Convert and detect types properly, use helper constants, use StringIO and range

25 files changed, 154 insertions, 145 deletions

diff --git a/paramiko/ber.py b/paramiko/ber.py
index 45372fc4..f4d2acc3 100644
--- a/paramiko/ber.py
+++ b/paramiko/ber.py
@@ -49,13 +49,13 @@ class BER(object):
     def decode_next(self):
         if self.idx >= len(self.content):
             return None
-        ident = ord(self.content[self.idx])
+        ident = byte_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])
+                t = byte_ord(self.content[self.idx])
                 self.idx += 1
                 ident = (ident << 7) | (t & 0x7f)
                 if not (t & 0x80):
@@ -63,7 +63,7 @@ class BER(object):
         if self.idx >= len(self.content):
             return None
         # now fetch length
-        size = ord(self.content[self.idx])
+        size = byte_ord(self.content[self.idx])
         self.idx += 1
         if size & 0x80:
             # more complimicated...
@@ -102,12 +102,12 @@ class BER(object):
 
     def encode_tlv(self, ident, val):
         # no need to support ident > 31 here
-        self.content += chr(ident)
+        self.content += byte_chr(ident)
         if len(val) > 0x7f:
             lenstr = util.deflate_long(len(val))
-            self.content += chr(0x80 + len(lenstr)) + lenstr
+            self.content += byte_chr(0x80 + len(lenstr)) + lenstr
         else:
-            self.content += chr(len(val))
+            self.content += byte_chr(len(val))
         self.content += val
 
     def encode(self, x):
diff --git a/paramiko/channel.py b/paramiko/channel.py
index 422986dd..d686c6d6 100644
--- a/paramiko/channel.py
+++ b/paramiko/channel.py
@@ -969,7 +969,7 @@ class Channel (object):
                 self.transport._send_user_message(m)
 
     def _feed(self, m):
-        if type(m) is str:
+        if isinstance(m, bytes_type):
             # passed from _feed_extended
             s = m
         else:
diff --git a/paramiko/client.py b/paramiko/client.py
index 98bb47f2..3881f8d4 100644
--- a/paramiko/client.py
+++ b/paramiko/client.py
@@ -335,7 +335,7 @@ class SSHClient (object):
 
         if key_filename is None:
             key_filenames = []
-        elif isinstance(key_filename, (str, unicode)):
+        elif isinstance(key_filename, string_types):
             key_filenames = [ key_filename ]
         else:
             key_filenames = key_filename
@@ -383,7 +383,7 @@ class SSHClient (object):
         return stdin, stdout, stderr
 
     def invoke_shell(self, term='vt100', width=80, height=24, width_pixels=0,
-                height_pixels=0):
+                     height_pixels=0):
         """
         Start an interactive shell session on the SSH server.  A new L{Channel}
         is opened and connected to a pseudo-terminal using the requested
diff --git a/paramiko/kex_gex.py b/paramiko/kex_gex.py
index d2ef15ca..02494539 100644
--- a/paramiko/kex_gex.py
+++ b/paramiko/kex_gex.py
@@ -91,20 +91,20 @@ class KexGex (object):
 
     ###  internals...
 
-    
+
     def _generate_x(self):
         # generate an "x" (1 < x < (p-1)/2).
         q = (self.p - 1) // 2
         qnorm = util.deflate_long(q, 0)
-        qhbyte = ord(qnorm[0])
+        qhbyte = byte_ord(qnorm[0])
         byte_count = len(qnorm)
         qmask = 0xff
         while not (qhbyte & 0x80):
             qhbyte <<= 1
             qmask >>= 1
         while True:
-            x_bytes = chr(ord(x_bytes[0]) & qmask) + x_bytes[1:]
             x_bytes = self.transport.rng.read(byte_count)
+            x_bytes = byte_mask(x_bytes[0], qmask) + x_bytes[1:]
             x = util.inflate_long(x_bytes, 1)
             if (x > 1) and (x < q):
                 break
diff --git a/paramiko/kex_group1.py b/paramiko/kex_group1.py
index 83fb87de..ea452b34 100644
--- a/paramiko/kex_group1.py
+++ b/paramiko/kex_group1.py
@@ -30,9 +30,10 @@ from paramiko.ssh_exception import SSHException
 
 
 _MSG_KEXDH_INIT, _MSG_KEXDH_REPLY = range(30, 32)
+c_MSG_KEXDH_INIT, c_MSG_KEXDH_REPLY = [byte_chr(c) for c in range(30, 32)]
 
 # draft-ietf-secsh-transport-09.txt, page 17
-P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFFL
+P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF
 G = 2
 
 
@@ -42,9 +43,9 @@ class KexGroup1(object):
 
     def __init__(self, transport):
         self.transport = transport
-        self.x = 0L
-        self.e = 0L
-        self.f = 0L
+        self.x = long_zero
+        self.e = long_zero
+        self.f = long_zero
 
     def start_kex(self):
         self._generate_x()
@@ -80,7 +81,7 @@ class KexGroup1(object):
         # larger than q (but this is a tiny tiny subset of potential x).
         while 1:
             x_bytes = self.transport.rng.read(128)
-            x_bytes = chr(ord(x_bytes[0]) & 0x7f) + x_bytes[1:]
+            x_bytes = byte_mask(x_bytes[0], 0x7f) + x_bytes[1:]
             if (x_bytes[:8] != '\x7F\xFF\xFF\xFF\xFF\xFF\xFF\xFF') and \
                    (x_bytes[:8] != '\x00\x00\x00\x00\x00\x00\x00\x00'):
                 break
diff --git a/paramiko/packet.py b/paramiko/packet.py
index 3a26b6bc..193acf69 100644
--- a/paramiko/packet.py
+++ b/paramiko/packet.py
@@ -38,6 +38,7 @@ try:
 except ImportError:
     from Crypto.Hash.HMAC import HMAC
 
