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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
Copyright © 2013 Intel Corporation. All rights reserved.
***/
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "alloc-util.h"
#include "dhcp-internal.h"
#include "dhcp-server-internal.h"
#include "memory-util.h"
#include "strv.h"
#include "utf8.h"
static int option_append(uint8_t options[], size_t size, size_t *offset,
uint8_t code, size_t optlen, const void *optval) {
assert(options);
assert(offset);
if (code != SD_DHCP_OPTION_END)
/* always make sure there is space for an END option */
size--;
switch (code) {
case SD_DHCP_OPTION_PAD:
case SD_DHCP_OPTION_END:
if (*offset + 1 > size)
return -ENOBUFS;
options[*offset] = code;
*offset += 1;
break;
case SD_DHCP_OPTION_USER_CLASS: {
size_t total = 0;
char **s;
STRV_FOREACH(s, (char **) optval) {
size_t len = strlen(*s);
if (len > 255)
return -ENAMETOOLONG;
total += 1 + len;
}
if (*offset + 2 + total > size)
return -ENOBUFS;
options[*offset] = code;
options[*offset + 1] = total;
*offset += 2;
STRV_FOREACH(s, (char **) optval) {
size_t len = strlen(*s);
options[*offset] = len;
memcpy(&options[*offset + 1], *s, len);
*offset += 1 + len;
}
break;
}
case SD_DHCP_OPTION_SIP_SERVER:
if (*offset + 3 + optlen > size)
return -ENOBUFS;
options[*offset] = code;
options[*offset + 1] = optlen + 1;
options[*offset + 2] = 1;
memcpy_safe(&options[*offset + 3], optval, optlen);
*offset += 3 + optlen;
break;
case SD_DHCP_OPTION_VENDOR_SPECIFIC: {
OrderedHashmap *s = (OrderedHashmap *) optval;
struct sd_dhcp_raw_option *p;
size_t l = 0;
Iterator i;
ORDERED_HASHMAP_FOREACH(p, s, i)
l += p->length + 2;
if (*offset + l + 2 > size)
return -ENOBUFS;
options[*offset] = code;
options[*offset + 1] = l;
*offset += 2;
ORDERED_HASHMAP_FOREACH(p, s, i) {
options[*offset] = p->type;
options[*offset + 1] = p->length;
memcpy(&options[*offset + 2], p->data, p->length);
*offset += 2 + p->length;
}
break;
}
default:
if (*offset + 2 + optlen > size)
return -ENOBUFS;
options[*offset] = code;
options[*offset + 1] = optlen;
memcpy_safe(&options[*offset + 2], optval, optlen);
*offset += 2 + optlen;
break;
}
return 0;
}
int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset,
uint8_t overload,
uint8_t code, size_t optlen, const void *optval) {
const bool use_file = overload & DHCP_OVERLOAD_FILE;
const bool use_sname = overload & DHCP_OVERLOAD_SNAME;
int r;
assert(message);
assert(offset);
/* If *offset is in range [0, size), we are writing to ->options,
* if *offset is in range [size, size + sizeof(message->file)) and use_file, we are writing to ->file,
* if *offset is in range [size + use_file*sizeof(message->file), size + use_file*sizeof(message->file) + sizeof(message->sname))
* and use_sname, we are writing to ->sname.
*/
if (*offset < size) {
/* still space in the options array */
r = option_append(message->options, size, offset, code, optlen, optval);
if (r >= 0)
return 0;
else if (r == -ENOBUFS && (use_file || use_sname)) {
/* did not fit, but we have more buffers to try
close the options array and move the offset to its end */
r = option_append(message->options, size, offset, SD_DHCP_OPTION_END, 0, NULL);
if (r < 0)
return r;
*offset = size;
} else
return r;
}
if (use_file) {
size_t file_offset = *offset - size;
if (file_offset < sizeof(message->file)) {
/* still space in the 'file' array */
r = option_append(message->file, sizeof(message->file), &file_offset, code, optlen, optval);
if (r >= 0) {
*offset = size + file_offset;
return 0;
} else if (r == -ENOBUFS && use_sname) {
/* did not fit, but we have more buffers to try
close the file array and move the offset to its end */
r = option_append(message->options, size, offset, SD_DHCP_OPTION_END, 0, NULL);
if (r < 0)
return r;
*offset = size + sizeof(message->file);
} else
return r;
}
}
if (use_sname) {
size_t sname_offset = *offset - size - use_file*sizeof(message->file);
if (sname_offset < sizeof(message->sname)) {
/* still space in the 'sname' array */
r = option_append(message->sname, sizeof(message->sname), &sname_offset, code, optlen, optval);
if (r >= 0) {
*offset = size + use_file*sizeof(message->file) + sname_offset;
return 0;
} else
/* no space, or other error, give up */
return r;
}
}
return -ENOBUFS;
}
static int parse_options(const uint8_t options[], size_t buflen, uint8_t *overload,
uint8_t *message_type, char **error_message, dhcp_option_callback_t cb,
void *userdata) {
uint8_t code, len;
const uint8_t *option;
size_t offset = 0;
while (offset < buflen) {
code = options[offset ++];
switch (code) {
case SD_DHCP_OPTION_PAD:
continue;
case SD_DHCP_OPTION_END:
return 0;
}
if (buflen < offset + 1)
return -ENOBUFS;
len = options[offset ++];
if (buflen < offset + len)
return -EINVAL;
option = &options[offset];
switch (code) {
case SD_DHCP_OPTION_MESSAGE_TYPE:
if (len != 1)
return -EINVAL;
if (message_type)
*message_type = *option;
break;
case SD_DHCP_OPTION_ERROR_MESSAGE:
if (len == 0)
return -EINVAL;
if (error_message) {
_cleanup_free_ char *string = NULL;
/* Accept a trailing NUL byte */
if (memchr(option, 0, len - 1))
return -EINVAL;
string = memdup_suffix0((const char *) option, len);
if (!string)
return -ENOMEM;
if (!ascii_is_valid(string))
return -EINVAL;
free_and_replace(*error_message, string);
}
break;
case SD_DHCP_OPTION_OVERLOAD:
if (len != 1)
return -EINVAL;
if (overload)
*overload = *option;
break;
default:
if (cb)
cb(code, len, option, userdata);
break;
}
offset += len;
}
if (offset < buflen)
return -EINVAL;
return 0;
}
int dhcp_option_parse(DHCPMessage *message, size_t len, dhcp_option_callback_t cb, void *userdata, char **_error_message) {
_cleanup_free_ char *error_message = NULL;
uint8_t overload = 0;
uint8_t message_type = 0;
int r;
if (!message)
return -EINVAL;
if (len < sizeof(DHCPMessage))
return -EINVAL;
len -= sizeof(DHCPMessage);
r = parse_options(message->options, len, &overload, &message_type, &error_message, cb, userdata);
if (r < 0)
return r;
if (overload & DHCP_OVERLOAD_FILE) {
r = parse_options(message->file, sizeof(message->file), NULL, &message_type, &error_message, cb, userdata);
if (r < 0)
return r;
}
if (overload & DHCP_OVERLOAD_SNAME) {
r = parse_options(message->sname, sizeof(message->sname), NULL, &message_type, &error_message, cb, userdata);
if (r < 0)
return r;
}
if (message_type == 0)
return -ENOMSG;
if (_error_message && IN_SET(message_type, DHCP_NAK, DHCP_DECLINE))
*_error_message = TAKE_PTR(error_message);
return message_type;
}
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