[Pkg-privacy-commits] [obfsproxy] 108/353: Fix the max padding error condition in obfs3.

[Ximin Luo]

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infinity0 pushed a commit to branch master
in repository obfsproxy.

commit 31f108c66321e60a5fd80b9509c3bebe16ddafa9
Author: George Kadianakis <desnacked at riseup.net>
Date:   Wed Jan 30 13:35:15 2013 +0200

    Fix the max padding error condition in obfs3.
    
    The max padding check in obfs3 did not take into account the situation
    where we receive MAX_PADDING bytes of padding plus a partial but legit
    magic string, in our TCP stream.
---
 obfsproxy/transports/obfs2.py | 1 -
 obfsproxy/transports/obfs3.py | 4 ++--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/obfsproxy/transports/obfs2.py b/obfsproxy/transports/obfs2.py
index 4e61886..ee06998 100644
--- a/obfsproxy/transports/obfs2.py
+++ b/obfsproxy/transports/obfs2.py
@@ -27,7 +27,6 @@ HASH_ITERATIONS = 100000
 
 KEYLEN = 16  # is the length of the key used by E(K,s) -- that is, 16.
 IVLEN = 16  # is the length of the IV used by E(K,s) -- that is, 16.
-HASHLEN = 16  # is the length of the output of H() -- that is, 32.
 
 ST_WAIT_FOR_KEY = 0
 ST_WAIT_FOR_PADDING = 1
diff --git a/obfsproxy/transports/obfs3.py b/obfsproxy/transports/obfs3.py
index 88390e9..0727cc2 100644
--- a/obfsproxy/transports/obfs3.py
+++ b/obfsproxy/transports/obfs3.py
@@ -20,7 +20,7 @@ MAX_PADDING = 8194
 
 PUBKEY_LEN = 192
 KEYLEN = 16  # is the length of the key used by E(K,s) -- that is, 16.
-IVLEN = 16  # is the length of the IV used by E(K,s) -- that is, 16.
+HASHLEN = 32 # length of output of sha256
 
 ST_WAIT_FOR_KEY = 0 # Waiting for public key from the other party
 ST_SEARCHING_MAGIC = 1 # Waiting for magic strings from the other party
@@ -170,7 +170,7 @@ class Obfs3Transport(base.BaseTransport):
 
         index = chunk.find(self.other_magic_value)
         if index < 0:
-            if (len(data) > MAX_PADDING):
+            if (len(data) > MAX_PADDING+HASHLEN):
                 raise base.PluggableTransportError("obfs3: Too much padding (%d)!" % len(data))
             log.debug("%s: Did not find magic this time (%d)." % (log_prefix, len(data)))
             return

-- 
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