Add the tier 3 utility IRC commands (closes #87)

USERHOST, VERSION, ADMIN, INFO, TIME, KILL and WALLOPS on both the
HTTP API and the IRC listener, and user mode +w.

Model: opus-5-5

internal/ircserver/commands.go

@@ -345,7 +345,10 @@ func (c *Conn) handleQuit(msg *Message) {
 
 	c.send("ERROR :Closing Link: " + c.hostname +
 		" (Quit: " + reason + ")")
+
+	c.mu.Lock()
 	c.closed = true
+	c.mu.Unlock()
 }
 
 // handleTopic gets or sets a channel topic via the shared
@@ -427,7 +430,7 @@ func (c *Conn) handleMode(
 	if strings.HasPrefix(target, "#") {
 		c.handleChannelMode(ctx, msg)
 	} else {
-		c.handleUserMode(msg)
+		c.handleUserMode(ctx, msg)
 	}
 }
 
@@ -687,10 +690,13 @@ func (c *Conn) applyChannelModes(
 }
 
 // handleUserMode handles MODE for users.
-func (c *Conn) handleUserMode(msg *Message) {
+func (c *Conn) handleUserMode(
+	ctx context.Context,
+	msg *Message,
+) {
 	target := msg.Params[0]
 
-	if !strings.EqualFold(target, c.nick) {
+	if !strings.EqualFold(target, c.currentNick()) {
 		c.sendNumeric(
 			irc.ErrUsersDoNotMatch,
 			"Can't change mode for other users",
@@ -699,8 +705,48 @@ func (c *Conn) handleUserMode(msg *Message) {
 		return
 	}
 
-	// We don't support user modes beyond the basics.
-	c.sendNumeric(irc.RplUmodeIs, "+")
+	// Mode query (no mode string).
+	if len(msg.Params) < 2 { //nolint:mnd
+		modes, err := c.svc.QueryUserMode(
+			ctx, c.sessionID,
+		)
+		if err != nil {
+			c.log.Error(
+				"query user mode failed", "error", err,
+			)
+			c.sendNumeric(
+				irc.ErrUmodeUnknownFlag,
+				"Unable to read user modes",
+			)
+
+			return
+		}
+
+		c.sendNumeric(irc.RplUmodeIs, modes)
+
+		return
+	}
+
+	newModes, err := c.svc.ApplyUserMode(
+		ctx, c.sessionID, msg.Params[1],
+	)
+	if err != nil {
+		var ircErr *service.IRCError
+		if errors.As(err, &ircErr) {
+			c.sendNumeric(ircErr.Code, ircErr.Message)
+
+			return
+		}
+
+		c.sendNumeric(
+			irc.ErrUmodeUnknownFlag,
+			"Unknown MODE flag",
+		)
+
+		return
+	}
+
+	c.sendNumeric(irc.RplUmodeIs, newModes)
 }
 
