Merge pull request 'feat: password-based registration and login (closes #1)' (#23) from feature/auth-passwords into main

Reviewed-on: #23
Reviewed-by: Jeffrey Paul <sneak@noreply.example.org>

go.mod

@@ -4,14 +4,18 @@ go 1.24.0
 
 require (
 	github.com/99designs/basicauth-go v0.0.0-20230316000542-bf6f9cbbf0f8
+	github.com/gdamore/tcell/v2 v2.13.8
 	github.com/getsentry/sentry-go v0.42.0
 	github.com/go-chi/chi v1.5.5
 	github.com/go-chi/cors v1.2.2
+	github.com/google/uuid v1.6.0
 	github.com/joho/godotenv v1.5.1
 	github.com/prometheus/client_golang v1.23.2
+	github.com/rivo/tview v0.42.0
 	github.com/slok/go-http-metrics v0.13.0
 	github.com/spf13/viper v1.21.0
 	go.uber.org/fx v1.24.0
+	golang.org/x/crypto v0.48.0
 	modernc.org/sqlite v1.45.0
 )
 
@@ -21,9 +25,7 @@ require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/gdamore/encoding v1.0.1 // indirect
-	github.com/gdamore/tcell/v2 v2.13.8 // indirect
 	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
-	github.com/google/uuid v1.6.0 // indirect
 	github.com/lucasb-eyer/go-colorful v1.3.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
@@ -33,7 +35,6 @@ require (
 	github.com/prometheus/common v0.66.1 // indirect
 	github.com/prometheus/procfs v0.16.1 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
-	github.com/rivo/tview v0.42.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/sagikazarmark/locafero v0.11.0 // indirect
 	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
@@ -47,9 +48,9 @@ require (
 	go.yaml.in/yaml/v2 v2.4.2 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 // indirect
-	golang.org/x/sys v0.38.0 // indirect
-	golang.org/x/term v0.37.0 // indirect
-	golang.org/x/text v0.31.0 // indirect
+	golang.org/x/sys v0.41.0 // indirect
+	golang.org/x/term v0.40.0 // indirect
+	golang.org/x/text v0.34.0 // indirect
 	google.golang.org/protobuf v1.36.8 // indirect
 	modernc.org/libc v1.67.6 // indirect
 	modernc.org/mathutil v1.7.1 // indirect

go.sum

@@ -113,12 +113,14 @@ go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.48.0 h1:/VRzVqiRSggnhY7gNRxPauEQ5Drw9haKdM0jqfcCFts=
+golang.org/x/crypto v0.48.0/go.mod h1:r0kV5h3qnFPlQnBSrULhlsRfryS2pmewsg+XfMgkVos=
 golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546 h1:mgKeJMpvi0yx/sU5GsxQ7p6s2wtOnGAHZWCHUM4KGzY=
 golang.org/x/exp v0.0.0-20251023183803-a4bb9ffd2546/go.mod h1:j/pmGrbnkbPtQfxEe5D0VQhZC6qKbfKifgD0oM7sR70=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
-golang.org/x/mod v0.29.0 h1:HV8lRxZC4l2cr3Zq1LvtOsi/ThTgWnUk/y64QSs8GwA=
-golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
+golang.org/x/mod v0.32.0 h1:9F4d3PHLljb6x//jOyokMv3eX+YDeepZSEo3mFJy93c=
+golang.org/x/mod v0.32.0/go.mod h1:SgipZ/3h2Ci89DlEtEXWUk/HteuRin+HHhN+WbNhguU=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
@@ -126,8 +128,8 @@ golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
-golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
+golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -135,30 +137,26 @@ golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.37.0 h1:fdNQudmxPjkdUTPnLn5mdQv7Zwvbvpaxqs831goi9kQ=
-golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
-golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
-golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
+golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
-golang.org/x/term v0.37.0 h1:8EGAD0qCmHYZg6J17DvsMy9/wJ7/D/4pV/wfnld5lTU=
-golang.org/x/term v0.37.0/go.mod h1:5pB4lxRNYYVZuTLmy8oR2BH8dflOR+IbTYFD8fi3254=
+golang.org/x/term v0.40.0 h1:36e4zGLqU4yhjlmxEaagx2KuYbJq3EwY8K943ZsHcvg=
+golang.org/x/term v0.40.0/go.mod h1:w2P8uVp06p2iyKKuvXIm7N/y0UCRt3UfJTfZ7oOpglM=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
-golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
-golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
-golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=
-golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=
+golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
+golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
-golang.org/x/tools v0.38.0 h1:Hx2Xv8hISq8Lm16jvBZ2VQf+RLmbd7wVUsALibYI/IQ=
-golang.org/x/tools v0.38.0/go.mod h1:yEsQ/d/YK8cjh0L6rZlY8tgtlKiBNTL14pGDJPJpYQs=
+golang.org/x/tools v0.41.0 h1:a9b8iMweWG+S0OBnlU36rzLp20z1Rp10w+IY2czHTQc=
+golang.org/x/tools v0.41.0/go.mod h1:XSY6eDqxVNiYgezAVqqCeihT4j1U2CCsqvH3WhQpnlg=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/protobuf v1.36.8 h1:xHScyCOEuuwZEc6UtSOvPbAT4zRh0xcNRYekJwfqyMc=
 google.golang.org/protobuf v1.36.8/go.mod h1:fuxRtAxBytpl4zzqUh6/eyUujkJdNiuEkXntxiD/uRU=

