From f9ec2db3b4d1e0047087393218618cf8c439c336 Mon Sep 17 00:00:00 2001
From: Frederic Robra
Date: Sun, 7 Jul 2019 22:13:01 +0200
Subject: added first draft for keepalive and discovery

---
 src/kernel/net.c | 528 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 528 insertions(+)
 create mode 100644 src/kernel/net.c

(limited to 'src/kernel/net.c')

diff --git a/src/kernel/net.c b/src/kernel/net.c
new file mode 100644
index 0000000..f44925f
--- /dev/null
+++ b/src/kernel/net.c
@@ -0,0 +1,528 @@
+/*
+ * This file is part of the Distributed Network Block Device 3
+ *
+ * Copyright(c) 2019 Frederic Robra <frederic@robra.org>
+ * Parts copyright 2011-2012 Johann Latocha <johann@latocha.de>
+ *
+ * This file may be licensed under the terms of 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.
+ *
+ */
+
+
+
+#include <net/sock.h>
+
+#include "dnbd3.h"
+#include "clientconfig.h"
+
+#define dnbd3_cmd_to_priv(req, cmd)   (req)->cmd_flags = REQ_OP_DRV_IN | ((cmd) << REQ_FLAG_BITS)
+#define dnbd3_priv_to_cmd(req)        ((req)->cmd_flags >> REQ_FLAG_BITS)
+#define dnbd3_req_op(req)             req_op(req)
+#define dnbd3_sock_create(af,type,proto,sock) sock_create_kern(&init_net, (af) == HOST_IP4 ? AF_INET : AF_INET6, type, proto, sock)
+
+#define KEEPALIVE_TIMER (TIMER_INTERVAL_KEEPALIVE_PACKET * (jiffies + HZ))
+#define DISCOVERY_TIMER (TIMER_INTERVAL_PROBE_NORMAL * (jiffies + HZ))
+
+#define init_msghdr(h) do { \
+        h.msg_name = NULL; \
+        h.msg_namelen = 0; \
+        h.msg_control = NULL; \
+        h.msg_controllen = 0; \
+        h.msg_flags = MSG_WAITALL | MSG_NOSIGNAL; \
+	} while (0)
+
+
+static void printHost(struct dnbd3_host_t *host, char *msg)
+{
+	if (host->type == HOST_IP4) {
+		printk(KERN_INFO "dnbd3: %s %pI4:%d\n", msg, host->addr, host->port);
+	} else {
+		printk(KERN_INFO "dnbd3: %s [%pI6]:%d\n", msg, host->addr, host->port);
+	}
+}
+
+static void printServerList(struct dnbd3_device *dev)
+{
+	int i;
+	printHost(&dev->initial_server.host, "initial server is");
+	for (i = 0; i < NUMBER_SERVERS; i++) {
+		if (dev->alt_servers[i].host.addr[0] != 0) {
+			printHost(&dev->alt_servers[i].host, "alternative server is");
+		}
+	}
+}
+
+int dnbd3_send_request(struct dnbd3_device *dev, struct dnbd3_sock *sock, struct request *req)
+{
+	dnbd3_request_t dnbd3_request;
+	dnbd3_reply_t dnbd3_reply;
+	struct msghdr msg;
+	struct kvec iov;
+	struct req_iterator iter;
+	struct bio_vec bvec_inst;
+	struct bio_vec *bvec = &bvec_inst;
+	sigset_t blocked, oldset;
+	void *kaddr;
+	int result, count, remaining;
+	uint16_t rid;
+	sock->pending = req;
+	init_msghdr(msg);
+
+	dnbd3_request.magic = dnbd3_packet_magic;
+
+	switch (req_op(req)) {
+//	case REQ_OP_DISCARD:
+//		printk(KERN_DEBUG "dnbd3: request operation discard on device %d\n", dev->minor);
+//		break;
+//	case REQ_OP_FLUSH:
+//		printk(KERN_DEBUG "dnbd3: request operation flush on device %d\n", dev->minor);
+//		break;
+//	case REQ_OP_WRITE:
+//		printk(KERN_DEBUG "dnbd3: request operation write on device %d\n", dev->minor);
+//		break;
+	case REQ_OP_READ:
+		printk(KERN_DEBUG "dnbd3: request operation read\n");
+		dnbd3_request.cmd = CMD_GET_BLOCK;
+		dnbd3_request.offset = blk_rq_pos(req) << 9; // *512
+		dnbd3_request.size = blk_rq_bytes(req); // bytes left to complete entire request
+		break;
+	case REQ_OP_DRV_IN:
