nlm: Fix error messages for failed remote rpcbind contact

In case of a remote rpcbind connection timeout,
the NFS kernel lock manager emits an error message
along the lines of:

    NLM: failed to contact remote rpcbind, stat = 5, port = 28416

In the Bugzilla PR, Garrett Wollman identified the following problems
with that error message:

- The error is in decimal, which can only be deciphered by reading the
  source code.
- The port number is byte-swapped.
- The error message does not identify the client the NLM is trying to
  communicate with.

Fix the shortcomings of the current error message by:

- Printing out the port number correctly.
- Mentioning the remote client.

The low-level decimal error remains an outstanding issue though.
It seems like the error strings describing the error codes live outside
of the kernel code currently.

PR:		244698
Reported by:	wollman
Approved by:	allanjude
Sponsored by:	National Bureau of Economic Research
Sponsored by:	Klara, Inc.
Co-authored-by:	Mateusz Piotrowski <0mp@FreeBSD.org>

1 files changed, 26 insertions, 2 deletions

diff --git a/sys/nlm/nlm_prot_impl.c b/sys/nlm/nlm_prot_impl.c
index a5b917b07f8b..216c4ac82b53 100644
--- a/sys/nlm/nlm_prot_impl.c
+++ b/sys/nlm/nlm_prot_impl.c
@@ -343,6 +343,12 @@ nlm_get_rpc(struct sockaddr *sa, rpcprog_t prog, rpcvers_t vers)
 	bool_t tryagain = FALSE;
 	struct portmap mapping;
 	u_short port = 0;
+	struct sockaddr_in *sin4;
+	char namebuf[INET_ADDRSTRLEN];
+#ifdef INET6
+	struct sockaddr_in6 *sin6;
+	char namebuf6[INET6_ADDRSTRLEN];
+#endif
 
 	/*
 	 * First we need to contact the remote RPCBIND service to find
@@ -489,8 +495,26 @@ again:
 		}
 
 		/* Otherwise, bad news. */
-		NLM_ERR("NLM: failed to contact remote rpcbind, "
-		    "stat = %d, port = %d\n", (int) stat, port);
+		switch (ss.ss_family) {
+			case AF_INET:
+				sin4 = (struct sockaddr_in *)&ss;
+				inet_ntop(ss.ss_family, &sin4->sin_addr,
+				    namebuf, sizeof namebuf);
+				NLM_ERR("NLM: failed to contact remote rpcbind, "
+				    "stat = %d, host = %s, port = %d\n",
+				    (int) stat, namebuf, htons(port));
+				break;
+#ifdef INET6
+			case AF_INET6:
+				sin6 = (struct sockaddr_in6 *)&ss;
+				inet_ntop(ss.ss_family, &sin6->sin6_addr,
+				    namebuf6, sizeof namebuf6);
+				NLM_ERR("NLM: failed to contact remote rpcbind, "
+				    "stat = %d, host = %s, port = %d\n",
+				    (int) stat, namebuf6, htons(port));
+				break;
+#endif
+		}
 		CLNT_DESTROY(rpcb);
 		return (NULL);
 	}