[1765] | 1 | /* vi: set sw=4 ts=4: */
|
---|
[821] | 2 | /*
|
---|
| 3 | * Russ Dill <Russ.Dill@asu.edu> July 2001
|
---|
[2725] | 4 | *
|
---|
| 5 | * Licensed under GPLv2, see file LICENSE in this source tree.
|
---|
[821] | 6 | */
|
---|
[1765] | 7 | #include "common.h"
|
---|
[821] | 8 | #include "dhcpd.h"
|
---|
| 9 |
|
---|
[1765] | 10 | /* Find the oldest expired lease, NULL if there are no expired leases */
|
---|
[2725] | 11 | static struct dyn_lease *oldest_expired_lease(void)
|
---|
[1765] | 12 | {
|
---|
[2725] | 13 | struct dyn_lease *oldest_lease = NULL;
|
---|
| 14 | leasetime_t oldest_time = time(NULL);
|
---|
[1765] | 15 | unsigned i;
|
---|
[821] | 16 |
|
---|
[2725] | 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++) {
|
---|
[3621] | 20 | if (g_leases[i].expires == 0 /* empty entry */
|
---|
| 21 | || g_leases[i].expires < oldest_time
|
---|
| 22 | ) {
|
---|
[2725] | 23 | oldest_time = g_leases[i].expires;
|
---|
| 24 | oldest_lease = &g_leases[i];
|
---|
[1765] | 25 | }
|
---|
[2725] | 26 | }
|
---|
| 27 | return oldest_lease;
|
---|
[1765] | 28 | }
|
---|
[821] | 29 |
|
---|
[2725] | 30 | /* Clear out all leases with matching nonzero chaddr OR yiaddr.
|
---|
| 31 | * If chaddr == NULL, this is a conflict lease.
|
---|
| 32 | */
|
---|
| 33 | static void clear_leases(const uint8_t *chaddr, uint32_t yiaddr)
|
---|
[821] | 34 | {
|
---|
[2725] | 35 | unsigned i;
|
---|
[821] | 36 |
|
---|
[2725] | 37 | for (i = 0; i < server_config.max_leases; i++) {
|
---|
| 38 | if ((chaddr && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
|
---|
| 39 | || (yiaddr && g_leases[i].lease_nip == yiaddr)
|
---|
[1765] | 40 | ) {
|
---|
[2725] | 41 | memset(&g_leases[i], 0, sizeof(g_leases[i]));
|
---|
[821] | 42 | }
|
---|
[2725] | 43 | }
|
---|
[821] | 44 | }
|
---|
| 45 |
|
---|
[2725] | 46 | /* Add a lease into the table, clearing out any old ones.
|
---|
| 47 | * If chaddr == NULL, this is a conflict lease.
|
---|
| 48 | */
|
---|
| 49 | struct dyn_lease* FAST_FUNC add_lease(
|
---|
| 50 | const uint8_t *chaddr, uint32_t yiaddr,
|
---|
| 51 | leasetime_t leasetime,
|
---|
| 52 | const char *hostname, int hostname_len)
|
---|
[821] | 53 | {
|
---|
[2725] | 54 | struct dyn_lease *oldest;
|
---|
[821] | 55 |
|
---|
| 56 | /* clean out any old ones */
|
---|
[2725] | 57 | clear_leases(chaddr, yiaddr);
|
---|
[821] | 58 |
|
---|
| 59 | oldest = oldest_expired_lease();
|
---|
| 60 |
|
---|
| 61 | if (oldest) {
|
---|
[2725] | 62 | memset(oldest, 0, sizeof(*oldest));
|
---|
| 63 | if (hostname) {
|
---|
| 64 | char *p;
|
---|
| 65 |
|
---|
| 66 | hostname_len++; /* include NUL */
|
---|
| 67 | if (hostname_len > sizeof(oldest->hostname))
|
---|
| 68 | hostname_len = sizeof(oldest->hostname);
|
---|
| 69 | p = safe_strncpy(oldest->hostname, hostname, hostname_len);
|
---|
[3621] | 70 | /*
|
---|
| 71 | * Sanitization (s/bad_char/./g).
