Megalodon: manage ARK servers over RCON from a web dashboard

Watches any number of ARK:SE servers (RCON for players and chat, the query
port for map, version and player cap), records joins, leaves, chat and an
audit trail, and keeps a player database across servers.

Control: save, broadcast, chat, whisper, kick, time of day, MOTD, wild dino
wipe, a raw console with history and macros, restarts with timed warnings and
a world save, optional start command and auto-start. Bans are kept by
Megalodon: timed, cluster-wide and re-enforced when the player returns.

Automation: schedules (every N or at times of day), Discord/ntfy/webhook
notifications, welcome message, chat word filter.

Access: viewer, moderator and admin roles, API tokens, Prometheus metrics.
cmd/fakeark simulates a server for trying it out.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/ark/ark.go

@@ -0,0 +1,198 @@
+// Package ark knows the text ARK: Survival Evolved's admin console speaks: the commands to send,
+// and how to read what comes back from ListPlayers and GetChat.
+package ark
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// NoResponse is what the server answers to a command that has nothing to say.
+const NoResponse = "Server received, But no response!!"
+
+// Player is one person connected to a server.
+type Player struct {
+	Name    string `json:"name"`
+	SteamID string `json:"steam_id"`
+}
+
+var playerLine = regexp.MustCompile(`^\s*\d+\.\s+(.*),\s*(\d{15,20})\s*$`)
+
+// ParsePlayers reads the reply to ListPlayers: "0. Name, 76561198000000000" per line. Names may
+// contain commas, so the Steam ID is taken from the end of the line.
+func ParsePlayers(s string) []Player {
+	var out []Player
+	for _, line := range strings.Split(s, "\n") {
+		if m := playerLine.FindStringSubmatch(strings.TrimRight(line, "\r\x00 ")); m != nil {
+			out = append(out, Player{Name: strings.TrimSpace(m[1]), SteamID: m[2]})
+		}
+	}
+	return out
+}
+
+// ChatLine is one line from GetChat.
+type ChatLine struct {
+	Sender    string `json:"sender"`
+	Character string `json:"character,omitempty"`
+	Message   string `json:"message"`
+	Server    bool   `json:"server"` // the server itself speaking (broadcasts, admin messages)
+}
+
+var timestamp = regexp.MustCompile(`^\[\d{4}\.\d\d\.\d\d[-_]\d\d\.\d\d\.\d\d\]\s*`)
+
+// ParseChat reads the reply to GetChat. Player lines look like "Steam Name (Character): hello".
+func ParseChat(s string) []ChatLine {
+	var out []ChatLine
+	for _, line := range strings.Split(s, "\n") {
+		line = strings.TrimSpace(strings.Trim(line, "\x00"))
+		line = timestamp.ReplaceAllString(line, "")
+		if line == "" || strings.HasPrefix(line, NoResponse) {
+			continue
+		}
+		cl := ChatLine{Message: line, Server: true}
+		if i := strings.Index(line, ": "); i > 0 {
+			who := line[:i]
+			cl.Message = line[i+2:]
+			cl.Sender = who
+			if j := strings.LastIndex(who, " ("); j > 0 && strings.HasSuffix(who, ")") {
+				cl.Sender = who[:j]
+				cl.Character = who[j+2 : len(who)-1]
+			}
+			cl.Server = cl.Sender == "SERVER"
+		}
+		out = append(out, cl)
+	}
+	return out
+}
+
+// IsEmptyReply reports whether a reply carries nothing worth showing.
+func IsEmptyReply(s string) bool {
+	s = strings.TrimSpace(s)
+	return s == "" || strings.HasPrefix(s, NoResponse)
+}
+
+// ValidSteamID says whether s is a 64-bit Steam ID: digits only, so it can never smuggle anything
+// else into a command.
+func ValidSteamID(s string) bool {
+	if len(s) < 15 || len(s) > 20 {
+		return false
+	}
+	for _, r := range s {