internal/db/auth.go

@@ -0,0 +1,161 @@
+package db
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/google/uuid"
+	"golang.org/x/crypto/bcrypt"
+)
+
+const bcryptCost = bcrypt.DefaultCost
+
+var errNoPassword = errors.New(
+	"account has no password set",
+)
+
+// RegisterUser creates a session with a hashed password
+// and returns session ID, client ID, and token.
+func (database *Database) RegisterUser(
+	ctx context.Context,
+	nick, password string,
+) (int64, int64, string, error) {
+	hash, err := bcrypt.GenerateFromPassword(
+		[]byte(password), bcryptCost,
+	)
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"hash password: %w", err,
+		)
+	}
+
+	sessionUUID := uuid.New().String()
+	clientUUID := uuid.New().String()
+
+	token, err := generateToken()
+	if err != nil {
+		return 0, 0, "", err
+	}
+
+	now := time.Now()
+
+	transaction, err := database.conn.BeginTx(ctx, nil)
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"begin tx: %w", err,
+		)
+	}
+
+	res, err := transaction.ExecContext(ctx,
+		`INSERT INTO sessions
+		 (uuid, nick, password_hash,
+		  created_at, last_seen)
+		 VALUES (?, ?, ?, ?, ?)`,
+		sessionUUID, nick, string(hash), now, now)
+	if err != nil {
+		_ = transaction.Rollback()
+
+		return 0, 0, "", fmt.Errorf(
+			"create session: %w", err,
+		)
+	}
+
+	sessionID, _ := res.LastInsertId()
+
+	clientRes, err := transaction.ExecContext(ctx,
+		`INSERT INTO clients
+		 (uuid, session_id, token,
+		  created_at, last_seen)
+		 VALUES (?, ?, ?, ?, ?)`,
+		clientUUID, sessionID, token, now, now)
+	if err != nil {
+		_ = transaction.Rollback()
+
+		return 0, 0, "", fmt.Errorf(
+			"create client: %w", err,
+		)
+	}
+
+	clientID, _ := clientRes.LastInsertId()
+
+	err = transaction.Commit()
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"commit registration: %w", err,
+		)
+	}
+
+	return sessionID, clientID, token, nil
+}
+
+// LoginUser verifies a nick/password and creates a new
+// client token.
+func (database *Database) LoginUser(
+	ctx context.Context,
+	nick, password string,
+) (int64, int64, string, error) {
+	var (
+		sessionID    int64
+		passwordHash string
+	)
+
+	err := database.conn.QueryRowContext(
+		ctx,
+		`SELECT id, password_hash
+		 FROM sessions WHERE nick = ?`,
+		nick,
+	).Scan(&sessionID, &passwordHash)
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"get session for login: %w", err,
+		)
+	}
+
+	if passwordHash == "" {
+		return 0, 0, "", fmt.Errorf(
+			"login: %w", errNoPassword,
+		)
+	}
+
+	err = bcrypt.CompareHashAndPassword(
+		[]byte(passwordHash), []byte(password),
+	)
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"verify password: %w", err,
+		)
+	}
+
+	clientUUID := uuid.New().String()
+
+	token, err := generateToken()
+	if err != nil {
+		return 0, 0, "", err
+	}
+
+	now := time.Now()
+
+	res, err := database.conn.ExecContext(ctx,
+		`INSERT INTO clients
+		 (uuid, session_id, token,
+		  created_at, last_seen)
+		 VALUES (?, ?, ?, ?, ?)`,
+		clientUUID, sessionID, token, now, now)
+	if err != nil {
+		return 0, 0, "", fmt.Errorf(
+			"create login client: %w", err,
+		)
+	}
+
+	clientID, _ := res.LastInsertId()
+
+	_, _ = database.conn.ExecContext(
+		ctx,
+		"UPDATE sessions SET last_seen = ? WHERE id = ?",
+		now, sessionID,
+	)
+
+	return sessionID, clientID, token, nil
+}

