mirror of
https://github.com/golang/go
synced 2024-09-29 13:24:28 -06:00
net: remove non-cgo macOS resolver code
The built-in Go resolver works significantly better. In particular, the use of res_search does not support CNAME or PTR queries and may not even be thread-safe. This CL is essentially a revert of CL 166297 plus fixes, including CL 180842. See CL 180842 for additional notes about problems with this approach. Fixes #31705. Change-Id: I0a30a0de2fbd04f6c461520fd34378c84aadf66c Reviewed-on: https://go-review.googlesource.com/c/go/+/180843 Run-TryBot: Russ Cox <rsc@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Russ Cox
parent
705830e2b7
commit
d32ec38f1c
@ -1,242 +0,0 @@
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// Copyright 2019 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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// This file is intended to be used in non-cgo builds of darwin binaries,
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// in particular when cross-compiling a darwin binary from a non-darwin machine.
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// All OS calls on darwin have to be done via C libraries, and this code makes such
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// calls with the runtime's help. (It is a C call but does not require the cgo tool to
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// be compiled, and as such it is possible to build even when cross-compiling.)
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//
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// The specific C library calls are to res_init and res_search from /usr/lib/system/libsystem_info.dylib.
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// Unfortunately, an ordinary C program calling these names would actually end up with
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// res_9_init and res_9_search from /usr/lib/libresolv.dylib, not libsystem_info.
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// It may well be that the libsystem_info routines are completely unused on macOS systems
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// except for this code. At the least, they have the following problems:
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//
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// - TypeALL requests do not work, so if we want both IPv4 and IPv6 addresses,
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// we have to do two requests, one for TypeA and one for TypeAAAA.
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// - TypeCNAME requests hang indefinitely.
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// - TypePTR requests fail unconditionally.
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// - Detailed error information is stored in the global h_errno value,
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// which cannot be accessed safely (it is not per-thread like errno).
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// - The routines may not be safe to call from multiple threads.
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// If you run net.test under lldb, that emits syslog prints to stderr
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// that suggest double-free problems. (If not running under lldb,
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// it is unclear where the syslog prints go, if anywhere.)
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//
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// This code is marked for deletion. If it is to be revived, it should be changed to use
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// res_9_init and res_9_search from libresolv and special care should be paid to
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// error detail and thread safety.
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// +build !netgo,!cgo
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// +build darwin
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package net
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import (
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"context"
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"errors"
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"sync"
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"golang.org/x/net/dns/dnsmessage"
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)
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type addrinfoErrno int
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func (eai addrinfoErrno) Error() string { return "<nil>" }
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func (eai addrinfoErrno) Temporary() bool { return false }
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func (eai addrinfoErrno) Timeout() bool { return false }
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func cgoLookupHost(ctx context.Context, name string) (addrs []string, err error, completed bool) {
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// The 4-suffix indicates IPv4, TypeA lookups.
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// The 6-suffix indicates IPv6, TypeAAAA lookups.
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// If resSearch is updated to call the libresolv res_9_search (see comment at top of file),
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// it may be possible to make one call for TypeALL
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// and get both address kinds out.
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r4, err4 := resSearch(ctx, name, int32(dnsmessage.TypeA), int32(dnsmessage.ClassINET))
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if err4 == nil {
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addrs, err4 = appendHostsFromResources(addrs, r4)
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}
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r6, err6 := resSearch(ctx, name, int32(dnsmessage.TypeAAAA), int32(dnsmessage.ClassINET))
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if err6 == nil {
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addrs, err6 = appendHostsFromResources(addrs, r6)
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}
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if err4 != nil && err6 != nil {
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return nil, err4, false
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}
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return addrs, nil, true
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}
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func cgoLookupPort(ctx context.Context, network, service string) (port int, err error, completed bool) {
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port, err = goLookupPort(network, service) // we can just use netgo lookup
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return port, err, err == nil
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}
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func cgoLookupIP(ctx context.Context, network, name string) (addrs []IPAddr, err error, completed bool) {
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// The 4-suffix indicates IPv4, TypeA lookups.
