/* vi: set sw=4 ts=4: */ /* * options.c -- DHCP server option packet tools * Rewrite by Russ Dill July 2001 */ #include "common.h" #include "dhcpd.h" #include "options.h" /* Supported options are easily added here */ const struct dhcp_option dhcp_options[] = { /* flags code */ { OPTION_IP | OPTION_REQ, 0x01 }, /* DHCP_SUBNET */ { OPTION_S32 , 0x02 }, /* DHCP_TIME_OFFSET */ { OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03 }, /* DHCP_ROUTER */ { OPTION_IP | OPTION_LIST , 0x04 }, /* DHCP_TIME_SERVER */ { OPTION_IP | OPTION_LIST , 0x05 }, /* DHCP_NAME_SERVER */ { OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06 }, /* DHCP_DNS_SERVER */ { OPTION_IP | OPTION_LIST , 0x07 }, /* DHCP_LOG_SERVER */ { OPTION_IP | OPTION_LIST , 0x08 }, /* DHCP_COOKIE_SERVER */ { OPTION_IP | OPTION_LIST , 0x09 }, /* DHCP_LPR_SERVER */ { OPTION_STRING | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */ { OPTION_U16 , 0x0d }, /* DHCP_BOOT_SIZE */ { OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */ { OPTION_IP , 0x10 }, /* DHCP_SWAP_SERVER */ { OPTION_STRING , 0x11 }, /* DHCP_ROOT_PATH */ { OPTION_U8 , 0x17 }, /* DHCP_IP_TTL */ { OPTION_U16 , 0x1a }, /* DHCP_MTU */ { OPTION_IP | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST */ { OPTION_STRING , 0x28 }, /* nisdomain */ { OPTION_IP | OPTION_LIST , 0x29 }, /* nissrv */ { OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER */ { OPTION_IP | OPTION_LIST , 0x2c }, /* DHCP_WINS_SERVER */ { OPTION_IP , 0x32 }, /* DHCP_REQUESTED_IP */ { OPTION_U32 , 0x33 }, /* DHCP_LEASE_TIME */ { OPTION_U8 , 0x35 }, /* dhcptype */ { OPTION_IP , 0x36 }, /* DHCP_SERVER_ID */ { OPTION_STRING , 0x38 }, /* DHCP_MESSAGE */ { OPTION_STRING , 0x3C }, /* DHCP_VENDOR */ { OPTION_STRING , 0x3D }, /* DHCP_CLIENT_ID */ { OPTION_STRING , 0x42 }, /* tftp */ { OPTION_STRING , 0x43 }, /* bootfile */ { OPTION_STRING , 0x4D }, /* userclass */ #if ENABLE_FEATURE_UDHCP_RFC3397 { OPTION_STR1035 | OPTION_LIST , 0x77 }, /* search */ #endif /* MSIE's "Web Proxy Autodiscovery Protocol" support */ { OPTION_STRING , 0xfc }, /* wpad */ /* Options below have no match in dhcp_option_strings[], * are not passed to dhcpc scripts, and cannot be specified * with "option XXX YYY" syntax in dhcpd config file. */ { OPTION_U16 , 0x39 }, /* DHCP_MAX_SIZE */ { } /* zeroed terminating entry */ }; /* Used for converting options from incoming packets to env variables * for udhcpc stript */ /* Must match dhcp_options[] order */ const char dhcp_option_strings[] ALIGN1 = "subnet" "\0" /* DHCP_SUBNET */ "timezone" "\0" /* DHCP_TIME_OFFSET */ "router" "\0" /* DHCP_ROUTER */ "timesrv" "\0" /* DHCP_TIME_SERVER */ "namesrv" "\0" /* DHCP_NAME_SERVER */ "dns" "\0" /* DHCP_DNS_SERVER */ "logsrv" "\0" /* DHCP_LOG_SERVER */ "cookiesrv" "\0" /* DHCP_COOKIE_SERVER */ "lprsrv" "\0" /* DHCP_LPR_SERVER */ "hostname" "\0" /* DHCP_HOST_NAME */ "bootsize" "\0" /* DHCP_BOOT_SIZE */ "domain" "\0" /* DHCP_DOMAIN_NAME */ "swapsrv" "\0" /* DHCP_SWAP_SERVER */ "rootpath" "\0" /* DHCP_ROOT_PATH */ "ipttl" "\0" /* DHCP_IP_TTL */ "mtu" "\0" /* DHCP_MTU */ "broadcast" "\0" /* DHCP_BROADCAST */ "nisdomain" "\0" /* */ "nissrv" "\0" /* */ "ntpsrv" "\0" /* DHCP_NTP_SERVER */ "wins" "\0" /* DHCP_WINS_SERVER */ "requestip" "\0" /* DHCP_REQUESTED_IP */ "lease" "\0" /* DHCP_LEASE_TIME */ "dhcptype" "\0" /* */ "serverid" "\0" /* DHCP_SERVER_ID */ "message" "\0" /* DHCP_MESSAGE */ "vendorclass" "\0" /* DHCP_VENDOR */ "clientid" "\0" /* DHCP_CLIENT_ID */ "tftp" "\0" "bootfile" "\0" "userclass" "\0" #if ENABLE_FEATURE_UDHCP_RFC3397 "search" "\0" #endif /* MSIE's "Web Proxy Autodiscovery Protocol" support */ "wpad" "\0" ; /* Lengths of the different option types */ const uint8_t dhcp_option_lengths[] ALIGN1 = { [OPTION_IP] = 4, [OPTION_IP_PAIR] = 8, [OPTION_BOOLEAN] = 1, [OPTION_STRING] = 1, #if ENABLE_FEATURE_UDHCP_RFC3397 [OPTION_STR1035] = 1, #endif [OPTION_U8] = 1, [OPTION_U16] = 2, [OPTION_S16] = 2, [OPTION_U32] = 4, [OPTION_S32] = 4 }; /* get an option with bounds checking (warning, not aligned). */ uint8_t* FAST_FUNC get_option(struct dhcpMessage *packet, int code) { int i, length; uint8_t *optionptr; int over = 0; int curr = OPTION_FIELD; optionptr = packet->options; i = 0; length = sizeof(packet->options); while (1) { if (i >= length) { bb_error_msg("bogus packet, option fields too long"); return NULL; } if (optionptr[i + OPT_CODE] == code) { if (i + 1 + optionptr[i + OPT_LEN] >= length) { bb_error_msg("bogus packet, option fields too long"); return NULL; } return optionptr + i + 2; } switch (optionptr[i + OPT_CODE]) { case DHCP_PADDING: i++; break; case DHCP_OPTION_OVER: if (i + 1 + optionptr[i + OPT_LEN] >= length) { bb_error_msg("bogus packet, option fields too long"); return NULL; } over = optionptr[i + 3]; i += optionptr[OPT_LEN] + 2; break; case DHCP_END: if (curr == OPTION_FIELD && (over & FILE_FIELD)) { optionptr = packet->file; i = 0; length = sizeof(packet->file); curr = FILE_FIELD; } else if (curr == FILE_FIELD && (over & SNAME_FIELD)) { optionptr = packet->sname; i = 0; length = sizeof(packet->sname); curr = SNAME_FIELD; } else return NULL; break; default: i += optionptr[OPT_LEN + i] + 2; } } return NULL; } /* return the position of the 'end' option (no bounds checking) */ int FAST_FUNC end_option(uint8_t *optionptr) { int i = 0; while (optionptr[i] != DHCP_END) { if (optionptr[i] == DHCP_PADDING) i++; else i += optionptr[i + OPT_LEN] + 2; } return i; } /* add an option string to the options (an option string contains an option code, * length, then data) */ int FAST_FUNC add_option_string(uint8_t *optionptr, uint8_t *string) { int end = end_option(optionptr); /* end position + string length + option code/length + end option */ if (end + string[OPT_LEN] + 2 + 1 >= DHCP_OPTIONS_BUFSIZE) { bb_error_msg("option 0x%02x did not fit into the packet", string[OPT_CODE]); return 0; } DEBUG("adding option 0x%02x", string[OPT_CODE]); memcpy(optionptr + end, string, string[OPT_LEN] + 2); optionptr[end + string[OPT_LEN] + 2] = DHCP_END; return string[OPT_LEN] + 2; } /* add a one to four byte option to a packet */ int FAST_FUNC add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data) { const struct dhcp_option *dh; for (dh = dhcp_options; dh->code; dh++) { if (dh->code == code) { uint8_t option[6], len; option[OPT_CODE] = code; len = dhcp_option_lengths[dh->flags & TYPE_MASK]; option[OPT_LEN] = len; if (BB_BIG_ENDIAN) data <<= 8 * (4 - len); /* This memcpy is for processors which can't * handle a simple unaligned 32-bit assignment */ memcpy(&option[OPT_DATA], &data, 4); return add_option_string(optionptr, option); } } bb_error_msg("cannot add option 0x%02x", code); return 0; }