Split out bencode dissector and use it in the bzr dissector.

Change-Id: I5b2ef173faf7670fad64298d67f2aaf055b8d6d8
Signed-Off-By: Jelmer Vernooij <jelmer@samba.org>
Reviewed-on: https://code.wireshark.org/review/82
Reviewed-by: Evan Huus <eapache@gmail.com>
Tested-by: Evan Huus <eapache@gmail.com>

1 files changed, 327 insertions, 0 deletions

diff --git a/epan/dissectors/packet-bencode.c b/epan/dissectors/packet-bencode.c
new file mode 100644
index 0000000000..f4f61c71dd
--- /dev/null
+++ b/epan/dissectors/packet-bencode.c
@@ -0,0 +1,327 @@
+/* packet-bencode.c
+ * Routines for bencode dissection
+ * Copyright (C) 2004,2013 Jelmer Vernooij <jelmer@samba.org>
+ *
+ * $Id$
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * Copied from packet-pop.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include <glib.h>
+#include <epan/prefs.h>
+#include <epan/conversation.h>
+#include <epan/packet.h>
+#include <epan/strutil.h>
+
+#include "packet-tcp.h"
+
+static int proto_bencode = -1;
+
+static gint hf_bencode_str_length   = -1;
+static gint hf_bencode_str          = -1;
+static gint hf_bencode_int          = -1;
+static gint hf_bencode_dict         = -1;
+static gint hf_bencode_dict_entry   = -1;
+static gint hf_bencode_list         = -1;
+
+static gint ett_bencode_dict = -1;
+static gint ett_bencode_dict_entry = -1;
+static gint ett_bencode_list = -1;
+
+static int dissect_bencoding_str(tvbuff_t *tvb, packet_info *pinfo _U_,
+                                 int offset, int length, proto_tree *tree, proto_item *ti, int treeadd)
+{
+   guint8 ch;
+   int stringlen = 0, nextstringlen;
+   int used;
+   int izero = 0;
+
+   if (length<2) {
+      proto_tree_add_text(tree, tvb, offset, length, "Decode Aborted: Invalid String");
+      return -1;
+   }
+
+   used = 0;
+
+   while (length>=1) {
+      ch = tvb_get_guint8(tvb, offset+used);
+      length--;
+      used++;
+
+      if (ch==':' && used>1) {
+         if (stringlen>length || stringlen<0) {
+            proto_tree_add_text(tree, tvb, offset, length, "Decode Aborted: Invalid String Length");
+            return -1;
+         }
+         if (tree) {
+            proto_tree_add_uint(tree, hf_bencode_str_length, tvb, offset, used, stringlen);
+            proto_tree_add_item(tree, hf_bencode_str, tvb, offset+used, stringlen, ENC_ASCII|ENC_NA);
+
+            if (treeadd==1) {
+               proto_item_append_text(ti, " Key: %s", format_text((guchar *)tvb_memdup(wmem_packet_scope(), tvb, offset+used, stringlen), stringlen));
+            }
+            if (treeadd==2) {
+               proto_item_append_text(ti, "  Value: %s", format_text((guchar *)tvb_memdup(wmem_packet_scope(), tvb, offset+used, stringlen), stringlen));
+            }
+         }
+         return used+stringlen;
+      }
+
+      if (!izero && ch>='0' && ch<='9') {
+         if (ch=='0' && used==1) {
+            izero = 1;
+         }
+
+         nextstringlen = (stringlen * 10) + (ch - '0');
+         if (nextstringlen>=stringlen) {
+            stringlen = nextstringlen;
+            continue;
+         }
+      }
+
+      proto_tree_add_text(tree, tvb, offset, length, "Decode Aborted: Invalid String");
+      return -1;
+   }
+
+   proto_tree_add_text(tree, tvb, offset, length, "Truncated Data");
+   return -1;
+}
+
+static int dissect_bencoding_int(tvbuff_t *tvb, packet_info *pinfo _U_,
+                                 int offset, int length, proto_tree *tree, proto_item *ti, int treeadd)
+{
+   gint32 ival=0;
+   int neg = 0;
+   int izero = 0;
+   int used;
+   guint8 ch;
+
+   if (length<3) {
+      proto_tree_add_text(tree, tvb, offset, length, "Decode Aborted: Invalid Integer");
+      return -1;
+   }
+
+   length--;
+   used = 1;
+
+   while (length>=1) {
+      ch = tvb_get_guint8(tvb, offset+used);
+      length--;
+      used++;
+
+      switch (ch) {
+      case 'e':
+         if (tree) {
+            if (neg) ival = -ival;
+            proto_tree_add_int(tree, hf_bencode_int, tvb, offset, used, ival);
+            if (treeadd==2) {
+               proto_item_append_text(ti, "  Value: %d", ival);
+            }
+         }
+         return used;
+
+      case '-':
+         if (used==2) {
+            neg = 1;
+            break;
+         }
+         /* Fall through */
+
+      default:
+         if (!(ch=='0' && used==3 && neg)) { /* -0 is invalid */
+            if (ch=='0' && used==2) { /* as is 0[0-9]+ */
+               izero = 1;
+               break;
+            }
+            if (!izero && ch>='0' && ch<='9') {
+               ival = (ival * 10) + (ch - '0');
+               break;
+            }
+         }
+
+         proto_tree_add_text(tree, tvb, offset, length, "Decode Aborted: Invalid Integer");
+         return -1;
+      }
+   }
+
+   proto_tree_add_text(tree, tvb, offset, length, "Truncated Data");
+   return -1;
+}
+
+static int dissect_bencoding_rec(tvbuff_t *tvb, packet_info *pinfo _U_,
