code review 4557058: net: name-based destination address selection

src/pkg/net/ipsock.go

 // Copyright 2009 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.
 
 // IP sockets
 
 package net
 
 import (
         "os"
@@ skipping 80 matching lines @@
                 }
         }
 
         if (laddr == nil || laddr.family() == syscall.AF_INET) &&
                 (raddr == nil || raddr.family() == syscall.AF_INET) {
                 return syscall.AF_INET
         }
         return syscall.AF_INET6
 }
 
-func firstFavoriteAddr(filter func(IP) IP, addrs []string) (addr IP) {
-        if filter == anyaddr {
-                // We'll take any IP address, but since the dialing code
-                // does not yet try multiple addresses, prefer to use
-                // an IPv4 address if possible.  This is especially relevant
-                // if localhost resolves to [ipv6-localhost, ipv4-localhost].
-                // Too much code assumes localhost == ipv4-localhost.
-                addr = firstSupportedAddr(ipv4only, addrs)
-                if addr == nil {
-                        addr = firstSupportedAddr(anyaddr, addrs)
-                }
-        } else {
-                addr = firstSupportedAddr(filter, addrs)
-        }
-        return
-}
-
 func firstSupportedAddr(filter func(IP) IP, addrs []string) IP {
         for _, s := range addrs {
                 if addr := filter(ParseIP(s)); addr != nil {
                         return addr
                 }
         }
         return nil
 }
 
 func anyaddr(x IP) IP {
@@ skipping 158 matching lines @@
                         }
                         if net != "" && net[len(net)-1] == '6' {
                                 filter = ipv6only
                         }
                         // Not an IP address.  Try as a DNS name.
                         addrs, err1 := LookupHost(host)
                         if err1 != nil {
                                 err = err1
                                 goto Error
                         }
-                        addr = firstFavoriteAddr(filter, addrs)
+                        addr = firstSupportedAddr(filter, addrs)
                         if addr == nil {
                                 // should not happen
                                 err = &AddrError{"LookupHost returned no suitable address", addrs[0]}
                                 goto Error
                         }
                 }
         }
 
         p, i, ok := dtoi(port, 0)
         if !ok || i != len(port) {
                 p, err = LookupPort(net, port)
                 if err != nil {
                         goto Error
                 }
         }
         if p < 0 || p > 0xFFFF {
                 err = &AddrError{"invalid port", port}
                 goto Error
         }
 
         return addr, p, nil
 
 Error:
         return nil, 0, err
 }