[Pkg-privacy-commits] [obfsproxy] 130/353: Retrieve the shared secret in obfs2 using SOCKS arguments.

[Ximin Luo]

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infinity0 pushed a commit to branch master
in repository obfsproxy.

commit 6948f44d94450567b88cb299a857eafd58193947
Author: George Kadianakis <desnacked at riseup.net>
Date:   Tue Mar 5 01:04:17 2013 +0200

    Retrieve the shared secret in obfs2 using SOCKS arguments.
---
 ChangeLog                     |  3 +++
 obfsproxy/transports/obfs2.py | 33 +++++++++++++++++++++++++++++----
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index b4e6df2..a54b74a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,9 +1,12 @@
 Changes in version 0.0.3 - ??
  - Add support for logging exceptions to logfiles.
  - Add shared secret support to obfs2.
+ - Add support for per-connection SOCKS arguments.
+
 
 Changes in version 0.0.2 - 2013-02-17
  - Add some more files to the MANIFEST.in.
 
+
 Changes in version 0.0.1 - 2013-02-15
  - Initial release.
diff --git a/obfsproxy/transports/obfs2.py b/obfsproxy/transports/obfs2.py
index 379dbda..98ed09a 100644
--- a/obfsproxy/transports/obfs2.py
+++ b/obfsproxy/transports/obfs2.py
@@ -87,10 +87,8 @@ class Obfs2Transport(base.BaseTransport):
 
         # Crypto to encrypt outgoing data.
         self.send_crypto = None
-        # Crypto to encrypt outgoing padding. Generate it now.
-        self.send_padding_crypto = \
-            self._derive_padding_crypto(self.initiator_seed if self.we_are_initiator else self.responder_seed,
-                                        self.send_pad_keytype)
+        # Crypto to encrypt outgoing padding.
+        self.send_padding_crypto = None
         # Crypto to decrypt incoming data.
         self.recv_crypto = None
         # Crypto to decrypt incoming padding.
@@ -119,11 +117,38 @@ class Obfs2Transport(base.BaseTransport):
 
         super(Obfs2Transport, cls).validate_external_mode_cli(args)
 
+    def handle_socks_args(self, args):
+        log.debug("obfs2: Got '%s' as SOCKS arguments." % args)
+
+        # A shared secret might already be set if obfsproxy is in
+        # external-mode and both a cli shared-secret was specified
+        # _and_ a SOCKS per-connection shared secret.
+        if self.shared_secret:
+            log.notice("obfs2: Hm. Weird configuration. A shared secret "
+                       "was specified twice. I will keep the one "
+                       "supplied by the SOCKS arguments.")
+
+        if len(args) != 1:
+            err_msg = "obfs2: Too many SOCKS arguments (%d) (%s)" % (len(args), str(args))
+            log.warning(err_msg)
+            raise base.SOCKSArgsError(err_msg)
+
+        if not args[0].startswith("shared-secret="):
+            err_msg = "obfs2: SOCKS arg is not correctly formatted  (%s)" % args[0]
+            log.warning(err_msg)
+            raise base.SOCKSArgsError(err_msg)
+
+        self.shared_secret = args[0][14:]
+
     def handshake(self, circuit):
         """
         Do the obfs2 handshake:
         SEED | E_PAD_KEY( UINT32(MAGIC_VALUE) | UINT32(PADLEN) | WR(PADLEN) )
         """
+        # Generate keys for outgoing padding.
+        self.send_padding_crypto = \
+            self._derive_padding_crypto(self.initiator_seed if self.we_are_initiator else self.responder_seed,
+                                        self.send_pad_keytype)
 
         padding_length = random.randint(0, MAX_PADDING)
         seed = self.initiator_seed if self.we_are_initiator else self.responder_seed

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