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 <string.h>
  12 #include <unistd.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <sys/socket.h>
  16 #include <netinet/in.h>
  17 #include <arpa/inet.h>
  18 #include <sys/types.h>
  19 #include <sys/wait.h>
  20
  21 #include "common.h"
  22 #include "options.h"
  23 #include "dhcpd.h"
  24 #include "dhcpc.h"
  25
  26 /* get a rough idea of how long an option will be (rounding up...) */
  27 static const int max_option_length[] = {
  28         [OPTION_IP] =           sizeof("255.255.255.255 "),
  29         [OPTION_IP_PAIR] =      sizeof("255.255.255.255 ") * 2,
  30         [OPTION_STRING] =       1,
  31         [OPTION_BOOLEAN] =      sizeof("yes "),
  32         [OPTION_U8] =           sizeof("255 "),
  33         [OPTION_U16] =          sizeof("65535 "),
  34         [OPTION_S16] =          sizeof("-32768 "),
  35         [OPTION_U32] =          sizeof("4294967295 "),
  36         [OPTION_S32] =          sizeof("-2147483684 "),
  37 };
  38
  39
  40 static inline int upper_length(int length, int opt_index)
  41 {
  42         return max_option_length[opt_index] *
  43                 (length / option_lengths[opt_index]);
  44 }
  45
  46
  47 static int sprintip(char *dest, char *pre, uint8_t *ip)
  48 {
  49         return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
  50 }
  51
  52
  53 /* really simple implementation, just count the bits */
  54 static int mton(struct in_addr *mask)
  55 {
  56         int i;
  57         unsigned long bits = ntohl(mask->s_addr);
  58         /* too bad one can't check the carry bit, etc in c bit
  59          * shifting */
  60         for (i = 0; i < 32 && !((bits >> i) & 1); i++);
  61         return 32 - i;
  62 }
  63
  64
  65 /* Fill dest with the text of option 'option'. */
  66 static void fill_options(char *dest, uint8_t *option, struct dhcp_option *type_p)
  67 {
  68         int type, optlen;
  69         uint16_t val_u16;
  70         int16_t val_s16;
  71         uint32_t val_u32;
  72         int32_t val_s32;
  73         int len = option[OPT_LEN - 2];
  74
  75         dest += sprintf(dest, "%s=", type_p->name);
  76
  77         type = type_p->flags & TYPE_MASK;
  78         optlen = option_lengths[type];
  79         for(;;) {
  80                 switch (type) {
  81                 case OPTION_IP_PAIR:
  82                         dest += sprintip(dest, "", option);
  83                         *(dest++) = '/';
  84                         option += 4;
  85                         optlen = 4;
  86                 case OPTION_IP: /* Works regardless of host byte order. */
  87                         dest += sprintip(dest, "", option);
  88                         break;
  89                 case OPTION_BOOLEAN:
  90                         dest += sprintf(dest, *option ? "yes" : "no");
  91                         break;
  92                 case OPTION_U8:
  93                         dest += sprintf(dest, "%u", *option);
  94                         break;
  95                 case OPTION_U16:
  96                         memcpy(&val_u16, option, 2);
  97                         dest += sprintf(dest, "%u", ntohs(val_u16));
  98                         break;
  99                 case OPTION_S16:
 100                         memcpy(&val_s16, option, 2);
 101                         dest += sprintf(dest, "%d", ntohs(val_s16));
 102                         break;
 103                 case OPTION_U32:
 104                         memcpy(&val_u32, option, 4);
 105                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 106                         break;
 107                 case OPTION_S32:
 108                         memcpy(&val_s32, option, 4);
 109                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 110                         break;
 111                 case OPTION_STRING:
 112                         memcpy(dest, option, len);
 113                         dest[len] = '\0';
 114                         return;  /* Short circuit this case */
 115                 }
 116                 option += optlen;
 117                 len -= optlen;
 118                 if (len <= 0) break;
 119                 dest += sprintf(dest, " ");