+
 def compute_hmac(key, message, digest_class):
     return HMAC(key, message, digest_class).digest()
 
@@ -66,7 +67,7 @@ class Packetizer (object):
         self.__dump_packets = False
         self.__need_rekey = False
         self.__init_count = 0
-        self.__remainder = ''
+        self.__remainder = bytes()
 
         # used for noticing when to re-key:
         self.__sent_bytes = 0
@@ -90,8 +91,8 @@ class Packetizer (object):
         self.__mac_key_in = ''
         self.__compress_engine_out = None
         self.__compress_engine_in = None
-        self.__sequence_number_out = 0L
-        self.__sequence_number_in = 0L
+        self.__sequence_number_out = long_zero
+        self.__sequence_number_in = long_zero
 
         # lock around outbound writes (packet computation)
         self.__write_lock = threading.RLock()
@@ -196,7 +197,7 @@ class Packetizer (object):
         @raise EOFError: if the socket was closed before all the bytes could
             be read
         """
-        out = ''
+        out = bytes()
         # handle over-reading from reading the banner line
         if len(self.__remainder) > 0:
             out = self.__remainder[:n]
@@ -275,22 +276,22 @@ class Packetizer (object):
         line, so it's okay to attempt large reads.
         """
         buf = self.__remainder
-        while not '\n' in buf:
+        while not newline_byte in buf:
             buf += self._read_timeout(timeout)
-        n = buf.index('\n')
+        n = buf.index(newline_byte)
         self.__remainder = buf[n+1:]
         buf = buf[:n]
-        if (len(buf) > 0) and (buf[-1] == '\r'):
+        if (len(buf) > 0) and (buf[-1] == cr_byte):
             buf = buf[:-1]
-        return buf
+        return u(buf)
 
     def send_message(self, data):
         """
         Write a block of data using the current cipher, as an SSH block.
         """
         # encrypt this sucka
-        data = str(data)
-        cmd = ord(data[0])
+        data = asbytes(data)
+        cmd = byte_ord(data[0])
         if cmd in MSG_NAMES:
             cmd_name = MSG_NAMES[cmd]
         else:
@@ -312,7 +313,7 @@ class Packetizer (object):
             if self.__block_engine_out != None:
                 payload = struct.pack('>I', self.__sequence_number_out) + packet
                 out += compute_hmac(self.__mac_key_out, payload, self.__mac_engine_out)[:self.__mac_size_out]
-            self.__sequence_number_out = (self.__sequence_number_out + 1) & 0xffffffffL
+            self.__sequence_number_out = (self.__sequence_number_out + 1) & xffffffff
             self.write_all(out)
 
             self.__sent_bytes += len(out)
@@ -361,7 +362,7 @@ class Packetizer (object):
             my_mac = compute_hmac(self.__mac_key_in, mac_payload, self.__mac_engine_in)[:self.__mac_size_in]
             if my_mac != mac:
                 raise SSHException('Mismatched MAC')
-        padding = ord(packet[0])
+        padding = byte_ord(packet[0])
         payload = packet[1:packet_size - padding]
         
         if self.__dump_packets:
@@ -372,7 +373,7 @@ class Packetizer (object):
 
         msg = Message(payload[1:])
         msg.seqno = self.__sequence_number_in
-        self.__sequence_number_in = (self.__sequence_number_in + 1) & 0xffffffffL
+        self.__sequence_number_in = (self.__sequence_number_in + 1) & xffffffff
 
         # check for rekey
         raw_packet_size = packet_size + self.__mac_size_in + 4
@@ -395,7 +396,7 @@ class Packetizer (object):
             self.__received_packets_overflow = 0
             self._trigger_rekey()
 
-        cmd = ord(payload[0])
+        cmd = byte_ord(payload[0])
         if cmd in MSG_NAMES:
             cmd_name = MSG_NAMES[cmd]
         else:
@@ -493,7 +494,7 @@ class Packetizer (object):
         if self.__sdctr_out or self.__block_engine_out is None:
             # cute trick i caught openssh doing: if we're not encrypting or SDCTR mode (RFC4344),
             # don't waste random bytes for the padding
-            packet += (chr(0) * padding)
+            packet += (zero_byte * padding)
         else:
             packet += rng.read(padding)
         return packet
diff --git a/paramiko/pipe.py b/paramiko/pipe.py
index e64547bd..4c965465 100644
--- a/paramiko/pipe.py
+++ b/paramiko/pipe.py
@@ -64,7 +64,7 @@ class PosixPipe (object):
         if self._set or self._closed:
             return
         self._set = True
-        os.write(self._wfd, '*')
+        os.write(self._wfd, b('*'))
     
     def set_forever (self):
         self._forever = True
@@ -110,7 +110,7 @@ class WindowsPipe (object):
         if self._set or self._closed:
             return
         self._set = True
-        self._wsock.send('*')
+        self._wsock.send(b('*'))
 
     def set_forever (self):
         self._forever = True
diff --git a/paramiko/pkey.py b/paramiko/pkey.py
index 9c59dad4..c88e5c85 100644
--- a/paramiko/pkey.py
+++ b/paramiko/pkey.py
@@ -352,9 +352,9 @@ class PKey (object):
 
