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-rw-r--r--networking/udhcp/dhcpd.c265
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 */