networking/udhcp/files.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * files.c -- DHCP server file manipulation *
   4  * Rewrite by 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 <netinet/ether.h>
  10
  11 #include "common.h"
  12 #include "dhcpd.h"
  13
  14 #if BB_LITTLE_ENDIAN
  15 static inline uint64_t hton64(uint64_t v)
  16 {
  17         return (((uint64_t)htonl(v)) << 32) | htonl(v >> 32);
  18 }
  19 #else
  20 #define hton64(v) (v)
  21 #endif
  22 #define ntoh64(v) hton64(v)
  23
  24 /* on these functions, make sure your datatype matches */
  25 static int FAST_FUNC read_str(const char *line, void *arg)
  26 {
  27         char **dest = arg;
  28
  29         free(*dest);
  30         *dest = xstrdup(line);
  31         return 1;
  32 }
  33
  34 static int FAST_FUNC read_u32(const char *line, void *arg)
  35 {
  36         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  37         return errno == 0;
  38 }
  39
  40 static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
  41 {
  42         char *line;
  43         char *mac_string;
  44         char *ip_string;
  45         struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
  46         uint32_t nip;
  47
  48         /* Read mac */
  49         line = (char *) const_line;
  50         mac_string = strtok_r(line, " \t", &line);
  51         if (!mac_string || !ether_aton_r(mac_string, &mac_bytes))
  52                 return 0;
  53
  54         /* Read ip */
  55         ip_string = strtok_r(NULL, " \t", &line);
  56         if (!ip_string || !udhcp_str2nip(ip_string, &nip))
  57                 return 0;
  58
  59         add_static_lease(arg, (uint8_t*) &mac_bytes, nip);
  60
  61         log_static_leases(arg);
  62
  63         return 1;
  64 }
  65
  66
  67 struct config_keyword {
  68         const char *keyword;
  69         int (*handler)(const char *line, void *var) FAST_FUNC;
  70         void *var;
  71         const char *def;
  72 };
  73
  74 static const struct config_keyword keywords[] = {
  75         /* keyword       handler   variable address               default */
  76         {"start",        udhcp_str2nip, &(server_config.start_ip),     "192.168.0.20"},
  77         {"end",          udhcp_str2nip, &(server_config.end_ip),       "192.168.0.254"},
  78         {"interface",    read_str, &(server_config.interface),    "eth0"},
  79         /* Avoid "max_leases value not sane" warning by setting default
  80          * to default_end_ip - default_start_ip + 1: */
  81         {"max_leases",   read_u32, &(server_config.max_leases),   "235"},
  82         {"auto_time",    read_u32, &(server_config.auto_time),    "7200"},
  83         {"decline_time", read_u32, &(server_config.decline_time), "3600"},
  84         {"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
  85         {"offer_time",   read_u32, &(server_config.offer_time),   "60"},
  86         {"min_lease",    read_u32, &(server_config.min_lease_sec),"60"},
  87         {"lease_file",   read_str, &(server_config.lease_file),   LEASES_FILE},
  88         {"pidfile",      read_str, &(server_config.pidfile),      "/var/run/udhcpd.pid"},
  89         {"siaddr",       udhcp_str2nip, &(server_config.siaddr_nip),   "0.0.0.0"},
  90         /* keywords with no defaults must be last! */
  91         {"option",       udhcp_str2optset, &(server_config.options), ""},
  92         {"opt",          udhcp_str2optset, &(server_config.options), ""},
  93         {"notify_file",  read_str, &(server_config.notify_file),  ""},
  94         {"sname",        read_str, &(server_config.sname),        ""},
  95         {"boot_file",    read_str, &(server_config.boot_file),    ""},
  96         {"static_lease", read_staticlease, &(server_config.static_leases), ""},
  97 };
  98 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
  99
 100 void FAST_FUNC read_config(const char *file)
 101 {
 102         parser_t *parser;
 103         const struct config_keyword *k;
 104         unsigned i;
 105         char *token[2];
 106
 107         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 108                 keywords[i].handler(keywords[i].def, keywords[i].var);
 109
 110         parser = config_open(file);
 111         while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
 112                 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
 113                         if (strcasecmp(token[0], k->keyword) == 0) {