 // handleNames replies with channel member list.
@@ -1292,3 +1338,180 @@ func (c *Conn) handleUserhost(
 		strings.Join(replies, " "),
 	)
 }
+
+// handleVersion replies with the server version string.
+func (c *Conn) handleVersion() {
+	c.sendNumeric(
+		irc.RplVersion,
+		c.svc.ServerVersion()+".", c.serverSfx,
+		"",
+	)
+}
+
+// handleAdmin replies with server admin info.
+func (c *Conn) handleAdmin() {
+	srvName := c.serverSfx
+
+	c.sendNumeric(
+		irc.RplAdminMe,
+		srvName, "Administrative info",
+	)
+
+	c.sendNumeric(
+		irc.RplAdminLoc1,
+		"neoirc server",
+	)
+
+	c.sendNumeric(
+		irc.RplAdminLoc2,
+		"IRC over HTTP",
+	)
+
+	c.sendNumeric(
+		irc.RplAdminEmail,
+		"admin@"+srvName,
+	)
+}
+
+// handleInfo replies with server software info.
+func (c *Conn) handleInfo() {
+	for _, line := range c.svc.InfoLines() {
+		c.sendNumeric(irc.RplInfo, line)
+	}
+
+	c.sendNumeric(
+		irc.RplEndOfInfo,
+		"End of /INFO list",
+	)
+}
+
+// handleTime replies with the server's current time.
+func (c *Conn) handleTime() {
+	srvName := c.serverSfx
+
+	c.sendNumeric(
+		irc.RplTime,
+		srvName, time.Now().Format(time.RFC1123),
+	)
+}
+
+// handleKillCmd forcibly disconnects a target user (oper
+// only).
+func (c *Conn) handleKillCmd(
+	ctx context.Context,
+	msg *Message,
+) {
+	isOper, err := c.database.IsSessionOper(
+		ctx, c.sessionID,
+	)
+	if err != nil || !isOper {
+		c.sendNumeric(
+			irc.ErrNoPrivileges,
+			"Permission Denied- "+
+				"You're not an IRC operator",
+		)
+
+		return
+	}
+
+	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			"KILL", "Not enough parameters",
+		)
+
+		return
+	}
+
+	targetNick := msg.Params[0]
+
+	reason := "KILLed"
+	if len(msg.Params) > 1 {
+		reason = msg.Params[1]
+	}
+
+	killerNick := c.currentNick()
+
+	if strings.EqualFold(targetNick, killerNick) {
+		c.sendNumeric(
+			irc.ErrCantKillServer,
+			"You cannot KILL yourself",
+		)
+
+		return
+	}
+
+	targetSID, lookupErr := c.database.GetSessionByNick(
+		ctx, targetNick,
+	)
+	if lookupErr != nil {
+		c.sendNumeric(
+			irc.ErrNoSuchNick,
+			targetNick, "No such nick/channel",
+		)
+
+		return
+	}
+
+	quitReason := "Killed (" + killerNick +
+		" (" + reason + "))"
+
+	// KillSession broadcasts the QUIT, deletes the session
+	// and disconnects the victim's wire connection.
+	c.svc.KillSession(
+		ctx, targetSID, targetNick, quitReason,
+	)
+}
+
+// handleWallopsCmd broadcasts to all +w users (oper only).
+func (c *Conn) handleWallopsCmd(
+	ctx context.Context,
+	msg *Message,
+) {
+	isOper, err := c.database.IsSessionOper(
+		ctx, c.sessionID,
+	)
+	if err != nil || !isOper {
+		c.sendNumeric(
+			irc.ErrNoPrivileges,
+			"Permission Denied- "+
+				"You're not an IRC operator",
+		)
+
+		return
+	}
+
+	if len(msg.Params) < 1 {
+		c.sendNumeric(
+			irc.ErrNeedMoreParams,
+			"WALLOPS", "Not enough parameters",
+		)
+
+		return
+	}
+
+	message := msg.Params[0]
+
+	wallopsSIDs, wallErr := c.database.
+		GetWallopsSessionIDs(ctx)
+	if wallErr != nil {
+		c.log.Error(
+			"get wallops sessions failed",
+			"error", wallErr,
+		)
+
+		return
+	}
+
+	if len(wallopsSIDs) > 0 {
+		body, mErr := json.Marshal([]string{message})
+		if mErr != nil {
+			return
+		}
+
+		_, _, _ = c.svc.FanOut(
+			ctx, irc.CmdWallops, c.currentNick(), "*",
+			nil, body, nil, wallopsSIDs,
+		)
+	}
+}

internal/ircserver/conn.go

@@ -22,6 +22,7 @@ const (
 	maxLineLen      = 512
 	readTimeout     = 5 * time.Minute
 	writeTimeout    = 30 * time.Second
+	killWriteWindow = 2 * time.Second
 	dnsTimeout      = 3 * time.Second
 	pollInterval    = 100 * time.Millisecond
 	pingInterval    = 90 * time.Second
@@ -46,6 +47,12 @@ type Conn struct {
 	serverSfx string
 	commands  map[string]cmdHandler
 
+	// writeMu serializes writes to conn.  A connection is
+	// written to by its own read loop, by its relay
+	// goroutine, and — when an operator KILLs it — by
+	// another client's goroutine.
+	writeMu sync.Mutex
+
 	mu        sync.Mutex
 	nick      string
 	username  string
@@ -62,6 +69,7 @@ type Conn struct {
 
