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_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 / 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(struct in_addr *mask)
  48 {
  49         int i;
  50         unsigned long bits = ntohl(mask->s_addr);
  51         /* too bad one can't check the carry bit, etc in c bit
  52          * shifting */
  53         for (i = 0; i < 32 && !((bits >> i) & 1); i++);
  54         return 32 - i;
  55 }
  56
  57
  58 /* Allocate and fill with the text of option 'option'. */
  59 static char *alloc_fill_opts(uint8_t *option, const struct dhcp_option *type_p)
  60 {
  61         int len, type, optlen;
  62         uint16_t val_u16;
  63         int16_t val_s16;
  64         uint32_t val_u32;
  65         int32_t val_s32;
  66         char *dest, *ret;
  67
  68         len = option[OPT_LEN - 2];
  69         type = type_p->flags & TYPE_MASK;
  70         optlen = option_lengths[type];
  71
  72         dest = ret = xmalloc(upper_length(len, type) + strlen(type_p->name) + 2);
  73         dest += sprintf(ret, "%s=", type_p->name);
  74
  75         for (;;) {
  76                 switch (type) {
  77                 case OPTION_IP_PAIR:
  78                         dest += sprintip(dest, "", option);
  79                         *dest++ = '/';
  80                         option += 4;
  81                         optlen = 4;
  82                 case OPTION_IP: /* Works regardless of host byte order. */
  83                         dest += sprintip(dest, "", option);
  84                         break;
  85                 case OPTION_BOOLEAN:
  86                         dest += sprintf(dest, *option ? "yes" : "no");
  87                         break;
  88                 case OPTION_U8:
  89                         dest += sprintf(dest, "%u", *option);
  90                         break;
  91                 case OPTION_U16:
  92                         memcpy(&val_u16, option, 2);
  93                         dest += sprintf(dest, "%u", ntohs(val_u16));
  94                         break;
  95                 case OPTION_S16:
  96                         memcpy(&val_s16, option, 2);
  97                         dest += sprintf(dest, "%d", ntohs(val_s16));
  98                         break;
  99                 case OPTION_U32:
 100                         memcpy(&val_u32, option, 4);
 101                         dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
 102                         break;
 103                 case OPTION_S32:
 104                         memcpy(&val_s32, option, 4);
 105                         dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
 106                         break;
 107                 case OPTION_STRING:
 108                         memcpy(dest, option, len);
 109                         dest[len] = '\0';
 110                         return ret;      /* Short circuit this case */
 111 #if ENABLE_FEATURE_RFC3397
 112                 case OPTION_STR1035:
 113                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
 114                         dest = dname_dec(option, len, ret);
 115                         free(ret);
 116                         return dest;
 117 #endif
 118                 }
 119                 option += optlen;
 120                 len -= optlen;
 121                 if (len <= 0) break;
 122                 dest += sprintf(dest, " ");
 123         }
 124         return ret;
 125 }
 126
 127
 128 /* put all the parameters into an environment */
 129 static char **fill_envp(struct dhcpMessage *packet)
 130 {
 131         int num_options = 0;
 132         int i, j;
 133         char **envp;
 134         char *var;
 135         uint8_t *temp;
 136         struct in_addr subnet;
 137         char over = 0;
 138
 139         if (packet) {
 140                 for (i = 0; dhcp_options[i].code; i++) {
 141                         if (get_option(packet, dhcp_options[i].code)) {
 142                                 num_options++;
 143                                 if (dhcp_options[i].code == DHCP_SUBNET)
 144                                         num_options++; /* for mton */
 145                         }
 146                 }
 147                 if (packet->siaddr)
 148                         num_options++;
 149                 temp = get_option(packet, DHCP_OPTION_OVER);
 150                 if (temp)
 151                         over = *temp;
 152                 if (!(over & FILE_FIELD) && packet->file[0])
 153                         num_options++;
 154                 if (!(over & SNAME_FIELD) && packet->sname[0])
 155                         num_options++;
 156         }
 157
 158         envp = xzalloc(sizeof(char *) * (num_options + 5));
 159         j = 0;
 160         envp[j++] = xasprintf("interface=%s", client_config.interface);
 161         var = getenv("PATH");
 162         if (var)
 163                 envp[j++] = xasprintf("PATH=%s", var);
 164         var = getenv("HOME");
 165         if (var)
 166                 envp[j++] = xasprintf("HOME=%s", var);
 167
 168         if (packet == NULL)
 169                 return envp;
 170
 171         envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
 172         sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
 173
 174         for (i = 0; dhcp_options[i].code; i++) {
 175                 temp = get_option(packet, dhcp_options[i].code);
 176                 if (!temp)
 177                         continue;
 178                 envp[j++] = alloc_fill_opts(temp, &dhcp_options[i]);
 179
 180                 /* Fill in a subnet bits option for things like /24 */
 181                 if (dhcp_options[i].code == DHCP_SUBNET) {
 182                         memcpy(&subnet, temp, 4);
 183                         envp[j++] = xasprintf("mask=%d", mton(&subnet));
 184                 }
 185         }
 186         if (packet->siaddr) {
 187                 envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
 188                 sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
 189         }
 190         if (!(over & FILE_FIELD) && packet->file[0]) {
 191                 /* watch out for invalid packets */
 192                 packet->file[sizeof(packet->file) - 1] = '\0';
 193                 envp[j++] = xasprintf("boot_file=%s", packet->file);
 194         }
 195         if (!(over & SNAME_FIELD) && packet->sname[0]) {
 196                 /* watch out for invalid packets */
 197                 packet->sname[sizeof(packet->sname) - 1] = '\0';
 198                 envp[j++] = xasprintf("sname=%s", packet->sname);
 199         }
 200         return envp;
 201 }
 202
 203
 204 /* Call a script with a par file and env vars */
 205 void udhcp_run_script(struct dhcpMessage *packet, const char *name)
 206 {
 207         int pid;
 208         char **envp, **curr;
 209
 210         if (client_config.script == NULL)
 211                 return;
 212
 213         DEBUG("vfork'ing and execle'ing %s", client_config.script);
 214
 215         envp = fill_envp(packet);
 216
 217         /* call script */
 218 // can we use wait4pid(spawn(...)) here?
 219         pid = vfork();
 220         if (pid < 0) return;
 221         if (pid == 0) {
 222                 /* close fd's? */
 223                 /* exec script */
 224                 execle(client_config.script, client_config.script,
 225                        name, NULL, envp);
 226                 bb_perror_msg_and_die("script %s failed", client_config.script);
 227         }
 228         waitpid(pid, NULL, 0);
 229         for (curr = envp; *curr; curr++)
 230                 free(*curr);
 231         free(envp);
 232 }