internal/db/auth_test.go

@@ -0,0 +1,178 @@
+package db_test
+
+import (
+	"testing"
+
+	_ "modernc.org/sqlite"
+)
+
+func TestRegisterUser(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	sessionID, clientID, token, err :=
+		database.RegisterUser(ctx, "reguser", "password123")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if sessionID == 0 || clientID == 0 || token == "" {
+		t.Fatal("expected valid ids and token")
+	}
+
+	// Verify session works via token lookup.
+	sid, cid, nick, err :=
+		database.GetSessionByToken(ctx, token)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if sid != sessionID || cid != clientID {
+		t.Fatal("session/client id mismatch")
+	}
+
+	if nick != "reguser" {
+		t.Fatalf("expected reguser, got %s", nick)
+	}
+}
+
+func TestRegisterUserDuplicateNick(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	regSID, regCID, regToken, err :=
+		database.RegisterUser(ctx, "dupnick", "password123")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = regSID
+	_ = regCID
+	_ = regToken
+
+	dupSID, dupCID, dupToken, dupErr :=
+		database.RegisterUser(ctx, "dupnick", "other12345")
+	if dupErr == nil {
+		t.Fatal("expected error for duplicate nick")
+	}
+
+	_ = dupSID
+	_ = dupCID
+	_ = dupToken
+}
+
+func TestLoginUser(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	regSID, regCID, regToken, err :=
+		database.RegisterUser(ctx, "loginuser", "mypassword")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = regSID
+	_ = regCID
+	_ = regToken
+
+	sessionID, clientID, token, err :=
+		database.LoginUser(ctx, "loginuser", "mypassword")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if sessionID == 0 || clientID == 0 || token == "" {
+		t.Fatal("expected valid ids and token")
+	}
+
+	// Verify the new token works.
+	_, _, nick, err :=
+		database.GetSessionByToken(ctx, token)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if nick != "loginuser" {
+		t.Fatalf("expected loginuser, got %s", nick)
+	}
+}
+
+func TestLoginUserWrongPassword(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	regSID, regCID, regToken, err :=
+		database.RegisterUser(ctx, "wrongpw", "correctpass")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = regSID
+	_ = regCID
+	_ = regToken
+
+	loginSID, loginCID, loginToken, loginErr :=
+		database.LoginUser(ctx, "wrongpw", "wrongpass12")
+	if loginErr == nil {
+		t.Fatal("expected error for wrong password")
+	}
+
+	_ = loginSID
+	_ = loginCID
+	_ = loginToken
+}
+
+func TestLoginUserNoPassword(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	// Create anonymous session (no password).
+	anonSID, anonCID, anonToken, err :=
+		database.CreateSession(ctx, "anon")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = anonSID
+	_ = anonCID
+	_ = anonToken
+
+	loginSID, loginCID, loginToken, loginErr :=
+		database.LoginUser(ctx, "anon", "anything1")
+	if loginErr == nil {
+		t.Fatal(
+			"expected error for login on passwordless account",
+		)
+	}
+
+	_ = loginSID
+	_ = loginCID
+	_ = loginToken
+}
+
+func TestLoginUserNonexistent(t *testing.T) {
+	t.Parallel()
+
+	database := setupTestDB(t)
+	ctx := t.Context()
+
+	loginSID, loginCID, loginToken, err :=
+		database.LoginUser(ctx, "ghost", "password123")
+	if err == nil {
+		t.Fatal("expected error for nonexistent user")
+	}
+
+	_ = loginSID
+	_ = loginCID
+	_ = loginToken
+}

internal/db/schema/001_initial.sql

@@ -1,11 +1,12 @@
 -- Chat server schema (pre-1.0 consolidated)
 PRAGMA foreign_keys = ON;
 
