1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
|
/* 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.
*/
#include <syslog.h>
#include "common.h"
#include "dhcpd.h"
#include "options.h"
/* globals */
struct dhcpOfferedAddr *leases;
struct server_config_t server_config;
int udhcpd_main(int argc, char **argv);
int udhcpd_main(int argc, char **argv)
{
fd_set rfds;
struct timeval tv;
int server_socket = -1, bytes, retval, max_sock;
struct dhcpMessage packet;
uint8_t *state, *server_id, *requested;
uint32_t server_id_align, requested_align, static_lease_ip;
unsigned timeout_end;
unsigned num_ips;
unsigned opt;
struct option_set *option;
struct dhcpOfferedAddr *lease, static_lease;
opt = getopt32(argc, argv, "fS");
if (!(opt & 1)) { /* no -f */
bb_daemonize_or_rexec(0, argv);
logmode &= ~LOGMODE_STDIO;
}
if (opt & 2) { /* -S */
openlog(applet_name, LOG_PID, LOG_LOCAL0);
logmode |= LOGMODE_SYSLOG;
}
/* Would rather not do read_config before daemonization -
* otherwise NOMMU machines will parse config twice */
read_config(argv[1] ? argv[1] : DHCPD_CONF_FILE);
/* Make sure fd 0,1,2 are open */
bb_sanitize_stdio();
/* Equivalent of doing a fflush after every \n */
setlinebuf(stdout);
/* Create pidfile */
write_pidfile(server_config.pidfile);
/* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
bb_info_msg("%s (v%s) started", applet_name, BB_VER);
option = find_option(server_config.options, DHCP_LEASE_TIME);
server_config.lease = LEASE_TIME;
if (option) {
memcpy(&server_config.lease, option->data + 2, 4);
server_config.lease = ntohl(server_config.lease);
}
/* Sanity check */
num_ips = server_config.end_ip - server_config.start_ip + 1;
if (server_config.max_leases > num_ips) {
bb_error_msg("max_leases=%u is too big, setting to %u",
(unsigned)server_config.max_leases, num_ips);
server_config.max_leases = num_ips;
}
leases = xzalloc(server_config.max_leases * sizeof(*leases));
read_leases(server_config.lease_file);
if (read_interface(server_config.interface, &server_config.ifindex,
&server_config.server, server_config.arp)) {
retval = 1;
goto ret;
}
/* Setup the signal pipe */
udhcp_sp_setup();
timeout_end = monotonic_sec() + server_config.auto_time;
while (1) { /* loop until universe collapses */
if (server_socket < 0) {
server_socket = listen_socket(INADDR_ANY, SERVER_PORT,
server_config.interface);
}
max_sock = udhcp_sp_fd_set(&rfds, server_socket);
if (server_config.auto_time) {
tv.tv_sec = timeout_end - monotonic_sec();
tv.tv_usec = 0;
}
retval = 0;
if (!server_config.auto_time || tv.tv_sec > 0) {
retval = select(max_sock + 1, &rfds, NULL, NULL,
server_config.auto_time ? &tv : NULL);
}
if (retval == 0) {
write_leases();
timeout_end = monotonic_sec() + server_config.auto_time;
continue;
}
if (retval < 0 && errno != EINTR) {
DEBUG("error on select");
continue;
}
switch (udhcp_sp_read(&rfds)) {
case SIGUSR1:
bb_info_msg("Received a SIGUSR1");
write_leases();
/* why not just reset the timeout, eh */
timeout_end = monotonic_sec() + server_config.auto_time;
continue;
case SIGTERM:
bb_info_msg("Received a SIGTERM");
goto ret0;
case 0: break; /* no signal */
default: continue; /* signal or error (probably EINTR) */
}
bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */
if (bytes < 0) {
if (bytes == -1 && errno != EINTR) {
DEBUG("error on read, %s, reopening socket", strerror(errno));
close(server_socket);
server_socket = -1;
}
continue;
}
state = get_option(&packet, DHCP_MESSAGE_TYPE);
if (state == NULL) {
bb_error_msg("cannot get option from packet, ignoring");
continue;
}
/* Look for a static lease */
static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
if (static_lease_ip) {
bb_info_msg("Found static lease: %x", static_lease_ip);
memcpy(&static_lease.chaddr, &packet.chaddr, 16);
static_lease.yiaddr = static_lease_ip;
static_lease.expires = 0;
lease = &static_lease;
} else {
lease = find_lease_by_chaddr(packet.chaddr);
}
switch (state[0]) {
case DHCPDISCOVER:
DEBUG("Received DISCOVER");
if (sendOffer(&packet) < 0) {
bb_error_msg("send OFFER failed");
}
break;
case DHCPREQUEST:
DEBUG("received REQUEST");
requested = get_option(&packet, DHCP_REQUESTED_IP);
server_id = get_option(&packet, DHCP_SERVER_ID);
if (requested) memcpy(&requested_align, requested, 4);
if (server_id) memcpy(&server_id_align, server_id, 4);
if (lease) {
if (server_id) {
/* SELECTING State */
DEBUG("server_id = %08x", ntohl(server_id_align));
if (server_id_align == server_config.server && requested
&& requested_align == lease->yiaddr
) {
sendACK(&packet, lease->yiaddr);
}
} else if (requested) {
/* INIT-REBOOT State */
if (lease->yiaddr == requested_align)
sendACK(&packet, lease->yiaddr);
else
sendNAK(&packet);
} else if (lease->yiaddr == packet.ciaddr) {
/* RENEWING or REBINDING State */
sendACK(&packet, lease->yiaddr);
} else {
/* don't know what to do!!!! */
sendNAK(&packet);
}
/* what to do if we have no record of the client */
} else if (server_id) {
/* SELECTING State */
} else if (requested) {
/* INIT-REBOOT State */
lease = find_lease_by_yiaddr(requested_align);
if (lease) {
if (lease_expired(lease)) {
/* probably best if we drop this lease */
memset(lease->chaddr, 0, 16);
/* make some contention for this address */
} else
sendNAK(&packet);
} else {
uint32_t r = ntohl(requested_align);
if (r < server_config.start_ip
|| r > server_config.end_ip
) {
sendNAK(&packet);
}
/* else remain silent */
}
} else {
/* RENEWING or REBINDING State */
}
break;
case DHCPDECLINE:
DEBUG("Received DECLINE");
if (lease) {
memset(lease->chaddr, 0, 16);
lease->expires = time(0) + server_config.decline_time;
}
break;
case DHCPRELEASE:
DEBUG("Received RELEASE");
if (lease)
lease->expires = time(0);
break;
case DHCPINFORM:
DEBUG("Received INFORM");
send_inform(&packet);
break;
default:
bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
}
}
ret0:
retval = 0;
ret:
/*if (server_config.pidfile) - server_config.pidfile is never NULL */
remove_pidfile(server_config.pidfile);
return retval;
}
|
