1 /* vi: set sw=4 ts=4: */
3 * Russ Dill <Russ.Dill@asu.edu> July 2001
5 * Licensed under GPLv2, see file LICENSE in this source tree.
10 /* Find the oldest expired lease, NULL if there are no expired leases */
11 static struct dyn_lease
*oldest_expired_lease(void)
13 struct dyn_lease
*oldest_lease
= NULL
;
14 leasetime_t oldest_time
= time(NULL
);
17 /* Unexpired leases have g_leases[i].expires >= current time
18 * and therefore can't ever match */
19 for (i
= 0; i
< server_config
.max_leases
; i
++) {
20 if (g_leases
[i
].expires
< oldest_time
) {
21 oldest_time
= g_leases
[i
].expires
;
22 oldest_lease
= &g_leases
[i
];
28 /* Clear out all leases with matching nonzero chaddr OR yiaddr.
29 * If chaddr == NULL, this is a conflict lease.
31 static void clear_leases(const uint8_t *chaddr
, uint32_t yiaddr
)
35 for (i
= 0; i
< server_config
.max_leases
; i
++) {
36 if ((chaddr
&& memcmp(g_leases
[i
].lease_mac
, chaddr
, 6) == 0)
37 || (yiaddr
&& g_leases
[i
].lease_nip
== yiaddr
)
39 memset(&g_leases
[i
], 0, sizeof(g_leases
[i
]));
44 /* Add a lease into the table, clearing out any old ones.
45 * If chaddr == NULL, this is a conflict lease.
47 struct dyn_lease
* FAST_FUNC
add_lease(
48 const uint8_t *chaddr
, uint32_t yiaddr
,
49 leasetime_t leasetime
,
50 const char *hostname
, int hostname_len
)
52 struct dyn_lease
*oldest
;
54 /* clean out any old ones */
55 clear_leases(chaddr
, yiaddr
);
57 oldest
= oldest_expired_lease();
60 memset(oldest
, 0, sizeof(*oldest
));
64 hostname_len
++; /* include NUL */
65 if (hostname_len
> sizeof(oldest
->hostname
))
66 hostname_len
= sizeof(oldest
->hostname
);
67 p
= safe_strncpy(oldest
->hostname
, hostname
, hostname_len
);
68 /* sanitization (s/non-ASCII/^/g) */
70 if (*p
< ' ' || *p
> 126)
76 memcpy(oldest
->lease_mac
, chaddr
, 6);
77 oldest
->lease_nip
= yiaddr
;
78 oldest
->expires
= time(NULL
) + leasetime
;
84 /* True if a lease has expired */
85 int FAST_FUNC
is_expired_lease(struct dyn_lease
*lease
)
87 return (lease
->expires
< (leasetime_t
) time(NULL
));
90 /* Find the first lease that matches MAC, NULL if no match */
91 struct dyn_lease
* FAST_FUNC
find_lease_by_mac(const uint8_t *mac
)
95 for (i
= 0; i
< server_config
.max_leases
; i
++)
96 if (memcmp(g_leases
[i
].lease_mac
, mac
, 6) == 0)
102 /* Find the first lease that matches IP, NULL is no match */
103 struct dyn_lease
* FAST_FUNC
find_lease_by_nip(uint32_t nip
)
107 for (i
= 0; i
< server_config
.max_leases
; i
++)
108 if (g_leases
[i
].lease_nip
== nip
)
114 /* Check if the IP is taken; if it is, add it to the lease table */
115 static int nobody_responds_to_arp(uint32_t nip
, const uint8_t *safe_mac
)
120 r
= arpping(nip
, safe_mac
,
121 server_config
.server_nip
,
122 server_config
.server_mac
,
123 server_config
.interface
);
128 bb_info_msg("%s belongs to someone, reserving it for %u seconds",
129 inet_ntoa(temp
), (unsigned)server_config
.conflict_time
);
130 add_lease(NULL
, nip
, server_config
.conflict_time
, NULL
, 0);
134 /* Find a new usable (we think) address */
135 uint32_t FAST_FUNC
find_free_or_expired_nip(const uint8_t *safe_mac
)
138 struct dyn_lease
*oldest_lease
= NULL
;
140 #if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
144 /* hash hwaddr: use the SDBM hashing algorithm. Seems to give good
145 * dispersal even with similarly-valued "strings".
148 for (i
= 0; i
< 6; i
++)
149 hash
+= safe_mac
[i
] + (hash
<< 6) + (hash
<< 16) - hash
;
151 /* pick a seed based on hwaddr then iterate until we find a free address. */
152 addr
= server_config
.start_ip
153 + (hash
% (1 + server_config
.end_ip
- server_config
.start_ip
));
156 addr
= server_config
.start_ip
;
157 #define stop (server_config.end_ip + 1)
161 struct dyn_lease
*lease
;
163 /* ie, 192.168.55.0 */
164 if ((addr
& 0xff) == 0)
166 /* ie, 192.168.55.255 */
167 if ((addr
& 0xff) == 0xff)
170 /* skip our own address */
171 if (nip
== server_config
.server_nip
)
173 /* is this a static lease addr? */
174 if (is_nip_reserved(server_config
.static_leases
, nip
))
177 lease
= find_lease_by_nip(nip
);
179 //TODO: DHCP servers do not always sit on the same subnet as clients: should *ping*, not arp-ping!
180 if (nobody_responds_to_arp(nip
, safe_mac
))
183 if (!oldest_lease
|| lease
->expires
< oldest_lease
->expires
)
184 oldest_lease
= lease
;
189 #if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
190 if (addr
> server_config
.end_ip
)
191 addr
= server_config
.start_ip
;
193 } while (addr
!= stop
);
196 && is_expired_lease(oldest_lease
)
197 && nobody_responds_to_arp(oldest_lease
->lease_nip
, safe_mac
)
199 return oldest_lease
->lease_nip
;