 	lastQueueID int64
 	closed      bool
+	killed      bool
 }
 
 func newConn(
@@ -97,6 +105,57 @@ func newConn(
 	return conn
 }
 
+// Disconnect ends the connection for an operator KILL from
+// either transport: the victim is sent KILL and ERROR, then
+// its socket is closed, which ends serve() and with it the
+// relay goroutine. It is called from the killer's goroutine
+// and does not wait for the writes, so a victim that has
+// stopped reading cannot stall the killer.
+func (c *Conn) Disconnect(reason string) {
+	c.mu.Lock()
+
+	if c.closed {
+		c.mu.Unlock()
+
+		return
+	}
+
+	c.closed = true
+	c.killed = true
+	nick := c.nick
+	host := c.hostname
+	c.mu.Unlock()
+
+	if nick == "" {
+		nick = "*"
+	}
+
+	go func() {
+		c.notifyKilledAndClose(nick, host, reason)
+	}()
+}
+
+// notifyKilledAndClose sends a killed victim the KILL and
+// ERROR lines, each bounded by killWriteWindow, and then
+// closes its socket.
+func (c *Conn) notifyKilledAndClose(
+	nick, host, reason string,
+) {
+	defer c.conn.Close() //nolint:errcheck
+
+	c.sendWithin(
+		killWriteWindow,
+		FormatMessage(
+			c.serverSfx, irc.CmdKill, nick, reason,
+		),
+	)
+	c.sendWithin(
+		killWriteWindow,
+		"ERROR :Closing Link: "+host+
+			" ("+reason+")",
+	)
+}
+
 // buildCommandMap returns a map from IRC command strings
 // to handler functions.
 func (c *Conn) buildCommandMap() map[string]cmdHandler {
@@ -129,7 +188,13 @@ func (c *Conn) buildCommandMap() map[string]cmdHandler {
 		"CAP": func(_ context.Context, msg *Message) {
 			c.handleCAP(msg)
 		},
-		"USERHOST": c.handleUserhost,
+		"USERHOST":     c.handleUserhost,
+		irc.CmdVersion: func(context.Context, *Message) { c.handleVersion() },
+		irc.CmdAdmin:   func(context.Context, *Message) { c.handleAdmin() },
+		irc.CmdInfo:    func(context.Context, *Message) { c.handleInfo() },
+		irc.CmdTime:    func(context.Context, *Message) { c.handleTime() },
+		irc.CmdKill:    c.handleKillCmd,
+		irc.CmdWallops: c.handleWallopsCmd,
 	}
 }
 
@@ -180,7 +245,7 @@ func (c *Conn) serve(ctx context.Context) {
 
 		c.handleMessage(ctx, msg)
 
-		if c.closed {
+		if c.isClosed() {
 			return
 		}
 	}
@@ -189,24 +254,65 @@ func (c *Conn) serve(ctx context.Context) {
 func (c *Conn) cleanup(ctx context.Context) {
 	c.mu.Lock()
 	wasRegistered := c.registered
+	wasKilled := c.killed
 	sessID := c.sessionID
 	nick := c.nick
 	c.closed = true
 	c.mu.Unlock()
 
 	if wasRegistered && sessID > 0 {
-		c.svc.BroadcastQuit(
-			ctx, sessID, nick, "Connection closed",
-		)
+		c.svc.UnregisterWireConn(sessID, c)
+
+		// A KILLed session has already been broadcast and
+		// deleted by the killer; broadcasting again would
+		// fan out a QUIT for a session row that is gone.
+		if !wasKilled {
+			c.svc.BroadcastQuit(
+				ctx, sessID, nick, "Connection closed",
+			)
+		}
 	}
 
 	c.conn.Close() //nolint:errcheck,gosec
 }
 
+// isClosed reports whether the connection has been marked
+// for teardown, either by QUIT or by an operator KILL.
+func (c *Conn) isClosed() bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.closed
+}
+
+// currentNick returns the connection's registered nick.
+// c.nick is written under c.mu during registration and
+// NICK changes, so every read must take the mutex.
+func (c *Conn) currentNick() string {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	return c.nick
+}
+
 // send writes a formatted IRC line to the connection.
 func (c *Conn) send(line string) {
+	c.sendWithin(writeTimeout, line)
+}
+
+// sendWithin writes a formatted IRC line to the connection
+// under the given write deadline.  Callers that must not be
+// held hostage by an unresponsive peer pass a shorter window
+// than writeTimeout.
+func (c *Conn) sendWithin(
+	timeout time.Duration,
+	line string,
+) {
+	c.writeMu.Lock()
+	defer c.writeMu.Unlock()
+
 	_ = c.conn.SetWriteDeadline(
-		time.Now().Add(writeTimeout),
+		time.Now().Add(timeout),
 	)
 