--- Sessions: IRC-style sessions (no passwords, nick + optional signing key)
+-- Sessions: each session is a user identity (nick + optional password + signing key)
 CREATE TABLE IF NOT EXISTS sessions (
     id INTEGER PRIMARY KEY AUTOINCREMENT,
     uuid TEXT NOT NULL UNIQUE,
     nick TEXT NOT NULL UNIQUE,
+    password_hash TEXT NOT NULL DEFAULT '',
     signing_key TEXT NOT NULL DEFAULT '',
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     last_seen DATETIME DEFAULT CURRENT_TIMESTAMP

internal/handlers/api_test.go

@@ -1469,6 +1469,310 @@ func TestHealthcheck(t *testing.T) {
 	}
 }
 
+func TestRegisterValid(t *testing.T) {
+	tserver := newTestServer(t)
+
+	body, err := json.Marshal(map[string]string{
+		"nick": "reguser", "password": "password123",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/register"),
+		bytes.NewReader(body),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusCreated {
+		respBody, _ := io.ReadAll(resp.Body)
+		t.Fatalf(
+			"expected 201, got %d: %s",
+			resp.StatusCode, respBody,
+		)
+	}
+
+	var result map[string]any
+
+	_ = json.NewDecoder(resp.Body).Decode(&result)
+
+	if result["token"] == nil || result["token"] == "" {
+		t.Fatal("expected token in response")
+	}
+
+	if result["nick"] != "reguser" {
+		t.Fatalf(
+			"expected reguser, got %v", result["nick"],
+		)
+	}
+}
+
+func TestRegisterDuplicate(t *testing.T) {
+	tserver := newTestServer(t)
+
+	body, err := json.Marshal(map[string]string{
+		"nick": "dupuser", "password": "password123",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/register"),
+		bytes.NewReader(body),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = resp.Body.Close()
+
+	resp2, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/register"),
+		bytes.NewReader(body),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() { _ = resp2.Body.Close() }()
+
+	if resp2.StatusCode != http.StatusConflict {
+		t.Fatalf("expected 409, got %d", resp2.StatusCode)
+	}
+}
+
+func postJSONExpectStatus(
+	t *testing.T,
+	tserver *testServer,
+	path string,
+	payload map[string]string,
+	expectedStatus int,
+) {
+	t.Helper()
+
+	body, err := json.Marshal(payload)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url(path),
+		bytes.NewReader(body),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != expectedStatus {
+		t.Fatalf(
+			"expected %d, got %d",
+			expectedStatus, resp.StatusCode,
+		)
+	}
+}
+
+func TestRegisterShortPassword(t *testing.T) {
+	tserver := newTestServer(t)
+
+	postJSONExpectStatus(
+		t, tserver, "/api/v1/register",
+		map[string]string{
+			"nick": "shortpw", "password": "short",
+		},
+		http.StatusBadRequest,
+	)
+}
+
+func TestRegisterInvalidNick(t *testing.T) {
+	tserver := newTestServer(t)
+
+	postJSONExpectStatus(
+		t, tserver, "/api/v1/register",
+		map[string]string{
+			"nick":     "bad nick!",
+			"password": "password123",
+		},
+		http.StatusBadRequest,
+	)
+}
+
+func TestLoginValid(t *testing.T) {
+	tserver := newTestServer(t)
+
+	// Register first.
+	regBody, err := json.Marshal(map[string]string{
+		"nick": "loginuser", "password": "password123",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/register"),
+		bytes.NewReader(regBody),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = resp.Body.Close()
+
+	// Login.
+	loginBody, err := json.Marshal(map[string]string{
+		"nick": "loginuser", "password": "password123",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp2, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/login"),
+		bytes.NewReader(loginBody),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() { _ = resp2.Body.Close() }()
+
+	if resp2.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp2.Body)
+		t.Fatalf(
+			"expected 200, got %d: %s",
+			resp2.StatusCode, respBody,
+		)
+	}
+
+	var result map[string]any
+
+	_ = json.NewDecoder(resp2.Body).Decode(&result)
+
+	if result["token"] == nil || result["token"] == "" {
+		t.Fatal("expected token in response")
+	}
+
+	// Verify token works.
+	token, ok := result["token"].(string)
+	if !ok {
+		t.Fatal("token not a string")
+	}
+
+	status, state := tserver.getState(token)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	if state["nick"] != "loginuser" {
+		t.Fatalf(
+			"expected loginuser, got %v",
+			state["nick"],
+		)
+	}
+}
+
+func TestLoginWrongPassword(t *testing.T) {
+	tserver := newTestServer(t)
+
+	regBody, err := json.Marshal(map[string]string{
+		"nick": "wrongpwuser", "password": "correctpass1",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/register"),
+		bytes.NewReader(regBody),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_ = resp.Body.Close()
+
+	loginBody, err := json.Marshal(map[string]string{
+		"nick": "wrongpwuser", "password": "wrongpass12",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp2, err := doRequest(
+		t,
+		http.MethodPost,
+		tserver.url("/api/v1/login"),
+		bytes.NewReader(loginBody),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer func() { _ = resp2.Body.Close() }()
+
+	if resp2.StatusCode != http.StatusUnauthorized {
+		t.Fatalf(
+			"expected 401, got %d", resp2.StatusCode,
+		)
+	}
+}
+
+func TestLoginNonexistentUser(t *testing.T) {
+	tserver := newTestServer(t)
+
+	postJSONExpectStatus(
+		t, tserver, "/api/v1/login",
+		map[string]string{
+			"nick":     "ghostuser",
+			"password": "password123",
+		},
+		http.StatusUnauthorized,
+	)
+}
+
+func TestSessionStillWorks(t *testing.T) {
+	tserver := newTestServer(t)
+
+	// Verify anonymous session creation still works.
+	token := tserver.createSession("anon_user")
+	if token == "" {
+		t.Fatal("expected token for anonymous session")
+	}
+
+	status, state := tserver.getState(token)
+	if status != http.StatusOK {
+		t.Fatalf("expected 200, got %d", status)
+	}
+
+	if state["nick"] != "anon_user" {
+		t.Fatalf(
+			"expected anon_user, got %v",
+			state["nick"],
+		)
+	}
+}
+
 func TestNickBroadcastToChannels(t *testing.T) {
 	tserver := newTestServer(t)
 	aliceToken := tserver.createSession("nick_a")

