networking/udhcp/script.c

   1 /* vi: set sw=4 ts=4: */
   2 /* script.c
   3  *
   4  * Functions to call the DHCP client notification scripts
   5  *
   6  * Russ Dill <Russ.Dill@asu.edu> July 2001
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   9  */
  10
  11 #include "common.h"
  12 #include "dhcpc.h"
  13 #include "options.h"
  14
  15
  16 /* get a rough idea of how long an option will be (rounding up...) */
  17 static const uint8_t len_of_option_as_string[] = {
  18         [OPTION_IP] =           sizeof("255.255.255.255 "),
  19         [OPTION_IP_PAIR] =      sizeof("255.255.255.255 ") * 2,
  20         [OPTION_STATIC_ROUTES]= sizeof("255.255.255.255/32 255.255.255.255 "),
  21         [OPTION_STRING] =       1,
  22 #if ENABLE_FEATURE_UDHCP_RFC3397
  23         [OPTION_STR1035] =      1,
  24 #endif
  25         [OPTION_BOOLEAN] =      sizeof("yes "),
  26         [OPTION_U8] =           sizeof("255 "),
  27         [OPTION_U16] =          sizeof("65535 "),
  28         [OPTION_S16] =          sizeof("-32768 "),
  29         [OPTION_U32] =          sizeof("4294967295 "),
  30         [OPTION_S32] =          sizeof("-2147483684 "),
  31 };
  32
  33
  34 /* note: ip is a pointer to an IP in network order, possibly misaliged */
  35 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
  36 {
  37         return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
  38 }
  39
  40
  41 /* really simple implementation, just count the bits */
  42 static int mton(uint32_t mask)
  43 {
  44         int i = 0;
  45         mask = ntohl(mask); /* 111110000-like bit pattern */
  46         while (mask) {
  47                 i++;
  48                 mask <<= 1;
  49         }
  50         return i;
  51 }
  52
  53
  54 /* Create "opt_name=opt_value" string */
  55 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_option *type_p, const char *opt_name)
  56 {
  57         unsigned upper_length;
  58         int len, type, optlen;
  59         uint16_t val_u16;
  60         int16_t val_s16;
  61         uint32_t val_u32;
  62         int32_t val_s32;
  63         char *dest, *ret;
  64
  65         /* option points to OPT_DATA, need to go back and get OPT_LEN */
  66         len = option[OPT_LEN - OPT_DATA];
  67         type = type_p->flags & TYPE_MASK;
  68         optlen = dhcp_option_lengths[type];
  69         upper_length = len_of_option_as_string[type] * (len / optlen);
  70
  71         dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
  72         dest += sprintf(ret, "%s=", opt_name);
  73
  74         while (len >= optlen) {
  75                 switch (type) {
  76                 case OPTION_IP_PAIR:
  77                         dest += sprint_nip(dest, "", option);
  78                         *dest++ = '/';
  79                         option += 4;
  80                         optlen = 4;
  81                 case OPTION_IP:
  82                         dest += sprint_nip(dest, "", option);
  83 // TODO: it can be a list only if (type_p->flags & OPTION_LIST).
  84 // Should we bail out/warn if we see multi-ip option which is
  85 // not allowed to be such? For example, DHCP_BROADCAST...
  86                         break;
  87                 case OPTION_BOOLEAN:
  88                         dest += sprintf(dest, *option ? "yes" : "no");
  89                         break;
  90                 case OPTION_U8:
  91                         dest += sprintf(dest, "%u", *option);
  92                         break;
  93                 case OPTION_U16:
  94                         move_from_unaligned16(val_u16, option);
  95                         dest += sprintf(dest, "%u", ntohs(val_u16));
  96                         break;
  97                 case OPTION_S16:
  98                         move_from_unaligned16(val_s16, option);
  99                         dest += sprintf(dest, "%d", ntohs(val_s16));
 100                         break;
 101                 case OPTION_U32:
 102                         move_from_unaligned32(val_u32, option);
 103                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 104                         break;
 105                 case OPTION_S32:
 106                         move_from_unaligned32(val_s32, option);
 107                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 108                         break;
 109                 case OPTION_STRING:
 110                         memcpy(dest, option, len);
 111                         dest[len] = '\0';
 112                         return ret;      /* Short circuit this case */
 113                 case OPTION_STATIC_ROUTES: {
 114                         /* Option binary format:
 115                          * mask [one byte, 0..32]
 116                          * ip [big endian, 0..4 bytes depending on mask]
 117                          * router [big endian, 4 bytes]
 118                          * may be repeated
 119                          *
 120                          * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
 121                          */
 122                         const char *pfx = "";
 123
 124                         while (len >= 1 + 4) { /* mask + 0-byte ip + router */
 125                                 uint32_t nip;
 126                                 uint8_t *p;
 127                                 unsigned mask;
 128                                 int bytes;
 129
 130                                 mask = *option++;
 131                                 if (mask > 32)
 132                                         break;
 133                                 len--;
 134
 135                                 nip = 0;
 136                                 p = (void*) &nip;
 137                                 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
