Revert "net: ensure that malformed domain names report a consistent error"

This reverts commit bb8c2e19.

Change-Id: I9bc089e9f2296805ef055b98e8c86ba73af30226
Reviewed-on: https://go-review.googlesource.com/18439Reviewed-by: Russ Cox <rsc@golang.org>

src/net/ip_test.go

@@ -540,48 +540,3 @@ func TestIPAddrScope(t *testing.T) {
 		}
 	}
 }
-
-func TestLookupBadName(t *testing.T) {
-	// Check that we get the same error for invalid names regardless of lookup algorithm.
-
-	mode := ""
-	check := func(fn string, err error) {
-		if e, ok := err.(*DNSError); !ok || e.Err != "invalid domain name" {
-			t.Errorf("%s: %s(\"!!!.local\") = %T(%v), want DNSError(invalid domain name)", mode, fn, err, err)
-		}
-	}
-
-	for i, fn := range []func() func(){forceGoDNS, forceCgoDNS} {
-		fixup := fn()
-		if fixup == nil {
-			continue
-		}
-		mode = "netgo"
-		if i == 1 {
-			mode = "netcgo"
-		}
-
-		_, err := LookupHost("!!!.local")
-		check("LookupHost", err)
-
-		_, err = LookupIP("!!!.local")
-		check("LookupIP", err)
-
-		_, err = LookupCNAME("!!!.local")
-		check("LookupCNAME", err)
-
-		_, _, err = LookupSRV("x", "tcp", "!!!.local")
-		check("LookupSRV", err)
-
-		_, err = LookupMX("!!!.local")
-		check("LookupMX", err)
-
-		_, err = LookupNS("!!!.local")
-		check("LookupNS", err)
-
-		_, err = LookupTXT("!!!.local")
-		check("LookupTXT", err)
-
-		fixup()
-	}
-}

src/net/lookup.go

@@ -33,9 +33,6 @@ func LookupHost(host string) (addrs []string, err error) {
 	if ip := ParseIP(host); ip != nil {
 		return []string{host}, nil
 	}
-	if !isDomainName(host) {
-		return nil, &DNSError{Err: "invalid domain name", Name: host}
-	}
 	return lookupHost(host)
 }
 
@@ -50,9 +47,6 @@ func LookupIP(host string) (ips []IP, err error) {
 	if ip := ParseIP(host); ip != nil {
 		return []IP{ip}, nil
 	}
-	if !isDomainName(host) {
-		return nil, &DNSError{Err: "invalid domain name", Name: host}
-	}
 	addrs, err := lookupIPMerge(host)
 	if err != nil {
 		return
@@ -152,9 +146,6 @@ func LookupPort(network, service string) (port int, err error) {
 // LookupHost or LookupIP directly; both take care of resolving
 // the canonical name as part of the lookup.
 func LookupCNAME(name string) (cname string, err error) {
-	if !isDomainName(name) {
-		return "", &DNSError{Err: "invalid domain name", Name: name}
-	}
 	return lookupCNAME(name)
 }
 
@@ -168,33 +159,21 @@ func LookupCNAME(name string) (cname string, err error) {
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
 func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
-	if !isDomainName(name) {
-		return "", nil, &DNSError{Err: "invalid domain name", Name: name}
-	}
 	return lookupSRV(service, proto, name)
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
 func LookupMX(name string) (mxs []*MX, err error) {
-	if !isDomainName(name) {
-		return nil, &DNSError{Err: "invalid domain name", Name: name}
-	}
 	return lookupMX(name)
 }
 
 // LookupNS returns the DNS NS records for the given domain name.
 func LookupNS(name string) (nss []*NS, err error) {
-	if !isDomainName(name) {
-		return nil, &DNSError{Err: "invalid domain name", Name: name}
-	}
 	return lookupNS(name)
 }
 
 // LookupTXT returns the DNS TXT records for the given domain name.
 func LookupTXT(name string) (txts []string, err error) {
-	if !isDomainName(name) {
-		return nil, &DNSError{Err: "invalid domain name", Name: name}
-	}
 	return lookupTXT(name)
 }