1 files changed, 158 insertions, 0 deletions
diff --git a/networking/udhcp/leases.c b/networking/udhcp/leases.c
new file mode 100644
index 0000000..bb08c3a
--- /dev/null
+++ b/networking/udhcp/leases.c
@@ -0,0 +1,158 @@
+/*
+ * leases.c -- tools to manage DHCP leases
+ * Russ Dill <Russ.Dill@asu.edu> July 2001
+ */
+
+#include <time.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include "dhcpd.h"
+#include "files.h"
+#include "options.h"
+#include "leases.h"
+#include "arpping.h"
+#include "common.h"
+
+#include "static_leases.h"
+
+
+uint8_t blank_chaddr[] = {[0 ... 15] = 0};
+
+/* clear every lease out that chaddr OR yiaddr matches and is nonzero */
+void clear_lease(uint8_t *chaddr, uint32_t yiaddr)
+{
+	unsigned int i, j;
+
+	for (j = 0; j < 16 && !chaddr[j]; j++);
+
+	for (i = 0; i < server_config.max_leases; i++)
+		if ((j != 16 && !memcmp(leases[i].chaddr, chaddr, 16)) ||
+		    (yiaddr && leases[i].yiaddr == yiaddr)) {
+			memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
+		}
+}
+
+
+/* add a lease into the table, clearing out any old ones */
+struct dhcpOfferedAddr *add_lease(uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
+{
+	struct dhcpOfferedAddr *oldest;
+
+	/* clean out any old ones */
+	clear_lease(chaddr, yiaddr);
+
+	oldest = oldest_expired_lease();
+
+	if (oldest) {
+		memcpy(oldest->chaddr, chaddr, 16);
+		oldest->yiaddr = yiaddr;
+		oldest->expires = time(0) + lease;
+	}
+
+	return oldest;
+}
+
+
+/* true if a lease has expired */
+int lease_expired(struct dhcpOfferedAddr *lease)
+{
+	return (lease->expires < (unsigned long) time(0));
+}
+
+
+/* Find the oldest expired lease, NULL if there are no expired leases */
+struct dhcpOfferedAddr *oldest_expired_lease(void)
+{
+	struct dhcpOfferedAddr *oldest = NULL;
+	unsigned long oldest_lease = time(0);
+	unsigned int i;
+
+
+	for (i = 0; i < server_config.max_leases; i++)
+		if (oldest_lease > leases[i].expires) {
+			oldest_lease = leases[i].expires;
+			oldest = &(leases[i]);
+		}
+	return oldest;
+
+}
+
+
+/* Find the first lease that matches chaddr, NULL if no match */
+struct dhcpOfferedAddr *find_lease_by_chaddr(uint8_t *chaddr)
+{
+	unsigned int i;
+
+	for (i = 0; i < server_config.max_leases; i++)
+		if (!memcmp(leases[i].chaddr, chaddr, 16)) return &(leases[i]);
+
+	return NULL;
+}
+
+
+/* Find the first lease that matches yiaddr, NULL is no match */
+struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
+{
+	unsigned int i;
+
+	for (i = 0; i < server_config.max_leases; i++)
+		if (leases[i].yiaddr == yiaddr) return &(leases[i]);
+
+	return NULL;
+}
+
+
+/* check is an IP is taken, if it is, add it to the lease table */
+static int check_ip(uint32_t addr)
+{
+	struct in_addr temp;
+
+	if (arpping(addr, server_config.server, server_config.arp, server_config.interface) == 0) {
+		temp.s_addr = addr;
+		LOG(LOG_INFO, "%s belongs to someone, reserving it for %ld seconds",
+			inet_ntoa(temp), server_config.conflict_time);
+		add_lease(blank_chaddr, addr, server_config.conflict_time);
+		return 1;
+	} else return 0;
+}
+
+
+/* find an assignable address, it 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)
+{
+	uint32_t addr, ret;
+	struct dhcpOfferedAddr *lease = NULL;
+
+	addr = ntohl(server_config.start); /* addr is in host order here */
+	for (;addr <= ntohl(server_config.end); addr++) {
+
+		/* ie, 192.168.55.0 */
+		if (!(addr & 0xFF)) continue;
+
+		/* ie, 192.168.55.255 */
+		if ((addr & 0xFF) == 0xFF) continue;
+
+		/* Only do if it isn't an assigned as a static lease */
+		if(!reservedIp(server_config.static_leases, htonl(addr)))
+		{
+
+		/* lease is not taken */
+		ret = htonl(addr);
+		if ((!(lease = find_lease_by_yiaddr(ret)) ||
+
+		     /* or it expired and we are checking for expired leases */
+		     (check_expired  && lease_expired(lease))) &&
+
+		     /* and it isn't on the network */
+		     !check_ip(ret)) {
+			return ret;
+			break;
+		}
+	}
+	}
+	return 0;
+}