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         void *var;
  61         const char *def;
  62 };
  63
  64 static const struct config_keyword keywords[] = {
  65         /* keyword        handler           variable address               default */
  66         {"start"        , udhcp_str2nip   , &server_config.start_ip     , "192.168.0.20"},
  67         {"end"          , udhcp_str2nip   , &server_config.end_ip       , "192.168.0.254"},
  68         {"interface"    , read_str        , &server_config.interface    , "eth0"},
  69         /* Avoid "max_leases value not sane" warning by setting default
  70          * to default_end_ip - default_start_ip + 1: */
  71         {"max_leases"   , read_u32        , &server_config.max_leases   , "235"},
  72         {"auto_time"    , read_u32        , &server_config.auto_time    , "7200"},
  73         {"decline_time" , read_u32        , &server_config.decline_time , "3600"},
  74         {"conflict_time", read_u32        , &server_config.conflict_time, "3600"},
  75         {"offer_time"   , read_u32        , &server_config.offer_time   , "60"},
  76         {"min_lease"    , read_u32        , &server_config.min_lease_sec, "60"},
  77         {"lease_file"   , read_str        , &server_config.lease_file   , LEASES_FILE},
  78         {"pidfile"      , read_str        , &server_config.pidfile      , "/var/run/udhcpd.pid"},
  79         {"siaddr"       , udhcp_str2nip   , &server_config.siaddr_nip   , "0.0.0.0"},
  80         /* keywords with no defaults must be last! */
  81         {"option"       , udhcp_str2optset, &server_config.options      , ""},
  82         {"opt"          , udhcp_str2optset, &server_config.options      , ""},
  83         {"notify_file"  , read_str        , &server_config.notify_file  , NULL},
  84         {"sname"        , read_str        , &server_config.sname        , NULL},
  85         {"boot_file"    , read_str        , &server_config.boot_file    , NULL},
  86         {"static_lease" , read_staticlease, &server_config.static_leases, ""},
  87 };
  88 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
  89
  90 void FAST_FUNC read_config(const char *file)
  91 {
  92         parser_t *parser;
  93         const struct config_keyword *k;
  94         unsigned i;
  95         char *token[2];
  96
  97         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
  98                 keywords[i].handler(keywords[i].def, keywords[i].var);
  99
 100         parser = config_open(file);
 101         while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
 102                 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
 103                         if (strcasecmp(token[0], k->keyword) == 0) {
 104                                 if (!k->handler(token[1], k->var)) {
 105                                         bb_error_msg("can't parse line %u in %s",
 106                                                         parser->lineno, file);
 107                                         /* reset back to the default value */
 108                                         k->handler(k->def, k->var);
 109                                 }
 110                                 break;
 111                         }
 112                 }
 113         }
 114         config_close(parser);
 115
 116         server_config.start_ip = ntohl(server_config.start_ip);
 117         server_config.end_ip = ntohl(server_config.end_ip);
 118 }
 119
 120 void FAST_FUNC write_leases(void)
 121 {
 122         int fd;
 123         unsigned i;
 124         leasetime_t curr;
 125         int64_t written_at;
 126
 127         fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 128         if (fd < 0)
 129                 return;
 130
 131         curr = written_at = time(NULL);
 132
 133         written_at = SWAP_BE64(written_at);
 134         full_write(fd, &written_at, sizeof(written_at));
 135
 136         for (i = 0; i < server_config.max_leases; i++) {
 137                 leasetime_t tmp_time;
 138
 139                 if (g_leases[i].lease_nip == 0)
 140                         continue;
 141
 142                 /* Screw with the time in the struct, for easier writing */
 143                 tmp_time = g_leases[i].expires;
 144
 145                 g_leases[i].expires -= curr;
 146                 if ((signed_leasetime_t) g_leases[i].expires < 0)
 147                         g_leases[i].expires = 0;
 148                 g_leases[i].expires = htonl(g_leases[i].expires);
 149
 150                 /* No error check. If the file gets truncated,
 151                  * we lose some leases on restart. Oh well. */
 152                 full_write(fd, &g_leases[i], sizeof(g_leases[i]));
 153
 154                 /* Then restore it when done */
 155                 g_leases[i].expires = tmp_time;
 156         }
 157         close(fd);
 158
 159         if (server_config.notify_file) {
 160                 char *argv[3];
 161                 argv[0] = server_config.notify_file;
 162                 argv[1] = server_config.lease_file;
 163                 argv[2] = NULL;
 164                 spawn_and_wait(argv);
 165         }
 166 }
 167
 168 void FAST_FUNC read_leases(const char *file)
 169 {
 170         struct dyn_lease lease;
 171         int64_t written_at, time_passed;
 172         int fd;
 173 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 174         unsigned i = 0;
 175 #endif
 176
 177         fd = open_or_warn(file, O_RDONLY);
 178         if (fd < 0)
 179                 return;
 180
 181         if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
 182                 goto ret;
 183         written_at = SWAP_BE64(written_at);
 184
 185         time_passed = time(NULL) - written_at;
 186         /* Strange written_at, or lease file from old version of udhcpd
 187          * which had no "written_at" field? */
 188         if ((uint64_t)time_passed > 12 * 60 * 60)
 189                 goto ret;
 190
 191         while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
 192 //FIXME: what if it matches some static lease?
 193                 uint32_t y = ntohl(lease.lease_nip);
 194                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 195                         signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
 196                         if (expires <= 0)
 197                                 continue;
 198                         /* NB: add_lease takes "relative time", IOW,
 199                          * lease duration, not lease deadline. */
 200                         if (add_lease(lease.lease_mac, lease.lease_nip,
 201                                         expires,
 202                                         lease.hostname, sizeof(lease.hostname)
 203                                 ) == 0
 204                         ) {
 205                                 bb_error_msg("too many leases while loading %s", file);
 206                                 break;
 207                         }
 208 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 209                         i++;
 210 #endif
 211                 }
 212         }
 213         log1("Read %d leases", i);
 214  ret:
 215         close(fd);
 216 }