/*
 * 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.
 *
 */


#include <sys/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <sys/utsname.h>
#include <linux/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h>
#include <linux/connector.h>
#include <linux/hyperv.h>
#include <linux/netlink.h>
#include <ifaddrs.h>
#include <netdb.h>
#include <syslog.h>
#include <sys/stat.h>
#include <fcntl.h>

/*
 * KVP protocol: The user mode component first registers with the
 * the kernel component. Subsequently, the kernel component requests, data
 * for the specified keys. In response to this message the user mode component
 * fills in the value corresponding to the specified key. We overload the
 * sequence field in the cn_msg header to define our KVP message types.
 *
 * We use this infrastructure for also supporting queries from user mode
 * application for state that may be maintained in the KVP kernel component.
 *
 */


enum key_index {
        FullyQualifiedDomainName = 0,
        IntegrationServicesVersion, /*This key is serviced in the kernel*/
        NetworkAddressIPv4,
        NetworkAddressIPv6,
        OSBuildNumber,
        OSName,
        OSMajorVersion,
        OSMinorVersion,
        OSVersion,
        ProcessorArchitecture
};

static char kvp_send_buffer[4096];
static char kvp_recv_buffer[4096];
static struct sockaddr_nl addr;

static char *os_name = "";
static char *os_major = "";
static char *os_minor = "";
static char *processor_arch;
static char *os_build;
static char *lic_version;
static struct utsname uts_buf;


#define MAX_FILE_NAME 100
#define ENTRIES_PER_BLOCK 50

struct kvp_record {
        __u8 key[HV_KVP_EXCHANGE_MAX_KEY_SIZE];
        __u8 value[HV_KVP_EXCHANGE_MAX_VALUE_SIZE];
};

struct kvp_file_state {
        int fd;
        int num_blocks;
        struct kvp_record *records;
        int num_records;
        __u8 fname[MAX_FILE_NAME];
};

static struct kvp_file_state kvp_file_info[KVP_POOL_COUNT];

static void kvp_acquire_lock(int pool)
{
        struct flock fl = {F_WRLCK, SEEK_SET, 0, 0, 0};
        fl.l_pid = getpid();

        if (fcntl(kvp_file_info[pool].fd, F_SETLKW, &fl) == -1) {
                syslog(LOG_ERR, "Failed to acquire the lock pool: %d", pool);
                exit(-1);
        }
}

static void kvp_release_lock(int pool)
{
        struct flock fl = {F_UNLCK, SEEK_SET, 0, 0, 0};
        fl.l_pid = getpid();

        if (fcntl(kvp_file_info[pool].fd, F_SETLK, &fl) == -1) {
                perror("fcntl");
                syslog(LOG_ERR, "Failed to release the lock pool: %d", pool);
                exit(-1);
        }
}

static void kvp_update_file(int pool)
{
        FILE *filep;
        size_t bytes_written;

        /*
         * We are going to write our in-memory registry out to
         * disk; acquire the lock first.
         */
        kvp_acquire_lock(pool);

        filep = fopen(kvp_file_info[pool].fname, "w");
        if (!filep) {
                kvp_release_lock(pool);
                syslog(LOG_ERR, "Failed to open file, pool: %d", pool);
                exit(-1);
        }

        bytes_written = fwrite(kvp_file_info[pool].records,
                                sizeof(struct kvp_record),
                                kvp_file_info[pool].num_records, filep);

        fflush(filep);
        kvp_release_lock(pool);
}

static void kvp_update_mem_state(int pool)
{
        FILE *filep;
        size_t records_read = 0;
        struct kvp_record *record = kvp_file_info[pool].records;
        struct kvp_record *readp;
        int num_blocks = kvp_file_info[pool].num_blocks;
        int alloc_unit = sizeof(struct kvp_record) * ENTRIES_PER_BLOCK;

        kvp_acquire_lock(pool);

        filep = fopen(kvp_file_info[pool].fname, "r");
        if (!filep) {
                kvp_release_lock(pool);
                syslog(LOG_ERR, "Failed to open file, pool: %d", pool);
                exit(-1);
        }
        while (!feof(filep)) {
                readp = &record[records_read];
                records_read += fread(readp, sizeof(struct kvp_record),
                                        ENTRIES_PER_BLOCK * num_blocks,
                                        filep);

                if (!feof(filep)) {
                        /*
                         * We have more data to read.
                         */
                        num_blocks++;
                        record = realloc(record, alloc_unit * num_blocks);

