forked from osmocom/wireshark
![Guy Harris](/assets/img/avatar_default.png)
build_label_func is a pointer type, pointing to a function that can be used to generate a label for a "Decode As" entry. There's no need to have pointers to those pointers; have register_decode_as_next_proto() take a build_label_func, not a build_label_func *, as its last argument, assign that value rather than dereferencing it, get rid of unnecessary casts, and fix the comment in epan/decode_as.h for that argument. Change-Id: Idc3cf18204c543a2191b122c8129b362562c0ecd Reviewed-on: https://code.wireshark.org/review/25773 Reviewed-by: Guy Harris <guy@alum.mit.edu>
269 lines
8.8 KiB
C
269 lines
8.8 KiB
C
/* packet-moldudp.c
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* Routines for MoldUDP dissection
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* Copyright 2012, Evan Huus <eapache@gmail.com>
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*
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* http://www.nasdaqtrader.com/content/technicalsupport/specifications/dataproducts/moldudp.pdf
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/expert.h>
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#include <epan/decode_as.h>
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void proto_register_moldudp(void);
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void proto_reg_handoff_moldudp(void);
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/* Initialize the protocol and registered fields */
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static int proto_moldudp = -1;
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static int hf_moldudp_session = -1;
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static int hf_moldudp_sequence = -1;
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static int hf_moldudp_count = -1;
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static int hf_moldudp_msgblk = -1;
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static int hf_moldudp_msgseq = -1;
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static int hf_moldudp_msglen = -1;
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static int hf_moldudp_msgdata = -1;
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#define MOLDUDP_SESSION_LEN 10
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#define MOLDUDP_SEQUENCE_LEN 4
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#define MOLDUDP_COUNT_LEN 2
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#define MOLDUDP_MSGLEN_LEN 2
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#define MOLDUDP_HEARTBEAT 0x0000
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/* Initialize the subtree pointers */
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static gint ett_moldudp = -1;
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static gint ett_moldudp_msgblk = -1;
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static expert_field ei_moldudp_msglen_invalid = EI_INIT;
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static expert_field ei_moldudp_count_invalid = EI_INIT;
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static dissector_table_t moldudp_payload_table;
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static void moldudp_prompt(packet_info *pinfo _U_, gchar* result)
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{
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g_snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Payload as");
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}
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/* Code to dissect a message block */
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static guint
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dissect_moldudp_msgblk(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
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guint offset, guint32 sequence)
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{
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proto_item *ti;
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proto_tree *blk_tree;
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guint16 msglen, real_msglen, whole_len;
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guint remaining;
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tvbuff_t* next_tvb;
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if (tvb_reported_length(tvb) - offset < MOLDUDP_MSGLEN_LEN)
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return 0;
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msglen = tvb_get_letohs(tvb, offset);
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remaining = tvb_reported_length(tvb) - offset - MOLDUDP_MSGLEN_LEN;
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if (msglen == 0)
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col_set_str(pinfo->cinfo, COL_INFO, "MoldUDP Messages (End Of Session)");
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if (tvb_reported_length(tvb) < (offset + MOLDUDP_MSGLEN_LEN))
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real_msglen = 0;
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else if (msglen <= remaining)
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real_msglen = msglen;
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else
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real_msglen = remaining;
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/* msglen and real_msglen only count the data section, and don't
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* include the two bytes for the length field itself. */
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whole_len = real_msglen + MOLDUDP_MSGLEN_LEN;
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ti = proto_tree_add_item(tree, hf_moldudp_msgblk,
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tvb, offset, whole_len, ENC_NA);
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blk_tree = proto_item_add_subtree(ti, ett_moldudp_msgblk);
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ti = proto_tree_add_uint(blk_tree, hf_moldudp_msgseq,
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tvb, offset, 0, sequence);
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PROTO_ITEM_SET_GENERATED(ti);
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ti = proto_tree_add_item(blk_tree, hf_moldudp_msglen,
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tvb, offset, MOLDUDP_MSGLEN_LEN, ENC_LITTLE_ENDIAN);
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if (msglen != real_msglen)
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expert_add_info_format(pinfo, ti, &ei_moldudp_msglen_invalid,
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"Invalid Message Length (claimed %u, found %u)",
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msglen, real_msglen);
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offset += MOLDUDP_MSGLEN_LEN;
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/* Functionality for choosing subdissector is controlled through Decode As as MoldUDP doesn't
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have a unique identifier to determine subdissector */
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next_tvb = tvb_new_subset_length(tvb, offset, real_msglen);
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if (!dissector_try_payload_new(moldudp_payload_table, next_tvb, pinfo, tree, FALSE, NULL))
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{
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proto_tree_add_item(blk_tree, hf_moldudp_msgdata,
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tvb, offset, real_msglen, ENC_NA);
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}
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return whole_len;
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}
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/* Code to actually dissect the packets */
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static int
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dissect_moldudp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
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{
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proto_item *ti;
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proto_tree *moldudp_tree;
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guint offset = 0;
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guint16 count, real_count = 0;
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guint32 sequence;
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/* Check that there's enough data */
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if (tvb_reported_length(tvb) < (MOLDUDP_SESSION_LEN +
