LeOS-Genesis/external/badvpn/misc/udp_proto.h

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2020-10-05 13:12:00 +02:00
/**
* @file udp_proto.h
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @section DESCRIPTION
*
* Definitions for the UDP protocol.
*/
#ifndef BADVPN_MISC_UDP_PROTO_H
#define BADVPN_MISC_UDP_PROTO_H
#include <stdint.h>
#include <misc/debug.h>
#include <misc/byteorder.h>
#include <misc/ipv4_proto.h>
#include <misc/ipv6_proto.h>
#include <misc/read_write_int.h>
B_START_PACKED
struct udp_header {
uint16_t source_port;
uint16_t dest_port;
uint16_t length;
uint16_t checksum;
} B_PACKED;
B_END_PACKED
static uint32_t udp_checksum_summer (const char *data, uint16_t len)
{
ASSERT(len % 2 == 0)
uint32_t t = 0;
for (uint16_t i = 0; i < len / 2; i++) {
t += badvpn_read_be16(data + 2 * i);
}
return t;
}
static uint16_t udp_checksum (const struct udp_header *header, const uint8_t *payload, uint16_t payload_len, uint32_t source_addr, uint32_t dest_addr)
{
uint32_t t = 0;
t += udp_checksum_summer((char *)&source_addr, sizeof(source_addr));
t += udp_checksum_summer((char *)&dest_addr, sizeof(dest_addr));
uint16_t x;
x = hton16(IPV4_PROTOCOL_UDP);
t += udp_checksum_summer((char *)&x, sizeof(x));
x = hton16(sizeof(*header) + payload_len);
t += udp_checksum_summer((char *)&x, sizeof(x));
t += udp_checksum_summer((const char *)header, sizeof(*header));
if (payload_len % 2 == 0) {
t += udp_checksum_summer((const char *)payload, payload_len);
} else {
t += udp_checksum_summer((const char *)payload, payload_len - 1);
x = hton16(((uint16_t)payload[payload_len - 1]) << 8);
t += udp_checksum_summer((char *)&x, sizeof(x));
}
while (t >> 16) {
t = (t & 0xFFFF) + (t >> 16);
}
if (t == 0) {
t = UINT16_MAX;
}
return hton16(~t);
}
static uint16_t udp_ip6_checksum (const struct udp_header *header, const uint8_t *payload, uint16_t payload_len, const uint8_t *source_addr, const uint8_t *dest_addr)
{
uint32_t t = 0;
t += udp_checksum_summer((const char *)source_addr, 16);
t += udp_checksum_summer((const char *)dest_addr, 16);
uint32_t x;
x = hton32(sizeof(*header) + payload_len);
t += udp_checksum_summer((char *)&x, sizeof(x));
x = hton32(IPV6_NEXT_UDP);
t += udp_checksum_summer((char *)&x, sizeof(x));
t += udp_checksum_summer((const char *)header, sizeof(*header));
if (payload_len % 2 == 0) {
t += udp_checksum_summer((const char *)payload, payload_len);
} else {
t += udp_checksum_summer((const char *)payload, payload_len - 1);
uint16_t y;
y = hton16(((uint16_t)payload[payload_len - 1]) << 8);
t += udp_checksum_summer((char *)&y, sizeof(y));
}
while (t >> 16) {
t = (t & 0xFFFF) + (t >> 16);
}
if (t == 0) {
t = UINT16_MAX;
}
return hton16(~t);
}
static int udp_check (const uint8_t *data, int data_len, struct udp_header *out_header, uint8_t **out_payload, int *out_payload_len)
{
ASSERT(data_len >= 0)
ASSERT(out_header)
ASSERT(out_payload)
ASSERT(out_payload_len)
// parse UDP header
if (data_len < sizeof(struct udp_header)) {
return 0;
}
memcpy(out_header, data, sizeof(*out_header));
data += sizeof(*out_header);
data_len -= sizeof(*out_header);
// verify UDP payload
int udp_length = ntoh16(out_header->length);
if (udp_length < sizeof(*out_header)) {
return 0;
}
if (udp_length > sizeof(*out_header) + data_len) {
return 0;
}
// ignore stray data
data_len = udp_length - sizeof(*out_header);
*out_payload = (uint8_t *)data;
*out_payload_len = data_len;
return 1;
}
#endif