| /* vi: set sw=4 ts=4: */ |
| /* 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 "common.h" |
| #include "dhcpd.h" |
| #include "options.h" |
| |
| |
| /* send a packet to giaddr using the kernel ip stack */ |
| static int send_packet_to_relay(struct dhcpMessage *payload) |
| { |
| DEBUG("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) |
| { |
| const uint8_t *chaddr; |
| uint32_t ciaddr; |
| |
| if (force_broadcast) { |
| DEBUG("broadcasting packet to client (NAK)"); |
| ciaddr = INADDR_BROADCAST; |
| chaddr = MAC_BCAST_ADDR; |
| } else if (payload->ciaddr) { |
| DEBUG("unicasting packet to client ciaddr"); |
| ciaddr = payload->ciaddr; |
| chaddr = payload->chaddr; |
| } else if (ntohs(payload->flags) & BROADCAST_FLAG) { |
| DEBUG("broadcasting packet to client (requested)"); |
| ciaddr = INADDR_BROADCAST; |
| chaddr = MAC_BCAST_ADDR; |
| } else { |
| DEBUG("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 */ |
| lease = find_lease_by_chaddr(oldpacket->chaddr); |
| if (lease) { |
| 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) { |
| bb_error_msg("no IP addresses to give - OFFER abandoned"); |
| return -1; |
| } |
| if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) { |
| bb_error_msg("lease pool is full - OFFER abandoned"); |
| return -1; |
| } |
| lease_time = get_option(oldpacket, DHCP_LEASE_TIME); |
| if (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; |
| bb_info_msg("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("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; |
| bb_info_msg("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); |
| } |