         @raise IOError: if there was an error writing the file.
         """
-        f = open(filename, 'w', 0600)
+        f = open(filename, 'w', o600)
         # grrr... the mode doesn't always take hold
-        os.chmod(filename, 0600)
+        os.chmod(filename, o600)
         self._write_private_key(tag, f, data, password)
         f.close()
 
diff --git a/paramiko/primes.py b/paramiko/primes.py
index 1dd87daf..144454aa 100644
--- a/paramiko/primes.py
+++ b/paramiko/primes.py
@@ -34,7 +34,7 @@ def _generate_prime(bits, rng):
         # loop catches the case where we increment n into a higher bit-range
         x = rng.read((bits+7) // 8)
         if hbyte_mask > 0:
-            x = chr(ord(x[0]) & hbyte_mask) + x[1:]
+            x = byte_mask(x[0], hbyte_mask) + x[1:]
         n = util.inflate_long(x, 1)
         n |= 1
         n |= (1 << (bits - 1))
@@ -59,7 +59,7 @@ def _roll_random(rng, n):
     while True:
         x = rng.read(byte_count)
         if hbyte_mask > 0:
-            x = chr(ord(x[0]) & hbyte_mask) + x[1:]
+            x = byte_mask(x[0], hbyte_mask) + x[1:]
         num = util.inflate_long(x, 1)
         if num < n:
             break
diff --git a/paramiko/server.py b/paramiko/server.py
index 4b6e8b18..f3383add 100644
--- a/paramiko/server.py
+++ b/paramiko/server.py
@@ -48,7 +48,7 @@ class InteractiveQuery (object):
         self.instructions = instructions
         self.prompts = []
         for x in prompts:
-            if (type(x) is str) or (type(x) is unicode):
+            if isinstance(x, string_types):
                 self.add_prompt(x)
             else:
                 self.add_prompt(x[0], x[1])
diff --git a/paramiko/sftp.py b/paramiko/sftp.py
index 0d1287a5..11aa3cb4 100644
--- a/paramiko/sftp.py
+++ b/paramiko/sftp.py
@@ -166,8 +166,8 @@ class BaseSFTP (object):
 
     def _send_packet(self, t, packet):
         #self._log(DEBUG2, 'write: %s (len=%d)' % (CMD_NAMES.get(t, '0x%02x' % t), len(packet)))
-        out = struct.pack('>I', len(packet) + 1) + chr(t) + packet
         packet = asbytes(packet)
+        out = struct.pack('>I', len(packet) + 1) + byte_chr(t) + packet
         if self.ultra_debug:
             self._log(DEBUG, util.format_binary(out, 'OUT: '))
         self._write_all(out)
@@ -183,7 +183,7 @@ class BaseSFTP (object):
         if self.ultra_debug:
             self._log(DEBUG, util.format_binary(data, 'IN: '));
         if size > 0:
-            t = ord(data[0])
+            t = byte_ord(data[0])
             #self._log(DEBUG2, 'read: %s (len=%d)' % (CMD_NAMES.get(t), '0x%02x' % t, len(data)-1))
             return t, data[1:]
         return 0, ''
diff --git a/paramiko/sftp_attr.py b/paramiko/sftp_attr.py
index 84c83929..5a40f4c5 100644
--- a/paramiko/sftp_attr.py
+++ b/paramiko/sftp_attr.py
@@ -44,7 +44,7 @@ class SFTPAttributes (object):
     FLAG_UIDGID = 2
     FLAG_PERMISSIONS = 4
     FLAG_AMTIME = 8
-    FLAG_EXTENDED = 0x80000000L
+    FLAG_EXTENDED = x80000000
 
     def __init__(self):
         """
@@ -194,13 +194,13 @@ class SFTPAttributes (object):
                 ks = 's'
             else:
                 ks = '?'
-            ks += self._rwx((self.st_mode & 0700) >> 6, self.st_mode & stat.S_ISUID)
-            ks += self._rwx((self.st_mode & 070) >> 3, self.st_mode & stat.S_ISGID)
+            ks += self._rwx((self.st_mode & o700) >> 6, self.st_mode & stat.S_ISUID)
+            ks += self._rwx((self.st_mode & o70) >> 3, self.st_mode & stat.S_ISGID)
             ks += self._rwx(self.st_mode & 7, self.st_mode & stat.S_ISVTX, True)
         else:
             ks = '?---------'
         # compute display date
-        if (self.st_mtime is None) or (self.st_mtime == 0xffffffffL):
+        if (self.st_mtime is None) or (self.st_mtime == xffffffff):
             # shouldn't really happen
             datestr = '(unknown date)'
         else:
diff --git a/paramiko/sftp_client.py b/paramiko/sftp_client.py
index 0e3d6c81..7703246a 100644
--- a/paramiko/sftp_client.py
+++ b/paramiko/sftp_client.py
@@ -285,7 +285,7 @@ class SFTPClient (BaseSFTP):
         self._log(DEBUG, 'rename(%r, %r)' % (oldpath, newpath))
         self._request(CMD_RENAME, oldpath, newpath)
 
-    def mkdir(self, path, mode=0777):
+    def mkdir(self, path, mode=o777):
         """
         Create a folder (directory) named C{path} with numeric mode C{mode}.
         The default mode is 0777 (octal).  On some systems, mode is ignored.
@@ -698,7 +698,7 @@ class SFTPClient (BaseSFTP):
                     msg.add_int(item)
                 elif isinstance(item, long):
                     msg.add_int64(item)
-                elif isinstance(item, str):
+                elif isinstance(item, string_types):
                     msg.add_string(item)
                 elif isinstance(item, SFTPAttributes):
                     item._pack(msg)
diff --git a/paramiko/sftp_server.py b/paramiko/sftp_server.py
index 96c1f04b..63fe5cc6 100644
--- a/paramiko/sftp_server.py
+++ b/paramiko/sftp_server.py
@@ -183,7 +183,7 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
                 msg.add_int(item)
             elif type(item) is long:
                 msg.add_int64(item)
-            elif type(item) is str:
+            elif isinstance(item, string_types):
                 msg.add_string(item)
             elif type(item) is SFTPAttributes:
                 item._pack(msg)
@@ -420,7 +420,7 @@ class SFTPServer (BaseSFTP, SubsystemHandler):
         elif t == CMD_READLINK:
             path = msg.get_text()
             resp = self.server.readlink(path)
-            if type(resp) is str:
+            if isinstance(resp, string_types):
                 self._response(request_number, CMD_NAME, 1, resp, '', SFTPAttributes())
             else:
                 self._send_status(request_number, resp)
diff --git a/paramiko/transport.py b/paramiko/transport.py
index c9e81fa7..101fe174 100644
--- a/paramiko/transport.py
+++ b/paramiko/transport.py
@@ -376,7 +376,7 @@ class Transport (threading.Thread):
 