 	_, _ = fmt.Fprintf(c.conn, "%s\r\n", line)
@@ -387,7 +493,10 @@ func (c *Conn) completeRegistration(ctx context.Context) {
 			"failed to create session", "error", err,
 		)
 		c.send("ERROR :Internal server error")
+
+		c.mu.Lock()
 		c.closed = true
+		c.mu.Unlock()
 
 		return
 	}
@@ -398,6 +507,10 @@ func (c *Conn) completeRegistration(ctx context.Context) {
 	c.registered = true
 	c.mu.Unlock()
 
+	// Make this connection reachable by session ID so that
+	// KILL from either transport can disconnect it.
+	c.svc.RegisterWireConn(sessionID, c)
+
 	// If PASS was provided before registration, set the
 	// session password.
 	if c.passWord != "" && len(c.passWord) >= minPasswordLen {

internal/ircserver/conn_test.go

@@ -0,0 +1,128 @@
+package ircserver_test
+
+import (
+	"bufio"
+	"log/slog"
+	"net"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/neoirc/internal/config"
+	"sneak.berlin/go/neoirc/internal/ircserver"
+)
+
+// disconnectBudget is how long Disconnect is allowed to
+// take when the victim never reads.  It is far below the
+// 30s writeTimeout that the old synchronous implementation
+// would have burned on each of its two writes.
+const disconnectBudget = 2 * time.Second
+
+// TestDisconnectDoesNotBlockOnUnresponsiveVictim proves
+// that an operator KILL cannot be stalled by its target.
+// The victim's socket is a net.Pipe, so every write blocks
+// until the peer reads and the peer here never does.  The
+// old implementation performed both notification writes on
+// the killer's goroutine, which wedged the operator's own
+// serve() loop on the IRC path and the API request on the
+// HTTP path for as long as the victim cared to stay silent.
+func TestDisconnectDoesNotBlockOnUnresponsiveVictim(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	serverSide, clientSide := net.Pipe()
+
+	t.Cleanup(func() {
+		_ = clientSide.Close()
+	})
+
+	log := slog.New(slog.NewTextHandler(
+		os.Stderr,
+		&slog.HandlerOptions{Level: slog.LevelError}, //nolint:exhaustruct
+	))
+	cfg := &config.Config{ //nolint:exhaustruct
+		ServerName: "test.irc",
+	}
+
+	victim := ircserver.NewTestConn(
+		log, cfg, serverSide, "victim",
+	)
+
+	returned := make(chan struct{})
+
+	go func() {
+		victim.Disconnect("killed by oper")
+		close(returned)
+	}()
+
+	select {
+	case <-returned:
+	case <-time.After(disconnectBudget):
+		t.Fatal(
+			"Disconnect blocked on the victim's socket; " +
+				"the killer must not be held hostage",
+		)
+	}
+}
+
+// TestDisconnectNotifiesAndClosesVictim is the other half
+// of the contract: moving the notification off the killer's
+// goroutine must not lose it.  A victim that does read gets
+// both the KILL and the ERROR line, and then its socket is
+// closed so its read loop unblocks.
+func TestDisconnectNotifiesAndClosesVictim(t *testing.T) {
+	t.Parallel()
+
+	serverSide, clientSide := net.Pipe()
+
+	t.Cleanup(func() {
+		_ = clientSide.Close()
+	})
+
+	log := slog.New(slog.NewTextHandler(
+		os.Stderr,
+		&slog.HandlerOptions{Level: slog.LevelError}, //nolint:exhaustruct
+	))
+	cfg := &config.Config{ //nolint:exhaustruct
+		ServerName: "test.irc",
+	}
+
+	victim := ircserver.NewTestConn(
+		log, cfg, serverSide, "victim",
+	)
+
+	lines := make(chan []string, 1)
+
+	go func() {
+		var got []string
+
+		scanner := bufio.NewScanner(clientSide)
+		for scanner.Scan() {
+			got = append(got, scanner.Text())
+		}
+
+		lines <- got
+	}()
+
+	victim.Disconnect("killed by oper")
+
+	var got []string
+
+	select {
+	case got = <-lines:
+	case <-time.After(5 * time.Second):
+		t.Fatal("victim socket was never closed")
+	}
+
+	joined := strings.Join(got, "\n")
+
+	if !strings.Contains(joined, "KILL victim") {
+		t.Errorf("missing KILL line, got: %q", joined)
+	}
+
+	if !strings.Contains(joined, "ERROR :Closing Link:") {
+		t.Errorf("missing ERROR line, got: %q", joined)
+	}
+}

internal/ircserver/export_test.go

@@ -4,10 +4,12 @@ import (
 	"context"
 	"log/slog"
 	"net"
+	"time"
 
