networking/udhcp/files.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * DHCP server config and lease file manipulation
   4  *
   5  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   6  *
   7  * Licensed under GPLv2, see file LICENSE in this source tree.
   8  */
   9 #include <netinet/ether.h>
  10
  11 #include "common.h"
  12 #include "dhcpd.h"
  13
  14 /* on these functions, make sure your datatype matches */
  15 static int FAST_FUNC read_str(const char *line, void *arg)
  16 {
  17         char **dest = arg;
  18
  19         free(*dest);
  20         *dest = xstrdup(line);
  21         return 1;
  22 }
  23
  24 static int FAST_FUNC read_u32(const char *line, void *arg)
  25 {
  26         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  27         return errno == 0;
  28 }
  29
  30 static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
  31 {
  32         char *line;
  33         char *mac_string;
  34         char *ip_string;
  35         struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
  36         uint32_t nip;
  37
  38         /* Read mac */
  39         line = (char *) const_line;
  40         mac_string = strtok_r(line, " \t", &line);
  41         if (!mac_string || !ether_aton_r(mac_string, &mac_bytes))
  42                 return 0;
  43
  44         /* Read ip */
  45         ip_string = strtok_r(NULL, " \t", &line);
  46         if (!ip_string || !udhcp_str2nip(ip_string, &nip))
  47                 return 0;
  48
  49         add_static_lease(arg, (uint8_t*) &mac_bytes, nip);
  50
  51         log_static_leases(arg);
  52
  53         return 1;
  54 }
  55
  56
  57 struct config_keyword {
  58         const char *keyword;
  59         int (*handler)(const char *line, void *var) FAST_FUNC;
  60         unsigned ofs;
  61         const char *def;
  62 };
  63
  64 #define OFS(field) offsetof(struct server_config_t, field)
  65
  66 static const struct config_keyword keywords[] = {
  67         /* keyword        handler           variable address               default */
  68         {"start"        , udhcp_str2nip   , OFS(start_ip     ), "192.168.0.20"},
  69         {"end"          , udhcp_str2nip   , OFS(end_ip       ), "192.168.0.254"},
  70         {"interface"    , read_str        , OFS(interface    ), "eth0"},
  71         /* Avoid "max_leases value not sane" warning by setting default
  72          * to default_end_ip - default_start_ip + 1: */
  73         {"max_leases"   , read_u32        , OFS(max_leases   ), "235"},
  74         {"auto_time"    , read_u32        , OFS(auto_time    ), "7200"},
  75         {"decline_time" , read_u32        , OFS(decline_time ), "3600"},
  76         {"conflict_time", read_u32        , OFS(conflict_time), "3600"},
  77         {"offer_time"   , read_u32        , OFS(offer_time   ), "60"},
  78         {"min_lease"    , read_u32        , OFS(min_lease_sec), "60"},
  79         {"lease_file"   , read_str        , OFS(lease_file   ), LEASES_FILE},
  80         {"pidfile"      , read_str        , OFS(pidfile      ), "/var/run/udhcpd.pid"},
  81         {"siaddr"       , udhcp_str2nip   , OFS(siaddr_nip   ), "0.0.0.0"},
  82         /* keywords with no defaults must be last! */
  83         {"option"       , udhcp_str2optset, OFS(options      ), ""},
  84         {"opt"          , udhcp_str2optset, OFS(options      ), ""},
  85         {"notify_file"  , read_str        , OFS(notify_file  ), NULL},
  86         {"sname"        , read_str        , OFS(sname        ), NULL},
  87         {"boot_file"    , read_str        , OFS(boot_file    ), NULL},
  88         {"static_lease" , read_staticlease, OFS(static_leases), ""},
  89 };
  90 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
  91
  92 void FAST_FUNC read_config(const char *file)
  93 {
  94         parser_t *parser;
  95         const struct config_keyword *k;
  96         unsigned i;
  97         char *token[2];
  98
  99         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 100                 keywords[i].handler(keywords[i].def, (char*)&server_config + keywords[i].ofs);
 101
 102         parser = config_open(file);
 103         while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
 104                 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
 105                         if (strcasecmp(token[0], k->keyword) == 0) {
 106                                 if (!k->handler(token[1], (char*)&server_config + k->ofs)) {
 107                                         bb_error_msg("can't parse line %u in %s",
 108                                                         parser->lineno, file);
 109                                         /* reset back to the default value */
 110                                         k->handler(k->def, (char*)&server_config + k->ofs);
 111                                 }
 112                                 break;
 113                         }
