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

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    Revision 816 - (show annotations) (download)
    Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
    File MIME type: text/plain
    File size: 3733 byte(s) 
    -updated to busybox-1.13.4
    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
    7 #include "common.h"
    8 #include "dhcpd.h"
    9
    10
    11 /* Find the oldest expired lease, NULL if there are no expired leases */
    12 static struct dhcpOfferedAddr *oldest_expired_lease(void)
    13 {
    14 struct dhcpOfferedAddr *oldest = NULL;
    15 // TODO: use monotonic_sec()
    16 unsigned long oldest_lease = time(0);
    17 unsigned i;
    18
    19 for (i = 0; i < server_config.max_leases; i++)
    20 if (oldest_lease > leases[i].expires) {
    21 oldest_lease = leases[i].expires;
    22 oldest = &(leases[i]);
    23 }
    24 return oldest;
    25 }
    26
    27
    28 /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
    29 static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
    30 {
    31 unsigned i, j;
    32
    33 for (j = 0; j < 16 && !chaddr[j]; j++)
    34 continue;
    35
    36 for (i = 0; i < server_config.max_leases; i++)
    37 if ((j != 16 && memcmp(leases[i].chaddr, chaddr, 16) == 0)
    38 || (yiaddr && leases[i].yiaddr == yiaddr)
    39 ) {
    40 memset(&(leases[i]), 0, sizeof(leases[i]));
    41 }
    42 }
    43
    44
    45 /* add a lease into the table, clearing out any old ones */
    46 struct dhcpOfferedAddr* FAST_FUNC add_lease(const uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
    47 {
    48 struct dhcpOfferedAddr *oldest;
    49
    50 /* clean out any old ones */
    51 clear_lease(chaddr, yiaddr);
    52
    53 oldest = oldest_expired_lease();
    54
    55 if (oldest) {
    56 memcpy(oldest->chaddr, chaddr, 16);
    57 oldest->yiaddr = yiaddr;
    58 oldest->expires = time(0) + lease;
    59 }
    60
    61 return oldest;
    62 }
    63
    64
    65 /* true if a lease has expired */
    66 int FAST_FUNC lease_expired(struct dhcpOfferedAddr *lease)
    67 {
    68 return (lease->expires < (unsigned long) time(0));
    69 }
    70
    71
    72 /* Find the first lease that matches chaddr, NULL if no match */
    73 struct dhcpOfferedAddr* FAST_FUNC find_lease_by_chaddr(const uint8_t *chaddr)
    74 {
    75 unsigned i;
    76
    77 for (i = 0; i < server_config.max_leases; i++)
    78 if (!memcmp(leases[i].chaddr, chaddr, 16))
    79 return &(leases[i]);
    80
    81 return NULL;
    82 }
    83
    84
    85 /* Find the first lease that matches yiaddr, NULL is no match */
    86 struct dhcpOfferedAddr* FAST_FUNC find_lease_by_yiaddr(uint32_t yiaddr)
    87 {
    88 unsigned i;
    89
    90 for (i = 0; i < server_config.max_leases; i++)
    91 if (leases[i].yiaddr == yiaddr)
    92 return &(leases[i]);
    93
    94 return NULL;
    95 }
    96
    97
    98 /* check is an IP is taken, if it is, add it to the lease table */
    99 static int nobody_responds_to_arp(uint32_t addr)
    100 {
    101 /* 16 zero bytes */
    102 static const uint8_t blank_chaddr[16] = { 0 };
    103 /* = { 0 } helps gcc to put it in rodata, not bss */
    104
    105 struct in_addr temp;
    106 int r;
    107
    108 r = arpping(addr, server_config.server, server_config.arp, server_config.interface);
    109 if (r)
    110 return r;
    111
    112 temp.s_addr = addr;
    113 bb_info_msg("%s belongs to someone, reserving it for %u seconds",
    114 inet_ntoa(temp), (unsigned)server_config.conflict_time);
    115 add_lease(blank_chaddr, addr, server_config.conflict_time);
    116 return 0;
    117 }
    118
    119
    120 /* find an assignable address, if check_expired is true, we check all the expired leases as well.
    121 * Maybe this should try expired leases by age... */
    122 uint32_t FAST_FUNC find_address(int check_expired)
    123 {
    124 uint32_t addr, ret;
    125 struct dhcpOfferedAddr *lease = NULL;
    126
    127 addr = server_config.start_ip; /* addr is in host order here */
    128 for (; addr <= server_config.end_ip; addr++) {
    129 /* ie, 192.168.55.0 */
    130 if (!(addr & 0xFF))
    131 continue;
    132 /* ie, 192.168.55.255 */
    133 if ((addr & 0xFF) == 0xFF)
    134 continue;
    135 /* Only do if it isn't assigned as a static lease */
    136 ret = htonl(addr);
    137 if (!reservedIp(server_config.static_leases, ret)) {
    138 /* lease is not taken */
    139 lease = find_lease_by_yiaddr(ret);
    140 /* no lease or it expired and we are checking for expired leases */
    141 if ((!lease || (check_expired && lease_expired(lease)))
    142 && nobody_responds_to_arp(ret) /* it isn't used on the network */
    143 ) {
    144 return ret;
    145 }
    146 }
    147 }
    148 return 0;
    149 }