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/service"
 )
 
@@ -19,8 +21,14 @@ func NewTestServer(
 	database *db.Database,
 	brk *broker.Broker,
 ) *Server {
+	globs := &globals.Globals{
+		Appname:   "neoirc",
+		Version:   "test",
+		StartTime: time.Now(),
+	}
+
 	svc := service.NewTestService(
-		database, brk, cfg, log,
+		database, brk, cfg, globs, log,
 	)
 
 	return &Server{ //nolint:exhaustruct
@@ -47,3 +55,21 @@ func (s *Server) Stop() {
 func (s *Server) Listener() net.Listener {
 	return s.listener
 }
+
+// NewTestConn wraps an already-established net.Conn in a
+// Conn so tests can drive connection-level behaviour such
+// as Disconnect without standing up a whole server.
+func NewTestConn(
+	log *slog.Logger,
+	cfg *config.Config,
+	tcpConn net.Conn,
+	nick string,
+) *Conn {
+	conn := newConn(
+		context.Background(), tcpConn, log,
+		nil, nil, cfg, nil,
+	)
+	conn.nick = nick
+
+	return conn
+}

internal/ircserver/integration_test.go

@@ -762,6 +762,336 @@ func TestIntegrationTwoClients(t *testing.T) {
 	)
 }
 
+// ── Tier 3 Utility Command Integration Tests ──────────
+
+// TestIntegrationUserhost verifies the USERHOST command
+// returns user@host info for connected nicks.
+func TestIntegrationUserhost(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	// Query single nick.
+	alice.send("USERHOST bob")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 302 ")
+	})
+	assertContains(
+		t, aliceReply, " 302 ",
+		"RPL_USERHOST",
+	)
+	assertContains(
+		t, aliceReply, "bob",
+		"USERHOST contains queried nick",
+	)
+
+	// Query multiple nicks.
+	bob.send("USERHOST alice bob")
+
+	bobReply := bob.readUntil(func(l string) bool {
+		return strings.Contains(l, " 302 ")
+	})
+	assertContains(
+		t, bobReply, " 302 ",
+		"RPL_USERHOST multi-nick",
+	)
+	assertContains(
+		t, bobReply, "alice",
+		"USERHOST multi contains alice",
+	)
+	assertContains(
+		t, bobReply, "bob",
+		"USERHOST multi contains bob",
+	)
+}
+
+// TestIntegrationVersion verifies the VERSION command
+// returns the server version string.
+func TestIntegrationVersion(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("VERSION")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 351 ")
+	})
+	assertContains(
+		t, aliceReply, " 351 ",
+		"RPL_VERSION",
+	)
+	assertContains(
+		t, aliceReply, "neoirc",
+		"VERSION reply contains server name",
+	)
+}
+
+// TestIntegrationAdmin verifies the ADMIN command returns
+// server admin info (256–259 numerics).
+func TestIntegrationAdmin(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("ADMIN")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 259 ")
+	})
+	assertContains(
+		t, aliceReply, " 256 ",
+		"RPL_ADMINME",
+	)
+	assertContains(
+		t, aliceReply, " 257 ",
+		"RPL_ADMINLOC1",
+	)
+	assertContains(
+		t, aliceReply, " 258 ",
+		"RPL_ADMINLOC2",
+	)
+	assertContains(
+		t, aliceReply, " 259 ",
+		"RPL_ADMINEMAIL",
+	)
+}
+
+// TestIntegrationInfo verifies the INFO command returns
+// server information (371/374 numerics).
+func TestIntegrationInfo(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("INFO")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 374 ")
+	})
+	assertContains(
+		t, aliceReply, " 371 ",
+		"RPL_INFO",
+	)
+	assertContains(
+		t, aliceReply, " 374 ",
+		"RPL_ENDOFINFO",
+	)
+	assertContains(
+		t, aliceReply, "neoirc",
+		"INFO reply mentions server name",
+	)
+}
+
+// TestIntegrationTime verifies the TIME command returns
+// the server time (391 numeric).
+func TestIntegrationTime(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("TIME")
+
+	aliceReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 391 ")
+	})
+	assertContains(
+		t, aliceReply, " 391 ",
+		"RPL_TIME",
+	)
+	assertContains(
+		t, aliceReply, "test.irc",
+		"TIME reply includes server name",
+	)
+}
+
+// TestIntegrationKill verifies the KILL command: oper can
+// kill a user, non-oper cannot, and — most importantly —
+// that the victim is actually disconnected rather than
+// merely announced as having quit.
+//
+//nolint:funlen // one KILL scenario asserted end to end
+func TestIntegrationKill(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithOper(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	// Both join a channel so KILL's QUIT is visible.
+	alice.joinAndDrain("#killtest")
+	bob.joinAndDrain("#killtest")
+
+	// Drain alice's view of bob's join.
+	alice.readUntil(func(l string) bool {
+		return strings.Contains(l, "JOIN") &&
+			strings.Contains(l, "bob")
+	})
+
+	// Non-oper KILL should fail.
+	alice.send("KILL bob :nope")
+
+	aliceKillFail := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 481 ")
+	})
+	assertContains(
+		t, aliceKillFail, " 481 ",
+		"ERR_NOPRIVILEGES for non-oper KILL",
+	)
+
+	// alice becomes oper.
+	alice.send("OPER testoper testpass")
+	alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 381 ")
+	})
+
+	// Oper KILL should succeed.
+	alice.send("KILL bob :bad behavior")
+
+	// The victim must be told why and then disconnected.
+	// Reading to EOF is the assertion that matters: a KILL
