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Diffstat (limited to 'ring.h')
-rw-r--r-- | ring.h | 55 |
1 files changed, 55 insertions, 0 deletions
@@ -0,0 +1,55 @@ +/* + * 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(MAXMTU) + 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 65536 + +// 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 + +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 |