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 /* Find the oldest expired lease, NULL if there are no expired leases */
12 static struct dhcpOfferedAddr *oldest_expired_lease(void)
14 struct dhcpOfferedAddr *oldest = NULL;
15 unsigned long oldest_lease = time(0);
19 for (i = 0; i < server_config.max_leases; i++)
20 if (oldest_lease > leases[i].expires) {
21 oldest_lease = leases[i].expires;
22 oldest = &(leases[i]);
28 /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
29 static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
33 for (j = 0; j < 16 && !chaddr[j]; j++);
35 for (i = 0; i < server_config.max_leases; i++)
36 if ((j != 16 && memcmp(leases[i].chaddr, chaddr, 16) != 0)
37 || (yiaddr && leases[i].yiaddr == yiaddr)
39 memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
44 /* add a lease into the table, clearing out any old ones */
45 struct dhcpOfferedAddr *add_lease(const uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
47 struct dhcpOfferedAddr *oldest;
49 /* clean out any old ones */
50 clear_lease(chaddr, yiaddr);
52 oldest = oldest_expired_lease();
55 memcpy(oldest->chaddr, chaddr, 16);
56 oldest->yiaddr = yiaddr;
57 oldest->expires = time(0) + lease;
64 /* true if a lease has expired */
65 int lease_expired(struct dhcpOfferedAddr *lease)
67 return (lease->expires < (unsigned long) time(0));
71 /* Find the first lease that matches chaddr, NULL if no match */
72 struct dhcpOfferedAddr *find_lease_by_chaddr(const uint8_t *chaddr)
76 for (i = 0; i < server_config.max_leases; i++)
77 if (!memcmp(leases[i].chaddr, chaddr, 16))
84 /* Find the first lease that matches yiaddr, NULL is no match */
85 struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
89 for (i = 0; i < server_config.max_leases; i++)
90 if (leases[i].yiaddr == yiaddr)
97 /* check is an IP is taken, if it is, add it to the lease table */
98 static int nobody_responds_to_arp(uint32_t addr)
100 static const uint8_t blank_chaddr[16]; /* 16 zero bytes */
105 r = arpping(addr, server_config.server, server_config.arp, server_config.interface);
110 bb_info_msg("%s belongs to someone, reserving it for %u seconds",
111 inet_ntoa(temp), (unsigned)server_config.conflict_time);
112 add_lease(blank_chaddr, addr, server_config.conflict_time);
117 /* find an assignable address, if check_expired is true, we check all the expired leases as well.
118 * Maybe this should try expired leases by age... */
119 uint32_t find_address(int check_expired)
122 struct dhcpOfferedAddr *lease = NULL;
124 addr = server_config.start_ip; /* addr is in host order here */
125 for (;addr <= server_config.end_ip; addr++) {
127 /* ie, 192.168.55.0 */
128 if (!(addr & 0xFF)) continue;
130 /* ie, 192.168.55.255 */
131 if ((addr & 0xFF) == 0xFF) continue;
133 /* Only do if it isn't assigned as a static lease */
135 if (!reservedIp(server_config.static_leases, ret)) {
136 /* lease is not taken */
137 lease = find_lease_by_yiaddr(ret);
139 /* no lease or it expired and we are checking for expired leases */
140 if ((!lease || (check_expired && lease_expired(lease)))
141 && nobody_responds_to_arp(ret) /* it isn't used on the network */