+	// that only broadcasts a QUIT leaves bob holding a
+	// socket that looks alive but delivers nothing.
+	bobLines := bob.readUntilClosed()
+	assertContains(
+		t, bobLines, "KILL",
+		"victim receives KILL before disconnect",
+	)
+	assertContains(
+		t, bobLines, "ERROR :Closing Link",
+		"victim receives ERROR before disconnect",
+	)
+	assertContains(
+		t, bobLines, "bad behavior",
+		"KILL reason delivered to victim",
+	)
+
+	// alice should see bob's QUIT relay.
+	aliceSeesQuit := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, "QUIT") &&
+			strings.Contains(l, "bob")
+	})
+	assertContains(
+		t, aliceSeesQuit, "Killed",
+		"KILL reason in QUIT message",
+	)
+
+	// bob must be gone from the channel member list.
+	alice.send("NAMES #killtest")
+
+	aliceNames := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 366 ")
+	})
+	assertContains(
+		t, aliceNames, "alice",
+		"alice still in NAMES after killing bob",
+	)
+	assertNotContains(
+		t, aliceNames, "bob",
+		"killed user must not appear in NAMES",
+	)
+
+	// ...nor from WHO.
+	alice.send("WHO #killtest")
+
+	aliceWho := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 315 ")
+	})
+	assertNotContains(
+		t, aliceWho, "bob",
+		"killed user must not appear in WHO",
+	)
+
+	// KILL nonexistent nick.
+	alice.send("KILL nobody123 :gone")
+
+	aliceNoSuch := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 401 ")
+	})
+	assertContains(
+		t, aliceNoSuch, " 401 ",
+		"ERR_NOSUCHNICK for KILL missing target",
+	)
+}
+
+// TestIntegrationWallops verifies the WALLOPS command:
+// oper can broadcast to +w users.
+func TestIntegrationWallops(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithOper(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	bob := env.dial(t)
+	bob.register("bob")
+
+	// Non-oper WALLOPS should fail.
+	alice.send("WALLOPS :test broadcast")
+
+	aliceWallopsFail := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 481 ")
+	})
+	assertContains(
+		t, aliceWallopsFail, " 481 ",
+		"ERR_NOPRIVILEGES for non-oper WALLOPS",
+	)
+
+	// alice becomes oper.
+	alice.send("OPER testoper testpass")
+	alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 381 ")
+	})
+
+	// bob sets +w to receive wallops.
+	bob.send("MODE bob +w")
+	bob.readUntil(func(l string) bool {
+		return strings.Contains(l, " 221 ")
+	})
+
+	// alice sends WALLOPS.
+	alice.send("WALLOPS :important announcement")
+
+	// bob (who has +w) should receive it.
+	bobWallops := bob.readUntil(func(l string) bool {
+		return strings.Contains(
+			l, "important announcement",
+		)
+	})
+	assertContains(
+		t, bobWallops, "important announcement",
+		"bob receives WALLOPS message",
+	)
+	assertContains(
+		t, bobWallops, "WALLOPS",
+		"message is WALLOPS command",
+	)
+}
+
 // TestIntegrationModeSecret tests +s (secret) channel
 // mode — verifies that +s can be set and the mode is
 // reflected in MODE queries.
@@ -915,3 +1245,80 @@ func TestIntegrationThirdClientObserver(t *testing.T) {
 		"carol receives trio message",
 	)
 }
+
+// assertNoEmptyParam fails if any line contains a doubled
+// space, which is what FormatMessage emits for an empty
+// non-trailing parameter.  A numeric whose server-name
+// parameter came out empty is malformed on the wire even
+// though it still contains the numeric code, so the other
+// assertions in this file would not catch it.
+func assertNoEmptyParam(
+	t *testing.T,
+	lines []string,
+	context string,
+) {
+	t.Helper()
+
+	for _, line := range lines {
+		if strings.Contains(line, "  ") {
+			t.Errorf(
+				"%s: empty parameter in wire line: %q",
+				context, line,
+			)
+		}
+	}
+}
+
+// TestIntegrationDefaultServerNameFallback runs the wire
+// server with SERVER_NAME unset, which is the shipped
+// default from config.go, and verifies that VERSION, ADMIN
+// and TIME fall back to "neoirc" exactly as the HTTP path
+// does instead of emitting an empty server-name parameter.
+//
+// Every other wire test hardcodes ServerName: "test.irc",
+// so none of them exercise the default configuration.
+func TestIntegrationDefaultServerNameFallback(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnvWithServerName(t, "")
+
+	alice := env.dial(t)
+	alice.register("alice")
+
+	alice.send("VERSION")
+
+	versionReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 351 ")
+	})
+	assertNoEmptyParam(t, versionReply, "VERSION")
+	assertContains(
+		t, versionReply, "neoirc",
+		"VERSION falls back to default server name",
+	)
+
+	alice.send("ADMIN")
+
+	adminReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 259 ")
+	})
+	assertNoEmptyParam(t, adminReply, "ADMIN")
+	assertContains(
+		t, adminReply, " 256 alice neoirc ",
+		"RPL_ADMINME names the default server",
+	)
+	assertContains(
+		t, adminReply, "admin@neoirc",
+		"RPL_ADMINEMAIL is a well-formed address",
+	)
+
+	alice.send("TIME")
+
+	timeReply := alice.readUntil(func(l string) bool {
+		return strings.Contains(l, " 391 ")
+	})
+	assertNoEmptyParam(t, timeReply, "TIME")
+	assertContains(
+		t, timeReply, " 391 alice neoirc ",
+		"RPL_TIME names the default server",
+	)
+}