         @rtype: str
         """
-        out = '<paramiko.Transport at %s' % hex(long(id(self)) & 0xffffffffL)
+        out = '<paramiko.Transport at %s' % hex(long(id(self)) & xffffffff)
         if not self.active:
             out += ' (unconnected)'
         else:
@@ -1553,12 +1553,12 @@ class Transport (threading.Thread):
         # active=True occurs before the thread is launched, to avoid a race
         _active_threads.append(self)
         if self.server_mode:
-            self._log(DEBUG, 'starting thread (server mode): %s' % hex(long(id(self)) & 0xffffffffL))
+            self._log(DEBUG, 'starting thread (server mode): %s' % hex(long(id(self)) & xffffffff))
         else:
-            self._log(DEBUG, 'starting thread (client mode): %s' % hex(long(id(self)) & 0xffffffffL))
+            self._log(DEBUG, 'starting thread (client mode): %s' % hex(long(id(self)) & xffffffff))
         try:
             try:
-                self.packetizer.write_all(self.local_version + '\r\n')
+                self.packetizer.write_all(b(self.local_version + '\r\n'))
                 self._check_banner()
                 self._send_kex_init()
                 self._expect_packet(MSG_KEXINIT)
diff --git a/paramiko/util.py b/paramiko/util.py
index 299f44a6..61fdcc6a 100644
--- a/paramiko/util.py
+++ b/paramiko/util.py
@@ -48,60 +48,53 @@ if sys.version_info < (2,3):
 
 def inflate_long(s, always_positive=False):
     "turns a normalized byte string into a long-int (adapted from Crypto.Util.number)"
-    out = 0L
+    out = long_zero
     negative = 0
-    if not always_positive and (len(s) > 0) and (ord(s[0]) >= 0x80):
+    if not always_positive and (len(s) > 0) and (byte_ord(s[0]) >= 0x80):
         negative = 1
     if len(s) % 4:
-        filler = '\x00'
+        filler = zero_byte
         if negative:
-            filler = '\xff'
+            filler = max_byte
         s = filler * (4 - len(s) % 4) + s
     for i in range(0, len(s), 4):
         out = (out << 32) + struct.unpack('>I', s[i:i+4])[0]
     if negative:
-        out -= (1L << (8 * len(s)))
+        out -= (long_one << (8 * len(s)))
     return out
 
+deflate_zero = 0 if PY3 else zero_byte
+deflate_ff = 0xff if PY3 else max_byte
+
 def deflate_long(n, add_sign_padding=True):
     "turns a long-int into a normalized byte string (adapted from Crypto.Util.number)"
     # after much testing, this algorithm was deemed to be the fastest
-    s = ''
+    s = bytes()
     n = long(n)
     while (n != 0) and (n != -1):
-        s = struct.pack('>I', n & 0xffffffffL) + s
+        s = struct.pack('>I', n & xffffffff) + s
         n = n >> 32
     # strip off leading zeros, FFs
     for i in enumerate(s):
-        if (n == 0) and (i[1] != '\000'):
+        if (n == 0) and (i[1] != deflate_zero):
             break
-        if (n == -1) and (i[1] != '\xff'):
+        if (n == -1) and (i[1] != deflate_ff):
             break
     else:
         # degenerate case, n was either 0 or -1
         i = (0,)
         if n == 0:
-            s = '\000'
+            s = zero_byte
         else:
-            s = '\xff'
+            s = max_byte
     s = s[i[0]:]
     if add_sign_padding:
-        if (n == 0) and (ord(s[0]) >= 0x80):
-            s = '\x00' + s
-        if (n == -1) and (ord(s[0]) < 0x80):
-            s = '\xff' + s
+        if (n == 0) and (byte_ord(s[0]) >= 0x80):
+            s = zero_byte + s
+        if (n == -1) and (byte_ord(s[0]) < 0x80):
+            s = max_byte + s
     return s
 
-def format_binary_weird(data):
-    out = ''
-    for i in enumerate(data):
-        out += '%02X' % ord(i[1])
-        if i[0] % 2:
-            out += ' '
-        if i[0] % 16 == 15:
-            out += '\n'
-    return out
-
 def format_binary(data, prefix=''):
     x = 0
     out = []
@@ -113,8 +106,8 @@ def format_binary(data, prefix=''):
     return [prefix + x for x in out]
 
 def format_binary_line(data):
-    left = ' '.join(['%02X' % ord(c) for c in data])
-    right = ''.join([('.%c..' % c)[(ord(c)+63)//95] for c in data])
+    left = ' '.join(['%02X' % byte_ord(c) for c in data])
+    right = ''.join([('.%c..' % c)[(byte_ord(c)+63)//95] for c in data])
     return '%-50s %s' % (left, right)
 
 def hexify(s):
@@ -126,17 +119,17 @@ def unhexify(s):
 def safe_string(s):
     out = ''
     for c in s:
-        if (ord(c) >= 32) and (ord(c) <= 127):
+        if (byte_ord(c) >= 32) and (byte_ord(c) <= 127):
             out += c
         else:
-            out += '%%%02X' % ord(c)
+            out += '%%%02X' % byte_ord(c)
     return out
 
