A few gaming features added, e.g. rolling dice, flipping coin, eightball.

rtpconn/coin.go

@@ -0,0 +1,50 @@
+package rtpconn
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io"
+	"math/big"
+	"strings"
+
+	"git.stormux.org/storm/skald/hall"
+)
+
+var coinSides = []string{"heads", "tails"}
+
+func chooseCoinSide(reader io.Reader) (string, error) {
+	index, err := rand.Int(reader, big.NewInt(int64(len(coinSides))))
+	if err != nil {
+		return "", err
+	}
+	return coinSides[index.Int64()], nil
+}
+
+func validateCoinRequest(value any) error {
+	if value == nil {
+		return nil
+	}
+	arguments, ok := value.(string)
+	if !ok || strings.TrimSpace(arguments) != "" {
+		return hall.UserError("/coin does not take any arguments")
+	}
+	return nil
+}
+
+func handleCoinFlip(c *webClient, g *hall.Hall, value any) error {
+	if !member("message", c.Permissions()) {
+		return c.error(hall.UserError("not authorised"))
+	}
+	if err := validateCoinRequest(value); err != nil {
+		return c.error(err)
+	}
+	side, err := chooseCoinSide(rand.Reader)
+	if err != nil {
+		return c.error(err)
+	}
+	announcement := fmt.Sprintf("%s flips a coin: %s.", c.Username(), side)
+	if err := broadcastServerChat(g, "Coin", "coin", announcement); err != nil {
+		return c.error(err)
+	}
+	return nil
+}

rtpconn/coin_test.go

@@ -0,0 +1,90 @@
+package rtpconn
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestChooseCoinSide(t *testing.T) {
+	for i, want := range []string{"heads", "tails"} {
+		got, err := chooseCoinSide(bytes.NewReader([]byte{byte(i)}))
+		if err != nil {
+			t.Fatalf("chooseCoinSide(%d): %v", i, err)
+		}
+		if got != want {
+			t.Fatalf("chooseCoinSide(%d) = %q, want %q", i, got, want)
+		}
+	}
+}
+
+func TestCoinRejectsArguments(t *testing.T) {
+	for _, value := range []any{nil, "", "   "} {
+		if err := validateCoinRequest(value); err != nil {
+			t.Fatalf("validateCoinRequest(%#v): %v", value, err)
+		}
+	}
+	for _, value := range []any{"twice", 2} {
+		if err := validateCoinRequest(value); err == nil {
+			t.Fatalf("validateCoinRequest(%#v) unexpectedly succeeded", value)
+		}
+	}
+}
+
+func TestCoinFlipIsServerGeneratedAndStoredInHistory(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	flipper := addTestWebClient(t, hallName, "Participant", "message")
+	observer := addTestWebClient(t, hallName, "Operator", "op")
+
+	if err := handleClientMessage(flipper, clientMessage{
+		Type: "hallaction", Kind: "coin", Value: "",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(coin): %v", err)
+	}
+
+	for name, messages := range map[string][]clientMessage{
+		"flipper":  drainMessages(flipper),
+		"observer": drainMessages(observer),
+	} {
+		if len(messages) != 1 {
+			t.Fatalf("%s received %d messages, want 1: %#v", name, len(messages), messages)
+		}
+		message := messages[0]
+		if message.Type != "chat" || message.Kind != "coin" || !message.Privileged {
+			t.Fatalf("%s received non-authoritative coin message: %#v", name, message)
+		}
+		if message.Source != "" || message.Username == nil || *message.Username != "Coin" {
+			t.Fatalf("%s received coin message with unexpected identity: %#v", name, message)
+		}
+		text, ok := message.Value.(string)
+		if !ok || (text != "Participant flips a coin: heads." &&
+			text != "Participant flips a coin: tails.") {
+			t.Fatalf("%s received malformed coin announcement %q", name, text)
+		}
+	}
+
+	history := flipper.hall.GetChatHistory()
+	if len(history) != 1 || history[0].Kind != "coin" {
+		t.Fatalf("coin history = %#v", history)
+	}
+}
+
+func TestCoinFlipRequiresMessagePermission(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	flipper := addTestWebClient(t, hallName, "Participant", "message")
+	flipper.permissions = remove("message", flipper.permissions)
+
+	if err := handleClientMessage(flipper, clientMessage{
+		Type: "hallaction", Kind: "coin", Value: "",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(coin): %v", err)
+	}
+	if got := flipper.hall.GetChatHistory(); len(got) != 0 {
+		t.Fatalf("unauthorised coin flip entered history: %#v", got)
+	}
+	messages := drainMessages(flipper)
+	if len(messages) != 1 || messages[0].Kind != "error" ||
+		!strings.Contains(messages[0].Value.(string), "not authorised") {
+		t.Fatalf("unauthorised coin response = %#v", messages)
+	}
+}

