[821] | 1 | /*
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| 2 | * options.c -- DHCP server option packet tools
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| 3 | * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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| 4 | */
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| 5 |
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| 6 | #include <stdlib.h>
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| 7 | #include <string.h>
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| 8 |
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| 9 | #include "common.h"
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| 10 | #include "dhcpd.h"
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| 11 | #include "options.h"
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| 12 | #include "files.h"
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| 13 |
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| 14 |
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| 15 | /* supported options are easily added here */
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| 16 | struct dhcp_option dhcp_options[] = {
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| 17 | /* name[10] flags code */
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| 18 | {"subnet", OPTION_IP | OPTION_REQ, 0x01},
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| 19 | {"timezone", OPTION_S32, 0x02},
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| 20 | {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03},
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| 21 | {"timesvr", OPTION_IP | OPTION_LIST, 0x04},
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| 22 | {"namesvr", OPTION_IP | OPTION_LIST, 0x05},
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| 23 | {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06},
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| 24 | {"logsvr", OPTION_IP | OPTION_LIST, 0x07},
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| 25 | {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08},
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| 26 | {"lprsvr", OPTION_IP | OPTION_LIST, 0x09},
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| 27 | {"hostname", OPTION_STRING | OPTION_REQ, 0x0c},
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| 28 | {"bootsize", OPTION_U16, 0x0d},
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| 29 | {"domain", OPTION_STRING | OPTION_REQ, 0x0f},
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| 30 | {"swapsvr", OPTION_IP, 0x10},
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| 31 | {"rootpath", OPTION_STRING, 0x11},
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| 32 | {"ipttl", OPTION_U8, 0x17},
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| 33 | {"mtu", OPTION_U16, 0x1a},
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| 34 | {"broadcast", OPTION_IP | OPTION_REQ, 0x1c},
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| 35 | {"nisdomain", OPTION_STRING | OPTION_REQ, 0x28},
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| 36 | {"nissrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29},
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| 37 | {"ntpsrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a},
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| 38 | {"wins", OPTION_IP | OPTION_LIST, 0x2c},
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| 39 | {"requestip", OPTION_IP, 0x32},
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| 40 | {"lease", OPTION_U32, 0x33},
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| 41 | {"dhcptype", OPTION_U8, 0x35},
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| 42 | {"serverid", OPTION_IP, 0x36},
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| 43 | {"message", OPTION_STRING, 0x38},
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| 44 | {"tftp", OPTION_STRING, 0x42},
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| 45 | {"bootfile", OPTION_STRING, 0x43},
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| 46 | {"", 0x00, 0x00}
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| 47 | };
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| 48 |
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| 49 | /* Lengths of the different option types */
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| 50 | int option_lengths[] = {
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| 51 | [OPTION_IP] = 4,
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| 52 | [OPTION_IP_PAIR] = 8,
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| 53 | [OPTION_BOOLEAN] = 1,
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| 54 | [OPTION_STRING] = 1,
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| 55 | [OPTION_U8] = 1,
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| 56 | [OPTION_U16] = 2,
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| 57 | [OPTION_S16] = 2,
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| 58 | [OPTION_U32] = 4,
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| 59 | [OPTION_S32] = 4
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| 60 | };
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| 61 |
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| 62 |
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| 63 | /* get an option with bounds checking (warning, not aligned). */
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| 64 | uint8_t *get_option(struct dhcpMessage *packet, int code)
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| 65 | {
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| 66 | int i, length;
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| 67 | uint8_t *optionptr;
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| 68 | int over = 0, done = 0, curr = OPTION_FIELD;
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| 69 |
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| 70 | optionptr = packet->options;
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| 71 | i = 0;
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| 72 | length = 308;
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| 73 | while (!done) {
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| 74 | if (i >= length) {
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| 75 | LOG(LOG_WARNING, "bogus packet, option fields too long.");
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| 76 | return NULL;
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| 77 | }
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| 78 | if (optionptr[i + OPT_CODE] == code) {
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| 79 | if (i + 1 + optionptr[i + OPT_LEN] >= length) {
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| 80 | LOG(LOG_WARNING, "bogus packet, option fields too long.");
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| 81 | return NULL;
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| 82 | }
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| 83 | return optionptr + i + 2;
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| 84 | }
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| 85 | switch (optionptr[i + OPT_CODE]) {
