Trying a UDP request with binary body but CONNECTED is always false

[Exagone313]

Hello,

My Gatus version is v5.23.2.

I'm trying to monitor an Enemy Territory server using a UDP endpoint with a body.

For this to work, it needs to send a query that starts with non-ascii characters (four 255 bytes).

I tried with this:

endpoints:
- name: etbloat
  url: "udp://etbloat.ewd.app:27960"
  group: "🎮 Game Server"
  interval: 5m
  conditions:
  - "[CONNECTED] == true"
  body: "\xFF\xFF\xFF\xFFgetstatus"
  alerts:
  - type: discord

and this:

endpoints:
- name: etbloat
  url: "udp://etbloat.ewd.app:27960"
  group: "🎮 Game Server"
  interval: 5m
  conditions:
  - "[CONNECTED] == true"
  body: "����getstatus"
  alerts:
  - type: discord

but CONNECTED is false in either case.

(From my understanding, both forms are valid in YAML.)

This shell command works as expected:

echo -n -e "\xff\xff\xff\xffgetstatus" | timeout 1.2 nc -u -w 1 etbloat.ewd.app 27960

Show response

����statusResponse
\mod_wolfadmin\1.2.1\g_doubleJumpHeight\1.4\mod_url\etblo.at\mod_version\etbloat-b2f31d5c\omnibot_playing\30\P\--121212121212121212121212121212\g_axismaxlives\0\g_alliedmaxlives\0\voteFlags\916635\g_balancedteams\1\gamename\etbloat\g_doubleJump\2\g_soldierChargeTime\15000\g_medicChargeTime\15000\g_fieldopsChargeTime\15000\g_engineerChargeTime\15000\g_covertopsChargeTime\15000\g_voteFlags\0\g_minGameClients\8\g_needpass\0\sv_maxPing\0\sv_minPing\0\sv_dlRate\100\sv_maxRate\0\sv_minRate\0\mapname\rommel_ga\protocol\84\g_heavyWeaponRestriction\100\g_maxlivesRespawnPenalty\0\g_maxGameClients\0\g_dynamiteCounter\25\timelimit\15\g_antilag\1\g_maxlives\0\g_friendlyFire\0\sv_hostname\^2etblo^1.^2at ^5test ^2server\g_redLimboTime\8000\g_blueLimboTime\8000\g_gametype\2\sv_privateclients\2\sv_maxclients\60\g_oss\327\version\ET Legacy v2.83.2 linux-x86_64 Jan 19 2025
203 0 "^o[BOT]^7Halfwit"
132 0 "^o[BOT]^7Morgriff"
64 0 "^o[BOT]^7Aimless"
127 0 "^o[BOT]^7Merki"
101 0 "^o[BOT]^7Fullmonty"
74 0 "^o[BOT]

For the record, the bytes sent are:

$ echo -n -e "\xff\xff\xff\xffgetstatus" | hexyl                                       
┌────────┬─────────────────────────┬─────────────────────────┬────────┬────────┐
│00000000│ ff ff ff ff 67 65 74 73 ┊ 74 61 74 75 73          │××××gets┊tatus   │
└────────┴─────────────────────────┴─────────────────────────┴────────┴────────┘

Any idea why it is not working?

PS: Feel free to (fairly) send requests to the server, I do not mind.

[Exagone313]

In fact it doesn't send the right bytes. I used a netcat server and here is what it received:

# echo -n -e "\xff\xff\xff\xffstatusResponse\ntest" | nc -u -l -p 27960 | hexdump -v -e '1/1 "%02x\n"'
ef
bf
bd
ef
bf
bd
ef
bf
bd
ef
bf
bd
67
65
74
73
74
61
74
75
73

It starts with 0xEF 0xBF 0xBD 0xEF 0xBF 0xBD 0xEF 0xBF 0xBD 0xEF 0xBF 0xBD instead of 0xFF 0xFF 0xFF 0xFF.

(In this case, CONNECTED is true as my server sent a response, so it's all a matter of sending the right packet in the first place. The Enemy Territory server doesn't answer to malformed packets.)

For the record:

# echo -n -e "\xff\xff\xff\xffgetstatus" | hexdump -v -e '1/1 "%02x\n"'
ff
ff
ff
ff
67
65
74
73
74
61
74
75
73

The code only supports UTF-8 strings as body. I would need support for byte-typed body.

[Exagone313]

Opened issue #1265

[TwiN]

Good catch.