[project @ robey@lag.net-20060723235649-5f757e44908ffb31]

attempt to implement support for kex-gex 'old' packet type, which is apparently used by putty (this would only affect paramiko in server mode)

2 files changed, 110 insertions, 17 deletions

diff --git a/paramiko/kex_gex.py b/paramiko/kex_gex.py
index e945c1f5..9f8848c8 100644
--- a/paramiko/kex_gex.py
+++ b/paramiko/kex_gex.py
@@ -31,7 +31,8 @@ from paramiko.message import Message
 from paramiko.ssh_exception import SSHException
 
 
-_MSG_KEXDH_GEX_GROUP, _MSG_KEXDH_GEX_INIT, _MSG_KEXDH_GEX_REPLY, _MSG_KEXDH_GEX_REQUEST = range(31, 35)
+_MSG_KEXDH_GEX_REQUEST_OLD, _MSG_KEXDH_GEX_GROUP, _MSG_KEXDH_GEX_INIT, \
+    _MSG_KEXDH_GEX_REPLY, _MSG_KEXDH_GEX_REQUEST = range(30, 35)
 
 
 class KexGex (object):
@@ -49,19 +50,25 @@ class KexGex (object):
         self.x = None
         self.e = None
         self.f = None
+        self.old_style = False
 
-    def start_kex(self):
+    def start_kex(self, _test_old_style=False):
         if self.transport.server_mode:
-            self.transport._expect_packet(_MSG_KEXDH_GEX_REQUEST)
+            self.transport._expect_packet(_MSG_KEXDH_GEX_REQUEST, _MSG_KEXDH_GEX_REQUEST_OLD)
             return
         # request a bit range: we accept (min_bits) to (max_bits), but prefer
         # (preferred_bits).  according to the spec, we shouldn't pull the
         # minimum up above 1024.
         m = Message()
-        m.add_byte(chr(_MSG_KEXDH_GEX_REQUEST))
-        m.add_int(self.min_bits)
-        m.add_int(self.preferred_bits)
-        m.add_int(self.max_bits)
+        if _test_old_style:
+            # only used for unit tests: we shouldn't ever send this
+            m.add_byte(chr(_MSG_KEXDH_GEX_REQUEST_OLD))
+            m.add_int(self.preferred_bits)
+        else:
+            m.add_byte(chr(_MSG_KEXDH_GEX_REQUEST))
+            m.add_int(self.min_bits)
+            m.add_int(self.preferred_bits)
+            m.add_int(self.max_bits)
         self.transport._send_message(m)
         self.transport._expect_packet(_MSG_KEXDH_GEX_GROUP)
 
@@ -74,6 +81,8 @@ class KexGex (object):
             return self._parse_kexdh_gex_init(m)
         elif ptype == _MSG_KEXDH_GEX_REPLY:
             return self._parse_kexdh_gex_reply(m)
+        elif ptype == _MSG_KEXDH_GEX_REQUEST_OLD:
+            return self._parse_kexdh_gex_request_old(m)
         raise SSHException('KexGex asked to handle packet type %d' % ptype)
 
 
@@ -132,6 +141,28 @@ class KexGex (object):
         self.transport._send_message(m)
         self.transport._expect_packet(_MSG_KEXDH_GEX_INIT)
 
