tools/hv/hv_kvp_daemon.c

/*
 * 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(EXIT_FAILURE);
	}
}

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(EXIT_FAILURE);
	}
}

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(EXIT_FAILURE);
	}

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

	if (ferror(filep) || fclose(filep)) {
		kvp_release_lock(pool);
		syslog(LOG_ERR, "Failed to write file, pool: %d", pool);
		exit(EXIT_FAILURE);
	}

	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(EXIT_FAILURE);
	}
	for (;;) {
		readp = &record[records_read];
		records_read += fread(readp, sizeof(struct kvp_record),
					ENTRIES_PER_BLOCK * num_blocks,
					filep);

		if (ferror(filep)) {
			syslog(LOG_ERR, "Failed to read file, pool: %d", pool);
			exit(EXIT_FAILURE);
		}

		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(EXIT_FAILURE);
			}
			continue;
		}
		break;
	}

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

	fclose(filep);
	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(EXIT_FAILURE);
		}
	}

	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;
		}
		for (;;) {
			readp = &record[records_read];
			records_read += fread(readp, sizeof(struct kvp_record),
					ENTRIES_PER_BLOCK,
					filep);

			if (ferror(filep)) {
				syslog(LOG_ERR, "Failed to read file, pool: %d",
				       i);
				exit(EXIT_FAILURE);
			}

			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(EXIT_FAILURE);
	}

	fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
	if (fd < 0) {
		syslog(LOG_ERR, "netlink socket creation failed; error:%d", fd);
		exit(EXIT_FAILURE);
	}
	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(EXIT_FAILURE);
	}
	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(EXIT_FAILURE);
	}

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

		if (addr.nl_pid) {
			syslog(LOG_WARNING, "Received packet from untrusted pid:%u",
					addr.nl_pid);
			continue;
		}

		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(EXIT_FAILURE);
		}
	}

}