/* serverpacket.c * * Construct and send DHCP server packets * * Russ Dill <Russ.Dill@asu.edu> July 2001 * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * 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., 675 Mass Ave, Cambridge, MA 02139, USA. */#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <string.h>#include <time.h>#include "common.h"#include "serverpacket.h"#include "dhcpd.h"#include "options.h"#include "static_leases.h"/* send a packet to giaddr using the kernel ip stack */static int send_packet_to_relay(struct dhcpMessage *payload){	DEBUG(LOG_INFO, "Forwarding packet to relay");	return udhcp_kernel_packet(payload, server_config.server, SERVER_PORT,			payload->giaddr, SERVER_PORT);}/* send a packet to a specific arp address and ip address by creating our own ip packet */static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast){	uint8_t *chaddr;	uint32_t ciaddr;	if (force_broadcast) {		DEBUG(LOG_INFO, "broadcasting packet to client (NAK)");		ciaddr = INADDR_BROADCAST;		chaddr = MAC_BCAST_ADDR;	} else if (payload->ciaddr) {		DEBUG(LOG_INFO, "unicasting packet to client ciaddr");		ciaddr = payload->ciaddr;		chaddr = payload->chaddr;	} else if (ntohs(payload->flags) & BROADCAST_FLAG) {		DEBUG(LOG_INFO, "broadcasting packet to client (requested)");		ciaddr = INADDR_BROADCAST;		chaddr = MAC_BCAST_ADDR;	} else {		DEBUG(LOG_INFO, "unicasting packet to client yiaddr");		ciaddr = payload->yiaddr;		chaddr = payload->chaddr;	}	return udhcp_raw_packet(payload, server_config.server, SERVER_PORT,			ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);}/* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */static int send_packet(struct dhcpMessage *payload, int force_broadcast){	int ret;	if (payload->giaddr)		ret = send_packet_to_relay(payload);	else ret = send_packet_to_client(payload, force_broadcast);	return ret;}static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type){	udhcp_init_header(packet, type);	packet->xid = oldpacket->xid;	memcpy(packet->chaddr, oldpacket->chaddr, 16);	packet->flags = oldpacket->flags;	packet->giaddr = oldpacket->giaddr;	packet->ciaddr = oldpacket->ciaddr;	add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);}/* add in the bootp options */static void add_bootp_options(struct dhcpMessage *packet){	packet->siaddr = server_config.siaddr;	if (server_config.sname)		strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);	if (server_config.boot_file)		strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);}/* send a DHCP OFFER to a DHCP DISCOVER */int sendOffer(struct dhcpMessage *oldpacket){	struct dhcpMessage packet;	struct dhcpOfferedAddr *lease = NULL;	uint32_t req_align, lease_time_align = server_config.lease;	uint8_t *req, *lease_time;	struct option_set *curr;	struct in_addr addr;	uint32_t static_lease_ip;	init_packet(&packet, oldpacket, DHCPOFFER);	static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);	/* ADDME: if static, short circuit */	if(!static_lease_ip)	{	/* the client is in our lease/offered table */	if ((lease = find_lease_by_chaddr(oldpacket->chaddr))) {		if (!lease_expired(lease))			lease_time_align = lease->expires - time(0);		packet.yiaddr = lease->yiaddr;	/* Or the client has a requested ip */	} else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP)) &&		   /* Don't look here (ugly hackish thing to do) */		   memcpy(&req_align, req, 4) &&		   /* and the ip is in the lease range */		   ntohl(req_align) >= ntohl(server_config.start) &&		   ntohl(req_align) <= ntohl(server_config.end) &&			!static_lease_ip &&  /* Check that its not a static lease */			/* and is not already taken/offered */		   ((!(lease = find_lease_by_yiaddr(req_align)) ||		   /* or its taken, but expired */ /* ADDME: or maybe in here */		   lease_expired(lease)))) {				packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */			/* otherwise, find a free IP */	} else {			/* Is it a static lease? (No, because find_address skips static lease) */		packet.yiaddr = find_address(0);		/* try for an expired lease */		if (!packet.yiaddr) packet.yiaddr = find_address(1);	}	if(!packet.yiaddr) {		LOG(LOG_WARNING, "no IP addresses to give -- OFFER abandoned");		return -1;	}	if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {		LOG(LOG_WARNING, "lease pool is full -- OFFER abandoned");		return -1;	}	if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {		memcpy(&lease_time_align, lease_time, 4);		lease_time_align = ntohl(lease_time_align);		if (lease_time_align > server_config.lease)			lease_time_align = server_config.lease;	}	/* Make sure we aren't just using the lease time from the previous offer */	if (lease_time_align < server_config.min_lease)		lease_time_align = server_config.lease;	}	/* ADDME: end of short circuit */	else	{		/* It is a static lease... use it */		packet.yiaddr = static_lease_ip;	}	add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));	curr = server_config.options;	while (curr) {		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)			add_option_string(packet.options, curr->data);		curr = curr->next;	}	add_bootp_options(&packet);	addr.s_addr = packet.yiaddr;	LOG(LOG_INFO, "sending OFFER of %s", inet_ntoa(addr));	return send_packet(&packet, 0);}int sendNAK(struct dhcpMessage *oldpacket){	struct dhcpMessage packet;	init_packet(&packet, oldpacket, DHCPNAK);	DEBUG(LOG_INFO, "sending NAK");	return send_packet(&packet, 1);}int sendACK(struct dhcpMessage *oldpacket, uint32_t yiaddr){	struct dhcpMessage packet;	struct option_set *curr;	uint8_t *lease_time;	uint32_t lease_time_align = server_config.lease;	struct in_addr addr;	init_packet(&packet, oldpacket, DHCPACK);	packet.yiaddr = yiaddr;	if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {		memcpy(&lease_time_align, lease_time, 4);		lease_time_align = ntohl(lease_time_align);		if (lease_time_align > server_config.lease)			lease_time_align = server_config.lease;		else if (lease_time_align < server_config.min_lease)			lease_time_align = server_config.lease;	}	add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));	curr = server_config.options;	while (curr) {		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)			add_option_string(packet.options, curr->data);		curr = curr->next;	}	add_bootp_options(&packet);	addr.s_addr = packet.yiaddr;	LOG(LOG_INFO, "sending ACK to %s", inet_ntoa(addr));	if (send_packet(&packet, 0) < 0)		return -1;	add_lease(packet.chaddr, packet.yiaddr, lease_time_align);	return 0;}int send_inform(struct dhcpMessage *oldpacket){	struct dhcpMessage packet;	struct option_set *curr;	init_packet(&packet, oldpacket, DHCPACK);	curr = server_config.options;	while (curr) {		if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)			add_option_string(packet.options, curr->data);		curr = curr->next;	}	add_bootp_options(&packet);	return send_packet(&packet, 0);}