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| 86 | case DHCP_PADDING:
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| 87 | i++;
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| 88 | break;
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| 89 | case DHCP_OPTION_OVER:
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| 90 | if (i + 1 + optionptr[i + OPT_LEN] >= length) {
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| 91 | LOG(LOG_WARNING, "bogus packet, option fields too long.");
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| 92 | return NULL;
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| 93 | }
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| 94 | over = optionptr[i + 3];
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| 95 | i += optionptr[OPT_LEN] + 2;
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| 96 | break;
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| 97 | case DHCP_END:
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| 98 | if (curr == OPTION_FIELD && over & FILE_FIELD) {
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| 99 | optionptr = packet->file;
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| 100 | i = 0;
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| 101 | length = 128;
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| 102 | curr = FILE_FIELD;
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| 103 | } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
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| 104 | optionptr = packet->sname;
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| 105 | i = 0;
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| 106 | length = 64;
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| 107 | curr = SNAME_FIELD;
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| 108 | } else done = 1;
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| 109 | break;
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| 110 | default:
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| 111 | i += optionptr[OPT_LEN + i] + 2;
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| 112 | }
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| 113 | }
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| 114 | return NULL;
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| 115 | }
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| 116 |
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| 117 |
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| 118 | /* return the position of the 'end' option (no bounds checking) */
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| 119 | int end_option(uint8_t *optionptr)
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| 120 | {
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| 121 | int i = 0;
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| 122 |
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| 123 | while (optionptr[i] != DHCP_END) {
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| 124 | if (optionptr[i] == DHCP_PADDING) i++;
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| 125 | else i += optionptr[i + OPT_LEN] + 2;
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| 126 | }
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| 127 | return i;
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| 128 | }
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| 129 |
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| 130 |
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| 131 | /* add an option string to the options (an option string contains an option code,
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| 132 | * length, then data) */
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| 133 | int add_option_string(uint8_t *optionptr, uint8_t *string)
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| 134 | {
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| 135 | int end = end_option(optionptr);
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| 136 |
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| 137 | /* end position + string length + option code/length + end option */
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| 138 | if (end + string[OPT_LEN] + 2 + 1 >= 308) {
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| 139 | LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]);
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| 140 | return 0;
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| 141 | }
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| 142 | DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]);
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| 143 | memcpy(optionptr + end, string, string[OPT_LEN] + 2);
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| 144 | optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
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| 145 | return string[OPT_LEN] + 2;
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| 146 | }
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| 147 |
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| 148 |
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| 149 | /* add a one to four byte option to a packet */
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| 150 | int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
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| 151 | {
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| 152 | struct dhcp_option *dh;
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| 153 |
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| 154 | for (dh=dhcp_options; dh->code; dh++) {
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| 155 | if (dh->code == code) {
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| 156 | uint8_t option[6], len;
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| 157 |
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| 158 | option[OPT_CODE] = code;
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| 159 | len = option_lengths[dh->flags & TYPE_MASK];
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| 160 | option[OPT_LEN] = len;
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| 161 | if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
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| 162 | /* This memcpy is for broken processors which can't
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| 163 | * handle a simple unaligned 32-bit assignment */
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| 164 | memcpy(&option[OPT_DATA], &data, 4);
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| 165 | return add_option_string(optionptr, option);
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| 166 | }
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| 167 | }
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| 168 |
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| 169 | DEBUG(LOG_ERR, "Could not add option 0x%02x", code);
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| 170 | return 0;
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| 171 | }
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