1 | /*
|
---|
2 | * leases.c -- tools to manage DHCP leases
|
---|
3 | * Russ Dill <Russ.Dill@asu.edu> July 2001
|
---|
4 | */
|
---|
5 |
|
---|
6 | #include <time.h>
|
---|
7 | #include <string.h>
|
---|
8 | #include <sys/socket.h>
|
---|
9 | #include <netinet/in.h>
|
---|
10 | #include <arpa/inet.h>
|
---|
11 |
|
---|
12 | #include "dhcpd.h"
|
---|
13 | #include "files.h"
|
---|
14 | #include "options.h"
|
---|
15 | #include "leases.h"
|
---|
16 | #include "arpping.h"
|
---|
17 | #include "common.h"
|
---|
18 |
|
---|
19 | #include "static_leases.h"
|
---|
20 |
|
---|
21 |
|
---|
22 | uint8_t blank_chaddr[] = {[0 ... 15] = 0};
|
---|
23 |
|
---|
24 | /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
|
---|
25 | void clear_lease(uint8_t *chaddr, uint32_t yiaddr)
|
---|
26 | {
|
---|
27 | unsigned int i, j;
|
---|
28 |
|
---|
29 | for (j = 0; j < 16 && !chaddr[j]; j++);
|
---|
30 |
|
---|
31 | for (i = 0; i < server_config.max_leases; i++)
|
---|
32 | if ((j != 16 && !memcmp(leases[i].chaddr, chaddr, 16)) ||
|
---|
33 | (yiaddr && leases[i].yiaddr == yiaddr)) {
|
---|
34 | memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
|
---|
35 | }
|
---|
36 | }
|
---|
37 |
|
---|
38 |
|
---|
39 | /* add a lease into the table, clearing out any old ones */
|
---|
40 | struct dhcpOfferedAddr *add_lease(uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
|
---|
41 | {
|
---|
42 | struct dhcpOfferedAddr *oldest;
|
---|
43 |
|
---|
44 | /* clean out any old ones */
|
---|
45 | clear_lease(chaddr, yiaddr);
|
---|
46 |
|
---|
47 | oldest = oldest_expired_lease();
|
---|
48 |
|
---|
49 | if (oldest) {
|
---|
50 | memcpy(oldest->chaddr, chaddr, 16);
|
---|
51 | oldest->yiaddr = yiaddr;
|
---|
52 | oldest->expires = time(0) + lease;
|
---|
53 | }
|
---|
54 |
|
---|
55 | return oldest;
|
---|
56 | }
|
---|
57 |
|
---|
58 |
|
---|
59 | /* true if a lease has expired */
|
---|
60 | int lease_expired(struct dhcpOfferedAddr *lease)
|
---|
61 | {
|
---|
62 | return (lease->expires < (unsigned long) time(0));
|
---|
63 | }
|
---|
64 |
|
---|
65 |
|
---|
66 | /* Find the oldest expired lease, NULL if there are no expired leases */
|
---|
67 | struct dhcpOfferedAddr *oldest_expired_lease(void)
|
---|
68 | {
|
---|
69 | struct dhcpOfferedAddr *oldest = NULL;
|
---|
70 | unsigned long oldest_lease = time(0);
|
---|
71 | unsigned int i;
|
---|
72 |
|
---|
73 |
|
---|
74 | for (i = 0; i < server_config.max_leases; i++)
|
---|
75 | if (oldest_lease > leases[i].expires) {
|
---|
76 | oldest_lease = leases[i].expires;
|
---|
77 | oldest = &(leases[i]);
|
---|
78 | }
|
---|
79 | return oldest;
|
---|
80 |
|
---|
81 | }
|
---|
82 |
|
---|
83 |
|
---|
84 | /* Find the first lease that matches chaddr, NULL if no match */
|
---|
85 | struct dhcpOfferedAddr *find_lease_by_chaddr(uint8_t *chaddr)
|
---|
86 | {
|
---|
87 | unsigned int i;
|
---|
88 |
|
---|
89 | for (i = 0; i < server_config.max_leases; i++)
|
---|
90 | if (!memcmp(leases[i].chaddr, chaddr, 16)) return &(leases[i]);
|
---|
91 |
|
---|
92 | return NULL;
|
---|
93 | }
|
---|
94 |
|
---|
95 |
|
---|
96 | /* Find the first lease that matches yiaddr, NULL is no match */
|
---|
97 | struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
|
---|
98 | {
|
---|
99 | unsigned int i;
|
---|
100 |
|
---|
101 | for (i = 0; i < server_config.max_leases; i++)
|
---|
102 | if (leases[i].yiaddr == yiaddr) return &(leases[i]);
|
---|
103 |
|
---|
104 | return NULL;
|
---|
105 | }
|
---|
106 |
|
---|
107 |
|
---|
108 | /* check is an IP is taken, if it is, add it to the lease table */
|
---|
109 | static int check_ip(uint32_t addr)
|
---|
110 | {
|
---|
111 | struct in_addr temp;
|
---|
112 |
|
---|
113 | if (arpping(addr, server_config.server, server_config.arp, server_config.interface) == 0) {
|
---|
114 | temp.s_addr = addr;
|
---|
115 | LOG(LOG_INFO, "%s belongs to someone, reserving it for %ld seconds",
|
---|
116 | inet_ntoa(temp), server_config.conflict_time);
|
---|
117 | add_lease(blank_chaddr, addr, server_config.conflict_time);
|
---|
118 | return 1;
|
---|
119 | } else return 0;
|
---|
120 | }
|
---|
121 |
|
---|
122 |
|
---|
123 | /* find an assignable address, it check_expired is true, we check all the expired leases as well.
|
---|
124 | * Maybe this should try expired leases by age... */
|
---|
125 | uint32_t find_address(int check_expired)
|
---|
126 | {
|
---|
127 | uint32_t addr, ret;
|
---|
128 | struct dhcpOfferedAddr *lease = NULL;
|
---|
129 |
|
---|
130 | addr = ntohl(server_config.start); /* addr is in host order here */
|
---|
131 | for (;addr <= ntohl(server_config.end); addr++) {
|
---|
132 |
|
---|
133 | /* ie, 192.168.55.0 */
|
---|
134 | if (!(addr & 0xFF)) continue;
|
---|
135 |
|
---|
136 | /* ie, 192.168.55.255 */
|
---|
137 | if ((addr & 0xFF) == 0xFF) continue;
|
---|
138 |
|
---|
139 | /* Only do if it isn't an assigned as a static lease */
|
---|
140 | if(!reservedIp(server_config.static_leases, htonl(addr)))
|
---|
141 | {
|
---|
142 |
|
---|
143 | /* lease is not taken */
|
---|
144 | ret = htonl(addr);
|
---|
145 | if ((!(lease = find_lease_by_yiaddr(ret)) ||
|
---|
146 |
|
---|
147 | /* or it expired and we are checking for expired leases */
|
---|
148 | (check_expired && lease_expired(lease))) &&
|
---|
149 |
|
---|
150 | /* and it isn't on the network */
|
---|
151 | !check_ip(ret)) {
|
---|
152 | return ret;
|
---|
153 | break;
|
---|
154 | }
|
---|
155 | }
|
---|
156 | }
|
---|
157 | return 0;
|
---|
158 | }
|
---|