/* packet-PROTOABBREV.c * Routines for PROTONAME dissection * Copyright YEARS, YOUR_NAME * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: LICENSE */ /* * (A short description of the protocol including links to specifications, * detailed documentation, etc.) */ #include "config.h" /* Define the name for the logging domain (try to avoid collisions with existing domains) */ #define WS_LOG_DOMAIN "PROTOABBREV" /* Global header providing a minimum base set of required macros and APIs */ #include #if 0 /* "System" includes used only as needed */ #include #include #include ... #endif #include /* Required dissection API header */ #include /* Include only as needed */ #include /* Include only as needed */ #if 0 /* IF AND ONLY IF your protocol dissector exposes code to other dissectors * (which most dissectors don't need to do) then the 'public' prototypes and * data structures can go in the header file packet-PROTOABBREV.h. If not, then * a header file is not needed at all and this #include statement can be * removed. */ #include "packet-PROTOABBREV.h" #endif /* Some protocols may need code from other dissectors, as here for * ssl_dissector_add() */ #include "packet-tls.h" /* Prototypes */ /* (Required to prevent [-Wmissing-prototypes] warnings */ void proto_reg_handoff_PROTOABBREV(void); void proto_register_PROTOABBREV(void); /* Initialize the protocol and registered fields */ static int proto_PROTOABBREV; static int hf_FIELDABBREV; static expert_field ei_PROTOABBREV_EXPERTABBREV; static dissector_handle_t PROTOABBREV_handle; static dissector_handle_t PROTOABBREV_tls_handle; /* Global sample preference ("controls" display of numbers) */ static bool pref_hex; /* Global sample port preference - real port preferences should generally * default to "" (for a range) or 0 (for a single uint) unless there is an * IANA-registered (or equivalent) port for your protocol. */ #define PROTOABBREV_TLS_PORT 5678 static unsigned tls_port_pref = PROTOABBREV_TLS_PORT; #define PROTOABBREV_TCP_PORTS "1234" static range_t *tcp_port_range = PROTOABBREV_TCP_PORTS; /* Initialize the subtree pointers */ static int ett_PROTOABBREV; /* A sample #define of the minimum length (in bytes) of the protocol data. * If data is received with fewer than this many bytes it is rejected by * the current dissector. */ #define PROTOABBREV_MIN_LENGTH 8 /* Code to actually dissect the packets */ static int dissect_PROTOABBREV(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) { /* Set up structures needed to add the protocol subtree and manage it */ proto_item *ti, *expert_ti; proto_tree *PROTOABBREV_tree; /* Other misc. local variables. */ unsigned offset = 0; int len = 0; /*** HEURISTICS ***/ /* First, if at all possible, do some heuristics to check if the packet * cannot possibly belong to your protocol. This is especially important * for protocols directly on top of TCP or UDP where port collisions are * common place (e.g., even though your protocol uses a well known port, * someone else may set up, for example, a web server on that port which, * if someone analyzed that web server's traffic in Wireshark, would result * in Wireshark handing an HTTP packet to your dissector). * * For example: */ /* Check that the packet is long enough for it to belong to us. */ if (tvb_reported_length(tvb) < PROTOABBREV_MIN_LENGTH) return 0; /* Check that there's enough data present to run the heuristics. If there * isn't, reject the packet; it will probably be dissected as data and if * the user wants it dissected despite it being short they can use the * "Decode-As" functionality. If your heuristic needs to look very deep into * the packet you may not want to require *all* data to be present, but you * should ensure that the heuristic does not access beyond the captured * length of the packet regardless. */ if (tvb_captured_length(tvb) < MAX_NEEDED_FOR_HEURISTICS) return 0; /* Fetch some values from the packet header using tvb_get_*(). If these * values are not valid/possible in your protocol then return 0 to give * some other dissector a chance to dissect it. */ if ( TEST_HEURISTICS_FAIL ) return 0; /*** COLUMN DATA ***/ /* There are two normal columns to fill in: the 'Protocol' column which * is narrow and generally just contains the constant string 'PROTOABBREV', * and the 'Info' column which can be much wider and contain misc. summary * information (for example, the port number for TCP packets). * * If you are setting the column to a constant string, use "col_set_str()", * as it's more