 114                                 if (!k->handler(token[1], k->var)) {
 115                                         bb_error_msg("can't parse line %u in %s",
 116                                                         parser->lineno, file);
 117                                         /* reset back to the default value */
 118                                         k->handler(k->def, k->var);
 119                                 }
 120                                 break;
 121                         }
 122                 }
 123         }
 124         config_close(parser);
 125
 126         server_config.start_ip = ntohl(server_config.start_ip);
 127         server_config.end_ip = ntohl(server_config.end_ip);
 128 }
 129
 130 void FAST_FUNC write_leases(void)
 131 {
 132         int fd;
 133         unsigned i;
 134         leasetime_t curr;
 135         int64_t written_at;
 136
 137         fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 138         if (fd < 0)
 139                 return;
 140
 141         curr = written_at = time(NULL);
 142
 143         written_at = hton64(written_at);
 144         full_write(fd, &written_at, sizeof(written_at));
 145
 146         for (i = 0; i < server_config.max_leases; i++) {
 147                 leasetime_t tmp_time;
 148
 149                 if (g_leases[i].lease_nip == 0)
 150                         continue;
 151
 152                 /* Screw with the time in the struct, for easier writing */
 153                 tmp_time = g_leases[i].expires;
 154
 155                 g_leases[i].expires -= curr;
 156                 if ((signed_leasetime_t) g_leases[i].expires < 0)
 157                         g_leases[i].expires = 0;
 158                 g_leases[i].expires = htonl(g_leases[i].expires);
 159
 160                 /* No error check. If the file gets truncated,
 161                  * we lose some leases on restart. Oh well. */
 162                 full_write(fd, &g_leases[i], sizeof(g_leases[i]));
 163
 164                 /* Then restore it when done */
 165                 g_leases[i].expires = tmp_time;
 166         }
 167         close(fd);
 168
 169         if (server_config.notify_file) {
 170                 char *argv[3];
 171                 argv[0] = server_config.notify_file;
 172                 argv[1] = server_config.lease_file;
 173                 argv[2] = NULL;
 174                 spawn_and_wait(argv);
 175         }
 176 }
 177
 178 void FAST_FUNC read_leases(const char *file)
 179 {
 180         struct dyn_lease lease;
 181         int64_t written_at, time_passed;
 182         int fd;
 183 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 184         unsigned i = 0;
 185 #endif
 186
 187         fd = open_or_warn(file, O_RDONLY);
 188         if (fd < 0)
 189                 return;
 190
 191         if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
 192                 goto ret;
 193         written_at = ntoh64(written_at);
 194
 195         time_passed = time(NULL) - written_at;
 196         /* Strange written_at, or lease file from old version of udhcpd
 197          * which had no "written_at" field? */
 198         if ((uint64_t)time_passed > 12 * 60 * 60)
 199                 goto ret;
 200
 201         while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
 202 //FIXME: what if it matches some static lease?
 203                 uint32_t y = ntohl(lease.lease_nip);
 204                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 205                         signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
 206                         if (expires <= 0)
 207                                 continue;
 208                         /* NB: add_lease takes "relative time", IOW,
 209                          * lease duration, not lease deadline. */
 210                         if (add_lease(lease.lease_mac, lease.lease_nip,
 211                                         expires,
 212                                         lease.hostname, sizeof(lease.hostname)
 213                                 ) == 0
 214                         ) {
 215                                 bb_error_msg("too many leases while loading %s", file);
 216                                 break;
 217                         }
 218 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 219                         i++;
 220 #endif
 221                 }
 222         }
 223         log1("Read %d leases", i);
 224  ret:
 225         close(fd);
 226 }