Mixed big-endian and little-endian UDP test fails

[mriswyth]

• Version of iperf3: 3.12

• Hardware: x86_64 and MIPS 74Kc V5.0

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

Bug Report

Mixing a big-endian and little-endian systems for the client and server results in UDP tests failing to start.

This is the failed output of an x86_64 PC client command running against a big-endian server

perf3 -c FE80::848D:84FF:FEFE:9165%eno1 -n 1 -u --debug --verbose
iperf 3.12
Linux bthompson.rajant.com 6.0.5-200.fc36.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Oct 26 15:55:21 UTC 2022 x86_64
Control connection MSS 1428
Setting UDP block size to 1428
send_parameters:
{
        "udp":  true,
        "omit": 0,
        "time": 0,
        "num":  1,
        "blockcount":   0,
        "parallel":     1,
        "len":  1428,
        "bandwidth":    1048576,
        "pacing_timer": 1000,
        "client_version":       "3.12"
}
Time: Fri, 04 Nov 2022 17:42:46 UTC
Connecting to host FE80::848D:84FF:FEFE:9165%eno1, port 5201
      Cookie: oc7rjz2iw7yvlmrsxv2gpswowhlcamlqjdna
      Target Bitrate: 1048576
SNDBUF is 212992, expecting 0
RCVBUF is 212992, expecting 0
Setting application pacing to 131072
Sending Connect message to Socket 5
Connect received for Socket 5, sz=4, buf=36373839, i=0, max_len_wait_for_reply=4
iperf3: error - unable to read from stream socket: Invalid argument

This is the output of the same client running against a little-endian server

iperf3 -c FE80::D0:12FF:FE28:F3BD%eno1 -n 1 -u --debug --verbose
iperf 3.12
Linux bthompson.rajant.com 6.0.5-200.fc36.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Oct 26 15:55:21 UTC 2022 x86_64
Control connection MSS 1428
Setting UDP block size to 1428
send_parameters:
{
        "udp":  true,
        "omit": 0,
        "time": 0,
        "num":  1,
        "blockcount":   0,
        "parallel":     1,
        "len":  1428,
        "bandwidth":    1048576,
        "pacing_timer": 1000,
        "client_version":       "3.12"
}
Time: Fri, 04 Nov 2022 17:45:06 UTC
Connecting to host FE80::D0:12FF:FE28:F3BD%eno1, port 5201
      Cookie: fqqbhjoeafb2lt355cvfsphpagt6nfeufoev
      Target Bitrate: 1048576
SNDBUF is 212992, expecting 0
RCVBUF is 212992, expecting 0
Setting application pacing to 131072
Sending Connect message to Socket 5
Connect received for Socket 5, sz=4, buf=39383736, i=0, max_len_wait_for_reply=4
[  5] local fe80::bf96:250b:5c8e:66f9 port 59907 connected to fe80::d0:12ff:fe28:f3bd port 5201
Starting Test: protocol: UDP, 1 streams, 1428 byte blocks, omitting 0 seconds, 1 bytes to send, tos 0
sent 1428 bytes of 1428, total 1428
send_results
{
        "cpu_util_total":       22.401289282836423,
        "cpu_util_user":        22.401289282836423,
        "cpu_util_system":      0,
        "sender_has_retransmits":       0,
        "streams":      [{
                        "id":   1,
                        "bytes":        1428,
                        "retransmits":  18446744073709551615,
                        "jitter":       0,
                        "errors":       0,
                        "packets":      1,
                        "start_time":   0,
                        "end_time":     0.000109
                }]
}
get_results
{
        "cpu_util_total":       26.626425217974514,
        "cpu_util_user":        0,
        "cpu_util_system":      26.626425217974514,
        "sender_has_retransmits":       1.8446744073709552e+19,
        "streams":      [{
                        "id":   1,
                        "bytes":        0,
                        "retransmits":  1.8446744073709552e+19,
                        "jitter":       0,
                        "errors":       0,
                        "packets":      0,
                        "start_time":   0,
                        "end_time":     0.001297
                }]
}
interval_len 0.000109 bytes_transferred 1428
interval forces keep
[ ID] Interval           Transfer     Bitrate         Total Datagrams
[  5]   0.00-0.00   sec  1.39 KBytes   105 Mbits/sec  1  
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Jitter    Lost/Total Datagrams
[  5]   0.00-0.00   sec  1.39 KBytes   105 Mbits/sec  0.000 ms  0/1 (0%)  sender
[  5]   0.00-0.00   sec  0.00 Bytes  0.00 bits/sec  0.000 ms  0/0 (0%)  receiver
CPU Utilization: local/sender 22.4% (22.4%u/0.0%s), remote/receiver 26.6% (0.0%u/26.6%s)

iperf Done.

• Expected Behavior
  UDP test runs successfully.

• Actual Behavior
  UDP test fails to run.

• Steps to Reproduce
  iperf3 -c <other-endian system> -u

• Possible Solution
  Have the UDP client connection recognize either value as a response message.

[bmah888]

Fixed with PR #1468.