+    def _parse_kexdh_gex_request_old(self, m):
+        # same as above, but without min_bits or max_bits (used by older clients like putty)
+        self.preferred_bits = m.get_int()
+        # smoosh the user's preferred size into our own limits
+        if self.preferred_bits > self.max_bits:
+            self.preferred_bits = self.max_bits
+        if self.preferred_bits < self.min_bits:
+            self.preferred_bits = self.min_bits
+        # generate prime
+        pack = self.transport._get_modulus_pack()
+        if pack is None:
+            raise SSHException('Can\'t do server-side gex with no modulus pack')
+        self.transport._log(DEBUG, 'Picking p (~ %d bits)' % (self.preferred_bits,))
+        self.g, self.p = pack.get_modulus(self.min_bits, self.preferred_bits, self.max_bits)
+        m = Message()
+        m.add_byte(chr(_MSG_KEXDH_GEX_GROUP))
+        m.add_mpint(self.p)
+        m.add_mpint(self.g)
+        self.transport._send_message(m)
+        self.transport._expect_packet(_MSG_KEXDH_GEX_INIT)
+        self.old_style = True
+
     def _parse_kexdh_gex_group(self, m):
         self.p = m.get_mpint()
         self.g = m.get_mpint()
@@ -162,9 +193,11 @@ class KexGex (object):
         hm.add(self.transport.remote_version, self.transport.local_version,
                self.transport.remote_kex_init, self.transport.local_kex_init,
                key)
-        hm.add_int(self.min_bits)
+        if not self.old_style:
+            hm.add_int(self.min_bits)
         hm.add_int(self.preferred_bits)
-        hm.add_int(self.max_bits)
+        if not self.old_style:
+            hm.add_int(self.max_bits)
         hm.add_mpint(self.p)
         hm.add_mpint(self.g)
         hm.add_mpint(self.e)
diff --git a/tests/test_kex.py b/tests/test_kex.py
index 2680853e..3ab95b07 100644
--- a/tests/test_kex.py
+++ b/tests/test_kex.py
@@ -35,18 +35,21 @@ class FakeRandpool (object):
     def get_bytes(self, n):
         return chr(0xcc) * n
 
+
 class FakeKey (object):
     def __str__(self):
         return 'fake-key'
     def sign_ssh_data(self, randpool, H):
         return 'fake-sig'
 
+
 class FakeModulusPack (object):
     P = 0xFFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFFL
     G = 2
     def get_modulus(self, min, ask, max):
         return self.G, self.P
 
+
 class FakeTransport (object):
     randpool = FakeRandpool()
     local_version = 'SSH-2.0-paramiko_1.0'
@@ -56,7 +59,7 @@ class FakeTransport (object):
 
     def _send_message(self, m):
         self._message = m
-    def _expect_packet(self, t):
+    def _expect_packet(self, *t):
         self._expect = t
     def _set_K_H(self, K, H):
         self._K = K
@@ -90,7 +93,7 @@ class KexTest (unittest.TestCase):
         kex.start_kex()
         x = '1E000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D4'
         self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
-        self.assertEquals(paramiko.kex_group1._MSG_KEXDH_REPLY, transport._expect)
+        self.assertEquals((paramiko.kex_group1._MSG_KEXDH_REPLY,), transport._expect)
 
         # fake "reply"
         msg = Message()
@@ -110,7 +113,7 @@ class KexTest (unittest.TestCase):
         transport.server_mode = True
         kex = KexGroup1(transport)
         kex.start_kex()
-        self.assertEquals(paramiko.kex_group1._MSG_KEXDH_INIT, transport._expect)
+        self.assertEquals((paramiko.kex_group1._MSG_KEXDH_INIT,), transport._expect)
 
         msg = Message()
         msg.add_mpint(69)
@@ -130,7 +133,7 @@ class KexTest (unittest.TestCase):
         kex.start_kex()
         x = '22000004000000080000002000'
         self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
-        self.assertEquals(paramiko.kex_gex._MSG_KEXDH_GEX_GROUP, transport._expect)
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_GROUP,), transport._expect)
 
         msg = Message()
         msg.add_mpint(FakeModulusPack.P)
@@ -139,7 +142,7 @@ class KexTest (unittest.TestCase):
         kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_GROUP, msg)
         x = '20000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D4'
         self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
-        self.assertEquals(paramiko.kex_gex._MSG_KEXDH_GEX_REPLY, transport._expect)
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_REPLY,), transport._expect)
 
         msg = Message()
         msg.add_string('fake-host-key')
@@ -153,12 +156,42 @@ class KexTest (unittest.TestCase):
         self.assertEquals(('fake-host-key', 'fake-sig'), transport._verify)
         self.assert_(transport._activated)
 
