net: do not set V4MAPPED on FreeBSD

V4MAPPED is not supported on recent FreeBSD versions, at least on 10.1.
Thus, do not set this flag in net.connect on FreeBSD.

Fixes: nodejs/node-v0.x-archive#8540
Fixes: nodejs/node-v0.x-archive#9204
PR-URL: nodejs/node-v0.x-archive#18204
PR-URL: nodejs#1555
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

doc/api/dns.markdown

@@ -267,8 +267,9 @@ The following flags can be passed as hints to `dns.lookup`.
 of addresses supported by the current system. For example, IPv4 addresses
 are only returned if the current system has at least one IPv4 address
 configured. Loopback addresses are not considered.
-- `dns.V4MAPPED`: If the IPv6 family was specified, but no IPv6 addresses
-were found, then return IPv4 mapped IPv6 addresses.
+- `dns.V4MAPPED`: If the IPv6 family was specified, but no IPv6 addresses were
+found, then return IPv4 mapped IPv6 addresses. Note that it is not supported
+on some operating systems (e.g FreeBSD 10.1).
 
 ## Implementation considerations
 

lib/net.js

@@ -936,8 +936,16 @@ function lookupAndConnect(self, options) {
     hints: 0
   };
 
-  if (dnsopts.family !== 4 && dnsopts.family !== 6)
-    dnsopts.hints = dns.ADDRCONFIG | dns.V4MAPPED;
+  if (dnsopts.family !== 4 && dnsopts.family !== 6) {
+    dnsopts.hints = dns.ADDRCONFIG;
+    // The AI_V4MAPPED hint is not supported on FreeBSD, and getaddrinfo
+    // returns EAI_BADFLAGS. However, it seems to be supported on most other
+    // systems. See
+    // http://lists.freebsd.org/pipermail/freebsd-bugs/2008-February/028260.html
+    // for more information on the lack of support for FreeBSD.
+    if (process.platform !== 'freebsd')
+      dnsopts.hints |= dns.V4MAPPED;
+  }
 
   debug('connect: find host ' + host);
   debug('connect: dns options ' + dnsopts);