diff options
Diffstat (limited to 'networking/udhcp/options.c')
| -rw-r--r-- | networking/udhcp/options.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/networking/udhcp/options.c b/networking/udhcp/options.c new file mode 100644 index 0000000..d394b4c --- /dev/null +++ b/networking/udhcp/options.c @@ -0,0 +1,172 @@ +/* + * 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 (__BYTE_ORDER == __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; +} |