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wireshark/epan/packet.h
Ronnie Sahlberg fcab322ada Some applications do very naughty things like reusing a port for a different protocol during different stages of an application cycle. 
This is very naughty and will cause problems when we have assigned a dissector to a dynamic port using conversation_set_dissector().


To make ethereal handle this case I have changed the try_conversation_dissector() to allow it to fail and return 0,   meaning   yes there is indeed a protocol registered for this conversation but that protocol rejected this packet.
(which only happens for "new" style dissectors, "old" style dissectors will never reject a packet that way)

When this happens  the decode_udp_port() helper will still allow other dissectors to be tried, in the hope that the conversation is now used for some other protocol and thus someone else might be able to decode the packet.


Update SNMP and TFTP dissectors to  check that even if there already is a conversation but that conversation does NOT have snmp/tftp registered as the dissector for it, then create a new conversation anyway and attach the proper dissector.

Since ethereal keeps track of which frame number a conversation started in, this actually works really well.



svn path=/trunk/; revision=14345
2005-05-11 10:40:53 +00:00

391 lines
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/* packet.h
* Definitions for packet disassembly structures and routines
*
* $Id$
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* 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.
*/
#ifndef __PACKET_H__
#define __PACKET_H__
/*
* If <inttypes.h> defines formats to be used to print 64-bit integers,
* include it.
*/
#ifdef INTTYPES_H_DEFINES_FORMATS
#include <inttypes.h>
#endif
#include "wiretap/wtap.h"
#include "proto.h"
#include "tvbuff.h"
#include "pint.h"
#include "to_str.h"
#include "value_string.h"
#include "column_info.h"
#include "frame_data.h"
#include "packet_info.h"
#include "column-utils.h"
#include "epan.h"
#define hi_nibble(b) (((b) & 0xf0) >> 4)
#define lo_nibble(b) ((b) & 0x0f)
/* Useful when you have an array whose size you can tell at compile-time */
#define array_length(x) (sizeof x / sizeof x[0])
/* Check whether the "len" bytes of data starting at "offset" is
* entirely inside the captured data for this packet. */
#define BYTES_ARE_IN_FRAME(offset, captured_len, len) \
((guint)(offset) + (guint)(len) > (guint)(offset) && \
(guint)(offset) + (guint)(len) <= (guint)(captured_len))
/* To pass one of two strings, singular or plural */
#define plurality(d,s,p) ((d) == 1 ? (s) : (p))
typedef struct _packet_counts {
gint sctp;
gint tcp;
gint udp;
gint icmp;
gint ospf;
gint gre;
gint netbios;
gint ipx;
gint vines;
gint other;
gint total;
gint arp;
} packet_counts;
/** Number of packet counts. */
#define PACKET_COUNTS_SIZE sizeof(packet_counts) / sizeof (gint)
/* Types of character encodings */
typedef enum {
CHAR_ASCII = 0, /* ASCII */
CHAR_EBCDIC = 1 /* EBCDIC */
} char_enc;
/* Struct for boolean enumerations */
typedef struct true_false_string {
char *true_string;
char *false_string;
} true_false_string;
/**
* A default set of true/false strings that dissectors can use for
* FT_BOOLEAN header fields.
**/
extern const true_false_string flags_set_truth;
extern void packet_init(void);
extern void packet_cleanup(void);
/* Handle for dissectors you call directly or register with "dissector_add()".
This handle is opaque outside of "packet.c". */
struct dissector_handle;
typedef struct dissector_handle *dissector_handle_t;
/* Hash table for matching port numbers and dissectors; this is opaque
outside of "packet.c". */
struct dissector_table;
typedef struct dissector_table *dissector_table_t;
/*
* Dissector that returns nothing.
*/
typedef void (*dissector_t)(tvbuff_t *, packet_info *, proto_tree *);
/*
* Dissector that returns:
*
* the amount of data in the protocol's PDU, if it was able to
* dissect all the data;
*
* 0, if the tvbuff doesn't contain a PDU for that protocol;
*
* the negative of the amount of additional data needed, if
* we need more data (e.g., from subsequent TCP segments) to
* dissect the entire PDU.
*/
typedef int (*new_dissector_t)(tvbuff_t *, packet_info *, proto_tree *);
typedef void (*DATFunc) (gchar *table_name, ftenum_t selector_type,
gpointer key, gpointer value, gpointer user_data);
typedef void (*DATFunc_handle) (gchar *table_name, gpointer value,
gpointer user_data);
typedef void (*DATFunc_table) (gchar *table_name, gchar *ui_name,
gpointer user_data);
/* Opaque structure - provides type checking but no access to components */
typedef struct dtbl_entry dtbl_entry_t;
extern dissector_handle_t dtbl_entry_get_handle (dtbl_entry_t *dtbl_entry);
extern dissector_handle_t dtbl_entry_get_initial_handle (dtbl_entry_t * entry);
extern void dissector_table_foreach_changed (char *name, DATFunc func,
gpointer user_data);
