Differences

This shows you the differences between two versions of the page.

--- packet_network_monitoring_project:pnpmtrace [2025/11/02 13:23] – [Source Code] g8pzt
+++ packet_network_monitoring_project:pnpmtrace [2025/11/02 16:20] (current) – removed g8pzt
@@ Line 1: / Line 1: @@
-===== PNMPTRACE - JSON to Packet Trace Converter for PNMP =====
-==== What is PNMPTRACE? ====
-PNMPTRACE is a free open-source command line program which converts PNMP-format packet traces from JSON to a familiar ASCII "trace" format.
-==== What is PNMP? ====
-PNMP is the Packet Network Monitoring Project. The PNMP server receives packet traces and status data from participating XRouter and BPQ nodes, for the purposes of network monotoring, analysis, fault-finding and planning.
-The server, currently at 'node-api.packet.oarc.uk', makes the data available in a variety of forms, including an MQTT "hoseline" of raw data from the nodes (aka "reporters").  It is this data, from the endpoint at 'node-api.packet.oarc.uk/in/udp' that PNPMTRACE uses.
-==== Requirements ====
-  * GCC if you want to compile the program from the source below.
-  * mosquitto_sub (or any other suitable MQTT client). You can install this using 'sudo apt install mosquitto-clients'
-==== Executables ====
-[[https://wiki.oarc.uk:packet:pnmptrace-win32.zip|For 32-bit Windows]]
-[[https://wiki.oarc.uk/_media/packet:pnmptrace-x86-64.zip|For x86-64 Linux]]
-[[https://wiki.oarc.uk/_media/packet:pnmptrace-pi32.zip|For 32-bit ARM]]
-==== Notes ====
-This document assumes the use of Linux, and the MQTT client 'mosquitto_sub', but any MQTT client which outputs JSON to stdout could be used instead.
-==== How to Compile PNMPTRACE ====
-  * Copy and paste the C source code (below) into a file called pnmptrace.c
-  * Put pnmptrace.c into a directory of your choice.
-  * Open a terminal and change into that directory.
-  * Type: gcc -Wall -o "pnmptrace" "pnmptrace.c"
-  * Type: "ls" and you should see the compiled executable 'pnmptrace'.
-You can leave the executable where it is, or move it to the /bin directory, which will allow it to be run from anywhere without prepending "./".  You can move the executable like this:
-       sudo mv pnmptrace /bin
-==== How To Use PNMPTRACE ====
-  * Run mosquitto_sub, specifying the host and topic like so:
-      mosquitto_sub -h node-api.packet.oarc.uk -t in/udp
-  * You should see a constant stream of JSON data. If so, you can stop mosquitto_sub and move to the next step.  If you don't see any JSON, stop mosquitto_sub and re-check your command.
-  * Pipe the output of mosquitto_sub into PNMPTRACE like this:
-      mosquitto_sub -h node-api.packet.oarc.uk -t in/udp | ./pnmptrace
-      (omit the "./" if you moved pnptrace to /bin)
-You should now see the packet traces in a more familiar form.  The exact format can be tweaked using various command line options, as detailed in the next section.
-To read the MQTT from a file instead of mosquitto_sub, you would use a command like this, to pipe the output of "cat" into the input of pnmptrace:
-      cat mqtt.txt | ./pnmptrace
-You may wish to apply some "filters" to restrict the amount of data being displayed.  For instance, you might only be interested in UI frames, or frames from a particular station, or frames carrying a particular protocol such as IP.
-==== Filters and Display Options ====
-These are specified as arguments to the program. They cannot be changed on the fly.
-=== Summary of Options ===
-   Option            Description
-   -----------------------------------------------------------------
-     -3              Don't trace NetRom layer 3 or above
-     -4              Don't trace NetRom layer 4 or above
-     -a <callsign>   Show ALL frames to or from <callsign>
-     -c              Don't colourise the traces
-     -C              Include colour information in capture file
-     -f <callsign>   Show only frames addressed FROM <callsign>
-     -h              Show this message and exit
-     -H              Show header on separate line to trace
-     -i              Don't trace contents of INP3 routing unicasts
-     -j              Show the raw JSON before each trace
-     -k              Don't show L3RTT info field
-     -l              Suppress blank line between traces
-     -n              Don't trace contents of NetRom nodes broadcasts
-     -o <file>       Output trace to <file>
-     -p <portnum>    Show reports only from <portnum>
-     -P <protocol>   Show only frames with this L3 protocol
-     -q              No display when capturing to file (quiet)
-     -r <callsign>   Show reports only from <callsign>
-     -s              Suppress time stamp
-     -t <callsign>   Show only frames addressed TO <callsign>
-     -T <frametype>  Show only this AX25 frametype, e.g. "-T UI"
-     -u              Don't display UI frames
-     -w <width>      Display width (default 80 cols)
-     -W              Enable warnings of missing/bad JSON fields
-More than one option can be specified, but some combinations are pointless.  For example, if -3 is specified -i and -n are redundant.
-=== Display Options: ===
-<code>
-   Option            Description
-   -----------------------------------------------------------------
-     -c
-        Don't colourise the traces.  By default, traces are coloured
-        according to whether the link is RF or internet, and whether
-        the direction is "sent" or "received".  RF-originated traces
-        are displayed in pure red (transmit) or green (receive).
-        Internet-originated traces are displayed in pink (transmit) or
-        turquoise (receive).
-     -C
-        Include colour information in capture file.  This is off by
-        default, and is ignored if the '-c' option is specified.
-        Including colour information in the file allows it to be
-        played back in colour, but makes it harder to read with a text
-        editor.
-     -H
-        Show header (metadata) on a separate line to trace.  This is
-        off by default, as most people seem to prefer "one line per
-        packet".  If enabled, the display is less cryptic and includes
-        more information.
-     -j
-        Show the raw JSON prior to each trace.  This is off by default.
-        If enabled, the JSON data for each trace is displayed first,
-        followed by the decoded trace.  Included mainly for debugging.
-     -l
-        Suppress the blank line between traces.  Off by default.
-        Normally a blank line is output between each packet trace for
-        clarity.  However some people like a more cluttered display,
-        hence this option.
-     -o <filename>
-        Output the packet traces to <filename>.  If enabled, everything
-        that is displayed on screen is echoed to a capture file, whose
-        path/name is specified by this option.  The file is opened in
-        "overwrite" mode.  While capturing, the screen output can be
-        suppressed using the '-q' (quiet) option below.
-     -q
-        Suppresses the display while capturing to file.
-     -s
-        Suppress the packet time stamp.  Normally each packet trace
-        if prefixed with a time stamp of the form HH:MM:SS.  These
-        timestamps are generated by the reporting nodes, not by the
-        server, so there may be time differences between them.
-     -w <width>
-        Specify the display width (default 80 columns).  Most traces
-        should fit within 80 columns, but INP3 traces which include
-        several INP3 options might exceed this width.  By default,
-        these are neatly line-wrapped to fit 80 columns.  If you have a
-        wider display window you can specify the width using this
-        option.  The display will then line-wrap to fit the specified
-        width.  This is intended for displays wider than 80 columns,
-        not narrower.
-     -W
-        Enable warnings of missing or bad JSON fields.  This is mainly
-        intended for debugging purposes.
