gluster: IPv6 single stack support

Summary:
- This diff changes all locations in the code to prefer inet6 family
  instead of inet.  This will allow change GlusterFS to operate
  via IPv6 instead of IPv4 for all internal operations while still
  being able to serve (FUSE or NFS) clients via IPv4.
- The changes apply to NFS as well.
- This diff ports D1892990, D1897341 & D1896522 to the 3.8 branch.

Test Plan: Prove tests!

Reviewers: dph, rwareing

Signed-off-by: Shreyas Siravara <sshreyas@fb.com>

Change-Id: I34fdaaeb33c194782255625e00616faf75d60c33
Reviewed-on: http://review.gluster.org/16059
Reviewed-by: Shreyas Siravara <sshreyas@fb.com>
Tested-by: Shreyas Siravara <sshreyas@fb.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

2 files changed, 18 insertions, 14 deletions

diff --git a/libglusterfs/src/common-utils.c b/libglusterfs/src/common-utils.c
index 18f445ae265..6a5889207d4 100644
--- a/libglusterfs/src/common-utils.c
+++ b/libglusterfs/src/common-utils.c
@@ -181,26 +181,16 @@ gf_rev_dns_lookup (const char *ip)
 {
         char               *fqdn = NULL;
         int                ret  = 0;
-        struct sockaddr_in sa   = {0};
-        char               host_addr[256] = {0, };
 
         GF_VALIDATE_OR_GOTO ("resolver", ip, out);
 
-        sa.sin_family = AF_INET;
-        inet_pton (AF_INET, ip, &sa.sin_addr);
-        ret = getnameinfo ((struct sockaddr *)&sa, sizeof (sa), host_addr,
-                          sizeof (host_addr), NULL, 0, 0);
-
+        /* Get the FQDN */
+        ret =  gf_get_hostname_from_ip ((char *)ip, &fqdn);
         if (ret != 0) {
                 gf_msg ("resolver", GF_LOG_INFO, errno,
                         LG_MSG_RESOLVE_HOSTNAME_FAILED, "could not resolve "
                         "hostname for %s", ip);
-                goto out;
         }
-
-        /* Get the FQDN */
-        fqdn = gf_strdup (host_addr);
-
 out:
        return fqdn;
 }
@@ -3107,11 +3097,13 @@ gf_get_hostname_from_ip (char *client_ip, char **hostname)
         char                    *client_ip_copy               = NULL;
         char                    *tmp                          = NULL;
         char                    *ip                           = NULL;
+        size_t                   addr_sz                      = 0;
 
         /* if ipv4, reverse lookup the hostname to
          * allow FQDN based rpc authentication
          */
-        if (valid_ipv4_address (client_ip, strlen (client_ip), 0) == _gf_false) {
+        if (!valid_ipv6_address (client_ip, strlen (client_ip), 0) &&
+            !valid_ipv4_address (client_ip, strlen (client_ip), 0)) {
                 /* most times, we get a.b.c.d:port form, so check that */
                 client_ip_copy = gf_strdup (client_ip);
                 if (!client_ip_copy)
@@ -3124,12 +3116,14 @@ gf_get_hostname_from_ip (char *client_ip, char **hostname)
 
         if (valid_ipv4_address (ip, strlen (ip), 0) == _gf_true) {
                 client_sockaddr = (struct sockaddr *)&client_sock_in;
+                addr_sz = sizeof (client_sock_in);
                 client_sock_in.sin_family = AF_INET;
                 ret = inet_pton (AF_INET, ip,
                                  (void *)&client_sock_in.sin_addr.s_addr);
 
         } else if (valid_ipv6_address (ip, strlen (ip), 0) == _gf_true) {
                 client_sockaddr = (struct sockaddr *) &client_sock_in6;
+                addr_sz = sizeof (client_sock_in6);
 
                 client_sock_in6.sin6_family = AF_INET6;
                 ret = inet_pton (AF_INET6, ip,
@@ -3143,8 +3137,14 @@ gf_get_hostname_from_ip (char *client_ip, char **hostname)
                 goto out;
         }
 
+        /* You cannot just use sizeof (*client_sockaddr), as per the man page
+         * the (getnameinfo) size must be the size of the underlying sockaddr
+         * struct e.g. sockaddr_in6 or sockaddr_in.  Failure to do so will
+         * break IPv6 hostname resolution (IPv4 will work only because
+         * the sockaddr_in struct happens to be of the correct size).
+         */
         ret = getnameinfo (client_sockaddr,
-                           sizeof (*client_sockaddr),
+                           addr_sz,
                            client_hostname, sizeof (client_hostname),
                            NULL, 0, 0);
         if (ret) {
diff --git a/libglusterfs/src/compat.h b/libglusterfs/src/compat.h
index 69adfbcd7fe..33388598b1e 100644
--- a/libglusterfs/src/compat.h
+++ b/libglusterfs/src/compat.h
@@ -463,6 +463,8 @@ int gf_mkostemp (char *tmpl, int suffixlen, int flags);
 #define ST_CTIM_NSEC_SET(stbuf, val) do { } while (0);
 #endif
 
+#ifndef IPV6_DEFAULT
+
 #ifndef IXDR_GET_LONG
 #define IXDR_GET_LONG(buf) ((long)IXDR_GET_U_INT32(buf))
 #endif
@@ -479,6 +481,8 @@ int gf_mkostemp (char *tmpl, int suffixlen, int flags);
 #define IXDR_PUT_U_LONG(buf, v)       IXDR_PUT_LONG(buf, (long)(v))
 #endif
 
+#endif /* IPV6_DEFAULT */
+
 #if defined(__GNUC__) && !defined(RELAX_POISONING)
 /* Use run API, see run.h */
 #include <stdlib.h> /* system(), mkostemp() */