[1765] | 1 | /* vi: set sw=4 ts=4: */
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[821] | 2 | /*
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| 3 | * options.c -- DHCP server option packet tools
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| 4 | * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
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| 5 | */
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| 6 |
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| 7 | #include "common.h"
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| 8 | #include "dhcpd.h"
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| 9 | #include "options.h"
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| 10 |
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| 11 |
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| 12 | /* supported options are easily added here */
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[1765] | 13 | const struct dhcp_option dhcp_options[] = {
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| 14 | /* name[12] flags code */
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| 15 | {"subnet", OPTION_IP | OPTION_REQ, 0x01},
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| 16 | {"timezone", OPTION_S32, 0x02},
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| 17 | {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03},
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| 18 | {"timesvr", OPTION_IP | OPTION_LIST, 0x04},
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| 19 | {"namesvr", OPTION_IP | OPTION_LIST, 0x05},
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| 20 | {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06},
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| 21 | {"logsvr", OPTION_IP | OPTION_LIST, 0x07},
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| 22 | {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08},
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| 23 | {"lprsvr", OPTION_IP | OPTION_LIST, 0x09},
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| 24 | {"hostname", OPTION_STRING | OPTION_REQ, 0x0c},
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| 25 | {"bootsize", OPTION_U16, 0x0d},
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| 26 | {"domain", OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x0f},
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| 27 | {"swapsvr", OPTION_IP, 0x10},
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| 28 | {"rootpath", OPTION_STRING, 0x11},
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| 29 | {"ipttl", OPTION_U8, 0x17},
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| 30 | {"mtu", OPTION_U16, 0x1a},
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| 31 | {"broadcast", OPTION_IP | OPTION_REQ, 0x1c},
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| 32 | {"nisdomain", OPTION_STRING | OPTION_REQ, 0x28},
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| 33 | {"nissrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29},
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| 34 | {"ntpsrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a},
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| 35 | {"wins", OPTION_IP | OPTION_LIST, 0x2c},
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| 36 | {"requestip", OPTION_IP, 0x32},
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| 37 | {"lease", OPTION_U32, 0x33},
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| 38 | {"dhcptype", OPTION_U8, 0x35},
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| 39 | {"serverid", OPTION_IP, 0x36},
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| 40 | {"message", OPTION_STRING, 0x38},
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| 41 | {"vendorclass", OPTION_STRING, 0x3C},
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| 42 | {"clientid", OPTION_STRING, 0x3D},
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| 43 | {"tftp", OPTION_STRING, 0x42},
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| 44 | {"bootfile", OPTION_STRING, 0x43},
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| 45 | {"userclass", OPTION_STRING, 0x4D},
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| 46 | #if ENABLE_FEATURE_RFC3397
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| 47 | {"search", OPTION_STR1035 | OPTION_LIST | OPTION_REQ, 0x77},
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| 48 | #endif
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| 49 | /* MSIE's "Web Proxy Autodiscovery Protocol" support */
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| 50 | {"wpad", OPTION_STRING, 0xfc},
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| 51 | {"", 0x00, 0x00}
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[821] | 52 | };
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| 53 |
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| 54 | /* Lengths of the different option types */
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[1765] | 55 | const unsigned char option_lengths[] ALIGN1 = {
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| 56 | [OPTION_IP] = 4,
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| 57 | [OPTION_IP_PAIR] = 8,
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| 58 | [OPTION_BOOLEAN] = 1,
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| 59 | [OPTION_STRING] = 1,
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| 60 | #if ENABLE_FEATURE_RFC3397
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| 61 | [OPTION_STR1035] = 1,
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| 62 | #endif
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| 63 | [OPTION_U8] = 1,
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| 64 | [OPTION_U16] = 2,
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| 65 | [OPTION_S16] = 2,
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| 66 | [OPTION_U32] = 4,
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| 67 | [OPTION_S32] = 4
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[821] | 68 | };
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| 69 |
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| 70 |
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| 71 | /* get an option with bounds checking (warning, not aligned). */
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| 72 | uint8_t *get_option(struct dhcpMessage *packet, int code)
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| 73 | {
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| 74 | int i, length;
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| 75 | uint8_t *optionptr;
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| 76 | int over = 0, done = 0, curr = OPTION_FIELD;
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| 77 |
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| 78 | optionptr = packet->options;
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| 79 | i = 0;
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| 80 | length = 308;
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| 81 | while (!done) {
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| 82 | if (i >= length) {
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[1765] | 83 | bb_error_msg("bogus packet, option fields too long");
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[821] | 84 | return NULL;
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| 85 | }
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| 86 | if (optionptr[i + OPT_CODE] == code) {
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| 87 | if (i + 1 + optionptr[i + OPT_LEN] >= length) {
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[1765] | 88 | bb_error_msg("bogus packet, option fields too long");