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MOLDUDP_SEQUENCE_LEN +
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MOLDUDP_COUNT_LEN))
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return 0;
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/* Make entries in Protocol column and Info column on summary display */
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "MoldUDP");
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/* Clear the info column so it's sane if we crash. We fill it in later when
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* we've dissected more of the packet. */
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col_clear(pinfo->cinfo, COL_INFO);
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count = tvb_get_letohs(tvb, MOLDUDP_SESSION_LEN + MOLDUDP_SEQUENCE_LEN);
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if (count == MOLDUDP_HEARTBEAT)
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col_set_str(pinfo->cinfo, COL_INFO, "MoldUDP Heartbeat");
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else
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col_set_str(pinfo->cinfo, COL_INFO, "MoldUDP Messages");
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/* create display subtree for the protocol */
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ti = proto_tree_add_item(tree, proto_moldudp,
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tvb, offset, -1, ENC_NA);
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moldudp_tree = proto_item_add_subtree(ti, ett_moldudp);
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proto_tree_add_item(moldudp_tree, hf_moldudp_session,
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tvb, offset, MOLDUDP_SESSION_LEN, ENC_ASCII|ENC_NA);
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offset += MOLDUDP_SESSION_LEN;
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sequence = tvb_get_letohl(tvb, offset);
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proto_tree_add_item(moldudp_tree, hf_moldudp_sequence,
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tvb, offset, MOLDUDP_SEQUENCE_LEN, ENC_LITTLE_ENDIAN);
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offset += MOLDUDP_SEQUENCE_LEN;
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ti = proto_tree_add_item(moldudp_tree, hf_moldudp_count,
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tvb, offset, MOLDUDP_COUNT_LEN, ENC_LITTLE_ENDIAN);
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offset += MOLDUDP_COUNT_LEN;
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while (tvb_reported_length(tvb) >= offset + MOLDUDP_MSGLEN_LEN)
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{
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offset += dissect_moldudp_msgblk(tvb, pinfo, moldudp_tree,
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offset, sequence++);
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real_count++;
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}
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if (real_count != count)
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{
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expert_add_info_format(pinfo, ti, &ei_moldudp_count_invalid,
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"Invalid Message Count (claimed %u, found %u)",
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count, real_count);
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}
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/* Return the amount of data this dissector was able to dissect */
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return tvb_captured_length(tvb);
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}
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/* Register the protocol with Wireshark */
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void
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proto_register_moldudp(void)
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{
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/* Setup list of header fields */
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static hf_register_info hf[] = {
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{ &hf_moldudp_session,
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{ "Session", "moldudp.session", FT_STRING, BASE_NONE, NULL, 0,
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"The session to which this packet belongs.", HFILL }},
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{ &hf_moldudp_sequence,
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{ "Sequence", "moldudp.sequence", FT_UINT32, BASE_DEC, NULL, 0,
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"The sequence number of the first message in this packet.", HFILL }},
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{ &hf_moldudp_count,
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{ "Count", "moldudp.count", FT_UINT16, BASE_DEC, NULL, 0,
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"The number of messages contained in this packet.", HFILL }},
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{ &hf_moldudp_msgblk,
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{ "Message Block", "moldudp.msgblock", FT_NONE, BASE_NONE, NULL, 0,
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"A message.", HFILL }},
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{ &hf_moldudp_msglen,
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{ "Length", "moldudp.msglen", FT_UINT16, BASE_DEC, NULL, 0,
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"The length of this message.", HFILL }},
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{ &hf_moldudp_msgseq,
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{ "Sequence", "moldudp.msgseq", FT_UINT32, BASE_DEC, NULL, 0,
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"The sequence number of this message.", HFILL }},
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{ &hf_moldudp_msgdata,
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{ "Payload", "moldudp.msgdata", FT_BYTES, BASE_NONE, NULL, 0,
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"The payload data of this message.", HFILL }}
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};
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/* Setup protocol subtree array */
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static gint *ett[] = {
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&ett_moldudp,
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&ett_moldudp_msgblk
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};
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static ei_register_info ei[] = {
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{ &ei_moldudp_msglen_invalid, { "moldudp.msglen.invalid", PI_MALFORMED, PI_ERROR, "Invalid Message Length", EXPFILL }},
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{ &ei_moldudp_count_invalid, { "moldudp.count.invalid", PI_MALFORMED, PI_ERROR, "Invalid Count", EXPFILL }},
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};
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expert_module_t* expert_moldudp;
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/* Register the protocol name and description */
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proto_moldudp = proto_register_protocol("MoldUDP", "MoldUDP", "moldudp");
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/* Required function calls to register the header fields and subtrees used */
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proto_register_field_array(proto_moldudp, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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expert_moldudp = expert_register_protocol(proto_moldudp);
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expert_register_field_array(expert_moldudp, ei, array_length(ei));
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moldudp_payload_table = register_decode_as_next_proto(proto_moldudp, "MoldUDP Payload", "moldudp.payload", "MoldUDP Payload", moldudp_prompt);
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}
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void
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proto_reg_handoff_moldudp(void)
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{
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dissector_handle_t moldudp_handle;
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moldudp_handle = create_dissector_handle(dissect_moldudp, proto_moldudp);
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dissector_add_for_decode_as_with_preference("udp.port", moldudp_handle);
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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