source: MondoRescue/branches/stable/mindi-busybox/networking/udhcp/serverpacket.c @ 821

Last change on this file since 821 was 821, checked in by Bruno Cornec, 14 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 7.7 KB
Line 
1/* serverpacket.c
2 *
3 * Construct and send DHCP server packets
4 *
5 * Russ Dill <Russ.Dill@asu.edu> July 2001
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <sys/socket.h>
23#include <netinet/in.h>
24#include <arpa/inet.h>
25#include <string.h>
26#include <time.h>
27
28#include "common.h"
29#include "serverpacket.h"
30#include "dhcpd.h"
31#include "options.h"
32#include "static_leases.h"
33
34/* send a packet to giaddr using the kernel ip stack */
35static int send_packet_to_relay(struct dhcpMessage *payload)
36{
37    DEBUG(LOG_INFO, "Forwarding packet to relay");
38
39    return udhcp_kernel_packet(payload, server_config.server, SERVER_PORT,
40            payload->giaddr, SERVER_PORT);
41}
42
43
44/* send a packet to a specific arp address and ip address by creating our own ip packet */
45static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcast)
46{
47    uint8_t *chaddr;
48    uint32_t ciaddr;
49
50    if (force_broadcast) {
51        DEBUG(LOG_INFO, "broadcasting packet to client (NAK)");
52        ciaddr = INADDR_BROADCAST;
53        chaddr = MAC_BCAST_ADDR;
54    } else if (payload->ciaddr) {
55        DEBUG(LOG_INFO, "unicasting packet to client ciaddr");
56        ciaddr = payload->ciaddr;
57        chaddr = payload->chaddr;
58    } else if (ntohs(payload->flags) & BROADCAST_FLAG) {
59        DEBUG(LOG_INFO, "broadcasting packet to client (requested)");
60        ciaddr = INADDR_BROADCAST;
61        chaddr = MAC_BCAST_ADDR;
62    } else {
63        DEBUG(LOG_INFO, "unicasting packet to client yiaddr");
64        ciaddr = payload->yiaddr;
65        chaddr = payload->chaddr;
66    }
67    return udhcp_raw_packet(payload, server_config.server, SERVER_PORT,
68            ciaddr, CLIENT_PORT, chaddr, server_config.ifindex);
69}
70
71
72/* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
73static int send_packet(struct dhcpMessage *payload, int force_broadcast)
74{
75    int ret;
76
77    if (payload->giaddr)
78        ret = send_packet_to_relay(payload);
79    else ret = send_packet_to_client(payload, force_broadcast);
80    return ret;
81}
82
83
84static void init_packet(struct dhcpMessage *packet, struct dhcpMessage *oldpacket, char type)
85{
86    udhcp_init_header(packet, type);
87    packet->xid = oldpacket->xid;
88    memcpy(packet->chaddr, oldpacket->chaddr, 16);
89    packet->flags = oldpacket->flags;
90    packet->giaddr = oldpacket->giaddr;
91    packet->ciaddr = oldpacket->ciaddr;
92    add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server);
93}
94
95
96/* add in the bootp options */
97static void add_bootp_options(struct dhcpMessage *packet)
98{
99    packet->siaddr = server_config.siaddr;
100    if (server_config.sname)
101        strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
102    if (server_config.boot_file)
103        strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
104}
105
106
107/* send a DHCP OFFER to a DHCP DISCOVER */
108int sendOffer(struct dhcpMessage *oldpacket)
109{
110    struct dhcpMessage packet;
111    struct dhcpOfferedAddr *lease = NULL;
112    uint32_t req_align, lease_time_align = server_config.lease;
113    uint8_t *req, *lease_time;
114    struct option_set *curr;
115    struct in_addr addr;
116
117    uint32_t static_lease_ip;
118
119    init_packet(&packet, oldpacket, DHCPOFFER);
120
121    static_lease_ip = getIpByMac(server_config.static_leases, oldpacket->chaddr);
122
123    /* ADDME: if static, short circuit */
124    if(!static_lease_ip)
125    {
126    /* the client is in our lease/offered table */
127    if ((lease = find_lease_by_chaddr(oldpacket->chaddr))) {
128        if (!lease_expired(lease))
129            lease_time_align = lease->expires - time(0);
130        packet.yiaddr = lease->yiaddr;
131
132    /* Or the client has a requested ip */
133    } else if ((req = get_option(oldpacket, DHCP_REQUESTED_IP)) &&
134
135           /* Don't look here (ugly hackish thing to do) */
136           memcpy(&req_align, req, 4) &&
137
138           /* and the ip is in the lease range */
139           ntohl(req_align) >= ntohl(server_config.start) &&
140           ntohl(req_align) <= ntohl(server_config.end) &&