-    def test_4_gex_server(self):
+    def test_4_gex_old_client(self):
+        transport = FakeTransport()
+        transport.server_mode = False
+        kex = KexGex(transport)
+        kex.start_kex(_test_old_style=True)
+        x = '1E00000800'
+        self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_GROUP,), transport._expect)
+
+        msg = Message()
+        msg.add_mpint(FakeModulusPack.P)
+        msg.add_mpint(FakeModulusPack.G)
+        msg.rewind()
+        kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_GROUP, msg)
+        x = '20000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D4'
+        self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_REPLY,), transport._expect)
+
+        msg = Message()
+        msg.add_string('fake-host-key')
+        msg.add_mpint(69)
+        msg.add_string('fake-sig')
+        msg.rewind()
+        kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REPLY, msg)
+        H = 'A265563F2FA87F1A89BF007EE90D58BE2E4A4BD0'
+        self.assertEquals(self.K, transport._K)
+        self.assertEquals(H, paramiko.util.hexify(transport._H))
+        self.assertEquals(('fake-host-key', 'fake-sig'), transport._verify)
+        self.assert_(transport._activated)
+        
+    def test_5_gex_server(self):
         transport = FakeTransport()
         transport.server_mode = True
         kex = KexGex(transport)
         kex.start_kex()
-        self.assertEquals(paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, transport._expect)
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST_OLD), transport._expect)
 
         msg = Message()
         msg.add_int(1024)
@@ -168,7 +201,7 @@ class KexTest (unittest.TestCase):
         kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, msg)
         x = '1F0000008100FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF0000000102'
         self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
-        self.assertEquals(paramiko.kex_gex._MSG_KEXDH_GEX_INIT, transport._expect)
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_INIT,), transport._expect)
 
         msg = Message()
         msg.add_mpint(12345)
@@ -181,3 +214,30 @@ class KexTest (unittest.TestCase):
         self.assertEquals(H, paramiko.util.hexify(transport._H))
         self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
         self.assert_(transport._activated)
+
+    def test_6_gex_server_with_old_client(self):
+        transport = FakeTransport()
+        transport.server_mode = True
+        kex = KexGex(transport)
+        kex.start_kex()
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST, paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST_OLD), transport._expect)
+
+        msg = Message()
+        msg.add_int(2048)
+        msg.rewind()
+        kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_REQUEST_OLD, msg)
+        x = '1F0000008100FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF0000000102'
+        self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
+        self.assertEquals((paramiko.kex_gex._MSG_KEXDH_GEX_INIT,), transport._expect)
+
+        msg = Message()
+        msg.add_mpint(12345)
+        msg.rewind()
+        kex.parse_next(paramiko.kex_gex._MSG_KEXDH_GEX_INIT, msg)
+        K = 67592995013596137876033460028393339951879041140378510871612128162185209509220726296697886624612526735888348020498716482757677848959420073720160491114319163078862905400020959196386947926388406687288901564192071077389283980347784184487280885335302632305026248574716290537036069329724382811853044654824945750581L
+        H = 'B41A06B2E59043CEFC1AE16EC31F1E2D12EC455B'
+        x = '210000000866616B652D6B6579000000807E2DDB1743F3487D6545F04F1C8476092FB912B013626AB5BCEB764257D88BBA64243B9F348DF7B41B8C814A995E00299913503456983FFB9178D3CD79EB6D55522418A8ABF65375872E55938AB99A84A0B5FC8A1ECC66A7C3766E7E0F80B7CE2C9225FC2DD683F4764244B72963BBB383F529DCF0C5D17740B8A2ADBE9208D40000000866616B652D736967'
+        self.assertEquals(K, transport._K)
+        self.assertEquals(H, paramiko.util.hexify(transport._H))
+        self.assertEquals(x, paramiko.util.hexify(str(transport._message)))
+        self.assert_(transport._activated)