+		printk(KERN_DEBUG "dnbd3: request operation driver in\n");
+		dnbd3_request.cmd = dnbd3_priv_to_cmd(req);
+		dnbd3_request.size = 0;
+		break;
+
+	default:
+		return -EIO;
+	}
+
+	dnbd3_request.handle = (uint64_t)(uintptr_t)req; // Double cast to prevent warning on 32bit
+	fixup_request(dnbd3_request);
+	iov.iov_base = &dnbd3_request;
+	iov.iov_len = sizeof(dnbd3_request);
+	if (kernel_sendmsg(sock->sock, &msg, &iov, 1, sizeof(dnbd3_request)) != sizeof(dnbd3_request)) {
+		printk(KERN_ERR "dnbd3: connection to server lost\n");
+		result = -EIO;
+		goto error;
+	}
+
+	// receive net reply
+	iov.iov_base = &dnbd3_reply;
+	iov.iov_len = sizeof(dnbd3_reply);
+	result = kernel_recvmsg(sock->sock, &msg, &iov, 1, sizeof(dnbd3_reply), msg.msg_flags);
+	if (!result) {
+		printk(KERN_ERR "dnbd3: connection to server lost\n");
+		result = -EIO;
+		goto error;
+
+	}
+	fixup_reply(dnbd3_reply);
+
+	// check error
+	if (dnbd3_reply.magic != dnbd3_packet_magic) {
+		printk(KERN_ERR "dnbd3: wrong magic packet\n");
+		result = -EIO;
+		goto error;
+	}
+
+	if (dnbd3_reply.cmd == 0) {
+		printk(KERN_ERR "dnbd3: command was 0\n");
+		result = -EIO;
+		goto error;
+	}
+
+
+	switch (dnbd3_reply.cmd) {
+	case CMD_GET_BLOCK:
+		rq_for_each_segment(bvec_inst, req, iter) {
+			siginitsetinv(&blocked, sigmask(SIGKILL));
+			sigprocmask(SIG_SETMASK, &blocked, &oldset);
+
+			kaddr = kmap(bvec->bv_page) + bvec->bv_offset;
+			iov.iov_base = kaddr;
+			iov.iov_len = bvec->bv_len;
+			if (kernel_recvmsg(sock->sock, &msg, &iov, 1, bvec->bv_len, msg.msg_flags) != bvec->bv_len) {
+				kunmap(bvec->bv_page);
+				sigprocmask(SIG_SETMASK, &oldset, NULL );
+				printk(KERN_ERR "dnbd3: could not receive form net to block layer\n");
+				goto error;
+			}
+			kunmap(bvec->bv_page);
+
+			sigprocmask(SIG_SETMASK, &oldset, NULL );
+		}
+		blk_mq_end_request(req, 0);
+		break;
+	case CMD_GET_SERVERS:
+		printk(KERN_DEBUG "dnbd3: get servers received\n");
+		mutex_lock(&dev->device_lock);
+		if (!dev->use_server_provided_alts) {
+			remaining = dnbd3_reply.size;
+			goto consume_payload;
+		}
+		dev->new_servers_num = 0;
+		count = MIN(NUMBER_SERVERS, dnbd3_reply.size / sizeof(dnbd3_server_entry_t));
+
+		if (count != 0) {
+			iov.iov_base = dev->new_servers;
+			iov.iov_len = count * sizeof(dnbd3_server_entry_t);
+			if (kernel_recvmsg(sock->sock, &msg, &iov, 1, (count * sizeof(dnbd3_server_entry_t)), msg.msg_flags) != (count * sizeof(dnbd3_server_entry_t))) {
+				printk(KERN_ERR "dnbd3: failed to get servers\n");
+				mutex_unlock(&dev->device_lock);
+				goto error;
+			}
+			dev->new_servers_num = count;
+		}
+		// If there were more servers than accepted, remove the remaining data from the socket buffer
+		remaining = dnbd3_reply.size - (count * sizeof(dnbd3_server_entry_t));
+consume_payload:
+		while (remaining > 0) {
+			count = MIN(sizeof(dnbd3_reply), remaining); // Abuse the reply struct as the receive buffer
+			iov.iov_base = &dnbd3_reply;
+			iov.iov_len = count;
+			result = kernel_recvmsg(sock->sock, &msg, &iov, 1, iov.iov_len, msg.msg_flags);
+			if (result <= 0) {
+				printk(KERN_ERR "dnbd3: failed to receive payload from get servers\n");
+				mutex_unlock(&dev->device_lock);
+				goto error;
+			}
+			result = 0;
+		}
+		mutex_unlock(&dev->device_lock);
+		break;
+	case CMD_LATEST_RID:
+		if (dnbd3_reply.size != 2) {
+			printk(KERN_ERR "dnbd3: failed to get latest rid, wrong size\n");
+			goto error;
+		}
+		printk(KERN_DEBUG "dnbd3: latest rid received\n");
+		iov.iov_base = &rid;
+		iov.iov_len = sizeof(rid);
+		if (kernel_recvmsg(sock->sock, &msg, &iov, 1, iov.iov_len, msg.msg_flags) <= 0) {
+			printk(KERN_ERR "dnbd3: failed to get latest rid\n");
+			goto error;
+		}
+		rid = net_order_16(rid);
+		printk("Latest rid of %s is %d (currently using %d)\n", dev->imgname, (int)rid, (int)dev->rid);
+		dev->update_available = (rid > dev->rid ? 1 : 0);
+		break;
+	case CMD_KEEPALIVE:
+		if (dnbd3_reply.size != 0) {
+			printk(KERN_ERR "dnbd3: got keep alive packet with payload\n");
+			goto error;
+		}
+		printk(KERN_DEBUG "dnbd3: keep alive received\n");
+		break;
+
+	default:
+		printk("ERROR: Unknown command (Receive)\n");
+		break;
+
+	}
+	sock->pending = NULL;
+error:
+	return result;
+}
+
+
+void dnbd3_keepalive(struct timer_list *arg)
+{
+	struct dnbd3_sock *sock = container_of(arg, struct dnbd3_sock, keepalive_timer);
+	printk(KERN_DEBUG "dnbd3: schedule keepalive\n");
+//	schedule_work(&sock->keepalive);
+	sock->keepalive_timer.expires = KEEPALIVE_TIMER;
+	add_timer(&sock->keepalive_timer);
+}
+
+static void keepalive(struct work_struct *work)
+{
+	struct dnbd3_sock *sock = container_of(work, struct dnbd3_sock, keepalive);
+	struct request *req;
+	mutex_lock(&sock->lock);
+	req = kmalloc(sizeof(struct request), GFP_ATOMIC );
+	// send keepalive
+	if (req) {
+		dnbd3_cmd_to_priv(req, CMD_KEEPALIVE);
+		dnbd3_send_request(NULL, sock, req); // we do not need the device for keepalive
+		kfree(req);
+	} else {
+		printk(KERN_WARNING "dnbd3: could not create keepalive request\n");
+	}
+	++sock->heartbeat_count;
+	mutex_unlock(&sock->lock);
+}
+
+void dnbd3_discovery(struct timer_list *arg)
+{
+	struct dnbd3_device *dev = container_of(arg, struct dnbd3_device, discovery_timer);
+	printk(KERN_DEBUG "dnbd3: schedule discovery\n");
+//	schedule_work(&dev->discovery);
+	dev->discovery_timer.expires = DISCOVERY_TIMER;
+	add_timer(&dev->discovery_timer);
+}
+
+static void discovery(struct work_struct *work)
+{
+	struct dnbd3_device *dev = container_of(work, struct dnbd3_device, discovery);
+	dnbd3_sock *sock = &dev->socks[0]; // we use the first sock for discovery
+	struct request *req;
+	mutex_lock(&sock->lock);
+	req = kmalloc(sizeof(struct request), GFP_ATOMIC );
+	// send keepalive
+	if (req) {
+		dnbd3_cmd_to_priv(req, CMD_GET_SERVERS);
+		dnbd3_send_request(NULL, sock, req); // we do not need the device for keepalive
+		kfree(req);
+	} else {
+		printk(KERN_WARNING "dnbd3: could not create get servers request\n");
+	}
+	mutex_unlock(&sock->lock);
+}
+
+
+static int dnbd3_socket_connect(dnbd3_device *dev, dnbd3_sock *sock)
+{
+	int result = -EIO;
+	struct request *req1 = NULL;
+	struct timeval timeout;
+	struct dnbd3_server *server = sock->server;
+	dnbd3_request_t dnbd3_request;
+	dnbd3_reply_t dnbd3_reply;
+	struct msghdr msg;
+	struct kvec iov[2];
+	uint16_t rid;
+	uint64_t reported_size;
+	char *name;
+	int mlen;
+	serialized_buffer_t payload_buffer;
+
+	printk(KERN_DEBUG "dnbd3: socket connect device %i\n", dev->minor);
+
+	mutex_init(&sock->lock);
+	mutex_lock(&sock->lock);
+	if (sock->pending) {
+		printk(KERN_DEBUG "dnbd3: socket still in request\n");
+		while (sock->pending)
