gdhcp: Initial DHCP server implementation

2 files changed, 939 insertions, 1 deletions

diff --git a/gdhcp/gdhcp.h b/gdhcp/gdhcp.h
index 59b07ead..052ab90c 100644
--- a/gdhcp/gdhcp.h
+++ b/gdhcp/gdhcp.h
@@ -1,6 +1,6 @@
 /*
  *
- *  DHCP client library with GLib integration
+ *  DHCP library with GLib integration
  *
  *  Copyright (C) 2009-2010  Intel Corporation. All rights reserved.
  *
@@ -28,6 +28,7 @@
 extern "C" {
 #endif
 
+/* DHCP Client part*/
 struct _GDHCPClient;
 
 typedef struct _GDHCPClient GDHCPClient;
@@ -94,6 +95,44 @@ int g_dhcp_client_get_index(GDHCPClient *client);
 void g_dhcp_client_set_debug(GDHCPClient *client,
 				GDHCPDebugFunc func, gpointer user_data);
 
+/* DHCP Server */
+typedef enum {
+	G_DHCP_SERVER_ERROR_NONE,
+	G_DHCP_SERVER_ERROR_INTERFACE_UNAVAILABLE,
+	G_DHCP_SERVER_ERROR_INTERFACE_IN_USE,
+	G_DHCP_SERVER_ERROR_INTERFACE_DOWN,
+	G_DHCP_SERVER_ERROR_NOMEM,
+	G_DHCP_SERVER_ERROR_INVALID_INDEX,
+	G_DHCP_SERVER_ERROR_INVALID_OPTION,
+	G_DHCP_SERVER_ERROR_IP_ADDRESS_INVALID
+} GDHCPServerError;
+
+typedef void (*GDHCPSaveLeaseFunc) (unsigned char *mac,
+			unsigned int nip, unsigned int expire);
+struct _GDHCPServer;
+
+typedef struct _GDHCPServer GDHCPServer;
+
+GDHCPServer *g_dhcp_server_new(GDHCPType type,
+		int ifindex, GDHCPServerError *error);
+int g_dhcp_server_start(GDHCPServer *server);
+void g_dhcp_server_stop(GDHCPServer *server);
+
+GDHCPServer *g_dhcp_server_ref(GDHCPServer *server);
+void g_dhcp_server_unref(GDHCPServer *server);
+
+int g_dhcp_server_set_option(GDHCPServer *server,
+		unsigned char option_code, const char *option_value);
+int g_dhcp_server_set_ip_range(GDHCPServer *server,
+		const char *start_ip, const char *end_ip);
+void g_dhcp_server_load_lease(GDHCPServer *dhcp_server, unsigned int expire,
+				unsigned char *mac, unsigned int lease_ip);
+void g_dhcp_server_set_debug(GDHCPServer *server,
+				GDHCPDebugFunc func, gpointer user_data);
+void g_dhcp_server_set_lease_time(GDHCPServer *dhcp_server,
+						unsigned int lease_time);
+void g_dhcp_server_set_save_lease(GDHCPServer *dhcp_server,
+				GDHCPSaveLeaseFunc func, gpointer user_data);
 #ifdef __cplusplus
 }
 #endif
diff --git a/gdhcp/server.c b/gdhcp/server.c
new file mode 100644
index 00000000..7322e6e2
--- /dev/null
+++ b/gdhcp/server.c
@@ -0,0 +1,899 @@
+/*
+ *
+ *  DHCP Server library with GLib integration
+ *
+ *  Copyright (C) 2009-2010  Intel Corporation. All rights reserved.