 # ''.join([['%%%02X' % ord(c), c][(ord(c) >= 32) and (ord(c) <= 127)] for c in s])
 
 def bit_length(n):
     norm = deflate_long(n, 0)
-    hbyte = ord(norm[0])
+    hbyte = byte_ord(norm[0])
     if hbyte == 0:
         return 1
     bitlen = len(norm) * 8
@@ -298,15 +291,15 @@ class Counter (object):
         """Increament the counter and return the new value"""
         i = self.blocksize - 1
         while i > -1:
-            c = self.value[i] = chr((ord(self.value[i]) + 1) % 256)
-            if c != '\x00':
+            c = self.value[i] = byte_chr((byte_ord(self.value[i]) + 1) % 256)
+            if c != zero_byte:
                 return self.value.tostring()
             i -= 1
         # counter reset
         x = deflate_long(self.overflow, add_sign_padding=False)
-        self.value = array.array('c', '\x00' * (self.blocksize - len(x)) + x)
+        self.value = array.array('c', zero_byte * (self.blocksize - len(x)) + x)
         return self.value.tostring()
 
-    def new(cls, nbits, initial_value=1L, overflow=0L):
+    def new(cls, nbits, initial_value=long_one, overflow=long_zero):
         return cls(nbits, initial_value=initial_value, overflow=overflow)
     new = classmethod(new)
diff --git a/tests/loop.py b/tests/loop.py
index 2f3f5dfc..cfd76265 100644
--- a/tests/loop.py
+++ b/tests/loop.py
@@ -32,7 +32,7 @@ class LoopSocket (object):
     """
     
     def __init__(self):
-        self.__in_buffer = ''
+        self.__in_buffer = bytes()
         self.__lock = threading.Lock()
         self.__cv = threading.Condition(self.__lock)
         self.__timeout = None
@@ -42,7 +42,7 @@ class LoopSocket (object):
         self.__unlink()
         try:
             self.__lock.acquire()
-            self.__in_buffer = ''
+            self.__in_buffer = bytes()
         finally:
             self.__lock.release()
 
diff --git a/tests/stub_sftp.py b/tests/stub_sftp.py
index b8bea9b5..26ca13b3 100644
--- a/tests/stub_sftp.py
+++ b/tests/stub_sftp.py
@@ -104,7 +104,7 @@ class StubSFTPServer (SFTPServerInterface):
             else:
                 # os.open() defaults to 0777 which is
                 # an odd default mode for files
-                fd = os.open(path, flags, 0666)
+                fd = os.open(path, flags, o666)
         except OSError:
             e = sys.exc_info()[1]
             return SFTPServer.convert_errno(e.errno)
diff --git a/tests/test_auth.py b/tests/test_auth.py
index a7c9e61b..5fd0bf5d 100644
--- a/tests/test_auth.py
+++ b/tests/test_auth.py
@@ -32,6 +32,11 @@ from paramiko import OPEN_SUCCEEDED, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
 from tests.loop import LoopSocket
 from tests.util import test_path
 
+try:
+    _pwd = u'\u2022'
+except Exception:
+    _pwd = '\u2022'
+
 
 class NullServer (ServerInterface):
     paranoid_did_password = False
@@ -65,7 +70,7 @@ class NullServer (ServerInterface):
             if self.paranoid_did_public_key:
                 return AUTH_SUCCESSFUL
             return AUTH_PARTIALLY_SUCCESSFUL
-        if (username == 'utf8') and (password == u'\u2022'):
+        if (username == 'utf8') and (password == _pwd):
             return AUTH_SUCCESSFUL
         if (username == 'non-utf8') and (password == '\xff'):
             return AUTH_SUCCESSFUL
@@ -203,7 +208,7 @@ class AuthTest (unittest.TestCase):
         """
         self.start_server()
         self.tc.connect(hostkey=self.public_host_key)
-        remain = self.tc.auth_password('utf8', u'\u2022')
+        remain = self.tc.auth_password('utf8', _pwd)
         self.assertEquals([], remain)
         self.verify_finished()
 
diff --git a/tests/test_kex.py b/tests/test_kex.py
index 21986fcc..c94b777b 100644
--- a/tests/test_kex.py
+++ b/tests/test_kex.py
@@ -31,7 +31,7 @@ from paramiko.common import *
 
 class FakeRng (object):
     def read(self, n):
-        return chr(0xcc) * n
+        return byte_chr(0xcc) * n
 
 
 class FakeKey (object):
@@ -44,7 +44,7 @@ class FakeKey (object):
 
 
 class FakeModulusPack (object):
-    P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFFL
+    P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF
     G = 2
     def get_modulus(self, min, ask, max):
         return self.G, self.P
@@ -78,7 +78,7 @@ class FakeTransport (object):
 
 class KexTest (unittest.TestCase):
 
-    K = 14730343317708716439807310032871972459448364195094179797249681733965528989482751523943515690110179031004049109375612685505881911274101441415545039654102474376472240501616988799699744135291070488314748284283496055223852115360852283821334858541043710301057312858051901453919067023103730011648890038847384890504L
+    K = 14730343317708716439807310032871972459448364195094179797249681733965528989482751523943515690110179031004049109375612685505881911274101441415545039654102474376472240501616988799699744135291070488314748284283496055223852115360852283821334858541043710301057312858051901453919067023103730011648890038847384890504
 
     def setUp(self):
         pass
diff --git a/tests/test_pkey.py b/tests/test_pkey.py
index 589a35d8..c7240db3 100644
--- a/tests/test_pkey.py
+++ b/tests/test_pkey.py
@@ -99,7 +99,7 @@ class KeyTest (unittest.TestCase):
         self.assertEquals(PUB_RSA.split()[1], key.get_base64())
         self.assertEquals(1024, key.get_bits())
 
