| /* vi: set sw=4 ts=4: */ |
| /* |
| * options.c -- DHCP server option packet tools |
| * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001 |
| * |
| * Licensed under GPLv2, see file LICENSE in this tarball for details. |
| */ |
| |
| #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, result is not aligned). */ |
| uint8_t* FAST_FUNC get_option(struct dhcpMessage *packet, int code) |
| { |
| uint8_t *optionptr; |
| int len; |
| int rem; |
| int overload = 0; |
| enum { |
| FILE_FIELD101 = FILE_FIELD * 0x101, |
| SNAME_FIELD101 = SNAME_FIELD * 0x101, |
| }; |
| |
| /* option bytes: [code][len][data1][data2]..[dataLEN] */ |
| optionptr = packet->options; |
| rem = sizeof(packet->options); |
| while (1) { |
| if (rem <= 0) { |
| bb_error_msg("bogus packet, malformed option field"); |
| return NULL; |
| } |
| if (optionptr[OPT_CODE] == DHCP_PADDING) { |
| rem--; |
| optionptr++; |
| continue; |
| } |
| if (optionptr[OPT_CODE] == DHCP_END) { |
| if ((overload & FILE_FIELD101) == FILE_FIELD) { |
| /* can use packet->file, and didn't look at it yet */ |
| overload |= FILE_FIELD101; /* "we looked at it" */ |
| optionptr = packet->file; |
| rem = sizeof(packet->file); |
| continue; |
| } |
| if ((overload & SNAME_FIELD101) == SNAME_FIELD) { |
| /* can use packet->sname, and didn't look at it yet */ |
| overload |= SNAME_FIELD101; /* "we looked at it" */ |
| optionptr = packet->sname; |
| rem = sizeof(packet->sname); |
| continue; |
| } |
| return NULL; |
| } |
| len = 2 + optionptr[OPT_LEN]; |
| rem -= len; |
| if (rem < 0) |
| continue; /* complain and return NULL */ |
| |
| if (optionptr[OPT_CODE] == code) |
| return optionptr + OPT_DATA; |
| |
| if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) { |
| overload |= optionptr[OPT_DATA]; |
| /* fall through */ |
| } |
| optionptr += len; |
| } |
| 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 += optionptr[i + OPT_LEN] + 1; |
| i++; |
| } |
| return i; |
| } |
| |
| |
| /* add an option string to the options */ |
| /* option bytes: [code][len][data1][data2]..[dataLEN] */ |
| 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); |
| /* Assignment is unaligned! */ |
| move_to_unaligned32(&option[OPT_DATA], data); |
| return add_option_string(optionptr, option); |
| } |
| } |
| |
| bb_error_msg("cannot add option 0x%02x", code); |
| return 0; |
| } |
