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 // TODO: use monotonic_sec()
16 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++)
36 for (i = 0; i < server_config.max_leases; i++)
37 if ((j != 16 && memcmp(leases[i].chaddr, chaddr, 16) == 0)
38 || (yiaddr && leases[i].yiaddr == yiaddr)
40 memset(&(leases[i]), 0, sizeof(leases[i]));
45 /* add a lease into the table, clearing out any old ones */
46 struct dhcpOfferedAddr* FAST_FUNC add_lease(const uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
48 struct dhcpOfferedAddr *oldest;
50 /* clean out any old ones */
51 clear_lease(chaddr, yiaddr);
53 oldest = oldest_expired_lease();
56 memcpy(oldest->chaddr, chaddr, 16);
57 oldest->yiaddr = yiaddr;
58 oldest->expires = time(0) + lease;
65 /* true if a lease has expired */
66 int FAST_FUNC lease_expired(struct dhcpOfferedAddr *lease)
68 return (lease->expires < (unsigned long) time(0));
72 /* Find the first lease that matches chaddr, NULL if no match */
73 struct dhcpOfferedAddr* FAST_FUNC find_lease_by_chaddr(const uint8_t *chaddr)
77 for (i = 0; i < server_config.max_leases; i++)
78 if (!memcmp(leases[i].chaddr, chaddr, 16))
85 /* Find the first lease that matches yiaddr, NULL is no match */
86 struct dhcpOfferedAddr* FAST_FUNC find_lease_by_yiaddr(uint32_t yiaddr)
90 for (i = 0; i < server_config.max_leases; i++)
91 if (leases[i].yiaddr == yiaddr)
98 /* check is an IP is taken, if it is, add it to the lease table */
99 static int nobody_responds_to_arp(uint32_t addr)
102 static const uint8_t blank_chaddr[16] = { 0 };
103 /* = { 0 } helps gcc to put it in rodata, not bss */
108 r = arpping(addr, server_config.server, server_config.arp, server_config.interface);
113 bb_info_msg("%s belongs to someone, reserving it for %u seconds",
114 inet_ntoa(temp), (unsigned)server_config.conflict_time);
115 add_lease(blank_chaddr, addr, server_config.conflict_time);
120 /* find an assignable address, if check_expired is true, we check all the expired leases as well.
121 * Maybe this should try expired leases by age... */
122 uint32_t FAST_FUNC find_address(int check_expired)
125 struct dhcpOfferedAddr *lease = NULL;
127 addr = server_config.start_ip; /* addr is in host order here */
128 for (; addr <= server_config.end_ip; addr++) {
129 /* ie, 192.168.55.0 */
132 /* ie, 192.168.55.255 */
133 if ((addr & 0xFF) == 0xFF)
135 /* Only do if it isn't assigned as a static lease */
137 if (!reservedIp(server_config.static_leases, ret)) {
138 /* lease is not taken */
139 lease = find_lease_by_yiaddr(ret);
140 /* no lease or it expired and we are checking for expired leases */
141 if ((!lease || (check_expired && lease_expired(lease)))
142 && nobody_responds_to_arp(ret) /* it isn't used on the network */