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-rw-r--r--networking/udhcp/serverpacket.c283
1 files changed, 0 insertions, 283 deletions
diff --git a/networking/udhcp/serverpacket.c b/networking/udhcp/serverpacket.c
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--- a/networking/udhcp/serverpacket.c
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1/* vi: set sw=4 ts=4: */
2/* serverpacket.c
3 *
4 * Construct and send DHCP server packets
5 *
6 * Russ Dill <Russ.Dill@asu.edu> July 2001
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 */
22
23#include "common.h"
24#include "dhcpc.h"
25#include "dhcpd.h"
26#include "options.h"
27
28
29/* send a packet to gateway_nip using the kernel ip stack */
30static int send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
31{
32 log1("Forwarding packet to relay");
33
34 return udhcp_send_kernel_packet(dhcp_pkt,
35 server_config.server_nip, SERVER_PORT,
36 dhcp_pkt->gateway_nip, SERVER_PORT);
37}
38
39
40/* send a packet to a specific mac address and ip address by creating our own ip packet */
41static int send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
42{
43 const uint8_t *chaddr;
44 uint32_t ciaddr;
45
46 // Was:
47 //if (force_broadcast) { /* broadcast */ }
48 //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ }
49 //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ }
50 //else { /* unicast to dhcp_pkt->yiaddr */ }
51 // But this is wrong: yiaddr is _our_ idea what client's IP is
52 // (for example, from lease file). Client may not know that,
53 // and may not have UDP socket listening on that IP!
54 // We should never unicast to dhcp_pkt->yiaddr!
55 // dhcp_pkt->ciaddr, OTOH, comes from client's request packet,
56 // and can be used.
57
58 if (force_broadcast
59 || (dhcp_pkt->flags & htons(BROADCAST_FLAG))
60 || !dhcp_pkt->ciaddr
61 ) {
62 log1("Broadcasting packet to client");
63 ciaddr = INADDR_BROADCAST;
64 chaddr = MAC_BCAST_ADDR;
65 } else {
66 log1("Unicasting packet to client ciaddr");
67 ciaddr = dhcp_pkt->ciaddr;
68 chaddr = dhcp_pkt->chaddr;
69 }
70
71 return udhcp_send_raw_packet(dhcp_pkt,
72 /*src*/ server_config.server_nip, SERVER_PORT,
73 /*dst*/ ciaddr, CLIENT_PORT, chaddr,
74 server_config.ifindex);
75}
76
77
78/* send a dhcp packet, if force broadcast is set, the packet will be broadcast to the client */
79static int send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
80{
81 if (dhcp_pkt->gateway_nip)
82 return send_packet_to_relay(dhcp_pkt);
83 return send_packet_to_client(dhcp_pkt, force_broadcast);
84}
85
86
87static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type)
88{
89 udhcp_init_header(packet, type);
90 packet->xid = oldpacket->xid;
91 memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
92 packet->flags = oldpacket->flags;
93 packet->gateway_nip = oldpacket->gateway_nip;
94 packet->ciaddr = oldpacket->ciaddr;
95 add_simple_option(packet->options, DHCP_SERVER_ID, server_config.server_nip);
96}
97
98
99/* add in the bootp options */
100static void add_bootp_options(struct dhcp_packet *packet)
101{
102 packet->siaddr_nip = server_config.siaddr_nip;
103 if (server_config.sname)
104 strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
105 if (server_config.boot_file)
106 strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
107}
108
109
110static uint32_t select_lease_time(struct dhcp_packet *packet)
111{
112 uint32_t lease_time_sec = server_config.max_lease_sec;
113 uint8_t *lease_time_opt = get_option(packet, DHCP_LEASE_TIME);
114 if (lease_time_opt) {
115 move_from_unaligned32(lease_time_sec, lease_time_opt);
116 lease_time_sec = ntohl(lease_time_sec);
117 if (lease_time_sec > server_config.max_lease_sec)
118 lease_time_sec = server_config.max_lease_sec;
119 if (lease_time_sec < server_config.min_lease_sec)
120 lease_time_sec = server_config.min_lease_sec;
121 }
122 return lease_time_sec;
123}
124
125
126/* send a DHCP OFFER to a DHCP DISCOVER */
127int FAST_FUNC send_offer(struct dhcp_packet *oldpacket)
128{
129 struct dhcp_packet packet;
130 uint32_t req_nip;
131 uint32_t lease_time_sec = server_config.max_lease_sec;
132 uint32_t static_lease_ip;
133 uint8_t *req_ip_opt;
134 const char *p_host_name;
