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 max_option_length[] = {
  18         [OPTION_IP] =           sizeof("255.255.255.255 "),
  19         [OPTION_IP_PAIR] =      sizeof("255.255.255.255 ") * 2,
  20         [OPTION_STRING] =       1,
  21 #if ENABLE_FEATURE_UDHCP_RFC3397
  22         [OPTION_STR1035] =      1,
  23 #endif
  24         [OPTION_BOOLEAN] =      sizeof("yes "),
  25         [OPTION_U8] =           sizeof("255 "),
  26         [OPTION_U16] =          sizeof("65535 "),
  27         [OPTION_S16] =          sizeof("-32768 "),
  28         [OPTION_U32] =          sizeof("4294967295 "),
  29         [OPTION_S32] =          sizeof("-2147483684 "),
  30 };
  31
  32
  33 static inline int upper_length(int length, int opt_index)
  34 {
  35         return max_option_length[opt_index] *
  36                 (length / dhcp_option_lengths[opt_index]);
  37 }
  38
  39
  40 /* note: ip is a pointer to an IP in network order, possibly misaliged */
  41 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
  42 {
  43         return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
  44 }
  45
  46
  47 /* really simple implementation, just count the bits */
  48 static int mton(uint32_t mask)
  49 {
  50         int i = 0;
  51         mask = ntohl(mask); /* 111110000-like bit pattern */
  52         while (mask) {
  53                 i++;
  54                 mask <<= 1;
  55         }
  56         return i;
  57 }
  58
  59
  60 /* Allocate and fill with the text of option 'option'. */
  61 static char *alloc_fill_opts(uint8_t *option, const struct dhcp_option *type_p, const char *opt_name)
  62 {
  63         int len, type, optlen;
  64         uint16_t val_u16;
  65         int16_t val_s16;
  66         uint32_t val_u32;
  67         int32_t val_s32;
  68         char *dest, *ret;
  69
  70         len = option[OPT_LEN - 2];
  71         type = type_p->flags & TYPE_MASK;
  72         optlen = dhcp_option_lengths[type];
  73
  74         dest = ret = xmalloc(upper_length(len, type) + strlen(opt_name) + 2);
  75         dest += sprintf(ret, "%s=", opt_name);
  76
  77         for (;;) {
  78                 switch (type) {
  79                 case OPTION_IP_PAIR:
  80                         dest += sprint_nip(dest, "", option);
  81                         *dest++ = '/';
  82                         option += 4;
  83                         optlen = 4;
  84                 case OPTION_IP: /* Works regardless of host byte order. */
  85                         dest += sprint_nip(dest, "", option);
  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 #if ENABLE_FEATURE_UDHCP_RFC3397
 114                 case OPTION_STR1035:
 115                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 116                         dest = dname_dec(option, len, ret);
 117                         free(ret);
 118                         return dest;
 119 #endif
 120                 }
 121                 option += optlen;
 122                 len -= optlen;
 123                 if (len <= 0)
 124                         break;
 125                 dest += sprintf(dest, " ");
 126         }
 127         return ret;
 128 }
 129
 130
 131 /* put all the parameters into an environment */
 132 static char **fill_envp(struct dhcp_packet *packet)
 133 {
 134         int num_options = 0;
 135         int i;
 136         char **envp, **curr;
 137         const char *opt_name;
 138         uint8_t *temp;
 139         uint8_t over = 0;
 140
 141         if (packet) {
 142                 for (i = 0; dhcp_options[i].code; i++) {
 143                         if (get_option(packet, dhcp_options[i].code)) {
 144                                 num_options++;
 145                                 if (dhcp_options[i].code == DHCP_SUBNET)
 146                                         num_options++; /* for mton */
 147                         }
 148                 }
 149                 if (packet->siaddr_nip)
 150                         num_options++;
 151                 temp = get_option(packet, DHCP_OPTION_OVERLOAD);
 152                 if (temp)
 153                         over = *temp;
 154                 if (!(over & FILE_FIELD) && packet->file[0])
 155                         num_options++;
 156                 if (!(over & SNAME_FIELD) && packet->sname[0])
 157                         num_options++;
 158         }
 159
 160         curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
 161         *curr = xasprintf("interface=%s", client_config.interface);
 162         putenv(*curr++);
 163
 164         if (packet == NULL)
 165                 return envp;
 166
 167         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 168         sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 169         putenv(*curr++);
 170
 171         opt_name = dhcp_option_strings;
 172         i = 0;
 173         while (*opt_name) {
 174                 temp = get_option(packet, dhcp_options[i].code);
 175                 if (!temp)
 176                         goto next;
 177                 *curr = alloc_fill_opts(temp, &dhcp_options[i], opt_name);
 178                 putenv(*curr++);
 179
 180                 /* Fill in a subnet bits option for things like /24 */
 181                 if (dhcp_options[i].code == DHCP_SUBNET) {
 182                         uint32_t subnet;
 183                         move_from_unaligned32(subnet, temp);
 184                         *curr = xasprintf("mask=%d", mton(subnet));
 185                         putenv(*curr++);
 186                 }
 187  next:
 188                 opt_name += strlen(opt_name) + 1;
 189                 i++;
 190         }
 191         if (packet->siaddr_nip) {
 192                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 193                 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 194                 putenv(*curr++);
 195         }
 196         if (!(over & FILE_FIELD) && packet->file[0]) {
 197                 /* watch out for invalid packets */
 198                 packet->file[sizeof(packet->file) - 1] = '\0';
 199                 *curr = xasprintf("boot_file=%s", packet->file);
 200                 putenv(*curr++);
 201         }
 202         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 203                 /* watch out for invalid packets */
 204                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 205                 *curr = xasprintf("sname=%s", packet->sname);
 206                 putenv(*curr++);
 207         }
 208         return envp;
 209 }
 210
 211
 212 /* Call a script with a par file and env vars */
 213 void FAST_FUNC udhcp_run_script(struct dhcp_packet *packet, const char *name)
 214 {
 215         char **envp, **curr;
 216         char *argv[3];
 217
 218         if (client_config.script == NULL)
 219                 return;
 220
 221         log1("Executing %s", client_config.script);
 222
 223         envp = fill_envp(packet);
 224
 225         /* call script */
 226         argv[0] = (char*) client_config.script;
 227         argv[1] = (char*) name;
 228         argv[2] = NULL;
 229         wait4pid(spawn(argv));
 230
 231         for (curr = envp; *curr; curr++) {
 232                 bb_unsetenv(*curr);
 233                 free(*curr);
 234         }
 235         free(envp);
 236 }