockios.h>
 
 #include "types.h"
 #include "libnetlink.h"
diff --git a/sk-tcp.c b/sk-tcp.c
index 9e01a08..99c8de2 100644
--- a/sk-tcp.c
+++ b/sk-tcp.c
@@ -51,6 +51,43 @@ static int tcp_repair_on(int fd)
 	return ret;
 }
 
+static int refresh_inet_sk(int fd, struct inet_sk_desc *sk)
+{
+	int size;
+	struct tcp_info info;
+
+	if (sk->state == TCP_CLOSE)
+		return 0;
+
+	if (dump_opt(fd, SOL_TCP, TCP_INFO, &info)) {
+		pr_perror("Failt to obtain TCP_INFO");
+		return -1;
+	}
+
+	sk->state = info.tcpi_state;
+
+	if (sk->state == TCP_LISTEN) {
+		sk->rqlen = info.tcpi_unacked;
+		sk->wqlen = info.tcpi_sacked;
+	} else {
+		if (ioctl(fd, SIOCOUTQ, &size) == -1) {
+			pr_perror("Unable to get size of snd queue");
+			return -1;
+		}
+
+		sk->wqlen = size;
+
+		if (ioctl(fd, SIOCINQ, &size) == -1) {
+			pr_perror("Unable to get size of recv queue");
+			return -1;
+		}
+
+		sk->rqlen = size;
+	}
+
+	return 0;
+}
+
 static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
 {
 	int ret;
@@ -71,6 +108,11 @@ static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
 		ret = nf_lock_connection(sk);
 		if (ret < 0)
 			goto err2;
+
+		/* A state of a tcp connection could be changed */
+		ret = refresh_inet_sk(sk->rfd, sk);
+		if (ret < 0)
+			goto err2;
 	}
 
 	ret = tcp_repair_on(sk->rfd);
-- 
1.7.11.7