                        if (record == NULL) {
                                syslog(LOG_ERR, "malloc failed");
                                exit(-1);
                        }
                        continue;
                }
                break;
        }

        kvp_file_info[pool].num_blocks = num_blocks;
        kvp_file_info[pool].records = record;
        kvp_file_info[pool].num_records = records_read;

        kvp_release_lock(pool);
}
static int kvp_file_init(void)
{
        int ret, fd;
        FILE *filep;
        size_t records_read;
        __u8 *fname;
        struct kvp_record *record;
        struct kvp_record *readp;
        int num_blocks;
        int i;
        int alloc_unit = sizeof(struct kvp_record) * ENTRIES_PER_BLOCK;

        if (access("/var/opt/hyperv", F_OK)) {
                if (mkdir("/var/opt/hyperv", S_IRUSR | S_IWUSR | S_IROTH)) {
                        syslog(LOG_ERR, " Failed to create /var/opt/hyperv");
                        exit(-1);
                }
        }

        for (i = 0; i < KVP_POOL_COUNT; i++) {
                fname = kvp_file_info[i].fname;
                records_read = 0;
                num_blocks = 1;
                sprintf(fname, "/var/opt/hyperv/.kvp_pool_%d", i);
                fd = open(fname, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IROTH);

                if (fd == -1)
                        return 1;


                filep = fopen(fname, "r");
                if (!filep)
                        return 1;

                record = malloc(alloc_unit * num_blocks);
                if (record == NULL) {
                        fclose(filep);
                        return 1;
                }
                while (!feof(filep)) {
                        readp = &record[records_read];
                        records_read += fread(readp, sizeof(struct kvp_record),
                                        ENTRIES_PER_BLOCK,
                                        filep);

                        if (!feof(filep)) {
                                /*
                                 * We have more data to read.
                                 */
                                num_blocks++;
                                record = realloc(record, alloc_unit *
                                                num_blocks);
                                if (record == NULL) {
                                        fclose(filep);
                                        return 1;
                                }
                                continue;
                        }
                        break;
                }
                kvp_file_info[i].fd = fd;
                kvp_file_info[i].num_blocks = num_blocks;
                kvp_file_info[i].records = record;
                kvp_file_info[i].num_records = records_read;
                fclose(filep);

        }

        return 0;
}

static int kvp_key_delete(int pool, __u8 *key, int key_size)
{
        int i;
        int j, k;
        int num_records;
        struct kvp_record *record;

        /*
         * First update the in-memory state.
         */
        kvp_update_mem_state(pool);

        num_records = kvp_file_info[pool].num_records;
        record = kvp_file_info[pool].records;

        for (i = 0; i < num_records; i++) {
                if (memcmp(key, record[i].key, key_size))
                        continue;
                /*
                 * Found a match; just move the remaining
                 * entries up.
                 */
                if (i == num_records) {
                        kvp_file_info[pool].num_records--;
                        kvp_update_file(pool);
                        return 0;
                }

                j = i;
                k = j + 1;
                for (; k < num_records; k++) {
                        strcpy(record[j].key, record[k].key);
                        strcpy(record[j].value, record[k].value);
                        j++;
                }

                kvp_file_info[pool].num_records--;
                kvp_update_file(pool);
                return 0;
        }
        return 1;
}

static int kvp_key_add_or_modify(int pool, __u8 *key, int key_size, __u8 *value,
                        int value_size)
{
        int i;
        int j, k;
        int num_records;
        struct kvp_record *record;
        int num_blocks;

        if ((key_size > HV_KVP_EXCHANGE_MAX_KEY_SIZE) ||
                (value_size > HV_KVP_EXCHANGE_MAX_VALUE_SIZE))
                return 1;