|
---|
| 72 | * The intent is not to allow only "DNS-valid" hostnames,
|
---|
| 73 | * but merely make dumpleases output safe for shells to use.
|
---|
| 74 | * We accept "0-9A-Za-z._-", all other chars turn to dots.
|
---|
| 75 | */
|
---|
[2725] | 76 | while (*p) {
|
---|
[3621] | 77 | if (!isalnum(*p) && *p != '-' && *p != '_')
|
---|
| 78 | *p = '.';
|
---|
[2725] | 79 | p++;
|
---|
| 80 | }
|
---|
| 81 | }
|
---|
| 82 | if (chaddr)
|
---|
| 83 | memcpy(oldest->lease_mac, chaddr, 6);
|
---|
| 84 | oldest->lease_nip = yiaddr;
|
---|
| 85 | oldest->expires = time(NULL) + leasetime;
|
---|
[821] | 86 | }
|
---|
| 87 |
|
---|
| 88 | return oldest;
|
---|
| 89 | }
|
---|
| 90 |
|
---|
[2725] | 91 | /* True if a lease has expired */
|
---|
| 92 | int FAST_FUNC is_expired_lease(struct dyn_lease *lease)
|
---|
[821] | 93 | {
|
---|
[2725] | 94 | return (lease->expires < (leasetime_t) time(NULL));
|
---|
[821] | 95 | }
|
---|
| 96 |
|
---|
[2725] | 97 | /* Find the first lease that matches MAC, NULL if no match */
|
---|
| 98 | struct dyn_lease* FAST_FUNC find_lease_by_mac(const uint8_t *mac)
|
---|
[821] | 99 | {
|
---|
[1765] | 100 | unsigned i;
|
---|
[821] | 101 |
|
---|
| 102 | for (i = 0; i < server_config.max_leases; i++)
|
---|
[2725] | 103 | if (memcmp(g_leases[i].lease_mac, mac, 6) == 0)
|
---|
| 104 | return &g_leases[i];
|
---|
[821] | 105 |
|
---|
| 106 | return NULL;
|
---|
| 107 | }
|
---|
| 108 |
|
---|
[2725] | 109 | /* Find the first lease that matches IP, NULL is no match */
|
---|
| 110 | struct dyn_lease* FAST_FUNC find_lease_by_nip(uint32_t nip)
|
---|
[821] | 111 | {
|
---|
[1765] | 112 | unsigned i;
|
---|
[821] | 113 |
|
---|
| 114 | for (i = 0; i < server_config.max_leases; i++)
|
---|
[2725] | 115 | if (g_leases[i].lease_nip == nip)
|
---|
| 116 | return &g_leases[i];
|
---|
[821] | 117 |
|
---|
| 118 | return NULL;
|
---|
| 119 | }
|
---|
| 120 |
|
---|
[2725] | 121 | /* Check if the IP is taken; if it is, add it to the lease table */
|
---|
[3621] | 122 | static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac, unsigned arpping_ms)
|
---|
[821] | 123 | {
|
---|
| 124 | struct in_addr temp;
|
---|
[1765] | 125 | int r;
|
---|
[821] | 126 |
|
---|
[2725] | 127 | r = arpping(nip, safe_mac,
|
---|
| 128 | server_config.server_nip,
|
---|
| 129 | server_config.server_mac,
|
---|
[3621] | 130 | server_config.interface,
|
---|
| 131 | arpping_ms);
|
---|
[1765] | 132 | if (r)
|
---|
| 133 | return r;
|
---|
| 134 |
|
---|
[2725] | 135 | temp.s_addr = nip;
|
---|
[3621] | 136 | bb_error_msg("%s belongs to someone, reserving it for %u seconds",
|
---|
[1765] | 137 | inet_ntoa(temp), (unsigned)server_config.conflict_time);
|
---|
[2725] | 138 | add_lease(NULL, nip, server_config.conflict_time, NULL, 0);
|
---|
[1765] | 139 | return 0;
|
---|
[821] | 140 | }
|
---|
| 141 |
|
---|
[2725] | 142 | /* Find a new usable (we think) address */
|
---|
[3621] | 143 | uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac, unsigned arpping_ms)
|
---|
[821] | 144 | {
|
---|
[2725] | 145 | uint32_t addr;
|
---|
| 146 | struct dyn_lease *oldest_lease = NULL;
|
---|
[821] | 147 |
|
---|
[3232] | 148 | #if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
|
---|
| 149 | uint32_t stop;
|
---|
| 150 | unsigned i, hash;
|
---|
| 151 |
|
---|
| 152 | /* hash hwaddr: use the SDBM hashing algorithm. Seems to give good
|
---|
| 153 | * dispersal even with similarly-valued "strings".
