2 * leases.c -- tools to manage DHCP leases
3 * Russ Dill <Russ.Dill@asu.edu> July 2001
8 #include <sys/socket.h>
9 #include <netinet/in.h>
10 #include <arpa/inet.h>
19 unsigned char blank_chaddr[] = {[0 ... 15] = 0};
21 /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
22 void clear_lease(u_int8_t *chaddr, u_int32_t yiaddr)
26 for (j = 0; j < 16 && !chaddr[j]; j++);
28 for (i = 0; i < server_config.max_leases; i++)
29 if ((j != 16 && !memcmp(leases[i].chaddr, chaddr, 16)) ||
30 (yiaddr && leases[i].yiaddr == yiaddr)) {
31 memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
36 /* add a lease into the table, clearing out any old ones */
37 struct dhcpOfferedAddr *add_lease(u_int8_t *chaddr, u_int32_t yiaddr, unsigned long lease)
39 struct dhcpOfferedAddr *oldest;
41 /* clean out any old ones */
42 clear_lease(chaddr, yiaddr);
44 oldest = oldest_expired_lease();
47 memcpy(oldest->chaddr, chaddr, 16);
48 oldest->yiaddr = yiaddr;
49 oldest->expires = time(0) + lease;
56 /* true if a lease has expired */
57 int lease_expired(struct dhcpOfferedAddr *lease)
59 return (lease->expires < (unsigned long) time(0));
63 /* Find the oldest expired lease, NULL if there are no expired leases */
64 struct dhcpOfferedAddr *oldest_expired_lease(void)
66 struct dhcpOfferedAddr *oldest = NULL;
67 unsigned long oldest_lease = time(0);
71 for (i = 0; i < server_config.max_leases; i++)
72 if (oldest_lease > leases[i].expires) {
73 oldest_lease = leases[i].expires;
74 oldest = &(leases[i]);
81 /* Find the first lease that matches chaddr, NULL if no match */
82 struct dhcpOfferedAddr *find_lease_by_chaddr(u_int8_t *chaddr)
86 for (i = 0; i < server_config.max_leases; i++)
87 if (!memcmp(leases[i].chaddr, chaddr, 16)) return &(leases[i]);
93 /* Find the first lease that matches yiaddr, NULL is no match */
94 struct dhcpOfferedAddr *find_lease_by_yiaddr(u_int32_t yiaddr)
98 for (i = 0; i < server_config.max_leases; i++)
99 if (leases[i].yiaddr == yiaddr) return &(leases[i]);
105 /* find an assignable address, it check_expired is true, we check all the expired leases as well.
106 * Maybe this should try expired leases by age... */
107 u_int32_t find_address(int check_expired)
110 struct dhcpOfferedAddr *lease = NULL;
112 addr = ntohl(server_config.start); /* addr is in host order here */
113 for (;addr <= ntohl(server_config.end); addr++) {
115 /* ie, 192.168.55.0 */
116 if (!(addr & 0xFF)) continue;
118 /* ie, 192.168.55.255 */
119 if ((addr & 0xFF) == 0xFF) continue;
121 /* lease is not taken */
123 if ((!(lease = find_lease_by_yiaddr(ret)) ||
125 /* or it expired and we are checking for expired leases */
126 (check_expired && lease_expired(lease))) &&
128 /* and it isn't on the network */
138 /* check is an IP is taken, if it is, add it to the lease table */
139 int check_ip(u_int32_t addr)
143 if (arpping(addr, server_config.server, server_config.arp, server_config.interface) == 0) {
145 LOG(LOG_INFO, "%s belongs to someone, reserving it for %ld seconds",
146 inet_ntoa(temp), server_config.conflict_time);
147 add_lease(blank_chaddr, addr, server_config.conflict_time);