        /*
         * First update the in-memory state.
         */
        kvp_update_mem_state(pool);

        num_records = kvp_file_info[pool].num_records;
        record = kvp_file_info[pool].records;
        num_blocks = kvp_file_info[pool].num_blocks;

        for (i = 0; i < num_records; i++) {
                if (memcmp(key, record[i].key, key_size))
                        continue;
                /*
                 * Found a match; just update the value -
                 * this is the modify case.
                 */
                memcpy(record[i].value, value, value_size);
                kvp_update_file(pool);
                return 0;
        }

        /*
         * Need to add a new entry;
         */
        if (num_records == (ENTRIES_PER_BLOCK * num_blocks)) {
                /* Need to allocate a larger array for reg entries. */
                record = realloc(record, sizeof(struct kvp_record) *
                         ENTRIES_PER_BLOCK * (num_blocks + 1));

                if (record == NULL)
                        return 1;
                kvp_file_info[pool].num_blocks++;

        }
        memcpy(record[i].value, value, value_size);
        memcpy(record[i].key, key, key_size);
        kvp_file_info[pool].records = record;
        kvp_file_info[pool].num_records++;
        kvp_update_file(pool);
        return 0;
}

static int kvp_get_value(int pool, __u8 *key, int key_size, __u8 *value,
                        int value_size)
{
        int i;
        int num_records;
        struct kvp_record *record;

        if ((key_size > HV_KVP_EXCHANGE_MAX_KEY_SIZE) ||
                (value_size > HV_KVP_EXCHANGE_MAX_VALUE_SIZE))
                return 1;

        /*
         * First update the in-memory state.
         */
        kvp_update_mem_state(pool);

        num_records = kvp_file_info[pool].num_records;
        record = kvp_file_info[pool].records;

        for (i = 0; i < num_records; i++) {
                if (memcmp(key, record[i].key, key_size))
                        continue;
                /*
                 * Found a match; just copy the value out.
                 */
                memcpy(value, record[i].value, value_size);
                return 0;
        }

        return 1;
}

static void kvp_pool_enumerate(int pool, int index, __u8 *key, int key_size,
                                __u8 *value, int value_size)
{
        struct kvp_record *record;

        /*
         * First update our in-memory database.
         */
        kvp_update_mem_state(pool);
        record = kvp_file_info[pool].records;

        if (index >= kvp_file_info[pool].num_records) {
                /*
                 * This is an invalid index; terminate enumeration;
                 * - a NULL value will do the trick.
                 */
                strcpy(value, "");
                return;
        }

        memcpy(key, record[index].key, key_size);
        memcpy(value, record[index].value, value_size);
}


void kvp_get_os_info(void)
{
        FILE    *file;
        char    *p, buf[512];

        uname(&uts_buf);
        os_build = uts_buf.release;
        processor_arch = uts_buf.machine;

        /*
         * The current windows host (win7) expects the build
         * string to be of the form: x.y.z
         * Strip additional information we may have.
         */
        p = strchr(os_build, '-');
        if (p)
                *p = '\0';

        file = fopen("/etc/SuSE-release", "r");
        if (file != NULL)
                goto kvp_osinfo_found;
        file  = fopen("/etc/redhat-release", "r");
        if (file != NULL)
                goto kvp_osinfo_found;
        /*
         * Add code for other supported platforms.
         */

        /*
         * We don't have information about the os.
         */
        os_name = uts_buf.sysname;
        return;

kvp_osinfo_found:
        /* up to three lines */
        p = fgets(buf, sizeof(buf), file);
        if (p) {
                p = strchr(buf, '\n');
                if (p)
                        *p = '\0';
                p = strdup(buf);
                if (!p)
                        goto done;
                os_name = p;

                /* second line */
                p = fgets(buf, sizeof(buf), file);
                if (p) {
                        p = strchr(buf, '\n');
                        if (p)
                                *p = '\0';
                        p = strdup(buf);
                        if (!p)
                                goto done;
                        os_major = p;

