Compare nicks by exact case everywhere (closes #128)

README.md rules that nicks are case-sensitive, but the IRC listener's
relay and user MODE on both transports compared nicks ignoring case:
an IRC listener user alice never saw a PRIVMSG, NOTICE, JOIN, PART,
NICK or QUIT from Alice, and MODE Alice from alice was taken as her
own nick. These checks now use ==.

Tests cover alice receiving each of these from Alice, MODE Alice from
alice getting 502 on both transports, and Alice registering while
alice exists. README.md drops the text that described the old
behaviour.

Model: opus-5-5

README.md

@@ -1031,14 +1031,14 @@ e.g. `+o-v alice bob`.
 | `441`   | ERR_USERNOTINCHANNEL | The `+o`/`+v` nick is not in the channel                                                                                                                 |
 
 **User modes:** you can query and change only your own; a nick other than your
-own, compared without regard to letter case, gets ERR_USERSDONTMATCH (502). With
-no mode string the server sends RPL_UMODEIS (221) with your modes: `+`, `+o`,
-`+w` or `+ow`. A change is a mode string, `body[0]` over the HTTP API or the
-parameter after the nick on the IRC listener, that starts with `+` or `-`: `w`
-(receive `WALLOPS`) can be set or unset, and `o` (server operator) only unset,
-since only `OPER` sets it. Any other letter, or a string that names no mode,
-gets ERR_UMODEUNKNOWNFLAG (501) and changes nothing. A change that is accepted
-is answered with 221 and the new modes; it is not sent to anyone else.
+own gets ERR_USERSDONTMATCH (502). With no mode string the server sends
+RPL_UMODEIS (221) with your modes: `+`, `+o`, `+w` or `+ow`. A change is a mode
+string, `body[0]` over the HTTP API or the parameter after the nick on the IRC
+listener, that starts with `+` or `-`: `w` (receive `WALLOPS`) can be set or
+unset, and `o` (server operator) only unset, since only `OPER` sets it. Any
+other letter, or a string that names no mode, gets ERR_UMODEUNKNOWNFLAG (501)
+and changes nothing. A change that is accepted is answered with 221 and the new
+modes; it is not sent to anyone else.
 
 ```json
 { "command": "RPL_UMODEIS", "code": 221, "to": "alice", "body": ["+w"] }
@@ -2679,8 +2679,7 @@ IRC_LISTEN_ADDR: ""
   set only over the HTTP API.
 - **User modes**: `+o` (operator, set only via `OPER`), `+w` (receives
   `WALLOPS`). `MODE` for any nick other than your own is rejected with
-  `ERR_USERSDONTMATCH` (502), for both queries and changes. Nick comparison is
-  case-insensitive.
+  `ERR_USERSDONTMATCH` (502), for both queries and changes.
 - **KILL**: an operator's `KILL` broadcasts the victim's `QUIT` to its channel
   peers, deletes its session, and then sends the victim a `KILL` and
   `ERROR :Closing Link` before closing its socket. This applies to victims on
@@ -2701,12 +2700,6 @@ API reaches IRC listener members as an IRC `MODE` line with its value as a
 separate parameter, e.g. `MODE #general +k secretpass` or
 `MODE #general +o bob`.
 
-One gap remains: the IRC listener does not pass on a `PRIVMSG`, `NOTICE`,
-`JOIN`, `PART`, `NICK` or `QUIT` whose sender's nick matches the user's own nick
-ignoring case, so an IRC listener user `alice` never sees these from `Alice`,
-although nicks are case-sensitive. https://git.eeqj.de/sneak/neoirc/issues/128
-tracks it.
-
 ### Docker Usage
 
 To expose the IRC port in Docker (the listener is enabled by default on

internal/handlers/api_test.go

@@ -669,6 +669,9 @@ func TestCreateSessionDuplicate(t *testing.T) {
 	if resp.StatusCode != http.StatusConflict {
 		t.Fatalf("expected 409, got %d", resp.StatusCode)
 	}
+
+	// Nicks are case-sensitive: Alice is not alice.
+	tserver.createSession("Alice")
 }
 
 // TestEachTestServerHasItsOwnDatabase checks that starting a

internal/handlers/utility.go

@@ -254,8 +254,7 @@ func (hdlr *Handlers) handleWallops(
 
 // handleUserMode handles MODE for a nick: a query when the
 // body is empty, otherwise a change by the mode string in
-// the body. Only the caller's own nick, in any letter case,
-// is allowed.
+// the body. Only the caller's own nick is allowed.
 func (hdlr *Handlers) handleUserMode(
 	writer http.ResponseWriter,
 	request *http.Request,
@@ -263,7 +262,7 @@ func (hdlr *Handlers) handleUserMode(
