nbd: Expose and debug more NBD constants

The NBD protocol has several constants defined in various extensions
that we are about to implement.  Expose them to the code, along with
an easy way to map various constants to strings during diagnostic
messages.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170707203049.534-4-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 34 insertions, 18 deletions

diff --git a/nbd/client.c b/nbd/client.c
index 1250273..a443e51 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -1,5 +1,5 @@
 /*
- *  Copyright (C) 2016 Red Hat, Inc.
+ *  Copyright (C) 2016-2017 Red Hat, Inc.
  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
  *
  *  Network Block Device Client Side
@@ -104,7 +104,7 @@ static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt,
     if (len == -1) {
         req.length = len = strlen(data);
     }
-    trace_nbd_send_option_request(opt, len);
+    trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len);
 
     stq_be_p(&req.magic, NBD_OPTS_MAGIC);
     stl_be_p(&req.option, opt);
@@ -154,7 +154,9 @@ static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
     be32_to_cpus(&reply->type);
     be32_to_cpus(&reply->length);
 
-    trace_nbd_receive_option_reply(reply->option, reply->type, reply->length);
+    trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option),
+                                   reply->type, nbd_rep_lookup(reply->type),
+                                   reply->length);
 
     if (reply->magic != NBD_REP_MAGIC) {
         error_setg(errp, "Unexpected option reply magic");
@@ -188,12 +190,16 @@ static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
 
     if (reply->length) {
         if (reply->length > NBD_MAX_BUFFER_SIZE) {
-            error_setg(errp, "server's error message is too long");
+            error_setg(errp, "server error 0x%" PRIx32
+                       " (%s) message is too long",
+                       reply->type, nbd_rep_lookup(reply->type));
             goto cleanup;
         }
         msg = g_malloc(reply->length + 1);
         if (nbd_read(ioc, msg, reply->length, errp) < 0) {
-            error_prepend(errp, "failed to read option error message");
+            error_prepend(errp, "failed to read option error 0x%" PRIx32
+                          " (%s) message",
+                          reply->type, nbd_rep_lookup(reply->type));
             goto cleanup;
         }
         msg[reply->length] = '\0';
@@ -201,38 +207,48 @@ static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply,
 
     switch (reply->type) {
     case NBD_REP_ERR_UNSUP:
-        trace_nbd_reply_err_unsup(reply->option);
+        trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
         result = 0;
         goto cleanup;
 
     case NBD_REP_ERR_POLICY:
-        error_setg(errp, "Denied by server for option %" PRIx32,
-                   reply->option);
+        error_setg(errp, "Denied by server for option %" PRIx32 " (%s)",
+                   reply->option, nbd_opt_lookup(reply->option));
         break;
 
     case NBD_REP_ERR_INVALID:
-        error_setg(errp, "Invalid data length for option %" PRIx32,
-                   reply->option);
+        error_setg(errp, "Invalid data length for option %" PRIx32 " (%s)",
+                   reply->option, nbd_opt_lookup(reply->option));
         break;
 
     case NBD_REP_ERR_PLATFORM:
-        error_setg(errp, "Server lacks support for option %" PRIx32,
-                   reply->option);
+        error_setg(errp, "Server lacks support for option %" PRIx32 " (%s)",
+                   reply->option, nbd_opt_lookup(reply->option));
         break;
 
     case NBD_REP_ERR_TLS_REQD:
-        error_setg(errp, "TLS negotiation required before option %" PRIx32,
-                   reply->option);
+        error_setg(errp, "TLS negotiation required before option %" PRIx32
+                   " (%s)", reply->option, nbd_opt_lookup(reply->option));
+        break;
+
+    case NBD_REP_ERR_UNKNOWN:
+        error_setg(errp, "Requested export not available for option %" PRIx32
+                   " (%s)", reply->option, nbd_opt_lookup(reply->option));
         break;
 
     case NBD_REP_ERR_SHUTDOWN:
-        error_setg(errp, "Server shutting down before option %" PRIx32,
-                   reply->option);
+        error_setg(errp, "Server shutting down before option %" PRIx32 " (%s)",
+                   reply->option, nbd_opt_lookup(reply->option));
+        break;
+
+    case NBD_REP_ERR_BLOCK_SIZE_REQD:
+        error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIx32
+                   " (%s)", reply->option, nbd_opt_lookup(reply->option));
         break;
 
     default:
-        error_setg(errp, "Unknown error code when asking for option %" PRIx32,
-                   reply->option);
+        error_setg(errp, "Unknown error code when asking for option %" PRIx32
+                   " (%s)", reply->option, nbd_opt_lookup(reply->option));
         break;
     }