+ *
+ *  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.  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
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <arpa/inet.h>
+
+#include <netpacket/packet.h>
+#include <net/ethernet.h>
+#include <net/if_arp.h>
+
+#include <linux/if.h>
+#include <linux/filter.h>
+
+#include <glib.h>
+
+#include "common.h"
+
+/* 8 hours */
+#define DEFAULT_DHCP_LEASE_SEC (8*60*60)
+
+/* 5 minutes  */
+#define OFFER_TIME (5*60)
+
+struct _GDHCPServer {
+	gint ref_count;
+	GDHCPType type;
+	gboolean started;
+	int ifindex;
+	char *interface;
+	uint32_t start_ip;
+	uint32_t end_ip;
+	uint32_t server_nip;
+	uint32_t lease_seconds;
+	int listener_sockfd;
+	guint listener_watch;
+	GIOChannel *listener_channel;
+	GList *lease_list;
+	GHashTable *nip_lease_hash;
+	GHashTable *option_hash; /* Options send to client */
+	GDHCPSaveLeaseFunc save_lease_func;
+	GDHCPDebugFunc debug_func;
+	gpointer debug_data;
+};
+
+struct dhcp_lease {
+	time_t expire;
+	uint32_t lease_nip;
+	uint8_t lease_mac[ETH_ALEN];
+};
+
+static inline void debug(GDHCPServer *server, const char *format, ...)
+{
+	char str[256];
+	va_list ap;
+
+	if (server->debug_func == NULL)
+		return;
+
+	va_start(ap, format);
+
+	if (vsnprintf(str, sizeof(str), format, ap) > 0)
+		server->debug_func(str, server->debug_data);
+
+	va_end(ap);
+}
+
+static struct dhcp_lease *find_lease_by_mac(GDHCPServer *dhcp_server,
+						const uint8_t *mac)
+{
+	GList *list;
+
+	for (list = dhcp_server->lease_list; list; list = list->next) {
+		struct dhcp_lease *lease = list->data;
+
+		if (memcmp(lease->lease_mac, mac, ETH_ALEN) == 0)
+			return lease;
+	}
+
+	return NULL;
+}
+
+static void remove_lease(GDHCPServer *dhcp_server, struct dhcp_lease *lease)
+{
+	dhcp_server->lease_list =
+			g_list_remove(dhcp_server->lease_list, lease);
+
+	g_hash_table_remove(dhcp_server->nip_lease_hash,
+				GINT_TO_POINTER((int) lease->lease_nip));
+	g_free(lease);
+}
+
+/* Clear the old lease and create the new one */
+static int get_lease(GDHCPServer *dhcp_server, uint32_t yiaddr,
+				const uint8_t *mac, struct dhcp_lease **lease)
+{
+	struct dhcp_lease *lease_nip, *lease_mac;
+
+	if (yiaddr == 0)
+		return -ENXIO;
+
+	if (ntohl(yiaddr) < dhcp_server->start_ip)
+		return -ENXIO;
+
+	if (ntohl(yiaddr) > dhcp_server->end_ip)
+		return -ENXIO;
+
+	if (memcmp(mac, MAC_BCAST_ADDR, ETH_ALEN) == 0)
+		return -ENXIO;
+
+	if (memcmp(mac, MAC_ANY_ADDR, ETH_ALEN) == 0)
+		return -ENXIO;
+
+	lease_mac = find_lease_by_mac(dhcp_server, mac);
+
+	lease_nip = g_hash_table_lookup(dhcp_server->nip_lease_hash,
+						GINT_TO_POINTER((int) yiaddr));
+	debug(dhcp_server, "lease_mac %p lease_nip %p", lease_mac, lease_nip);
+
+	if (lease_nip != NULL) {
+		dhcp_server->lease_list =
+				g_list_remove(dhcp_server->lease_list,
