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>
20 uint8_t blank_chaddr[] = {[0 ... 15] = 0};
22 /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
23 void clear_lease(uint8_t *chaddr, uint32_t yiaddr)
27 for (j = 0; j < 16 && !chaddr[j]; j++);
29 for (i = 0; i < server_config.max_leases; i++)
30 if ((j != 16 && !memcmp(leases[i].chaddr, chaddr, 16)) ||
31 (yiaddr && leases[i].yiaddr == yiaddr)) {
32 memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
37 /* add a lease into the table, clearing out any old ones */
38 struct dhcpOfferedAddr *add_lease(uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
40 struct dhcpOfferedAddr *oldest;
42 /* clean out any old ones */
43 clear_lease(chaddr, yiaddr);
45 oldest = oldest_expired_lease();
48 memcpy(oldest->chaddr, chaddr, 16);
49 oldest->yiaddr = yiaddr;
50 oldest->expires = time(0) + lease;
57 /* true if a lease has expired */
58 int lease_expired(struct dhcpOfferedAddr *lease)
60 return (lease->expires < (unsigned long) time(0));
64 /* Find the oldest expired lease, NULL if there are no expired leases */
65 struct dhcpOfferedAddr *oldest_expired_lease(void)
67 struct dhcpOfferedAddr *oldest = NULL;
68 unsigned long oldest_lease = time(0);
72 for (i = 0; i < server_config.max_leases; i++)
73 if (oldest_lease > leases[i].expires) {
74 oldest_lease = leases[i].expires;
75 oldest = &(leases[i]);
82 /* Find the first lease that matches chaddr, NULL if no match */
83 struct dhcpOfferedAddr *find_lease_by_chaddr(uint8_t *chaddr)
87 for (i = 0; i < server_config.max_leases; i++)
88 if (!memcmp(leases[i].chaddr, chaddr, 16)) return &(leases[i]);
94 /* Find the first lease that matches yiaddr, NULL is no match */
95 struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
99 for (i = 0; i < server_config.max_leases; i++)
100 if (leases[i].yiaddr == yiaddr) return &(leases[i]);
106 /* check is an IP is taken, if it is, add it to the lease table */
107 static int check_ip(uint32_t addr)
111 if (arpping(addr, server_config.server, server_config.arp, server_config.interface) == 0) {
113 LOG(LOG_INFO, "%s belongs to someone, reserving it for %ld seconds",
114 inet_ntoa(temp), server_config.conflict_time);
115 add_lease(blank_chaddr, addr, server_config.conflict_time);
121 /* find an assignable address, it check_expired is true, we check all the expired leases as well.
122 * Maybe this should try expired leases by age... */
123 uint32_t find_address(int check_expired)
126 struct dhcpOfferedAddr *lease = NULL;
128 addr = ntohl(server_config.start); /* addr is in host order here */
129 for (;addr <= ntohl(server_config.end); addr++) {
131 /* ie, 192.168.55.0 */
132 if (!(addr & 0xFF)) continue;
134 /* ie, 192.168.55.255 */
135 if ((addr & 0xFF) == 0xFF) continue;
137 /* lease is not taken */
139 if ((!(lease = find_lease_by_yiaddr(ret)) ||
141 /* or it expired and we are checking for expired leases */
142 (check_expired && lease_expired(lease))) &&
144 /* and it isn't on the network */