SUNRPC: create API for getting remote peer address

Provide an API for retrieving the remote peer address without allowing
direct access to the rpc_xprt struct.

Test-plan:
Compile kernel with CONFIG_NFS enabled.

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

2 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 2e68ac0aa022..65196b03f0ab 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -123,6 +123,7 @@ void		rpc_setbufsize(struct rpc_clnt *, unsigned int, unsigned int);
 size_t          rpc_max_payload(struct rpc_clnt *);
 void            rpc_force_rebind(struct rpc_clnt *);
 int             rpc_ping(struct rpc_clnt *clnt, int flags);
+size_t          rpc_peeraddr(struct rpc_clnt *, struct sockaddr *, size_t);
 
 /*
  * Helper function for NFSroot support
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index d003c2f5688f..94768cf5fd5b 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -533,6 +533,27 @@ rpc_call_setup(struct rpc_task *task, struct rpc_message *msg, int flags)
                 task->tk_action = rpc_exit_task;
 }
 
+/**
+ * rpc_peeraddr - extract remote peer address from clnt's xprt
+ * @clnt: RPC client structure
+ * @buf: target buffer
+ * @size: length of target buffer
+ *
+ * Returns the number of bytes that are actually in the stored address.
+ */
+size_t rpc_peeraddr(struct rpc_clnt *clnt, struct sockaddr *buf, size_t bufsize)
+{
+        size_t bytes;
+        struct rpc_xprt *xprt = clnt->cl_xprt;
+
+        bytes = sizeof(xprt->addr);
+        if (bytes > bufsize)
+                bytes = bufsize;
+        memcpy(buf, &clnt->cl_xprt->addr, bytes);
+        return sizeof(xprt->addr);
+}
+EXPORT_SYMBOL(rpc_peeraddr);
+
 void
 rpc_setbufsize(struct rpc_clnt *clnt, unsigned int sndsize, unsigned int rcvsize)
 {