/*
 * An implementation of key value pair (KVP) functionality for Linux.
 *
 *
 * Copyright (C) 2010, Novell, Inc.
 * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/net.h>
#include <linux/nls.h>
#include <linux/connector.h>
#include <linux/workqueue.h>
#include <linux/hyperv.h>



/*
 * Global state maintained for transaction that is being processed.
 * Note that only one transaction can be active at any point in time.
 *
 * This state is set when we receive a request from the host; we
 * cleanup this state when the transaction is completed - when we respond
 * to the host with the key value.
 */

static struct {
	bool active; /* transaction status - active or not */
	int recv_len; /* number of bytes received. */
	struct hv_kvp_msg  *kvp_msg; /* current message */
	struct vmbus_channel *recv_channel; /* chn we got the request */
	u64 recv_req_id; /* request ID. */
	void *kvp_context; /* for the channel callback */
} kvp_transaction;

/*
 * Before we can accept KVP messages from the host, we need
 * to handshake with the user level daemon. This state tracks
 * if we are in the handshake phase.
 */
static bool in_hand_shake = true;

/*
 * This state maintains the version number registered by the daemon.
 */
static int dm_reg_value;

static void kvp_send_key(struct work_struct *dummy);


static void kvp_respond_to_host(struct hv_kvp_msg *msg, int error);
static void kvp_work_func(struct work_struct *dummy);
static void kvp_register(int);

static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);

static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
static const char kvp_name[] = "kvp_kernel_module";
static u8 *recv_buffer;
/*
 * Register the kernel component with the user-level daemon.
 * As part of this registration, pass the LIC version number.
 */

static void
kvp_register(int reg_value)
{

	struct cn_msg *msg;
	struct hv_kvp_msg *kvp_msg;
	char *version;

	msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg), GFP_ATOMIC);

	if (msg) {
		kvp_msg = (struct hv_kvp_msg *)msg->data;
		version = kvp_msg->body.kvp_register.version;
		msg->id.idx =  CN_KVP_IDX;
		msg->id.val = CN_KVP_VAL;

		kvp_msg->kvp_hdr.operation = reg_value;
		strcpy(version, HV_DRV_VERSION);
		msg->len = sizeof(struct hv_kvp_msg);
		cn_netlink_send(msg, 0, GFP_ATOMIC);
		kfree(msg);
	}
}
static void
kvp_work_func(struct work_struct *dummy)
{
	/*
	 * If the timer fires, the user-mode component has not responded;
	 * process the pending transaction.
	 */
	kvp_respond_to_host(NULL, HV_E_FAIL);
}

static int kvp_handle_handshake(struct hv_kvp_msg *msg)
{
	int ret = 1;

	switch (msg->kvp_hdr.operation) {
	case KVP_OP_REGISTER:
		dm_reg_value = KVP_OP_REGISTER;
		pr_info("KVP: IP injection functionality not available\n");
		pr_info("KVP: Upgrade the KVP daemon\n");
		break;
	case KVP_OP_REGISTER1:
		dm_reg_value = KVP_OP_REGISTER1;
		break;
	default:
		pr_info("KVP: incompatible daemon\n");
		pr_info("KVP: KVP version: %d, Daemon version: %d\n",
			KVP_OP_REGISTER1, msg->kvp_hdr.operation);
		ret = 0;
	}

	if (ret) {
		/*
		 * We have a compatible daemon; complete the handshake.
		 */
		pr_info("KVP: user-mode registering done.\n");
		kvp_register(dm_reg_value);
		kvp_transaction.active = false;
		if (kvp_transaction.kvp_context)
			hv_kvp_onchannelcallback(kvp_transaction.kvp_context);
	}
	return ret;
}


/*
 * Callback when data is received from user mode.
 */

static void
kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
	struct hv_kvp_msg *message;
	struct hv_kvp_msg_enumerate *data;
	int	error = 0;

	message = (struct hv_kvp_msg *)msg->data;

	/*
	 * If we are negotiating the version information
	 * with the daemon; handle that first.
	 */

	if (in_hand_shake) {
		if (kvp_handle_handshake(message))
			in_hand_shake = false;
		return;
	}

	/*
	 * Based on the version of the daemon, we propagate errors from the
	 * daemon differently.
	 */

	data = &message->body.kvp_enum_data;

	switch (dm_reg_value) {
	case KVP_OP_REGISTER:
		/*
		 * Null string is used to pass back error condition.
		 */
		if (data->data.key[0] == 0)
			error = HV_S_CONT;
		break;

	case KVP_OP_REGISTER1:
		/*
		 * We use the message header information from
		 * the user level daemon to transmit errors.
		 */
		error = message->error;
		break;
	}

