/* vi: set sw=4 ts=4: */
/*
- * leases.c -- tools to manage DHCP leases
* Russ Dill <Russ.Dill@asu.edu> July 2001
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
*/
-
#include "common.h"
#include "dhcpd.h"
-
/* Find the oldest expired lease, NULL if there are no expired leases */
-static struct dhcpOfferedAddr *oldest_expired_lease(void)
+static struct dyn_lease *oldest_expired_lease(void)
{
- struct dhcpOfferedAddr *oldest = NULL;
- unsigned long oldest_lease = time(0);
+ struct dyn_lease *oldest_lease = NULL;
+ leasetime_t oldest_time = time(NULL);
unsigned i;
-
- for (i = 0; i < server_config.max_leases; i++)
- if (oldest_lease > leases[i].expires) {
- oldest_lease = leases[i].expires;
- oldest = &(leases[i]);
+ /* Unexpired leases have g_leases[i].expires >= current time
+ * and therefore can't ever match */
+ for (i = 0; i < server_config.max_leases; i++) {
+ if (g_leases[i].expires < oldest_time) {
+ oldest_time = g_leases[i].expires;
+ oldest_lease = &g_leases[i];
}
- return oldest;
+ }
+ return oldest_lease;
}
-
-/* clear every lease out that chaddr OR yiaddr matches and is nonzero */
-static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
+/* Clear out all leases with matching nonzero chaddr OR yiaddr.
+ * If chaddr == NULL, this is a conflict lease.
+ */
+static void clear_leases(const uint8_t *chaddr, uint32_t yiaddr)
{
- unsigned i, j;
-
- for (j = 0; j < 16 && !chaddr[j]; j++);
+ unsigned i;
- for (i = 0; i < server_config.max_leases; i++)
- if ((j != 16 && memcmp(leases[i].chaddr, chaddr, 16) != 0)
- || (yiaddr && leases[i].yiaddr == yiaddr)
+ for (i = 0; i < server_config.max_leases; i++) {
+ if ((chaddr && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
+ || (yiaddr && g_leases[i].lease_nip == yiaddr)
) {
- memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
+ memset(&g_leases[i], 0, sizeof(g_leases[i]));
}
+ }
}
-
-/* add a lease into the table, clearing out any old ones */
-struct dhcpOfferedAddr *add_lease(const uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
+/* Add a lease into the table, clearing out any old ones.
+ * If chaddr == NULL, this is a conflict lease.
+ */
+struct dyn_lease* FAST_FUNC add_lease(
+ const uint8_t *chaddr, uint32_t yiaddr,
+ leasetime_t leasetime,
+ const char *hostname, int hostname_len)
{
- struct dhcpOfferedAddr *oldest;
+ struct dyn_lease *oldest;
/* clean out any old ones */
- clear_lease(chaddr, yiaddr);
+ clear_leases(chaddr, yiaddr);
oldest = oldest_expired_lease();
if (oldest) {
- memcpy(oldest->chaddr, chaddr, 16);
- oldest->yiaddr = yiaddr;
- oldest->expires = time(0) + lease;
+ memset(oldest, 0, sizeof(*oldest));
+ if (hostname) {
+ char *p;
+
+ hostname_len++; /* include NUL */
+ if (hostname_len > sizeof(oldest->hostname))
+ hostname_len = sizeof(oldest->hostname);
+ p = safe_strncpy(oldest->hostname, hostname, hostname_len);
+ /* sanitization (s/non-ASCII/^/g) */
+ while (*p) {
+ if (*p < ' ' || *p > 126)
+ *p = '^';
+ p++;
+ }
+ }
+ if (chaddr)
+ memcpy(oldest->lease_mac, chaddr, 6);
+ oldest->lease_nip = yiaddr;
+ oldest->expires = time(NULL) + leasetime;
}
return oldest;
}
-
-/* true if a lease has expired */
-int lease_expired(struct dhcpOfferedAddr *lease)
+/* True if a lease has expired */
+int FAST_FUNC is_expired_lease(struct dyn_lease *lease)
{
- return (lease->expires < (unsigned long) time(0));
+ return (lease->expires < (leasetime_t) time(NULL));
}
-
-/* Find the first lease that matches chaddr, NULL if no match */
-struct dhcpOfferedAddr *find_lease_by_chaddr(const uint8_t *chaddr)
+/* Find the first lease that matches MAC, NULL if no match */
+struct dyn_lease* FAST_FUNC find_lease_by_mac(const uint8_t *mac)
{
unsigned i;
for (i = 0; i < server_config.max_leases; i++)
- if (!memcmp(leases[i].chaddr, chaddr, 16))
- return &(leases[i]);
+ if (memcmp(g_leases[i].lease_mac, mac, 6) == 0)
+ return &g_leases[i];
return NULL;
}
-
-/* Find the first lease that matches yiaddr, NULL is no match */
-struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
+/* Find the first lease that matches IP, NULL is no match */
+struct dyn_lease* FAST_FUNC find_lease_by_nip(uint32_t nip)
{
unsigned i;
for (i = 0; i < server_config.max_leases; i++)
- if (leases[i].yiaddr == yiaddr)
- return &(leases[i]);
+ if (g_leases[i].lease_nip == nip)
+ return &g_leases[i];
return NULL;
}
-
-/* check is an IP is taken, if it is, add it to the lease table */
-static int nobody_responds_to_arp(uint32_t addr)
+/* Check if the IP is taken; if it is, add it to the lease table */
+static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac)
{
- static const uint8_t blank_chaddr[16]; /* 16 zero bytes */
-
struct in_addr temp;
int r;
- r = arpping(addr, server_config.server, server_config.arp, server_config.interface);
+ r = arpping(nip, safe_mac,
+ server_config.server_nip,
+ server_config.server_mac,
+ server_config.interface);
if (r)
return r;
- temp.s_addr = addr;
+ temp.s_addr = nip;
bb_info_msg("%s belongs to someone, reserving it for %u seconds",
inet_ntoa(temp), (unsigned)server_config.conflict_time);
- add_lease(blank_chaddr, addr, server_config.conflict_time);
+ add_lease(NULL, nip, server_config.conflict_time, NULL, 0);
return 0;
}
-
-/* find an assignable address, if check_expired is true, we check all the expired leases as well.
- * Maybe this should try expired leases by age... */
-uint32_t find_address(int check_expired)
+/* Find a new usable (we think) address */
+uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac)
{
- uint32_t addr, ret;
- struct dhcpOfferedAddr *lease = NULL;
-
- addr = server_config.start_ip; /* addr is in host order here */
- for (;addr <= server_config.end_ip; addr++) {
+ uint32_t addr;
+ struct dyn_lease *oldest_lease = NULL;
+
+#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
+ uint32_t stop;
+ unsigned i, hash;
+
+ /* hash hwaddr: use the SDBM hashing algorithm. Seems to give good
+ * dispersal even with similarly-valued "strings".
+ */
+ hash = 0;
+ for (i = 0; i < 6; i++)
+ hash += safe_mac[i] + (hash << 6) + (hash << 16) - hash;
+
+ /* pick a seed based on hwaddr then iterate until we find a free address. */
+ addr = server_config.start_ip
+ + (hash % (1 + server_config.end_ip - server_config.start_ip));
+ stop = addr;
+#else
+ addr = server_config.start_ip;
+#define stop (server_config.end_ip + 1)
+#endif
+ do {
+ uint32_t nip;
+ struct dyn_lease *lease;
/* ie, 192.168.55.0 */
- if (!(addr & 0xFF)) continue;
-
+ if ((addr & 0xff) == 0)
+ goto next_addr;
/* ie, 192.168.55.255 */
- if ((addr & 0xFF) == 0xFF) continue;
-
- /* Only do if it isn't assigned as a static lease */
- ret = htonl(addr);
- if (!reservedIp(server_config.static_leases, ret)) {
- /* lease is not taken */
- lease = find_lease_by_yiaddr(ret);
-
- /* no lease or it expired and we are checking for expired leases */
- if ((!lease || (check_expired && lease_expired(lease)))
- && nobody_responds_to_arp(ret) /* it isn't used on the network */
- ) {
- return ret;
- }
+ if ((addr & 0xff) == 0xff)
+ goto next_addr;
+ nip = htonl(addr);
+ /* skip our own address */
+ if (nip == server_config.server_nip)
+ goto next_addr;
+ /* is this a static lease addr? */
+ if (is_nip_reserved(server_config.static_leases, nip))
+ goto next_addr;
+
+ lease = find_lease_by_nip(nip);
+ if (!lease) {
+//TODO: DHCP servers do not always sit on the same subnet as clients: should *ping*, not arp-ping!
+ if (nobody_responds_to_arp(nip, safe_mac))
+ return nip;
+ } else {
+ if (!oldest_lease || lease->expires < oldest_lease->expires)
+ oldest_lease = lease;
}
+
+ next_addr:
+ addr++;
+#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
+ if (addr > server_config.end_ip)
+ addr = server_config.start_ip;
+#endif
+ } while (addr != stop);
+
+ if (oldest_lease
+ && is_expired_lease(oldest_lease)
+ && nobody_responds_to_arp(oldest_lease->lease_nip, safe_mac)
+ ) {
+ return oldest_lease->lease_nip;
}
+
return 0;
}
projects / oweals / busybox.git / blobdiff