Prior to this change, the unit tests' echo servers' connections would sometimes
linger beyond server termination. A timeout mechanism is now implemented, which
will terminate a connection and clean up its resources when the timeout is
reached. For the purpose of unit testing, test echo servers now assert that
all connections have been terminated when the servers are closed.
For threaded echo servers, the timeout mechanism involves the use of sockets
with timeouts instead of blocking sockets. This required an implementation with
the proper handling of timeout sockets at the sslconnection level.
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.
This initial commit for the PyDTLS package includes the following functionality:
* DTLS cookie exchange, using secure hmac cookies
* A platform-independent routing UDP demultiplexer
* SSL handshaking over UDP using the DTLS protocol
* Datagram exchange using the DTLS protocol
* SSL shutdown over UDP
The package is structured as follows:
* dtls: top-level package
* dtls.demux: demultiplexer package; automatically loads a
demultiplexer appropriate for the currently executing
platform
* dtls.demux.router: a routing demux for platforms whose network stacks
cannot assign incoming UDP packets to sockets based
on the sockets' connection information
* dtls.demux.osnet: a demux that uses the operating system's UDP packet
routing functionality
* dtls.err: package-wide error handling and error definitions
* dtls.sslconnection: a client and server-side connection class for
UDP network connections secured with the DTLS protocol
* dtls.openssl: a ctypes-based wrapper for the OpenSSL library
* dtls.test: test scripts, utilities, and unit tests
The following binaries are provided:
* libeay32.dll: cryptographic portion of the OpenSSL library
* ssleay32.dll: protocol portion of the OpenSSL library (depends on former)
* cygcrypto-1.0.0.dll: as libeay32.dll, but with debugging symbols
* cygssl-1.0.0.dll: as ssleay32.dll, but with debugging symbols
All binaries have been built with the MinGW tool chain, targeted for msvcr90.
The unstripped dll's can be debugged on Windows with gdb. Cygwin is not used.
Ray Brown