Integers not being displayed properly for 'sender_has_retransmits' and possibly other items.

[WatcherOfTheSkies]

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Context

Testing with debug enabled.

• Version of iperf3:
  V3.12

• Hardware:
  Custom ARM based RF board as the server and a Raspberry Pi as the client

• Operating system (and distribution, if any):
  Linux

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Support may be provided on a best-effort basis to other UNIX-like
platforms. We cannot provide support for building and/or running
iperf3 on Windows, iOS, or Android.

• Other relevant information (for example, non-default compilers,
  libraries, cross-compiling, etc.):

Please fill out one of the "Bug Report" or "Enhancement Request"
sections, as appropriate. Note that submissions of bug fixes, new
features, etc. should be done as a pull request at
https://github.com/esnet/iperf/pulls

Bug Report

The code snippet is from iperf_api.c

if ( test->mode == RECEIVER )
  sender_has_retransmits = -1;
else
  sender_has_retransmits = test->sender_has_retransmits;

cJSON_AddNumberToObject(j, "sender_has_retransmits", sender_has_retransmits);

The item sender_has_retransmits is an int, However, it's reported in Json via cJSON_AddNumberToObject. This function takes a double as the value. Consequently, -1 gets displayed as 18446744073709551615

• Expected Behavior

"retransmits": -1,
or
"retransmits": <ANY_INT_VALUE>,

• Actual Behavior
  send_results
  {
  "cpu_util_total": 0.21799147343840383,
  "cpu_util_user": 0,
  "cpu_util_system": 0.21797719109067146,
  "sender_has_retransmits": 18446744073709551615,
  "congestion_used": "cubic",
  "streams": [{
  "id": 1,
  "bytes": 0,
  "retransmits": 18446744073709551615,
  "jitter": 0,
  "errors": 0,
  "packets": 0,
  "start_time": 0,
  "end_time": 5.000827
  }]
  }

• Steps to Reproduce
  Server: iperf3 --server -1 -p 5201 --verbose
  Client: iperf3 --client 192.168.200.242 --port 5201 --bind 10.0.0.2%wwan0 --time 5 --verbose --reverse -d

This was spotted when the -d option was used.

• Possible Solution

Perhaps a function with...
cJSON_AddDoubleToObject
cJSON_AddIntToObject

Enhancement Request

• Current behavior

• Desired behavior

• Implementation notes

[WatcherOfTheSkies]

The use case is very specific but the reporting will be generic. I'm surprised this hasn't been seen more often.

[WatcherOfTheSkies]

Would it be better if variables like sender_has_retransmits were initialised to 0 instead? Then if there were no retransmits, at least it would display 0. I'm not sure at this time if there are any further side effects by doing this.

[davidBar-On]

The "sender_has_retransmits" and "retransmits" related variables values are -1 as required. The problem is only in the printing of these values, as numbers from struct cJSON are printed as unsigned numbers. Probably this was not detected before since this is a debug message and there are no other cases of printing negative values from the JSON structure.

Submitted a PR #1539 with a fix.

[WatcherOfTheSkies]

Excellent! I'm glad that there is a better solution.
Thank You.