cmdmon: extend initialization checks

Move the message size checks to a separate function and check also
header size in the command request and reply to catch incompatible
changes.

diff --git a/cmdmon.c b/cmdmon.c
index ade1334c4b6a5f702d08152122a8258cc4fb8cc2..aafa2922fb9818b06f42d290f6660ad426883837 100644 (file)
--- a/cmdmon.c
+++ b/cmdmon.c
@@ -248,45 +248,51 @@ prepare_socket(int family, int port_number)
 
 /* ================================================== */
 
-void
-CAM_Initialise(int family)
+static void
+do_size_checks(void)
 {
-  int i, port_number;
-
-  assert(!initialised);
-  initialised = 1;
+  int i, request_length, padding_length, reply_length;
+  CMD_Request request;
+  CMD_Reply reply;
 
-  assert(sizeof (permissions) / sizeof (permissions[0]) == N_REQUEST_TYPES);
+  assert(offsetof(CMD_Request, data) == 20);
+  assert(offsetof(CMD_Reply, data) == 28);
 
   for (i = 0; i < N_REQUEST_TYPES; i++) {
-    CMD_Request r;
-    int command_length, padding_length;
-
-    r.version = PROTO_VERSION_NUMBER;
-    r.command = htons(i);
-    command_length = PKL_CommandLength(&r);
-    padding_length = PKL_CommandPaddingLength(&r);
-    if (padding_length > MAX_PADDING_LENGTH || padding_length > command_length ||
-        command_length > sizeof (CMD_Request) ||
-        (command_length && command_length < offsetof(CMD_Request, data)))
+    request.version = PROTO_VERSION_NUMBER;
+    request.command = htons(i);
+    request_length = PKL_CommandLength(&request);
+    padding_length = PKL_CommandPaddingLength(&request);
+    if (padding_length > MAX_PADDING_LENGTH || padding_length > request_length ||
+        request_length > sizeof (CMD_Request) ||
+        (request_length && request_length < offsetof(CMD_Request, data)))
       assert(0);
   }
 
   for (i = 1; i < N_REPLY_TYPES; i++) {
-    CMD_Reply r;
-    int reply_length;
-
-    r.reply = htons(i);
-    r.status = STT_SUCCESS;
-    r.data.manual_list.n_samples = htonl(MAX_MANUAL_LIST_SAMPLES);
-    reply_length = PKL_ReplyLength(&r);
+    reply.reply = htons(i);
+    reply.status = STT_SUCCESS;
+    reply.data.manual_list.n_samples = htonl(MAX_MANUAL_LIST_SAMPLES);
+    reply_length = PKL_ReplyLength(&reply);
     if ((reply_length && reply_length < offsetof(CMD_Reply, data)) ||
         reply_length > sizeof (CMD_Reply))
       assert(0);
   }
+}
 
-  sock_fdu = -1;
+/* ================================================== */
+
+void
+CAM_Initialise(int family)
+{
+  int port_number;
 
+  assert(!initialised);
+  assert(sizeof (permissions) / sizeof (permissions[0]) == N_REQUEST_TYPES);
+  do_size_checks();
+
+  initialised = 1;
+  sock_fdu = -1;
   port_number = CNF_GetCommandPort();
 
   if (port_number && (family == IPADDR_UNSPEC || family == IPADDR_INET4))