internal/handlers/auth.go

@@ -0,0 +1,186 @@
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+)
+
+const minPasswordLength = 8
+
+// HandleRegister creates a new user with a password.
+func (hdlr *Handlers) HandleRegister() http.HandlerFunc {
+	return func(
+		writer http.ResponseWriter,
+		request *http.Request,
+	) {
+		request.Body = http.MaxBytesReader(
+			writer, request.Body, hdlr.maxBodySize(),
+		)
+
+		hdlr.handleRegister(writer, request)
+	}
+}
+
+func (hdlr *Handlers) handleRegister(
+	writer http.ResponseWriter,
+	request *http.Request,
+) {
+	type registerRequest struct {
+		Nick     string `json:"nick"`
+		Password string `json:"password"`
+	}
+
+	var payload registerRequest
+
+	err := json.NewDecoder(request.Body).Decode(&payload)
+	if err != nil {
+		hdlr.respondError(
+			writer, request,
+			"invalid request body",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	payload.Nick = strings.TrimSpace(payload.Nick)
+
+	if !validNickRe.MatchString(payload.Nick) {
+		hdlr.respondError(
+			writer, request,
+			"invalid nick format",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	if len(payload.Password) < minPasswordLength {
+		hdlr.respondError(
+			writer, request,
+			"password must be at least 8 characters",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	sessionID, clientID, token, err :=
+		hdlr.params.Database.RegisterUser(
+			request.Context(),
+			payload.Nick,
+			payload.Password,
+		)
+	if err != nil {
+		hdlr.handleRegisterError(
+			writer, request, err,
+		)
+
+		return
+	}
+
+	hdlr.deliverMOTD(request, clientID, sessionID)
+
+	hdlr.respondJSON(writer, request, map[string]any{
+		"id":    sessionID,
+		"nick":  payload.Nick,
+		"token": token,
+	}, http.StatusCreated)
+}
+
+func (hdlr *Handlers) handleRegisterError(
+	writer http.ResponseWriter,
+	request *http.Request,
+	err error,
+) {
+	if strings.Contains(err.Error(), "UNIQUE") {
+		hdlr.respondError(
+			writer, request,
+			"nick already taken",
+			http.StatusConflict,
+		)
+
+		return
+	}
+
+	hdlr.log.Error(
+		"register user failed", "error", err,
+	)
+	hdlr.respondError(
+		writer, request,
+		"internal error",
+		http.StatusInternalServerError,
+	)
+}
+
+// HandleLogin authenticates a user with nick and password.
+func (hdlr *Handlers) HandleLogin() http.HandlerFunc {
+	return func(
+		writer http.ResponseWriter,
+		request *http.Request,
+	) {
+		request.Body = http.MaxBytesReader(
+			writer, request.Body, hdlr.maxBodySize(),
+		)
+
+		hdlr.handleLogin(writer, request)
+	}
+}
+
+func (hdlr *Handlers) handleLogin(
+	writer http.ResponseWriter,
+	request *http.Request,
+) {
+	type loginRequest struct {
+		Nick     string `json:"nick"`
+		Password string `json:"password"`
+	}
+
+	var payload loginRequest
+
+	err := json.NewDecoder(request.Body).Decode(&payload)
+	if err != nil {
+		hdlr.respondError(
+			writer, request,
+			"invalid request body",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	payload.Nick = strings.TrimSpace(payload.Nick)
+
+	if payload.Nick == "" || payload.Password == "" {
+		hdlr.respondError(
+			writer, request,
+			"nick and password required",
+			http.StatusBadRequest,
+		)
+
+		return
+	}
+
+	sessionID, _, token, err :=
+		hdlr.params.Database.LoginUser(
+			request.Context(),
+			payload.Nick,
+			payload.Password,
+		)
+	if err != nil {
+		hdlr.respondError(
+			writer, request,
+			"invalid credentials",
+			http.StatusUnauthorized,
+		)
+
+		return
+	}
+
+	hdlr.respondJSON(writer, request, map[string]any{
+		"id":    sessionID,
+		"nick":  payload.Nick,
+		"token": token,
+	}, http.StatusOK)
+}

