The new module test_perf.py can be used to characterize protocol
performance over a particular network link. Two stream protocols
(TCP and SSL) and two datagram protocols (UDP and DTLS) are available
for relative comparison.
The module will run servers in its process, and will spawn clients either
into separate processes, or, depending on command line options, will
expect one or more remote clients to connect to it. In the latter case,
jobs will be sent to such clients via a shared queue whenever the user
selects a test suite.
Stress testing under packet loss conditions revealed that that the
OpenSSL library's compression feature needed to be explicitly disabled
for DTLS: it evidently operates at the stream layer as opposed to the
datagram layer, and packet loss would result in corruption among the
packets that were successfully received, authenticated, and decrypted.
Several performance improvements are included in this patch.
The unit test suite was previously being run with IPv4 protocol addresses only.
With this change, we run the entire test suite twice: first with v4 addresses,
and then with v6 addresses, for all client and server-side sockets.
A patch implementation is provided, which augments and alters the Python
standard library's ssl module to support passing of datagram sockets, in which
case this package's DTLS protocol support will be activated. The ssl module's
interface is intended to operate identically regardless of whether the DTLS
protocol or another protocol is chosen.
The following features of the ssl module are explicitly supported with
datagram sockets:
* socket wrapping, unwrapping, and re-wrapping
* threaded UDP servers
* asynchronous UDP servers (asyncore integration)
* socket servers (SocketServer integration)
The following modules have been added:
* dtls.patch: standard library module patching code and substitution
functions and methods
* unit.py: this is a port of the standard library's testing module
test_ssl.py for datagram sockets; all tests pass at this time;
a couple of inapplicable tests have been dropped; a few other
tests have been added
Also note that the err module's exception raising mechanism has been
augmented so as to raise exceptions of type ssl.SSLError (as opposed to
dtls.err.SSLError) when instructed to do so through activation of the patching
mechanism. This allows code written against the standard library module's
interface to remain unchanged. In some cases, types derived from
ssl.SSLError are raised.
Ray Brown