261 lines
8.6 KiB
C
261 lines
8.6 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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/***
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This file is part of systemd.
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Copyright (C) 2013 Intel Corporation. All rights reserved.
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include "alloc-util.h"
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#include "utf8.h"
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#include "dhcp-internal.h"
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static int option_append(uint8_t options[], size_t size, size_t *offset,
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uint8_t code, size_t optlen, const void *optval) {
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assert(options);
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assert(offset);
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if (code != SD_DHCP_OPTION_END)
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/* always make sure there is space for an END option */
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size--;
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switch (code) {
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case SD_DHCP_OPTION_PAD:
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case SD_DHCP_OPTION_END:
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if (size < *offset + 1)
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return -ENOBUFS;
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options[*offset] = code;
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*offset += 1;
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break;
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default:
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if (size < *offset + optlen + 2)
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return -ENOBUFS;
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options[*offset] = code;
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options[*offset + 1] = optlen;
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memcpy_safe(&options[*offset + 2], optval, optlen);
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*offset += optlen + 2;
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break;
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}
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return 0;
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}
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int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset,
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uint8_t overload,
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uint8_t code, size_t optlen, const void *optval) {
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size_t file_offset = 0, sname_offset =0;
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bool file, sname;
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int r;
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assert(message);
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assert(offset);
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file = overload & DHCP_OVERLOAD_FILE;
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sname = overload & DHCP_OVERLOAD_SNAME;
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if (*offset < size) {
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/* still space in the options array */
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r = option_append(message->options, size, offset, code, optlen, optval);
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if (r >= 0)
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return 0;
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else if (r == -ENOBUFS && (file || sname)) {
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/* did not fit, but we have more buffers to try
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close the options array and move the offset to its end */
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r = option_append(message->options, size, offset, SD_DHCP_OPTION_END, 0, NULL);
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if (r < 0)
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return r;
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*offset = size;
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} else
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return r;
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}
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if (overload & DHCP_OVERLOAD_FILE) {
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file_offset = *offset - size;
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if (file_offset < sizeof(message->file)) {
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/* still space in the 'file' array */
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r = option_append(message->file, sizeof(message->file), &file_offset, code, optlen, optval);
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if (r >= 0) {
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*offset = size + file_offset;
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return 0;
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} else if (r == -ENOBUFS && sname) {
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/* did not fit, but we have more buffers to try
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close the file array and move the offset to its end */
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r = option_append(message->options, size, offset, SD_DHCP_OPTION_END, 0, NULL);
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if (r < 0)
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return r;
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*offset = size + sizeof(message->file);
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} else
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return r;
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}
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}
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if (overload & DHCP_OVERLOAD_SNAME) {
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sname_offset = *offset - size - (file ? sizeof(message->file) : 0);
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if (sname_offset < sizeof(message->sname)) {
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/* still space in the 'sname' array */
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r = option_append(message->sname, sizeof(message->sname), &sname_offset, code, optlen, optval);
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if (r >= 0) {
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*offset = size + (file ? sizeof(message->file) : 0) + sname_offset;
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return 0;
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} else {
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/* no space, or other error, give up */
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return r;
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}
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}
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}
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return -ENOBUFS;
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}
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static int parse_options(const uint8_t options[], size_t buflen, uint8_t *overload,
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uint8_t *message_type, char **error_message, dhcp_option_callback_t cb,
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void *userdata) {
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uint8_t code, len;
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const uint8_t *option;
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size_t offset = 0;
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while (offset < buflen) {
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code = options[offset ++];
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switch (code) {
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case SD_DHCP_OPTION_PAD:
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continue;
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case SD_DHCP_OPTION_END:
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return 0;
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}
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if (buflen < offset + 1)
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return -ENOBUFS;
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len = options[offset ++];
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if (buflen < offset + len)
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return -EINVAL;
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option = &options[offset];
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switch (code) {
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case SD_DHCP_OPTION_MESSAGE_TYPE:
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if (len != 1)
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return -EINVAL;
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if (message_type)
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*message_type = *option;
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break;
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case SD_DHCP_OPTION_ERROR_MESSAGE:
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if (len == 0)
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return -EINVAL;
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if (error_message) {
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_cleanup_free_ char *string = NULL;
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/* Accept a trailing NUL byte */
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if (memchr(option, 0, len - 1))
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return -EINVAL;
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string = strndup((const char *) option, len);
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if (!string)
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return -ENOMEM;
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if (!ascii_is_valid(string))
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return -EINVAL;
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free_and_replace(*error_message, string);
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}
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break;
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case SD_DHCP_OPTION_OVERLOAD:
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if (len != 1)
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return -EINVAL;
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if (overload)
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*overload = *option;
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break;
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default:
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if (cb)
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cb(code, len, option, userdata);
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break;
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}
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offset += len;
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}
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if (offset < buflen)
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return -EINVAL;
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return 0;
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}
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int dhcp_option_parse(DHCPMessage *message, size_t len, dhcp_option_callback_t cb, void *userdata, char **_error_message) {
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_cleanup_free_ char *error_message = NULL;
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uint8_t overload = 0;
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uint8_t message_type = 0;
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int r;
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if (!message)
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return -EINVAL;
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if (len < sizeof(DHCPMessage))
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return -EINVAL;
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len -= sizeof(DHCPMessage);
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r = parse_options(message->options, len, &overload, &message_type, &error_message, cb, userdata);
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if (r < 0)
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return r;
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if (overload & DHCP_OVERLOAD_FILE) {
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r = parse_options(message->file, sizeof(message->file), NULL, &message_type, &error_message, cb, userdata);
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if (r < 0)
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return r;
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}
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if (overload & DHCP_OVERLOAD_SNAME) {
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r = parse_options(message->sname, sizeof(message->sname), NULL, &message_type, &error_message, cb, userdata);
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if (r < 0)
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return r;
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}
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if (message_type == 0)
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return -ENOMSG;
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if (_error_message && IN_SET(message_type, DHCP_NAK, DHCP_DECLINE))
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*_error_message = TAKE_PTR(error_message);
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return message_type;
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}
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