87 lines
1.5 KiB
Go
87 lines
1.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package net
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import "syscall"
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func kernelVersion() (major int, minor int) {
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var uname syscall.Utsname
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if err := syscall.Uname(&uname); err != nil {
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return
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}
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rl := uname.Release
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var values [2]int
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vi := 0
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value := 0
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for _, c := range rl {
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if c >= '0' && c <= '9' {
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value = (value * 10) + int(c-'0')
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} else {
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// Note that we're assuming N.N.N here. If we see anything else we are likely to
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// mis-parse it.
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values[vi] = value
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vi++
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if vi >= len(values) {
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break
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}
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value = 0
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}
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}
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switch vi {
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case 0:
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return 0, 0
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case 1:
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return values[0], 0
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case 2:
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return values[0], values[1]
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}
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return
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}
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// Linux stores the backlog as:
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//
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// - uint16 in kernel version < 4.1,
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// - uint32 in kernel version >= 4.1
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//
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// Truncate number to avoid wrapping.
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//
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// See issue 5030 and 41470.
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func maxAckBacklog(n int) int {
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major, minor := kernelVersion()
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size := 16
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if major > 4 || (major == 4 && minor >= 1) {
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size = 32
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}
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var max uint = 1<<size - 1
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if uint(n) > max {
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n = int(max)
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}
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return n
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}
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func maxListenerBacklog() int {
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fd, err := open("/proc/sys/net/core/somaxconn")
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if err != nil {
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return syscall.SOMAXCONN
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}
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defer fd.close()
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l, ok := fd.readLine()
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if !ok {
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return syscall.SOMAXCONN
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}
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f := getFields(l)
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n, _, ok := dtoi(f[0])
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if n == 0 || !ok {
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return syscall.SOMAXCONN
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}
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if n > 1<<16-1 {
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return maxAckBacklog(n)
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}
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return n
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}
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