rtpconn/dice.go

@@ -0,0 +1,147 @@
+package rtpconn
+
+import (
+	"crypto/rand"
+	"fmt"
+	"math/big"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"git.stormux.org/storm/skald/hall"
+)
+
+const (
+	maxDiceCount    = 100
+	maxDiceSides    = 1_000_000
+	maxDiceModifier = 1_000_000
+	dicePreviewSize = 5
+)
+
+var diceExpressionRegexp = regexp.MustCompile(
+	`^\s*([0-9]+)\s*[dD]\s*([0-9]+)(?:\s*([+-])\s*([0-9]+))?\s*$`,
+)
+
+type diceRoll struct {
+	Count    int64
+	Sides    int64
+	Modifier int64
+	Results  []int64
+	Total    int64
+}
+
+func parseDiceExpression(expression string) (diceRoll, error) {
+	match := diceExpressionRegexp.FindStringSubmatch(expression)
+	if match == nil {
+		return diceRoll{}, hall.UserError(
+			"invalid dice roll; example: /2d6 + 3",
+		)
+	}
+
+	count, err := strconv.ParseInt(match[1], 10, 64)
+	if err != nil || count < 1 || count > maxDiceCount {
+		return diceRoll{}, hall.UserError(
+			fmt.Sprintf("dice count must be between 1 and %d", maxDiceCount),
+		)
+	}
+	sides, err := strconv.ParseInt(match[2], 10, 64)
+	if err != nil || sides < 2 || sides > maxDiceSides {
+		return diceRoll{}, hall.UserError(
+			fmt.Sprintf("die sides must be between 2 and %d", maxDiceSides),
+		)
+	}
+
+	var modifier int64
+	if match[4] != "" {
+		modifier, err = strconv.ParseInt(match[4], 10, 64)
+		if err != nil || modifier > maxDiceModifier {
+			return diceRoll{}, hall.UserError(
+				fmt.Sprintf("dice modifier must be between -%d and %d", maxDiceModifier, maxDiceModifier),
+			)
+		}
+		if match[3] == "-" {
+			modifier = -modifier
+		}
+	}
+
+	return diceRoll{Count: count, Sides: sides, Modifier: modifier}, nil
+}
+
+func generateDiceRoll(roll diceRoll) (diceRoll, error) {
+	maximum := big.NewInt(roll.Sides)
+	roll.Results = make([]int64, roll.Count)
+	roll.Total = roll.Modifier
+	for i := range roll.Results {
+		result, err := rand.Int(rand.Reader, maximum)
+		if err != nil {
+			return diceRoll{}, err
+		}
+		roll.Results[i] = result.Int64() + 1
+		roll.Total += roll.Results[i]
+	}
+	return roll, nil
+}
+
+func formatDiceResults(results []int64) string {
+	shown := len(results)
+	if shown > dicePreviewSize {
+		shown = dicePreviewSize
+	}
+	parts := make([]string, shown)
+	for i := range parts {
+		parts[i] = strconv.FormatInt(results[i], 10)
+	}
+
+	if len(results) > dicePreviewSize {
+		return strings.Join(parts, ", ") + fmt.Sprintf(", and %d more", len(results)-shown)
+	}
+	if shown == 1 {
+		return parts[0]
+	}
+	if shown == 2 {
+		return parts[0] + " and " + parts[1]
+	}
+	return strings.Join(parts[:shown-1], ", ") + ", and " + parts[shown-1]
+}
+
+func formatDiceAnnouncement(username string, roll diceRoll) string {
+	dieWord := "dice"
+	if roll.Count == 1 {
+		dieWord = "die"
+	}
+	modifier := ""
+	if roll.Modifier > 0 {
+		modifier = fmt.Sprintf(", plus %d", roll.Modifier)
+	} else if roll.Modifier < 0 {
+		modifier = fmt.Sprintf(", minus %d", -roll.Modifier)
+	}
+	return fmt.Sprintf(
+		"%s rolls %d %d-sided %s: %s%s, for a total of %d.",
+		username, roll.Count, roll.Sides, dieWord,
+		formatDiceResults(roll.Results), modifier, roll.Total,
+	)
+}
+
+func handleDiceRoll(c *webClient, g *hall.Hall, value any) error {
+	if !member("message", c.Permissions()) {
+		return c.error(hall.UserError("not authorised"))
+	}
+	expression, ok := value.(string)
+	if !ok {
+		return c.error(hall.UserError("invalid dice roll; example: /2d6 + 3"))
+	}
+	roll, err := parseDiceExpression(expression)
+	if err != nil {
+		return c.error(err)
+	}
+	roll, err = generateDiceRoll(roll)
+	if err != nil {
+		return c.error(err)
+	}
+
+	announcement := formatDiceAnnouncement(c.Username(), roll)
+	if err := broadcastServerChat(g, "Dice", "dice", announcement); err != nil {
+		return c.error(err)
+	}
+	return nil
+}

