cf6dbe48e0
This commit changes our system resolver to call getaddrinfo directly when CGO is enabled. This change allows us to: 1. obtain the CNAME easily 2. obtain the real getaddrinfo retval 3. handle platform specific oddities such as `EAI_NODATA` returned on Android devices See https://github.com/ooni/probe/issues/2029 and https://github.com/ooni/probe/issues/2029#issuecomment-1140258729 in particular. See https://github.com/ooni/probe/issues/2033 for documentation regarding the desire to see `getaddrinfo`'s retval. See https://github.com/ooni/probe/issues/2118 for possible follow-up changes.
59 lines
1.8 KiB
Go
59 lines
1.8 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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//go:build cgo && (darwin || dragonfly || freebsd || openbsd)
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package netxlite
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/*
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#include <netdb.h>
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*/
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import "C"
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import (
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"syscall"
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)
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const getaddrinfoAIFlags = (C.AI_CANONNAME | C.AI_V4MAPPED | C.AI_ALL) & C.AI_MASK
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// Making constants available to Go code so we can run tests
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const (
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aiCanonname = C.AI_CANONNAME
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aiV4Mapped = C.AI_V4MAPPED
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aiAll = C.AI_ALL
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aiMask = C.AI_MASK
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eaiSystem = C.EAI_SYSTEM
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eaiNoName = C.EAI_NONAME
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eaiBadFlags = C.EAI_BADFLAGS
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)
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// toError is the function that converts the return value from
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// the getaddrinfo function into a proper Go error.
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//
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// This function is adapted from cgoLookupIPCNAME
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// https://github.com/golang/go/blob/go1.17.6/src/net/cgo_unix.go#L145
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//
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// SPDX-License-Identifier: BSD-3-Clause.
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func (state *getaddrinfoState) toError(code int64, err error, goos string) error {
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switch code {
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case C.EAI_SYSTEM:
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if err == nil {
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// err should not be nil, but sometimes getaddrinfo returns
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// code == C.EAI_SYSTEM with err == nil on Linux.
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// The report claims that it happens when we have too many
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// open files, so use syscall.EMFILE (too many open files in system).
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// Most system calls would return ENFILE (too many open files),
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// so at the least EMFILE should be easy to recognize if this
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// comes up again. golang.org/issue/6232.
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err = syscall.EMFILE
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}
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return newErrGetaddrinfo(code, err)
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case C.EAI_NONAME:
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err = ErrOODNSNoSuchHost // so it becomes FailureDNSNXDOMAIN
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return newErrGetaddrinfo(code, err)
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default:
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err = ErrOODNSMisbehaving // so it becomes FailureDNSServerMisbehaving
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return newErrGetaddrinfo(code, err)
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}
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}
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