[821] | 1 | /*
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| 2 | * leases.c -- tools to manage DHCP leases
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| 3 | * Russ Dill <Russ.Dill@asu.edu> July 2001
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| 4 | */
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| 5 |
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| 6 | #include <time.h>
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| 7 | #include <string.h>
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| 8 | #include <sys/socket.h>
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| 9 | #include <netinet/in.h>
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| 10 | #include <arpa/inet.h>
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| 11 |
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| 12 | #include "dhcpd.h"
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| 13 | #include "files.h"
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| 14 | #include "options.h"
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| 15 | #include "leases.h"
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| 16 | #include "arpping.h"
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| 17 | #include "common.h"
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| 18 |
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| 19 | #include "static_leases.h"
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| 20 |
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| 21 |
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| 22 | uint8_t blank_chaddr[] = {[0 ... 15] = 0};
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| 23 |
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| 24 | /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
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| 25 | void clear_lease(uint8_t *chaddr, uint32_t yiaddr)
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| 26 | {
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| 27 | unsigned int i, j;
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| 28 |
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| 29 | for (j = 0; j < 16 && !chaddr[j]; j++);
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| 30 |
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| 31 | for (i = 0; i < server_config.max_leases; i++)
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| 32 | if ((j != 16 && !memcmp(leases[i].chaddr, chaddr, 16)) ||
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| 33 | (yiaddr && leases[i].yiaddr == yiaddr)) {
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| 34 | memset(&(leases[i]), 0, sizeof(struct dhcpOfferedAddr));
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| 35 | }
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| 36 | }
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| 37 |
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| 38 |
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| 39 | /* add a lease into the table, clearing out any old ones */
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| 40 | struct dhcpOfferedAddr *add_lease(uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
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| 41 | {
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| 42 | struct dhcpOfferedAddr *oldest;
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| 43 |
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| 44 | /* clean out any old ones */
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| 45 | clear_lease(chaddr, yiaddr);
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| 46 |
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| 47 | oldest = oldest_expired_lease();
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| 48 |
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| 49 | if (oldest) {
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| 50 | memcpy(oldest->chaddr, chaddr, 16);
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| 51 | oldest->yiaddr = yiaddr;
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| 52 | oldest->expires = time(0) + lease;
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| 53 | }
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| 54 |
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| 55 | return oldest;
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| 56 | }
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| 57 |
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| 58 |
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| 59 | /* true if a lease has expired */
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| 60 | int lease_expired(struct dhcpOfferedAddr *lease)
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| 61 | {
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| 62 | return (lease->expires < (unsigned long) time(0));
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| 63 | }
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| 64 |
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| 65 |
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| 66 | /* Find the oldest expired lease, NULL if there are no expired leases */
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| 67 | struct dhcpOfferedAddr *oldest_expired_lease(void)
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| 68 | {
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| 69 | struct dhcpOfferedAddr *oldest = NULL;
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| 70 | unsigned long oldest_lease = time(0);
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| 71 | unsigned int i;
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| 72 |
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| 73 |
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| 74 | for (i = 0; i < server_config.max_leases; i++)
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| 75 | if (oldest_lease > leases[i].expires) {
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| 76 | oldest_lease = leases[i].expires;
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| 77 | oldest = &(leases[i]);
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| 78 | }
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| 79 | return oldest;
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| 80 |
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| 81 | }
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| 82 |
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| 83 |
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| 84 | /* Find the first lease that matches chaddr, NULL if no match */
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| 85 | struct dhcpOfferedAddr *find_lease_by_chaddr(uint8_t *chaddr)
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| 86 | {
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| 87 | unsigned int i;
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| 88 |
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| 89 | for (i = 0; i < server_config.max_leases; i++)
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| 90 | if (!memcmp(leases[i].chaddr, chaddr, 16)) return &(leases[i]);
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| 91 |
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| 92 | return NULL;
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| 93 | }
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| 94 |
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| 95 |
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| 96 | /* Find the first lease that matches yiaddr, NULL is no match */
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| 97 | struct dhcpOfferedAddr *find_lease_by_yiaddr(uint32_t yiaddr)
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| 98 | {
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| 99 | unsigned int i;
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| 100 |
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| 101 | for (i = 0; i < server_config.max_leases; i++)
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| 102 | if (leases[i].yiaddr == yiaddr) return &(leases[i]);
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| 103 |
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| 104 | return NULL;
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| 105 | }
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| 106 |
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| 107 |
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| 108 | /* check is an IP is taken, if it is, add it to the lease table */
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| 109 | static int check_ip(uint32_t addr)
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| 110 | {
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| 111 | struct in_addr temp;
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| 112 |
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| 113 | if (arpping(addr, server_config.server, server_config.arp, server_config.interface) == 0) {
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| 114 | temp.s_addr = addr;
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| 115 | LOG(LOG_INFO, "%s belongs to someone, reserving it for %ld seconds",
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| 116 | inet_ntoa(temp), server_config.conflict_time);
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| 117 | add_lease(blank_chaddr, addr, server_config.conflict_time);
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| 118 | return 1;
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| 119 | } else return 0;
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| 120 | }
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| 121 |
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| 122 |
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| 123 | /* find an assignable address, it check_expired is true, we check all the expired leases as well.
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| 124 | * Maybe this should try expired leases by age... */
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| 125 | uint32_t find_address(int check_expired)
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| 126 | {
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| 127 | uint32_t addr, ret;
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| 128 | struct dhcpOfferedAddr *lease = NULL;
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| 129 |
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| 130 | addr = ntohl(server_config.start); /* addr is in host order here */
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| 131 | for (;addr <= ntohl(server_config.end); addr++) {
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| 132 |
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| 133 | /* ie, 192.168.55.0 */
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| 134 | if (!(addr & 0xFF)) continue;
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| 135 |
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| 136 | /* ie, 192.168.55.255 */
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| 137 | if ((addr & 0xFF) == 0xFF) continue;
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| 138 |
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| 139 | /* Only do if it isn't an assigned as a static lease */
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| 140 | if(!reservedIp(server_config.static_leases, htonl(addr)))
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| 141 | {
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| 142 |
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| 143 | /* lease is not taken */
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| 144 | ret = htonl(addr);
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| 145 | if ((!(lease = find_lease_by_yiaddr(ret)) ||
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| 146 |
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| 147 | /* or it expired and we are checking for expired leases */
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| 148 | (check_expired && lease_expired(lease))) &&
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| 149 |
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| 150 | /* and it isn't on the network */
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| 151 | !check_ip(ret)) {
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| 152 | return ret;
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| 153 | break;
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| 154 | }
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| 155 | }
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| 156 | }
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| 157 | return 0;
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| 158 | }
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