/*

 * namespace.c

 *

 *		This program is free software; you can redistribute it and/or

 *		modify it under the terms of the GNU General Public License

 *		as published by the Free Software Foundation; either version

 *		2 of the License, or (at your option) any later version.

 */

#include <sys/statvfs.h>

#include <fcntl.h>

#include <dirent.h>

#include <limits.h>

#include "utils.h"

#include "namespace.h"

static void bind_etc(const char *name)

{

	char etc_netns_path[sizeof(NETNS_ETC_DIR) + NAME_MAX];

	char netns_name[PATH_MAX];

	char etc_name[PATH_MAX];

	struct dirent *entry;

	DIR *dir;

	if (strlen(name) >= NAME_MAX)

		return;

	snprintf(etc_netns_path, sizeof(etc_netns_path), "%s/%s", NETNS_ETC_DIR, name);

	dir = opendir(etc_netns_path);

	if (!dir)

		return;

	while ((entry = readdir(dir)) != NULL) {

		if (strcmp(entry->d_name, ".") == 0)

			continue;

		if (strcmp(entry->d_name, "..") == 0)

			continue;

		snprintf(netns_name, sizeof(netns_name), "%s/%s", etc_netns_path, entry->d_name);

		snprintf(etc_name, sizeof(etc_name), "/etc/%s", entry->d_name);

		if (mount(netns_name, etc_name, "none", MS_BIND, NULL) < 0) {

			fprintf(stderr, "Bind %s -> %s failed: %s\n",

				netns_name, etc_name, strerror(errno));

		}

	}

	closedir(dir);

}

int netns_switch(char *name)

{

	char net_path[PATH_MAX];

	int netns;

	unsigned long mountflags = 0;

	struct statvfs fsstat;

	snprintf(net_path, sizeof(net_path), "%s/%s", NETNS_RUN_DIR, name);

	netns = open(net_path, O_RDONLY | O_CLOEXEC);

	if (netns < 0) {

		fprintf(stderr, "Cannot open network namespace \"%s\": %s\n",

			name, strerror(errno));

		return -1;

	}

	if (setns(netns, CLONE_NEWNET) < 0) {

		fprintf(stderr, "setting the network namespace \"%s\" failed: %s\n",

			name, strerror(errno));

		close(netns);

		return -1;

	}

	close(netns);

	if (unshare(CLONE_NEWNS) < 0) {

		fprintf(stderr, "unshare failed: %s\n", strerror(errno));

		return -1;

	}

	/* Don't let any mounts propagate back to the parent */

	if (mount("", "/", "none", MS_SLAVE | MS_REC, NULL)) {

		fprintf(stderr, "\"mount --make-rslave /\" failed: %s\n",

			strerror(errno));

		return -1;

	}

	/* Mount a version of /sys that describes the network namespace */

	if (umount2("/sys", MNT_DETACH) < 0) {

		/* If this fails, perhaps there wasn't a sysfs instance mounted. Good. */

		if (statvfs("/sys", &fsstat) == 0) {

			/* We couldn't umount the sysfs, we'll attempt to overlay it.

			 * A read-only instance can't be shadowed with a read-write one. */

			if (fsstat.f_flag & ST_RDONLY)

				mountflags = MS_RDONLY;

		}

	}

	if (mount(name, "/sys", "sysfs", mountflags, NULL) < 0) {

		fprintf(stderr, "mount of /sys failed: %s\n",strerror(errno));

		return -1;

	}

	/* Setup bind mounts for config files in /etc */

	bind_etc(name);

	return 0;

}

int netns_get_fd(const char *name)

{

	char pathbuf[PATH_MAX];

	const char *path, *ptr;

	path = name;

	ptr = strchr(name, '/');

	if (!ptr) {

		snprintf(pathbuf, sizeof(pathbuf), "%s/%s",

			NETNS_RUN_DIR, name );

		path = pathbuf;

	}

	return open(path, O_RDONLY);

}

int netns_foreach(int (*func)(char *nsname, void *arg), void *arg)

{

	DIR *dir;

	struct dirent *entry;

	dir = opendir(NETNS_RUN_DIR);

	if (!dir)

		return -1;

	while ((entry = readdir(dir)) != NULL) {

		if (strcmp(entry->d_name, ".") == 0)

			continue;

		if (strcmp(entry->d_name, "..") == 0)

			continue;

		if (func(entry->d_name, arg))

			break;

	}

	closedir(dir);

	return 0;

}