soccr/tcp: Add _pause and _resume to library and use it

The calls put socket into a mode where it can be saved or
restored. Add take one out of this mode.

TODO: In criu we turn repair off (resume the socket) from
restorer blob that cannot use the library. Need to somehow
fix it.
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/include/sk-inet.h

@@ -32,6 +32,8 @@ struct inet_sk_desc {
 	int rfd;
 	int cpt_reuseaddr;
 	struct list_head rlist;
+
+	void *priv;
 };
 
 struct inet_port;

criu/sk-tcp.c

@@ -137,6 +137,7 @@ static int refresh_inet_sk(struct inet_sk_desc *sk, struct tcp_info *ti)
 static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
 {
 	int ret;
+	struct libsoccr_sk *socr;
 
 	pr_info("\tTurning repair on for socket %x\n", sk->sd.ino);
 	/*
@@ -156,10 +157,11 @@ static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
 			goto err2;
 	}
 
-	ret = tcp_repair_on(sk->rfd);
-	if (ret < 0)
+	socr = libsoccr_pause(sk->rfd);
+	if (!socr)
 		goto err3;
 
+	sk->priv = socr;
 	list_add_tail(&sk->rlist, &cpt_tcp_repair_sockets);
 	return 0;
 
@@ -184,7 +186,8 @@ static void tcp_unlock_one(struct inet_sk_desc *sk)
 			pr_perror("Failed to unlock TCP connection");
 	}
 
-	tcp_repair_off(sk->rfd);
+	libsoccr_resume(sk->priv);
+	sk->priv = NULL;
 
 	/*
 	 * tcp_repair_off modifies SO_REUSEADDR so
@@ -679,7 +682,7 @@ static int restore_tcp_window(int sk, TcpStreamEntry *tse)
 	return 0;
 }
 
-static int restore_tcp_conn_state(int sk, struct inet_sk_info *ii)
+static int restore_tcp_conn_state(int sk, struct libsoccr_sk *socr, struct inet_sk_info *ii)
 {
 	int aux;
 	struct cr_img *img;
@@ -769,12 +772,15 @@ int prepare_tcp_socks(struct task_restore_args *ta)
 
 int restore_one_tcp(int fd, struct inet_sk_info *ii)
 {
+	struct libsoccr_sk *sk;
+
 	pr_info("Restoring TCP connection\n");
 
-	if (tcp_repair_on(fd))
+	sk = libsoccr_pause(fd);
+	if (!sk)
 		return -1;
 
-	if (restore_tcp_conn_state(fd, ii))
+	if (restore_tcp_conn_state(fd, sk, ii))
 		return -1;
 
 	return 0;

soccr/soccr.c

+#include <netinet/tcp.h>
+#include <stdlib.h>
 #include "soccr.h"
 
 static void (*log)(unsigned int loglevel, const char *format, ...)
@@ -12,3 +14,50 @@ void libsoccr_set_log(unsigned int level, void (*fn)(unsigned int level, const c
 
 #define loge(msg, ...) do { if (log && (log_level >= SOCCR_LOG_ERR)) log(SOCCR_LOG_ERR, msg, ##__VA_ARGS__); } while (0)
 #define logd(msg, ...) do { if (log && (log_level >= SOCCR_LOG_DBG)) log(SOCCR_LOG_DBG, msg, ##__VA_ARGS__); } while (0)
+
+static int tcp_repair_on(int fd)
+{
+	int ret, aux = 1;
+
+	ret = setsockopt(fd, SOL_TCP, TCP_REPAIR, &aux, sizeof(aux));
+	if (ret < 0)
+		loge("Can't turn TCP repair mode ON");
+
+	return ret;
+}
+
+static void tcp_repair_off(int fd)
+{
+	int aux = 0, ret;
+
+	ret = setsockopt(fd, SOL_TCP, TCP_REPAIR, &aux, sizeof(aux));
+	if (ret < 0)
+		loge("Failed to turn off repair mode on socket: %m\n");
+}
+
+struct libsoccr_sk {
+	int fd;
+};
+
+struct libsoccr_sk *libsoccr_pause(int fd)
+{
+	struct libsoccr_sk *ret;
+
+	ret = malloc(sizeof(*ret));
+	if (!ret)
+		return NULL;
+
+	if (tcp_repair_on(fd) < 0) {
+		free(ret);
+		return NULL;
+	}
+
+	ret->fd = fd;
+	return ret;
+}
+
+void libsoccr_resume(struct libsoccr_sk *sk)
+{
+	tcp_repair_off(sk->fd);
+	free(sk);
+}

soccr/soccr.h

@@ -9,4 +9,9 @@ void libsoccr_set_log(unsigned int level, void (*fn)(unsigned int level, const c
 #define SOCCR_LOG_ERR	1
 #define SOCCR_LOG_DBG	2
 
+struct libsoccr_sk;
+
+struct libsoccr_sk *libsoccr_pause(int fd);
+void libsoccr_resume(struct libsoccr_sk *sk);
+
 #endif