/*
 * block.c
 *
 *  Created on: Jun 26, 2019
 *      Author: fred
 */

#include <net/sock.h>

#include "dnbd3.h"
#include "block.h"
#include "clientconfig.h"

#define dnbd3_sock_create(af,type,proto,sock) sock_create_kern(&init_net, (af) == HOST_IP4 ? AF_INET : AF_INET6, type, proto, sock)

#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 int dnbd3_open(struct block_device *bdev, fmode_t mode)
{
	dnbd3_device_t *dev = bdev->bd_disk->private_data;
	printk(KERN_DEBUG "dnbd3: open device %i\n", dev->minor);
	//TODO can be removed?
	return 0;
}

static void dnbd3_release(struct gendisk *disk, fmode_t mode)
{
	dnbd3_device_t *dev = disk->private_data;
	printk(KERN_DEBUG "dnbd3: release device %i\n", dev->minor);
	//TODO can be removed?

}


void dnbd3_blk_fail_all_requests(dnbd3_device_t *dev)
{
	printk(KERN_DEBUG "dnbd3: fail all requests device %i\n", dev->minor);
}



int dnbd3_net_connect(dnbd3_device_t *dev)
{
	struct request *req1 = NULL;
	struct timeval timeout;

	printk(KERN_DEBUG "dnbd3: net connect device %i\n", dev->minor);

	if (dev->disconnecting) {
		printk(KERN_DEBUG "dnbd3: device still disconnecting\n");
		while (dev->disconnecting)
			schedule();
	}
	if (dev->request) {
		printk(KERN_DEBUG "dnbd3: device still in request\n");
		while (dev->disconnecting)
			schedule();
	}

	timeout.tv_sec = SOCKET_TIMEOUT_CLIENT_DATA;
	timeout.tv_usec = 0;

	// do some checks before connecting

	req1 = kmalloc(sizeof(*req1), GFP_ATOMIC );
	if (!req1) {
		printk(KERN_ERR "dnbd3: kmalloc failed\n");
		goto error;
	}
	if (dev->cur_server.host.port == 0 || dev->cur_server.host.type == 0 || dev->imgname == NULL ) {
		printk(KERN_ERR "dnbd3: host, port or image name not set\n");
		goto error;
	}
	if (dev->sock) {
		printk(KERN_WARNING "dnbd3: already connected\n");
		goto error;
	}

	if (dev->cur_server.host.type != HOST_IP4 && dev->cur_server.host.type != HOST_IP6) {
		printk(KERN_ERR "dnbd3: unknown address type %d\n", (int)dev->cur_server.host.type);
		goto error;
	}

	if (dev->better_sock == NULL ) {
		//  no established connection yet from discovery thread, start new one
		dnbd3_request_t dnbd3_request;
		dnbd3_reply_t dnbd3_reply;
		struct msghdr msg;
		struct kvec iov[2];
		uint16_t rid;
		char *name;
		int mlen;
		init_msghdr(msg);

		if (dnbd3_sock_create(dev->cur_server.host.type, SOCK_STREAM, IPPROTO_TCP, &dev->sock) < 0) {
			printk(KERN_ERR "dnbd3: could not create socket\n");
			goto error;
		}

		kernel_setsockopt(dev->sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout, sizeof(timeout));
		kernel_setsockopt(dev->sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(timeout));
		dev->sock->sk->sk_allocation = GFP_NOIO;
		if (dev->cur_server.host.type == HOST_IP4) {
			struct sockaddr_in sin;
			memset(&sin, 0, sizeof(sin));
			sin.sin_family = AF_INET;
			memcpy(&(sin.sin_addr), dev->cur_server.host.addr, 4);
			sin.sin_port = dev->cur_server.host.port;
			if (kernel_connect(dev->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), dev->cur_server.host.addr, 16);
			sin.sin6_port = dev->cur_server.host.port;
			if (kernel_connect(dev->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(&dev->payload_buffer);
		serializer_put_uint16(&dev->payload_buffer, PROTOCOL_VERSION);
		serializer_put_string(&dev->payload_buffer, dev->imgname);
		serializer_put_uint16(&dev->payload_buffer, dev->rid);
		serializer_put_uint8(&dev->payload_buffer, 0); // is_server = false
		iov[1].iov_base = &dev->payload_buffer;
		dnbd3_request.size = iov[1].iov_len = serializer_get_written_length(&dev->payload_buffer);
		fixup_request(dnbd3_request);
		mlen = sizeof(dnbd3_request) + iov[1].iov_len;
		if (kernel_sendmsg(dev->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(dev->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 = &dev->payload_buffer;
		iov[0].iov_len = dnbd3_reply.size;
		if (kernel_recvmsg(dev->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(&dev->payload_buffer, dnbd3_reply.size);
		dev->cur_server.protocol_version = serializer_get_uint16(&dev->payload_buffer);
		if (dev->cur_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(&dev->payload_buffer);
		if (dev->rid != 0 && strcmp(name, dev->imgname) != 0) {
			printk(KERN_ERR "dnbd3: server offers image '%s', requested '%s'\n", name, dev->imgname);
			goto error;
		}

