1 files changed, 128 insertions, 0 deletions
diff --git a/paramiko/ber.py b/paramiko/ber.py
new file mode 100644
index 0000000..6a7823d
--- /dev/null
+++ b/paramiko/ber.py
@@ -0,0 +1,128 @@
+# Copyright (C) 2003-2005 Robey Pointer <robey@lag.net>
+#
+# This file is part of paramiko.
+#
+# Paramiko is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+
+import struct
+import util
+
+
+class BERException (Exception):
+    pass
+
+
+class BER(object):
+    """
+    Robey's tiny little attempt at a BER decoder.
+    """
+
+    def __init__(self, content=''):
+        self.content = content
+        self.idx = 0
+
+    def __str__(self):
+        return self.content
+
+    def __repr__(self):
+        return 'BER(\'' + repr(self.content) + '\')'
+
+    def decode(self):
+        return self.decode_next()
+    
+    def decode_next(self):
+        if self.idx >= len(self.content):
+            return None
+        ident = ord(self.content[self.idx])
+        self.idx += 1
+        if (ident & 31) == 31:
+            # identifier > 30
+            ident = 0
+            while self.idx < len(self.content):
+                t = ord(self.content[self.idx])
+                self.idx += 1
+                ident = (ident << 7) | (t & 0x7f)
+                if not (t & 0x80):
+                    break
+        if self.idx >= len(self.content):
+            return None
+        # now fetch length
+        size = ord(self.content[self.idx])
+        self.idx += 1
+        if size & 0x80:
+            # more complimicated...
+            # FIXME: theoretically should handle indefinite-length (0x80)
+            t = size & 0x7f
+            if self.idx + t > len(self.content):
+                return None
+            size = util.inflate_long(self.content[self.idx : self.idx + t], True)
+            self.idx += t
+        if self.idx + size > len(self.content):
+            # can't fit
+            return None
+        data = self.content[self.idx : self.idx + size]
+        self.idx += size
+        # now switch on id
+        if ident == 0x30:
+            # sequence
+            return self.decode_sequence(data)
+        elif ident == 2:
+            # int
+            return util.inflate_long(data)
+        else:
+            # 1: boolean (00 false, otherwise true)
+            raise BERException('Unknown ber encoding type %d (robey is lazy)' % ident)
+
+    def decode_sequence(data):
+        out = []
+        b = BER(data)
+        while True:
+            x = b.decode_next()
+            if x is None:
+                return out
+            out.append(x)
+    decode_sequence = staticmethod(decode_sequence)
+
+    def encode_tlv(self, ident, val):
+        # no need to support ident > 31 here
+        self.content += chr(ident)
+        if len(val) > 0x7f:
+            lenstr = util.deflate_long(len(val))
+            self.content += chr(0x80 + len(lenstr)) + lenstr
+        else:
+            self.content += chr(len(val))
+        self.content += val
+
+    def encode(self, x):
+        if type(x) is bool:
+            if x:
+                self.encode_tlv(1, '\xff')
+            else:
+                self.encode_tlv(1, '\x00')
+        elif (type(x) is int) or (type(x) is long):
+            self.encode_tlv(2, util.deflate_long(x))
+        elif type(x) is str:
+            self.encode_tlv(4, x)
+        elif (type(x) is list) or (type(x) is tuple):
+            self.encode_tlv(0x30, self.encode_sequence(x))
+        else:
+            raise BERException('Unknown type for encoding: %s' % repr(type(x)))
+
+    def encode_sequence(data):
+        b = BER()
+        for item in data:
+            b.encode(item)
+        return str(b)
+    encode_sequence = staticmethod(encode_sequence)