sm-notify: Support creating a PF_INET6 socket in smn_create_socket()

Socket creation is unfortunately complicated by the need to handle the
case where sm-notify is built with IPv6 support, but the local system
has disabled it entirely at run-time (ie, socket(3) returns
EAFNOSUPPORT when we try to create an AF_INET6 socket).

The run-time address family setting is made available in the global
variable nsm_family.  This setting can control the family of the
socket's bind address and what kind of addresses we want returned by
smn_lookup().  Support for that is added in subsequent patches.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/utils/statd/sm-notify.c b/utils/statd/sm-notify.c
index 462ba7987fef96036ba79f7662694787e37fac76..0ba817a431a225cab45ab083d62688780b449af5 100644 (file)
--- a/utils/statd/sm-notify.c
+++ b/utils/statd/sm-notify.c
@@ -49,6 +49,7 @@ struct nsm_host {
 
 static char            nsm_hostname[256];
 static int             nsm_state;
+static int             nsm_family = AF_INET;
 static int             opt_debug = 0;
 static _Bool           opt_update_state = true;
 static unsigned int    opt_max_retry = 15 * 60;
@@ -141,6 +142,79 @@ smn_get_host(const char *hostname,
        return 1;
 }
 
+#ifdef IPV6_SUPPORTED
+static int smn_socket(void)
+{
+       int sock;
+
+       /*
+        * Use an AF_INET socket if IPv6 is disabled on the
+        * local system.
+        */
+       sock = socket(AF_INET6, SOCK_DGRAM, 0);
+       if (sock == -1) {
+               if (errno != EAFNOSUPPORT) {
+                       xlog(L_ERROR, "Failed to create RPC socket: %m");
+                       return -1;
+               }
+               sock = socket(AF_INET, SOCK_DGRAM, 0);
+               if (sock < 0) {
+                       xlog(L_ERROR, "Failed to create RPC socket: %m");
+                       return -1;
+               }
+       } else
+               nsm_family = AF_INET6;
+
+       if (fcntl(sock, F_SETFL, O_NONBLOCK) == -1) {
+               xlog(L_ERROR, "fcntl(3) on RPC socket failed: %m");
+               goto out_close;
+       }
+
+       /*
+        * TI-RPC over IPv6 (udp6/tcp6) does not handle IPv4.  However,
+        * since sm-notify open-codes all of its RPC support, it can
+        * use a single socket and let the local network stack provide
+        * the correct mapping between address families automatically.
+        * This is the same thing that is done in the kernel.
+        */
+       if (nsm_family == AF_INET6) {
+               const int zero = 0;
+               socklen_t zerolen = (socklen_t)sizeof(zero);
+
+               if (setsockopt(sock, SOL_IPV6, IPV6_V6ONLY,
+                                       (char *)&zero, zerolen) == -1) {
+                       xlog(L_ERROR, "setsockopt(3) on RPC socket failed: %m");
+                       goto out_close;
+               }
+       }
+
+       return sock;
+
+out_close:
+       (void)close(sock);
+       return -1;
+}
+#else  /* !IPV6_SUPPORTED */
+static int smn_socket(void)
+{
+       int sock;
+
+       sock = socket(AF_INET, SOCK_DGRAM, 0);
+       if (sock == -1) {
+               xlog(L_ERROR, "Failed to create RPC socket: %m");
+               return -1;
+       }
+
+       if (fcntl(sock, F_SETFL, O_NONBLOCK) == -1) {
+               xlog(L_ERROR, "fcntl(3) on RPC socket failed: %m");
+               (void)close(sock);
+               return -1;
+       }
+
+       return sock;
+}
+#endif /* !IPV6_SUPPORTED */
+
 /*
  * Prepare a socket for sending RPC requests
  *
@@ -155,12 +229,9 @@ smn_create_socket(const char *srcaddr, const uint16_t srcport)
        int sock, retry_cnt = 0;
 
 retry:
-       sock = socket(AF_INET, SOCK_DGRAM, 0);
-       if (sock < 0) {
-               xlog(L_ERROR, "Failed to create RPC socket: %m");
+       sock = smn_socket();
+       if (sock == -1)
                return -1;
-       }
-       fcntl(sock, F_SETFL, O_NONBLOCK);
 
        memset(&address, 0, sizeof(address));
        local_addr->sa_family = AF_INET;        /* Default to IPv4 */