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// The 6-suffix indicates IPv6, TypeAAAA lookups.
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// If resSearch is updated to call the libresolv res_9_search (see comment at top of file),
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// it may be possible to make one call for TypeALL (when vers != '6' and vers != '4')
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// and get both address kinds out.
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var r4, r6 []dnsmessage.Resource
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var err4, err6 error
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vers := ipVersion(network)
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if vers != '6' {
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r4, err4 = resSearch(ctx, name, int32(dnsmessage.TypeA), int32(dnsmessage.ClassINET))
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if err4 == nil {
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addrs, err4 = appendIPsFromResources(addrs, r4)
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}
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}
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if vers != '4' {
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r6, err6 = resSearch(ctx, name, int32(dnsmessage.TypeAAAA), int32(dnsmessage.ClassINET))
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if err6 == nil {
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addrs, err6 = appendIPsFromResources(addrs, r6)
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}
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}
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if err4 != nil && err6 != nil {
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return nil, err4, false
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}
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return addrs, nil, true
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}
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func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error, completed bool) {
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resources, err := resSearch(ctx, name, int32(dnsmessage.TypeCNAME), int32(dnsmessage.ClassINET))
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if err != nil {
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return
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}
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cname, err = parseCNAMEFromResources(resources)
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if err != nil {
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return "", err, false
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}
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return cname, nil, true
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}
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func cgoLookupPTR(ctx context.Context, addr string) (ptrs []string, err error, completed bool) {
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resources, err := resSearch(ctx, addr, int32(dnsmessage.TypePTR), int32(dnsmessage.ClassINET))
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if err != nil {
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return
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}
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ptrs, err = parsePTRsFromResources(resources)
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if err != nil {
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return
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}
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return ptrs, nil, true
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}
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var (
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resInitOnce sync.Once
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resInitResult int32
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)
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// resSearch will make a call to the 'res_search' routine in libSystem
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// and parse the output as a slice of resource resources which can then be parsed
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func resSearch(ctx context.Context, hostname string, rtype, class int32) ([]dnsmessage.Resource, error) {
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// We have to use res_init and res_search, but these do not set errno on failure.
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// (They set h_errno, which is a global int shared by all threads and therefore
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// racy to use.)
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// https://opensource.apple.com/source/Libinfo/Libinfo-517.200.9/dns.subproj/res_query.c.auto.html
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resInitOnce.Do(func() {
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resInitResult = res_init()
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})
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if resInitResult < 0 {
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return nil, errors.New("res_init failure")
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}
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// res_search does not set errno.
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// It returns the size of the DNS response packet.
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// But if the DNS response packet contains failure-like response codes,
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// res_search returns -1 even though it has copied the packet into buf,
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// giving us no way to find out how big the packet is.
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// For now, we are willing to take res_search's word that there's nothing
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// useful in the response, even though there *is* a response.