		if (strlen(dev->imgname) < strlen(name)) {
			dev->imgname = krealloc(dev->imgname, strlen(name) + 1, GFP_ATOMIC );
			if (dev->imgname == NULL ) {
				printk(KERN_ERR "dnbd3: reallocating buffer for new image name failed\n");
				goto error;
			}
		}
		strcpy(dev->imgname, name);
		rid = serializer_get_uint16(&dev->payload_buffer);
		if (dev->rid != 0 && dev->rid != rid) {
			printk(KERN_ERR "dnbd3: server provides rid %d, requested was %d\n", (int)rid, (int)dev->rid);
			goto error;
		}

		dev->rid = rid;
		dev->reported_size = serializer_get_uint64(&dev->payload_buffer);
		if (dev->reported_size < 4096) {
			printk(KERN_ERR "dnbd3: reported size by server is < 4096\n");
			goto error;
		}

		// store image information
		set_capacity(dev->disk, dev->reported_size >> 9); /* 512 Byte blocks */
		printk(KERN_DEBUG "dnbd3: connected to image %s, filesize %llu\n", dev->imgname, dev->reported_size);
		dev->update_available = 0;
	} else { // Switching server, connection is already established and size request was executed

		printk(KERN_DEBUG "dnbd3: changing server\n");
		dev->sock = dev->better_sock;
		dev->better_sock = NULL;
		kernel_setsockopt(dev->sock, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout, sizeof(timeout));
		kernel_setsockopt(dev->sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout, sizeof(timeout));
	}

	dev->panic = 0;
	dev->panic_count = 0;

	// Enqueue request to request_queue_send for a fresh list of alt servers
	//TODO refresh alt server list

	// add heartbeat timer
	//TODO needed anymore=
//	dev->heartbeat_count = 0;
//	timer_setup(&dev->hb_timer, dnbd3_net_heartbeat, 0);
//	dev->hb_timer.expires = jiffies + HZ;
//	add_timer(&dev->hb_timer);
	return 0;
error:
	if (dev->sock) {
		sock_release(dev->sock);
		dev->sock = NULL;
	}
	dev->cur_server.host.type = 0;
	dev->cur_server.host.port = 0;
	if (req1) {
		kfree(req1);
	}
	return -1;
}


int dnbd3_net_disconnect(dnbd3_device_t *dev)
{
	printk(KERN_DEBUG "dnbd3: net disconnect device %i\n", dev->minor);
	if (dev->disconnecting)  {
		return 0;
	}

	dev->disconnecting = 1;

	// clear heartbeat timer
//	del_timer(&dev->hb_timer);

	dev->discover = 0;

	if (dev->sock) {
		kernel_sock_shutdown(dev->sock, SHUT_RDWR);
	}

	// clear socket
	if (dev->sock) {
		sock_release(dev->sock);
		dev->sock = NULL;
	}
	dev->cur_server.host.type = 0;
	dev->cur_server.host.port = 0;

	dev->disconnecting = 0;

	return 0;
}

static int dnbd3_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
{
	int result = -100;
	dnbd3_device_t *dev = bdev->bd_disk->private_data;
	char *imgname = NULL;
	dnbd3_ioctl_t *msg = NULL;

	printk(KERN_DEBUG "dnbd3: ioctl device %i, cmd %i, arg %lu\n", dev->minor, cmd, arg);
	//unsigned long irqflags;