-        s = StringIO.StringIO()
+        s = StringIO()
         key.write_private_key(s)
         self.assertEquals(RSA_PRIVATE_OUT, s.getvalue()) 
         s.seek(0)
@@ -124,7 +124,7 @@ class KeyTest (unittest.TestCase):
         self.assertEquals(PUB_DSS.split()[1], key.get_base64())
         self.assertEquals(1024, key.get_bits())
 
-        s = StringIO.StringIO()
+        s = StringIO()
         key.write_private_key(s)
         self.assertEquals(DSS_PRIVATE_OUT, s.getvalue())
         s.seek(0)
@@ -207,7 +207,7 @@ class KeyTest (unittest.TestCase):
         self.assertEquals(PUB_ECDSA.split()[1], key.get_base64())
         self.assertEquals(256, key.get_bits())
 
-        s = StringIO.StringIO()
+        s = StringIO()
         key.write_private_key(s)
         self.assertEquals(ECDSA_PRIVATE_OUT, s.getvalue())
         s.seek(0)
diff --git a/tests/test_sftp.py b/tests/test_sftp.py
index a4452711..c80967d1 100755
--- a/tests/test_sftp.py
+++ b/tests/test_sftp.py
@@ -71,7 +71,10 @@ FOLDER = os.environ.get('TEST_FOLDER', 'temp-testing000')
 sftp = None
 tc = None
 g_big_file_test = True
-
+try:
+    unicode_folder = u'\u00fcnic\u00f8de'
+except SyntaxError:
+    unicode_folder = '\u00fcnic\u00f8de'
 
 def get_sftp():
     global sftp
@@ -141,7 +144,7 @@ class SFTPTest (unittest.TestCase):
 
     def setUp(self):
         global FOLDER
-        for i in xrange(1000):
+        for i in range(1000):
             FOLDER = FOLDER[:-3] + '%03d' % i
             try:
                 sftp.mkdir(FOLDER)
@@ -236,7 +239,7 @@ class SFTPTest (unittest.TestCase):
                 pass
             f = sftp.open(FOLDER + '/second.txt', 'r')
             f.seek(-6, f.SEEK_END)
-            self.assertEqual(f.read(4), 'tent')
+            self.assertEqual(u(f.read(4)), 'tent')
             f.close()
         finally:
             try:
@@ -301,16 +304,16 @@ class SFTPTest (unittest.TestCase):
             f.close()
 
             stat = sftp.stat(FOLDER + '/special')
-            sftp.chmod(FOLDER + '/special', (stat.st_mode & ~0777) | 0600)
+            sftp.chmod(FOLDER + '/special', (stat.st_mode & ~o777) | o600)
             stat = sftp.stat(FOLDER + '/special')
-            expected_mode = 0600
+            expected_mode = o600
             if sys.platform == 'win32':
                 # chmod not really functional on windows
-                expected_mode = 0666
+                expected_mode = o666
             if sys.platform == 'cygwin':
                 # even worse.
-                expected_mode = 0644
-            self.assertEqual(stat.st_mode & 0777, expected_mode)
+                expected_mode = o644
+            self.assertEqual(stat.st_mode & o777, expected_mode)
             self.assertEqual(stat.st_size, 1024)
 
             mtime = stat.st_mtime - 3600
@@ -341,17 +344,17 @@ class SFTPTest (unittest.TestCase):
 
             f = sftp.open(FOLDER + '/special', 'r+')
             stat = f.stat()
-            f.chmod((stat.st_mode & ~0777) | 0600)
+            f.chmod((stat.st_mode & ~o777) | o600)
             stat = f.stat()
 
-            expected_mode = 0600
+            expected_mode = o600
             if sys.platform == 'win32':
                 # chmod not really functional on windows
-                expected_mode = 0666
+                expected_mode = o666
             if sys.platform == 'cygwin':
                 # even worse.
-                expected_mode = 0644
-            self.assertEqual(stat.st_mode & 0777, expected_mode)
+                expected_mode = o644
+            self.assertEqual(stat.st_mode & o777, expected_mode)
             self.assertEqual(stat.st_size, 1024)
 
             mtime = stat.st_mtime - 3600
@@ -643,7 +646,7 @@ class SFTPTest (unittest.TestCase):
         f.close()
 
         try:
-            sftp.rename(FOLDER + '/something', FOLDER + u'/\u00fcnic\u00f8de')
+            sftp.rename(FOLDER + '/something', FOLDER + '/' + unicode_folder)
             sftp.open(FOLDER + '/\xc3\xbcnic\xc3\xb8\x64\x65', 'r')
         except Exception:
             e = sys.exc_info()[1]
@@ -651,16 +654,16 @@ class SFTPTest (unittest.TestCase):
         sftp.unlink(FOLDER + '/\xc3\xbcnic\xc3\xb8\x64\x65')
 
     def test_L_utf8_chdir(self):
-        sftp.mkdir(FOLDER + u'\u00fcnic\u00f8de')
+        sftp.mkdir(FOLDER + '/' + unicode_folder)
         try:
-            sftp.chdir(FOLDER + u'\u00fcnic\u00f8de')
+            sftp.chdir(FOLDER + '/' + unicode_folder)
             f = sftp.open('something', 'w')
             f.write('okay')
             f.close()
             sftp.unlink('something')
         finally:
             sftp.chdir(None)
-            sftp.rmdir(FOLDER + u'\u00fcnic\u00f8de')
+            sftp.rmdir(FOLDER + '/' + unicode_folder)
 
