id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
8503,Cannot connect to localhost without global connectivity,Edward@…,chris_kohlhoff,"On Windows, if there are no network cards installed or they are all disabled, attempts to resolve localhost fail. The problem is that by default, the default value for the basic_resolver_query constructor's resolve_flags parameter is address_configured, which is AI_ADDRCONFIG on Windows. However, as implemented AI_ADDRCONFIG is actually detrimental, particularly for resolution of loopback and link-local addresses.

The rationale from the Google Chrome source code explains this. Here is the relevant snippet from !SystemHostResolverCall in [http://src.chromium.org/viewvc/chrome/trunk/src/net/dns/host_resolver_proc.cc host_resolver_proc.cc]:

{{{
#if defined(OS_WIN)
  // DO NOT USE AI_ADDRCONFIG ON WINDOWS.
  //
  // The following comment in <winsock2.h> is the best documentation I found
  // on AI_ADDRCONFIG for Windows:
  //   Flags used in ""hints"" argument to getaddrinfo()
  //       - AI_ADDRCONFIG is supported starting with Vista
  //       - default is AI_ADDRCONFIG ON whether the flag is set or not
  //         because the performance penalty in not having ADDRCONFIG in
  //         the multi-protocol stack environment is severe;
  //         this defaulting may be disabled by specifying the AI_ALL flag,
  //         in that case AI_ADDRCONFIG must be EXPLICITLY specified to
  //         enable ADDRCONFIG behavior
  //
  // Not only is AI_ADDRCONFIG unnecessary, but it can be harmful.  If the
  // computer is not connected to a network, AI_ADDRCONFIG causes getaddrinfo
  // to fail with WSANO_DATA (11004) for ""localhost"", probably because of the
  // following note on AI_ADDRCONFIG in the MSDN getaddrinfo page:
  //   The IPv4 or IPv6 loopback address is not considered a valid global
  //   address.
  // See http://crbug.com/5234.
  //
  // OpenBSD does not support it, either.
  hints.ai_flags = 0;
#else
  hints.ai_flags = AI_ADDRCONFIG;
#endif
}}}

The developers of [http://xcb.freedesktop.org/ XCB] arrived at a similar conclusion. See their discussion on [http://thread.gmane.org/gmane.comp.freedesktop.xcb/6973 Bug: Can’t connect to localhost without global connectivity].

Code using ASIO can work around this problem, but doing so would require platform-specific code and intricate knowledge of poorly documented platform-specific behavior.",Bugs,closed,To Be Determined,asio,Boost 1.53.0,Problem,invalid,localhost AI_ADDRCONFIG,