rtpconn/dice_test.go

@@ -0,0 +1,223 @@
+package rtpconn
+
+import (
+	"regexp"
+	"strings"
+	"testing"
+
+	"git.stormux.org/storm/skald/hall"
+)
+
+func TestParseDiceExpression(t *testing.T) {
+	tests := []struct {
+		expression string
+		count      int64
+		sides      int64
+		modifier   int64
+	}{
+		{"2d4", 2, 4, 0},
+		{"10d8 + 5", 10, 8, 5},
+		{"3 d 2+5", 3, 2, 5},
+		{"2 D 20 - 1", 2, 20, -1},
+		{" 1d6 ", 1, 6, 0},
+	}
+
+	for _, test := range tests {
+		t.Run(test.expression, func(t *testing.T) {
+			got, err := parseDiceExpression(test.expression)
+			if err != nil {
+				t.Fatalf("parseDiceExpression(%q): %v", test.expression, err)
+			}
+			if got.Count != test.count || got.Sides != test.sides || got.Modifier != test.modifier {
+				t.Fatalf("parseDiceExpression(%q) = %#v", test.expression, got)
+			}
+		})
+	}
+}
+
+func TestParseDiceExpressionRejectsInvalidAndOversizedRolls(t *testing.T) {
+	tests := []string{
+		"", "d20", "2d", "2d1", "0d6", "101d6", "2d1000001",
+		"2d6 + 1000001", "2 0d6", "2d6 trailing",
+	}
+	for _, expression := range tests {
+		t.Run(expression, func(t *testing.T) {
+			if _, err := parseDiceExpression(expression); err == nil {
+				t.Fatalf("parseDiceExpression(%q) unexpectedly succeeded", expression)
+			}
+		})
+	}
+}
+
+func TestFormatDiceAnnouncement(t *testing.T) {
+	tests := []struct {
+		name     string
+		roll     diceRoll
+		expected string
+	}{
+		{
+			"two dice",
+			diceRoll{Count: 2, Sides: 4, Results: []int64{1, 2}, Total: 3},
+			"Storm rolls 2 4-sided dice: 1 and 2, for a total of 3.",
+		},
+		{
+			"many dice with modifier",
+			diceRoll{Count: 10, Sides: 10, Modifier: 5, Results: []int64{2, 3, 4, 3, 4, 1, 2, 1, 2, 3}, Total: 30},
+			"Storm rolls 10 10-sided dice: 2, 3, 4, 3, 4, and 5 more, plus 5, for a total of 30.",
+		},
+		{
+			"one die with negative modifier",
+			diceRoll{Count: 1, Sides: 20, Modifier: -1, Results: []int64{17}, Total: 16},
+			"Storm rolls 1 20-sided die: 17, minus 1, for a total of 16.",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := formatDiceAnnouncement("Storm", test.roll); got != test.expected {
+				t.Fatalf("formatDiceAnnouncement() = %q, want %q", got, test.expected)
+			}
+		})
+	}
+}
+
+func TestGenerateDiceRollStaysWithinBounds(t *testing.T) {
+	roll, err := generateDiceRoll(diceRoll{Count: 100, Sides: 6, Modifier: -50})
+	if err != nil {
+		t.Fatalf("generateDiceRoll: %v", err)
+	}
+	if len(roll.Results) != 100 {
+		t.Fatalf("generated %d results, want 100", len(roll.Results))
+	}
+	wantTotal := int64(-50)
+	for _, result := range roll.Results {
+		if result < 1 || result > 6 {
+			t.Fatalf("generated result %d outside 1..6", result)
+		}
+		wantTotal += result
+	}
+	if roll.Total != wantTotal {
+		t.Fatalf("total = %d, want %d", roll.Total, wantTotal)
+	}
+}
+
+func TestDiceRollIsServerGeneratedAndStoredInHistory(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	roller := addTestWebClient(t, hallName, "Participant", "message")
+	observer := addTestWebClient(t, hallName, "Operator", "op")
+
+	if err := handleClientMessage(roller, clientMessage{
+		Type:  "hallaction",
+		Kind:  "roll",
+		Value: "2d4 + 5",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(roll): %v", err)
+	}
+
+	for name, messages := range map[string][]clientMessage{
+		"roller":   drainMessages(roller),
+		"observer": drainMessages(observer),
+	} {
+		if len(messages) != 1 {
+			t.Fatalf("%s received %d messages, want 1: %#v", name, len(messages), messages)
+		}
+		message := messages[0]
+		if message.Type != "chat" || message.Kind != "dice" || !message.Privileged {