135 struct option_set *curr;
136 struct in_addr addr;
137
138 init_packet(&packet, oldpacket, DHCPOFFER);
139
140 static_lease_ip = get_static_nip_by_mac(server_config.static_leases, oldpacket->chaddr);
141
142 /* ADDME: if static, short circuit */
143 if (!static_lease_ip) {
144 struct dyn_lease *lease;
145
146 lease = find_lease_by_mac(oldpacket->chaddr);
147 /* The client is in our lease/offered table */
148 if (lease) {
149 signed_leasetime_t tmp = lease->expires - time(NULL);
150 if (tmp >= 0)
151 lease_time_sec = tmp;
152 packet.yiaddr = lease->lease_nip;
153 }
154 /* Or the client has requested an IP */
155 else if ((req_ip_opt = get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL
156 /* (read IP) */
157 && (move_from_unaligned32(req_nip, req_ip_opt), 1)
158 /* and the IP is in the lease range */
159 && ntohl(req_nip) >= server_config.start_ip
160 && ntohl(req_nip) <= server_config.end_ip
161 /* and is not already taken/offered */
162 && (!(lease = find_lease_by_nip(req_nip))
163 /* or its taken, but expired */
164 || is_expired_lease(lease))
165 ) {
166 packet.yiaddr = req_nip;
167 }
168 /* Otherwise, find a free IP */
169 else {
170 packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr);
171 }
172
173 if (!packet.yiaddr) {
174 bb_error_msg("no IP addresses to give - OFFER abandoned");
175 return -1;
176 }
177 p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
178 if (add_lease(packet.chaddr, packet.yiaddr,
179 server_config.offer_time,
180 p_host_name,
181 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
182 ) == 0
183 ) {
184 bb_error_msg("lease pool is full - OFFER abandoned");
185 return -1;
186 }
187 lease_time_sec = select_lease_time(oldpacket);
188 } else {
189 /* It is a static lease... use it */
190 packet.yiaddr = static_lease_ip;
191 }
192
193 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
194
195 curr = server_config.options;
196 while (curr) {
197 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
198 add_option_string(packet.options, curr->data);
199 curr = curr->next;
200 }
201
202 add_bootp_options(&packet);
203
204 addr.s_addr = packet.yiaddr;
205 bb_info_msg("Sending OFFER of %s", inet_ntoa(addr));
206 return send_packet(&packet, 0);
207}
208
209
210int FAST_FUNC send_NAK(struct dhcp_packet *oldpacket)
211{
212 struct dhcp_packet packet;
213
214 init_packet(&packet, oldpacket, DHCPNAK);
215
216 log1("Sending NAK");
217 return send_packet(&packet, 1);
218}
219
220
221int FAST_FUNC send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
222{
223 struct dhcp_packet packet;
224 struct option_set *curr;
225 uint32_t lease_time_sec;
226 struct in_addr addr;
227 const char *p_host_name;
228
229 init_packet(&packet, oldpacket, DHCPACK);
230 packet.yiaddr = yiaddr;
231
232 lease_time_sec = select_lease_time(oldpacket);
233
234 add_simple_option(packet.options, DHCP_LEASE_TIME, htonl(lease_time_sec));
235
236 curr = server_config.options;
237 while (curr) {
238 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
239 add_option_string(packet.options, curr->data);
240 curr = curr->next;
241 }
242
243 add_bootp_options(&packet);
244
245 addr.s_addr = packet.yiaddr;
246 bb_info_msg("Sending ACK to %s", inet_ntoa(addr));
247
248 if (send_packet(&packet, 0) < 0)
249 return -1;
250
251 p_host_name = (const char*) get_option(oldpacket, DHCP_HOST_NAME);
252 add_lease(packet.chaddr, packet.yiaddr,
253 lease_time_sec,
254 p_host_name,
255 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
256 );
257 if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
258 /* rewrite the file with leases at every new acceptance */
259 write_leases();
260 }
261
262 return 0;
263}
264
265
266int FAST_FUNC send_inform(struct dhcp_packet *oldpacket)
267{
268 struct dhcp_packet packet;
269 struct option_set *curr;
270
271 init_packet(&packet, oldpacket, DHCPACK);
272
273 curr = server_config.options;
274 while (curr) {
275 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
276 add_option_string(packet.options, curr->data);
277 curr = curr->next;
278 }
279
280 add_bootp_options(&packet);
281
282 return send_packet(&packet, 0);
283}
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