-</code>
-=== Filter Options: ===
-<code>
-     -3
-        Don't trace NetRom layer 3 or above.  If this option is
-        specified, packets containing NetRom layer 3/4 information,
-        including NODES broadcasts and INP3 data, will end with
-        "NET/ROM" and won't be traced any further.  You might use this
-        if for example you are only interested in the layer 2 data.
-        See also "-i", "-n" and "-4".
-     -4
-        Don't trace NetRom layer 4 or above.  If this option is
-        specified, NetRom layer 4 headers or protocol extensions are
-        not traced.
-     -a <callsign>
-        Show ALL frames to or from <callsign>.  If this filter is
-        specified, ONLY those frames which have AX25 source or
-        destination callsigns matching <callsign> are displayed.  This
-        can be used to watch all traffic into or out of a specific
-        node.
-     -f <callsign>
-        Show only frames addressed FROM <callsign>.  If this filter is
-        specified, ONLY those frames whose AX25 source callsign matches
-        <callsign> are displayed.  This filter can be combined with
-        other options for even tighter filtering.
-     -i
-        Don't trace contents of INP3 routing unicasts.  INP3 unicasts
-        can occupy a lot of space on screen. If you don't need to see
-        what they contain, the '-i' option suppresses decoding, so
-        all that is displayed is "NET/ROM INP3".
-     -k
-        Don't show L3RTT info field.  The payload of an L3RTT frame can
-        be up to 236 bytes, much of which is empty space. This wraps
-        untidily, so the '-k' option can be used to suppress it.
-     -n
-        Don't trace contents of NetRom 'NODES' broadcasts.  If this
-        option is used, nodes broadcasts display only "NET/ROM NODES".
-     -p <portnum>
-        Show reports only from <portnum>.  This filter is intended for
-        use in conjunction with the '-r', '-t', '-f' or '-a' filters.
-        For example, "r G8PZT -p 5" would show everything received or
-        sent on G8PZT's port 5.
-     -P <protocol>
-        Show only frames with the specified L3 protocol. For example
-        "-P IP" shows only IP over AX25 frames.  The recognised
-        protocols are as f0llows:
-        Mnemonic    Meaning
-        --------------------------------------------------------
-        "SEG"       Intermediate segment of a fragmented packet
-        "DATA"      No layer 3, i.e. payload contains normal data
-        "NET/ROM"   Payload contains NetRom/INP3 information
-        "IP"        Payload contains IP datagram or part thereof
-        "ARP"       Payload contains ARP data
-        "FLEXNET"   Payload contains Flexnet protocol
-        "?"         Unknown layer 3 protocol
-     -r <callsign>
-        Show reports only from <callsign>.  This filters traffic by the
-        "reporter" callsign, not the AX25 "to" or "from" fields. For
-        example "-r G8PZT" shows only the frames sent or overheard by
-        node G8PZT.
-     -t <callsign>
-        Show only frames addressed TO <callsign>.  If this filter is
-        specified, ONLY those frames whose AX25 destination callsign
-        matches <callsign> will be displayed.  Note that the same frame
-        may be reported by more than one node.
-     -T <frametype>
-        Show only frames with the specified AX25 frametype.  For example
-        "-T UI". The recognised frame types are as follows:
-        Mnemonic  Meaning
-        ---------------------------------------------------
-        "SABME"   Set Asynchronous Balanced Mode Extended
-        "C"       Non-extended connnect request (AKA SABM)
-        "D"       Disconnect Request
-        "DM"      Disconnected Mode / Busy
-        "UA"      Unnumbered Acknowledgement
-        "UI"      Unnumbered Information frame
-        "I"       Numbered information frame
-        "FRMR"    Frame Reject (serious error)
-        "RR"      Receiver Ready
-        "RNR"     Receiver Not Ready
-        "REJ"     Reject (Frame not the expected one)
-        "SREJ"    Selective Reject
-        "TEST"    Test of data link
-        "XID"     Exchange Identification
-        "?"       Unknown type
-     -u
-        Don't display UI frames.  This option may be useful if you
-        don't want to see beacons, APRS data, or nodes broadcasts.
-</code>
-Copyright (c) 2025 Paula Dowie
-==== Source Code ====
-<code c>
-/*
- * PNMPTRACE - A JSON to AX25 Packet Trace Decoder for the experimental
- *             Packet Network Monitoring Project (PNMP).
- *
- * Copyright (C) 2025 Paula Dowie G8PZT.
- *
- * 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 3 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, see
- * <https://www.gnu.org/licenses/>.
- *
- ***********************************************************************
- *
- * Purpose:
- *
- *    This program reads serialised JSON data from stdin, and outputs
- *    it to stdout and/or file in a familiar "packet trace" format.
- *
- *    The input JSON is expected to be in the PNMP (Packet Network
- *    Monitoring Project) format, as output by XRouter and BPQ nodes.
- *
- *    The data source may be the output of an MQTT client, or a file
- *    containing previously downloaded JSON. The MQTT client may connect
- *    with the main PNMP server for a network-wide view, or XRouter's
- *    internal MQTT broker for local monitoring.
- *
- *    The output format and packet filtering can be changed by command
- *    line options.
- *
- *
- * Usage:
- *
- *    pnpmtrace [options]
- *
- *    (use the "-help" option to list options)
- *
- *
- * Examples:
- *
- *    cat mqtt.txt | pnmptrace -H -n
- *
- *    mosquitto_sub -h node-api.packet.oarc.uk -t in/udp | pnmptrace
- *
- *
- * Limitations:
- *
- *    THIS IS ONLY A RUDIMENTARY JSON PARSER!  It is sufficient for the
- *    purpose of decoding JSON from the Packet Network Monitoring
- *    Project server, and nothing else.  One of the limitations is that
- *    it can not drill down into nested objects.
- *
- *
- * Versions:
- *
- *    Ver   Date     Comments
- *    -----------------------------------------------------------------
- *    1.0   24/10/25 Quick and dirty proof of concept. Decodes only
- *                   "L2Trace" objects. Requires an MQTT client such as
- *                   "mosquitto_sub" to download the JSON from the
- *                   server to stdout.
- *
- * To-Do:
- *
- *    - Possibly include an MQTT client, to make this self-contained,
- *      although that would prevent the program from using other
- *      data sources.
- *
- *    - Wildcard callsign filtering, if it would be any use?
- *
- *    - Filtering on multiple callsigns, e.g. -t g8pzt*,KIDDER*,M1BFP-1
- *
- *    - Filter by multiple frame types simultaneously, e.g. "-T I,UI"
- *
- *    - Decode L3RTT frame payload.
- *
- *    - Trace other report types when they have been implemented, e.g.
- *      where "@type" is "L3Trace", "L4Trace", "IpTrace" etc.
- *
- *    - Maybe someone could convert this to RUST, SLIME, PLURP or
- *      whatever strange language is the flavour of the moment, because
- *      nobody understands "C" any more :-)
- *
- * Notes:
- *
- *    This source is best viewed with a text editor such as geany or
- *    featherpad which colourises different code elements such as
- *    comments and strings.
- *
- *    Yes I know JSON field names should ideally be case sensitive, but
- *    the source data isn't always consistent!  Therefore case
- *    independent matching had to be used.
- *
- *    The terms "field" and "object" may not be consistent. It was a
- *    single-afternoon project.  Feel free to correct it!
- *
- *    No attempt has been made to optimise the code, to make it
- *    efficient, or pretty. It just does the job it was intended for.
- *
- *    Page width is 72 characters, as horizontal scrolling sucks.