+			t.Fatalf("%s received non-authoritative dice message: %#v", name, message)
+		}
+		if message.Source != "" || message.Username == nil || *message.Username != "Dice" {
+			t.Fatalf("%s received dice message with unexpected identity: %#v", name, message)
+		}
+		text, ok := message.Value.(string)
+		if !ok || !regexp.MustCompile(`^Participant rolls 2 4-sided dice: [1-4] and [1-4], plus 5, for a total of (7|8|9|10|11|12|13)\.$`).MatchString(text) {
+			t.Fatalf("%s received malformed dice announcement %q", name, text)
+		}
+	}
+
+	history := roller.hall.GetChatHistory()
+	if len(history) != 1 || history[0].Kind != "dice" {
+		t.Fatalf("dice history = %#v", history)
+	}
+
+	newcomer := testWebClient("admin-id")
+	adminName := "Admin"
+	if _, err := hall.AddClient(hallName, newcomer, hall.ClientCredentials{
+		Username: &adminName,
+		Password: "pw",
+	}); err != nil {
+		t.Fatalf("AddClient(Admin): %v", err)
+	}
+	newcomer.hall = hall.Get(hallName)
+	drainActions(t, newcomer)
+	var historicalDice *clientMessage
+	for _, message := range drainMessages(newcomer) {
+		if message.Type == "chathistory" && message.Kind == "dice" {
+			message := message
+			historicalDice = &message
+			break
+		}
+	}
+	if historicalDice == nil || !historicalDice.Privileged {
+		t.Fatalf("new participant did not receive authoritative dice history: %#v", historicalDice)
+	}
+}
+
+func TestDiceRollRequiresMessagePermission(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	roller := addTestWebClient(t, hallName, "Participant", "message")
+	roller.permissions = remove("message", roller.permissions)
+
+	if err := handleClientMessage(roller, clientMessage{
+		Type: "hallaction", Kind: "roll", Value: "1d6",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(roll): %v", err)
+	}
+	if got := roller.hall.GetChatHistory(); len(got) != 0 {
+		t.Fatalf("unauthorised roll entered history: %#v", got)
+	}
+	messages := drainMessages(roller)
+	if len(messages) != 1 || messages[0].Kind != "error" ||
+		!strings.Contains(messages[0].Value.(string), "not authorised") {
+		t.Fatalf("unauthorised roll response = %#v", messages)
+	}
+}
+
+func TestClientsCannotSubmitServerGeneratedMessages(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	roller := addTestWebClient(t, hallName, "Participant", "message")
+
+	for _, messageKind := range []string{"dice", "eightball", "coin"} {
+		for _, messageType := range []string{"chat", "usermessage"} {
+			drainMessages(roller)
+			if err := handleClientMessage(roller, clientMessage{
+				Type: messageType, Kind: messageKind, Value: "whatever result I wanted",
+			}); err != nil {
+				t.Fatalf("handleClientMessage(%s, %s): %v", messageType, messageKind, err)
+			}
+			messages := drainMessages(roller)
+			if len(messages) != 1 || messages[0].Kind != "error" {
+				t.Fatalf("reserved %s/%s response = %#v", messageType, messageKind, messages)
+			}
+		}
+	}
+	if got := roller.hall.GetChatHistory(); len(got) != 0 {
+		t.Fatalf("forged dice message entered history: %#v", got)
+	}
+}
+
+func TestChatIdentityComesFromConnection(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	sender := addTestWebClient(t, hallName, "Participant", "message")
+	observer := addTestWebClient(t, hallName, "Operator", "op")
+
+	if err := handleClientMessage(sender, clientMessage{
+		Type: "chat", Value: "hello",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(chat): %v", err)
+	}
+	messages := drainMessages(observer)
+	if len(messages) != 1 || messages[0].Source != sender.id ||
+		messages[0].Username == nil || *messages[0].Username != "Participant" {
+		t.Fatalf("chat did not use connection identity: %#v", messages)
+	}
+}