internal/ircserver/relay.go

@@ -120,6 +120,8 @@ func (c *Conn) deliverIRCMessage(
 		c.deliverKickMsg(msg, text)
 	case command == "INVITE":
 		c.deliverInviteMsg(msg, text)
+	case command == irc.CmdWallops:
+		c.deliverWallops(msg, text)
 	case command == irc.CmdMode:
 		c.deliverMode(msg, text)
 	case command == irc.CmdPing:
@@ -337,6 +339,18 @@ func (c *Conn) deliverInviteMsg(
 	c.sendFromServer("NOTICE", nick, text)
 }
 
+// deliverWallops sends a WALLOPS notification.
+func (c *Conn) deliverWallops(
+	msg *db.IRCMessage,
+	text string,
+) {
+	prefix := msg.From + "!" + msg.From + "@*"
+
+	c.send(FormatMessage(
+		prefix, irc.CmdWallops, text,
+	))
+}
+
 // deliverMode sends a MODE change notification.
 func (c *Conn) deliverMode(
 	msg *db.IRCMessage,

internal/ircserver/server_test.go

@@ -39,6 +39,20 @@ type testEnv struct {
 func newTestEnv(t *testing.T) *testEnv {
 	t.Helper()
 
+	return newTestEnvWithServerName(t, "test.irc")
+}
+
+// newTestEnvWithServerName creates a test environment with
+// an explicit SERVER_NAME. Passing "" exercises the shipped
+// default from config.go, under which the server must fall
+// back to "neoirc" rather than emitting an empty
+// server-name parameter.
+func newTestEnvWithServerName(
+	t *testing.T,
+	serverName string,
+) *testEnv {
+	t.Helper()
+
 	dsn := fmt.Sprintf(
 		"file:%s?mode=memory&cache=shared&_journal_mode=WAL",
 		t.Name(),
@@ -68,7 +82,7 @@ func newTestEnv(t *testing.T) *testEnv {
 	brk := broker.New()
 
 	cfg := &config.Config{ //nolint:exhaustruct
-		ServerName: "test.irc",
+		ServerName: serverName,
 		MOTD:       "Welcome to test IRC",
 	}
 