+                                 int offset, int length, proto_tree *tree, int level, proto_item *treei, int treeadd)
+{
+   guint8 op;
+   int oplen = 0, op1len, op2len;
+   int used;
+
+   proto_item *ti = NULL, *td = NULL;
+   proto_tree *itree = NULL, *dtree = NULL;
+
+   if (level>10) {
+      proto_tree_add_text(tree, tvb, offset, -1, "Decode Aborted: Nested Too Deep");
+      return -1;
+   }
+   if (length<1) {
+      proto_tree_add_text(tree, tvb, offset, -1, "Truncated Data");
+      return length;
+   }
+
+   op = tvb_get_guint8(tvb, offset);
+   if (tree) {
+      oplen = dissect_bencoding_rec(tvb, pinfo, offset, length, NULL, level, NULL, 0);
+      if (oplen<0) oplen = length;
+   }
+
+   switch (op) {
+   case 'd':
+      if (tree) {
+         td = proto_tree_add_item(tree, hf_bencode_dict, tvb, offset, oplen, ENC_NA);
+         dtree = proto_item_add_subtree(td, ett_bencode_dict);
+      }
+
+      used = 1;
+      length--;
+
+      while (length>=1) {
+         op = tvb_get_guint8(tvb, offset+used);
+
+         if (op=='e') {
+            return used+1;
+         }
+
+         op1len = dissect_bencoding_str(tvb, pinfo, offset+used, length, NULL, NULL, 0);
+         if (op1len<0) {
+            if (dtree) {
+               proto_tree_add_text(dtree, tvb, offset+used, -1, "Decode Aborted: Invalid Dictionary Key");
+            }
+            return op1len;
+         }
+
+         op2len = -1;
+         if (length-op1len>2)
+            op2len = dissect_bencoding_rec(tvb, pinfo, offset+used+op1len, length-op1len, NULL, level+1, NULL, 0);
+         if (op2len<0) {
+            if (dtree) {
+               proto_tree_add_text(dtree, tvb, offset+used+op1len, -1, "Decode Aborted: Invalid Dictionary Value");
+            }
+            return op2len;
+         }
+
+         if (dtree) {
+            ti = proto_tree_add_item(dtree, hf_bencode_dict_entry, tvb, offset+used, op1len+op2len, ENC_NA);
+            itree = proto_item_add_subtree(ti, ett_bencode_dict_entry);
+
+            dissect_bencoding_str(tvb, pinfo, offset+used, length, itree, ti, 1);
+            dissect_bencoding_rec(tvb, pinfo, offset+used+op1len, length-op1len, itree, level+1, ti, 2);
+         }
+
+         used += op1len+op2len;
+         length -= op1len+op2len;
+      }
+      if (dtree) {
+         proto_tree_add_text(dtree, tvb, offset+used, -1, "Truncated Data");
+      }
+      return -1;
+
+   case 'l':
+      if (tree) {
+         ti = proto_tree_add_item(tree, hf_bencode_list, tvb, offset, oplen, ENC_NA);
+         itree = proto_item_add_subtree(ti, ett_bencode_list);
+      }
+
+      used = 1;
+      length--;
+
+      while (length>=1) {
+         op = tvb_get_guint8(tvb, offset+used);
+
+         if (op=='e') {
+            return used+1;
+         }
+
+         oplen = dissect_bencoding_rec(tvb, pinfo, offset+used, length, itree, level+1, ti, 0);
+         if (oplen<1) return oplen;
+
+         used += oplen;
+         length -= oplen;
+      }
+      if (itree) {
+         proto_tree_add_text(itree, tvb, offset+used, -1, "Truncated Data");
+      }
+      return -1;
+
+   case 'i':
+      return dissect_bencoding_int(tvb, pinfo, offset, length, tree, treei, treeadd);
+
+   default:
+      if (op>='1' && op<='9') {
+         return dissect_bencoding_str(tvb, pinfo, offset, length, tree, treei, treeadd);
+      }
+
+      proto_tree_add_text(tree, tvb, offset, -1, "Decode Aborted: Invalid Bencoding");
+   }
+
+   return -1;
+}
+
+static void dissect_bencoding(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
+{
+  dissect_bencoding_rec(tvb, pinfo, 0, tvb_length(tvb), tree, 0, NULL, 0);
+}
+
+void
+proto_register_bencode(void)
+{
+   static hf_register_info hf[] = {
+      { &hf_bencode_str_length,
+        { "String Length", "bencode.str.length", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }
+      },
+      { &hf_bencode_str,
+        { "String", "bencode.str", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }
+      },
+      { &hf_bencode_int,
+        { "Integer", "bencode.int", FT_INT32, BASE_DEC, NULL, 0x0, NULL, HFILL }
+      },
+      { &hf_bencode_dict,
+        { "Dictionary", "bencode.dict", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }
+      },
+      { &hf_bencode_dict_entry,
+        { "Entry", "bencode.dict.entry", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }
+      },
+      { &hf_bencode_list,
+        { "List", "bencode.list", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }
+      },
+   };
+
+   static gint *ett[] = {
+      &ett_bencode_dict,
+      &ett_bencode_dict_entry,
+      &ett_bencode_list,
+   };
+
+   proto_bencode = proto_register_protocol("Bencode", "Bencode", "bencode");
+   register_dissector("bencode", dissect_bencoding, proto_bencode);
+   proto_register_field_array(proto_bencode, hf, array_length(hf));
+   proto_register_subtree_array(ett, array_length(ett));
+}