efficient than the other "col_set_XXX()" calls. * * If * - you may be appending to the column later OR * - you have constructed the string locally OR * - the string was returned from a call to val_to_str() * then use "col_add_str()" instead, as that takes a copy of the string. * * The function "col_add_fstr()" can be used instead of "col_add_str()"; it * takes "printf()"-like arguments. Don't use "col_add_fstr()" with a format * string of "%s" - just use "col_add_str()" or "col_set_str()", as it's * more efficient than "col_add_fstr()". * * For full details see section 1.4 of README.dissector. */ /* Set the Protocol column to the constant string of PROTOABBREV */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "PROTOABBREV"); #if 0 /* If you will be fetching any data from the packet before filling in * the Info column, clear that column first in case the calls to fetch * data from the packet throw an exception so that the Info column doesn't * contain data left over from the previous dissector: */ col_clear(pinfo->cinfo, COL_INFO); #endif /* Some protocols need to be parsed differently for packets sent to the * registered (server) port versus packets sent from the server port * to an ephemeral client port. */ if (value_is_in_range(tcp_port_range, pinfo->destport)) { col_set_str(pinfo->cinfo, COL_INFO, "XXX Request"); } else { col_set_str(pinfo->cinfo, COL_INFO, "XXX Reply"); } /*** PROTOCOL TREE ***/ /* Now we will create a sub-tree for our protocol and start adding fields * to display under that sub-tree. Most of the time the only functions you * will need are proto_tree_add_item() and proto_item_add_subtree(). * * NOTE: The offset and length values in the call to proto_tree_add_item() * define what data bytes to highlight in the hex display window when the * line in the protocol tree display corresponding to that item is selected. * * Supplying a length of -1 tells Wireshark to highlight all data from the * offset to the end of the packet. */ /* create display subtree for the protocol */ ti = proto_tree_add_item(tree, proto_PROTOABBREV, tvb, 0, -1, ENC_NA); PROTOABBREV_tree = proto_item_add_subtree(ti, ett_PROTOABBREV); /* Add an item to the subtree, see section 1.5 of README.dissector for more * information. */ expert_ti = proto_tree_add_item(PROTOABBREV_tree, hf_FIELDABBREV, tvb, offset, len, ENC_xxx); offset += len; /* Some fields or situations may require "expert" analysis that can be * specifically highlighted. */ if ( TEST_EXPERT_condition ) /* value of hf_FIELDABBREV isn't what's expected */ expert_add_info(pinfo, expert_ti, &ei_PROTOABBREV_EXPERTABBREV); /* Continue adding tree items to process the packet here... */ /* If this protocol has a sub-dissector call it here, see section 1.8 of * README.dissector for more information. */ /* Return the amount of data this dissector was able to dissect (which may * or may not be the total captured packet as we return here). */ return tvb_captured_length(tvb); } /* Register the protocol with Wireshark. * * This format is required because a script is used to build the C function that * calls all the protocol registration. */ void proto_register_PROTOABBREV(void) { module_t *PROTOABBREV_module; expert_module_t *expert_PROTOABBREV; /* Setup list of header fields See Section 1.5 of README.dissector for * details. */ static hf_register_info hf[] = { { &hf_FIELDABBREV, { "FIELDNAME", "FIELDFILTERNAME", FT_FIELDTYPE, FIELDDISPLAY, FIELDCONVERT, BITMASK, "FIELDDESCR", HFILL } } }; /* Setup protocol subtree array */ static int *ett[] = { &ett_PROTOABBREV }; /* Setup protocol expert items */ static ei_register_info ei[] = { { &ei_PROTOABBREV_EXPERTABBREV, { "PROTOABBREV.EXPERTABBREV", PI_GROUP, PI_SEVERITY, "EXPERTDESCR", EXPFILL } } }; /* Register the protocol name and description */ proto_PROTOABBREV = proto_register_protocol("PROTONAME", "PROTOSHORTNAME", "PROTOFILTERNAME"); /* Required function calls to register the header fields and subtrees */ proto_register_field_array(proto_PROTOABBREV, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); /* Required function calls to register expert items */ expert_PROTOABBREV = expert_register_protocol(proto_PROTOABBREV); expert_register_field_array(expert_PROTOABBREV, ei, array_length(ei)); /* Use register_dissector() here so that the dissector can be * found by name by other protocols, by Lua, by Export PDU, * by custom User DLT dissection, etc. Some protocols may require * multiple uniquely named dissectors that behave differently * depending