- *
- *    I *know* that my coding style is not industry standard, so don't
- *    bother telling me. If you don't like it, tough! It's all mine,
- *    and it works for me.  If you can do better, why haven't you
- *    already done it? :-p
- * */
-#define _GNU_SOURCE  // Required for strcasestr()
-#ifdef WIN32
-#include <windows.h>
-#include <shlwapi.h>
-#define strcasestr StrStrI
-#endif
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <stdbool.h>
-#include <stdarg.h>
-#include <ctype.h>
-#include <time.h>
-static char VERSION[] = "1.0";
-static char Margin[] = "\n    ";  // Left margin for L3/L4 layers
-/* If filters are populated, they restrict the display to frames whose
- * fields match the filters. Unpopulated filters have no effect. The
- * compiler should set all these to null strings
- * */
-static char ReportFilter [16];   // Callsign to accept reports from
-static char SrcFilter [16];      // Source callsign filter
-static char DstFilter [16];      // Destination callsign filter
-static char AllFilter [16];      // Callsign to filter to/from
-static char ProtoFilter [16];    // Protocol to filter by
-static char TypeFilter [16];     // For filtering by L2Type
-static int  PortFilter = 0;      // For filtering by port number
-static int  DisplayWidth = 80;
-// TraceFlags control display options & filters
-static int  TraceFlags = 0x7ff;
-#define  TRACE_UI       0x01     // Unnumbered information frames (on)
-#define  TRACE_NETROM   0x02     // Trace Netrom L3/L4 layers (on)
-#define  TRACE_L3RTT    0x04     // Show Info field of L3RTT (on)
-#define  TRACE_NODES    0x08     // Trace into NODES broadcasts (on)
-#define  TRACE_INP3     0x10     // Trace into INP3 unicasts (on)
-#define  TRACE_L4       0x20     // Trace NetRom L4 headers (on)
-#define  TRACE_IP       0x40     // Trace IP headers (on)
-#define  TRACE_ARP      0x80     // Trace ARP packets (on)
-#define  TRACE_COLOR    0x100    // Trace in colour (on)
-#define  TRACE_STAMP    0x200    // Timestamp the trace (on)
-#define  TRACE_LBRK     0x400    // Line break between traces (on)
-#define  TRACE_HDRLIN   0x800    // Header & trace separate (off)
-#define  TRACE_JSON     0x1000   // Display JSON prior to trace (off)
-#define  TRACE_QUIET    0x2000   // Output to file only, no echo (off)
-#define  TRACE_COLOR2FILE  0x4000   // Send colour to file (off)
-#define  TRACE_WARNINGS 0x8000   // Display warnings of bad fields
-static char CaptureFile [256];   // Capture file name
-static FILE *FpCapture = NULL;   // For capturing output to file
-//######################################################################
-//                         JSON FUNCTIONS
-//######################################################################
-/**********************************************************************/
-/* Purpose:    Find a named JSON object by name
- * Called by:  json_findArray() and json_getValue()
- * Arguments:  Pointer to serialised JSON object string. Object name.
- * Actions:    Performs a case-independent sliding match, looking for
- *             the object name (including surrounding quotes) in the
- *             serialised JSON.  If found, the pointer is advanced over
- *             the name, the colon, and any whitespace, until the start
- *             of the object's value. If the object name is not found,
- *             or there is no colon after the nem, NULL is returned.
- * Affects:    Nothing
- * Returns:    Pointer to the start of the object's value in "json", or
- *             NULL if the object is not found.
- * Notes:      Name is case independent.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static char *json_findObject (const char *json, const char *name)
-   {
-   char  tmp [80], *cp;
-   sprintf (tmp, "\"%s\"", name);
-   if ((cp = strcasestr (json, tmp)) == NULL)
-      return (NULL); // Name not found
-   cp++; // Skip opening quote of the name
-   while (*cp && *cp != '"') cp++;  // find end of name
-   while (*cp && *cp != ':') cp++;   // find the colon
-   if (*cp != ':') return (NULL);   // No colon - so not a name
-   cp++; // skip the colon
-   while (isspace (*cp)) cp++;   // Skip space after colon
-   return (cp);   // Points at the object's value
-   }
-/**********************************************************************/
-/* Purpose:    Find a named JSON array by name.
- * Called by:  trace_nodes() and trace_inp3().
- * Arguments:  Pointer to serialised JSON object string. Array name.
- * Actions:    Performs a case-independent sliding match looking for the
- *             array name in the serialised JSON. If found, checks that
- *             the name actually belongs to an array.
- * Affects:    Nothing.
- * Returns:    Pointer to the opening square bracket in the "json"
- *             string, or NULL if the array is not found.
- * Notes:      Name is case independent.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static char *json_findArray (const char *json, char *name)
-   {
-   char  *cp;
-   if ((cp = json_findObject (json, name)) == NULL) return (NULL);
-   if (*cp != '[') return (NULL);
-   return (cp);   // Point at opening bracket
-   }
-/**********************************************************************/
-/* Purpose:    Get the value of a named JSON "field"
- * Called by:  Many places!
- * Arguments:  Pointer to serialised JSON object string, field name,
- *             Pointer to a string to receive the result, maximum chars
- *             to copy to result string.
- * Actions:    If the field is found, its string value, up to a maximum
- *             of "maxchars" is copied to the string pointed by "result"
- *             The quotes surrouunding string values are not copied.
- * Affects:    The string pointed by "result".
- * Returns:    Pointer to the first character after the field's value,
- *             or NULL if the field was not found.
- * Notes:      x
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static char *json_getValue (const char *json, const char *name,
-   char *result, int maxlen)
-   {
-   char  *cp;
-   int   string = 0;
-   if ((cp = json_findObject (json, name)) == NULL)
-      return (NULL); // Name not found
-   if (*cp == '"')   // If the first char of the value is a quote,
-      {
-      string = 1;    // it's a string literal.
-      cp++;          // Skip the quote character to point at value
-      }
-   if (string)       // If it's a string literal
-      {
-      while (*cp && *cp != '"')  // Copy everything between the quotes
-         {
-         if (maxlen-- > 0) *result++ = *cp;
-         cp++;
-         }
-      }
-   else  // Not a string literal, probably number or boolean
-      {
-      // Copy the value to "result"
-      while (*cp && (*cp == '-' || *cp == '.' || isalnum (*cp)))
-         {
-         if (maxlen-- > 0) *result++ = *cp;
-         cp++;
-         }
-      }
-   *result = 0;   // Terminate the result string
-   return (cp+1); // Pointer to first char AFTER the value
-   }
-/**********************************************************************/
-/* Purpose:    Get next JSON object from an array of objects
- * Called by:  trace_inp3() only. Ought to be used by decde_nodes()!
- * Arguments:  Pointer to a string containing serialised array, pointer
- *             to a string buffer to receive the object, maximum number
- *             of characters to copy.
- * Actions:    Ignores curent object and finds start of next, then
- *             copies the found object into "buffer", including its
- *             opening and closing braces.
- * Affects:    Contents of the string pointed by "buffer".
- * Returns:    Pointer to the opening brace of the found array element,
- *             or NULL if no next object found.