 114                 }
 115         }
 116         config_close(parser);
 117
 118         server_config.start_ip = ntohl(server_config.start_ip);
 119         server_config.end_ip = ntohl(server_config.end_ip);
 120 }
 121
 122 void FAST_FUNC write_leases(void)
 123 {
 124         int fd;
 125         unsigned i;
 126         leasetime_t curr;
 127         int64_t written_at;
 128
 129         fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 130         if (fd < 0)
 131                 return;
 132
 133         curr = written_at = time(NULL);
 134
 135         written_at = SWAP_BE64(written_at);
 136         full_write(fd, &written_at, sizeof(written_at));
 137
 138         for (i = 0; i < server_config.max_leases; i++) {
 139                 leasetime_t tmp_time;
 140
 141                 if (g_leases[i].lease_nip == 0)
 142                         continue;
 143
 144                 /* Screw with the time in the struct, for easier writing */
 145                 tmp_time = g_leases[i].expires;
 146
 147                 g_leases[i].expires -= curr;
 148                 if ((signed_leasetime_t) g_leases[i].expires < 0)
 149                         g_leases[i].expires = 0;
 150                 g_leases[i].expires = htonl(g_leases[i].expires);
 151
 152                 /* No error check. If the file gets truncated,
 153                  * we lose some leases on restart. Oh well. */
 154                 full_write(fd, &g_leases[i], sizeof(g_leases[i]));
 155
 156                 /* Then restore it when done */
 157                 g_leases[i].expires = tmp_time;
 158         }
 159         close(fd);
 160
 161         if (server_config.notify_file) {
 162                 char *argv[3];
 163                 argv[0] = server_config.notify_file;
 164                 argv[1] = server_config.lease_file;
 165                 argv[2] = NULL;
 166                 spawn_and_wait(argv);
 167         }
 168 }
 169
 170 void FAST_FUNC read_leases(const char *file)
 171 {
 172         struct dyn_lease lease;
 173         int64_t written_at, time_passed;
 174         int fd;
 175 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 176         unsigned i = 0;
 177 #endif
 178
 179         fd = open_or_warn(file, O_RDONLY);
 180         if (fd < 0)
 181                 return;
 182
 183         if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
 184                 goto ret;
 185         written_at = SWAP_BE64(written_at);
 186
 187         time_passed = time(NULL) - written_at;
 188         /* Strange written_at, or lease file from old version of udhcpd
 189          * which had no "written_at" field? */
 190         if ((uint64_t)time_passed > 12 * 60 * 60)
 191                 goto ret;
 192
 193         while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
 194                 uint32_t y = ntohl(lease.lease_nip);
 195                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 196                         signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
 197                         uint32_t static_nip;
 198
 199                         if (expires <= 0)
 200                                 /* We keep expired leases: add_lease() will add
 201                                  * a lease with 0 seconds remaining.
 202                                  * Fewer IP address changes this way for mass reboot scenario.
 203                                  */
 204                                 expires = 0;
 205
 206                         /* Check if there is a different static lease for this IP or MAC */
 207                         static_nip = get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
 208                         if (static_nip) {
 209                                 /* NB: we do not add lease even if static_nip == lease.lease_nip.
 210                                  */
 211                                 continue;
 212                         }
 213                         if (is_nip_reserved(server_config.static_leases, lease.lease_nip))
 214                                 continue;
 215
 216                         /* NB: add_lease takes "relative time", IOW,
 217                          * lease duration, not lease deadline. */
 218                         if (add_lease(lease.lease_mac, lease.lease_nip,
 219                                         expires,
 220                                         lease.hostname, sizeof(lease.hostname)
 221                                 ) == 0
 222                         ) {
 223                                 bb_error_msg("too many leases while loading %s", file);
 224                                 break;
 225                         }
 226 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 227                         i++;
 228 #endif
 229                 }
 230         }
 231         log1("read %d leases", i);
 232  ret:
 233         close(fd);
 234 }