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: /* Works regardless of host byte order. */
  82                         dest += sprint_nip(dest, "", option);
  83                         break;
  84                 case OPTION_BOOLEAN:
  85                         dest += sprintf(dest, *option ? "yes" : "no");
  86                         break;
  87                 case OPTION_U8:
  88                         dest += sprintf(dest, "%u", *option);
  89                         break;
  90                 case OPTION_U16:
  91                         move_from_unaligned16(val_u16, option);
  92                         dest += sprintf(dest, "%u", ntohs(val_u16));
  93                         break;
  94                 case OPTION_S16:
  95                         move_from_unaligned16(val_s16, option);
  96                         dest += sprintf(dest, "%d", ntohs(val_s16));
  97                         break;
  98                 case OPTION_U32:
  99                         move_from_unaligned32(val_u32, option);
 100                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 101                         break;
 102                 case OPTION_S32:
 103                         move_from_unaligned32(val_s32, option);
 104                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 105                         break;
 106                 case OPTION_STRING:
 107                         memcpy(dest, option, len);
 108                         dest[len] = '\0';
 109                         return ret;      /* Short circuit this case */
 110                 case OPTION_STATIC_ROUTES: {
 111                         /* Option binary format:
 112                          * mask [one byte, 0..32]
 113                          * ip [big endian, 0..4 bytes depending on mask]
 114                          * router [big endian, 4 bytes]
 115                          * may be repeated
 116                          *
 117                          * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
 118                          */
 119                         const char *pfx = "";
 120
 121                         while (len >= 1 + 4) { /* mask + 0-byte ip + router */
 122                                 uint32_t nip;
 123                                 uint8_t *p;
 124                                 unsigned mask;
 125                                 int bytes;
 126
 127                                 mask = *option++;
 128                                 if (mask > 32)
 129                                         break;
 130                                 len--;
 131
 132                                 nip = 0;
 133                                 p = (void*) &nip;
 134                                 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
 135                                 while (--bytes >= 0) {
 136                                         *p++ = *option++;
 137                                         len--;
 138                                 }
 139                                 if (len < 4)
 140                                         break;
 141
 142                                 /* print ip/mask */
 143                                 dest += sprint_nip(dest, pfx, (void*) &nip);
 144                                 pfx = " ";
 145                                 dest += sprintf(dest, "/%u ", mask);
 146                                 /* print router */
 147                                 dest += sprint_nip(dest, "", option);
 148                                 option += 4;
 149                                 len -= 4;
 150                         }
 151
 152                         return ret;
 153                 }
 154 #if ENABLE_FEATURE_UDHCP_RFC3397
 155                 case OPTION_STR1035:
 156                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 157                         dest = dname_dec(option, len, ret);
 158                         if (dest) {
 159                                 free(ret);
 160                                 return dest;
 161                         }
 162                         /* error. return "optname=" string */
 163                         return ret;
 164 #endif
 165                 }
 166                 option += optlen;
 167                 len -= optlen;
 168                 if (len <= 0)
 169                         break;
 170                 *dest++ = ' ';
 171                 *dest = '\0';
 172         }
 173         return ret;
 174 }
 175
 176
 177 /* put all the parameters into an environment */
 178 static char **fill_envp(struct dhcp_packet *packet)
 179 {
 180         int num_options = 0;
 181         int i;
 182         char **envp, **curr;
 183         const char *opt_name;
 184         uint8_t *temp;
 185         uint8_t over = 0;
 186
 187         if (packet) {
 188                 for (i = 0; dhcp_options[i].code; i++) {
 189                         if (get_option(packet, dhcp_options[i].code)) {
 190                                 num_options++;
 191                                 if (dhcp_options[i].code == DHCP_SUBNET)
 192                                         num_options++; /* for mton */
 193                         }
 194                 }
 195                 if (packet->siaddr_nip)
 196                         num_options++;
 197                 temp = get_option(packet, DHCP_OPTION_OVERLOAD);
 198                 if (temp)
 199                         over = *temp;
 200                 if (!(over & FILE_FIELD) && packet->file[0])
 201                         num_options++;
 202                 if (!(over & SNAME_FIELD) && packet->sname[0])
 203                         num_options++;
 204         }
 205
 206         curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
 207         *curr = xasprintf("interface=%s", client_config.interface);
 208         putenv(*curr++);
 209
 210         if (packet == NULL)
 211                 return envp;
 212
 213         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 214         sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 215         putenv(*curr++);
 216
 217         opt_name = dhcp_option_strings;
 218         i = 0;
 219         while (*opt_name) {
 220                 temp = get_option(packet, dhcp_options[i].code);
 221                 if (!temp)
 222                         goto next;
 223                 *curr = xmalloc_optname_optval(temp, &dhcp_options[i], opt_name);
 224                 putenv(*curr++);
 225
 226                 /* Fill in a subnet bits option for things like /24 */
 227                 if (dhcp_options[i].code == DHCP_SUBNET) {
 228                         uint32_t subnet;
 229                         move_from_unaligned32(subnet, temp);
 230                         *curr = xasprintf("mask=%d", mton(subnet));
 231                         putenv(*curr++);
 232                 }
 233  next:
 234                 opt_name += strlen(opt_name) + 1;
 235                 i++;
 236         }
 237         if (packet->siaddr_nip) {
 238                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 239                 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 240                 putenv(*curr++);
 241         }
 242         if (!(over & FILE_FIELD) && packet->file[0]) {
 243                 /* watch out for invalid packets */
 244                 packet->file[sizeof(packet->file) - 1] = '\0';
 245                 *curr = xasprintf("boot_file=%s", packet->file);
 246                 putenv(*curr++);
 247         }
 248         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 249                 /* watch out for invalid packets */
 250                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 251                 *curr = xasprintf("sname=%s", packet->sname);
 252                 putenv(*curr++);
 253         }
 254         return envp;
 255 }
 256
 257
 258 /* Call a script with a par file and env vars */
 259 void FAST_FUNC udhcp_run_script(struct dhcp_packet *packet, const char *name)
 260 {
 261         char **envp, **curr;
 262         char *argv[3];
 263
 264         if (client_config.script == NULL)
 265                 return;
 266
 267         envp = fill_envp(packet);
 268
 269         /* call script */
 270         log1("Executing %s %s", client_config.script, name);
 271         argv[0] = (char*) client_config.script;
 272         argv[1] = (char*) name;
 273         argv[2] = NULL;
 274         wait4pid(spawn(argv));
 275
 276         for (curr = envp; *curr; curr++) {
 277                 log2(" %s", *curr);
 278                 bb_unsetenv(*curr);
 279                 free(*curr);
 280         }
 281         free(envp);
 282 }