forked from github/multus-cni
ac21a96804
gomodule is still in progress to migrate for now, hence multus team decide to keep vendor directory to support build without gomodule.
118 lines
3.1 KiB
Go
118 lines
3.1 KiB
Go
// Copyright 2011 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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// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris
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// Socket control messages
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package unix
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import (
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"runtime"
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"unsafe"
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)
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// Round the length of a raw sockaddr up to align it properly.
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func cmsgAlignOf(salen int) int {
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salign := SizeofPtr
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switch runtime.GOOS {
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case "darwin", "dragonfly", "solaris":
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// NOTE: It seems like 64-bit Darwin, DragonFly BSD and
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// Solaris kernels still require 32-bit aligned access to
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// network subsystem.
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if SizeofPtr == 8 {
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salign = 4
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}
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case "openbsd":
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// OpenBSD armv7 requires 64-bit alignment.
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if runtime.GOARCH == "arm" {
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salign = 8
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}
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}
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return (salen + salign - 1) & ^(salign - 1)
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}
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// CmsgLen returns the value to store in the Len field of the Cmsghdr
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// structure, taking into account any necessary alignment.
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func CmsgLen(datalen int) int {
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return cmsgAlignOf(SizeofCmsghdr) + datalen
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}
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// CmsgSpace returns the number of bytes an ancillary element with
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// payload of the passed data length occupies.
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func CmsgSpace(datalen int) int {
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return cmsgAlignOf(SizeofCmsghdr) + cmsgAlignOf(datalen)
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}
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func cmsgData(h *Cmsghdr) unsafe.Pointer {
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return unsafe.Pointer(uintptr(unsafe.Pointer(h)) + uintptr(cmsgAlignOf(SizeofCmsghdr)))
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}
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// SocketControlMessage represents a socket control message.
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type SocketControlMessage struct {
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Header Cmsghdr
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Data []byte
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}
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// ParseSocketControlMessage parses b as an array of socket control
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// messages.
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func ParseSocketControlMessage(b []byte) ([]SocketControlMessage, error) {
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var msgs []SocketControlMessage
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i := 0
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for i+CmsgLen(0) <= len(b) {
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h, dbuf, err := socketControlMessageHeaderAndData(b[i:])
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if err != nil {
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return nil, err
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}
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m := SocketControlMessage{Header: *h, Data: dbuf}
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msgs = append(msgs, m)
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i += cmsgAlignOf(int(h.Len))
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}
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return msgs, nil
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}
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func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) {
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h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
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if h.Len < SizeofCmsghdr || uint64(h.Len) > uint64(len(b)) {
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return nil, nil, EINVAL
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}
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return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil
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}
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// UnixRights encodes a set of open file descriptors into a socket
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// control message for sending to another process.
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func UnixRights(fds ...int) []byte {
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datalen := len(fds) * 4
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b := make([]byte, CmsgSpace(datalen))
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h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
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h.Level = SOL_SOCKET
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h.Type = SCM_RIGHTS
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h.SetLen(CmsgLen(datalen))
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data := cmsgData(h)
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for _, fd := range fds {
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*(*int32)(data) = int32(fd)
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data = unsafe.Pointer(uintptr(data) + 4)
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}
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return b
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}
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// ParseUnixRights decodes a socket control message that contains an
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// integer array of open file descriptors from another process.
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func ParseUnixRights(m *SocketControlMessage) ([]int, error) {
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if m.Header.Level != SOL_SOCKET {
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return nil, EINVAL
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}
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if m.Header.Type != SCM_RIGHTS {
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return nil, EINVAL
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}
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fds := make([]int, len(m.Data)>>2)
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for i, j := 0, 0; i < len(m.Data); i += 4 {
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fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i])))
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j++
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}
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return fds, nil
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}
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