20b958bf15
Store a pointer to the options in the DHCPMessage struct, and pass this together with an offset around, rather than a uint8_t**. This avoids us having to (re)compute the pointer; and changes dhcp_option_append from adjusting both the pointer to the next option and the remaining size of the options, to just adjusting the current offset. This makes the code a bit simpler to follow IMHO, but there should be no functional change.
176 lines
4.8 KiB
C
176 lines
4.8 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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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 <stdint.h>
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#include <string.h>
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#include <errno.h>
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#include <stdio.h>
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#include "dhcp-internal.h"
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int dhcp_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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switch (code) {
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case DHCP_OPTION_PAD:
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case 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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assert(optval);
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options[*offset] = code;
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options[*offset + 1] = optlen;
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memcpy(&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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static int parse_options(const uint8_t *buf, size_t buflen, uint8_t *overload,
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uint8_t *message_type, dhcp_option_cb_t cb,
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void *user_data)
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{
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const uint8_t *code = buf;
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const uint8_t *len;
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while (buflen > 0) {
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switch (*code) {
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case DHCP_OPTION_PAD:
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buflen -= 1;
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code++;
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break;
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case DHCP_OPTION_END:
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return 0;
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case DHCP_OPTION_MESSAGE_TYPE:
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if (buflen < 3)
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return -ENOBUFS;
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buflen -= 3;
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len = code + 1;
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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 = *(len + 1);
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code += 3;
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break;
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case DHCP_OPTION_OVERLOAD:
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if (buflen < 3)
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return -ENOBUFS;
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buflen -= 3;
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len = code + 1;
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if (*len != 1)
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return -EINVAL;
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if (overload)
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*overload = *(len + 1);
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code += 3;
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break;
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default:
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if (buflen < 3)
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return -ENOBUFS;
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len = code + 1;
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if (buflen < (size_t)*len + 2)
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return -EINVAL;
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buflen -= *len + 2;
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if (cb)
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cb(*code, *len, len + 1, user_data);
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code += *len + 2;
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break;
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}
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}
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if (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,
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dhcp_option_cb_t cb, void *user_data)
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{
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uint8_t overload = 0;
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uint8_t message_type = 0;
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int res;
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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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res = parse_options(message->options, len, &overload, &message_type,
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cb, user_data);
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if (res < 0)
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return res;
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if (overload & DHCP_OVERLOAD_FILE) {
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res = parse_options(message->file, sizeof(message->file),
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NULL, &message_type, cb, user_data);
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if (res < 0)
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return res;
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}
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if (overload & DHCP_OVERLOAD_SNAME) {
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res = parse_options(message->sname, sizeof(message->sname),
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NULL, &message_type, cb, user_data);
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if (res < 0)
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return res;
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}
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if (message_type)
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return message_type;
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return -ENOMSG;
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}
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