Add pyftpdlib for future ftp unit tests.

From http://codereview.chromium.org/16429/ by contributor ibrar.ahmed@gmail.com

TBR=pamg

Review URL: http://codereview.chromium.org/16454

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@7427 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 89 insertions, 0 deletions

diff --git a/third_party/pyftpdlib/demo/throttled_ftpd.py b/third_party/pyftpdlib/demo/throttled_ftpd.py
new file mode 100644
index 0000000..dd3395c
--- /dev/null
+++ b/third_party/pyftpdlib/demo/throttled_ftpd.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+# throttled_ftpd.py
+
+"""ftpd supporting bandwidth throttling capabilities for data transfer.
+"""
+
+import os
+import time
+import asyncore
+
+from pyftpdlib import ftpserver
+
+
+class ThrottledDTPHandler(ftpserver.DTPHandler):
+    """A DTPHandler which wraps sending and receiving in a data counter
+    and temporarily sleeps the channel so that you burst to no more than
+    x Kb/sec average.
+    """
+
+    # maximum number of bytes to transmit in a second (0 == no limit)
+    read_limit = 0
+    write_limit = 0
+
+    def __init__(self, sock_obj, cmd_channel):
+        ftpserver.DTPHandler.__init__(self, sock_obj, cmd_channel)
+        self._timenext = 0
+        self._datacount = 0
+        self._sleeping = False
+        self._throttler = None
+
+    def readable(self):
+        return not self._sleeping and ftpserver.DTPHandler.readable(self)
+
+    def writable(self):
+        return not self._sleeping and ftpserver.DTPHandler.writable(self)
+
+    def recv(self, buffer_size):
+        chunk = asyncore.dispatcher.recv(self, buffer_size)
+        if self.read_limit:
+            self.throttle_bandwidth(len(chunk), self.read_limit)
+        return chunk
+
+    def send(self, data):
+        num_sent = asyncore.dispatcher.send(self, data)
+        if self.write_limit:
+            self.throttle_bandwidth(num_sent, self.write_limit)
+        return num_sent
+
+    def throttle_bandwidth(self, len_chunk, max_speed):
+        """A method which counts data transmitted so that you burst to
+        no more than x Kb/sec average.
+        """
+        self._datacount += len_chunk
+        if self._datacount >= max_speed:
+            self._datacount = 0
+            now = time.time()
+            sleepfor = self._timenext - now
+            if sleepfor > 0:
+                # we've passed bandwidth limits
+                def unsleep():
+                    self._sleeping = False
+                self._sleeping = True
+                self._throttler = ftpserver.CallLater(sleepfor * 2, unsleep)
+            self._timenext = now + 1
+
+    def close(self):
+        if self._throttler is not None and not self._throttler.cancelled:
+            self._throttler.cancel()
+        ftpserver.DTPHandler.close(self)
+
+
+if __name__ == '__main__':
+    authorizer = ftpserver.DummyAuthorizer()
+    authorizer.add_user('user', '12345', os.getcwd(), perm='elradfmw')
+    authorizer.add_anonymous(os.getcwd())
+
+    # use the modified DTPHandler class and set a speed limit for both
+    # sending and receiving
+    dtp_handler = ThrottledDTPHandler
+    dtp_handler.read_limit = 30072  # 30 Kb/sec (30 * 1024)
+    dtp_handler.write_limit = 30072  # 30 Kb/sec (30 * 1024)
+
+    ftp_handler = ftpserver.FTPHandler
+    ftp_handler.authorizer = authorizer
+    # have the ftp handler use the different dtp handler
+    ftp_handler.dtp_handler = dtp_handler
+
+    ftpd = ftpserver.FTPServer(('', 21), ftp_handler)
+    ftpd.serve_forever()