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 static int sprintip(char *dest, const char *pre, const uint8_t *ip)
  41 {
  42         return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
  43 }
  44
  45
  46 /* really simple implementation, just count the bits */
  47 static int mton(uint32_t mask)
  48 {
  49         int i = 0;
  50         mask = ntohl(mask); /* 111110000-like bit pattern */
  51         while (mask) {
  52                 i++;
  53                 mask <<= 1;
  54         }
  55         return i;
  56 }
  57
  58
  59 /* Allocate and fill with the text of option 'option'. */
  60 static char *alloc_fill_opts(uint8_t *option, const struct dhcp_option *type_p, const char *opt_name)
  61 {
  62         int len, type, optlen;
  63         uint16_t val_u16;
  64         int16_t val_s16;
  65         uint32_t val_u32;
  66         int32_t val_s32;
  67         char *dest, *ret;
  68
  69         len = option[OPT_LEN - 2];
  70         type = type_p->flags & TYPE_MASK;
  71         optlen = dhcp_option_lengths[type];
  72
  73         dest = ret = xmalloc(upper_length(len, type) + strlen(opt_name) + 2);
  74         dest += sprintf(ret, "%s=", opt_name);
  75
  76         for (;;) {
  77                 switch (type) {
  78                 case OPTION_IP_PAIR:
  79                         dest += sprintip(dest, "", option);
  80                         *dest++ = '/';
  81                         option += 4;
  82                         optlen = 4;
  83                 case OPTION_IP: /* Works regardless of host byte order. */
  84                         dest += sprintip(dest, "", option);
  85                         break;
  86                 case OPTION_BOOLEAN:
  87                         dest += sprintf(dest, *option ? "yes" : "no");
  88                         break;
  89                 case OPTION_U8:
  90                         dest += sprintf(dest, "%u", *option);
  91                         break;
  92                 case OPTION_U16:
  93                         move_from_unaligned16(val_u16, option);
  94                         dest += sprintf(dest, "%u", ntohs(val_u16));
  95                         break;
  96                 case OPTION_S16:
  97                         move_from_unaligned16(val_s16, option);
  98                         dest += sprintf(dest, "%d", ntohs(val_s16));
  99                         break;
 100                 case OPTION_U32:
 101                         move_from_unaligned32(val_u32, option);
 102                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 103                         break;
 104                 case OPTION_S32:
 105                         move_from_unaligned32(val_s32, option);
 106                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 107                         break;
 108                 case OPTION_STRING:
 109                         memcpy(dest, option, len);
 110                         dest[len] = '\0';
 111                         return ret;      /* Short circuit this case */
 112 #if ENABLE_FEATURE_UDHCP_RFC3397
 113                 case OPTION_STR1035:
 114                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 115                         dest = dname_dec(option, len, ret);
 116                         free(ret);
 117                         return dest;
 118 #endif
 119                 }
 120                 option += optlen;
 121                 len -= optlen;
 122                 if (len <= 0)
 123                         break;
 124                 dest += sprintf(dest, " ");
 125         }
 126         return ret;
 127 }
 128
 129
 130 /* put all the parameters into an environment */
 131 static char **fill_envp(struct dhcpMessage *packet)
 132 {
 133         int num_options = 0;
 134         int i;
 135         char **envp, **curr;
 136         const char *opt_name;
 137         uint8_t *temp;
 138         char over = 0;
 139
 140         if (packet) {
 141                 for (i = 0; dhcp_options[i].code; i++) {
 142                         if (get_option(packet, dhcp_options[i].code)) {
 143                                 num_options++;
 144                                 if (dhcp_options[i].code == DHCP_SUBNET)
 145                                         num_options++; /* for mton */
 146                         }
 147                 }
 148                 if (packet->siaddr)
 149                         num_options++;
 150                 temp = get_option(packet, DHCP_OPTION_OVER);
 151                 if (temp)
 152                         over = *temp;
 153                 if (!(over & FILE_FIELD) && packet->file[0])
 154                         num_options++;
 155                 if (!(over & SNAME_FIELD) && packet->sname[0])
 156                         num_options++;
 157         }
 158
 159         curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
 160         *curr = xasprintf("interface=%s", client_config.interface);
 161         putenv(*curr++);
 162
 163         if (packet == NULL)
 164                 return envp;
 165
 166         *curr = xmalloc(sizeof("ip=255.255.255.255"));
 167         sprintip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
 168         putenv(*curr++);
 169
 170         opt_name = dhcp_option_strings;
 171         i = 0;
 172         while (*opt_name) {
 173                 temp = get_option(packet, dhcp_options[i].code);
 174                 if (!temp)
 175                         goto next;
 176                 *curr = alloc_fill_opts(temp, &dhcp_options[i], opt_name);
 177                 putenv(*curr++);
 178
 179                 /* Fill in a subnet bits option for things like /24 */
 180                 if (dhcp_options[i].code == DHCP_SUBNET) {
 181                         uint32_t subnet;
 182                         move_from_unaligned32(subnet, temp);
 183                         *curr = xasprintf("mask=%d", mton(subnet));
 184                         putenv(*curr++);
 185                 }
 186  next:
 187                 opt_name += strlen(opt_name) + 1;
 188                 i++;
 189         }
 190         if (packet->siaddr) {
 191                 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
 192                 sprintip(*curr, "siaddr=", (uint8_t *) &packet->siaddr);
 193                 putenv(*curr++);
 194         }
 195         if (!(over & FILE_FIELD) && packet->file[0]) {
 196                 /* watch out for invalid packets */
 197                 packet->file[sizeof(packet->file) - 1] = '\0';
 198                 *curr = xasprintf("boot_file=%s", packet->file);
 199                 putenv(*curr++);
 200         }
 201         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 202                 /* watch out for invalid packets */
 203                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 204                 *curr = xasprintf("sname=%s", packet->sname);
 205                 putenv(*curr++);
 206         }
 207         return envp;
 208 }
 209
 210
 211 /* Call a script with a par file and env vars */
 212 void FAST_FUNC udhcp_run_script(struct dhcpMessage *packet, const char *name)
 213 {
 214         char **envp, **curr;
 215         char *argv[3];
 216
 217         if (client_config.script == NULL)
 218                 return;
 219
 220         DEBUG("vfork'ing and exec'ing %s", client_config.script);
 221
 222         envp = fill_envp(packet);
 223
 224         /* call script */
 225         argv[0] = (char*) client_config.script;
 226         argv[1] = (char*) name;
 227         argv[2] = NULL;
 228         wait4pid(spawn(argv));
 229
 230         for (curr = envp; *curr; curr++) {
 231                 bb_unsetenv(*curr);
 232                 free(*curr);
 233         }
 234         free(envp);
 235 }