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/*
* Copyright 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* ring.c - packet ring buffer functions
*/
#ifndef __RING_H__
#define __RING_H__
#include <linux/if.h>
#include <linux/if_packet.h>
#include "clatd.h"
struct tun_data;
// Frame size. Must be a multiple of TPACKET_ALIGNMENT (=16)
// Why the 16? http://lxr.free-electrons.com/source/net/packet/af_packet.c?v=3.4#L1764
#define TP_FRAME_SIZE (TPACKET_ALIGN(MAXMRU) + TPACKET_ALIGN(TPACKET2_HDRLEN) + 16)
// Block size. Must be a multiple of the page size, and a power of two for efficient memory use.
#define TP_BLOCK_SIZE 2686976
// In order to save memory, our frames are not an exact divider of the block size. Therefore, the
// mmaped region will have gaps corresponding to the empty space at the end of each block.
#define TP_FRAMES (TP_BLOCK_SIZE / TP_FRAME_SIZE)
#define TP_FRAME_GAP (TP_BLOCK_SIZE % TP_FRAME_SIZE)
// TODO: Make this configurable. This requires some refactoring because the packet socket is
// opened before we drop privileges, but the configuration file is read after. A value of 16
// results in 656 frames (1048576 bytes).
#define TP_NUM_BLOCKS 16
#define TP_CSUM_NONE (0)
#define TP_CSUM_UNNECESSARY (1)
struct packet_ring {
uint8_t *base;
struct tpacket2_hdr *next;
int slot, numslots;
int block, numblocks;
};
int ring_create(struct tun_data *tunnel);
void ring_read(struct packet_ring *ring, int write_fd, int to_ipv6);
#endif
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