New option -j / --json for the JSON output in the functions print_per_system_stats() and print_global_stats() by gsnw-sebast · Pull Request #379 · schweikert/fping

gsnw-sebast · 2025-02-09T14:52:51Z

A JSON output can be generated using the -j / --json option.
This can be extended with the -s option.

The json.c/.h are intended to simplify use somewhat.
On the one hand, it can be used to control the spaces for the output format and, on the other hand, the separators for the next data record.

The key value function only works with strings. If numbers are used, there is the function json_int_to_string()

gsnw-sebast · 2025-02-09T14:53:28Z

Was put on draft because the test is still missing and I wanted to wait for feedback first

coveralls · 2025-02-09T14:56:02Z

coverage: 81.744% (-6.1%) from 87.833%
when pulling c60f59d on gsnw:issue/164
into a237394 on schweikert:develop.

AthenaNetworks · 2025-02-12T02:36:52Z

Tested and confirmed working.

root@atlas:/opt/fping/sbin# ./fping --json -c 10 1.1.1.1 9.9.9.9
{
 "hosts": [
   {
     "host": "1.1.1.1",
     "xmt": "10",
     "rcv": "10",
     "loss": "0",
     "min": "0.413",
     "avg": "0.502",
     "max": "0.639"
   },
   {
     "host": "9.9.9.9",
     "xmt": "10",
     "rcv": "10",
     "loss": "0",
     "min": "11.5",
     "avg": "11.7",
     "max": "12.1"
   }
 ]

Tested various ways, seems to all work the way we need it to. This binary is actually going into production today, with the hopes this will be included in main/master in the future.

My C is a little rusty these days but I'm happy to help with this if I can.

The only thing I can suggest is adding a \n at the end of the payload because it does this }root@atlas:/opt/fping/sbin# but in reality this JSON is almost always going to be consumed by another process to parse it so this won't even matter.

There's also the question of whether you bother pretty printing it or just leaving it condensed (less characters to decode, technically more efficient).

Otherwise, perfect fit for us.

AthenaNetworks · 2025-02-12T03:15:55Z

We may have an issue here:

fping --json -C 10 -p 1000 -t 2000 -q 8.8.8.8 1.1.1.1

returns this:

{
  "hosts": [
    {
      "host": "8.8.8.8",
      "count": [

        "0": "12.4",
        "1": "12.3",
        "2": "12.4",
        "3": "12.3",
        "4": "12.4",
        "5": "12.2",
        "6": "12.2",
        "7": "12.4",
        "8": "12.4",
        "9": "12.5"
      ]
    },
    {
      "host": "1.1.1.1",
      "count": [

        "0": "0.439",
        "1": "0.447",
        "2": "0.531",
        "3": "0.471",
        "4": "0.565",
        "5": "0.516",
        "6": "0.410",
        "7": "0.343",
        "8": "0.384",
        "9": "0.370"
      ]
    }
  ]
}

However when I try to parse it:

Parse error on line 7:
...unt": [        "0": "12.2",        "1
---------------------^
Expecting 'EOF', '}', ',', ']', got ':'

Perhaps you should be returning:

"count": [
        "0.439",
        "0.447",
        "0.531",
        "0.471"
]

This parses as valid JSON and is basically handled the same way, foreach/for/etc over the count object.

AthenaNetworks · 2025-02-12T03:30:07Z

I've attached 3 diff's showing the changes I've made to produce a value JSON object.

fping.c.diff.txt
json.h.diff.txt
json.c.diff.txt

New output looks like this:

root@atlas:/opt/api-v2# /opt/fping/sbin/fping -C 10 -p 1000 -t 2000 -q 8.8.8.8 1.1.1.1 --json
{
  "hosts": [
    {
      "host": "8.8.8.8",
      "count": [

        "12.3",
        "12.3",
        "12.5",
        "12.4",
        "12.3",
        "12.2",
        "12.3",
        "12.3",
        "12.4",
        "12.2"
      ]
    },
    {
      "host": "1.1.1.1",
      "count": [

        "0.488",
        "0.602",
        "0.607",
        "0.380",
        "0.461",
        "0.511",
        "0.483",
        "0.503",
        "0.599",
        "0.461"
      ]
    }
  ]
}

schweikert · 2025-02-13T10:50:24Z

Thanks a lot for this!