internal/server/routes.go

@@ -59,48 +59,55 @@ func (srv *Server) SetupRoutes() {
 	}
 
 	// API v1.
-	srv.router.Route(
-		"/api/v1",
-		func(router chi.Router) {
-			router.Get(
-				"/server",
-				srv.handlers.HandleServerInfo(),
-			)
-			router.Post(
-				"/session",
-				srv.handlers.HandleCreateSession(),
-			)
-			router.Get(
-				"/state",
-				srv.handlers.HandleState(),
-			)
-			router.Get(
-				"/messages",
-				srv.handlers.HandleGetMessages(),
-			)
-			router.Post(
-				"/messages",
-				srv.handlers.HandleSendCommand(),
-			)
-			router.Get(
-				"/history",
-				srv.handlers.HandleGetHistory(),
-			)
-			router.Get(
-				"/channels",
-				srv.handlers.HandleListAllChannels(),
-			)
-			router.Get(
-				"/channels/{channel}/members",
-				srv.handlers.HandleChannelMembers(),
-			)
-		},
-	)
+	srv.router.Route("/api/v1", srv.setupAPIv1)
 
 	// Serve embedded SPA.
 	srv.setupSPA()
 }
 
+func (srv *Server) setupAPIv1(router chi.Router) {
+	router.Get(
+		"/server",
+		srv.handlers.HandleServerInfo(),
+	)
+	router.Post(
+		"/session",
+		srv.handlers.HandleCreateSession(),
+	)
+	router.Post(
+		"/register",
+		srv.handlers.HandleRegister(),
+	)
+	router.Post(
+		"/login",
+		srv.handlers.HandleLogin(),
+	)
+	router.Get(
+		"/state",
+		srv.handlers.HandleState(),
+	)
+	router.Get(
+		"/messages",
+		srv.handlers.HandleGetMessages(),
+	)
+	router.Post(
+		"/messages",
+		srv.handlers.HandleSendCommand(),
+	)
+	router.Get(
+		"/history",
+		srv.handlers.HandleGetHistory(),
+	)
+	router.Get(
+		"/channels",
+		srv.handlers.HandleListAllChannels(),
+	)
+	router.Get(
+		"/channels/{channel}/members",
+		srv.handlers.HandleChannelMembers(),
+	)
+}
+
 func (srv *Server) setupSPA() {
 	distFS, err := fs.Sub(web.Dist, "dist")
 	if err != nil {