Re: unrecognized getnameinfo() bugs dealing with IPv4-mapped addresses

[Joe Orton]

On Tue, May 18, 2004 at 04:58:14PM -0400, Jeff Trawick wrote:
> Previously we went through this mess on older Mac OS X (DNS queries only?)
> 
> I just realized that the glibc shipping with RHAS 2.1 and 3.0 (and surely 
> many other Linux distros) has a problem with getnameinfo() for IPv4-mapped 
> address for something defined in host file but not in DNS.

I'll file a bug on that if you haven't already.

> The configure check for this condition fails to note the problem because 
> (at least in my environments) the DNS has a mapping for 
> 127.0.0.1->localhost.
> 
> Shall we just assume that the GETNAMEINFO_IPV4_MAPPED_FAILS logic can be 
> used on all platforms (incurring the minor overhead), instead of trying to 
> be clever?

Sounds very sensible.  The code can be simplified to avoid a pointer
dereference too...

--- network_io/unix/sockaddr.c  4 Mar 2004 16:17:25 -0000       1.49
+++ network_io/unix/sockaddr.c  19 May 2004 09:19:07 -0000
@@ -575,27 +575,24 @@
      * a numeric address string if it fails to resolve the host name;
      * that is *not* what we want here
      *
-     * Additionally, if we know getnameinfo() doesn't handle IPv4-mapped
-     * IPv6 addresses correctly, drop down to IPv4 before calling
-     * getnameinfo().
+     * For IPv4-mapped IPv6 addresses, drop down to IPv4 before calling
+     * getnameinfo() to avoid getnameinfo bugs (MacOS X, glibc).
      */
-#ifdef GETNAMEINFO_IPV4_MAPPED_FAILS
     if (sockaddr->family == AF_INET6 &&
         IN6_IS_ADDR_V4MAPPED(&sockaddr->sa.sin6.sin6_addr)) {
-        struct apr_sockaddr_t tmpsa;
-        tmpsa.sa.sin.sin_family = AF_INET;
-        tmpsa.sa.sin.sin_addr.s_addr = ((uint32_t *)sockaddr->ipaddr_ptr)[3];
+        struct sockaddr_in tmpsa;
+        tmpsa.sin_family = AF_INET;
+        tmpsa.sin_addr.s_addr = sockaddr->sa.sin6.sin6_addr.s6_addr[3];
 
-        rc = getnameinfo((const struct sockaddr *)&tmpsa.sa,
-                         sizeof(struct sockaddr_in),
+        rc = getnameinfo((const struct sockaddr *)&tmpsa, sizeof(tmpsa),
                          tmphostname, sizeof(tmphostname), NULL, 0,
                          flags != 0 ? flags : NI_NAMEREQD);
     }
     else
-#endif
-    rc = getnameinfo((const struct sockaddr *)&sockaddr->sa, sockaddr->salen,
-                     tmphostname, sizeof(tmphostname), NULL, 0,
-                     flags != 0 ? flags : NI_NAMEREQD);
+        rc = getnameinfo((const struct sockaddr *)&sockaddr->sa, 
sockaddr->salen,
+                         tmphostname, sizeof(tmphostname), NULL, 0,
+                         flags != 0 ? flags : NI_NAMEREQD);
+
     if (rc != 0) {
         *hostname = NULL;