64 lines
1.9 KiB
Go
64 lines
1.9 KiB
Go
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// Copyright 2020 The gVisor Authors.
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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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package iptables
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import (
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"fmt"
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"syscall"
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"unsafe"
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)
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type originalDstError struct {
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errno syscall.Errno
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}
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func (e originalDstError) Error() string {
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return fmt.Sprintf("errno (%d) when calling getsockopt(SO_ORIGINAL_DST): %v", int(e.errno), e.errno.Error())
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}
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// SO_ORIGINAL_DST gets the original destination of a redirected packet via
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// getsockopt.
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const SO_ORIGINAL_DST = 80
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func originalDestination4(connfd int) (syscall.RawSockaddrInet4, error) {
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var addr syscall.RawSockaddrInet4
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var addrLen uint32 = syscall.SizeofSockaddrInet4
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if errno := originalDestination(connfd, syscall.SOL_IP, unsafe.Pointer(&addr), &addrLen); errno != 0 {
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return syscall.RawSockaddrInet4{}, originalDstError{errno}
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}
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return addr, nil
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}
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func originalDestination6(connfd int) (syscall.RawSockaddrInet6, error) {
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var addr syscall.RawSockaddrInet6
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var addrLen uint32 = syscall.SizeofSockaddrInet6
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if errno := originalDestination(connfd, syscall.SOL_IPV6, unsafe.Pointer(&addr), &addrLen); errno != 0 {
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return syscall.RawSockaddrInet6{}, originalDstError{errno}
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}
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return addr, nil
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}
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func originalDestination(connfd int, level uintptr, optval unsafe.Pointer, optlen *uint32) syscall.Errno {
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_, _, errno := syscall.Syscall6(
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syscall.SYS_GETSOCKOPT,
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uintptr(connfd),
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level,
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SO_ORIGINAL_DST,
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uintptr(optval),
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uintptr(unsafe.Pointer(optlen)),
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0)
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return errno
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}
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