@@ -115,6 +129,87 @@ func newTestEnv(t *testing.T) *testEnv {
 	}
 }
 
+// newTestEnvWithOper creates a test environment with oper
+// credentials configured.
+func newTestEnvWithOper(t *testing.T) *testEnv {
+	t.Helper()
+
+	dsn := fmt.Sprintf(
+		"file:%s?mode=memory&cache=shared&_journal_mode=WAL",
+		t.Name(),
+	)
+
+	conn, err := sql.Open("sqlite", dsn)
+	if err != nil {
+		t.Fatalf("open db: %v", err)
+	}
+
+	conn.SetMaxOpenConns(1)
+
+	_, err = conn.ExecContext(
+		t.Context(), "PRAGMA foreign_keys = ON",
+	)
+	if err != nil {
+		t.Fatalf("pragma: %v", err)
+	}
+
+	database := db.NewTestDatabaseFromConn(conn)
+
+	err = database.RunMigrations(t.Context())
+	if err != nil {
+		t.Fatalf("migrate: %v", err)
+	}
+
+	brk := broker.New()
+
+	cfg := &config.Config{ //nolint:exhaustruct
+		ServerName:   "test.irc",
+		MOTD:         "Welcome to test IRC",
+		OperName:     "testoper",
+		OperPassword: "testpass",
+	}
+
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+
+	addr := listener.Addr().String()
+
+	err = listener.Close()
+	if err != nil {
+		t.Fatalf("close listener: %v", err)
+	}
+
+	log := slog.New(slog.NewTextHandler(
+		os.Stderr,
+		&slog.HandlerOptions{Level: slog.LevelError}, //nolint:exhaustruct
+	))
+
+	srv := ircserver.NewTestServer(log, cfg, database, brk)
+
+	err = srv.Start(addr)
+	if err != nil {
+		t.Fatalf("start irc server: %v", err)
+	}
+
+	t.Cleanup(func() {
+		srv.Stop()
+
+		err := conn.Close()
+		if err != nil {
+			t.Logf("close db: %v", err)
+		}
+	})
+
+	return &testEnv{
+		database: database,
+		brk:      brk,
+		cfg:      cfg,
+		srv:      srv,
+	}
+}
+
 // dial connects to the test server.
 func (env *testEnv) dial(t *testing.T) *testClient {
 	t.Helper()
@@ -215,6 +310,36 @@ func (tc *testClient) register(nick string) []string {
 	})
 }
 
+// readUntilClosed reads until the peer closes the
+// connection, returning the lines received first.  It
+// fails the test if the connection is still open when the
+// read deadline expires, which is what a KILL that never
+// terminates the victim's socket looks like.
+func (tc *testClient) readUntilClosed() []string {
+	tc.t.Helper()
+
+	_ = tc.conn.SetReadDeadline(
+		time.Now().Add(testTimeout),
+	)
+
+	var lines []string
+
+	for tc.scanner.Scan() {
+		lines = append(lines, tc.scanner.Text())
+	}
+
+	err := tc.scanner.Err()
+	if err != nil {
+		tc.t.Fatalf(
+			"expected EOF on victim socket, got %v "+
+				"(lines: %v)",
+			err, lines,
+		)
+	}
+
+	return lines
+}
+
 // assertContains checks that at least one line matches the
 // given substring.
 func assertContains(
@@ -233,6 +358,27 @@ func assertContains(
 	t.Errorf("did not find %q in output: %s", substr, description)
 }
 
+// assertNotContains checks that no line matches the given
+// substring.
+func assertNotContains(
+	t *testing.T,
+	lines []string,
+	substr, description string,
+) {
+	t.Helper()
+
+	for _, line := range lines {
+		if strings.Contains(line, substr) {
+			t.Errorf(
+				"unexpectedly found %q in output: %s",
+				substr, description,
+			)
+
+			return
+		}
+	}
+}
+
 // joinAndDrain joins a channel and reads until
 // RPL_ENDOFNAMES.
 func (tc *testClient) joinAndDrain(channel string) {