 120         }
 121 }
 122
 123
 124 /* put all the parameters into an environment */
 125 static char **fill_envp(struct dhcpMessage *packet)
 126 {
 127         int num_options = 0;
 128         int i, j;
 129         char **envp;
 130         uint8_t *temp;
 131         struct in_addr subnet;
 132         char over = 0;
 133
 134         if (packet == NULL)
 135                 num_options = 0;
 136         else {
 137                 for (i = 0; dhcp_options[i].code; i++)
 138                         if (get_option(packet, dhcp_options[i].code)) {
 139                                 num_options++;
 140                                 if (dhcp_options[i].code == DHCP_SUBNET)
 141                                         num_options++; /* for mton */
 142                         }
 143                 if (packet->siaddr) num_options++;
 144                 if ((temp = get_option(packet, DHCP_OPTION_OVER)))
 145                         over = *temp;
 146                 if (!(over & FILE_FIELD) && packet->file[0]) num_options++;
 147                 if (!(over & SNAME_FIELD) && packet->sname[0]) num_options++;
 148         }
 149
 150         envp = xzalloc(sizeof(char *) * (num_options + 5));
 151         j = 0;
 152         envp[j++] = xasprintf("interface=%s", client_config.interface);
 153         envp[j++] = xasprintf("PATH=%s",
 154                 getenv("PATH") ? : "/bin:/usr/bin:/sbin:/usr/sbin");
 155         envp[j++] = xasprintf("HOME=%s", getenv("HOME") ? : "/");
 156
 157         if (packet == NULL) return envp;
 158
 159         envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
 160         sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
 161
 162
 163         for (i = 0; dhcp_options[i].code; i++) {
 164                 if (!(temp = get_option(packet, dhcp_options[i].code)))
 165                         continue;
 166                 envp[j] = xmalloc(upper_length(temp[OPT_LEN - 2],
 167                         dhcp_options[i].flags & TYPE_MASK) + strlen(dhcp_options[i].name) + 2);
 168                 fill_options(envp[j++], temp, &dhcp_options[i]);
 169
 170                 /* Fill in a subnet bits option for things like /24 */
 171                 if (dhcp_options[i].code == DHCP_SUBNET) {
 172                         memcpy(&subnet, temp, 4);
 173                         envp[j++] = xasprintf("mask=%d", mton(&subnet));
 174                 }
 175         }
 176         if (packet->siaddr) {
 177                 envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
 178                 sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
 179         }
 180         if (!(over & FILE_FIELD) && packet->file[0]) {
 181                 /* watch out for invalid packets */
 182                 packet->file[sizeof(packet->file) - 1] = '\0';
 183                 envp[j++] = xasprintf("boot_file=%s", packet->file);
 184         }
 185         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 186                 /* watch out for invalid packets */
 187                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 188                 envp[j++] = xasprintf("sname=%s", packet->sname);
 189         }
 190         return envp;
 191 }
 192
 193
 194 /* Call a script with a par file and env vars */
 195 void udhcp_run_script(struct dhcpMessage *packet, const char *name)
 196 {
 197         int pid;
 198         char **envp, **curr;
 199
 200         if (client_config.script == NULL)
 201                 return;
 202
 203         DEBUG("vfork'ing and execle'ing %s", client_config.script);
 204
 205         envp = fill_envp(packet);
 206         /* call script */
 207         pid = vfork();
 208         if (pid) {
 209                 waitpid(pid, NULL, 0);
 210                 for (curr = envp; *curr; curr++) free(*curr);
 211                 free(envp);
 212                 return;
 213         } else if (pid == 0) {
 214                 /* close fd's? */
 215
 216                 /* exec script */
 217                 execle(client_config.script, client_config.script,
 218                        name, NULL, envp);
 219                 bb_perror_msg("script %s failed", client_config.script);
 220                 exit(1);
 221         }
 222 }