1 files changed, 250 insertions, 0 deletions
diff --git a/src/kernel/dnbd3_main.c b/src/kernel/dnbd3_main.c
new file mode 100644
index 0000000..cb42567
--- /dev/null
+++ b/src/kernel/dnbd3_main.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file is part of the Distributed Network Block Device 3
+ *
+ * Copyright(c) 2011-2012 Johann Latocha <johann@latocha.de>
+ *
+ * This file may be licensed under the terms of the
+ * GNU General Public License Version 2 (the ``GPL'').
+ *
+ * Software distributed under the License is distributed
+ * on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
+ * express or implied. See the GPL for the specific language
+ * governing rights and limitations.
+ *
+ * You should have received a copy of the GPL along with this
+ * program. If not, go to http://www.gnu.org/licenses/gpl.html
+ * or write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <dnbd3/config/client.h>
+#include <dnbd3/version.h>
+#include <net/ipv6.h>
+#include "dnbd3_main.h"
+#include "blk.h"
+
+int major;
+static unsigned int max_devs = NUMBER_DEVICES;
+static dnbd3_device_t *dnbd3_devices;
+
+struct device *dnbd3_device_to_dev(dnbd3_device_t *dev)
+{
+	return disk_to_dev(dev->disk);
+}
+
+int dnbd3_host_to_sockaddr(const dnbd3_host_t *host, struct sockaddr_storage *dest)
+{
+	struct sockaddr_in *sin4;
+	struct sockaddr_in6 *sin6;
+
+	memset(dest, 0, sizeof(*dest));
+	if (host->type == HOST_IP4) {
+		sin4 = (struct sockaddr_in *)dest;
+		sin4->sin_family = AF_INET;
+		memcpy(&(sin4->sin_addr), host->addr, 4);
+		sin4->sin_port = host->port;
+	} else if (host->type == HOST_IP6) {
+		sin6 = (struct sockaddr_in6 *)dest;
+		sin6->sin6_family = AF_INET6;
+		memcpy(&(sin6->sin6_addr), host->addr, 16);
+		sin6->sin6_port = host->port;
+	} else
+		return 0;
+	return 1;
+}
+
+int is_same_server(const struct sockaddr_storage *const x, const struct sockaddr_storage *const y)
+{
+	if (x->ss_family != y->ss_family)
+		return 0;
+	switch (x->ss_family) {
+	case AF_INET: {
+		const struct sockaddr_in *sinx = (const struct sockaddr_in *)x;
+		const struct sockaddr_in *siny = (const struct sockaddr_in *)y;
+
+		if (sinx->sin_port != siny->sin_port)
+			return 0;
+		if (sinx->sin_addr.s_addr != siny->sin_addr.s_addr)
+			return 0;
+		break;
+	}
+	case AF_INET6: {
+		const struct sockaddr_in6 *sinx = (const struct sockaddr_in6 *)x;
+		const struct sockaddr_in6 *siny = (const struct sockaddr_in6 *)y;
+
+		if (sinx->sin6_port != siny->sin6_port)
+			return 0;
+		if (!ipv6_addr_equal(&sinx->sin6_addr, &siny->sin6_addr))
+			return 0;
+		break;
+	}
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+/**
+ * Get a free slot pointer from the alt_servers list. Tries to find an
+ * entirely empty slot first, then looks for a slot with a server that
+ * wasn't reachable recently, finally returns NULL if none of the
+ * conditions match.
+ * The caller has to hold dev->alt_servers_lock.
+ */
+static dnbd3_alt_server_t *get_free_alt_server(dnbd3_device_t *const dev)
+{
+	int i;
+
+	for (i = 0; i < NUMBER_SERVERS; ++i) {
+		if (dev->alt_servers[i].host.ss_family == 0)
+			return &dev->alt_servers[i];
+	}
+	for (i = 0; i < NUMBER_SERVERS; ++i) {
+		if (dev->alt_servers[i].failures > 10)
+			return &dev->alt_servers[i];
+	}
+	return NULL;
+}
+
+dnbd3_alt_server_t *get_existing_alt_from_addr(const struct sockaddr_storage *const addr,
+		dnbd3_device_t *const dev)
+{
+	int i;
+
+	for (i = 0; i < NUMBER_SERVERS; ++i) {
+		if (is_same_server(addr, &dev->alt_servers[i].host))
+			return &dev->alt_servers[i];
+	}
+	return NULL;
+}
+
+/**
+ * Returns pointer to existing entry in alt_servers that matches the given
+ * alt server, or NULL if not found.