rtpconn/eightball.go

@@ -0,0 +1,85 @@
+package rtpconn
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io"
+	"math/big"
+	"strings"
+	"unicode/utf8"
+
+	"git.stormux.org/storm/skald/hall"
+)
+
+const maxEightBallQuestionRunes = 500
+
+var eightBallResponses = []string{
+	"It is certain.",
+	"It is decidedly so.",
+	"Without a doubt.",
+	"Yes, definitely.",
+	"You may rely on it.",
+	"As I see it, yes.",
+	"Most likely.",
+	"Outlook good.",
+	"Yes.",
+	"Signs point to yes.",
+	"Reply hazy, try again.",
+	"Ask again later.",
+	"Better not tell you now.",
+	"Cannot predict now.",
+	"Concentrate and ask again.",
+	"Don't count on it.",
+	"My reply is no.",
+	"My sources say no.",
+	"Outlook not so good.",
+	"Very doubtful.",
+}
+
+func normalizeEightBallQuestion(value any) (string, error) {
+	question, ok := value.(string)
+	if !ok {
+		return "", hall.UserError("/8ball requires a question")
+	}
+	question = strings.Join(strings.Fields(question), " ")
+	if question == "" {
+		return "", hall.UserError("/8ball requires a question")
+	}
+	if utf8.RuneCountInString(question) > maxEightBallQuestionRunes {
+		return "", hall.UserError(fmt.Sprintf(
+			"Eight Ball questions may not exceed %d characters",
+			maxEightBallQuestionRunes,
+		))
+	}
+	return question, nil
+}
+
+func chooseEightBallResponse(reader io.Reader) (string, error) {
+	index, err := rand.Int(reader, big.NewInt(int64(len(eightBallResponses))))
+	if err != nil {
+		return "", err
+	}
+	return eightBallResponses[index.Int64()], nil
+}
+
+func handleEightBall(c *webClient, g *hall.Hall, value any) error {
+	if !member("message", c.Permissions()) {
+		return c.error(hall.UserError("not authorised"))
+	}
+	question, err := normalizeEightBallQuestion(value)
+	if err != nil {
+		return c.error(err)
+	}
+	response, err := chooseEightBallResponse(rand.Reader)
+	if err != nil {
+		return c.error(err)
+	}
+	announcement := fmt.Sprintf(
+		"%s asks: %s\nThe Eight Ball says: %s",
+		c.Username(), question, response,
+	)
+	if err := broadcastServerChat(g, "Eight Ball", "eightball", announcement); err != nil {
+		return c.error(err)
+	}
+	return nil
+}