+								lease_nip);
+		g_hash_table_remove(dhcp_server->nip_lease_hash,
+					GINT_TO_POINTER((int) yiaddr));
+
+		if (lease_mac == NULL)
+			*lease = lease_nip;
+		else if (lease_nip != lease_mac) {
+			remove_lease(dhcp_server, lease_mac);
+			*lease = lease_nip;
+		} else
+			*lease = lease_nip;
+
+		return 0;
+	}
+
+	if (lease_mac != NULL) {
+		dhcp_server->lease_list =
+				g_list_remove(dhcp_server->lease_list,
+								lease_mac);
+		g_hash_table_remove(dhcp_server->nip_lease_hash,
+				GINT_TO_POINTER((int) lease_mac->lease_nip));
+		*lease = lease_mac;
+
+		return 0;
+	}
+
+	*lease = g_try_new0(struct dhcp_lease, 1);
+	if (*lease == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static gint compare_expire(gconstpointer a, gconstpointer b)
+{
+	const struct dhcp_lease *lease1 = a;
+	const struct dhcp_lease *lease2 = b;
+
+	return lease2->expire - lease1->expire;
+}
+
+static struct dhcp_lease *add_lease(GDHCPServer *dhcp_server, uint32_t expire,
+					const uint8_t *chaddr, uint32_t yiaddr)
+{
+	struct dhcp_lease *lease = NULL;
+	int ret;
+
+	ret = get_lease(dhcp_server, yiaddr, chaddr, &lease);
+	if (ret != 0)
+		return NULL;
+
+	memset(lease, 0, sizeof(*lease));
+
+	memcpy(lease->lease_mac, chaddr, ETH_ALEN);
+	lease->lease_nip = yiaddr;
+
+	if (expire == 0)
+		lease->expire = time(NULL) + dhcp_server->lease_seconds;
+	else
+		lease->expire = expire;
+
+	dhcp_server->lease_list = g_list_insert_sorted(dhcp_server->lease_list,
+							lease, compare_expire);
+
+	g_hash_table_insert(dhcp_server->nip_lease_hash,
+				GINT_TO_POINTER((int) lease->lease_nip), lease);
+
+	return lease;
+}
+
+static struct dhcp_lease *find_lease_by_nip(GDHCPServer *dhcp_server,
+								uint32_t nip)
+{
+	return g_hash_table_lookup(dhcp_server->nip_lease_hash,
+						GINT_TO_POINTER((int) nip));
+}
+
+/* Check if the IP is taken; if it is, add it to the lease table */
+static gboolean arp_check(uint32_t nip, const uint8_t *safe_mac)
+{
+	/* TODO: Add ARP checking */
+	return TRUE;
+}
+
+static gboolean is_expired_lease(struct dhcp_lease *lease)
+{
+	if (lease->expire < time(NULL))
+		return TRUE;
+
+	return FALSE;
+}
+
+static uint32_t find_free_or_expired_nip(GDHCPServer *dhcp_server,
+					const uint8_t *safe_mac)
+{
+	uint32_t ip_addr;
+	struct dhcp_lease *lease;
+	GList *list;
+	ip_addr = dhcp_server->start_ip;
+	for (; ip_addr <= dhcp_server->end_ip; ip_addr++) {
+		/* e.g. 192.168.55.0 */
+		if ((ip_addr & 0xff) == 0)
+			continue;
+
+		/* e.g. 192.168.55.255 */
+		if ((ip_addr & 0xff) == 0xff)
+			continue;
+
+		lease = find_lease_by_nip(dhcp_server,
+				(uint32_t) htonl(ip_addr));
+		if (lease != NULL)
+			continue;
+
+		if (arp_check(htonl(ip_addr), safe_mac) == TRUE)
+			return htonl(ip_addr);
+	}
+
+	/* The last lease is the oldest one */
