1 /* vi: set sw=4 ts=4: */
3 * leases.c -- tools to manage DHCP leases
4 * Russ Dill <Russ.Dill@asu.edu> July 2001
11 uint8_t blank_chaddr[] = {[0 ... 15] = 0};
13 /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
14 void clear_lease(uint8_t *chaddr, uint32_t yiaddr)
18 for (j = 0; j < 16 && !chaddr[j]; j++);
20 for (i = 0; i < server_config.max_leases; i++)
21 if ((j != 16 && !memcmp(leases[i].chaddr, chaddr, 16)) ||
22 (yiaddr && leases[i].yiaddr == yiaddr)) {
23 memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
28 /* add a lease into the table, clearing out any old ones */
29 struct dhcpOfferedAddr *add_lease(uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
31 struct dhcpOfferedAddr *oldest;
33 /* clean out any old ones */
34 clear_lease(chaddr, yiaddr);
36 oldest = oldest_expired_lease();
39 memcpy(oldest->chaddr, chaddr, 16);
40 oldest->yiaddr = yiaddr;
41 oldest->expires = time(0) + lease;
48 /* true if a lease has expired */
49 int lease_expired(struct dhcpOfferedAddr *lease)
51 return (lease->expires < (unsigned long) time(0));
55 /* Find the oldest expired lease, NULL if there are no expired leases */
56 struct dhcpOfferedAddr *oldest_expired_lease(void)
58 struct dhcpOfferedAddr *oldest = NULL;
59 unsigned long oldest_lease = time(0);
63 for (i = 0; i < server_config.max_leases; i++)
64 if (oldest_lease > leases[i].expires) {
65 oldest_lease = leases[i].expires;
66 oldest = &(leases[i]);
73 /* Find the first lease that matches chaddr, NULL if no match */
74 struct dhcpOfferedAddr *find_lease_by_chaddr(uint8_t *chaddr)
78 for (i = 0; i < server_config.max_leases; i++)
79 if (!memcmp(leases[i].chaddr, chaddr, 16)) return &(leases[i]);
85 /* Find the first lease that matches yiaddr, NULL is no match */
86 struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
90 for (i = 0; i < server_config.max_leases; i++)
91 if (leases[i].yiaddr == yiaddr) return &(leases[i]);
97 /* check is an IP is taken, if it is, add it to the lease table */
98 static int check_ip(uint32_t addr)
102 if (arpping(addr, server_config.server, server_config.arp, server_config.interface) == 0) {
104 bb_info_msg("%s belongs to someone, reserving it for %ld seconds",
105 inet_ntoa(temp), server_config.conflict_time);
106 add_lease(blank_chaddr, addr, server_config.conflict_time);
112 /* find an assignable address, it check_expired is true, we check all the expired leases as well.
113 * Maybe this should try expired leases by age... */
114 uint32_t find_address(int check_expired)
117 struct dhcpOfferedAddr *lease = NULL;
119 addr = ntohl(server_config.start); /* addr is in host order here */
120 for (;addr <= ntohl(server_config.end); addr++) {
122 /* ie, 192.168.55.0 */
123 if (!(addr & 0xFF)) continue;
125 /* ie, 192.168.55.255 */
126 if ((addr & 0xFF) == 0xFF) continue;
128 /* Only do if it isn't an assigned as a static lease */
129 if (!reservedIp(server_config.static_leases, htonl(addr))) {
131 /* lease is not taken */
133 lease = find_lease_by_yiaddr(ret);
135 /* no lease or it expired and we are checking for expired leases */
136 if ( (!lease || (check_expired && lease_expired(lease)))
137 && /* and it isn't on the network */ !check_ip(ret)