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/* vi: set sw=4 ts=4: */
/* script.c
*
* Functions to call the DHCP client notification scripts
*
* Russ Dill <Russ.Dill@asu.edu> July 2001
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "common.h"
#include "options.h"
#include "dhcpd.h"
#include "dhcpc.h"
/* get a rough idea of how long an option will be (rounding up...) */
static const int max_option_length[] = {
[OPTION_IP] = sizeof("255.255.255.255 "),
[OPTION_IP_PAIR] = sizeof("255.255.255.255 ") * 2,
[OPTION_STRING] = 1,
[OPTION_BOOLEAN] = sizeof("yes "),
[OPTION_U8] = sizeof("255 "),
[OPTION_U16] = sizeof("65535 "),
[OPTION_S16] = sizeof("-32768 "),
[OPTION_U32] = sizeof("4294967295 "),
[OPTION_S32] = sizeof("-2147483684 "),
};
static inline int upper_length(int length, int opt_index)
{
return max_option_length[opt_index] *
(length / option_lengths[opt_index]);
}
static int sprintip(char *dest, char *pre, uint8_t *ip)
{
return sprintf(dest, "%s%d.%d.%d.%d", pre, ip[0], ip[1], ip[2], ip[3]);
}
/* really simple implementation, just count the bits */
static int mton(struct in_addr *mask)
{
int i;
unsigned long bits = ntohl(mask->s_addr);
/* too bad one can't check the carry bit, etc in c bit
* shifting */
for (i = 0; i < 32 && !((bits >> i) & 1); i++);
return 32 - i;
}
/* Fill dest with the text of option 'option'. */
static void fill_options(char *dest, uint8_t *option, struct dhcp_option *type_p)
{
int type, optlen;
uint16_t val_u16;
int16_t val_s16;
uint32_t val_u32;
int32_t val_s32;
int len = option[OPT_LEN - 2];
dest += sprintf(dest, "%s=", type_p->name);
type = type_p->flags & TYPE_MASK;
optlen = option_lengths[type];
for(;;) {
switch (type) {
case OPTION_IP_PAIR:
dest += sprintip(dest, "", option);
*(dest++) = '/';
option += 4;
optlen = 4;
case OPTION_IP: /* Works regardless of host byte order. */
dest += sprintip(dest, "", option);
break;
case OPTION_BOOLEAN:
dest += sprintf(dest, *option ? "yes" : "no");
break;
case OPTION_U8:
dest += sprintf(dest, "%u", *option);
break;
case OPTION_U16:
memcpy(&val_u16, option, 2);
dest += sprintf(dest, "%u", ntohs(val_u16));
break;
case OPTION_S16:
memcpy(&val_s16, option, 2);
dest += sprintf(dest, "%d", ntohs(val_s16));
break;
case OPTION_U32:
memcpy(&val_u32, option, 4);
dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
break;
case OPTION_S32:
memcpy(&val_s32, option, 4);
dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
break;
case OPTION_STRING:
memcpy(dest, option, len);
dest[len] = '\0';
return; /* Short circuit this case */
}
option += optlen;
len -= optlen;
if (len <= 0) break;
dest += sprintf(dest, " ");
}
}
/* put all the parameters into an environment */
static char **fill_envp(struct dhcpMessage *packet)
{
int num_options = 0;
int i, j;
char **envp;
uint8_t *temp;
struct in_addr subnet;
char over = 0;
if (packet == NULL)
num_options = 0;
else {
for (i = 0; dhcp_options[i].code; i++)
if (get_option(packet, dhcp_options[i].code)) {
num_options++;
if (dhcp_options[i].code == DHCP_SUBNET)
num_options++; /* for mton */
}
if (packet->siaddr) num_options++;
if ((temp = get_option(packet, DHCP_OPTION_OVER)))
over = *temp;
if (!(over & FILE_FIELD) && packet->file[0]) num_options++;
if (!(over & SNAME_FIELD) && packet->sname[0]) num_options++;
}
envp = xzalloc(sizeof(char *) * (num_options + 5));
j = 0;
envp[j++] = xasprintf("interface=%s", client_config.interface);
envp[j++] = xasprintf("PATH=%s",
getenv("PATH") ? : "/bin:/usr/bin:/sbin:/usr/sbin");
envp[j++] = xasprintf("HOME=%s", getenv("HOME") ? : "/");
if (packet == NULL) return envp;
envp[j] = xmalloc(sizeof("ip=255.255.255.255"));
sprintip(envp[j++], "ip=", (uint8_t *) &packet->yiaddr);
for (i = 0; dhcp_options[i].code; i++) {
if (!(temp = get_option(packet, dhcp_options[i].code)))
continue;
envp[j] = xmalloc(upper_length(temp[OPT_LEN - 2],
dhcp_options[i].flags & TYPE_MASK) + strlen(dhcp_options[i].name) + 2);
fill_options(envp[j++], temp, &dhcp_options[i]);
/* Fill in a subnet bits option for things like /24 */
if (dhcp_options[i].code == DHCP_SUBNET) {
memcpy(&subnet, temp, 4);
envp[j++] = xasprintf("mask=%d", mton(&subnet));
}
}
if (packet->siaddr) {
envp[j] = xmalloc(sizeof("siaddr=255.255.255.255"));
sprintip(envp[j++], "siaddr=", (uint8_t *) &packet->siaddr);
}
if (!(over & FILE_FIELD) && packet->file[0]) {
/* watch out for invalid packets */
packet->file[sizeof(packet->file) - 1] = '\0';
envp[j++] = xasprintf("boot_file=%s", packet->file);
}
if (!(over & SNAME_FIELD) && packet->sname[0]) {
/* watch out for invalid packets */
packet->sname[sizeof(packet->sname) - 1] = '\0';
envp[j++] = xasprintf("sname=%s", packet->sname);
}
return envp;
}
/* Call a script with a par file and env vars */
void udhcp_run_script(struct dhcpMessage *packet, const char *name)
{
int pid;
char **envp, **curr;
if (client_config.script == NULL)
return;
DEBUG("vfork'ing and execle'ing %s", client_config.script);
envp = fill_envp(packet);
/* call script */
pid = vfork();
if (pid) {
waitpid(pid, NULL, 0);
for (curr = envp; *curr; curr++) free(*curr);
free(envp);
return;
} else if (pid == 0) {
/* close fd's? */
/* exec script */
execle(client_config.script, client_config.script,
name, NULL, envp);
bb_perror_msg("script %s failed", client_config.script);
exit(1);
}
}
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