+	list = g_list_last(dhcp_server->lease_list);
+	if (list == NULL)
+		return 0;
+
+	lease = list->data;
+	if (lease == NULL)
+		return 0;
+
+	 if (is_expired_lease(lease) == FALSE)
+		return 0;
+
+	 if (arp_check(lease->lease_nip, safe_mac) == FALSE)
+		return 0;
+
+	return lease->lease_nip;
+}
+
+static void lease_set_expire(GDHCPServer *dhcp_server,
+			struct dhcp_lease *lease, uint32_t expire)
+{
+	dhcp_server->lease_list = g_list_remove(dhcp_server->lease_list, lease);
+
+	lease->expire = expire;
+
+	dhcp_server->lease_list = g_list_insert_sorted(dhcp_server->lease_list,
+							lease, compare_expire);
+}
+
+static void distroy_lease_table(GDHCPServer *dhcp_server)
+{
+	GList *list;
+
+	g_hash_table_destroy(dhcp_server->nip_lease_hash);
+
+	dhcp_server->nip_lease_hash = NULL;
+
+	for (list = dhcp_server->lease_list; list; list = list->next) {
+		struct dhcp_lease *lease = list->data;
+
+		g_free(lease);
+	}
+
+	g_list_free(dhcp_server->lease_list);
+
+	dhcp_server->lease_list = NULL;
+}
+static uint32_t get_interface_address(int index)
+{
+	struct ifreq ifr;
+	int sk, err;
+	struct sockaddr_in *server_ip;
+	uint32_t ret = 0;
+
+	sk = socket(PF_INET, SOCK_DGRAM, 0);
+	if (sk < 0) {
+		perror("Open socket error");
+		return 0;
+	}
+
+	memset(&ifr, 0, sizeof(ifr));
+	ifr.ifr_ifindex = index;
+
+	err = ioctl(sk, SIOCGIFNAME, &ifr);
+	if (err < 0) {
+		perror("Get interface name error");
+		goto done;
+	}
+
+	err = ioctl(sk, SIOCGIFADDR, &ifr);
+	if (err < 0) {
+		perror("Get ip address error");
+		goto done;
+	}
+
+	server_ip = (struct sockaddr_in *) &ifr.ifr_addr;
+	ret = server_ip->sin_addr.s_addr;
+
+done:
+	close(sk);
+
+	return ret;
+}
+
+GDHCPServer *g_dhcp_server_new(GDHCPType type,
+		int ifindex, GDHCPServerError *error)
+{
+	GDHCPServer *dhcp_server = NULL;
+
+	if (ifindex < 0) {
+		*error = G_DHCP_SERVER_ERROR_INVALID_INDEX;
+		return NULL;
+	}
+
+	dhcp_server = g_try_new0(GDHCPServer, 1);
+	if (dhcp_server == NULL) {
+		*error = G_DHCP_SERVER_ERROR_NOMEM;
+		return NULL;
+	}
+
+	dhcp_server->interface = get_interface_name(ifindex);
+	if (dhcp_server->interface == NULL) {
+		*error = G_DHCP_SERVER_ERROR_INTERFACE_UNAVAILABLE;
+		goto error;
+	}
+
+	if (interface_is_up(ifindex) == FALSE) {
+		*error = G_DHCP_SERVER_ERROR_INTERFACE_DOWN;
+		goto error;
+	}
+
+	dhcp_server->server_nip = get_interface_address(ifindex);
+	if (dhcp_server->server_nip == 0) {
+		*error = G_DHCP_SERVER_ERROR_IP_ADDRESS_INVALID;
+		goto error;
+	}
+
+	dhcp_server->nip_lease_hash = g_hash_table_new_full(g_direct_hash,
+						g_direct_equal, NULL, NULL);
+	dhcp_server->option_hash = g_hash_table_new_full(g_direct_hash,
+						g_direct_equal, NULL, NULL);
+
+	dhcp_server->started = FALSE;
+
+	/* All the leases have the same fixed lease time,
+	 * do not support DHCP_LEASE_TIME option from client.
