diff options
Diffstat (limited to 'networking/udhcp/dhcpd.c')
| -rw-r--r-- | networking/udhcp/dhcpd.c | 265 |
1 files changed, 262 insertions, 3 deletions
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c index dc5d9ff..26fb304 100644 --- a/networking/udhcp/dhcpd.c +++ b/networking/udhcp/dhcpd.c @@ -1,13 +1,24 @@ /* vi: set sw=4 ts=4: */ -/* dhcpd.c - * +/* * udhcp Server * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au> * Chris Trew <ctrew@moreton.com.au> * * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001 * - * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. + * 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 <syslog.h> @@ -17,6 +28,254 @@ #include "options.h" +/* send a packet to gateway_nip using the kernel ip stack */ +static int send_packet_to_relay(struct dhcp_packet *dhcp_pkt) +{ + log1("Forwarding packet to relay"); + + return udhcp_send_kernel_packet(dhcp_pkt, + server_config.server_nip, SERVER_PORT, + dhcp_pkt->gateway_nip, SERVER_PORT); +} + +/* send a packet to a specific mac address and ip address by creating our own ip packet */ +static int send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast) +{ + const uint8_t *chaddr; + uint32_t ciaddr; + + // Was: + //if (force_broadcast) { /* broadcast */ } + //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ } + //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ } + //else { /* unicast to dhcp_pkt->yiaddr */ } + // But this is wrong: yiaddr is _our_ idea what client's IP is + // (for example, from lease file). Client may not know that, + // and may not have UDP socket listening on that IP! + // We should never unicast to dhcp_pkt->yiaddr! + // dhcp_pkt->ciaddr, OTOH, comes from client's request packet, + // and can be used. + + if (force_broadcast + || (dhcp_pkt->flags & htons(BROADCAST_FLAG)) + || !dhcp_pkt->ciaddr + ) { + log1("Broadcasting packet to client"); + ciaddr = INADDR_BROADCAST; + chaddr = MAC_BCAST_ADDR; + } else { + log1("Unicasting packet to client ciaddr"); + ciaddr = dhcp_pkt->ciaddr; + chaddr = dhcp_pkt->chaddr; + } + + return udhcp_send_raw_packet(dhcp_pkt, + /*src*/ server_config.server_nip, SERVER_PORT, + /*dst*/ 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 dhcp_packet *dhcp_pkt, int force_broadcast) +{ + if (dhcp_pkt->gateway_nip) + return send_packet_to_relay(dhcp_pkt); + return send_packet_to_client(dhcp_pkt, force_broadcast); +} + +static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type) +{ + udhcp_init_header(packet, type); + packet->xid = oldpacket->xid; + memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr)); + packet->flags = oldpacket->flags; + packet->gateway_nip = oldpacket->gateway_nip; + packet->ciaddr = oldpacket->ciaddr; + add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server_nip); +} + +/* add in the bootp options */ +static void add_bootp_options(struct dhcp_packet *packet) +{ + packet->siaddr_nip = server_config.siaddr_nip; + 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); +} + +static uint32_t select_lease_time(struct dhcp_packet *packet) +{ + uint32_t lease_time_sec = server_config.max_lease_sec; + uint8_t *lease_time_opt = get_option(packet, DHCP_LEASE_TIME); + if (lease_time_opt) { + move_from_unaligned32(lease_time_sec, lease_time_opt); + lease_time_sec = ntohl(lease_time_sec); + if (lease_time_sec > server_config.max_lease_sec) + lease_time_sec = server_config.max_lease_sec; + if (lease_time_sec < server_config.min_lease_sec) + lease_time_sec = server_config.min_lease_sec; + } + return lease_time_sec; +} + +/* send a DHCP OFFER to a DHCP DISCOVER */ +static int send_offer(struct dhcp_packet *oldpacket) +{ + struct dhcp_packet packet; + uint32_t req_nip; + uint32_t lease_time_sec = server_config.max_lease_sec; + uint32_t static_lease_ip; + uint8_t *req_ip_opt; + const char *p_host_name; + struct option_set *curr; + struct in_addr addr; + + init_packet(&packet, oldpacket, DHCPOFFER); + + static_lease_ip = get_static_nip_by_mac(server_config.static_leases, oldpacket->chaddr); + + /* ADDME: if static, short circuit */ + if (!static_lease_ip) { + struct dyn_lease *lease; + + lease = find_lease_by_mac(oldpacket->chaddr); + /* The client is in our lease/offered table */ + if (lease) { + signed_leasetime_t tmp = lease->expires - time(NULL); + if (tmp >= 0) + lease_time_sec = tmp; + packet.yiaddr = lease->lease_nip; + } + /* Or the client has requested an IP */ + else if ((req_ip_opt = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL + /* (read IP) */ + && (move_from_unaligned32(req_nip, req_ip_opt), 1) + /* and the IP is in the lease range */ + && ntohl(req_nip) >= server_config.start_ip + && ntohl(req_nip) <= server_config.end_ip + /* and is not already taken/offered */ + && (!(lease = find_lease_by_nip(req_nip)) + /* or its taken, but expired */ + || is_expired_lease(lease)) + ) { + packet.yiaddr = req_nip; + } + /* Otherwise, find a free IP */ + else { + packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr); + } + + if (!packet.yiaddr) { + bb_error_msg("no IP addresses to give - OFFER abandoned"); + return -1; + } + p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME); + if (add_lease(packet.chaddr, packet.yiaddr, + server_config.offer_time, + p_host_name, + p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0 + ) == 0 + ) { + bb_error_msg("lease pool is full - OFFER abandoned"); + return -1; + } + lease_time_sec = select_lease_time(oldpacket); + } else { + /* It is a static lease... use it */ + packet.yiaddr = static_lease_ip; + } + + add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec)); + + 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); +} + +static int send_NAK(struct dhcp_packet *oldpacket) +{ + struct dhcp_packet packet; + + init_packet(&packet, oldpacket, DHCPNAK); + + log1("Sending NAK"); + return send_packet(&packet, 1); +} + +static int send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr) +{ + struct dhcp_packet packet; + struct option_set *curr; + uint32_t lease_time_sec; + struct in_addr addr; + const char *p_host_name; + + init_packet(&packet, oldpacket, DHCPACK); + packet.yiaddr = yiaddr; + + lease_time_sec = select_lease_time(oldpacket); + + add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec)); + + 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; + + p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME); + add_lease(packet.chaddr, packet.yiaddr, + lease_time_sec, + p_host_name, + p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0 + ); + if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) { + /* rewrite the file with leases at every new acceptance */ + write_leases(); + } + + return 0; +} + +static int send_inform(struct dhcp_packet *oldpacket) +{ + struct dhcp_packet 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); +} + + /* globals */ struct dyn_lease *g_leases; /* struct server_config_t server_config is in bb_common_bufsiz1 */ |