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, 92 insertions, 0 deletions

diff --git a/nbd/common.c b/nbd/common.c
index 4dab41e2c0..a2f28f2eec 100644
--- a/nbd/common.c
+++ b/nbd/common.c
@@ -101,3 +101,95 @@ void nbd_tls_handshake(QIOTask *task,
     data->complete = true;
     g_main_loop_quit(data->loop);
 }
+
+
+const char *nbd_opt_lookup(uint32_t opt)
+{
+    switch (opt) {
+    case NBD_OPT_EXPORT_NAME:
+        return "export name";
+    case NBD_OPT_ABORT:
+        return "abort";
+    case NBD_OPT_LIST:
+        return "list";
+    case NBD_OPT_STARTTLS:
+        return "starttls";
+    case NBD_OPT_INFO:
+        return "info";
+    case NBD_OPT_GO:
+        return "go";
+    case NBD_OPT_STRUCTURED_REPLY:
+        return "structured reply";
+    default:
+        return "<unknown>";
+    }
+}
+
+
+const char *nbd_rep_lookup(uint32_t rep)
+{
+    switch (rep) {
+    case NBD_REP_ACK:
+        return "ack";
+    case NBD_REP_SERVER:
+        return "server";
+    case NBD_REP_INFO:
+        return "info";
+    case NBD_REP_ERR_UNSUP:
+        return "unsupported";
+    case NBD_REP_ERR_POLICY:
+        return "denied by policy";
+    case NBD_REP_ERR_INVALID:
+        return "invalid";
+    case NBD_REP_ERR_PLATFORM:
+        return "platform lacks support";
+    case NBD_REP_ERR_TLS_REQD:
+        return "TLS required";
+    case NBD_REP_ERR_UNKNOWN:
+        return "export unknown";
+    case NBD_REP_ERR_SHUTDOWN:
+        return "server shutting down";
+    case NBD_REP_ERR_BLOCK_SIZE_REQD:
+        return "block size required";
+    default:
+        return "<unknown>";
+    }
+}
+
+
+const char *nbd_info_lookup(uint16_t info)
+{
+    switch (info) {
+    case NBD_INFO_EXPORT:
+        return "export";
+    case NBD_INFO_NAME:
+        return "name";
+    case NBD_INFO_DESCRIPTION:
+        return "description";
+    case NBD_INFO_BLOCK_SIZE:
+        return "block size";
+    default:
+        return "<unknown>";
+    }
+}
+
+
+const char *nbd_cmd_lookup(uint16_t cmd)
+{
+    switch (cmd) {
+    case NBD_CMD_READ:
+        return "read";
+    case NBD_CMD_WRITE:
+        return "write";
+    case NBD_CMD_DISC:
+        return "discard";
+    case NBD_CMD_FLUSH:
+        return "flush";
+    case NBD_CMD_TRIM:
+        return "trim";
+    case NBD_CMD_WRITE_ZEROES:
+        return "write zeroes";
+    default:
+        return "<unknown>";
+    }
+}