+	 */
+	dhcp_server->lease_seconds = DEFAULT_DHCP_LEASE_SEC;
+
+	dhcp_server->type = type;
+	dhcp_server->ref_count = 1;
+	dhcp_server->ifindex = ifindex;
+	dhcp_server->listener_sockfd = -1;
+	dhcp_server->listener_watch = -1;
+	dhcp_server->listener_channel = NULL;
+	dhcp_server->save_lease_func = NULL;
+	dhcp_server->debug_func = NULL;
+	dhcp_server->debug_data = NULL;
+
+	*error = G_DHCP_SERVER_ERROR_NONE;
+
+	return dhcp_server;
+
+error:
+	g_free(dhcp_server->interface);
+	g_free(dhcp_server);
+	return NULL;
+}
+
+
+static uint8_t check_packet_type(struct dhcp_packet *packet)
+{
+	uint8_t *type;
+
+	if (packet->hlen != ETH_ALEN)
+		return 0;
+
+	if (packet->op != BOOTREQUEST)
+		return 0;
+
+	type = dhcp_get_option(packet, DHCP_MESSAGE_TYPE);
+
+	if (type == NULL)
+		return 0;
+
+	if (*type < DHCP_MINTYPE)
+		return 0;
+
+	if (*type > DHCP_MAXTYPE)
+		return 0;
+
+	return *type;
+}
+
+static void init_packet(GDHCPServer *dhcp_server, struct dhcp_packet *packet,
+				struct dhcp_packet *client_packet, char type)
+{
+	/* Sets op, htype, hlen, cookie fields
+	 * and adds DHCP_MESSAGE_TYPE option */
+	dhcp_init_header(packet, type);
+
+	packet->xid = client_packet->xid;
+	memcpy(packet->chaddr, client_packet->chaddr,
+				sizeof(client_packet->chaddr));
+	packet->flags = client_packet->flags;
+	packet->gateway_nip = client_packet->gateway_nip;
+	packet->ciaddr = client_packet->ciaddr;
+	dhcp_add_simple_option(packet, DHCP_SERVER_ID, dhcp_server->server_nip);
+}
+
+static void add_option(gpointer key, gpointer value, gpointer user_data)
+{
+	const char *option_value = value;
+	uint8_t option_code = GPOINTER_TO_INT(key);
+	struct in_addr nip;
+	struct dhcp_packet *packet = user_data;
+
+	if (option_value == NULL)
+		return;
+
+	switch (option_code) {
+	case G_DHCP_SUBNET:
+	case G_DHCP_ROUTER:
+	case G_DHCP_DNS_SERVER:
+		if (inet_aton(option_value, &nip) == 0)
+			return;
+
+		dhcp_add_simple_option(packet, (uint8_t) option_code,
+								nip.s_addr);
+		break;
+	default:
+		return;
+	}
+}
+
+static void add_server_options(GDHCPServer *dhcp_server,
+				struct dhcp_packet *packet)
+{
+	g_hash_table_foreach(dhcp_server->option_hash,
+				add_option, packet);
+}
+
+static gboolean check_requested_nip(GDHCPServer *dhcp_server,
+					uint32_t requested_nip)
+{
+	struct dhcp_lease *lease;
+
+	if (requested_nip == 0)
+		return FALSE;
+
+	if (ntohl(requested_nip) < dhcp_server->start_ip)
+		return FALSE;
+
+	if (ntohl(requested_nip) > dhcp_server->end_ip)
+		return FALSE;
+
+	lease = find_lease_by_nip(dhcp_server, requested_nip);
+	if (lease == NULL)
+		return TRUE;
+
+	if (is_expired_lease(lease) == FALSE)
+		return FALSE;
+
+	return TRUE;
+}
+
+static void send_packet_to_client(GDHCPServer *dhcp_server,
+				struct dhcp_packet *dhcp_pkt)
+{
+	const uint8_t *chaddr;
+	uint32_t ciaddr;
+
+	if ((dhcp_pkt->flags & htons(BROADCAST_FLAG))
+				|| dhcp_pkt->ciaddr == 0) {
+		debug(dhcp_server, "Broadcasting packet to client");
+		ciaddr = INADDR_BROADCAST;