                        /* third line */
                        p = fgets(buf, sizeof(buf), file);
                        if (p)  {
                                p = strchr(buf, '\n');
                                if (p)
                                        *p = '\0';
                                p = strdup(buf);
                                if (p)
                                        os_minor = p;
                        }
                }
        }

done:
        fclose(file);
        return;
}

static int
kvp_get_ip_address(int family, char *buffer, int length)
{
        struct ifaddrs *ifap;
        struct ifaddrs *curp;
        int ipv4_len = strlen("255.255.255.255") + 1;
        int ipv6_len = strlen("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")+1;
        int offset = 0;
        const char *str;
        char tmp[50];
        int error = 0;

        /*
         * On entry into this function, the buffer is capable of holding the
         * maximum key value (2048 bytes).
         */

        if (getifaddrs(&ifap)) {
                strcpy(buffer, "getifaddrs failed\n");
                return 1;
        }

        curp = ifap;
        while (curp != NULL) {
                if ((curp->ifa_addr != NULL) &&
                   (curp->ifa_addr->sa_family == family)) {
                        if (family == AF_INET) {
                                struct sockaddr_in *addr =
                                (struct sockaddr_in *) curp->ifa_addr;

                                str = inet_ntop(family, &addr->sin_addr,
                                                tmp, 50);
                                if (str == NULL) {
                                        strcpy(buffer, "inet_ntop failed\n");
                                        error = 1;
                                        goto getaddr_done;
                                }
                                if (offset == 0)
                                        strcpy(buffer, tmp);
                                else
                                        strcat(buffer, tmp);
                                strcat(buffer, ";");

                                offset += strlen(str) + 1;
                                if ((length - offset) < (ipv4_len + 1))
                                        goto getaddr_done;

                        } else {

                        /*
                         * We only support AF_INET and AF_INET6
                         * and the list of addresses is separated by a ";".
                         */
                                struct sockaddr_in6 *addr =
                                (struct sockaddr_in6 *) curp->ifa_addr;

                                str = inet_ntop(family,
                                        &addr->sin6_addr.s6_addr,
                                        tmp, 50);
                                if (str == NULL) {
                                        strcpy(buffer, "inet_ntop failed\n");
                                        error = 1;
                                        goto getaddr_done;
                                }
                                if (offset == 0)
                                        strcpy(buffer, tmp);
                                else
                                        strcat(buffer, tmp);
                                strcat(buffer, ";");
                                offset += strlen(str) + 1;
                                if ((length - offset) < (ipv6_len + 1))
                                        goto getaddr_done;

                        }

                }
                curp = curp->ifa_next;
        }

getaddr_done:
        freeifaddrs(ifap);
        return error;
}


static int
kvp_get_domain_name(char *buffer, int length)
{
        struct addrinfo hints, *info ;
        int error = 0;

        gethostname(buffer, length);
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = AF_INET; /*Get only ipv4 addrinfo. */
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_CANONNAME;

        error = getaddrinfo(buffer, NULL, &hints, &info);
        if (error != 0) {
                strcpy(buffer, "getaddrinfo failed\n");
                return error;
        }
        strcpy(buffer, info->ai_canonname);
        freeaddrinfo(info);
        return error;
}

static int
netlink_send(int fd, struct cn_msg *msg)
{
        struct nlmsghdr *nlh;
        unsigned int size;
        struct msghdr message;
        char buffer[64];
        struct iovec iov[2];

        size = NLMSG_SPACE(sizeof(struct cn_msg) + msg->len);

        nlh = (struct nlmsghdr *)buffer;
        nlh->nlmsg_seq = 0;
        nlh->nlmsg_pid = getpid();
        nlh->nlmsg_type = NLMSG_DONE;
        nlh->nlmsg_len = NLMSG_LENGTH(size - sizeof(*nlh));
        nlh->nlmsg_flags = 0;

        iov[0].iov_base = nlh;
        iov[0].iov_len = sizeof(*nlh);

        iov[1].iov_base = msg;
        iov[1].iov_len = size;

        memset(&message, 0, sizeof(message));
        message.msg_name = &addr;
        message.msg_namelen = sizeof(addr);
        message.msg_iov = iov;
        message.msg_iovlen = 2;

