Reduce spammy test logging

This commit reduces spammy logging by the test framework. It truncates
logging send/receive message in mininode to 500 characters.  mininode
was previously logging the entire message sent received, which can be up
to 1MB for a full block.

test/functional/test_framework/mininode.py

@@ -1749,7 +1749,7 @@ class NodeConn(asyncore.dispatcher):
     def send_message(self, message, pushbuf=False):
         if self.state != "connected" and not pushbuf:
             raise IOError('Not connected, no pushbuf')
-        logger.debug("Send message to %s:%d: %s" % (self.dstaddr, self.dstport, repr(message)))
+        self._log_message("send", message)
         command = message.command
         data = message.serialize()
         tmsg = self.MAGIC_BYTES[self.network]
@@ -1771,9 +1771,19 @@ class NodeConn(asyncore.dispatcher):
                 self.messagemap[b'ping'] = msg_ping_prebip31
         if self.last_sent + 30 * 60 < time.time():
             self.send_message(self.messagemap[b'ping']())
-        logger.debug("Received message from %s:%d: %s" % (self.dstaddr, self.dstport, repr(message)))
+        self._log_message("receive", message)
         self.cb.deliver(self, message)
 
+    def _log_message(self, direction, msg):
+        if direction == "send":
+            log_message = "Send message to "
+        elif direction == "receive":
+            log_message = "Received message from "
+        log_message += "%s:%d: %s" % (self.dstaddr, self.dstport, repr(msg)[:500])
+        if len(log_message) > 500:
+            log_message += "... (msg truncated)"
+        logger.debug(log_message)
+
     def disconnect_node(self):
         self.disconnect = True