- * Notes:      Flat arrays of simple objects only. Does not allow braces
- *             within object values.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static const char *json_getNextArrayElement (const char *json,
-   char *buffer, int maxlen)
-   {
-   const char  *cp = json;
-   // Find end of current element
-   while (*cp && *cp != '}' && *cp != ']') cp++;
-   if (*cp != '}') return (NULL);   // Didn't find end
-   // Find start of next element
-   while (*cp && *cp != '{' && *cp != ']') cp++;
-   if (*cp != '{') return (NULL); // No next element
-   json = cp;  // Remember pointer to start of element
-   // Copy up to "maxlen" characters to "buffer", including braces.
-   while (*cp && maxlen-- > 0)
-      {
-      *buffer++ = *cp;
-      if (*cp == '}') break;
-      cp++;
-      }
-   *buffer = 0;   // terminate the output string
-   return (json); // Pointer to start of element
-   }
-//######################################################################
-//                       PACKET TRACE FUNCTIONS
-//######################################################################
-/**********************************************************************/
-/* Purpose:    Output to user and optional capture file
- * Called by:  Most functions.
- * Arguments:  Format string plus zero or more additional fields
- * Actions:    Prints the data to a string, then outputs it to screen
- *             (stdout) and/or the capture file.
- * Affects:    stdout, capture file or both.
- * Returns:    Number of characters printed.
- * Notes:      The output string must not exceed 4095 bytes, but that is
- *             highly unlikely to happen. Most calls only output a few
- *             characters.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static int uprintf (char *fmt, ...)
-   {
-   char buff [4096];
-   va_list arg;
-   va_start (arg, fmt);
-   vsprintf (buff, fmt, arg);
-   va_end (arg);
-   // Output to capture file if it is open
-   if (FpCapture)
-      {
-      fputs (buff, FpCapture);
-      fflush (FpCapture);
-      }
-   // Output to stdio if not in "quiet" mode
-   if ((TraceFlags & TRACE_QUIET) == 0) fputs (buff, stdout);
-   return (strlen (buff));
-   }
-/**********************************************************************/
-/* Purpose:    Decode and display a 'NODES' broadcast.
- * Called by:  trace_netromRoutingInfo() only.
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Displays the alias of the node making the broadcast,
- *             then loops through the "nodes" array, displaying details
- *             of each route.
- * Affects:    stdout only
- * Returns:    None
- * Notes:      Assumes "fromAlias" appears before "nodes" in the JSON
- *             string. This is necessary because the JSON parser is
- *             crude and case insensitive. It cannot distinguish between
- *             the field *name* "nodes" and the field *value* "NODES"
- *             which appears earlier in the string. This could be fixed
- *             by a better parser.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_nodes (const char *json)
-   {
-   char  tmp [80], *cp;
-   if ((TraceFlags & TRACE_NODES) == 0)
-      {
-      uprintf (" NODES Broadcast");
-      return; // Not wanted
-      }
-   if ((cp = json_getValue (json, "fromAlias", tmp, 6)) == NULL)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [missing 'fromAlias']");
-      return;
-      }
-   uprintf ("%sNODES Broadcast from %s:", Margin, tmp);
-   if ((cp = json_findArray (cp, "nodes")) == NULL)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [missing 'nodes' array]");
-      return;
-      }
-   // cp is pointing at the opening square bracket of nodes array
-   while (*cp)
-      {
-      // Format is "GE8PZT:BBS64 via GE8PZT qlty=20"
-      if (json_getValue (cp, "call", tmp, 9))
-         uprintf ("%s%s", Margin, tmp);
-      if (json_getValue (cp, "alias", tmp, 6))
-         uprintf (":%s", tmp);
-      if (json_getValue (cp, "via", tmp, 9))
-         uprintf (" via %s", tmp);
-      if (json_getValue (cp, "qual", tmp, 3))
-         uprintf (" qlty=%s", tmp);
-      while (*cp && *cp != '}') cp++;   // find end of node object
-      if (*cp) cp++;
-      }
-   }
-static int wrap (void)
-   {
-   uprintf ("%s    ", Margin);
-   return (8);
-   }
-/**********************************************************************/
-/* Purpose:    Decode and display an INP3 routing unicast
- * Called by:  trace_netromRoutingInfo() only.
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Loops through the "nodes" array, displaying details
- *             of each route.
- * Affects:    stdout only.
- * Returns:    None
- * Notes:      x
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_inp3 (const char *json)
-   {
-   char        object [1024], tmp [80];
-   const char  *cp;
-   if ((TraceFlags & TRACE_INP3) == 0)
-      {
-      uprintf (" INP3");
-      return;
-      }
-   uprintf ("%sINP3 Routing Unicast:", Margin);
-   if ((cp = json_findArray (json, "nodes")) == NULL)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [missing 'nodes' array]");
-      return;
-      }
-   // cp is now pointing at the opening square bracket of nodes array
-   while ((cp = json_getNextArrayElement (cp, object, 1023)) != NULL)
-      {
-      int   cols = 0;
-      // Minimum format is "GB7BDH    hp=2   tt=3"
-      if (json_getValue (object, "call", tmp, 9))
-         cols += uprintf ("%s%-9s", Margin, tmp);
-      if (json_getValue (object, "hops", tmp, 2))
-         cols += uprintf ("  hp=%-2s", tmp);
-      if (json_getValue (object, "tt", tmp, 5))
-         cols += uprintf ("  tt=%-5s", tmp);
-      // Optional fields
-      // "Alias=SWINDN 5128.75N 71582600.46E S/W=XRPi NODE PMS XRCHAT Ver=504k 25/10 06:20
-      if (json_getValue (object, "alias", tmp, 6))
-         cols += uprintf ("  Alias=%-6s", tmp);
-      if (json_getValue (object, "latitude", tmp, 20))
-         cols += uprintf (" %s", tmp);
-       if (json_getValue (object, "longitude", tmp, 20))
-         cols += uprintf (" %s", tmp);
-      if (json_getValue (object, "software", tmp, 20))
-         cols += uprintf (" S/W=%s", tmp);
-      // If could overflow 80-col line after this point
-      if (json_getValue (object, "version", tmp, 10))
-         {
-         if (cols+2+strlen (tmp) >= DisplayWidth) cols = wrap ();
-         cols += uprintf (" v%s", tmp);
-         }
-      if (json_getValue (object, "isNode", tmp, 5)
-      && strcmp (tmp, "true") == 0)
-         {
-         if ((cols + 5) >= DisplayWidth) cols = wrap ();
-         cols += uprintf (" NODE");
-         }
-      if (json_getValue (object, "isBBS", tmp, 5)
-      && strcmp (tmp, "true") == 0)
-         {
-         if ((cols + 4) >= DisplayWidth) cols= wrap ();
-         cols += uprintf (" BBS");
-         }
-      if (json_getValue (object, "isPMS", tmp, 5)
-      && strcmp (tmp, "true") == 0)
-         {
-         if ((cols + 4) >= DisplayWidth) cols= wrap ();
-         cols += uprintf (" PMS");
-         }
-      if (json_getValue (object, "isXRChat", tmp, 5)
-      && strcmp (tmp, "true") == 0)
-         {
-         if ((cols + 7) >= DisplayWidth) cols = wrap ();
-         cols += uprintf (" XRCHAT");
-         }
-      if (json_getValue (object, "isRTChat", tmp, 5)
-      && strcmp (tmp, "true") == 0)
-         {
-         if ((cols + 7) >= DisplayWidth) cols = wrap ();
-         cols += uprintf (" RTCHAT");
-         }
-      if (json_getValue (object, "isRMS", tmp, 5)
-      && strcmp (tmp, "true"))
-         {
-         if ((cols + 4) >= DisplayWidth) cols = wrap ();
-         cols += uprintf (" RMS");
-         }
-      if (json_getValue (object, "isDXClUS", tmp, 5)
-      && strcmp (tmp, "true") == 0)
-         {
-         if ((cols + 7) >= DisplayWidth) cols= wrap ();
-         cols += uprintf (" DXCLUS");
-         }
-      if (json_getValue (object, "timestamp", tmp, 40))
-         {
-         // There are two typs of timestamps currently in use...
