45 lines
1.6 KiB
Go
45 lines
1.6 KiB
Go
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// Licensed to Elasticsearch B.V. under one or more contributor
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// license agreements. See the NOTICE file distributed with
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// this work for additional information regarding copyright
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// ownership. Elasticsearch B.V. licenses this file to you under
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// the Apache License, Version 2.0 (the "License"); you may
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// 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,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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package sniffer
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import "fmt"
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// Computes the block_size and the num_blocks in such a way that the
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// allocated mmap buffer is close to but smaller than target_size_mb.
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// The restriction is that the block_size must be divisible by both the
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// frame size and page size.
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func afpacketComputeSize(targetSizeMb int, snaplen int, pageSize int) (
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frameSize int, blockSize int, numBlocks int, err error) {
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if snaplen < pageSize {
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frameSize = pageSize / (pageSize / snaplen)
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} else {
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frameSize = (snaplen/pageSize + 1) * pageSize
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}
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// 128 is the default from the gopacket library so just use that
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blockSize = frameSize * 128
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numBlocks = (targetSizeMb * 1024 * 1024) / blockSize
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if numBlocks == 0 {
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return 0, 0, 0, fmt.Errorf("Buffer size too small")
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}
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return frameSize, blockSize, numBlocks, nil
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}
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