141
142            !static_lease_ip &&  /* Check that its not a static lease */
143            /* and is not already taken/offered */
144           ((!(lease = find_lease_by_yiaddr(req_align)) ||
145
146           /* or its taken, but expired */ /* ADDME: or maybe in here */
147           lease_expired(lease)))) {
148                packet.yiaddr = req_align; /* FIXME: oh my, is there a host using this IP? */
149
150            /* otherwise, find a free IP */
151    } else {
152            /* Is it a static lease? (No, because find_address skips static lease) */
153        packet.yiaddr = find_address(0);
154
155        /* try for an expired lease */
156        if (!packet.yiaddr) packet.yiaddr = find_address(1);
157    }
158
159    if(!packet.yiaddr) {
160        LOG(LOG_WARNING, "no IP addresses to give -- OFFER abandoned");
161        return -1;
162    }
163
164    if (!add_lease(packet.chaddr, packet.yiaddr, server_config.offer_time)) {
165        LOG(LOG_WARNING, "lease pool is full -- OFFER abandoned");
166        return -1;
167    }
168
169    if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
170        memcpy(&lease_time_align, lease_time, 4);
171        lease_time_align = ntohl(lease_time_align);
172        if (lease_time_align > server_config.lease)
173            lease_time_align = server_config.lease;
174    }
175
176    /* Make sure we aren't just using the lease time from the previous offer */
177    if (lease_time_align < server_config.min_lease)
178        lease_time_align = server_config.lease;
179    }
180    /* ADDME: end of short circuit */
181    else
182    {
183        /* It is a static lease... use it */
184        packet.yiaddr = static_lease_ip;
185    }
186
187    add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
188
189    curr = server_config.options;
190    while (curr) {
191        if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
192            add_option_string(packet.options, curr->data);
193        curr = curr->next;
194    }
195
196    add_bootp_options(&packet);
197
198    addr.s_addr = packet.yiaddr;
199    LOG(LOG_INFO, "sending OFFER of %s", inet_ntoa(addr));
200    return send_packet(&packet, 0);
201}
202
203
204int sendNAK(struct dhcpMessage *oldpacket)
205{
206    struct dhcpMessage packet;
207
208    init_packet(&packet, oldpacket, DHCPNAK);
209
210    DEBUG(LOG_INFO, "sending NAK");
211    return send_packet(&packet, 1);
212}
213
214
215int sendACK(struct dhcpMessage *oldpacket, uint32_t yiaddr)
216{
217    struct dhcpMessage packet;
218    struct option_set *curr;
219    uint8_t *lease_time;
220    uint32_t lease_time_align = server_config.lease;
221    struct in_addr addr;
222
223    init_packet(&packet, oldpacket, DHCPACK);
224    packet.yiaddr = yiaddr;
225
226    if ((lease_time = get_option(oldpacket, DHCP_LEASE_TIME))) {
227        memcpy(&lease_time_align, lease_time, 4);
228        lease_time_align = ntohl(lease_time_align);
229        if (lease_time_align > server_config.lease)
230            lease_time_align = server_config.lease;
231        else if (lease_time_align < server_config.min_lease)
232            lease_time_align = server_config.lease;
233    }
234
235    add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_align));
236
237    curr = server_config.options;
238    while (curr) {
239        if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
240            add_option_string(packet.options, curr->data);
241        curr = curr->next;
242    }
243
244    add_bootp_options(&packet);
245
246    addr.s_addr = packet.yiaddr;
247    LOG(LOG_INFO, "sending ACK to %s", inet_ntoa(addr));
248
249    if (send_packet(&packet, 0) < 0)
250        return -1;
251
252    add_lease(packet.chaddr, packet.yiaddr, lease_time_align);
253
254    return 0;
255}
256
257
258int send_inform(struct dhcpMessage *oldpacket)
259{
260    struct dhcpMessage packet;
261    struct option_set *curr;
262
263    init_packet(&packet, oldpacket, DHCPACK);
264
265    curr = server_config.options;
266    while (curr) {
267        if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
268            add_option_string(packet.options, curr->data);
269        curr = curr->next;
270    }
271
272    add_bootp_options(&packet);
273
274    return send_packet(&packet, 0);
275}
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