recoverysigner: make allowed-source-account optional (#5052)

What
This PR makes the --allowed-source-account flag optional.

Why
When ALLOWED_SOURCE_ACCOUNT is not specified or is empty, strings.Split(opts.AllowedSourceAccounts, ",") will return a slice containing an empty string. And we will get an error at keypair.ParseAddress(addressStr).

exp/services/recoverysigner/internal/serve/serve.go

@@ -145,12 +145,14 @@ func getHandlerDeps(opts Options) (handlerDeps, error) {
 	}
 
 	allowedSourceAccounts := []*keypair.FromAddress{}
-	for _, addressStr := range strings.Split(opts.AllowedSourceAccounts, ",") {
-		accountAddress, err := keypair.ParseAddress(addressStr)
-		if err != nil {
-			return handlerDeps{}, errors.Wrap(err, "parsing allowed source accounts")
+	if opts.AllowedSourceAccounts != "" {
+		for _, addressStr := range strings.Split(opts.AllowedSourceAccounts, ",") {
+			accountAddress, err := keypair.ParseAddress(addressStr)
+			if err != nil {
+				return handlerDeps{}, errors.Wrap(err, "parsing allowed source accounts")
+			}
+			allowedSourceAccounts = append(allowedSourceAccounts, accountAddress)
 		}
-		allowedSourceAccounts = append(allowedSourceAccounts, accountAddress)
 	}
 
 	deps := handlerDeps{

exp/services/recoverysigner/internal/serve/serve_test.go

@@ -0,0 +1,35 @@
+package serve
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stellar/go/keypair"
+	supportlog "github.com/stellar/go/support/log"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gopkg.in/square/go-jose.v2"
+)
+
+func TestGetHandlerDeps(t *testing.T) {
+	signingKey := "SBWLXUTJR2CGVPGCZDIGGLQDPX7ZGGBHBFXBJ555MNIQ2PZCCLM643Z3"
+	signingKeyFull := keypair.MustParseFull(signingKey)
+
+	opts := Options{
+		Logger:      supportlog.DefaultLogger,
+		SigningKeys: signingKey,
+		SEP10JWKS:   `{"keys":[{"kty":"EC","crv":"P-256","alg":"ES256","x":"i8chX_7Slm4VQ_Y6XBWVBnxIO5-XSWH1GJsXWNkal3E","y":"G22r0OgrcQnkfCAqsS6wvtHgR0SbfvXNJy6-jJfvc94"}]}`,
+	}
+
+	sep10JWKS := jose.JSONWebKeySet{}
+	err := json.Unmarshal([]byte(opts.SEP10JWKS), &sep10JWKS)
+	require.NoError(t, err)
+
+	got, err := getHandlerDeps(opts)
+	assert.NoError(t, err)
+
+	assert.Equal(t, []*keypair.Full{signingKeyFull}, got.SigningKeys)
+	assert.Equal(t, []*keypair.FromAddress{signingKeyFull.FromAddress()}, got.SigningAddresses)
+	assert.Equal(t, sep10JWKS, got.SEP10JWKS)
+	assert.Equal(t, []*keypair.FromAddress{}, got.AllowedSourceAccounts)
+}