net: fix lookup of AAAA-only hosts without cgo

Fixes #3762.

R=rsc
CC=golang-dev
https://golang.org/cl/6303106

diff --git a/src/pkg/net/dnsclient_unix.go b/src/pkg/net/dnsclient_unix.go
index 18c39360e40454ad6302adf57f65e6cd0ab2c580..9e21bb4a0f66e9d28522f82b0e47d9562d3e3297 100644 (file)
--- a/src/pkg/net/dnsclient_unix.go
+++ b/src/pkg/net/dnsclient_unix.go
@@ -237,24 +237,30 @@ func goLookupIP(name string) (addrs []IP, err error) {
        }
        var records []dnsRR
        var cname string
-       cname, records, err = lookup(name, dnsTypeA)
-       if err != nil {
-               return
-       }
+       var err4, err6 error
+       cname, records, err4 = lookup(name, dnsTypeA)
        addrs = convertRR_A(records)
        if cname != "" {
                name = cname
        }
-       _, records, err = lookup(name, dnsTypeAAAA)
-       if err != nil && len(addrs) > 0 {
-               // Ignore error because A lookup succeeded.
-               err = nil
+       _, records, err6 = lookup(name, dnsTypeAAAA)
+       if err4 != nil && err6 == nil {
+               // Ignore A error because AAAA lookup succeeded.
+               err4 = nil
        }
-       if err != nil {
-               return
+       if err6 != nil && len(addrs) > 0 {
+               // Ignore AAAA error because A lookup succeeded.
+               err6 = nil
        }
+       if err4 != nil {
+               return nil, err4
+       }
+       if err6 != nil {
+               return nil, err6
+       }
+
        addrs = append(addrs, convertRR_AAAA(records)...)
-       return
+       return addrs, nil
 }
 
 // goLookupCNAME is the native Go implementation of LookupCNAME.