 138                                 while (--bytes >= 0) {
 139                                         *p++ = *option++;
 140                                         len--;
 141                                 }
 142                                 if (len < 4)
 143                                         break;
 144
 145                                 /* print ip/mask */
 146                                 dest += sprint_nip(dest, pfx, (void*) &nip);
 147                                 pfx = " ";
 148                                 dest += sprintf(dest, "/%u ", mask);
 149                                 /* print router */
 150                                 dest += sprint_nip(dest, "", option);
 151                                 option += 4;
 152                                 len -= 4;
 153                         }
 154
 155                         return ret;
 156                 }
 157 #if ENABLE_FEATURE_UDHCP_RFC3397
 158                 case OPTION_STR1035:
 159                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 160                         dest = dname_dec(option, len, ret);
 161                         if (dest) {
 162                                 free(ret);
 163                                 return dest;
 164                         }
 165                         /* error. return "optname=" string */
 166                         return ret;
 167 #endif
 168                 }
 169                 option += optlen;
 170                 len -= optlen;
 171                 if (len <= 0)
 172                         break;
 173                 *dest++ = ' ';
 174                 *dest = '\0';
 175         }
 176         return ret;
 177 }
 178
 179
 180 /* put all the parameters into the environment */
 181 static char **fill_envp(struct dhcp_packet *packet)
 182 {
 183         int num_options = 0;
 184         int i;
 185         char **envp, **curr;
 186         const char *opt_name;
 187         uint8_t *temp;
 188         uint8_t over = 0;
 189
 190         if (packet) {
 191                 for (i = 0; dhcp_options[i].code; i++) {
 192                         if (get_option(packet, dhcp_options[i].code)) {
 193                                 num_options++;
 194                                 if (dhcp_options[i].code == DHCP_SUBNET)
 195                                         num_options++; /* for mton */
 196                         }
 197                 }
 198                 if (packet->siaddr_nip)
 199                         num_options++;
 200                 temp = get_option(packet, DHCP_OPTION_OVERLOAD);
 201                 if (temp)
 202                         over = *temp;
 203                 if (!(over & FILE_FIELD) && packet->file[0])
 204                         num_options++;
 205                 if (!(over & SNAME_FIELD) && packet->sname[0])
 206                         num_options++;
 207         }
 208
 209         curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
 210         *curr = xasprintf("interface=%s", client_config.interface);
 211         putenv(*curr++);
 212
 213         if (packet == NULL)
 214                 return envp;
 215
 216         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 217         sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 218         putenv(*curr++);
 219
 220         opt_name = dhcp_option_strings;
 221         i = 0;
 222         while (*opt_name) {
 223                 temp = get_option(packet, dhcp_options[i].code);
 224                 if (!temp)
 225                         goto next;
 226                 *curr = xmalloc_optname_optval(temp, &dhcp_options[i], opt_name);
 227                 putenv(*curr++);
 228
 229                 /* Fill in a subnet bits option for things like /24 */
 230                 if (dhcp_options[i].code == DHCP_SUBNET) {
 231                         uint32_t subnet;
 232                         move_from_unaligned32(subnet, temp);
 233                         *curr = xasprintf("mask=%d", mton(subnet));
 234                         putenv(*curr++);
 235                 }
 236  next:
 237                 opt_name += strlen(opt_name) + 1;
 238                 i++;
 239         }
 240         if (packet->siaddr_nip) {
 241                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 242                 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 243                 putenv(*curr++);
 244         }
 245         if (!(over & FILE_FIELD) && packet->file[0]) {
 246                 /* watch out for invalid packets */
 247                 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
 248                 putenv(*curr++);
 249         }
 250         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 251                 /* watch out for invalid packets */
 252                 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
 253                 putenv(*curr++);
 254         }
 255         return envp;
 256 }
 257
 258
 259 /* Call a script with a par file and env vars */
 260 void FAST_FUNC udhcp_run_script(struct dhcp_packet *packet, const char *name)
 261 {
 262         char **envp, **curr;
 263         char *argv[3];
 264
 265         if (client_config.script == NULL)
 266                 return;
 267
 268         envp = fill_envp(packet);
 269
 270         /* call script */
 271         log1("Executing %s %s", client_config.script, name);
 272         argv[0] = (char*) client_config.script;
 273         argv[1] = (char*) name;
 274         argv[2] = NULL;
 275         spawn_and_wait(argv);
 276
 277         for (curr = envp; *curr; curr++) {
 278                 log2(" %s", *curr);
 279                 bb_unsetenv(*curr);
 280                 free(*curr);
 281         }
 282         free(envp);
 283 }