Add sync support

But still not working. Frames read from pppd via pty sometime are
broken, I don't know why.

sstpd/__main__.py

@@ -28,6 +28,7 @@ def _getArgs():
             'pppd': '/usr/sbin/pppd',
             'pppd_config': '/etc/ppp/options.sstpd',
             'local': '192.168.20.1',
+            'sync': False,
             'log_level': logging.INFO
     }
     if args.conf_file:
@@ -75,6 +76,9 @@ def _getArgs():
     parser.add_argument('--ciphers',
             metavar="CIPHER-LIST",
             help='Custom OpenSSL cipher suite. See ciphers(1).')
+    parser.add_argument('--sync',
+            action='store_true',
+            help="Enable Synchronous HDLC.")
     parser.add_argument('-v', '--log-level',
             type=int, metavar='LOG-LEVEL',
             help="1 to 50. Default 20, debug 10, verbose 5.")

sstpd/ppp.py

@@ -12,23 +12,47 @@
 class PPPDProtocol(ProcessProtocol):
     implements(interfaces.IPushProducer)
 
-    def __init__(self):
+    def __init__(self, sync):
         self.frameBuffer = b''
         self.frameEscaped = False
         self.paused = False
+        self.sync = sync
 
 
     def writeFrame(self, frame):
-        self.transport.write(escape(frame))
+        if self.sync:
+            self.transport.write(frame)
+        else:
+            self.transport.write(escape(frame))
 
 
     def outReceived(self, data):
         if __debug__:
             logging.log(VERBOSE, "Raw data: %s", hexdump(data))
-        frames, self.frameBuffer, self.frameEscaped = \
-                unescape(data, self.frameBuffer, self.frameEscaped)
-        for frame in frames:
-            self.pppFrameReceived(frame)
+        if self.sync:
+            data = self.frameBuffer + data
+            self.frameBuffer = b''
+            start = 0
+            while start < len(data):
+                if data[start] == '\xff':
+                    length = ord(data[start+6]) << 8 | ord(data[start+7])
+                    length += 4
+                elif data[start] not in ('\xff', '\x80', '\x82', '\xc0', '\xc2', '\xc4'):
+                    length = ord(data[start+3]) << 8 | ord(data[start+4])
+                    length += 1  # proto no. on first byte
+                    #logging.info("length: %s", length)
+                else:
+                    length = len(data) - start
+                if start + length <= len(data):
+                    self.pppFrameReceived(data[start:start+length])
+                else:
+                    self.frameBuffer = data[start:]
+                start += length
+        else:
+            frames, self.frameBuffer, self.frameEscaped = \
+                    unescape(data, self.frameBuffer, self.frameEscaped)
+            for frame in frames:
+                self.pppFrameReceived(frame)
 
 
     def pppFrameReceived(self, frame):

sstpd/sstp.py

@@ -208,7 +208,7 @@ def sstpMsgCallConnectRequestReceived(self, protocolId):
         ack.attributes = [(SSTP_ATTRIB_CRYPTO_BINDING_REQ,
                 '\x00\x00\x00' + '\x03' + self.nonce)]
         ack.writeTo(self.transport.write)
-        self.pppd = PPPDProtocol()
+        self.pppd = PPPDProtocol(self.factory.syncMode)
         self.pppd.sstp = self
         if self.factory.remotePool:
             self.pppd.remote = self.factory.remotePool.apply()
@@ -224,6 +224,8 @@ def sstpMsgCallConnectRequestReceived(self, protocolId):
                 '115200', addressArgument]
         if self.remoteHost is not None:
             args += ['remotenumber', self.remoteHost]
+        if self.factory.syncMode:
+            args += ['sync']
         reactor.spawnProcess(self.pppd, self.factory.pppd, args=args, usePTY=True)
         self.transport.registerProducer(self.pppd, True)
         self.pppd.resumeProducing()
@@ -395,4 +397,5 @@ def __init__(self, config, remotePool, certHash=None):
         self.proxyProtocol = config.proxy_protocol
         self.remotePool = remotePool
         self.certHash = certHash
+        self.syncMode = config.sync