extern void dissector_table_foreach (char *name, DATFunc func,
gpointer user_data);
extern void dissector_all_tables_foreach_changed (DATFunc func,
gpointer user_data);
extern void dissector_table_foreach_handle(char *name, DATFunc_handle func,
gpointer user_data);
extern void dissector_all_tables_foreach_table (DATFunc_table func,
gpointer user_data);
/* a protocol uses the function to register a sub-dissector table */
extern dissector_table_t register_dissector_table(const char *name,
char *ui_name, ftenum_t type, int base);
/* Find a dissector table by table name. */
extern dissector_table_t find_dissector_table(const char *name);
/* Get the UI name for a sub-dissector table, given its internal name */
extern char *get_dissector_table_ui_name(const char *name);
/* Get the field type for values of the selector for a dissector table,
given the table's internal name */
extern ftenum_t get_dissector_table_selector_type(const char *name);
/* Get the base to use when displaying values of the selector for a
sub-dissector table, given the table's internal name */
extern int get_dissector_table_base(const char *name);
/* Add an entry to a uint dissector table. */
extern void dissector_add(const char *abbrev, guint32 pattern,
dissector_handle_t handle);
/* Delete the entry for a dissector in a uint dissector table
with a particular pattern. */
extern void dissector_delete(const char *name, guint32 pattern,
dissector_handle_t handle);
/* Change the entry for a dissector in a uint dissector table
with a particular pattern to use a new dissector handle. */
extern void dissector_change(const char *abbrev, guint32 pattern,
dissector_handle_t handle);
/* Reset an entry in a uint dissector table to its initial value. */
extern void dissector_reset(const char *name, guint32 pattern);
/* Look for a given value in a given uint dissector table and, if found,
call the dissector with the arguments supplied, and return TRUE,
otherwise return FALSE. */
extern gboolean dissector_try_port(dissector_table_t sub_dissectors,
guint32 port, tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
/* Look for a given value in a given uint dissector table and, if found,
return the dissector handle for that value. */
extern dissector_handle_t dissector_get_port_handle(
dissector_table_t sub_dissectors, guint32 port);
/* Add an entry to a string dissector table. */
extern void dissector_add_string(const char *name, gchar *pattern,
dissector_handle_t handle);
/* Delete the entry for a dissector in a string dissector table
with a particular pattern. */
extern void dissector_delete_string(const char *name, const gchar *pattern,
dissector_handle_t handle);
/* Change the entry for a dissector in a string dissector table
with a particular pattern to use a new dissector handle. */
extern void dissector_change_string(const char *name, gchar *pattern,
dissector_handle_t handle);
/* Reset an entry in a string sub-dissector table to its initial value. */
extern void dissector_reset_string(const char *name, const gchar *pattern);
/* Look for a given string in a given dissector table and, if found, call
the dissector with the arguments supplied, and return TRUE, otherwise
return FALSE. */
extern gboolean dissector_try_string(dissector_table_t sub_dissectors,
const gchar *string, tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
/* Look for a given value in a given string dissector table and, if found,
return the dissector handle for that value. */
extern dissector_handle_t dissector_get_string_handle(
dissector_table_t sub_dissectors, const gchar *string);
/* Add a handle to the list of handles that *could* be used with this
table. That list is used by code in the UI. */
extern void dissector_add_handle(const char *name, dissector_handle_t handle);
/* List of "heuristic" dissectors (which get handed a packet, look at it,
and either recognize it as being for their protocol, dissect it, and
return TRUE, or don't recognize it and return FALSE) to be called
by another dissector. */
typedef GSList *heur_dissector_list_t;
/** A protocol uses this function to register a heuristic sub-dissector list.
* Call this in the parent dissectors proto_register function.
*
* @param name the name of this protocol
* @param list the list of heuristic sub-dissectors to be registered
*/
extern void register_heur_dissector_list(const char *name,
heur_dissector_list_t *list);
/** Try all the dissectors in a given heuristic dissector list. This is done,
* until we find one that recognizes the protocol.
* Call this while the parent dissector running.
*
* @param sub_dissectors the sub-dissector list
* @param tvb the tv_buff with the (remaining) packet data
* @param pinfo the packet info of this packet (additional info)
* @param tree the protocol tree to be build or NULL
* @return TRUE if the packet was recognized by the sub-dissector (stop dissection here)
*/
extern gboolean dissector_try_heuristic(heur_dissector_list_t sub_dissectors,
tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
/** Type of a heuristic dissector, used in heur_dissector_add().
*
* @param tvb the tv_buff with the (remaining) packet data
* @param pinfo the packet info of this packet (additional info)
* @param tree the protocol tree to be build or NULL
* @return TRUE if the packet was recognized by the sub-dissector (stop dissection here)
*/
typedef gboolean (*heur_dissector_t)(tvbuff_t *tvb, packet_info *pinfo,
proto_tree *tree);
/** Add a sub-dissector to a heuristic dissector list.
* Call this in the proto_handoff function of the sub-dissector.
*
* @param name the name of the "parent" protocol, e.g. "tcp"
* @param dissector the sub-dissector to be registered
* @param proto the protocol id of the sub-dissector
*/
extern void heur_dissector_add(const char *name, heur_dissector_t dissector,
int proto);
/* Register a dissector. */
extern void register_dissector(const char *name, dissector_t dissector,
int proto);
extern void new_register_dissector(const char *name, new_dissector_t dissector,
int proto);
/* Get the short name of the protocol for a dissector handle. */
extern char *dissector_handle_get_short_name(dissector_handle_t handle);
/* Get the index of the protocol for a dissector handle. */
extern int dissector_handle_get_protocol_index(dissector_handle_t handle);
/* Find a dissector by name. */
extern dissector_handle_t find_dissector(const char *name);
/* Create an anonymous handle for a dissector. */
extern dissector_handle_t create_dissector_handle(dissector_t dissector,
int proto);
extern dissector_handle_t new_create_dissector_handle(new_dissector_t dissector,
int proto);
/* Call a dissector through a handle and if no dissector was found
* pass if over to the "data" dissector instead.
*/
extern int call_dissector(dissector_handle_t handle, tvbuff_t *tvb,
packet_info *pinfo, proto_tree *tree);
/* Call a dissector through a handle but if no dissector was found
* just return 0 and do not call the "data" dissector instead.
*/
extern int call_dissector_only(dissector_handle_t handle, tvbuff_t *tvb,
packet_info *pinfo, proto_tree *tree);
/* Do all one-time initialization. */
extern void dissect_init(void);
extern void dissect_cleanup(void);
/*
* Given a tvbuff, and a length from a packet header, adjust the length
* of the tvbuff to reflect the specified length.
*/
extern void set_actual_length(tvbuff_t *tvb, guint specified_len);
/* Allow protocols to register "init" routines, which are called before
we make a pass through a capture file and dissect all its packets
(e.g., when we read in a new capture file, or run a "filter packets"
or "colorize packets" pass over the current capture file). */
extern void register_init_routine(void (*func)(void));
/* Initialize all data structures used for dissection. */
extern void init_dissection(void);
/* Free data structures allocated for dissection. */
extern void cleanup_dissection(void);
/* Allow protocols to register a "cleanup" routine to be
* run after the initial sequential run through the packets.
* Note that the file can still be open after this; this is not
* the final cleanup. */
extern void register_postseq_cleanup_routine(void (*func)(void));
/* Call all the registered "postseq_cleanup" routines. */
extern void postseq_cleanup_all_protocols(void);
/* Allow dissectors to register a "final_registration" routine
* that is run like the proto_register_XXX() routine, but the end
* end of the epan_init() function; that is, *after* all other
* subsystems, liked dfilters, have finished initializing. This is
* useful for dissector registration routines which need to compile
* display filters. dfilters can't initialize itself until all protocols
* have registereed themselvs. */
extern void
register_final_registration_routine(void (*func)(void));
/* Call all the registered "final_registration" routines. */
extern void
final_registration_all_protocols(void);
/*
* Add a new data source to the list of data sources for a frame, given
* the tvbuff for the data source and its name.
*/
extern void add_new_data_source(packet_info *pinfo, tvbuff_t *tvb,
char *name);
/*
* Free up a frame's list of data sources.
*/
extern void free_data_sources(packet_info *pinfo);
/*
* Dissectors should never modify the packet data.
*/
extern void dissect_packet(epan_dissect_t *edt,
union wtap_pseudo_header *pseudo_header, const guchar *pd,
frame_data *fd, column_info *cinfo);
/* These functions are in packet-ethertype.c */
extern void capture_ethertype(guint16 etype, const guchar *pd, int offset,
int len, packet_counts *ld);
extern void ethertype(guint16 etype, tvbuff_t *tvb, int offset_after_ethertype,
packet_info *pinfo, proto_tree *tree, proto_tree *fh_tree,
int etype_id, int trailer_id, int fcs_len);
/*
* Dump layer/selector/dissector records in a fashion similar to the
* proto_registrar_dump_* routines.
*/
extern void dissector_dump_decodes(void);
#endif /* packet.h */
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