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56 lines
1.9 KiB
56 lines
1.9 KiB
/*
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* Copyright 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* ring.c - packet ring buffer functions
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*/
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#ifndef __RING_H__
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#define __RING_H__
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#include <linux/if.h>
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#include <linux/if_packet.h>
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#include "clatd.h"
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struct tun_data;
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// Frame size. Must be a multiple of TPACKET_ALIGNMENT (=16)
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// Why the 16? http://lxr.free-electrons.com/source/net/packet/af_packet.c?v=3.4#L1764
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#define TP_FRAME_SIZE (TPACKET_ALIGN(MAXMTU) + TPACKET_ALIGN(TPACKET2_HDRLEN) + 16)
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// Block size. Must be a multiple of the page size, and a power of two for efficient memory use.
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#define TP_BLOCK_SIZE 65536
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// In order to save memory, our frames are not an exact divider of the block size. Therefore, the
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// mmaped region will have gaps corresponding to the empty space at the end of each block.
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#define TP_FRAMES (TP_BLOCK_SIZE / TP_FRAME_SIZE)
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#define TP_FRAME_GAP (TP_BLOCK_SIZE % TP_FRAME_SIZE)
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// TODO: Make this configurable. This requires some refactoring because the packet socket is
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// opened before we drop privileges, but the configuration file is read after. A value of 16
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// results in 656 frames (1048576 bytes).
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#define TP_NUM_BLOCKS 16
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struct packet_ring {
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uint8_t *base;
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struct tpacket2_hdr *next;
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int slot, numslots;
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int block, numblocks;
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};
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int ring_create(struct tun_data *tunnel);
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void ring_read(struct packet_ring *ring, int write_fd, int to_ipv6);
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#endif
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