-         if (strchr (tmp, 'T'))  // It's ISO-8601
-            {
-            // 2025-10-24T12:46:52Z
-            if ((cols + 21) >= DisplayWidth) cols= wrap ();
-            cols += uprintf (" %s", tmp);
-            }
-         else  // It's Unix time
-            {
-            time_t   t = atoi (tmp);
-            if (((unsigned)t) > 18000)
-               {
-               struct tm *tim = localtime (&t);
-               if ((cols + 12) >= DisplayWidth) cols= wrap ();
-               cols += uprintf (" %02d/%02d %02d:%02d",
-                  tim->tm_mday,  tim->tm_mon+1,
-                  tim->tm_hour,  tim->tm_min);
-               }
-            }
-         }
-      if (json_getValue (object, "tzMins", tmp, 8))
-         {
-         if (cols+3+strlen (tmp) >= DisplayWidth) cols = wrap ();
-         uprintf (" tz=%s", tmp);
-         }
-      }
-   }
-/**********************************************************************/
-/* Purpose:    Decode and display ARP headers
- * Called by:  process_json() for ptcl="ARP"
- * Arguments:  Pointer to string containing serialised JSON object.
- * Returns:    None
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_arp (const char *json)
-   {
-   char  tmp [80];
-   if ((TraceFlags & TRACE_ARP) == 0) return;
-   // Older software doesn't include these fields
-   if (json_getValue (json, "arpOp", tmp, 79) == NULL) return;
-   uprintf ("%sARP %s", Margin, tmp);
-   if (json_getValue (json, "arpHwType", tmp, 79))
-      uprintf (" hwtype=%s", tmp);
-   if (json_getValue (json, "arpHwLen", tmp, 79))
-      uprintf (" hwlen=%s", tmp);
-   if (json_getValue (json, "arpPtcl", tmp, 79))
-      uprintf (" prot=%s", tmp);
-   if (json_getValue (json, "arpSndAddr", tmp, 79))
-      uprintf ("%ssnd=%s", Margin, tmp);
-   if (json_getValue (json, "arpTgtAddr", tmp, 79))
-      uprintf (" tgt=%s", tmp);
-   if (json_getValue (json, "arpSndHw", tmp, 79))
-      uprintf (" snd_hw=%s", tmp);
-   if (json_getValue (json, "arpTgtHw", tmp, 79))
-      uprintf (" tgt_hw=%s", tmp);
-   }
-/**********************************************************************/
-/* Purpose:    Decode and display IP headers
- * Called by:  process_json() for ptcl="IP"
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Traces the main IP header fields, but not the payload
- * Affects:    stdout only
- * Returns:    None
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_ip (const char *json)
-   {
-   char     tmp [80], src [16], dst [16];
-   if ((TraceFlags & TRACE_IP) == 0) return;
-   // Older software doesn't include these fields
-   if (json_getValue (json, "ipFrom", src, 15) == NULL
-   || json_getValue (json, "ipTo", dst, 15) == NULL)
-      return;
-   // IP: 44.136.16.50 > 44.136.16.52 iplen=28 ttl=127 id=ABA0 ptcl=1 ICMP
-   uprintf ("%sIP: %s > %s", Margin, src, dst);
-   if (json_getValue (json, "ipLen", tmp, 6)) uprintf (" iplen=%s", tmp);
-   if (json_getValue (json, "ipTTL", tmp, 3)) uprintf (" ttl=%s", tmp);
-   if (json_getValue (json, "ipID", tmp, 6)) uprintf (" id=%s", tmp);
-   if (json_getValue (json, "ipPtcl", tmp, 6)) uprintf (" ptcl=%s", tmp);
-   if (json_getValue (json, "ipProto", tmp, 8)) uprintf (" %s", tmp);
-   }
-/**********************************************************************/
-/* Purpose:    Decode and display NetRom routing information frames
- * Called by:  trace_netrom() only.
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Checks the value of "l3Type", vcalling the appropriate
- *             function according to that value.
- * Returns:    None
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_netromRoutingInfo (const char *json)
-   {
-   char  type [16];
-   if (json_getValue (json, "type", type, 15) == NULL)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [missing 'type']");
-      return;
-      }
-   if (strcmp (type, "NODES") == 0) trace_nodes (json);
-   else if (strcmp (type, "INP3") == 0) trace_inp3 (json);
-   else if (TraceFlags & TRACE_WARNINGS)
-      uprintf (" [unknown 'type' '%s'", type);
-   // Future types go here
-   }
-/**********************************************************************/
-/* Purpose:    Trace a netrom routing poll
- * Called by:  x
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    x
- * Affects:    x
- * Returns:    x
- * Notes:      x
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_netromRoutingPoll (const char *json)
-   {
-   /// TODO: Populate me
-   }
-/**********************************************************************/
-/* Purpose:    Decode and display NetRom layer 4 segments
- * Called by:  trace_netromL3() only
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    For l4Type "PROT_EXT" this currently displays only the
- *             protocol type (if known), else the protocol family and
- *             protocol number (if protocol not known).
- *             If l4Type is not "PROT_EXT", the frame is either a L4
- *             transport frame, or a "Netrom Record Route" frame. Both
- *             types are traced. For L4 transport, only the headers are
- *             traced, the payloads are considered sensitive.
- * Affects:    stdout only.
- * Returns:    None
- * Notes:      Tracing of NCMP, NDP, GNET etc could be added if required
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_netromL4 (const char *json)
-   {
-   char  tmp [2048], l4type [16];
-   if ((TraceFlags & TRACE_L4) == 0) return;
-   //   NetRom L4 Frame Type
-   if (json_getValue (json, "l4type", l4type, 15) == 0)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [missing l4type]\n");
-      return;
-      }
-   if (strcmp (l4type, "unknown") == 0)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [unknown l4type]\n");
-      return;
-      }
-   if (strcmp (l4type, "PROT EXT") == 0)
-      {
-      uprintf (" <%s>", l4type);
-      if (json_getValue (json, "l4Family", tmp, 80))
-         uprintf (" pf=%s", tmp);
-      if (json_getValue (json, "l4Proto", tmp, 80))
-         uprintf (" prot=%s", tmp);
-      return;
-      }
-   if (strcmp (l4type, "IP") == 0
-   || strcmp (l4type, "NCMP") == 0
-   || strcmp (l4type, "NDP") == 0
-   || strcmp (l4type, "GNET") == 0)
-      {
-      /// TODO: Decode these properly one day
-      uprintf (" <%s>", l4type);
-      return;
-      }
-   if (strcmp (l4type, "NRR Request") == 0  // Netrom Record Route Request
-   || strcmp (l4type, "NRR Reply") == 0)  // Netrom Record Route Reply
-      {
-      uprintf (" <%s>", l4type);
-      if (json_getValue (json, "nrrId", tmp, 80))
-         uprintf (" id=%s", tmp);
-      if (json_getValue (json, "nrrRoute", tmp, 2047))
-         uprintf ("%sRoute: %s", Margin, tmp);
-      return;
-      }
-   if (json_getValue (json, "toCct", tmp, 8))
-      uprintf (" cct=%s", tmp);
-   if (strcmp (l4type, "CONN REQ") == 0
-   || strcmp (l4type, "CONN_REQX") == 0)
-      {
-      uprintf (" <%s>", l4type);
-      if (json_getValue (json, "window", tmp, 8))
-         uprintf (" w=%s", tmp);
-      if (json_getValue (json, "srcUser", tmp, 9))
-         uprintf ("\n          %s", tmp);
-      else return;
-      if (json_getValue (json, "srcNode", tmp, 9))
-         uprintf (" at %s", tmp);
-      if (json_getValue (json, "service", tmp, 8))
-         uprintf (" svc=%s", tmp);
-      if (json_getValue (json, "l4t1", tmp, 8))
-         uprintf (" t/o=%s", tmp);
-      if (json_getValue (json, "bpqSpy", tmp, 8))
-         uprintf (" bpqSpy=%s", tmp);
-      return;
-      }
-   if (strcmp (l4type, "CONN ACK") == 0)
-      {
-      uprintf (" <%s>", l4type);
-      if (json_getValue (json, "window", tmp, 8))
-         uprintf (" w=%s", tmp);
-      if (json_getValue (json, "fromCct", tmp, 8))
-         uprintf (" myCct=%s", tmp);
-      return; // ??
