| /* vi: set sw=4 ts=4: */ |
| /* |
| * options.c -- DHCP server option packet tools |
| * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001 |
| */ |
| |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include "common.h" |
| #include "dhcpd.h" |
| #include "options.h" |
| #include "files.h" |
| |
| |
| /* supported options are easily added here */ |
| struct dhcp_option dhcp_options[] = { |
| /* name[10] flags code */ |
| {"subnet", OPTION_IP | OPTION_REQ, 0x01}, |
| {"timezone", OPTION_S32, 0x02}, |
| {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03}, |
| {"timesvr", OPTION_IP | OPTION_LIST, 0x04}, |
| {"namesvr", OPTION_IP | OPTION_LIST, 0x05}, |
| {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06}, |
| {"logsvr", OPTION_IP | OPTION_LIST, 0x07}, |
| {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08}, |
| {"lprsvr", OPTION_IP | OPTION_LIST, 0x09}, |
| {"hostname", OPTION_STRING | OPTION_REQ, 0x0c}, |
| {"bootsize", OPTION_U16, 0x0d}, |
| {"domain", OPTION_STRING | OPTION_REQ, 0x0f}, |
| {"swapsvr", OPTION_IP, 0x10}, |
| {"rootpath", OPTION_STRING, 0x11}, |
| {"ipttl", OPTION_U8, 0x17}, |
| {"mtu", OPTION_U16, 0x1a}, |
| {"broadcast", OPTION_IP | OPTION_REQ, 0x1c}, |
| {"nisdomain", OPTION_STRING | OPTION_REQ, 0x28}, |
| {"nissrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29}, |
| {"ntpsrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a}, |
| {"wins", OPTION_IP | OPTION_LIST, 0x2c}, |
| {"requestip", OPTION_IP, 0x32}, |
| {"lease", OPTION_U32, 0x33}, |
| {"dhcptype", OPTION_U8, 0x35}, |
| {"serverid", OPTION_IP, 0x36}, |
| {"message", OPTION_STRING, 0x38}, |
| {"tftp", OPTION_STRING, 0x42}, |
| {"bootfile", OPTION_STRING, 0x43}, |
| {"", 0x00, 0x00} |
| }; |
| |
| /* Lengths of the different option types */ |
| int option_lengths[] = { |
| [OPTION_IP] = 4, |
| [OPTION_IP_PAIR] = 8, |
| [OPTION_BOOLEAN] = 1, |
| [OPTION_STRING] = 1, |
| [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 *get_option(struct dhcpMessage *packet, int code) |
| { |
| int i, length; |
| uint8_t *optionptr; |
| int over = 0, done = 0, curr = OPTION_FIELD; |
| |
| optionptr = packet->options; |
| i = 0; |
| length = 308; |
| while (!done) { |
| if (i >= length) { |
| LOG(LOG_WARNING, "bogus packet, option fields too long."); |
| return NULL; |
| } |
| if (optionptr[i + OPT_CODE] == code) { |
| if (i + 1 + optionptr[i + OPT_LEN] >= length) { |
| LOG(LOG_WARNING, "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) { |
| LOG(LOG_WARNING, "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 = 128; |
| curr = FILE_FIELD; |
| } else if (curr == FILE_FIELD && over & SNAME_FIELD) { |
| optionptr = packet->sname; |
| i = 0; |
| length = 64; |
| curr = SNAME_FIELD; |
| } else done = 1; |
| break; |
| default: |
| i += optionptr[OPT_LEN + i] + 2; |
| } |
| } |
| return NULL; |
| } |
| |
| |
| /* return the position of the 'end' option (no bounds checking) */ |
| int 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 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 >= 308) { |
| LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]); |
| return 0; |
| } |
| DEBUG(LOG_INFO, "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 add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data) |
| { |
| 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 = option_lengths[dh->flags & TYPE_MASK]; |
| option[OPT_LEN] = len; |
| if (BB_BIG_ENDIAN) data <<= 8 * (4 - len); |
| /* This memcpy is for broken processors which can't |
| * handle a simple unaligned 32-bit assignment */ |
| memcpy(&option[OPT_DATA], &data, 4); |
| return add_option_string(optionptr, option); |
| } |
| } |
| |
| DEBUG(LOG_ERR, "Could not add option 0x%02x", code); |
| return 0; |
| } |