+			schedule();
+	}
+	if (server->host.port == 0 || server->host.type == 0) {
+		printk(KERN_ERR "dnbd3: host or port not set\n");
+		goto error;
+	}
+	if (sock->sock) {
+		printk(KERN_WARNING "dnbd3: socket already connected\n");
+		goto error;
+	}
+
+	timeout.tv_sec = SOCKET_TIMEOUT_CLIENT_DATA;
+	timeout.tv_usec = 0;
+
+	req1 = kmalloc(sizeof(*req1), GFP_ATOMIC );
+	if (!req1) {
+		printk(KERN_ERR "dnbd3: kmalloc failed\n");
+		goto error;
+	}
+
+	init_msghdr(msg);
+
+	if (dnbd3_sock_create(server->host.type, SOCK_STREAM, IPPROTO_TCP, &sock->sock) < 0) {
+		printk(KERN_ERR "dnbd3: could not create socket\n");
+		goto error;
+	}
+
+	kernel_setsockopt(sock->sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout, sizeof(timeout));
+	kernel_setsockopt(sock->sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(timeout));
+	sock->sock->sk->sk_allocation = GFP_NOIO;
+	if (server->host.type == HOST_IP4) {
+		struct sockaddr_in sin;
+		memset(&sin, 0, sizeof(sin));
+		sin.sin_family = AF_INET;
+		memcpy(&(sin.sin_addr), server->host.addr, 4);
+		sin.sin_port = server->host.port;
+		if (kernel_connect(sock->sock, (struct sockaddr *)&sin, sizeof(sin), 0) != 0) {
+			printk(KERN_ERR "dnbd3: connection to host failed (ipv4)\n");
+			goto error;
+		}
+	} else {
+		struct sockaddr_in6 sin;
+		memset(&sin, 0, sizeof(sin));
+		sin.sin6_family = AF_INET6;
+		memcpy(&(sin.sin6_addr), server->host.addr, 16);
+		sin.sin6_port = server->host.port;
+		if (kernel_connect(sock->sock, (struct sockaddr *)&sin, sizeof(sin), 0) != 0){
+			printk(KERN_ERR "dnbd3: connection to host failed (ipv6)\n");
+			goto error;
+		}
+	}
+	// Request filesize
+	dnbd3_request.magic = dnbd3_packet_magic;
+	dnbd3_request.cmd = CMD_SELECT_IMAGE;
+	iov[0].iov_base = &dnbd3_request;
+	iov[0].iov_len = sizeof(dnbd3_request);
+	serializer_reset_write(&payload_buffer);
+	serializer_put_uint16(&payload_buffer, PROTOCOL_VERSION);
+	serializer_put_string(&payload_buffer, dev->imgname);
+	serializer_put_uint16(&payload_buffer, dev->rid);
+	serializer_put_uint8(&payload_buffer, 0); // is_server = false
+	iov[1].iov_base = &payload_buffer;
+	dnbd3_request.size = iov[1].iov_len = serializer_get_written_length(&payload_buffer);
+	fixup_request(dnbd3_request);
+	mlen = sizeof(dnbd3_request) + iov[1].iov_len;
+	if (kernel_sendmsg(sock->sock, &msg, iov, 2, mlen) != mlen) {
+		printk(KERN_ERR "dnbd3: could not send CMD_SIZE_REQUEST\n");
+		goto error;
+	}
+	// receive reply header
+	iov[0].iov_base = &dnbd3_reply;
+	iov[0].iov_len = sizeof(dnbd3_reply);
+	if (kernel_recvmsg(sock->sock, &msg, iov, 1, sizeof(dnbd3_reply), msg.msg_flags) != sizeof(dnbd3_reply)) {
+		printk(KERN_ERR "dnbd3: received corrupted reply header after CMD_SIZE_REQUEST\n");
+		goto error;
+	}
+
+	// check reply header
+	fixup_reply(dnbd3_reply);
+	if (dnbd3_reply.cmd != CMD_SELECT_IMAGE ||
+			dnbd3_reply.size < 3 ||
+			dnbd3_reply.size > MAX_PAYLOAD ||
+			dnbd3_reply.magic != dnbd3_packet_magic) {
+		printk(KERN_ERR "dnbd3: received invalid reply to CMD_SIZE_REQUEST image does not exist on server\n");
+		goto error;
+	}
+
+	// receive reply payload
+	iov[0].iov_base = &payload_buffer;
+	iov[0].iov_len = dnbd3_reply.size;
+	if (kernel_recvmsg(sock->sock, &msg, iov, 1, dnbd3_reply.size, msg.msg_flags) != dnbd3_reply.size) {
