tcp: Add code for "check"-ing TCP repair support

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-check.c

@@ -8,6 +8,8 @@
 #include "log.h"
 #include "util-net.h"
 #include "syscall.h"
+#include "files.h"
+#include "sk-inet.h"
 
 static int check_map_files(void)
 {
@@ -150,6 +152,7 @@ int cr_check(void)
 	ret |= check_prctl();
 	ret |= check_fcntl();
 	ret |= check_proc_stat();
+	ret |= check_tcp_repair();
 
 	if (!ret)
 		pr_msg("Looks good.\n");

include/sk-inet.h

@@ -39,4 +39,6 @@ int restore_one_tcp(int sk, struct inet_sk_info *si);
 
 struct cr_options;
 void show_tcp_stream(int fd, struct cr_options *);
+
+int check_tcp_repair(void);
 #endif

sk-tcp.c

@@ -46,7 +46,7 @@ static int tcp_repair_on(int fd)
 
 	ret = setsockopt(fd, SOL_TCP, TCP_REPAIR, &aux, sizeof(aux));
 	if (ret < 0)
-		pr_perror("Can't turn repair ON");
+		pr_perror("Can't turn TCP repair mode ON");
 
 	return ret;
 }
@@ -537,3 +537,19 @@ void show_tcp_stream(int fd, struct cr_options *opt)
 
 	pr_img_tail(CR_FD_TCP_STREAM);
 }
+
+int check_tcp_repair(void)
+{
+	int sk, ret;
+
+	sk = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (sk < 0) {
+		pr_perror("Can't create TCP socket :(\n");
+		return -1;
+	}
+
+	ret = tcp_repair_on(sk);
+	close(sk);
+
+	return ret;
+}