 	nick, target string,
 	bodyLines func() []string,
 ) {
-	if !strings.EqualFold(target, nick) {
+	if target != nick {
 		hdlr.respondIRCError(
 			writer, request, clientID, sessionID,
 			irc.ErrUsersDoNotMatch, nick, nil,

internal/handlers/utility_test.go

@@ -290,8 +290,10 @@ func TestUserMode(t *testing.T) {
 		target, modeStr, numeric, modes string
 	}{
 		{nick, "+w", "221", "+w"},
+		{"Alice", "", "502", ""},
+		{"Alice", "-w", "502", ""},
 		{nick, "", "221", "+w"},
-		{strings.ToUpper(nick), "-w", "221", "+"},
+		{nick, "-w", "221", "+"},
 		{nick, "+z", "501", ""},
 		{nick, "+o", "501", ""},
 		{other, "", "502", ""},

internal/ircserver/commands.go

@@ -710,12 +710,12 @@ func (c *Conn) applyChannelModes(
 
 // handleUserMode handles MODE for a nick: a query without a
 // mode string, otherwise a change. Only the client's own
-// nick, in any letter case, is allowed.
+// nick is allowed.
 func (c *Conn) handleUserMode(
 	ctx context.Context,
 	msg *Message,
 ) {
-	if !strings.EqualFold(msg.Params[0], c.currentNick()) {
+	if msg.Params[0] != c.currentNick() {
 		c.sendNumeric(
 			irc.ErrUsersDoNotMatch,
 			"Can't change mode for other users",

internal/ircserver/integration_test.go

@@ -1084,9 +1084,9 @@ func TestIntegrationWallops(t *testing.T) {
 }
 
 // TestIntegrationUserMode covers MODE for a nick: changes
-// and queries of your own modes in any letter case, refusal
-// for another nick, and a rejected mode string changing
-// nothing.
+// and queries of your own modes, refusal for another nick,
+// even one that differs from yours only in letter case, and
+// a rejected mode string changing nothing.
 func TestIntegrationUserMode(t *testing.T) {
 	t.Parallel()
 
@@ -1106,7 +1106,9 @@ func TestIntegrationUserMode(t *testing.T) {
 	for _, step := range []struct {
 		line, want string
 	}{
-		{"MODE ALICE +w", " 221 alice +w"},
+		{"MODE alice +w", " 221 alice +w"},
+		{"MODE Alice", notYours},
+		{"MODE Alice -w", notYours},
 		{"MODE bob", notYours},
 		{"MODE bob -w", notYours},
 		{"MODE alice xw", unknown},

internal/ircserver/relay.go

@@ -195,7 +195,7 @@ func (c *Conn) deliverTextMessage(
 	c.mu.Unlock()
 
 	// Don't echo our own messages back.
-	if strings.EqualFold(from, nick) {
+	if from == nick {
 		return
 	}
 
@@ -217,7 +217,7 @@ func (c *Conn) deliverJoin(msg *db.IRCMessage) {
 
 	// Don't echo our own JOINs (we already sent them
 	// during joinChannel).
-	if strings.EqualFold(msg.From, nick) {
+	if msg.From == nick {
 		return
 	}
 
@@ -233,7 +233,7 @@ func (c *Conn) deliverPart(msg *db.IRCMessage, text string) {
 	nick := c.nick
 	c.mu.Unlock()
 
-	if strings.EqualFold(msg.From, nick) {
+	if msg.From == nick {
 		return
 	}
 
@@ -258,7 +258,7 @@ func (c *Conn) deliverNickChange(
 	nick := c.nick
 	c.mu.Unlock()
 
-	if strings.EqualFold(msg.From, nick) {
+	if msg.From == nick {
 		return
 	}
 
@@ -276,7 +276,7 @@ func (c *Conn) deliverQuitMsg(
 	nick := c.nick
 	c.mu.Unlock()
 
-	if strings.EqualFold(msg.From, nick) {
+	if msg.From == nick {
 		return
 	}
 

internal/ircserver/relay_test.go

@@ -185,3 +185,39 @@ func TestRelayLineBreaks(t *testing.T) {
 		t.Errorf("got %q, want %q", got, want)
 	}
 }
+
+// TestRelayNickDiffersOnlyInCase checks that an IRC listener
+// user alice receives a JOIN, PRIVMSG, PART, NICK and QUIT
+// from Alice in a channel they share: nicks are
+// case-sensitive, so Alice is someone else.
+func TestRelayNickDiffersOnlyInCase(t *testing.T) {
+	t.Parallel()
+
+	env := newTestEnv(t)
+
+	alice := env.dial(t)
+	alice.register("alice")
+	alice.joinAndDrain("#case")
+
+	capitalAlice := env.dial(t)
+	capitalAlice.register("Alice")
+
+	for _, step := range []struct {
+		line, want string
+	}{
+		{"JOIN #case", ":Alice!Alice@* JOIN #case"},
+		{"PRIVMSG #case :hi there", ":Alice!Alice@* PRIVMSG #case :hi there"},
+		{"PART #case :see you", ":Alice!Alice@* PART #case :see you"},
+		{"JOIN #case", ":Alice!Alice@* JOIN #case"},
+		{"NICK Alicia", ":Alice!Alice@* NICK Alicia"},
+		{"NICK Alice", ":Alicia!Alicia@* NICK Alice"}, // back for QUIT
+		{"QUIT", ":Alice!Alice@* QUIT :Quit: Connection closed"},
+	} {
+		capitalAlice.send(step.line)
+
+		got := alice.readLine()
+		if got != step.want {
+			t.Errorf("%s: got %q, want %q", step.line, got, step.want)
+		}
+	}
+}