From Ted Percival:

I have updated the TELNET dissector to dissect encryption negotiation
commands as specified by RFC 2946.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@18187 f5534014-38df-0310-8fa8-9805f1628bb7

diff --git a/epan/dissectors/packet-telnet.c b/epan/dissectors/packet-telnet.c
index 2c39500557e1becb978ecddf56e22cea218ecee9..38a7ef7915d6b603746cafcddfabcb092755e68b 100644 (file)
--- a/epan/dissectors/packet-telnet.c
+++ b/epan/dissectors/packet-telnet.c
@@ -50,6 +50,9 @@ static int hf_telnet_auth_mod_cred_fwd = -1;
 static int hf_telnet_auth_mod_enc = -1;
 static int hf_telnet_auth_krb5_type = -1;
 
+static int hf_telnet_enc_cmd = -1;
+static int hf_telnet_enc_type = -1;
+
 static gint ett_telnet = -1;
 static gint ett_telnet_subopt = -1;
 static gint ett_status_subopt = -1;
@@ -593,6 +596,50 @@ dissect_rfc_subopt(packet_info *pinfo _U_, const char *optname _U_, tvbuff_t *tv
                       val_to_str(cmd, rfc_opt_vals, "Unknown (%u)"));
 }
 
+#define TN_ENC_IS              0
+#define TN_ENC_SUPPORT         1
+#define TN_ENC_REPLY           2
+#define TN_ENC_START           3
+#define TN_ENC_END             4
+#define TN_ENC_REQUEST_START   5
+#define TN_ENC_REQUEST_END     6
+#define TN_ENC_ENC_KEYID       7
+#define TN_ENC_DEC_KEYID       8
+static const value_string enc_cmd_vals[] = {
+       { TN_ENC_IS,            "IS" },
+       { TN_ENC_SUPPORT,       "SUPPORT" },
+       { TN_ENC_REPLY,         "REPLY" },
+       { TN_ENC_START,         "START" },
+       { TN_ENC_END,           "END" },
+       { TN_ENC_REQUEST_START, "REQUEST-START" },
+       { TN_ENC_REQUEST_END,   "REQUEST-END" },
+       { TN_ENC_ENC_KEYID,     "ENC_KEYID" },
+       { TN_ENC_DEC_KEYID,     "DEC_KEYID" },
+       { 0, NULL }
+};
+
+#define TN_ENCTYPE_NULL                        0
+#define TN_ENCTYPE_DES_CFB64           1
+#define TN_ENCTYPE_DES_OFB64           2
+#define TN_ENCTYPE_DES3_CFB64          3
+#define TN_ENCTYPE_DES3_OFB64          4
+#define TN_ENCTYPE_CAST5_40_CFB64      8
+#define TN_ENCTYPE_CAST5_40_OFB64      9
+#define TN_ENCTYPE_CAST128_CFB64       10
+#define TN_ENCTYPE_CAST128_OFB64       11
+static const value_string enc_type_vals[] = {
+    { TN_ENCTYPE_NULL,                 "NULL" },
+    { TN_ENCTYPE_DES_CFB64,            "DES_CFB64" },
+    { TN_ENCTYPE_DES_OFB64,            "DES_OFB64" },
+    { TN_ENCTYPE_DES3_CFB64,           "DES3_CFB64" },
+    { TN_ENCTYPE_DES3_OFB64,           "DES3_OFB64" },
+    { TN_ENCTYPE_CAST5_40_CFB64,       "CAST5_40_CFB64" },
+    { TN_ENCTYPE_CAST5_40_OFB64,       "CAST5_40_OFB64" },
+    { TN_ENCTYPE_CAST128_CFB64,                "CAST128_CFB64" },
+    { TN_ENCTYPE_CAST128_OFB64,                "CAST128_OFB64" },
+    { 0, NULL }
+};
+
 
 #define TN_AC_IS       0
 #define TN_AC_SEND     1
@@ -836,6 +883,79 @@ dissect_authentication_subopt(packet_info *pinfo, const char *optname _U_, tvbuf
        }
 }
 