     def test_M_bad_readv(self):
         """
@@ -733,10 +736,16 @@ class SFTPTest (unittest.TestCase):
         Send an empty file and confirm it is sent.
         """
         target = FOLDER + '/empty file.txt'
-        stream = StringIO.StringIO()
+        stream = StringIO()
         try:
             attrs = sftp.putfo(stream, target)
             # the returned attributes should not be null
             self.assertNotEqual(attrs, None)
         finally:
             sftp.remove(target)
+
+
+if __name__ == '__main__':
+    SFTPTest.init_loopback()
+    from unittest import main
+    main()
diff --git a/tests/test_sftp_big.py b/tests/test_sftp_big.py
index 94088f78..20bf0075 100644
--- a/tests/test_sftp_big.py
+++ b/tests/test_sftp_big.py
@@ -46,7 +46,7 @@ class BigSFTPTest (unittest.TestCase):
     def setUp(self):
         global FOLDER
         sftp = get_sftp()
-        for i in xrange(1000):
+        for i in range(1000):
             FOLDER = FOLDER[:-3] + '%03d' % i
             try:
                 sftp.mkdir(FOLDER)
@@ -69,7 +69,7 @@ class BigSFTPTest (unittest.TestCase):
                 f = sftp.open('%s/file%d.txt' % (FOLDER, i), 'w', 1)
                 f.write('this is file #%d.\n' % i)
                 f.close()
-                sftp.chmod('%s/file%d.txt' % (FOLDER, i), 0660)
+                sftp.chmod('%s/file%d.txt' % (FOLDER, i), o660)
 
             # now make sure every file is there, by creating a list of filenmes
             # and reading them in random order.
@@ -124,7 +124,7 @@ class BigSFTPTest (unittest.TestCase):
         write a 1MB file, with no linefeeds, using pipelining.
         """
         sftp = get_sftp()
-        kblob = ''.join([struct.pack('>H', n) for n in xrange(512)])
+        kblob = ''.join([struct.pack('>H', n) for n in range(512)])
         start = time.time()
         try:
             f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
@@ -165,7 +165,7 @@ class BigSFTPTest (unittest.TestCase):
 
     def test_4_prefetch_seek(self):
         sftp = get_sftp()
-        kblob = ''.join([struct.pack('>H', n) for n in xrange(512)])
+        kblob = ''.join([struct.pack('>H', n) for n in range(512)])
         try:
             f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
             f.set_pipelined(True)
@@ -181,13 +181,13 @@ class BigSFTPTest (unittest.TestCase):
             start = time.time()
             k2blob = kblob + kblob
             chunk = 793
-            for i in xrange(10):
+            for i in range(10):
                 f = sftp.open('%s/hongry.txt' % FOLDER, 'r')
                 f.prefetch()
                 base_offset = (512 * 1024) + 17 * random.randint(1000, 2000)
-                offsets = [base_offset + j * chunk for j in xrange(100)]
+                offsets = [base_offset + j * chunk for j in range(100)]
                 # randomly seek around and read them out
-                for j in xrange(100):
+                for j in range(100):
                     offset = offsets[random.randint(0, len(offsets) - 1)]
                     offsets.remove(offset)
                     f.seek(offset)
@@ -203,7 +203,7 @@ class BigSFTPTest (unittest.TestCase):
 
     def test_5_readv_seek(self):
         sftp = get_sftp()
-        kblob = ''.join([struct.pack('>H', n) for n in xrange(512)])
+        kblob = ''.join([struct.pack('>H', n) for n in range(512)])
         try:
             f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
             f.set_pipelined(True)
@@ -219,21 +219,21 @@ class BigSFTPTest (unittest.TestCase):
             start = time.time()
             k2blob = kblob + kblob
             chunk = 793
-            for i in xrange(10):
+            for i in range(10):
                 f = sftp.open('%s/hongry.txt' % FOLDER, 'r')
                 base_offset = (512 * 1024) + 17 * random.randint(1000, 2000)
                 # make a bunch of offsets and put them in random order
-                offsets = [base_offset + j * chunk for j in xrange(100)]
+                offsets = [base_offset + j * chunk for j in range(100)]
                 readv_list = []
-                for j in xrange(100):
+                for j in range(100):
                     o = offsets[random.randint(0, len(offsets) - 1)]
                     offsets.remove(o)
                     readv_list.append((o, chunk))
                 ret = f.readv(readv_list)
-                for i in xrange(len(readv_list)):
+                for i in range(len(readv_list)):
                     offset = readv_list[i][0]
                     n_offset = offset % 1024
-                    self.assertEqual(ret.next(), k2blob[n_offset:n_offset + chunk])
+                    self.assertEqual(next(ret), k2blob[n_offset:n_offset + chunk])
                 f.close()
             end = time.time()
             sys.stderr.write('%ds ' % round(end - start))
@@ -279,7 +279,7 @@ class BigSFTPTest (unittest.TestCase):
         verify that prefetch and readv don't conflict with each other.
         """
         sftp = get_sftp()
-        kblob = ''.join([struct.pack('>H', n) for n in xrange(512)])
+        kblob = ''.join([struct.pack('>H', n) for n in range(512)])
         try:
             f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
             f.set_pipelined(True)
@@ -318,7 +318,7 @@ class BigSFTPTest (unittest.TestCase):
         returned as a single blob.
         """
         sftp = get_sftp()
-        kblob = ''.join([struct.pack('>H', n) for n in xrange(512)])
+        kblob = ''.join([struct.pack('>H', n) for n in range(512)])
         try:
             f = sftp.open('%s/hongry.txt' % FOLDER, 'w')
             f.set_pipelined(True)
@@ -367,7 +367,7 @@ class BigSFTPTest (unittest.TestCase):
         k32blob = (32 * 1024 * 'x')
         try:
             f = sftp.open('%s/hongry.txt' % FOLDER, 'w', 128 * 1024)
-            for i in xrange(32):
+            for i in range(32):
                 f.write(k32blob)
             f.close()
             
