/*
 * 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>


/*
 * Pre win8 version numbers used in ws2008 and ws 2008 r2 (win7)
 */
#define WS2008_SRV_MAJOR        1
#define WS2008_SRV_MINOR        0
#define WS2008_SRV_VERSION     (WS2008_SRV_MAJOR << 16 | WS2008_SRV_MINOR)

#define WIN7_SRV_MAJOR   3
#define WIN7_SRV_MINOR   0
#define WIN7_SRV_VERSION     (WIN7_SRV_MAJOR << 16 | WIN7_SRV_MINOR)

#define WIN8_SRV_MAJOR   4
#define WIN8_SRV_MINOR   0
#define WIN8_SRV_VERSION     (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)

/*
 * 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.
 * This number has no meaning, it satisfies the registration protocol.
 */
#define HV_DRV_VERSION           "3.1"

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, 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 void poll_channel(struct vmbus_channel *channel)
{
        if (channel->target_cpu != smp_processor_id())
                smp_call_function_single(channel->target_cpu,
                                         hv_kvp_onchannelcallback,
                                         channel, true);
        else
                hv_kvp_onchannelcallback(channel);
}


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)
                        poll_channel(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;
        int rc;

        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 =
                                sprintf(message->body.kvp_set.data.value,
                                        "%d", val32) + 1;
                        break;

                case REG_U64:
                        /*
                         * The value is a 64 bit scalar.
                         * We save this as a utf8 string.
                         */
                        val64 = in_msg->body.kvp_set.data.value_u64;
                        message->body.kvp_set.data.value_size =
                                sprintf(message->body.kvp_set.data.value,
                                        "%llu", val64) + 1;
                        break;

                }
        case KVP_OP_GET:
                message->body.kvp_set.data.key_size =
                        utf16s_to_utf8s(
                        (wchar_t *)in_msg->body.kvp_set.data.key,
                        in_msg->body.kvp_set.data.key_size,
                        UTF16_LITTLE_ENDIAN,
                        message->body.kvp_set.data.key,
                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
                        break;

        case KVP_OP_DELETE:
                message->body.kvp_delete.key_size =
                        utf16s_to_utf8s(
                        (wchar_t *)in_msg->body.kvp_delete.key,
                        in_msg->body.kvp_delete.key_size,
                        UTF16_LITTLE_ENDIAN,
                        message->body.kvp_delete.key,
                        HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
                        break;

        case KVP_OP_ENUMERATE:
                message->body.kvp_enum_data.index =
                        in_msg->body.kvp_enum_data.index;
                        break;
        }

        msg->len = sizeof(struct hv_kvp_msg);
        rc = cn_netlink_send(msg, 0, 0, GFP_ATOMIC);
        if (rc) {
                pr_debug("KVP: failed to communicate to the daemon: %d\n", rc);
                if (cancel_delayed_work_sync(&kvp_work))
                        kvp_respond_to_host(message, HV_E_FAIL);
        }

        kfree(msg);

        return;
}

/*
 * Send a response back to the host.
 */

static void
kvp_respond_to_host(struct hv_kvp_msg *msg_to_host, int error)
{
        struct hv_kvp_msg  *kvp_msg;
        struct hv_kvp_exchg_msg_value  *kvp_data;
        char    *key_name;
        char    *value;
        struct icmsg_hdr *icmsghdrp;
        int     keylen = 0;
        int     valuelen = 0;
        u32     buf_len;
        struct vmbus_channel *channel;
        u64     req_id;
        int ret;

        /*
         * If a transaction is not active; log and return.
         */

        if (!kvp_transaction.active) {
                /*
                 * This is a spurious call!
                 */
                pr_warn("KVP: Transaction not active\n");
                return;
        }
        /*
         * Copy the global state for completing the transaction. Note that
         * only one transaction can be active at a time.
         */

        buf_len = kvp_transaction.recv_len;
        channel = kvp_transaction.recv_channel;
        req_id = kvp_transaction.recv_req_id;

        kvp_transaction.active = false;

        icmsghdrp = (struct icmsg_hdr *)
                        &recv_buffer[sizeof(struct vmbuspipe_hdr)];

        if (channel->onchannel_callback == NULL)
                /*
                 * We have raced with util driver being unloaded;
                 * silently return.
                 */
                return;

        icmsghdrp->status = error;

        /*
         * If the error parameter is set, terminate the host's enumeration
         * on this pool.
         */
        if (error) {
                /*
                 * Something failed or we have timedout;
                 * terminate the current host-side iteration.
                 */
                goto response_done;
        }

        kvp_msg = (struct hv_kvp_msg *)
                        &recv_buffer[sizeof(struct vmbuspipe_hdr) +
                        sizeof(struct icmsg_hdr)];

        switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
        case KVP_OP_GET_IP_INFO:
                ret = process_ob_ipinfo(msg_to_host,
                                 (struct hv_kvp_ip_msg *)kvp_msg,
                                 KVP_OP_GET_IP_INFO);
                if (ret < 0)
                        icmsghdrp->status = HV_E_FAIL;

                goto response_done;
        case KVP_OP_SET_IP_INFO:
                goto response_done;
        case KVP_OP_GET:
                kvp_data = &kvp_msg->body.kvp_get.data;
                goto copy_value;

        case KVP_OP_SET:
        case KVP_OP_DELETE:
                goto response_done;

        default:
                break;
        }

        kvp_data = &kvp_msg->body.kvp_enum_data.data;
        key_name = msg_to_host->body.kvp_enum_data.data.key;