rtpconn/eightball_test.go

@@ -0,0 +1,120 @@
+package rtpconn
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestEightBallHasClassicResponses(t *testing.T) {
+	want := []string{
+		"It is certain.",
+		"It is decidedly so.",
+		"Without a doubt.",
+		"Yes, definitely.",
+		"You may rely on it.",
+		"As I see it, yes.",
+		"Most likely.",
+		"Outlook good.",
+		"Yes.",
+		"Signs point to yes.",
+		"Reply hazy, try again.",
+		"Ask again later.",
+		"Better not tell you now.",
+		"Cannot predict now.",
+		"Concentrate and ask again.",
+		"Don't count on it.",
+		"My reply is no.",
+		"My sources say no.",
+		"Outlook not so good.",
+		"Very doubtful.",
+	}
+	if len(eightBallResponses) != len(want) {
+		t.Fatalf("eightBallResponses has %d entries, want %d", len(eightBallResponses), len(want))
+	}
+	for i := range want {
+		if eightBallResponses[i] != want[i] {
+			t.Fatalf("eightBallResponses[%d] = %q, want %q", i, eightBallResponses[i], want[i])
+		}
+		response, err := chooseEightBallResponse(bytes.NewReader([]byte{byte(i)}))
+		if err != nil {
+			t.Fatalf("chooseEightBallResponse(%d): %v", i, err)
+		}
+		if response != want[i] {
+			t.Fatalf("chooseEightBallResponse(%d) = %q, want %q", i, response, want[i])
+		}
+	}
+}
+
+func TestNormalizeEightBallQuestion(t *testing.T) {
+	question, err := normalizeEightBallQuestion("  Will\nwe win tonight?  ")
+	if err != nil {
+		t.Fatalf("normalizeEightBallQuestion: %v", err)
+	}
+	if question != "Will we win tonight?" {
+		t.Fatalf("question = %q", question)
+	}
+
+	for _, value := range []any{"   ", strings.Repeat("x", maxEightBallQuestionRunes+1), 42} {
+		if _, err := normalizeEightBallQuestion(value); err == nil {
+			t.Fatalf("normalizeEightBallQuestion(%#v) unexpectedly succeeded", value)
+		}
+	}
+}
+
+func TestEightBallIsServerGeneratedAndStoredInHistory(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	asker := addTestWebClient(t, hallName, "Participant", "message")
+	observer := addTestWebClient(t, hallName, "Operator", "op")
+
+	if err := handleClientMessage(asker, clientMessage{
+		Type: "hallaction", Kind: "eightball", Value: "Will we win tonight?",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(eightball): %v", err)
+	}
+
+	for name, messages := range map[string][]clientMessage{
+		"asker":    drainMessages(asker),
+		"observer": drainMessages(observer),
+	} {
+		if len(messages) != 1 {
+			t.Fatalf("%s received %d messages, want 1: %#v", name, len(messages), messages)
+		}
+		message := messages[0]
+		if message.Type != "chat" || message.Kind != "eightball" || !message.Privileged {
+			t.Fatalf("%s received non-authoritative Eight Ball message: %#v", name, message)
+		}
+		if message.Source != "" || message.Username == nil || *message.Username != "Eight Ball" {
+			t.Fatalf("%s received Eight Ball message with unexpected identity: %#v", name, message)
+		}
+		text, ok := message.Value.(string)
+		if !ok || !strings.HasPrefix(text, "Participant asks: Will we win tonight?\nThe Eight Ball says: ") {
+			t.Fatalf("%s received malformed Eight Ball announcement %q", name, text)
+		}
+	}
+
+	history := asker.hall.GetChatHistory()
+	if len(history) != 1 || history[0].Kind != "eightball" {
+		t.Fatalf("Eight Ball history = %#v", history)
+	}
+}
+
+func TestEightBallRequiresMessagePermission(t *testing.T) {
+	hallName := newChalkboardTestHall(t)
+	asker := addTestWebClient(t, hallName, "Participant", "message")
+	asker.permissions = remove("message", asker.permissions)
+
+	if err := handleClientMessage(asker, clientMessage{
+		Type: "hallaction", Kind: "eightball", Value: "Will this work?",
+	}); err != nil {
+		t.Fatalf("handleClientMessage(eightball): %v", err)
+	}
+	if got := asker.hall.GetChatHistory(); len(got) != 0 {
+		t.Fatalf("unauthorised Eight Ball question entered history: %#v", got)
+	}
+	messages := drainMessages(asker)
+	if len(messages) != 1 || messages[0].Kind != "error" ||
+		!strings.Contains(messages[0].Value.(string), "not authorised") {
+		t.Fatalf("unauthorised Eight Ball response = %#v", messages)
+	}
+}

rtpconn/serverchat.go

@@ -0,0 +1,32 @@
+package rtpconn
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"time"
+
+	"git.stormux.org/storm/skald/hall"
+)
+
+func isServerGeneratedChatKind(kind string) bool {
+	return kind == "dice" || kind == "eightball" || kind == "coin"
+}
+
+func broadcastServerChat(g *hall.Hall, name, kind, message string) error {
+	idBytes := make([]byte, 8)
+	if _, err := rand.Read(idBytes); err != nil {
+		return err
+	}
+	id := base64.RawURLEncoding.EncodeToString(idBytes)
+	now := time.Now()
+	g.AddToChatHistory(id, "", &name, now, kind, message)
+	return broadcast(g.GetClients(nil), clientMessage{
+		Type:       "chat",
+		Id:         id,
+		Username:   &name,
+		Privileged: true,
+		Time:       now.Format(time.RFC3339),
+		Kind:       kind,
+		Value:      message,
+	})
+}

rtpconn/webclient.go

@@ -1248,13 +1248,14 @@ func handleAction(c *webClient, a any) error {
 			h := g.GetChatHistory()
 			for _, m := range h {
 				err := c.write(clientMessage{
-					Type:     "chathistory",
+					Type:       "chathistory",
-					Id:       m.Id,
+					Id:         m.Id,
-					Source:   m.Source,
+					Source:     m.Source,
-					Username: m.User,
+					Username:   m.User,
-					Time:     m.Time.Format(time.RFC3339),
+					Privileged: isServerGeneratedChatKind(m.Kind),
-					Value:    m.Value,
+					Time:       m.Time.Format(time.RFC3339),
-					Kind:     m.Kind,
+					Value:      m.Value,
+					Kind:       m.Kind,
 				})
 				if err != nil {
 					return err
@@ -1711,6 +1712,12 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 		if !member("message", c.permissions) {
 			return c.error(hall.UserError("not authorised"))
 		}
+		if isServerGeneratedChatKind(m.Kind) {
+			return c.error(hall.UserError("this message kind is server generated"))
+		}
+
+		source := c.Id()
+		username := c.Username()
 