        return sendmsg(fd, &message, 0);
}

int main(void)
{
        int fd, len, sock_opt;
        int error;
        struct cn_msg *message;
        struct pollfd pfd;
        struct nlmsghdr *incoming_msg;
        struct cn_msg   *incoming_cn_msg;
        struct hv_kvp_msg *hv_msg;
        char    *p;
        char    *key_value;
        char    *key_name;

        daemon(1, 0);
        openlog("KVP", 0, LOG_USER);
        syslog(LOG_INFO, "KVP starting; pid is:%d", getpid());
        /*
         * Retrieve OS release information.
         */
        kvp_get_os_info();

        if (kvp_file_init()) {
                syslog(LOG_ERR, "Failed to initialize the pools");
                exit(-1);
        }

        fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
        if (fd < 0) {
                syslog(LOG_ERR, "netlink socket creation failed; error:%d", fd);
                exit(-1);
        }
        addr.nl_family = AF_NETLINK;
        addr.nl_pad = 0;
        addr.nl_pid = 0;
        addr.nl_groups = CN_KVP_IDX;


        error = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
        if (error < 0) {
                syslog(LOG_ERR, "bind failed; error:%d", error);
                close(fd);
                exit(-1);
        }
        sock_opt = addr.nl_groups;
        setsockopt(fd, 270, 1, &sock_opt, sizeof(sock_opt));
        /*
         * Register ourselves with the kernel.
         */
        message = (struct cn_msg *)kvp_send_buffer;
        message->id.idx = CN_KVP_IDX;
        message->id.val = CN_KVP_VAL;

        hv_msg = (struct hv_kvp_msg *)message->data;
        hv_msg->kvp_hdr.operation = KVP_OP_REGISTER;
        message->ack = 0;
        message->len = sizeof(struct hv_kvp_msg);

        len = netlink_send(fd, message);
        if (len < 0) {
                syslog(LOG_ERR, "netlink_send failed; error:%d", len);
                close(fd);
                exit(-1);
        }

        pfd.fd = fd;

        while (1) {
                struct sockaddr *addr_p = (struct sockaddr *) &addr;
                socklen_t addr_l = sizeof(addr);
                pfd.events = POLLIN;
                pfd.revents = 0;
                poll(&pfd, 1, -1);

                len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0,
                                addr_p, &addr_l);

                if (len < 0 || addr.nl_pid) {
                        syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
                                        addr.nl_pid, errno, strerror(errno));
                        close(fd);
                        return -1;
                }

                incoming_msg = (struct nlmsghdr *)kvp_recv_buffer;
                incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
                hv_msg = (struct hv_kvp_msg *)incoming_cn_msg->data;

                switch (hv_msg->kvp_hdr.operation) {
                case KVP_OP_REGISTER:
                        /*
                         * Driver is registering with us; stash away the version
                         * information.
                         */
                        p = (char *)hv_msg->body.kvp_register.version;
                        lic_version = malloc(strlen(p) + 1);
                        if (lic_version) {
                                strcpy(lic_version, p);
                                syslog(LOG_INFO, "KVP LIC Version: %s",
                                        lic_version);
                        } else {
                                syslog(LOG_ERR, "malloc failed");
                        }
                        continue;

                /*
                 * The current protocol with the kernel component uses a
                 * NULL key name to pass an error condition.
                 * For the SET, GET and DELETE operations,
                 * use the existing protocol to pass back error.
                 */

                case KVP_OP_SET:
                        if (kvp_key_add_or_modify(hv_msg->kvp_hdr.pool,
                                        hv_msg->body.kvp_set.data.key,
                                        hv_msg->body.kvp_set.data.key_size,
                                        hv_msg->body.kvp_set.data.value,
                                        hv_msg->body.kvp_set.data.value_size))
                                strcpy(hv_msg->body.kvp_set.data.key, "");
                        break;

                case KVP_OP_GET:
                        if (kvp_get_value(hv_msg->kvp_hdr.pool,
                                        hv_msg->body.kvp_set.data.key,
                                        hv_msg->body.kvp_set.data.key_size,
                                        hv_msg->body.kvp_set.data.value,
                                        hv_msg->body.kvp_set.data.value_size))
                                strcpy(hv_msg->body.kvp_set.data.key, "");
                        break;

                case KVP_OP_DELETE:
                        if (kvp_key_delete(hv_msg->kvp_hdr.pool,
                                        hv_msg->body.kvp_delete.key,
                                        hv_msg->body.kvp_delete.key_size))
                                strcpy(hv_msg->body.kvp_delete.key, "");
                        break;

                default:
                        break;
                }

                if (hv_msg->kvp_hdr.operation != KVP_OP_ENUMERATE)
                        goto kvp_done;