+		if r < '0' || r > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+// Clean makes text safe to put in a command: one line, no control characters, no double quotes.
+func Clean(s string) string {
+	var sb strings.Builder
+	for _, r := range s {
+		switch {
+		case r == '"':
+			sb.WriteRune('\'')
+		case r == '\n' || r == '\r' || r == '\t':
+			sb.WriteRune(' ')
+		case r < 0x20 || r == 0x7f:
+		default:
+			sb.WriteRune(r)
+		}
+	}
+	out := strings.TrimSpace(sb.String())
+	if r := []rune(out); len(r) > 400 {
+		out = string(r[:400])
+	}
+	return out
+}
+
+// Command lines with fixed text.
+const (
+	ListPlayers      = "ListPlayers"
+	GetChat          = "GetChat"
+	SaveWorld        = "SaveWorld"
+	DoExit           = "DoExit"
+	DestroyWildDinos = "DestroyWildDinos"
+)
+
+// Broadcast shows a message in the middle of every player's screen.
+func Broadcast(msg string) (string, error) { return withText("Broadcast", msg) }
+
+// ServerChat posts a line to global chat as SERVER.
+func ServerChat(msg string) (string, error) { return withText("ServerChat", msg) }
+
+// SetMOTD changes the message of the day.
+func SetMOTD(msg string) (string, error) { return withText("SetMessageOfTheDay", msg) }
+
+func withText(cmd, msg string) (string, error) {
+	msg = Clean(msg)
+	if msg == "" {
+		return "", errors.New("the message is empty")
+	}
+	return cmd + " " + msg, nil
+}
+
+// ServerChatTo whispers a message to one player.
+func ServerChatTo(steamID, msg string) (string, error) {
+	if !ValidSteamID(steamID) {
+		return "", errors.New("not a Steam ID")
+	}
+	msg = Clean(msg)
+	if msg == "" {
+		return "", errors.New("the message is empty")
+	}
+	return fmt.Sprintf(`ServerChatTo "%s" %s`, steamID, msg), nil
+}
+
+// ForPlayer builds a command that takes only a Steam ID: KickPlayer, BanPlayer, UnbanPlayer,
+// AllowPlayerToJoinNoCheck, DisallowPlayerToJoinNoCheck.
+func ForPlayer(cmd, steamID string) (string, error) {
+	if !ValidSteamID(steamID) {
+		return "", errors.New("not a Steam ID")
+	}
+	return cmd + " " + steamID, nil
+}
+
+var timeOfDay = regexp.MustCompile(`^([01]?\d|2[0-3]):[0-5]\d(:[0-5]\d)?$`)
+
+// SetTimeOfDay sets the in-game clock to HH:MM or HH:MM:SS.
+func SetTimeOfDay(t string) (string, error) {
+	t = strings.TrimSpace(t)
+	if !timeOfDay.MatchString(t) {
+		return "", errors.New("time must look like 06:30")
+	}
+	if strings.Count(t, ":") == 1 {
+		t += ":00"
+	}
+	return "SetTimeOfDay " + t, nil
+}
+
+// Reference lists the console commands worth offering as suggestions in a UI.
+var Reference = []string{
+	"ListPlayers", "GetChat", "SaveWorld", "DoExit", "Broadcast ", "ServerChat ", `ServerChatTo "<steamid>" `,
+	`ServerChatToPlayer "<name>" `, "KickPlayer <steamid>", "BanPlayer <steamid>", "UnbanPlayer <steamid>",
+	"AllowPlayerToJoinNoCheck <steamid>", "DisallowPlayerToJoinNoCheck <steamid>", "DestroyWildDinos",
+	"SetTimeOfDay 12:00", "SetMessageOfTheDay ", "ShowMessageOfTheDay", "GiveItemToPlayer <playerid> <blueprint> 1 0 0",
+	"GiveExpToPlayer <playerid> 1000 0 0", "RenamePlayer \"<old>\" <new>", "RenameTribe \"<old>\" <new>",
+}
+
+// Duration formats d the way a player would say it ("10 minutes", "30 seconds").
+func Duration(d time.Duration) string {
+	d = d.Round(time.Second)
+	switch {
+	case d >= 2*time.Hour:
+		return fmt.Sprintf("%d hours", int(d.Hours()))
+	case d >= time.Hour:
+		return "1 hour"
+	case d >= 2*time.Minute:
+		return fmt.Sprintf("%d minutes", int(d.Minutes()))
+	case d >= time.Minute:
+		return "1 minute"
+	case d == time.Second:
+		return "1 second"
+	}
+	return fmt.Sprintf("%d seconds", int(d.Seconds()))
+}