+/* This function only uses the octet in the buffer at 'offset' */
+static void dissect_encryption_type(tvbuff_t *tvb, int offset, proto_tree *tree) {
+       guint8 etype;
+       etype = tvb_get_guint8(tvb, offset);
+       proto_tree_add_uint(tree, hf_telnet_enc_type, tvb, offset, 1, etype);
+}
+
+static void
+dissect_encryption_subopt(packet_info *pinfo, const char *optname _U_, tvbuff_t *tvb, int offset, int len, proto_tree *tree)
+{
+       guint8 ecmd, key_first_octet;
+
+       ecmd = tvb_get_guint8(tvb, offset);
+       proto_tree_add_uint(tree, hf_telnet_enc_cmd, tvb, offset, 1, ecmd);
+       
+       offset++;
+       len--;
+
+       switch(ecmd) {
+       case TN_ENC_IS:
+       case TN_ENC_REPLY:
+               /* encryption type, type-specific data ... */
+               if (len > 0) {
+                       dissect_encryption_type(tvb, offset, tree);
+                       offset++;
+                       len--;
+                       proto_tree_add_text(tree, tvb, offset, len, "Type-specific data");
+               }
+               break;
+
+       case TN_ENC_SUPPORT:
+               /* list of encryption types ... */
+               while (len > 0) {
+                       dissect_encryption_type(tvb, offset, tree);
+                       offset++;
+                       len--;
+               }
+               break;
+               
+       case TN_ENC_START:
+               /* keyid ... */
+               if (len > 0) {
+                       key_first_octet = tvb_get_guint8(tvb, offset);
+                       proto_tree_add_text(tree, tvb, offset, len, (key_first_octet == 0) ? "Default key" : "Key ID");
+               }
+               break;
+
+       case TN_ENC_END:
+               /* no data */
+               break;
+
+       case TN_ENC_REQUEST_START:
+               /* (optional) keyid */
+               if (len > 0)
+                       proto_tree_add_text(tree, tvb, offset, len, "Key ID (advisory)");
+               break;
+
+       case TN_ENC_REQUEST_END:
+               /* no data */
+               break;
+               
+       case TN_ENC_ENC_KEYID:
+       case TN_ENC_DEC_KEYID:
+               /* (optional) keyid - if not supplied, there are no more known keys */
+               if (len > 0)
+                       proto_tree_add_text(tree, tvb, offset, len, "Key ID");
+               break;
+
+       default:
+               proto_tree_add_text(tree, tvb, offset, len, "Unknown command");
+       }
+}
+
 static tn_opt options[] = {
   {
     "Binary Transmission",                     /* RFC 856 */
@@ -1108,7 +1228,7 @@ static tn_opt options[] = {
     &ett_enc_subopt,
     VARIABLE_LENGTH,
     1,
-    NULL                                       /* XXX - fill me in */
+    dissect_encryption_subopt
   },
   {
     "New Environment Option",                  /* RFC 1572 */
@@ -1151,7 +1271,7 @@ static tn_opt options[] = {
     VARIABLE_LENGTH,
     1,
     dissect_comport_subopt
-  },
+  }
   
 };
 
@@ -1556,7 +1676,12 @@ proto_register_telnet(void)
                { &hf_telnet_auth_krb5_type,
                { "Command", "telnet.auth.krb5.cmd", FT_UINT8, BASE_DEC,
                  VALS(auth_krb5_types), 0, "Krb5 Authentication sub-command", HFILL }},
-               
+       { &hf_telnet_enc_cmd,
+               { "Enc Cmd", "telnet.enc.cmd", FT_UINT8, BASE_DEC,
+                 VALS(enc_cmd_vals), 0, "Encryption command", HFILL }},
+       { &hf_telnet_enc_type,
+               { "Enc Type", "telnet.enc.type", FT_UINT8, BASE_DEC,
+                 VALS(enc_type_vals), 0, "Encryption type", HFILL }},
         };
        static gint *ett[] = {
                &ett_telnet,
@@ -1596,7 +1721,7 @@ proto_register_telnet(void)
                &ett_xauth_subopt,
                &ett_charset_subopt,
                &ett_rsp_subopt,
-               &ett_comport_subopt,
+               &ett_comport_subopt
        };
 
         proto_telnet = proto_register_protocol("Telnet", "TELNET", "telnet");