	while (dev->disconnecting) {
		// do nothing
	}

	if (arg != 0) {
		msg = kmalloc(sizeof(*msg), GFP_KERNEL);
		if (msg == NULL) return -ENOMEM;
		if (copy_from_user((char *)msg, (char *)arg, 2) != 0 || msg->len != sizeof(*msg)) {
			result = -ENOEXEC;
			goto cleanup_return;
		}
		if (copy_from_user((char *)msg, (char *)arg, sizeof(*msg)) != 0) {
			result = -ENOENT;
			goto cleanup_return;
		}
		if (msg->imgname != NULL && msg->imgnamelen > 0) {
			imgname = kmalloc(msg->imgnamelen + 1, GFP_KERNEL);
			if (imgname == NULL) {
				result = -ENOMEM;
				goto cleanup_return;
			}
			if (copy_from_user(imgname, msg->imgname, msg->imgnamelen) != 0) {
				result = -ENOENT;
				goto cleanup_return;
			}
			imgname[msg->imgnamelen] = '\0';

			printk(KERN_DEBUG "dnbd3: ioctl image name of len %i is %s\n", (int)msg->imgnamelen, imgname);
		}
	}

	switch (cmd) {
	case IOCTL_OPEN:
		printk(KERN_DEBUG "dnbd3: ioctl open\n");
		if (dev->imgname != NULL) {
			result = -EBUSY;
		} else if (imgname == NULL) {
			result = -EINVAL;
		} else if (msg == NULL) {
			result = -EINVAL;
		} else {
			if (sizeof(msg->host) != sizeof(dev->cur_server.host)) {
				printk(KERN_INFO "dnbd3: odd size bug#1 triggered in ioctl\n");
			}
			memcpy(&dev->cur_server.host, &msg->host, sizeof(msg->host));
			dev->cur_server.failures = 0;
			memcpy(&dev->initial_server, &dev->cur_server, sizeof(dev->initial_server));
			dev->imgname = imgname;
			dev->rid = msg->rid;
			dev->use_server_provided_alts = msg->use_server_provided_alts;
			// Forget all alt servers on explicit connect, set first al server to initial server
			memset(dev->alt_servers, 0, sizeof(dev->alt_servers[0])*NUMBER_SERVERS);
			memcpy(dev->alt_servers, &dev->initial_server, sizeof(dev->alt_servers[0]));
//#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
//			if (blk_queue->backing_dev_info != NULL) {
//				blk_queue->backing_dev_info->ra_pages = (msg->read_ahead_kb * 1024) / PAGE_SIZE;
//			}
//#else
//			blk_queue->backing_dev_info.ra_pages = (msg->read_ahead_kb * 1024) / PAGE_SIZE;
//#endif
			if (dnbd3_net_connect(dev) == 0) {
				result = 0;
				imgname = NULL; // Prevent kfree at the end
			} else {
				result = -ENOENT;
				dev->imgname = NULL;
			}
		}
		break;

	case IOCTL_CLOSE:
		printk(KERN_DEBUG "dnbd3: ioctl close\n");
		dnbd3_blk_fail_all_requests(dev);
		result = dnbd3_net_disconnect(dev);
		dnbd3_blk_fail_all_requests(dev);
		set_capacity(dev->disk, 0);
		if (dev->imgname) {
			kfree(dev->imgname);
			dev->imgname = NULL;
		}
		break;

	case IOCTL_SWITCH:
		printk(KERN_DEBUG "dnbd3: ioctl switch\n");
		result = -EINVAL;
		break;

	case IOCTL_ADD_SRV:
	case IOCTL_REM_SRV:
		printk(KERN_DEBUG "dnbd3: ioctl add/rem srv\n");
		if (dev->imgname == NULL) {
			result = -ENOENT;
		} else if (dev->new_servers_num >= NUMBER_SERVERS) {
			result = -EAGAIN;
		} else if (msg == NULL) {
			result = -EINVAL;
		} else {
			memcpy(&dev->new_servers[dev->new_servers_num].host, &msg->host, sizeof(msg->host));
			dev->new_servers[dev->new_servers_num].failures = (cmd == IOCTL_ADD_SRV ? 0 : 1); // 0 = ADD, 1 = REM
			++dev->new_servers_num;
			result = 0;
		}
		break;

	case BLKFLSBUF:
		printk(KERN_DEBUG "dnbd3: ioctl blkflsbuf\n");
		result = 0;
		break;

	default:
		printk(KERN_DEBUG "dnbd3: ioctl unhandled cmd\n");
		result = -EIO;
		break;
	}

cleanup_return:
	if (msg) kfree(msg);
	if (imgname) kfree(imgname);
	return result;

}



struct block_device_operations dnbd3_fops =
{
	.owner = THIS_MODULE,
	.open = dnbd3_open,
	.release = dnbd3_release,
	.ioctl = dnbd3_ioctl,
	.compat_ioctl =	dnbd3_ioctl,
};