have a clear error on taken aliases

fixes #194

muxrpc/handlers/alias/handler.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strings"
 
@@ -99,6 +100,10 @@ func (h Handler) Register(ctx context.Context, req *muxrpc.Request) (interface{}
 
 	err = h.db.Register(ctx, confirmation.Alias, confirmation.UserID, confirmation.Signature)
 	if err != nil {
+		var takenErr roomdb.ErrAliasTaken
+		if errors.As(err, &takenErr) {
+			return nil, takenErr
+		}
 		return nil, fmt.Errorf("registerAlias: could not register alias: %w", err)
 	}
 

muxrpc/test/go/alias_test.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"crypto/rand"
 	"encoding/base64"
+	"errors"
 	"net/url"
 	"testing"
 	"time"
@@ -105,6 +106,14 @@ func TestAliasRegister(t *testing.T) {
 
 	t.Log("alias stored")
 
+	// check taken error
+	err = clientForServer.Async(ctx, &registerResponse, muxrpc.TypeString, muxrpc.Method{"room", "registerAlias"}, "bob", sig)
+	r.Error(err)
+
+	var callErr *muxrpc.CallError
+	r.True(errors.As(err, &callErr), "expected a call error: %T", err)
+	r.Equal(`alias ("bob") is already taken`, callErr.Message)
+
 	for _, bot := range theBots {
 		bot.srv.Shutdown()
 		r.NoError(bot.srv.Close())

roomdb/sqlite/aliases.go

@@ -7,6 +7,7 @@ import (
 	"database/sql"
 
 	"github.com/friendsofgo/errors"
+	"github.com/mattn/go-sqlite3"
 	"github.com/volatiletech/sqlboiler/v4/boil"
 	"github.com/volatiletech/sqlboiler/v4/queries/qm"
 
@@ -93,7 +94,10 @@ func (a Aliases) Register(ctx context.Context, alias string, userFeed refs.FeedR
 		newEntry.Signature = signature
 
 		err = newEntry.Insert(ctx, tx, boil.Infer())
-
+		var sqlErr sqlite3.Error
+		if errors.As(err, &sqlErr) && sqlErr.ExtendedCode == sqlite3.ErrConstraintUnique {
+			return roomdb.ErrAliasTaken{Name: alias}
+		}
 		return err
 	})
 }

roomdb/sqlite/aliases_test.go

@@ -71,7 +71,7 @@ func TestAliases(t *testing.T) {
 		err = db.Aliases.Register(ctx, testName, newMember, testSig)
 		r.NoError(err)
 
-		// should have one member now
+		// should have one alias now
 		lst, err := db.Aliases.List(ctx)
 		r.NoError(err)
 		r.Len(lst, 1)
@@ -97,3 +97,42 @@ func TestAliases(t *testing.T) {
 		r.EqualError(err, roomdb.ErrNotFound.Error())
 	})
 }
+
+func TestAliasesUniqueError(t *testing.T) {
+	r := require.New(t)
+	ctx := context.Background()
+
+	testRepo := filepath.Join("testrun", t.Name())
+	os.RemoveAll(testRepo)
+	tr := repo.New(testRepo)
+
+	db, err := Open(tr)
+	r.NoError(err)
+
+	// fake feed for testing, looks ok at least
+	newMember := refs.FeedRef{ID: bytes.Repeat([]byte("acab"), 8), Algo: refs.RefAlgoFeedSSB1}
+
+	// 64 bytes of random for testing (validation is handled by the handlers)
+	testSig := make([]byte, 64)
+	rand.Read(testSig)
+
+	testName := "thealias"
+
+	// allow the member
+	_, err = db.Members.Add(ctx, newMember, roomdb.RoleMember)
+	r.NoError(err)
+
+	err = db.Aliases.Register(ctx, testName, newMember, testSig)
+	r.NoError(err)
+
+	// should have one alias now
+	lst, err := db.Aliases.List(ctx)
+	r.NoError(err)
+	r.Len(lst, 1)
+
+	err = db.Aliases.Register(ctx, testName, newMember, testSig)
+	r.Error(err)
+	var takenErr roomdb.ErrAliasTaken
+	r.True(errors.As(err, &takenErr), "expected a special error value")
+	r.Equal(testName, takenErr.Name)
+}

roomdb/types.go

@@ -26,6 +26,14 @@ type Alias struct {
 	Signature []byte
 }
 
+type ErrAliasTaken struct {
+	Name string
+}
+
+func (e ErrAliasTaken) Error() string {
+	return fmt.Sprintf("alias (%q) is already taken", e.Name)
+}
+
 // Member holds all the information an internal user of the room has.
 type Member struct {
 	ID      int64