|
---|
| 154 | */
|
---|
| 155 | hash = 0;
|
---|
| 156 | for (i = 0; i < 6; i++)
|
---|
| 157 | hash += safe_mac[i] + (hash << 6) + (hash << 16) - hash;
|
---|
| 158 |
|
---|
| 159 | /* pick a seed based on hwaddr then iterate until we find a free address. */
|
---|
| 160 | addr = server_config.start_ip
|
---|
| 161 | + (hash % (1 + server_config.end_ip - server_config.start_ip));
|
---|
| 162 | stop = addr;
|
---|
| 163 | #else
|
---|
| 164 | addr = server_config.start_ip;
|
---|
| 165 | #define stop (server_config.end_ip + 1)
|
---|
| 166 | #endif
|
---|
| 167 | do {
|
---|
[2725] | 168 | uint32_t nip;
|
---|
| 169 | struct dyn_lease *lease;
|
---|
| 170 |
|
---|
[821] | 171 | /* ie, 192.168.55.0 */
|
---|
[2725] | 172 | if ((addr & 0xff) == 0)
|
---|
[3232] | 173 | goto next_addr;
|
---|
[821] | 174 | /* ie, 192.168.55.255 */
|
---|
[2725] | 175 | if ((addr & 0xff) == 0xff)
|
---|
[3232] | 176 | goto next_addr;
|
---|
[2725] | 177 | nip = htonl(addr);
|
---|
[3232] | 178 | /* skip our own address */
|
---|
| 179 | if (nip == server_config.server_nip)
|
---|
| 180 | goto next_addr;
|
---|
[2725] | 181 | /* is this a static lease addr? */
|
---|
| 182 | if (is_nip_reserved(server_config.static_leases, nip))
|
---|
[3232] | 183 | goto next_addr;
|
---|
[2725] | 184 |
|
---|
| 185 | lease = find_lease_by_nip(nip);
|
---|
| 186 | if (!lease) {
|
---|
| 187 | //TODO: DHCP servers do not always sit on the same subnet as clients: should *ping*, not arp-ping!
|
---|
[3621] | 188 | if (nobody_responds_to_arp(nip, safe_mac, arpping_ms))
|
---|
[2725] | 189 | return nip;
|
---|
| 190 | } else {
|
---|
| 191 | if (!oldest_lease || lease->expires < oldest_lease->expires)
|
---|
| 192 | oldest_lease = lease;
|
---|
[821] | 193 | }
|
---|
[2725] | 194 |
|
---|
[3232] | 195 | next_addr:
|
---|
| 196 | addr++;
|
---|
| 197 | #if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
|
---|
| 198 | if (addr > server_config.end_ip)
|
---|
| 199 | addr = server_config.start_ip;
|
---|
| 200 | #endif
|
---|
| 201 | } while (addr != stop);
|
---|
| 202 |
|
---|
[2725] | 203 | if (oldest_lease
|
---|
| 204 | && is_expired_lease(oldest_lease)
|
---|
[3621] | 205 | && nobody_responds_to_arp(oldest_lease->lease_nip, safe_mac, arpping_ms)
|
---|
[2725] | 206 | ) {
|
---|
| 207 | return oldest_lease->lease_nip;
|
---|
| 208 | }
|
---|
| 209 |
|
---|
[821] | 210 | return 0;
|
---|
| 211 | }
|
---|