 		id := m.Id
 		if m.Type == "chat" && m.Dest == "" && id == "" {
@@ -1723,7 +1730,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 		if m.Type == "chat" {
 			if m.Dest == "" {
 				g.AddToChatHistory(
-					id, m.Source, m.Username,
+					id, source, &username,
 					now, m.Kind, m.Value,
 				)
 			}
@@ -1731,9 +1738,9 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 		mm := clientMessage{
 			Type:       m.Type,
 			Id:         id,
-			Source:     m.Source,
+			Source:     source,
 			Dest:       m.Dest,
-			Username:   m.Username,
+			Username:   &username,
 			Privileged: member("op", c.permissions),
 			Time:       now.Format(time.RFC3339),
 			Kind:       m.Kind,
@@ -1817,6 +1824,12 @@ func handleClientMessage(c *webClient, m clientMessage) error {
 			}
 			state := g.UpdateChalkboard(text)
 			broadcastChalkboard(g, state)
+		case "roll":
+			return handleDiceRoll(c, g, m.Value)
+		case "eightball":
+			return handleEightBall(c, g, m.Value)
+		case "coin":
+			return handleCoinFlip(c, g, m.Value)
 		case "lock", "unlock":
 			if !member("op", c.permissions) {
 				return c.error(hall.UserError("not authorised"))

skald-protocol.md

@@ -453,7 +453,24 @@ Finally, a hall action requests that the server act on the current hall.
 
 Currently defined kinds include `clearchat` (not to be confused with the
 `clearchat` user message), `chalkboard`, `lock`, `unlock`, `record`,
-`unrecord`, `subhalls` and `setdata`.  A `chalkboard` hall action updates
+`unrecord`, `roll`, `eightball`, `coin`, `subhalls` and `setdata`.  A `roll`
+hall action requests a server-generated dice roll and requires the `message`
+permission.  Its value is a dice expression such as `2d4`, `10d8 + 5`, or
+`2 D 20 - 1`.  The result is broadcast and stored in chat history as a
+privileged `chat` message of kind `dice`.
+
+An `eightball` hall action asks the Eight Ball a question and also requires
+the `message` permission.  Its value is the question as a string.  The
+server-selected response is broadcast and stored in chat history as a
+privileged `chat` message of kind `eightball`.  Clients must not submit
+`chat` or `usermessage` messages of kind `dice` or `eightball` directly.
+
+A `coin` hall action requests an unbiased, server-generated coin flip.  It
+requires the `message` permission and has no value or an empty string value.
+The result is broadcast and stored in chat history as a privileged `chat`
+message of kind `coin`.  Clients must not submit that message kind directly.
+
+A `chalkboard` hall action updates
 the session-only virtual chalkboard and requires `op`, `admin`, or
 temporary `chalkboard` permission:
 

skald.md

@@ -107,6 +107,21 @@ than navigating the user interface.  Commands start with a slash character
 message to a given user.  Type `/help` to display the list of available
 commands.
 
+Dice may be rolled directly from the chat input with standard dice notation,
+for example `/2d4`, `/10d8 + 5`, or `/2 D 20 - 1`.  Spaces around the `d`
+and modifier are optional, and the `d` is case-insensitive.  Skald generates
+rolls on the server and posts them to the hall as authoritative Dice messages.
+Rolling requires permission to send chat messages.
+
+The `/8ball question` command asks the Eight Ball a question and posts one of
+its classic responses as an authoritative, server-generated message.  The
+longer spelling `/eightball question` is also accepted.  Eight Ball questions,
+like dice rolls, require permission to send chat messages.
+
+The `/coin` command flips a coin and posts the server-generated result as
+heads or tails.  It takes no arguments and requires permission to send chat
+messages.
+
 Below the chat input is a session-only virtual chalkboard.  It is a
 multiline text area suitable for commands, code, and notes that should be
 visible to everyone in the hall.  Operators and administrators may edit

static/skald.js

@@ -3106,6 +3106,12 @@ function addToChatbox(id, peerId, dest, nick, time, privileged, history, kind, m
     footer.classList.add('message-footer');
     if(!peerId)
         container.classList.add('message-system');
+    if(kind === 'dice' && privileged)
+        container.classList.add('message-dice');
+    if(kind === 'eightball' && privileged)
+        container.classList.add('message-eightball');
+    if(kind === 'coin' && privileged)
+        container.classList.add('message-coin');
     if(serverConnection && peerId === serverConnection.id)
         container.classList.add('message-sender');
     if(dest)
@@ -3314,6 +3320,9 @@ function clearChat(id, userId) {
  */
 let commands = {};
 
