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

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    Revision 816 - (hide 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 niro 532 /* 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 niro 816 /* 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 niro 532
    19 niro 816 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 niro 532 /* clear every lease out that chaddr OR yiaddr matches and is nonzero */
    29 niro 816 static void clear_lease(const uint8_t *chaddr, uint32_t yiaddr)
    30 niro 532 {
    31 niro 816 unsigned i, j;
    32 niro 532
    33 niro 816 for (j = 0; j < 16 && !chaddr[j]; j++)
    34     continue;
    35 niro 532
    36     for (i = 0; i < server_config.max_leases; i++)
    37 niro 816 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 niro 532 }
    42     }
    43    
    44    
    45     /* add a lease into the table, clearing out any old ones */
    46 niro 816 struct dhcpOfferedAddr* FAST_FUNC add_lease(const uint8_t *chaddr, uint32_t yiaddr, unsigned long lease)
    47 niro 532 {
    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 niro 816 int FAST_FUNC lease_expired(struct dhcpOfferedAddr *lease)
    67 niro 532 {
    68     return (lease->expires < (unsigned long) time(0));
    69     }
    70    
    71    
    72     /* Find the first lease that matches chaddr, NULL if no match */
    73 niro 816 struct dhcpOfferedAddr* FAST_FUNC find_lease_by_chaddr(const uint8_t *chaddr)
    74 niro 532 {
    75 niro 816 unsigned i;
    76 niro 532
    77     for (i = 0; i < server_config.max_leases; i++)
    78 niro 816 if (!memcmp(leases[i].chaddr, chaddr, 16))
    79     return &(leases[i]);
    80 niro 532
    81     return NULL;
    82     }
    83    
    84    
    85     /* Find the first lease that matches yiaddr, NULL is no match */
    86 niro 816 struct dhcpOfferedAddr* FAST_FUNC find_lease_by_yiaddr(uint32_t yiaddr)
    87 niro 532 {
    88 niro 816 unsigned i;
    89 niro 532
    90     for (i = 0; i < server_config.max_leases; i++)
    91 niro 816 if (leases[i].yiaddr == yiaddr)
    92     return &(leases[i]);
    93 niro 532
    94     return NULL;
    95     }
    96    
    97    
    98     /* check is an IP is taken, if it is, add it to the lease table */
    99 niro 816 static int nobody_responds_to_arp(uint32_t addr)
    100 niro 532 {
    101 niro 816 /* 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 niro 532 struct in_addr temp;
    106 niro 816 int r;
    107 niro 532
    108 niro 816 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 niro 532 }
    118    
    119    
    120 niro 816 /* find an assignable address, if check_expired is true, we check all the expired leases as well.
    121 niro 532 * Maybe this should try expired leases by age... */
    122 niro 816 uint32_t FAST_FUNC find_address(int check_expired)
    123 niro 532 {
    124     uint32_t addr, ret;
    125     struct dhcpOfferedAddr *lease = NULL;
    126    
    127 niro 816 addr = server_config.start_ip; /* addr is in host order here */
    128     for (; addr <= server_config.end_ip; addr++) {
    129 niro 532 /* ie, 192.168.55.0 */
    130 niro 816 if (!(addr & 0xFF))
    131     continue;
    132 niro 532 /* ie, 192.168.55.255 */
    133 niro 816 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 niro 532 /* 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 niro 816 if ((!lease || (check_expired && lease_expired(lease)))
    142     && nobody_responds_to_arp(ret) /* it isn't used on the network */
    143 niro 532 ) {
    144     return ret;
    145     }
    146     }
    147     }
    148     return 0;
    149     }