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         [OPTION_BOOLEAN] =      sizeof("yes "),
  23         [OPTION_U8] =           sizeof("255 "),
  24         [OPTION_U16] =          sizeof("65535 "),
  25         [OPTION_S16] =          sizeof("-32768 "),
  26         [OPTION_U32] =          sizeof("4294967295 "),
  27         [OPTION_S32] =          sizeof("-2147483684 "),
  28 };
  29
  30
  31 static inline int upper_length(int length, int opt_index)
  32 {
  33         return max_option_length[opt_index] *
  34                 (length / option_lengths[opt_index]);
  35 }
  36
  37
  38 static int sprintip(char *dest, char *pre, uint8_t *ip)
  39 {
  40         return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
  41 }
  42
  43
  44 /* really simple implementation, just count the bits */
  45 static int mton(struct in_addr *mask)
  46 {
  47         int i;
  48         unsigned long bits = ntohl(mask->s_addr);
  49         /* too bad one can't check the carry bit, etc in c bit
  50          * shifting */
  51         for (i = 0; i < 32 && !((bits >> i) & 1); i++);
  52         return 32 - i;
  53 }
  54
  55
  56 /* Fill dest with the text of option 'option'. */
  57 static void fill_options(char *dest, uint8_t *option,
  58                         const struct dhcp_option *type_p)
  59 {
  60         int type, optlen;
  61         uint16_t val_u16;
  62         int16_t val_s16;
  63         uint32_t val_u32;
  64         int32_t val_s32;
  65         int len = option[OPT_LEN - 2];
  66
  67         dest += sprintf(dest, "%s=", type_p->name);
  68
  69         type = type_p->flags & TYPE_MASK;
  70         optlen = option_lengths[type];
  71         for (;;) {
  72                 switch (type) {
  73                 case OPTION_IP_PAIR:
  74                         dest += sprintip(dest, "", option);
  75                         *(dest++) = '/';
  76                         option += 4;
  77                         optlen = 4;
  78                 case OPTION_IP: /* Works regardless of host byte order. */
  79                         dest += sprintip(dest, "", option);
  80                         break;
  81                 case OPTION_BOOLEAN:
  82                         dest += sprintf(dest, *option ? "yes" : "no");
  83                         break;
  84                 case OPTION_U8:
  85                         dest += sprintf(dest, "%u", *option);
  86                         break;
  87                 case OPTION_U16:
  88                         memcpy(&val_u16, option, 2);
  89                         dest += sprintf(dest, "%u", ntohs(val_u16));
  90                         break;
  91                 case OPTION_S16:
  92                         memcpy(&val_s16, option, 2);
  93                         dest += sprintf(dest, "%d", ntohs(val_s16));
  94                         break;
  95                 case OPTION_U32:
  96                         memcpy(&val_u32, option, 4);
  97                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
  98                         break;
  99                 case OPTION_S32:
 100                         memcpy(&val_s32, option, 4);
 101                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 102                         break;
 103                 case OPTION_STRING:
 104                         memcpy(dest, option, len);
 105                         dest[len] = '\0';
 106                         return;  /* Short circuit this case */
 107                 }
 108                 option += optlen;
 109                 len -= optlen;
 110                 if (len <= 0) break;
 111                 dest += sprintf(dest, " ");
 112         }
 113 }
 114
 115
 116 /* put all the parameters into an environment */
 117 static char **fill_envp(struct dhcpMessage *packet)
 118 {
 119         int num_options = 0;
 120         int i, j;
 121         char **envp;
 122         uint8_t *temp;
 123         struct in_addr subnet;
 124         char over = 0;
 125
 126         if (packet == NULL)
 127                 num_options = 0;
 128         else {
 129                 for (i = 0; dhcp_options[i].code; i++)
 130                         if (get_option(packet, dhcp_options[i].code)) {
 131                                 num_options++;
 132                                 if (dhcp_options[i].code == DHCP_SUBNET)
 133                                         num_options++; /* for mton */
 134                         }
 135                 if (packet->siaddr) num_options++;
 136                 if ((temp = get_option(packet, DHCP_OPTION_OVER)))
 137                         over = *temp;
 138                 if (!(over & FILE_FIELD) && packet->file[0]) num_options++;
 139                 if (!(over & SNAME_FIELD) && packet->sname[0]) num_options++;
 140         }
 141
 142         envp = xzalloc(sizeof(char *) * (num_options + 5));
 143         j = 0;
 144         envp[j++] = xasprintf("interface=%s", client_config.interface);
 145         envp[j++] = xasprintf("PATH=%s",
 146                 getenv("PATH") ? : "/bin:/usr/bin:/sbin:/usr/sbin");
 147         envp[j++] = xasprintf("HOME=%s", getenv("HOME") ? : "/");
 148
 149         if (packet == NULL) return envp;
 150
 151         envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
 152         sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
 153
 154         for (i = 0; dhcp_options[i].code; i++) {
 155                 temp = get_option(packet, dhcp_options[i].code);
 156                 if (!temp)
 157                         continue;
 158                 envp[j] = xmalloc(upper_length(temp[OPT_LEN - 2],
 159                         dhcp_options[i].flags & TYPE_MASK) + strlen(dhcp_options[i].name) + 2);
 160                 fill_options(envp[j++], temp, &dhcp_options[i]);
 161
 162                 /* Fill in a subnet bits option for things like /24 */
 163                 if (dhcp_options[i].code == DHCP_SUBNET) {
 164                         memcpy(&subnet, temp, 4);
 165                         envp[j++] = xasprintf("mask=%d", mton(&subnet));
 166                 }
 167         }
 168         if (packet->siaddr) {
 169                 envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
 170                 sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
 171         }
 172         if (!(over & FILE_FIELD) && packet->file[0]) {
 173                 /* watch out for invalid packets */
 174                 packet->file[sizeof(packet->file) - 1] = '\0';
 175                 envp[j++] = xasprintf("boot_file=%s", packet->file);
 176         }
 177         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 178                 /* watch out for invalid packets */
 179                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 180                 envp[j++] = xasprintf("sname=%s", packet->sname);
 181         }
 182         return envp;
 183 }
 184
 185
 186 /* Call a script with a par file and env vars */
 187 void udhcp_run_script(struct dhcpMessage *packet, const char *name)
 188 {
 189         int pid;
 190         char **envp, **curr;
 191
 192         if (client_config.script == NULL)
 193                 return;
 194
 195         DEBUG("vfork'ing and execle'ing %s", client_config.script);
 196
 197         envp = fill_envp(packet);
 198         /* call script */
 199         pid = vfork();
 200         if (pid) {
 201                 waitpid(pid, NULL, 0);
 202                 for (curr = envp; *curr; curr++) free(*curr);
 203                 free(envp);
 204                 return;
 205         } else if (pid == 0) {
 206                 /* close fd's? */
 207                 /* exec script */
 208                 execle(client_config.script, client_config.script,
 209                        name, NULL, envp);
 210                 bb_perror_msg("script %s failed", client_config.script);
 211                 exit(1);
 212         }
 213 }