+ * The caller has to hold dev->alt_servers_lock.
+ */
+dnbd3_alt_server_t *get_existing_alt_from_host(const dnbd3_host_t *const host, dnbd3_device_t *const dev)
+{
+	struct sockaddr_storage addr;
+
+	if (!dnbd3_host_to_sockaddr(host, &addr))
+		return NULL;
+	return get_existing_alt_from_addr(&addr, dev);
+}
+
+int dnbd3_add_server(dnbd3_device_t *dev, dnbd3_host_t *host)
+{
+	int result;
+	dnbd3_alt_server_t *alt_server;
+
+	if (host->type != HOST_IP4 && host->type != HOST_IP6)
+		return -EINVAL;
+
+	/* protect access to 'alt_servers' */
+	mutex_lock(&dev->alt_servers_lock);
+	alt_server = get_existing_alt_from_host(host, dev);
+	// ADD
+	if (alt_server != NULL) {
+		// Exists
+		result = -EEXIST;
+	} else {
+		// OK add
+		alt_server = get_free_alt_server(dev);
+		if (alt_server == NULL) {
+			result = -ENOSPC;
+		} else {
+			dnbd3_host_to_sockaddr(host, &alt_server->host);
+			alt_server->protocol_version = 0;
+			alt_server->rtts[0] = alt_server->rtts[1] = alt_server->rtts[2]
+				= alt_server->rtts[3] = RTT_UNREACHABLE;
+			alt_server->failures = 0;
+			alt_server->best_count = 0;
+			result = 0;
+		}
+	}
+	mutex_unlock(&dev->alt_servers_lock);
+	return result;
+}
+
+int dnbd3_rem_server(dnbd3_device_t *dev, dnbd3_host_t *host)
+{
+	dnbd3_alt_server_t *alt_server;
+	int result;
+
+	/* protect access to 'alt_servers' */
+	mutex_lock(&dev->alt_servers_lock);
+	alt_server = get_existing_alt_from_host(host, dev);
+	// REMOVE
+	if (alt_server == NULL) {
+		// Not found
+		result = -ENOENT;
+	} else {
+		// Remove
+		alt_server->host.ss_family = 0;
+		result = 0;
+	}
+	mutex_unlock(&dev->alt_servers_lock);
+	return result;
+}
+
+static int __init dnbd3_init(void)
+{
+	int i;
+
+	dnbd3_devices = kcalloc(max_devs, sizeof(*dnbd3_devices), GFP_KERNEL);
+	if (!dnbd3_devices)
+		return -ENOMEM;
+
+	// initialize block device
+	major = register_blkdev(0, "dnbd3");
+	if (major == 0) {
+		pr_err("register_blkdev failed\n");
+		return -EIO;
+	}
+
+	pr_info("kernel module in version %s loaded\n", DNBD3_VERSION);
+	pr_debug("machine type %s\n", DNBD3_ENDIAN_MODE);
+
+	// add MAX_NUMBER_DEVICES devices
+	for (i = 0; i < max_devs; i++) {
+		if (dnbd3_blk_add_device(&dnbd3_devices[i], i) != 0) {
+			pr_err("dnbd3_blk_add_device failed\n");
+			// TODO: delete all devices added so far.
+			// It could happen that it's not the first one that fails.
+			// Also call unregister_blkdev and free memory.
+			return -EIO;
+		}
+	}
+
+	pr_info("init successful (%i devices)\n", max_devs);
+
+	return 0;
+}
+
+static void __exit dnbd3_exit(void)
+{
+	int i;
+
+	pr_debug("exiting kernel module...\n");
+	for (i = 0; i < max_devs; i++)
+		dnbd3_blk_del_device(&dnbd3_devices[i]);
+
+	unregister_blkdev(major, "dnbd3");
+	kfree(dnbd3_devices);
+
+	pr_info("exit kernel module done\n");
+}
+
+module_init(dnbd3_init);
+module_exit(dnbd3_exit);
+
+MODULE_DESCRIPTION("Distributed Network Block Device 3");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DNBD3_VERSION);
+
+module_param(max_devs, int, 0444);
+MODULE_PARM_DESC(max_devs, "number of network block devices to initialize (default: 8)");