Ping gets stuck completely if joining the group fails

[link2xt]

There is a server https://sombras.chat/ that does not really have federation working. Messages from sombras.chat to ci-chatmail.testrun.org are mostly not delivered (but it seems I got at least one message through recently) and messages from ci-chatmail.testrun.org arrive but with reordering.

With cmping from commit 63d8b16 I tried to run it between sombras.chat and ci-chatmail.testrun.org, it got stuck but I did not save the output. I tried to run it again now, first with nine.testrun.org it worked once and then with ci-chatmail.testrun.org it got stuck on another run:

$ cmping sombras.chat nine.testrun.org
# using accounts_dir for sombras.chat at: /home/user/.cache/cmping/sombras.chat
# using accounts_dir for nine.testrun.org at: /home/user/.cache/cmping/nine.testrun.org
# Setting up profiles... Done!
# Waiting for profiles to be online... Done!
# Waiting for receivers to come online 1/1 - Complete!
CMPING sombras.chat(mm88vn9ef@sombras.chat) -> nine.testrun.org(group with 1 receivers) count=30 interval=1.1s
64 bytes ME -> sombras.chat -> nine.testrun.org -> ME seq=0 time=3928.63ms 1/1 (elapsed: 0.00ms)
64 bytes ME -> sombras.chat -> nine.testrun.org -> ME seq=1 time=3624.49ms 1/1 (elapsed: 0.00ms)
64 bytes ME -> sombras.chat -> nine.testrun.org -> ME seq=2 time=4339.77ms 1/1 (elapsed: 0.00ms)
64 bytes ME -> sombras.chat -> nine.testrun.org -> ME seq=3 time=4173.34ms 1/1 (elapsed: 0.00ms)
--- mm88vn9ef@sombras.chat -> 1 receivers statistics ---
30 transmitted, 4 received, 86.67% loss
rtt min/avg/max/mdev = 3624.494/4016.559/4339.770/311.177 ms
--- timing statistics ---
account setup: 6.83s
group join: 5.95s
message send/recv: 93.23s
send rate: 0.32 msg/s
recv rate: 0.04 msg/s
$ cmping sombras.chat ci-chatmail.testrun.org
# using accounts_dir for sombras.chat at: /home/user/.cache/cmping/sombras.chat
# using accounts_dir for ci-chatmail.testrun.org at: /home/user/.cache/cmping/ci-chatmail.testrun.org
# Setting up profiles... Done!
# Waiting for profiles to be online... Done!
# Waiting for receivers to come online 0/1 - Complete!
# WARNING: Only 0/1 receivers joined the group
CMPING sombras.chat(mm88vn9ef@sombras.chat) -> ci-chatmail.testrun.org(group with 1 receivers) count=30 interval=1.1s
--- mm88vn9ef@sombras.chat -> 1 receivers statistics ---
30 transmitted, 0 received, 100.00% loss
--- timing statistics ---
account setup: 3.03s
group join: 31.06s
message send/recv: 93.27s
send rate: 0.32 msg/s

One problem is that cmping is creating a group in the first place, this already relies on having two-way communication somehow working. But then when it does not work, you get WARNING: Only 0/1 receivers joined the group and yet cmping continues, reports 100% loss and never finishes. The loss may even be not 100%, just the securejoin message failed and then incorrect statistics is reported.

[link2xt]

It seems there is an attempt #13 at fixing this, but I'm rather going to remove this "joining" completely. There is no need to have it as a separate step, sender can just create a group and send messages there and if some receiver misses the first N messages, it is ok, no need to wait for it.