-      }
-   if (strcmp (l4type, "CONN NAK") == 0)
-      {
-      uprintf (" <%s>", l4type);
-      return; // ??
-      }
-   if (strcmp (l4type, "DREQ") == 0
-   || strcmp (l4type, "DACK") == 0)
-      {
-      uprintf (" <%s>", l4type);
-      return;
-      }
-   if (strcmp (l4type, "RSET") == 0)
-      {
-      uprintf (" <%s>", l4type);
-      if (json_getValue (json, "fromCct", tmp, 8))
-         uprintf (" myCct=%s", tmp);
-      return;
-      }
-   if (strcmp (l4type, "INFO") == 0)
-      {
-      uprintf (" <%s", l4type);
-      if (json_getValue (json, "txSeq", tmp, 8))
-         uprintf (" S%s", tmp);
-      if (json_getValue (json, "rxSeq", tmp, 8))
-         uprintf (" R%s", tmp);
-      uprintf (">");
-      if (json_getValue (json, "paylen", tmp, 8))
-         uprintf (" ilen=%s", tmp);
-      if (json_getValue (json, "payload", tmp, 2047))
-         uprintf (":%s%s", Margin, tmp);
-      }
-   else if (strcmp (l4type, "INFO ACK") == 0)
-      {
-      uprintf (" <%s", l4type);
-      if (json_getValue (json, "rxSeq", tmp, 8))
-         uprintf (" R%s", tmp);
-      uprintf (">");
-      }
-   if (json_getValue (json, "chokeFlag", tmp, 8))
-         uprintf (" <CHOKE>");
-   if (json_getValue (json, "nakFlag", tmp, 8))
-         uprintf (" <NAK>");
-   if (json_getValue (json, "moreFlag", tmp, 8))
-         uprintf (" <MORE>");
-   }
-/**********************************************************************/
-/* Purpose:    Trace L3RTT frames
- * Called by:  trace_netromL3() if l3Dest is "L3RTT"
- * Arguments:  Pointer to serialised JSON object.
- * Notes:      L3RTT is a "retrofit" to NetRom. It includes an L4 header
- *             which makes it look like an L4 INFO frame with circuit
- *             number, send and receive sequence numbers all zero. But
- *             it most definitely belongs in layer 3.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_l3rtt (const char *json)
-   {
-   char  tmp [512];
-   /* "l4type" should be "INFO", "toCct", "txSeq" and "rxSeq" should all
-    * be 0, if you want to bother to check them
-    * */
-   if (json_getValue (json, "paylen", tmp, 8))
-         uprintf (" ilen=%s", tmp);
-   if ((TraceFlags & TRACE_L3RTT) == 0) return;
-   // Payload chan be up to 236 chara, so it will wrap untidily
-   /// TODO: parse the payload & present the fields in a neater form
-   if (json_getValue (json, "payload", tmp, 511))
-      uprintf (":%s%s", Margin, tmp);
-   }
-/**********************************************************************/
-/* Purpose:    Display the L3 routing header, then trace layer 4
- * Called by:  trace_netrom() if l3Type is "netrom".
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Displays the L3 source and dest calls, and TTL, then
- *             traces layer 4.
- * Affects:    stdout only
- * Returns:    None
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void trace_netromL3 (const char *json)
-   {
-   char tmp [16];
-   bool  isL3RTT;
-   if (json_getValue (json, "l3src", tmp, 10))
-      uprintf ("%sNTRM: %s", Margin, tmp); // Layer 3 source
-   if (json_getValue (json, "l3dst", tmp, 10))
-      uprintf (" to %s", tmp);       // layer 3 dest
-   isL3RTT = (strcmp (tmp, "L3RTT") == 0);
-   if (json_getValue (json, "ttl", tmp, 8))
-      uprintf (" ttl=%s", tmp);      // Layer 3 time to live
-   if (isL3RTT) trace_l3rtt (json);
-   else trace_netromL4 (json);
-   }
-/**********************************************************************/
-/* Purpose:    Trace NetRom (PID 0xCF) frames
- * Called by:  process_json() only.
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Calls the appropriate decoder based on l3Type
- * Affects:    stdout only
- * Returns:    None
- * Created:    24/10/2025 by Paula Dowie G8PZT.*/
-/**********************************************************************/
-static void trace_netrom (const char *json)
-   {
-   char  tmp [80];
-   if ((TraceFlags & TRACE_NETROM) == 0) return;
-   if (json_getValue (json, "l3Type", tmp, 79) == 0)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         uprintf (" [missing 'l3Type']");
-      return;
-      }
-   if (strcmp (tmp, "NetRom") == 0) trace_netromL3 (json);
-   else if (strcmp (tmp, "Routing info") == 0)
-      trace_netromRoutingInfo (json);
-   else if (strcmp (tmp, "Routing poll") == 0)
-      trace_netromRoutingPoll (json);
-   else if (TraceFlags & TRACE_WARNINGS)
-      uprintf (" [unknown 'l3type': '%s'", tmp);
-   }
-/**********************************************************************/
-/* Purpose:    Process a serialised JSON object.
- * Called by:  main() only.
- * Arguments:  Pointer to string containing serialised JSON object.
- * Actions:    Extracts values from the JSON string, applies filters,
- *             sets trace colours, traces AX25 layer2 frame and
- *             optionally into the layers above.
- * Affects:    stdout only.
- * Returns:    None
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void process_json (const char *json)
-   {
-   char  tmp [1024], reporter [16], portnum [16], src [16], dst [16];
-   char  l2type [8], dirn [8], isRF [8], ptcl [8];
-   if (json_getValue (json, "@type", tmp, 80) == 0)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         printf ("[missing '@type']\n");
-      return;
-      }
-   /// TODO: Test for and process other report types here if desired
-   if (strcmp (tmp, "L2Trace") != 0) return;
-   // Extract some mandatory fields
-   if (json_getValue (json, "reportFrom", reporter, 15) == NULL
-   || json_getValue (json, "port", portnum, 15) == NULL
-   || json_getValue (json, "srce", src, 15) == NULL
-   || json_getValue (json, "dest", dst, 15) == NULL
-   || json_getValue (json, "l2Type", l2type, 7) == NULL)
-      {
-      if (TraceFlags & TRACE_WARNINGS)
-         printf ("[Mandatory field missing]\n");
-      return;
-      }
-   // Extract some of the optional values.
