/* vi: set sw=4 ts=4: */ /* script.c * * Functions to call the DHCP client notification scripts * * Russ Dill July 2001 * * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. */ #include "common.h" #include "dhcpd.h" #include "dhcpc.h" #include "options.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, 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; } /* Fill dest with the text of option 'option'. */ static void fill_options(char *dest, uint8_t *option, const 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++) { temp = get_option(packet, dhcp_options[i].code); if (!temp) 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); } }