Before we merge and before further work on the implementation is done, I think that there should be a design and discussion of the json schema. This was already a discussion topic in the previous PR that attempted to implement JSON support. Since this is going to be a sort of API, I want to get it right the first time. In particular what comes to mind:

We might want to differentiate between output lines that contain summaries and those that contain details.
The output should be readable but as compact as possible (this is probably already fine)

Can you create maybe a (separate) PR with a markdown file that explains the JSON format? We can then discuss there.

gsnw-sebast · 2025-02-15T07:15:26Z

Thanks a lot for this!

Before we merge and before further work on the implementation is done, I think that there should be a design and discussion of the json schema. This was already a discussion topic in the previous PR that attempted to implement JSON support. Since this is going to be a sort of API, I want to get it right the first time. In particular what comes to mind:
1. We might want to differentiate between output lines that contain summaries and those that contain details.

2. The output should be readable but as compact as possible (this is probably already fine)
Can you create maybe a (separate) PR with a markdown file that explains the JSON format? We can then discuss there.

I have created a discussion #381

…_system_stats() and print_global_stats()

auerswal · 2025-04-06T13:09:40Z

src/json.c

+#include <string.h>
+
+char* json_int_to_string(int input) {
+    char *result = (char *)malloc(12 * sizeof(char));


I do not see any free() for this, is this a memory leak?

That is correct. In this case, a temporary variable would have to be used in fping.c, which then releases the memory again.

char *tmp = json_int_to_string(h->num_sent); print_json_keyvalue("xmt", tmp, 0, 6); free(tmp);

I will probably remove/change the function

auerswal · 2025-04-06T13:12:50Z

src/json.c

+        return;
+    }
+
+    strcpy(safe_key, json_key);


Could you explain why you copy the string? Could you not just give json_key to fprintf()?

auerswal · 2025-04-06T13:14:17Z

src/json.c

+        fprintf(stderr, " ");
+    }
+
+    fprintf(stderr, "\"%s\": \"%s\"", safe_key, safe_value);


Could you not just use json_key and json_value instead of copying them into temporary buffers and giving those to fprintf()?

auerswal · 2025-04-06T13:19:13Z

I'd prefer JSON output from fping to be compact, i.e., not nicely formatted and indented. It should be primarily for programmatic consumption. This should allow to write simpler code for JSON output. (jq can be used to create nicely formatted JSON.)

gsnw-sebast · 2025-04-12T08:32:09Z

Due to the discussion and the resulting outcome, I made a new version.
I have discarded the previous idea with a separate json.c for security reasons.

Thanks again to @JoshIPT and @auerswal for the input

In the new version, I have simplified the duplication of the corresponding functions.

gsnw-sebast mentioned this pull request Feb 9, 2025

It would be cool if fping could return json with results #164

Closed

AthenaNetworks mentioned this pull request Feb 12, 2025

Issue/164-alternate - JSON functionality #380

Closed

gsnw-sebast force-pushed the issue/164 branch from bde460c to 7523994 Compare February 16, 2025 10:25

New option -j / --json for the JSON output in the functions print_per…

c60f59d

…_system_stats() and print_global_stats()

gsnw-sebast force-pushed the issue/164 branch from 7523994 to c60f59d Compare March 8, 2025 17:55

auerswal reviewed Apr 6, 2025

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gsnw-sebast closed this Apr 12, 2025

gsnw-sebast mentioned this pull request Apr 12, 2025

New option -J / --json for the JSON output #386

Merged

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fping --json -C 10 -p 1000 -t 2000 -q 8.8.8.8 1.1.1.1

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