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 "dhcpd.h"
  13 #include "dhcpc.h"
  14 #include "options.h"
  15
  16
  17 /* get a rough idea of how long an option will be (rounding up...) */
  18 static const int max_option_length[] = {
  19         [OPTION_IP] =           sizeof("255.255.255.255 "),
  20         [OPTION_IP_PAIR] =      sizeof("255.255.255.255 ") * 2,
  21         [OPTION_STRING] =       1,
  22 #if ENABLE_FEATURE_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 static inline int upper_length(int length, int opt_index)
  35 {
  36         return max_option_length[opt_index] *
  37                 (length / option_lengths[opt_index]);
  38 }
  39
  40
  41 static int sprintip(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(struct in_addr *mask)
  49 {
  50         int i;
  51         unsigned long bits = ntohl(mask->s_addr);
  52         /* too bad one can't check the carry bit, etc in c bit
  53          * shifting */
  54         for (i = 0; i < 32 && !((bits >> i) & 1); i++);
  55         return 32 - 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)
  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 = option_lengths[type];
  72
  73         dest = ret = xmalloc(upper_length(len, type) + strlen(type_p->name) + 2);
  74         dest += sprintf(ret, "%s=", type_p->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                         memcpy(&val_u16, option, 2);
  94                         dest += sprintf(dest, "%u", ntohs(val_u16));
  95                         break;
  96                 case OPTION_S16:
  97                         memcpy(&val_s16, option, 2);
  98                         dest += sprintf(dest, "%d", ntohs(val_s16));
  99                         break;
 100                 case OPTION_U32:
 101                         memcpy(&val_u32, option, 4);
 102                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 103                         break;
 104                 case OPTION_S32:
 105                         memcpy(&val_s32, option, 4);
 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_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) break;
 123                 dest += sprintf(dest, " ");
 124         }
 125         return ret;
 126 }
 127
 128
 129 /* put all the parameters into an environment */
 130 static char **fill_envp(struct dhcpMessage *packet)
 131 {
 132         int num_options = 0;
 133         int i, j;
 134         char **envp;
 135         uint8_t *temp;
 136         struct in_addr subnet;
 137         char over = 0;
 138
 139         if (packet == NULL)
 140                 num_options = 0;
 141         else {
 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                 if (packet->siaddr) num_options++;
 149                 if ((temp = get_option(packet, DHCP_OPTION_OVER)))
 150                         over = *temp;
 151                 if (!(over & FILE_FIELD) && packet->file[0]) num_options++;
 152                 if (!(over & SNAME_FIELD) && packet->sname[0]) num_options++;
 153         }
 154
 155         envp = xzalloc(sizeof(char *) * (num_options + 5));
 156         j = 0;
 157         envp[j++] = xasprintf("interface=%s", client_config.interface);
 158         envp[j++] = xasprintf("PATH=%s",
 159                 getenv("PATH") ? : "/bin:/usr/bin:/sbin:/usr/sbin");
 160         envp[j++] = xasprintf("HOME=%s", getenv("HOME") ? : "/");
 161
 162         if (packet == NULL) return envp;
 163
 164         envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
 165         sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
 166
 167         for (i = 0; dhcp_options[i].code; i++) {
 168                 temp = get_option(packet, dhcp_options[i].code);
 169                 if (!temp)
 170                         continue;
 171                 envp[j++] = alloc_fill_opts(temp, &dhcp_options[i]);
 172
 173                 /* Fill in a subnet bits option for things like /24 */
 174                 if (dhcp_options[i].code == DHCP_SUBNET) {
 175                         memcpy(&subnet, temp, 4);
 176                         envp[j++] = xasprintf("mask=%d", mton(&subnet));
 177                 }
 178         }
 179         if (packet->siaddr) {
 180                 envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
 181                 sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
 182         }
 183         if (!(over & FILE_FIELD) && packet->file[0]) {
 184                 /* watch out for invalid packets */
 185                 packet->file[sizeof(packet->file) - 1] = '\0';
 186                 envp[j++] = xasprintf("boot_file=%s", packet->file);
 187         }
 188         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 189                 /* watch out for invalid packets */
 190                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 191                 envp[j++] = xasprintf("sname=%s", packet->sname);
 192         }
 193         return envp;
 194 }
 195
 196
 197 /* Call a script with a par file and env vars */
 198 void udhcp_run_script(struct dhcpMessage *packet, const char *name)
 199 {
 200         int pid;
 201         char **envp, **curr;
 202
 203         if (client_config.script == NULL)
 204                 return;
 205
 206         DEBUG("vfork'ing and execle'ing %s", client_config.script);
 207
 208         envp = fill_envp(packet);
 209         /* call script */
 210         pid = vfork();
 211         if (pid) {
 212                 waitpid(pid, NULL, 0);
 213                 for (curr = envp; *curr; curr++) free(*curr);
 214                 free(envp);
 215                 return;
 216         } else if (pid == 0) {
 217                 /* close fd's? */
 218                 /* exec script */
 219                 execle(client_config.script, client_config.script,
 220                        name, NULL, envp);
 221                 bb_perror_msg("script %s failed", client_config.script);
 222                 exit(1);
 223         }
 224 }