-   if (json_getValue (json, "dirn", dirn, 4) == NULL) *dirn = 0;
-   if (json_getValue (json, "isRF", isRF, 4) == NULL) *isRF = 0;
-   if (json_getValue (json, "ptcl", ptcl, 7) == NULL) *ptcl = 0;
-   if (strcmp (l2type, "UI") == 0
-   && (TraceFlags & TRACE_UI) == 0)
-      return;   // UI Not wanted
-   // Filter by reporting node
-   if (*ReportFilter // If report filter is enabled
-   && strcasecmp (reporter, ReportFilter) != 0) // and no match
-      return;  // Ignore this packet
-   // Filter by node's port number
-   if (PortFilter && atoi (portnum) != PortFilter) return;
-   // Filter by packet type
-   if (*TypeFilter
-   && strcasecmp (l2type, TypeFilter) != 0)
-      return;
-   // Filter by AX25 source call
-   if (*SrcFilter
-   && strcasecmp (src, SrcFilter) != 0)
-      return;
-   // Filter by AX25 source and destination calls
-   if (*DstFilter
-   && strcasecmp (dst, DstFilter) != 0)
-      return;
-   // Filter by either AX25 source or destination call
-   if (*AllFilter
-   && strcasecmp (dst, AllFilter) != 0
-   && strcasecmp (src, AllFilter) != 0)
-      return;
-   // Filter by protocol ID
-   if (*ProtoFilter
-   && (*ptcl == 0 || strcasecmp (ptcl, ProtoFilter)) != 0)
-      return;
-   if (TraceFlags & TRACE_COLOR)
-      {
-      const char *colorstr;
-      if (*isRF == 't') // True
-         {
-         switch (*dirn)
-            {
-            case 's':   colorstr = "\x1b[91m";   break; // red
-            case 'r':   colorstr = "\x1b[92m";   break; // green
-            default:    colorstr = "\x1b[93m";   break; // yellow
-            }
-         }
-      else if (*isRF == 'f')  // False
-         {
-         switch (*dirn)
-            {
-            case 's':   colorstr = "\x1b[38;2;255;150;150m";  break;
-            case 'r':   colorstr = "\x1b[38;2;50;255;150m";   break; // Cyan
-            default:    colorstr = "\x1b[94m";   break; // Blue
-            }
-         }
-      else  // Unknown RF/Inet status
-         colorstr = "\x1b[0m";  // white
-      /* Sending colour information to capture file allows it to be
-       * played back in colour but makes it difficult to read with a
-       * text editor. Therefore it is turned off by default.
-       * */
-      if (TraceFlags & TRACE_COLOR2FILE) uprintf ("%s", colorstr);
-      else printf ("%s", colorstr);
-      }
-   // If raw JSON wanted, print it before the trace (defaults off)
-   if (TraceFlags & TRACE_JSON) uprintf ("%s\n", json);
-   // Print a blank line between traces (dedaults on)
-   if (TraceFlags & TRACE_LBRK) uprintf ("\n");
-   // If timestamp is wanted (defaults on)
-   if (TraceFlags & TRACE_STAMP)
-      {
-      struct tm   *tp;
-      time_t      t;
-      if (json_getValue (json, "time", tmp, 20)) t = atoi (tmp);
-      else t = time (NULL);
-      tp = gmtime (&t);
-      uprintf ("%02d:%02d:%02d ",
-         tp->tm_hour, tp->tm_min, tp->tm_sec);
-      }
-   if (TraceFlags & TRACE_HDRLIN)
-      {
-      // Metadata and trace on separate lines for clarity
-      uprintf ("%s port %s", reporter, portnum);
-      if (*isRF) uprintf (*isRF == 't' ? " (RF)" : " (Non-RF)");
-      if (*dirn) uprintf (" %s", dirn);
-      uprintf (":\n  ");
-      }
-   else // Metadata and trace on one messy line
-      {
-      sprintf (tmp, "%s(%s)%c",
-         reporter, portnum, *dirn ? toupper (*dirn) : ' ');
-      uprintf ("%s ", tmp);
-      }
-   // Display L2 source, destination and type
-   uprintf ("%s>%s <%s", src, dst, l2type);
-   // The format of these varies with frame type...
-   if (json_getValue (json, "cr", tmp, 2)) uprintf (" %s", tmp);
-   if (json_getValue (json, "pf", tmp, 2)) uprintf (" %s", tmp);
-   if (json_getValue (json, "rseq", tmp, 3)) uprintf (" R%s", tmp);
-   if (json_getValue (json, "tseq", tmp, 3)) uprintf (" S%s", tmp);
-   uprintf (">");
-   // Display info field length and pid if present
-   if (json_getValue (json, "ilen", tmp, 10)) uprintf (" ilen=%s", tmp);
-   if (json_getValue (json, "pid", tmp, 10)) uprintf (" pid=%s", tmp);
-   if (*ptcl) uprintf (" %s", ptcl);
-   // Decode some payloads
-   if (*ptcl)
-      {
-      if (strcmp (ptcl, "NET/ROM") == 0) trace_netrom (json);
-      else if (strcmp (ptcl, "DATA") == 0)
-         {
-         // The "info" field is present only for "UI" frames
-         if (json_getValue (json, "info", tmp, 1023))
-            uprintf (":%s%s", Margin, tmp);
-         // The "icrc" field is present only for "I" frames
-         else if (json_getValue (json, "icrc", tmp, 8))
-            uprintf (" CRC=%s", tmp);
-         }
-      else if (strcmp (ptcl, "IP") == 0) trace_ip (json);
-      else if (strcmp (ptcl, "ARP") == 0) trace_arp (json);
-      /// TODO: Add flexnet
-      }
-   uprintf ("\n");
-   }
-/**********************************************************************/
-/* Purpose:    Display program help.
- * Called by:  main() if "-h" switch is found.
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-static void showHelp (void)
-   {
-   printf ("Usage: pmnptrace [options]\n\n");
-   printf ("Options:\n\n"
-   "   -3              Don't trace NetRom layer 3 or above\n"
-   "   -4              Don't trace NetRom layer 4 or above\n"
-   "   -a <callsign>   Show ALL frames to or from <callsign>\n"
-   "   -c              Don't colourise the traces\n"
-   "   -C              Include colour information in capture file\n"
-   "   -f <callsign>   Show only frames addressed FROM <callsign>\n"
-   "   -h              Show this message and exit\n"
-   "   -H              Show header on separate line to trace\n"
-   "   -i              Don't trace contents of INP3 routing unicasts\n"
-   "   -j              Show the raw JSON before each trace\n"
-   "   -k              Don't show L3RTT info field\n"
-   "   -l              Suppress blank line between traces\n"
-   "   -n              Don't trace contents of NetRom nodes broadcasts\n"
-   "   -o <file>       Output trace to <file>\n"
-   "   -p <portnum>    Show reports only from <portnum>\n"
-   "   -P <protocol>   Show only frames with this L3 protocol\n"
-   "   -q              No display when capturing to file (quiet)\n"
-   "   -r <callsign>   Show reports only from <callsign>\n"
-   "   -s              Suppress time stamp\n"
-   "   -t <callsign>   Show only frames addressed TO <callsign>\n"
-   "   -T <frametype>  Show only this AX25 frametype, e.g. \"-T UI\"\n"
-   "   -u              Don't display UI frames\n"
-   "   -w <width>      Display width (default 80 cols)\n"
-   "   -W              Enable warnings of missing/bad JSON fields\n\n");
-   }
-/**********************************************************************/
-/* Purpose:    Main function
- * Called by:  From command line
- * Arguments:  Program name, plus zero or more options
- * Actions:    Sets filters according to argument list, then loops to
- *             assemble un-named JSON objects from stdin, dispatching
- *             completed objects to the process_json() function.