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[821] | 89 | return NULL;
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| 90 | }
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| 91 | return optionptr + i + 2;
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| 92 | }
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| 93 | switch (optionptr[i + OPT_CODE]) {
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| 94 | case DHCP_PADDING:
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| 95 | i++;
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| 96 | break;
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| 97 | case DHCP_OPTION_OVER:
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| 98 | if (i + 1 + optionptr[i + OPT_LEN] >= length) {
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[1765] | 99 | bb_error_msg("bogus packet, option fields too long");
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[821] | 100 | return NULL;
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| 101 | }
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| 102 | over = optionptr[i + 3];
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| 103 | i += optionptr[OPT_LEN] + 2;
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| 104 | break;
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| 105 | case DHCP_END:
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| 106 | if (curr == OPTION_FIELD && over & FILE_FIELD) {
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| 107 | optionptr = packet->file;
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| 108 | i = 0;
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| 109 | length = 128;
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| 110 | curr = FILE_FIELD;
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| 111 | } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
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| 112 | optionptr = packet->sname;
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| 113 | i = 0;
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| 114 | length = 64;
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| 115 | curr = SNAME_FIELD;
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| 116 | } else done = 1;
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| 117 | break;
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| 118 | default:
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| 119 | i += optionptr[OPT_LEN + i] + 2;
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| 120 | }
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| 121 | }
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| 122 | return NULL;
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| 123 | }
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| 124 |
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| 125 |
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| 126 | /* return the position of the 'end' option (no bounds checking) */
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| 127 | int end_option(uint8_t *optionptr)
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| 128 | {
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| 129 | int i = 0;
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| 130 |
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| 131 | while (optionptr[i] != DHCP_END) {
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| 132 | if (optionptr[i] == DHCP_PADDING) i++;
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| 133 | else i += optionptr[i + OPT_LEN] + 2;
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| 134 | }
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| 135 | return i;
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| 136 | }
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| 137 |
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| 138 |
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| 139 | /* add an option string to the options (an option string contains an option code,
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| 140 | * length, then data) */
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| 141 | int add_option_string(uint8_t *optionptr, uint8_t *string)
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| 142 | {
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| 143 | int end = end_option(optionptr);
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| 144 |
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| 145 | /* end position + string length + option code/length + end option */
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| 146 | if (end + string[OPT_LEN] + 2 + 1 >= 308) {
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[1765] | 147 | bb_error_msg("option 0x%02x did not fit into the packet",
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| 148 | string[OPT_CODE]);
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[821] | 149 | return 0;
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| 150 | }
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[1765] | 151 | DEBUG("adding option 0x%02x", string[OPT_CODE]);
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[821] | 152 | memcpy(optionptr + end, string, string[OPT_LEN] + 2);
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| 153 | optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
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| 154 | return string[OPT_LEN] + 2;
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| 155 | }
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| 156 |
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| 157 |
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| 158 | /* add a one to four byte option to a packet */
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| 159 | int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
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| 160 | {
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[1765] | 161 | const struct dhcp_option *dh;
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[821] | 162 |
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[1765] | 163 | for (dh = dhcp_options; dh->code; dh++) {
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[821] | 164 | if (dh->code == code) {
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| 165 | uint8_t option[6], len;
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| 166 |
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| 167 | option[OPT_CODE] = code;
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| 168 | len = option_lengths[dh->flags & TYPE_MASK];
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| 169 | option[OPT_LEN] = len;
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| 170 | if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
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| 171 | /* This memcpy is for broken processors which can't
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| 172 | * handle a simple unaligned 32-bit assignment */
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| 173 | memcpy(&option[OPT_DATA], &data, 4);
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| 174 | return add_option_string(optionptr, option);
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| 175 | }
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| 176 | }
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| 177 |
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[1765] | 178 | bb_error_msg("cannot add option 0x%02x", code);
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[821] | 179 | return 0;
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| 180 | }
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