+const diceCommandRegexp =
+    /^\/\s*[0-9]+\s*[dD]\s*[0-9]+(?:\s*[+-]\s*[0-9]+)?\s*$/;
+
 function operatorPredicate() {
     if(serverConnection && serverConnection.permissions &&
        serverConnection.permissions.indexOf('op') >= 0)
@@ -3348,6 +3357,7 @@ commands.help = {
                 continue;
             cs.push(`/${cmd}${c.parameters?' ' + c.parameters:''}: ${c.description}`);
         }
+        cs.push('/NdS [ +|- modifier]: roll dice; spaces and uppercase D are allowed');
         let shortcuts = '\n\nKeyboard shortcuts:\n' +
             'Control+Alt+H or Alt+Shift+H: Raise or lower hand\n' +
             'Control+Alt+C or Alt+Shift+C: Expand or collapse chat\n' +
@@ -3356,6 +3366,27 @@ commands.help = {
     }
 };
 
+function eightBallCommand(c, r) {
+    serverConnection.hallAction('eightball', r);
+}
+
+commands['8ball'] = {
+    description: 'ask the Eight Ball a question',
+    parameters: 'question',
+    f: eightBallCommand,
+};
+
+commands.eightball = {
+    f: eightBallCommand,
+};
+
+commands.coin = {
+    description: 'flip a coin',
+    f: (c, r) => {
+        serverConnection.hallAction('coin', r);
+    },
+};
+
 commands.me = {
     f: (c, r) => {
         // handled as a special case
@@ -3968,6 +3999,14 @@ function handleInput() {
         if(data.length > 1 && data[1] === '/') {
             message = data.slice(1);
             me = false;
+        } else if(diceCommandRegexp.test(data)) {
+            try {
+                serverConnection.hallAction('roll', data.slice(1));
+            } catch(e) {
+                console.error(e);
+                displayError(e);
+            }
+            return;
         } else {
             let cmd, rest;
             let space = data.indexOf(' ');

webserver/static_accessibility_test.go

@@ -108,6 +108,35 @@ func TestGlobalShortcutAliasesStayDocumented(t *testing.T) {
 	requireContains(t, js, "if(isGlobalShortcut(e, 't'))", "microphone shortcut")
 }
 
+func TestDiceCommandStaysDiscoverableAndUsesServerRolls(t *testing.T) {
+	js := readStaticFile(t, "skald.js")
+
+	requireContains(t, js, "/NdS [ +|- modifier]: roll dice", "dice help")
+	requireContains(t, js, "const diceCommandRegexp", "dice notation parser")
+	requireFunctionContains(t, js, "handleInput", "diceCommandRegexp.test(data)")
+	requireFunctionContains(t, js, "handleInput", "serverConnection.hallAction('roll', data.slice(1))")
+	requireFunctionContains(t, js, "addToChatbox", "kind === 'dice' && privileged")
+}
+
+func TestEightBallCommandsUseServerResponses(t *testing.T) {
+	js := readStaticFile(t, "skald.js")
+
+	requireContains(t, js, "commands['8ball']", "Eight Ball primary command")
+	requireContains(t, js, "description: 'ask the Eight Ball a question'", "Eight Ball help")
+	requireContains(t, js, "commands.eightball", "Eight Ball spelling alias")
+	requireFunctionContains(t, js, "eightBallCommand", "serverConnection.hallAction('eightball', r)")
+	requireFunctionContains(t, js, "addToChatbox", "kind === 'eightball' && privileged")
+}
+
+func TestCoinCommandUsesServerFlip(t *testing.T) {
+	js := readStaticFile(t, "skald.js")
+
+	requireContains(t, js, "commands.coin", "coin command")
+	requireContains(t, js, "description: 'flip a coin'", "coin help")
+	requireContains(t, js, "serverConnection.hallAction('coin', r)", "coin request")
+	requireFunctionContains(t, js, "addToChatbox", "kind === 'coin' && privileged")
+}
+
 func TestTimedUnlockCommandStaysDocumentedAndUsesServerAnnouncements(t *testing.T) {
 	js := readStaticFile(t, "skald.js")
 	protocol := readStaticFile(t, "protocol.js")