on the caller, e.g. over TCP directly vs over TLS. */ PROTOABBREV_handle = register_dissector("PROTOABBREV", dissect_PROTOABBREV, proto_PROTOABBREV); PROTOABBREV_tls_handle = register_dissector("PROTOABBREV.tls", dissect_PROTOABBREV_tls, proto_PROTOABBREV); /* Register a preferences module (see section 2.6 of README.dissector * for more details). Registration of a prefs callback is not required * if there are no preferences that affect protocol registration (an example * of a preference that would affect registration is a port preference). * If the prefs callback is not needed, use NULL instead of * proto_reg_handoff_PROTOABBREV in the following. */ PROTOABBREV_module = prefs_register_protocol(proto_PROTOABBREV, proto_reg_handoff_PROTOABBREV); /* Register a preferences module under the preferences subtree. * Only use this function instead of prefs_register_protocol (above) if you * want to group preferences of several protocols under one preferences * subtree. * * Argument subtree identifies grouping tree node name, several subnodes can * be specified using slash '/' (e.g. "OSI/X.500" - protocol preferences * will be accessible under Protocols->OSI->X.500-> * preferences node. */ PROTOABBREV_module = prefs_register_protocol_subtree(const char *subtree, proto_PROTOABBREV, proto_reg_handoff_PROTOABBREV); /* Register a simple example preference */ prefs_register_bool_preference(PROTOABBREV_module, "show_hex", "Display numbers in Hex", "Enable to display numerical values in hexadecimal.", &pref_hex); /* Register an example port preference */ prefs_register_uint_preference(PROTOABBREV_module, "tls.port", "PROTOABBREV TLS Port", " PROTOABBREV TLS port if other than the default", 10, &tls_port_pref); } /* If this dissector uses sub-dissector registration add a registration routine. * This exact format is required because a script is used to find these * routines and create the code that calls these routines. * * If this function is registered as a prefs callback (see * prefs_register_protocol above) this function is also called by Wireshark's * preferences manager whenever "Apply" or "OK" are pressed. In that case, it * should accommodate being called more than once by use of the static * 'initialized' variable included below. * * This form of the reg_handoff function is used if you perform registration * functions which are dependent upon prefs. See below this function for a * simpler form which can be used if there are no prefs-dependent registration * functions. */ void proto_reg_handoff_PROTOABBREV(void) { static bool initialized = false; static int current_tls_port_pref; if (!initialized) { /* Simple port preferences like TCP can be registered as automatic * Decode As preferences. */ dissector_add_uint_range_with_preference("tcp.port", PROTOABBREV_TCP_PORTS, PROTOABBREV_handle); initialized = true; } else { /* If you perform registration functions which are dependent upon * prefs then you should de-register everything which was associated * with the previous settings and re-register using the new prefs * settings here. In general this means you need to keep track of * the value the preference had at the time you registered, which * can be saved using local statics in this function (proto_reg_handoff). */ ssl_dissector_delete(current_tls_port_pref, PROTOABBREV_tls_handle); } /* Some port preferences, like TLS, are more complicated and cannot * be done with auto preferences, because the TCP dissector has to call * TLS for the particular port as well as TLS calling this dissector. */ ssl_dissector_add(tls_port_pref, PROTOABBREV_tls_handle); current_tls_port = tls_port_pref; /* Some protocols dissect packets going to the server port differently * than packets coming from the server port. The current Decode As * value can be retrieved here. Note that auto preferences are always * a range, even if registered with dissector_add_uint_with_preference. */ tcp_port_range = prefs_get_range_value("PROTOABBREV", "tcp.port"); } #if 0 /* Simpler form of proto_reg_handoff_PROTOABBREV which can be used if there are * no prefs-dependent registration function calls. */ void proto_reg_handoff_PROTOABBREV(void) { dissector_add_uint_range_with_preference("tcp.port", PROTOABBREV_TCP_PORTS, PROTOABBREV_handle); } #endif /* * Editor modelines - https://www.wireshark.org/tools/modelines.html * * Local variables: * c-basic-offset: 4 * tab-width: 8 * indent-tabs-mode: nil * End: * * vi: set shiftwidth=4 tabstop=8 expandtab: * :indentSize=4:tabSize=8:noTabs=true: */