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    Contents of /trunk/mkinitrd-magellan/busybox/networking/udhcp/leases.c

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    Revision 984 - (show annotations) (download)
    Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
    File MIME type: text/plain
    File size: 4356 byte(s) 
    -updated to busybox-1.16.1 and enabled blkid/uuid support in default config
    1 /* vi: set sw=4 ts=4: */
    2 /*
    3 * leases.c -- tools to manage DHCP leases
    4 * Russ Dill <Russ.Dill@asu.edu> July 2001
    5 *
    6 * Licensed under GPLv2, see file LICENSE in this tarball for details.
    7 */
    8
    9 #include "common.h"
    10 #include "dhcpd.h"
    11
    12
    13 /* Find the oldest expired lease, NULL if there are no expired leases */
    14 static struct dyn_lease *oldest_expired_lease(void)
    15 {
    16 struct dyn_lease *oldest_lease = NULL;
    17 leasetime_t oldest_time = time(NULL);
    18 unsigned i;
    19
    20 /* Unexpired leases have g_leases[i].expires >= current time
    21 * and therefore can't ever match */
    22 for (i = 0; i < server_config.max_leases; i++) {
    23 if (g_leases[i].expires < oldest_time) {
    24 oldest_time = g_leases[i].expires;
    25 oldest_lease = &g_leases[i];
    26 }
    27 }
    28 return oldest_lease;
    29 }
    30
    31
    32 /* Clear every lease out that chaddr OR yiaddr matches and is nonzero */
    33 static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
    34 {
    35 unsigned i, j;
    36
    37 for (j = 0; j < 16 && !chaddr[j]; j++)
    38 continue;
    39
    40 for (i = 0; i < server_config.max_leases; i++) {
    41 if ((j != 16 && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
    42 || (yiaddr && g_leases[i].lease_nip == yiaddr)
    43 ) {
    44 memset(&g_leases[i], 0, sizeof(g_leases[i]));
    45 }
    46 }
    47 }
    48
    49
    50 /* Add a lease into the table, clearing out any old ones */
    51 struct dyn_lease* FAST_FUNC add_lease(
    52 const uint8_t *chaddr, uint32_t yiaddr,
    53 leasetime_t leasetime,
    54 const char *hostname, int hostname_len)
    55 {
    56 struct dyn_lease *oldest;
    57
    58 /* clean out any old ones */
    59 clear_lease(chaddr, yiaddr);
    60
    61 oldest = oldest_expired_lease();
    62
    63 if (oldest) {
    64 oldest->hostname[0] = '\0';
    65 if (hostname) {
    66 char *p;
    67 if (hostname_len > sizeof(oldest->hostname))
    68 hostname_len = sizeof(oldest->hostname);
    69 p = safe_strncpy(oldest->hostname, hostname, hostname_len);
    70 /* sanitization (s/non-ASCII/^/g) */
    71 while (*p) {
    72 if (*p < ' ' || *p > 126)
    73 *p = '^';
    74 p++;
    75 }
    76 }
    77 memcpy(oldest->lease_mac, chaddr, 6);
    78 oldest->lease_nip = yiaddr;
    79 oldest->expires = time(NULL) + leasetime;
    80 }
    81
    82 return oldest;
    83 }
    84
    85
    86 /* True if a lease has expired */
    87 int FAST_FUNC is_expired_lease(struct dyn_lease *lease)
    88 {
    89 return (lease->expires < (leasetime_t) time(NULL));
    90 }
    91
    92
    93 /* Find the first lease that matches MAC, NULL if no match */
    94 struct dyn_lease* FAST_FUNC find_lease_by_mac(const uint8_t *mac)
    95 {
    96 unsigned i;
    97
    98 for (i = 0; i < server_config.max_leases; i++)
    99 if (memcmp(g_leases[i].lease_mac, mac, 6) == 0)
    100 return &g_leases[i];
    101
    102 return NULL;
    103 }
    104
    105
    106 /* Find the first lease that matches IP, NULL is no match */
    107 struct dyn_lease* FAST_FUNC find_lease_by_nip(uint32_t nip)
    108 {
    109 unsigned i;
    110
    111 for (i = 0; i < server_config.max_leases; i++)
    112 if (g_leases[i].lease_nip == nip)
    113 return &g_leases[i];
    114
    115 return NULL;
    116 }
    117
    118
    119 /* Check if the IP is taken; if it is, add it to the lease table */
    120 static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac)
    121 {
    122 /* 16 zero bytes */
    123 static const uint8_t blank_chaddr[16] = { 0 };
    124 /* = { 0 } helps gcc to put it in rodata, not bss */
    125
    126 struct in_addr temp;
    127 int r;
    128
    129 r = arpping(nip, safe_mac,
    130 server_config.server_nip,
    131 server_config.server_mac,
    132 server_config.interface);
    133 if (r)
    134 return r;
    135
    136 temp.s_addr = nip;
    137 bb_info_msg("%s belongs to someone, reserving it for %u seconds",
    138 inet_ntoa(temp), (unsigned)server_config.conflict_time);
    139 add_lease(blank_chaddr, nip, server_config.conflict_time, NULL, 0);
    140 return 0;
    141 }
    142
    143
    144 /* Find a new usable (we think) address */
    145 uint32_t FAST_FUNC find_free_or_expired_nip(const uint8_t *safe_mac)
    146 {
    147 uint32_t addr;
    148 struct dyn_lease *oldest_lease = NULL;
    149
    150 addr = server_config.start_ip; /* addr is in host order here */
    151 for (; addr <= server_config.end_ip; addr++) {
    152 uint32_t nip;
    153 struct dyn_lease *lease;
    154
    155 /* ie, 192.168.55.0 */
    156 if ((addr & 0xff) == 0)
    157 continue;
    158 /* ie, 192.168.55.255 */
    159 if ((addr & 0xff) == 0xff)
    160 continue;
    161 nip = htonl(addr);
    162 /* is this a static lease addr? */
    163 if (is_nip_reserved(server_config.static_leases, nip))
    164 continue;
    165
    166 lease = find_lease_by_nip(nip);
    167 if (!lease) {
    168 if (nobody_responds_to_arp(nip, safe_mac))
    169 return nip;
    170 } else {
    171 if (!oldest_lease || lease->expires < oldest_lease->expires)
    172 oldest_lease = lease;
    173 }
    174 }
    175
    176 if (oldest_lease && is_expired_lease(oldest_lease)
    177 && nobody_responds_to_arp(oldest_lease->lease_nip, safe_mac)
    178 ) {
    179 return oldest_lease->lease_nip;
    180 }
    181
    182 return 0;
    183 }