mount: getport: don't use getaddrinfo(3) on old systems

Older glibc versions have a getaddrinfo(3) that doesn't support
AI_ADDRCONFIG.  Detect that case and build something else for
getport.c that will work adequately on those systems.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/support/nfs/getport.c b/support/nfs/getport.c
index 25dca6c0a9da38372332df67a0c057d49f280f2e..47824a24e5a969410cad9424206d927eafbf1bd9 100644 (file)
--- a/support/nfs/getport.c
+++ b/support/nfs/getport.c
@@ -73,6 +73,60 @@ static const char *nfs_gp_rpcb_pgmtbl[] = {
        NULL,
 };
 
+#ifdef HAVE_DECL_AI_ADDRCONFIG
+/*
+ * getaddrinfo(3) generates a usable loopback address based on how the
+ * local network interfaces are configured.  RFC 3484 requires that the
+ * results are sorted so that the first result has the best likelihood
+ * of working, so we try just that first result.
+ *
+ * Returns TRUE on success.
+ */
+static int nfs_gp_loopback_address(struct sockaddr *sap, socklen_t *salen)
+{
+       struct addrinfo *gai_results;
+       struct addrinfo gai_hint = {
+               .ai_flags       = AI_ADDRCONFIG,
+       };
+       socklen_t len = *salen;
+       int ret = 0;
+
+       if (getaddrinfo(NULL, "sunrpc", &gai_hint, &gai_results))
+               return 0;
+
+       switch (gai_results->ai_addr->sa_family) {
+       case AF_INET:
+       case AF_INET6:
+               if (len >= gai_results->ai_addrlen) {
+                       memcpy(sap, gai_results->ai_addr,
+                                       gai_results->ai_addrlen);
+                       *salen = gai_results->ai_addrlen;
+                       ret = 1;
+               }
+       }
+
+       freeaddrinfo(gai_results);
+       return ret;
+}
+#else
+/*
+ * Old versions of getaddrinfo(3) don't support AI_ADDRCONFIG, so we
+ * have a fallback for building on legacy systems.
+ */
+static int nfs_gp_loopback_address(struct sockaddr *sap, socklen_t *salen)
+{
+       struct sockaddr_in *sin = (struct sockaddr_in *)sap;
+
+       memset(sin, 0, sizeof(*sin));
+
+       sin->sin_family = AF_INET;
+       sin->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+       *salen = sizeof(*sin);
+
+       return 1;
+}
+#endif
+
 /*
  * Discover the port number that should be used to contact an
  * rpcbind service.  This will detect if the port has a local
@@ -780,12 +834,10 @@ unsigned short nfs_getlocalport(const rpcprot_t program,
                                const rpcvers_t version,
                                const unsigned short protocol)
 {
-       struct addrinfo *gai_results;
-       struct addrinfo gai_hint = {
-               .ai_flags       = AI_ADDRCONFIG,
-       };
+       struct sockaddr_storage address;
+       struct sockaddr *lb_addr = (struct sockaddr *)&address;
+       socklen_t lb_len = sizeof(lb_addr);
        unsigned short port = 0;
-       int error;
 
 #ifdef NFS_GP_LOCAL
        const struct sockaddr_un sun = {
@@ -811,12 +863,9 @@ unsigned short nfs_getlocalport(const rpcprot_t program,
 #endif /* NFS_GP_LOCAL */
 
        if (port == 0) {
-               error = getaddrinfo(NULL, "sunrpc", &gai_hint, &gai_results);
-               if (error == 0) {
-                       port = nfs_getport(gai_results->ai_addr,
-                                               gai_results->ai_addrlen,
+               if (nfs_gp_loopback_address(lb_addr, &lb_len)) {
+                       port = nfs_getport(lb_addr, lb_len,
                                                program, version, protocol);
-                       freeaddrinfo(gai_results);
                } else
                        rpc_createerr.cf_stat = RPC_UNKNOWNADDR;
        }