diff --git a/tests/test_transport.py b/tests/test_transport.py
index 6c62b3e3..69fdbbb2 100644
--- a/tests/test_transport.py
+++ b/tests/test_transport.py
@@ -158,7 +158,7 @@ class TransportTest(ParamikoTest):
             pass
             
     def test_2_compute_key(self):
-        self.tc.K = 123281095979686581523377256114209720774539068973101330872763622971399429481072519713536292772709507296759612401802191955568143056534122385270077606457721553469730659233569339356140085284052436697480759510519672848743794433460113118986816826624865291116513647975790797391795651716378444844877749505443714557929L
+        self.tc.K = 123281095979686581523377256114209720774539068973101330872763622971399429481072519713536292772709507296759612401802191955568143056534122385270077606457721553469730659233569339356140085284052436697480759510519672848743794433460113118986816826624865291116513647975790797391795651716378444844877749505443714557929
         self.tc.H = unhexlify('0C8307CDE6856FF30BA93684EB0F04C2520E9ED3')
         self.tc.session_id = self.tc.H
         key = self.tc._compute_key('C', 32)
@@ -406,7 +406,7 @@ class TransportTest(ParamikoTest):
         chan.close()
         
         # allow a few seconds for the rekeying to complete
-        for i in xrange(50):
+        for i in range(50):
             if self.tc.H != self.tc.session_id:
                 break
             time.sleep(0.1)
@@ -659,7 +659,7 @@ class TransportTest(ParamikoTest):
             
             def run(self):
                 try:
-                    for i in xrange(1, 1+self.iterations):
+                    for i in range(1, 1+self.iterations):
                         if self.done_event.isSet():
                             break
                         self.watchdog_event.set()
diff --git a/tests/test_util.py b/tests/test_util.py
index 7e656df8..858dedba 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -101,7 +101,7 @@ class UtilTest(ParamikoTest):
 
     def test_2_parse_config(self):
         global test_config_file
-        f = cStringIO.StringIO(test_config_file)
+        f = StringIO(test_config_file)
         config = paramiko.util.parse_ssh_config(f)
         self.assertEquals(config._config,
             [{'host': ['*'], 'config': {}}, {'host': ['*'], 'config': {'identityfile': ['~/.ssh/id_rsa'], 'user': 'robey'}},
@@ -111,7 +111,7 @@ class UtilTest(ParamikoTest):
 
     def test_3_host_config(self):
         global test_config_file
-        f = cStringIO.StringIO(test_config_file)
+        f = StringIO(test_config_file)
         config = paramiko.util.parse_ssh_config(f)
 
         for host, values in {
@@ -138,7 +138,7 @@ class UtilTest(ParamikoTest):
 
     def test_4_generate_key_bytes(self):
         x = paramiko.util.generate_key_bytes(SHA, 'ABCDEFGH', 'This is my secret passphrase.', 64)
-        hex = ''.join(['%02x' % ord(c) for c in x])
+        hex = ''.join(['%02x' % byte_ord(c) for c in x])
         self.assertEquals(hex, '9110e2f6793b69363e58173e9436b13a5a4b339005741d5c680e505f57d871347b4239f14fb5c46e857d5e100424873ba849ac699cea98d729e57b3e84378e8b')
 
     def test_5_host_keys(self):
@@ -172,7 +172,7 @@ Host *.example.com
 Host *
     Port 3333
     """
-        f = cStringIO.StringIO(test_config_file)
+        f = StringIO(test_config_file)
         config = paramiko.util.parse_ssh_config(f)
         host = 'www13.example.com'
         self.assertEquals(
@@ -216,7 +216,7 @@ Host space-delimited
 Host equals-delimited
     ProxyCommand=foo bar=biz baz
 """
-        f = cStringIO.StringIO(conf)
+        f = StringIO(conf)
         config = paramiko.util.parse_ssh_config(f)
         for host in ('space-delimited', 'equals-delimited'):
             self.assertEquals(
@@ -228,7 +228,7 @@ Host equals-delimited
         """
         ProxyCommand should perform interpolation on the value
         """
-        config = paramiko.util.parse_ssh_config(cStringIO.StringIO("""
+        config = paramiko.util.parse_ssh_config(StringIO("""
 Host specific
     Port 37
     ProxyCommand host %h port %p lol
@@ -264,7 +264,7 @@ Host www13.*
 Host *
     Port 3333
     """
-        f = cStringIO.StringIO(test_config_file)
+        f = StringIO(test_config_file)
         config = paramiko.util.parse_ssh_config(f)
         host = 'www13.example.com'
         self.assertEquals(
@@ -293,7 +293,7 @@ ProxyCommand foo=bar:%h-%p
                                                      'foo=bar:proxy-without-equal-divisor-22'}
         }.items():
 
-            f = cStringIO.StringIO(test_config_file)
+            f = StringIO(test_config_file)
             config = paramiko.util.parse_ssh_config(f)
             self.assertEquals(
                 paramiko.util.lookup_ssh_host_config(host, config),
@@ -323,7 +323,7 @@ IdentityFile id_dsa22
                       'identityfile': ['id_dsa0', 'id_dsa1', 'id_dsa22']}
         }.items():
 
-            f = cStringIO.StringIO(test_config_file)
+            f = StringIO(test_config_file)
             config = paramiko.util.parse_ssh_config(f)
             self.assertEquals(
                 paramiko.util.lookup_ssh_host_config(host, config),
@@ -338,5 +338,5 @@ IdentityFile id_dsa22
 AddressFamily inet
 IdentityFile something_%l_using_fqdn
 """
-        config = paramiko.util.parse_ssh_config(cStringIO.StringIO(test_config))
+        config = paramiko.util.parse_ssh_config(StringIO(test_config))
         assert config.lookup('meh') # will die during lookup() if bug regresses