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name := make([]byte, len(hostname)+1) // +1 for NUL at end for C
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copy(name, hostname)
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var buf [1024]byte
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size, _ := res_search(&name[0], class, rtype, &buf[0], int32(len(buf)))
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if size <= 0 {
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return nil, errors.New("res_search failure")
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}
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var p dnsmessage.Parser
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if _, err := p.Start(buf[:size]); err != nil {
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return nil, err
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}
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p.SkipAllQuestions()
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resources, err := p.AllAnswers()
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if err != nil {
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return nil, err
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}
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return resources, nil
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}
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func copyBytes(x []byte) []byte {
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y := make([]byte, len(x))
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copy(y, x)
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return y
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}
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func appendHostsFromResources(answers []string, resources []dnsmessage.Resource) ([]string, error) {
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for i := range resources {
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switch resources[i].Header.Type {
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case dnsmessage.TypeA:
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b := resources[i].Body.(*dnsmessage.AResource)
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answers = append(answers, IP(b.A[:]).String())
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case dnsmessage.TypeAAAA:
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b := resources[i].Body.(*dnsmessage.AAAAResource)
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answers = append(answers, IP(b.AAAA[:]).String())
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default:
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return nil, errors.New("could not parse an A or AAAA response from message buffer")
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}
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}
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return answers, nil
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}
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func appendIPsFromResources(answers []IPAddr, resources []dnsmessage.Resource) ([]IPAddr, error) {
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for i := range resources {
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switch resources[i].Header.Type {
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case dnsmessage.TypeA:
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b := resources[i].Body.(*dnsmessage.AResource)
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answers = append(answers, IPAddr{IP: IP(copyBytes(b.A[:]))})
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case dnsmessage.TypeAAAA:
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b := resources[i].Body.(*dnsmessage.AAAAResource)
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answers = append(answers, IPAddr{IP: IP(copyBytes(b.AAAA[:]))})
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default:
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return nil, errors.New("could not parse an A or AAAA response from message buffer")
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}
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}
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return answers, nil
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}
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func parseCNAMEFromResources(resources []dnsmessage.Resource) (string, error) {
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if len(resources) == 0 {
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return "", errors.New("no CNAME record received")
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}
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c, ok := resources[0].Body.(*dnsmessage.CNAMEResource)
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if !ok {
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return "", errors.New("could not parse CNAME record")
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}
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return c.CNAME.String(), nil
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}
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func parsePTRsFromResources(resources []dnsmessage.Resource) ([]string, error) {
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var answers []string
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for i := range resources {
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switch resources[i].Header.Type {
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case dnsmessage.TypePTR:
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p := resources[0].Body.(*dnsmessage.PTRResource)
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answers = append(answers, p.PTR.String())
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default:
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return nil, errors.New("could not parse a PTR response from message buffer")
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}
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}
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return answers, nil
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}
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// res_init and res_search are defined in runtime/lookup_darwin.go
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func res_init() int32
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func res_search(dname *byte, class int32, rtype int32, answer *byte, anslen int32) (int32, int32)
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@ -1,80 +0,0 @@
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// Copyright 2019 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 !netgo,!cgo
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// +build darwin
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package net
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import (
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"context"
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"strings"
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"testing"
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)
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func TestPseudoCgoLookupHost(t *testing.T) {
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addrs, err, ok := cgoLookupHost(context.Background(), "google.com")
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t.Logf("cgoLookupHost google.com: %v %v %v", addrs, err, ok)
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if !ok {
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t.Fatal("cgoLookupHost ok=false")
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}
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if err != nil {
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t.Fatalf("cgoLookupHost: %v", err)
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}
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// cgoLookupHost need not return IPv4 before IPv6 in general,
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// but for the current implementation it does.
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// If that changes, this test will need updating.
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if len(addrs) < 1 || strings.Count(addrs[0], ".") != 3 || !strings.Contains(addrs[len(addrs)-1], "::") {
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t.Fatalf("cgoLookupHost google.com = %v, want IPv4 and IPv6", addrs)
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}
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}
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func TestPseudoCgoLookupIP(t *testing.T) {
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ips, err, ok := cgoLookupIP(context.Background(), "ip", "google.com")
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t.Logf("cgoLookupIP google.com: %v %v %v", ips, err, ok)
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if !ok {
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t.Fatal("cgoLookupIP ok=false")
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}
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if err != nil {
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t.Fatalf("cgoLookupIP: %v", err)
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}
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// cgoLookupIP need not return IPv4 before IPv6 in general,
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// but for the current implementation it does.
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// If that changes, this test will need updating.
