source: MondoRescue/branches/stable/mindi-busybox/networking/udhcp/script.c@ 1770

/* 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 "common.h"
#include "dhcpc.h"
#include "options.h"


/* get a rough idea of how long an option will be (rounding up...) */
static const uint8_t max_option_length[] = {
    [OPTION_IP] =       sizeof("255.255.255.255 "),
    [OPTION_IP_PAIR] =  sizeof("255.255.255.255 ") * 2,
    [OPTION_STRING] =   1,
#if ENABLE_FEATURE_RFC3397
    [OPTION_STR1035] =  1,
#endif
    [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, const char *pre, const 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;
}


/* Allocate and fill with the text of option 'option'. */
static char *alloc_fill_opts(uint8_t *option, const struct dhcp_option *type_p)
{
    int len, type, optlen;
    uint16_t val_u16;
    int16_t val_s16;
    uint32_t val_u32;
    int32_t val_s32;
    char *dest, *ret;

    len = option[OPT_LEN - 2];
    type = type_p->flags & TYPE_MASK;
    optlen = option_lengths[type];

    dest = ret = xmalloc(upper_length(len, type) + strlen(type_p->name) + 2);
    dest += sprintf(ret, "%s=", type_p->name);

    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 ret;  /* Short circuit this case */
#if ENABLE_FEATURE_RFC3397
        case OPTION_STR1035:
            /* unpack option into dest; use ret for prefix (i.e., "optname=") */
            dest = dname_dec(option, len, ret);
            free(ret);
            return dest;
#endif
        }
        option += optlen;
        len -= optlen;
        if (len <= 0) break;
        dest += sprintf(dest, " ");
    }
    return ret;
}


/* put all the parameters into an environment */
static char **fill_envp(struct dhcpMessage *packet)
{
    int num_options = 0;
    int i, j;
    char **envp;
    char *var;
    uint8_t *temp;
    struct in_addr subnet;
    char over = 0;

    if (packet) {
        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++;
        temp = get_option(packet, DHCP_OPTION_OVER);
        if (temp)
            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);
    var = getenv("PATH");
    if (var)
        envp[j++] = xasprintf("PATH=%s", var);
    var = getenv("HOME");
    if (var)
        envp[j++] = xasprintf("HOME=%s", var);

    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++) {
        temp = get_option(packet, dhcp_options[i].code);
        if (!temp)
            continue;
        envp[j++] = alloc_fill_opts(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 */
// can we use wait4pid(spawn(...)) here?
    pid = vfork();
    if (pid < 0) return;
    if (pid == 0) {
        /* close fd's? */
        /* exec script */
        execle(client_config.script, client_config.script,
               name, NULL, envp);
        bb_perror_msg_and_die("script %s failed", client_config.script);
    }
    waitpid(pid, NULL, 0);
    for (curr = envp; *curr; curr++)
        free(*curr);
    free(envp);
}