+		chaddr = MAC_BCAST_ADDR;
+	} else {
+		debug(dhcp_server, "Unicasting packet to client ciaddr");
+		ciaddr = dhcp_pkt->ciaddr;
+		chaddr = dhcp_pkt->chaddr;
+	}
+
+	dhcp_send_raw_packet(dhcp_pkt,
+		dhcp_server->server_nip, SERVER_PORT,
+		ciaddr, CLIENT_PORT, chaddr,
+		dhcp_server->ifindex);
+}
+
+static void send_offer(GDHCPServer *dhcp_server,
+			struct dhcp_packet *client_packet,
+				struct dhcp_lease *lease,
+					uint32_t requested_nip)
+{
+	struct dhcp_packet packet;
+	struct in_addr addr;
+
+	init_packet(dhcp_server, &packet, client_packet, DHCPOFFER);
+
+	if (lease)
+		packet.yiaddr = lease->lease_nip;
+	else if (check_requested_nip(dhcp_server, requested_nip) == TRUE)
+		packet.yiaddr = requested_nip;
+	else
+		packet.yiaddr = find_free_or_expired_nip(
+				dhcp_server, client_packet->chaddr);
+
+	debug(dhcp_server, "find yiaddr %u", packet.yiaddr);
+
+	if (!packet.yiaddr) {
+		debug(dhcp_server, "Err: Can not found lease and send offer");
+		return;
+	}
+
+	lease = add_lease(dhcp_server, OFFER_TIME,
+				packet.chaddr, packet.yiaddr);
+	if (lease == NULL) {
+		debug(dhcp_server,
+				"Err: No free IP addresses. OFFER abandoned");
+		return;
+	}
+
+	dhcp_add_simple_option(&packet, DHCP_LEASE_TIME,
+				htonl(dhcp_server->lease_seconds));
+	add_server_options(dhcp_server, &packet);
+
+	addr.s_addr = packet.yiaddr;
+
+	debug(dhcp_server, "Sending OFFER of %s", inet_ntoa(addr));
+	send_packet_to_client(dhcp_server, &packet);
+}
+
+static void save_lease(GDHCPServer *dhcp_server)
+{
+	GList *list;
+
+	if (dhcp_server->save_lease_func == NULL)
+		return;
+
+	for (list = dhcp_server->lease_list; list; list = list->next) {
+		struct dhcp_lease *lease = list->data;
+		dhcp_server->save_lease_func(lease->lease_mac,
+					lease->lease_nip, lease->expire);
+	}
+}
+
+static void send_ACK(GDHCPServer *dhcp_server,
+		struct dhcp_packet *client_packet, uint32_t yiaddr)
+{
+	struct dhcp_packet packet;
+	uint32_t lease_time_sec;
+	struct in_addr addr;
+
+	init_packet(dhcp_server, &packet, client_packet, DHCPACK);
+	packet.yiaddr = yiaddr;
+
+	lease_time_sec = dhcp_server->lease_seconds;
+
+	dhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
+
+	add_server_options(dhcp_server, &packet);
+
+	addr.s_addr = yiaddr;
+
+	debug(dhcp_server, "Sending ACK to %s", inet_ntoa(addr));
+
+	send_packet_to_client(dhcp_server, &packet);
+
+	add_lease(dhcp_server, 0, packet.chaddr, packet.yiaddr);
+}
+
+static void send_NAK(GDHCPServer *dhcp_server,
+			struct dhcp_packet *client_packet)
+{
+	struct dhcp_packet packet;
+
+	init_packet(dhcp_server, &packet, client_packet, DHCPNAK);
+
+	debug(dhcp_server, "Sending NAK");
+
+	dhcp_send_raw_packet(&packet,
+			dhcp_server->server_nip, SERVER_PORT,
+			INADDR_BROADCAST, CLIENT_PORT, MAC_BCAST_ADDR,
+			dhcp_server->ifindex);
+}
+
+static void send_inform(GDHCPServer *dhcp_server,
+				struct dhcp_packet *client_packet)
+{
+	struct dhcp_packet packet;
+
+	init_packet(dhcp_server, &packet, client_packet, DHCPACK);