	/*
	 * Complete the transaction by forwarding the key value
	 * to the host. But first, cancel the timeout.
	 */
	if (cancel_delayed_work_sync(&kvp_work))
		kvp_respond_to_host(message, error);
}


static int process_ob_ipinfo(void *in_msg, void *out_msg, int op)
{
	struct hv_kvp_msg *in = in_msg;
	struct hv_kvp_ip_msg *out = out_msg;
	int len;

	switch (op) {
	case KVP_OP_GET_IP_INFO:
		/*
		 * Transform all parameters into utf16 encoding.
		 */
		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.ip_addr,
				strlen((char *)in->body.kvp_ip_val.ip_addr),
				UTF16_HOST_ENDIAN,
				(wchar_t *)out->kvp_ip_val.ip_addr,
				MAX_IP_ADDR_SIZE);
		if (len < 0)
			return len;

		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.sub_net,
				strlen((char *)in->body.kvp_ip_val.sub_net),
				UTF16_HOST_ENDIAN,
				(wchar_t *)out->kvp_ip_val.sub_net,
				MAX_IP_ADDR_SIZE);
		if (len < 0)
			return len;

		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.gate_way,
				strlen((char *)in->body.kvp_ip_val.gate_way),
				UTF16_HOST_ENDIAN,
				(wchar_t *)out->kvp_ip_val.gate_way,
				MAX_GATEWAY_SIZE);
		if (len < 0)
			return len;

		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.dns_addr,
				strlen((char *)in->body.kvp_ip_val.dns_addr),
				UTF16_HOST_ENDIAN,
				(wchar_t *)out->kvp_ip_val.dns_addr,
				MAX_IP_ADDR_SIZE);
		if (len < 0)
			return len;

		len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.adapter_id,
				strlen((char *)in->body.kvp_ip_val.adapter_id),
				UTF16_HOST_ENDIAN,
				(wchar_t *)out->kvp_ip_val.adapter_id,
				MAX_IP_ADDR_SIZE);
		if (len < 0)
			return len;

		out->kvp_ip_val.dhcp_enabled =
			in->body.kvp_ip_val.dhcp_enabled;
		out->kvp_ip_val.addr_family =
			in->body.kvp_ip_val.addr_family;
	}

	return 0;
}

static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
{
	struct hv_kvp_ip_msg *in = in_msg;
	struct hv_kvp_msg *out = out_msg;

	switch (op) {
	case KVP_OP_SET_IP_INFO:
		/*
		 * Transform all parameters into utf8 encoding.
		 */
		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.ip_addr,
				MAX_IP_ADDR_SIZE,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)out->body.kvp_ip_val.ip_addr,
				MAX_IP_ADDR_SIZE);

		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.sub_net,
				MAX_IP_ADDR_SIZE,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)out->body.kvp_ip_val.sub_net,
				MAX_IP_ADDR_SIZE);

		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.gate_way,
				MAX_GATEWAY_SIZE,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)out->body.kvp_ip_val.gate_way,
				MAX_GATEWAY_SIZE);

		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.dns_addr,
				MAX_IP_ADDR_SIZE,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)out->body.kvp_ip_val.dns_addr,
				MAX_IP_ADDR_SIZE);

		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;

	default:
		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
				MAX_ADAPTER_ID_SIZE,
				UTF16_LITTLE_ENDIAN,
				(__u8 *)out->body.kvp_ip_val.adapter_id,
				MAX_ADAPTER_ID_SIZE);

		out->body.kvp_ip_val.addr_family = in->kvp_ip_val.addr_family;
	}
}




static void
kvp_send_key(struct work_struct *dummy)
{
	struct cn_msg *msg;
	struct hv_kvp_msg *message;
	struct hv_kvp_msg *in_msg;
	__u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
	__u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
	__u32 val32;
	__u64 val64;

	msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
	if (!msg)
		return;

	msg->id.idx =  CN_KVP_IDX;
	msg->id.val = CN_KVP_VAL;

	message = (struct hv_kvp_msg *)msg->data;
	message->kvp_hdr.operation = operation;
	message->kvp_hdr.pool = pool;
	in_msg = kvp_transaction.kvp_msg;

	/*
	 * The key/value strings sent from the host are encoded in
	 * in utf16; convert it to utf8 strings.
	 * The host assures us that the utf16 strings will not exceed
	 * the max lengths specified. We will however, reserve room
	 * for the string terminating character - in the utf16s_utf8s()
	 * function we limit the size of the buffer where the converted
	 * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to gaurantee
	 * that the strings can be properly terminated!
	 */

	switch (message->kvp_hdr.operation) {
	case KVP_OP_SET_IP_INFO:
		process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
		break;
	case KVP_OP_GET_IP_INFO:
		process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
		break;
	case KVP_OP_SET:
		switch (in_msg->body.kvp_set.data.value_type) {
		case REG_SZ:
			/*
			 * The value is a string - utf16 encoding.
			 */
			message->body.kvp_set.data.value_size =
				utf16s_to_utf8s(
				(wchar_t *)in_msg->body.kvp_set.data.value,
				in_msg->body.kvp_set.data.value_size,
				UTF16_LITTLE_ENDIAN,
				message->body.kvp_set.data.value,
				HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
				break;

		case REG_U32:
			/*
			 * The value is a 32 bit scalar.
			 * We save this as a utf8 string.
			 */
			val32 = in_msg->body.kvp_set.data.value_u32;
			message->body.kvp_set.data.value_size =