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if len(ips) < 1 || len(ips[0].IP) != 4 || len(ips[len(ips)-1].IP) != 16 {
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t.Fatalf("cgoLookupIP google.com = %v, want IPv4 and IPv6", ips)
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}
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}
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func TestPseudoCgoLookupCNAME(t *testing.T) {
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t.Skip("res_search on macOS hangs in TypeCNAME queries (even in plain C programs)")
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cname, err, ok := cgoLookupCNAME(context.Background(), "redirect.swtch.com")
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t.Logf("cgoLookupCNAME redirect.swtch.com: %v %v %v", cname, err, ok)
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if !ok {
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t.Fatal("cgoLookupCNAME ok=false")
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}
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if err != nil {
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t.Fatalf("cgoLookupCNAME: %v", err)
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}
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if !strings.HasSuffix(cname, ".com") {
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t.Fatalf("cgoLookupCNAME redirect.swtch.com = %v, want *.com", cname)
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}
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}
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func TestPseudoCgoLookupPTR(t *testing.T) {
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t.Skip("res_search on macOS does not support TypePTR")
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ptrs, err, ok := cgoLookupPTR(context.Background(), "8.8.8.8")
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t.Logf("cgoLookupPTR 8.8.8.8: %v %v %v", ptrs, err, ok)
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if !ok {
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t.Fatal("cgoLookupPTR ok=false")
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}
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if err != nil {
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t.Fatalf("cgoLookupPTR: %v", err)
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}
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if len(ptrs) < 1 || ptrs[0] != "google-public-dns-a.google.com" {
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t.Fatalf("cgoLookupPTR = %v, want google-public-dns-a.google.com", ptrs)
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}
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}
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@ -3,7 +3,6 @@
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// license that can be found in the LICENSE file.
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// +build !cgo netgo
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// +build !darwin
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package net
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@ -70,11 +70,6 @@ func initConfVal() {
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// their own DNS requests. So always use cgo instead, which
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// avoids that.
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if runtime.GOOS == "darwin" {
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// Normally we force netGo to be true if building without cgo enabled.
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// On Darwin, we can call libc even if cgo is not enabled, so only set netGo to true
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// if explicitly requested.
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confVal.netGo = dnsMode == "go"
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confVal.forceCgoLookupHost = true
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return
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}
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@ -1,35 +0,0 @@
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// Copyright 2019 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 runtime
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import (
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"unsafe"
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)
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//go:linkname res_init net.res_init
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//go:nosplit
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//go:cgo_unsafe_args
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func res_init() int32 {
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return libcCall(unsafe.Pointer(funcPC(res_init_trampoline)), nil)
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}
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func res_init_trampoline()
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//go:linkname res_search net.res_search
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//go:nosplit
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//go:cgo_unsafe_args
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func res_search(dname *byte, class int32, rtype int32, answer *byte, anslen int32) (int32, int32) {
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args := struct {
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dname *byte
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class, rtype int32
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answer *byte
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anslen, retSize, retErr int32
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}{dname, class, rtype, answer, anslen, 0, 0}
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libcCall(unsafe.Pointer(funcPC(res_search_trampoline)), unsafe.Pointer(&args))
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return args.retSize, args.retErr
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}