+	add_server_options(dhcp_server, &packet);
+	send_packet_to_client(dhcp_server, &packet);
+}
+
+static gboolean listener_event(GIOChannel *channel, GIOCondition condition,
+							gpointer user_data)
+{
+	GDHCPServer *dhcp_server = user_data;
+	struct dhcp_packet packet;
+	struct dhcp_lease *lease;
+	uint32_t requested_nip = 0;
+	uint8_t type, *server_id_option, *request_ip_option;
+	int re;
+
+	if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
+		dhcp_server->listener_watch = 0;
+		return FALSE;
+	}
+
+	re = dhcp_recv_l3_packet(&packet, dhcp_server->listener_sockfd);
+	if (re < 0)
+		return TRUE;
+
+	type = check_packet_type(&packet);
+	if (type == 0)
+		return TRUE;
+
+	server_id_option = dhcp_get_option(&packet, DHCP_SERVER_ID);
+	if (server_id_option) {
+		uint32_t server_nid = dhcp_get_unaligned(
+					(uint32_t *) server_id_option);
+
+		if (server_nid != dhcp_server->server_nip)
+			return TRUE;
+	}
+
+	request_ip_option = dhcp_get_option(&packet, DHCP_REQUESTED_IP);
+	if (request_ip_option)
+		requested_nip = dhcp_get_unaligned(
+					(uint32_t *) request_ip_option);
+
+	lease = find_lease_by_mac(dhcp_server, packet.chaddr);
+
+	switch (type) {
+		case DHCPDISCOVER:
+			debug(dhcp_server, "Received DISCOVER");
+
+			send_offer(dhcp_server, &packet, lease, requested_nip);
+		break;
+		case DHCPREQUEST:
+			debug(dhcp_server, "Received REQUEST");
+			if (requested_nip == 0) {
+				requested_nip = packet.ciaddr;
+				if (requested_nip == 0)
+					break;
+			}
+
+			if (lease && requested_nip == lease->lease_nip) {
+				send_ACK(dhcp_server, &packet,
+						lease->lease_nip);
+				break;
+			}
+
+			if (server_id_option)
+				send_NAK(dhcp_server, &packet);
+
+		break;
+		case DHCPDECLINE:
+			debug(dhcp_server, "Received DECLINE");
+
+			if (server_id_option == NULL)
+				break;
+
+			if (request_ip_option == NULL)
+				break;
+
+			if (lease == NULL)
+				break;
+
+			if (requested_nip == lease->lease_nip)
+				remove_lease(dhcp_server, lease);
+
+		break;
+		case DHCPRELEASE:
+			debug(dhcp_server, "Received RELEASE");
+
+			if (server_id_option == NULL)
+				break;
+
+			if (lease == NULL)
+				break;
+
+			if (packet.ciaddr == lease->lease_nip)
+				lease_set_expire(dhcp_server, lease,
+								time(NULL));
+		break;
+		case DHCPINFORM:
+			debug(dhcp_server, "Received INFORM");
+			send_inform(dhcp_server, &packet);
+		break;
+	}
+
+	return TRUE;
+}
+
+/* Caller need to load leases before call it */
+int g_dhcp_server_start(GDHCPServer *dhcp_server)
+{
+	GIOChannel *listener_channel;
+	int listener_sockfd;
+
+	if (dhcp_server->started == TRUE)
+		return 0;
+
+	listener_sockfd = dhcp_l3_socket(SERVER_PORT,
+				dhcp_server->interface);
+	if (listener_sockfd < 0)
+		return -EIO;
+
+	listener_channel = g_io_channel_unix_new(listener_sockfd);
+	if (listener_channel == NULL) {
+		close(listener_sockfd);
+		return -EIO;
+	}
+
+	dhcp_server->listener_sockfd = listener_sockfd;
+	dhcp_server->listener_channel = listener_channel;
+
