[minion-cvs] Make drop messages follow the spec

[nickm@seul.org (Nick Mathewson)]

Update of /home/minion/cvsroot/src/minion/lib/mixminion
In directory moria.mit.edu:/tmp/cvs-serv9524/lib/mixminion

Modified Files:
	BuildMessage.py ClientMain.py 
Log Message:
Make drop messages follow the spec

Index: BuildMessage.py
===================================================================
RCS file: /home/minion/cvsroot/src/minion/lib/mixminion/BuildMessage.py,v
retrieving revision 1.34
retrieving revision 1.35
diff -u -d -r1.34 -r1.35
--- BuildMessage.py	9 Jan 2003 06:28:58 -0000	1.34
+++ BuildMessage.py	12 Jan 2003 04:25:27 -0000	1.35
@@ -20,10 +20,11 @@
            'buildReplyBlock', 'decodePayload' ]
 
 def buildForwardMessage(payload, exitType, exitInfo, path1, path2,
-                        paddingPRNG=None):
+                        paddingPRNG=None, suppressTag=0):
     """Construct a forward message.
             payload: The payload to deliver.  Must compress to under 28K-22b.
-                  If it does not, MixError is raised.
+                  If it does not, MixError is raised.  If the payload is
+                  None, 28K of random data is sent.
             exitType: The routing type for the final node. (2 bytes, >=0x100)
             exitInfo: The routing info for the final node, not including tag.
             path1: Sequence of ServerInfo objects for the first leg of the path
@@ -40,19 +41,25 @@
     if not path2:
         raise MixError("Second leg of path is empty")
 
-    LOG.debug("Encoding forward message for %s-byte payload",len(payload))
-    LOG.debug("  Using path %s/%s",
-                   [s.getNickname() for s in path1],
-                   [s.getNickname() for s in path2])
-    LOG.debug("  Delivering to %04x:%r", exitType, exitInfo)
-
     # Compress, pad, and checksum the payload.
-    payload = _encodePayload(payload, 0, paddingPRNG)
+    if payload is not None:
+        payload = _encodePayload(payload, 0, paddingPRNG)
+        LOG.debug("Encoding forward message for %s-byte payload",len(payload))
+    else:
+        payload = paddingPRNG.getBytes(PAYLOAD_LEN)
+        LOG.debug("Generating DROP message with %s bytes", PAYLOAD_LEN)
 
+    LOG.debug("  Using path %s:%s",
+                   ",".join([s.getNickname() for s in path1]),
+                   ",".join([s.getNickname() for s in path2]))
+    LOG.debug("  Delivering to %04x:%r", exitType, exitInfo)
+    
     # Choose a random decoding tag.
-    tag = _getRandomTag(paddingPRNG)
-    exitInfo = tag + exitInfo
-    return _buildMessage(payload, exitType, exitInfo, path1, path2,paddingPRNG)
+    if not suppressTag:
+        tag = _getRandomTag(paddingPRNG)
+        exitInfo = tag + exitInfo
+    return _buildMessage(payload, exitType, exitInfo, path1, path2,
+                         paddingPRNG)
 
 def buildEncryptedForwardMessage(payload, exitType, exitInfo, path1, path2,
                                  key, paddingPRNG=None, secretRNG=None):
@@ -375,7 +382,7 @@
         reply = path2
         path2 = None
     else:
-        if len(exitInfo) < TAG_LEN:
+        if len(exitInfo) < TAG_LEN and exitType != DROP_TYPE:
             raise MixError("Implausibly short exit info: %r"%exitInfo)
         if exitType < MIN_EXIT_TYPE and exitType != DROP_TYPE:
             raise MixError("Invalid exit type: %4x"%exitType)

Index: ClientMain.py
===================================================================
RCS file: /home/minion/cvsroot/src/minion/lib/mixminion/ClientMain.py,v
retrieving revision 1.41
retrieving revision 1.42
diff -u -d -r1.41 -r1.42
--- ClientMain.py	10 Jan 2003 20:12:04 -0000	1.41
+++ ClientMain.py	12 Jan 2003 04:25:27 -0000	1.42
@@ -828,13 +828,19 @@
 
             address -- the results of a parseAddress call
             payload -- the contents of the message to send
-            path1,path2 -- lists of servers."""
+            path1,path2 -- lists of servers.
+
+            DOCDOC payload == None.
+            """
 
         routingType, routingInfo, _ = address.getRouting()
         LOG.info("Generating payload...")
+        suppressTag = 0
+        if payload is None:
+            suppressTag = 1
         msg = mixminion.BuildMessage.buildForwardMessage(
             payload, routingType, routingInfo, servers1, servers2,
-            self.prng)
+            self.prng, suppressTag=suppressTag)
         return msg, servers1[0]
 
     def sendMessages(self, msgList, server):
@@ -1090,11 +1096,12 @@
 
     # XXXX Clean up this ugly control structure.
     if inFile is None and address.getRouting()[0] == DROP_TYPE:
-        payload = ""
+        payload = None
         LOG.info("Sending dummy message")
     else:
         if address.getRouting()[0] == DROP_TYPE:
-            LOG.warn("Sending a payload with a dummy message makes no sense")
+            LOG.error("Cannot send a payload with a DROP message.")
+            sys.exit(0)
 
         if inFile is None:
             inFile = "-"