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func res_search_trampoline()
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//go:cgo_import_dynamic libc_res_search res_search "/usr/lib/libSystem.B.dylib"
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//go:cgo_import_dynamic libc_res_init res_init "/usr/lib/libSystem.B.dylib"
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@ -1,50 +0,0 @@
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// Copyright 2019 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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|
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#include "go_asm.h"
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#include "go_tls.h"
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#include "textflag.h"
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TEXT runtime·res_init_trampoline(SB),NOSPLIT,$0
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PUSHL BP
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MOVL SP, BP
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SUBL $8, SP
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CALL libc_res_init(SB)
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CMPL AX, $-1
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JNE ok
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CALL libc_error(SB)
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ok:
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MOVL BP, SP
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POPL BP
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RET
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TEXT runtime·res_search_trampoline(SB),NOSPLIT,$0
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PUSHL BP
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MOVL SP, BP
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SUBL $24, SP
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MOVL 32(SP), CX
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MOVL 16(CX), AX // arg 5 anslen
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MOVL AX, 16(SP)
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MOVL 12(CX), AX // arg 4 answer
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MOVL AX, 12(SP)
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MOVL 8(CX), AX // arg 3 type
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MOVL AX, 8(SP)
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MOVL 4(CX), AX // arg 2 class
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MOVL AX, 4(SP)
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MOVL 0(CX), AX // arg 1 name
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MOVL AX, 0(SP)
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CALL libc_res_search(SB)
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XORL DX, DX
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CMPL AX, $-1
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JNE ok
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CALL libc_error(SB)
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MOVL (AX), DX
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XORL AX, AX
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ok:
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MOVL 32(SP), CX
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MOVL AX, 20(CX)
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MOVL DX, 24(CX)
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MOVL BP, SP
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POPL BP
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RET
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@ -1,40 +0,0 @@
|
||||
// Copyright 2019 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
#include "go_asm.h"
|
||||
#include "go_tls.h"
|
||||
#include "textflag.h"
|
||||
|
||||
TEXT runtime·res_init_trampoline(SB),NOSPLIT,$0
|
||||
PUSHQ BP
|
||||
MOVQ SP, BP
|
||||
CALL libc_res_init(SB)
|
||||
CMPL AX, $-1
|
||||
JNE ok
|
||||
CALL libc_error(SB)
|
||||
ok:
|
||||
POPQ BP
|
||||
RET
|
||||
|
||||
TEXT runtime·res_search_trampoline(SB),NOSPLIT,$0
|
||||
PUSHQ BP
|
||||
MOVQ SP, BP
|
||||
MOVQ DI, BX // move DI into BX to preserve struct addr
|
||||
MOVL 24(BX), R8 // arg 5 anslen
|
||||
MOVQ 16(BX), CX // arg 4 answer
|
||||
MOVL 12(BX), DX // arg 3 type
|
||||
MOVL 8(BX), SI // arg 2 class
|
||||
MOVQ 0(BX), DI // arg 1 name
|
||||
CALL libc_res_search(SB)
|
||||
XORL DX, DX
|
||||
CMPL AX, $-1
|
||||
JNE ok
|
||||
CALL libc_error(SB)
|
||||
MOVLQSX (AX), DX // move return from libc_error into DX
|
||||
XORL AX, AX // size on error is 0
|
||||
ok:
|
||||
MOVL AX, 28(BX) // size
|
||||
MOVL DX, 32(BX) // error code
|
||||
POPQ BP
|
||||
RET
|
||||
@ -1,25 +0,0 @@
|
||||
// Copyright 2015 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// System calls and other sys.stuff for ARM64, Darwin
|
||||
// System calls are implemented in libSystem, this file contains
|
||||
// trampolines that convert from Go to C calling convention.
|
||||
|
||||
#include "go_asm.h"
|
||||
#include "go_tls.h"
|
||||
#include "textflag.h"
|
||||
|
||||
// On darwin/arm, the runtime always uses runtime/cgo
|
||||
// for resolution. This will just exit with a nominal
|
||||
// exit code.
|
||||
|
||||
TEXT runtime·res_search_trampoline(SB),NOSPLIT,$0
|
||||
MOVW $90, R0
|
||||
BL libc_exit(SB)
|
||||
RET
|
||||
|
||||
TEXT runtime·res_init_trampoline(SB),NOSPLIT,$0
|
||||
MOVW $91, R0
|
||||
BL libc_exit(SB)
|
||||
RET
|
||||
@ -1,21 +0,0 @@
|
||||
// Copyright 2019 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
#include "go_asm.h"
|
||||
#include "go_tls.h"
|
||||
#include "textflag.h"
|
||||
|
||||
// On darwin/arm, the runtime always uses runtime/cgo
|
||||
// for resolution. This will just exit with a nominal
|
||||
// exit code.
|
||||
|
||||
TEXT runtime·res_search_trampoline(SB),NOSPLIT,$0
|
||||
MOVW $90, R0
|
||||
BL libc_exit(SB)
|
||||
RET
|
||||
|
||||
TEXT runtime·res_init_trampoline(SB),NOSPLIT,$0
|
||||
MOVW $91, R0
|
||||
BL libc_exit(SB)
|
||||
RET
|
||||
Loading…
Reference in New Issue
Block a user