+	g_io_channel_set_close_on_unref(listener_channel, TRUE);
+	dhcp_server->listener_watch =
+			g_io_add_watch_full(listener_channel,
+						G_PRIORITY_HIGH, G_IO_IN,
+						listener_event, dhcp_server,
+								NULL);
+	g_io_channel_unref(dhcp_server->listener_channel);
+
+	dhcp_server->started = TRUE;
+
+	return 0;
+}
+
+int g_dhcp_server_set_option(GDHCPServer *dhcp_server,
+		unsigned char option_code, const char *option_value)
+{
+	struct in_addr nip;
+
+	if (option_value == NULL)
+		return -EINVAL;
+
+	debug(dhcp_server, "option_code %d option_value %s",
+					option_code, option_value);
+	switch (option_code) {
+	case G_DHCP_SUBNET:
+	case G_DHCP_ROUTER:
+	case G_DHCP_DNS_SERVER:
+		if (inet_aton(option_value, &nip) == 0)
+			return -ENXIO;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	g_hash_table_replace(dhcp_server->option_hash,
+			GINT_TO_POINTER((int) option_code),
+					(gpointer) option_value);
+	return 0;
+}
+
+void g_dhcp_server_set_save_lease(GDHCPServer *dhcp_server,
+				GDHCPSaveLeaseFunc func, gpointer user_data)
+{
+	if (dhcp_server == NULL)
+		return;
+
+	dhcp_server->save_lease_func = func;
+}
+
+GDHCPServer *g_dhcp_server_ref(GDHCPServer *dhcp_server)
+{
+	if (dhcp_server == NULL)
+		return NULL;
+
+	g_atomic_int_inc(&dhcp_server->ref_count);
+
+	return dhcp_server;
+}
+
+void g_dhcp_server_stop(GDHCPServer *dhcp_server)
+{
+	/* Save leases, before stop; load them before start */
+	save_lease(dhcp_server);
+
+	if (dhcp_server->listener_watch > 0) {
+		g_source_remove(dhcp_server->listener_watch);
+		dhcp_server->listener_watch = 0;
+	}
+
+	dhcp_server->listener_channel = NULL;
+
+	dhcp_server->started = FALSE;
+}
+
+void g_dhcp_server_unref(GDHCPServer *dhcp_server)
+{
+	if (dhcp_server == NULL)
+		return;
+
+	if (g_atomic_int_dec_and_test(&dhcp_server->ref_count) == FALSE)
+		return;
+
+	g_dhcp_server_stop(dhcp_server);
+
+	g_hash_table_destroy(dhcp_server->option_hash);
+
+	distroy_lease_table(dhcp_server);
+
+	g_free(dhcp_server->interface);
+
+	g_free(dhcp_server);
+}
+
+void g_dhcp_server_load_lease(GDHCPServer *dhcp_server, unsigned int expire,
+				unsigned char *mac, unsigned int lease_ip)
+{
+	add_lease(dhcp_server, expire, mac, lease_ip);
+}
+
+int g_dhcp_server_set_ip_range(GDHCPServer *dhcp_server,
+		const char *start_ip, const char *end_ip)
+{
+	struct in_addr _host_addr;
+
+	if (inet_aton(start_ip, &_host_addr) == 0)
+		return -ENXIO;
+
+	dhcp_server->start_ip = ntohl(_host_addr.s_addr);
+
+	if (inet_aton(end_ip, &_host_addr) == 0)
+		return -ENXIO;
+
+	dhcp_server->end_ip = ntohl(_host_addr.s_addr);
+
+	return 0;
+}
+
+void g_dhcp_server_set_lease_time(GDHCPServer *dhcp_server, unsigned int lease_time)
+{
+	if (dhcp_server == NULL)
+		return;
+
+	dhcp_server->lease_seconds = lease_time;
+}
+
+void g_dhcp_server_set_debug(GDHCPServer *dhcp_server,
+				GDHCPDebugFunc func, gpointer user_data)
+{
+	if (dhcp_server == NULL)
+		return;
+
+	dhcp_server->debug_func = func;
+	dhcp_server->debug_data = user_data;
+}