- * Returns:    0 upon normal exit, else -1
- * Notes:      x
- * Created:    24/10/2025 by Paula Dowie G8PZT.
- * Modified:   */
-/**********************************************************************/
-int main (int argc, char *argv[])
-   {
-   char  buffer [4096], *cp;
-   int   braceLevel = 0;
-   int   c, ch, escaped = 0, inString=0;
-   uprintf ("\n\"pnmptrace\" JSON to AX25 Trace Decoder for PNMP\n");
-   uprintf ("Version %s, Copyright (C) 2025 G8PZT\n\n", VERSION);
-   if (argc < 2) uprintf ("Use 'pnmptrace -h' to display help, "
-      "Ctrl-C exits\n\n", argv [0]);
-    while (1)
-      {
-      if ((c = getopt (argc, argv, "34a:cijklnqsuhHWf:o:p:r:t:P:T:w:")) < 0)
-         break;   // End of options
-      switch (c)
-         {
-         case 'h':   showHelp ();                        return (0);
-         case 'c':   TraceFlags &= ~TRACE_COLOR;         break;
-         case 'C':   TraceFlags |= TRACE_COLOR2FILE;     break;
-         case 'u':   TraceFlags &= ~TRACE_UI;            break;
-         case 'i':   TraceFlags &= ~TRACE_INP3;          break;
-         case 'n':   TraceFlags &= ~TRACE_NODES;         break;
-         case '3':   TraceFlags &= ~TRACE_NETROM;        break;
-         case '4':   TraceFlags &= ~TRACE_L4;            break;
-         case 's':   TraceFlags &= ~TRACE_STAMP;         break;
-         case 'k':   TraceFlags &= ~TRACE_L3RTT;         break;
-         case 'l':   TraceFlags &= ~TRACE_LBRK;          break;
-         case 'j':   TraceFlags |= TRACE_JSON;           break;
-         case 'H':   TraceFlags |= TRACE_HDRLIN;         break;
-         case 'a':   strncpy (AllFilter, optarg, 15);    break;
-         case 'f':   strncpy (SrcFilter, optarg, 15);    break;
-         case 't':   strncpy (DstFilter, optarg, 15);    break;
-         case 'T':   strncpy (TypeFilter, optarg, 15);   break;
-         case 'r':   strncpy (ReportFilter, optarg, 15); break;
-         case 'o':   strncpy (CaptureFile, optarg, 255); break;
-         case 'p':   PortFilter = atoi (optarg);         break;
-         case 'P':   strncpy (ProtoFilter, optarg, 15);  break;
-         case 'q':   TraceFlags |= TRACE_QUIET;          break;
-         case 'w':   DisplayWidth = atoi (optarg);       break;
-         case 'W':   TraceFlags |= TRACE_WARNINGS;       break;
-         }
-      }
-   if (*CaptureFile)
-      {
-      if ((FpCapture = fopen (CaptureFile, "w")) == NULL)
-         {
-         printf ("Can't open capture file '%s'\n", CaptureFile);
-         return (-1);
-         }
-      printf ("Capturing traces to file '%s'\n", CaptureFile);
-      }
-   if (*ReportFilter)
-      uprintf ("Showing reports from node '%s' only\n", ReportFilter);
-   if (PortFilter)
-      uprintf ("Showing frames to/from port (%d) only\n",
-         PortFilter);
-   if (*SrcFilter)
-      uprintf ("Showing frames with L2 source call '%s' only\n",
-         SrcFilter);
-   if (*DstFilter)
-      uprintf ("Showing frames with L2 destination call '%s' only\n",
-         DstFilter);
-   if (*AllFilter)
-      uprintf ("Showing frames to/from L2 call '%s' only\n", AllFilter);
-   if (*TypeFilter)
-      uprintf ("Showing '%s' frames only\n", TypeFilter);
-   if (*ProtoFilter)
-      uprintf ("Showing frames with L3 protocol '%s' only\n",
-         ProtoFilter);
-   if ((TraceFlags & TRACE_UI) == 0) uprintf ("Not showing UI frames\n");
-   if ((TraceFlags & TRACE_NETROM) == 0)
-      uprintf ("Not decoding NODES broadcasts\n");
-   if ((TraceFlags & TRACE_INP3) == 0)
-      uprintf ("Not decoding INP3 unicasts\n");
-   if ((TraceFlags & TRACE_NETROM) == 0)
-      uprintf ("Not decoding NetRom Layer 3 or above\n");
-   if ((TraceFlags & TRACE_L4) == 0)
-      uprintf ("Not decoding NetRom Layer 4 or above\n");
-   if ((TraceFlags & TRACE_L3RTT) == 0)
-      uprintf ("Not showing L3RTT frame contents\n");
-   if (TraceFlags & TRACE_JSON) uprintf ("Including JSON data\n");
-   if ((TraceFlags & TRACE_STAMP) == 0)
-      uprintf ("Time stamp disabled\n");
-   cp = buffer;
-   while (1)   // Forever loop
-      {
-      // Get a char from stdin - blocking
-      if ((ch = getchar ()) == EOF) break;
-      if (braceLevel == 0) // Waiting for opening brace
-         {
-         if (ch == '{')    // Found the opening brace
-            {
-            braceLevel = 1;
-            cp = buffer;   // Point cp at start of object buffer
-            }
-         continue;
-         }
-      // If we get here, braceLevel is > 0
-      if (ch == '}')       // Possible end of object
-         {
-         if (!escaped            // If not in "escaped" mode,
-         && !inString            // and not within a string,
-         && --braceLevel == 0)   // and it is the final brace
-            {
-            *cp++ = 0;              // Terminate the string
-            process_json (buffer);  // Process the object
-            cp = buffer;            // Reset the pointer
-            continue;
-            }
-         }
-      *cp++ = ch;     // Copy the character to the object buffer
-      if (ch == '{'     // Possible start of object within object
-      && !escaped && !inString)
-         {
-         braceLevel++;
-         continue;
-         }
-      if (escaped)
-         {
-         escaped = 0;
-         continue;
-         }
-      else  // Not in escaped mode
-         {
-         if (ch == '\\')   // If it's the escape character
-            {
-            escaped = 1;   // Set escaped mode
-            continue;
-            }
-         }
-      // Not escape and not '\'
-      if (ch == '"') // Start of end of string
-         {
-         if (inString) inString = 0;
-         else inString = 1;
-         continue;
-         }
-      }  // end of while()
-   if (FpCapture) fclose (FpCapture);
-   return (0);
-   }
-</code>