net: return cname in LookupHost

Fixes #1395.

R=adg
CC=golang-dev
https://golang.org/cl/4036044

diff --git a/src/pkg/net/dnsclient.go b/src/pkg/net/dnsclient.go
index 87d76261f8e99e78c86b3e76ff5a8932c12f4698..3252dd454068e9c3e9e45e5e18d26d6faad12935 100644 (file)
--- a/src/pkg/net/dnsclient.go
+++ b/src/pkg/net/dnsclient.go
@@ -98,18 +98,18 @@ func exchange(cfg *dnsConfig, c Conn, name string, qtype uint16) (*dnsMsg, os.Er
 
 // Find answer for name in dns message.
 // On return, if err == nil, addrs != nil.
-func answer(name, server string, dns *dnsMsg, qtype uint16) (addrs []dnsRR, err os.Error) {
+func answer(name, server string, dns *dnsMsg, qtype uint16) (cname string, addrs []dnsRR, err os.Error) {
        addrs = make([]dnsRR, 0, len(dns.answer))
 
        if dns.rcode == dnsRcodeNameError && dns.recursion_available {
-               return nil, &DNSError{Error: noSuchHost, Name: name}
+               return "", nil, &DNSError{Error: noSuchHost, Name: name}
        }
        if dns.rcode != dnsRcodeSuccess {
                // None of the error codes make sense
                // for the query we sent.  If we didn't get
                // a name error and we didn't get success,
                // the server is behaving incorrectly.
-               return nil, &DNSError{Error: "server misbehaving", Name: name, Server: server}
+               return "", nil, &DNSError{Error: "server misbehaving", Name: name, Server: server}
        }
 
        // Look for the name.
@@ -137,19 +137,19 @@ Cname:
                        }
                }
                if len(addrs) == 0 {
-                       return nil, &DNSError{Error: noSuchHost, Name: name, Server: server}
+                       return "", nil, &DNSError{Error: noSuchHost, Name: name, Server: server}
                }
-               return addrs, nil
+               return name, addrs, nil
        }
 
-       return nil, &DNSError{Error: "too many redirects", Name: name, Server: server}
+       return "", nil, &DNSError{Error: "too many redirects", Name: name, Server: server}
 }
 
 // Do a lookup for a single name, which must be rooted
 // (otherwise answer will not find the answers).
-func tryOneName(cfg *dnsConfig, name string, qtype uint16) (addrs []dnsRR, err os.Error) {
+func tryOneName(cfg *dnsConfig, name string, qtype uint16) (cname string, addrs []dnsRR, err os.Error) {
        if len(cfg.servers) == 0 {
-               return nil, &DNSError{Error: "no DNS servers", Name: name}
+               return "", nil, &DNSError{Error: "no DNS servers", Name: name}
        }
        for i := 0; i < len(cfg.servers); i++ {
                // Calling Dial here is scary -- we have to be sure
@@ -170,7 +170,7 @@ func tryOneName(cfg *dnsConfig, name string, qtype uint16) (addrs []dnsRR, err o
                        err = merr
                        continue
                }
-               addrs, err = answer(name, server, msg, qtype)
+               cname, addrs, err = answer(name, server, msg, qtype)
                if err == nil || err.(*DNSError).Error == noSuchHost {
                        break
                }
@@ -261,9 +261,8 @@ func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err os.Erro
                        rname += "."
                }
                // Can try as ordinary name.
-               addrs, err = tryOneName(cfg, rname, qtype)
+               cname, addrs, err = tryOneName(cfg, rname, qtype)
                if err == nil {
-                       cname = rname
                        return
                }
        }
@@ -277,9 +276,8 @@ func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err os.Erro
                if rname[len(rname)-1] != '.' {
                        rname += "."
                }
-               addrs, err = tryOneName(cfg, rname, qtype)
+               cname, addrs, err = tryOneName(cfg, rname, qtype)
                if err == nil {
-                       cname = rname
                        return
                }
        }
@@ -289,9 +287,8 @@ func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err os.Erro
        if !rooted {
                rname += "."
        }
-       addrs, err = tryOneName(cfg, rname, qtype)
+       cname, addrs, err = tryOneName(cfg, rname, qtype)
        if err == nil {
-               cname = rname
                return
        }
        return