        /*
         * The windows host expects the key/value pair to be encoded
         * in utf16. Ensure that the key/value size reported to the host
         * will be less than or equal to the MAX size (including the
         * terminating character).
         */
        keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
                                (wchar_t *) kvp_data->key,
                                (HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
        kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */

copy_value:
        value = msg_to_host->body.kvp_enum_data.data.value;
        valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
                                (wchar_t *) kvp_data->value,
                                (HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
        kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */

        /*
         * If the utf8s to utf16s conversion failed; notify host
         * of the error.
         */
        if ((keylen < 0) || (valuelen < 0))
                icmsghdrp->status = HV_E_FAIL;

        kvp_data->value_type = REG_SZ; /* all our values are strings */

response_done:
        icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;

        vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
                                VM_PKT_DATA_INBAND, 0);
        poll_channel(channel);
}

/*
 * This callback is invoked when we get a KVP message from the host.
 * The host ensures that only one KVP transaction can be active at a time.
 * KVP implementation in Linux needs to forward the key to a user-mde
 * component to retrive the corresponding value. Consequently, we cannot
 * respond to the host in the conext of this callback. Since the host
 * guarantees that at most only one transaction can be active at a time,
 * we stash away the transaction state in a set of global variables.
 */

void hv_kvp_onchannelcallback(void *context)
{
        struct vmbus_channel *channel = context;
        u32 recvlen;
        u64 requestid;

        struct hv_kvp_msg *kvp_msg;

        struct icmsg_hdr *icmsghdrp;
        struct icmsg_negotiate *negop = NULL;
        int util_fw_version;
        int kvp_srv_version;

        if (kvp_transaction.active) {
                /*
                 * We will defer processing this callback once
                 * the current transaction is complete.
                 */
                kvp_transaction.kvp_context = context;
                return;
        }

        vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 4, &recvlen,
                         &requestid);

        if (recvlen > 0) {
                icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
                        sizeof(struct vmbuspipe_hdr)];

                if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
                        /*
                         * Based on the host, select appropriate
                         * framework and service versions we will
                         * negotiate.
                         */
                        switch (vmbus_proto_version) {
                        case (VERSION_WS2008):
                                util_fw_version = UTIL_WS2K8_FW_VERSION;
                                kvp_srv_version = WS2008_SRV_VERSION;
                                break;
                        case (VERSION_WIN7):
                                util_fw_version = UTIL_FW_VERSION;
                                kvp_srv_version = WIN7_SRV_VERSION;
                                break;
                        default:
                                util_fw_version = UTIL_FW_VERSION;
                                kvp_srv_version = WIN8_SRV_VERSION;
                        }
                        vmbus_prep_negotiate_resp(icmsghdrp, negop,
                                 recv_buffer, util_fw_version,
                                 kvp_srv_version);

                } else {
                        kvp_msg = (struct hv_kvp_msg *)&recv_buffer[
                                sizeof(struct vmbuspipe_hdr) +
                                sizeof(struct icmsg_hdr)];

                        /*
                         * Stash away this global state for completing the
                         * transaction; note transactions are serialized.
                         */

                        kvp_transaction.recv_len = recvlen;
                        kvp_transaction.recv_channel = channel;
                        kvp_transaction.recv_req_id = requestid;
                        kvp_transaction.active = true;
                        kvp_transaction.kvp_msg = kvp_msg;

                        /*
                         * Get the information from the
                         * user-mode component.
                         * component. This transaction will be
                         * completed when we get the value from
                         * the user-mode component.
                         * Set a timeout to deal with
                         * user-mode not responding.
                         */
                        schedule_work(&kvp_sendkey_work);
                        schedule_delayed_work(&kvp_work, 5*HZ);

                        return;

                }

                icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                        | ICMSGHDRFLAG_RESPONSE;

                vmbus_sendpacket(channel, recv_buffer,
                                       recvlen, requestid,
                                       VM_PKT_DATA_INBAND, 0);
        }

}

int
hv_kvp_init(struct hv_util_service *srv)
{
        int err;

        err = cn_add_callback(&kvp_id, kvp_name, kvp_cn_callback);
        if (err)
                return err;
        recv_buffer = srv->recv_buffer;

        /*
         * When this driver loads, the user level daemon that
         * processes the host requests may not yet be running.
         * Defer processing channel callbacks until the daemon
         * has registered.
         */
        kvp_transaction.active = true;

        return 0;
}

void hv_kvp_deinit(void)
{
        cn_del_callback(&kvp_id);
        cancel_delayed_work_sync(&kvp_work);
        cancel_work_sync(&kvp_sendkey_work);
}