                /*
                 * If the pool is KVP_POOL_AUTO, dynamically generate
                 * both the key and the value; if not read from the
                 * appropriate pool.
                 */
                if (hv_msg->kvp_hdr.pool != KVP_POOL_AUTO) {
                        kvp_pool_enumerate(hv_msg->kvp_hdr.pool,
                                        hv_msg->body.kvp_enum_data.index,
                                        hv_msg->body.kvp_enum_data.data.key,
                                        HV_KVP_EXCHANGE_MAX_KEY_SIZE,
                                        hv_msg->body.kvp_enum_data.data.value,
                                        HV_KVP_EXCHANGE_MAX_VALUE_SIZE);
                        goto kvp_done;
                }

                hv_msg = (struct hv_kvp_msg *)incoming_cn_msg->data;
                key_name = (char *)hv_msg->body.kvp_enum_data.data.key;
                key_value = (char *)hv_msg->body.kvp_enum_data.data.value;

                switch (hv_msg->body.kvp_enum_data.index) {
                case FullyQualifiedDomainName:
                        kvp_get_domain_name(key_value,
                                        HV_KVP_EXCHANGE_MAX_VALUE_SIZE);
                        strcpy(key_name, "FullyQualifiedDomainName");
                        break;
                case IntegrationServicesVersion:
                        strcpy(key_name, "IntegrationServicesVersion");
                        strcpy(key_value, lic_version);
                        break;
                case NetworkAddressIPv4:
                        kvp_get_ip_address(AF_INET, key_value,
                                        HV_KVP_EXCHANGE_MAX_VALUE_SIZE);
                        strcpy(key_name, "NetworkAddressIPv4");
                        break;
                case NetworkAddressIPv6:
                        kvp_get_ip_address(AF_INET6, key_value,
                                        HV_KVP_EXCHANGE_MAX_VALUE_SIZE);
                        strcpy(key_name, "NetworkAddressIPv6");
                        break;
                case OSBuildNumber:
                        strcpy(key_value, os_build);
                        strcpy(key_name, "OSBuildNumber");
                        break;
                case OSName:
                        strcpy(key_value, os_name);
                        strcpy(key_name, "OSName");
                        break;
                case OSMajorVersion:
                        strcpy(key_value, os_major);
                        strcpy(key_name, "OSMajorVersion");
                        break;
                case OSMinorVersion:
                        strcpy(key_value, os_minor);
                        strcpy(key_name, "OSMinorVersion");
                        break;
                case OSVersion:
                        strcpy(key_value, os_build);
                        strcpy(key_name, "OSVersion");
                        break;
                case ProcessorArchitecture:
                        strcpy(key_value, processor_arch);
                        strcpy(key_name, "ProcessorArchitecture");
                        break;
                default:
                        strcpy(key_value, "Unknown Key");
                        /*
                         * We use a null key name to terminate enumeration.
                         */
                        strcpy(key_name, "");
                        break;
                }
                /*
                 * Send the value back to the kernel. The response is
                 * already in the receive buffer. Update the cn_msg header to
                 * reflect the key value that has been added to the message
                 */
kvp_done:

                incoming_cn_msg->id.idx = CN_KVP_IDX;
                incoming_cn_msg->id.val = CN_KVP_VAL;
                incoming_cn_msg->ack = 0;
                incoming_cn_msg->len = sizeof(struct hv_kvp_msg);

                len = netlink_send(fd, incoming_cn_msg);
                if (len < 0) {
                        syslog(LOG_ERR, "net_link send failed; error:%d", len);
                        exit(-1);
                }
        }

}