+		printk(KERN_ERR "dnbd3: could not read CMD_SELECT_IMAGE payload on handshake\n");
+		goto error;
+	}
+
+	// handle/check reply payload
+	serializer_reset_read(&payload_buffer, dnbd3_reply.size);
+	server->protocol_version = serializer_get_uint16(&payload_buffer);
+	if (server->protocol_version < MIN_SUPPORTED_SERVER) {
+		printk(KERN_ERR "dnbd3: server version is lower than min supported version\n");
+		goto error;
+	}
+
+	name = serializer_get_string(&payload_buffer);
+	rid = serializer_get_uint16(&payload_buffer);
+	if (dev->rid != rid && strcmp(name, dev->imgname) != 0) {
+		printk(KERN_ERR "dnbd3: server offers image '%s', requested '%s'\n", name, dev->imgname);
+		goto error;
+	}
+
+	reported_size = serializer_get_uint64(&payload_buffer);
+	if (dev->reported_size == NULL) {
+		if (reported_size < 4096) {
+			printk(KERN_ERR "dnbd3: reported size by server is < 4096\n");
+			goto error;
+		}
+		dev->reported_size = reported_size;
+		set_capacity(dev->disk, dev->reported_size >> 9); /* 512 Byte blocks */
+	} else if (dev->reported_size != reported_size) {
+		printk(KERN_ERR "dnbd3: reported size by server is %llu but should be %llu\n", reported_size, dev->reported_size);
+	}
+
+	printk(KERN_DEBUG "dnbd3: connected to image %s, filesize %llu\n", dev->imgname, dev->reported_size);
+
+//	TODO add heartbeat
+	// add heartbeat timer and scheduler for the command
+	INIT_WORK(&sock->keepalive, keepalive);
+	sock->heartbeat_count = 0;
+	timer_setup(&sock->keepalive_timer, dnbd3_keepalive, 0);
+	sock->keepalive_timer.expires = KEEPALIVE_TIMER;
+	add_timer(&sock->keepalive_timer);
+
+	mutex_unlock(&sock->lock);
+
+	return 0;
+error:
+	if (sock->sock) {
+		sock_release(sock->sock);
+		sock->sock = NULL;
+	}
+	if (req1) {
+		kfree(req1);
+	}
+	mutex_unlock(&sock->lock);
+	return result;
+}
+
+static int dnbd3_socket_disconnect(dnbd3_device *dev, dnbd3_sock *sock)
+{
+	printk(KERN_DEBUG "dnbd3: socket disconnect device %i\n", dev->minor);
+	mutex_lock(&sock->lock);
+
+	// clear heartbeat timer
+	del_timer_sync(&sock->keepalive_timer);
+//	destroy_workqueue(&sock->keepalive);
+
+	if (sock->sock) {
+		kernel_sock_shutdown(sock->sock, SHUT_RDWR);
+	}
+
+	// clear socket
+	if (sock->sock) {
+		sock_release(sock->sock);
+		sock->sock = NULL;
+	}
+
+	mutex_unlock(&sock->lock);
+	mutex_destroy(&sock->lock);
+	return 0;
+}
+
+int dnbd3_net_disconnect(struct dnbd3_device *dev)
+{
+	int i;
+	int result;
+	del_timer_sync(&dev->discovery_timer);
+//	destroy_workqueue(&dev->discovery);
+	for (i = 0; i < NUMBER_CONNECTIONS; i++) {
+		if (dev->socks[i].sock) {
+			if (dnbd3_socket_disconnect(dev, &dev->socks[i])) {
+				result = -EIO;
+			}
+		}
+	}
+	return result;
+}
+
+
+int dnbd3_net_connect(struct dnbd3_device *dev) {
+	// TODO decide which socket to connect
+	int result;
+	dev->socks[0].server = &dev->initial_server;
+	if (dnbd3_socket_connect(dev, &dev->socks[0]) == 0) {
+		printServerList(dev);
+
+		INIT_WORK(&dev->discovery, discovery);
+		timer_setup(&dev->discovery_timer, dnbd3_discovery, 0);
+		dev->discovery_timer.expires = DISCOVERY_TIMER;
+		add_timer(&dev->discovery_timer);
+
+		result = 0;
+	} else {
+		printk(KERN_ERR "dnbd3: failed to connect to initial server\n");
+		result = -ENOENT;
+		dev->imgname = NULL;
+		dev->socks[0].server = NULL;
+	}
+	return result;
+}
+
+
+
-- 
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