refactor: move string generator to crypto package

internal/crypto/text.go

@@ -0,0 +1,16 @@
+package crypto
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+)
+
+// Text generates a cryptographically secure random string of a given length, and base64 URL-encodes it.
+func Text(length int) (string, error) {
+	data := make([]byte, length)
+	if _, err := rand.Read(data); err != nil {
+		return "", err
+	}
+
+	return base64.RawURLEncoding.EncodeToString(data), nil
+}

pkg/openid/client/login.go

@@ -16,7 +16,6 @@ import (
 	mw "github.com/nais/wonderwall/pkg/middleware"
 	"github.com/nais/wonderwall/pkg/openid"
 	"github.com/nais/wonderwall/pkg/openid/acr"
-	"github.com/nais/wonderwall/pkg/strings"
 	"github.com/nais/wonderwall/pkg/url"
 	log "github.com/sirupsen/logrus"
 	"go.opentelemetry.io/otel/attribute"
@@ -76,12 +75,12 @@ func (c *Client) newAuthorizationCodeParams(r *http.Request) (openid.Authorizati
 		return req, fmt.Errorf("generating callback url: %w", err)
 	}
 
-	nonce, err := strings.GenerateBase64(32)
+	nonce, err := crypto.Text(32)
 	if err != nil {
 		return req, fmt.Errorf("creating nonce: %w", err)
 	}
 
-	state, err := strings.GenerateBase64(32)
+	state, err := crypto.Text(32)
 	if err != nil {
 		return req, fmt.Errorf("creating state: %w", err)
 	}

pkg/openid/client/logout.go

@@ -8,7 +8,6 @@ import (
 	"github.com/nais/wonderwall/internal/crypto"
 	"github.com/nais/wonderwall/pkg/cookie"
 	"github.com/nais/wonderwall/pkg/openid"
-	"github.com/nais/wonderwall/pkg/strings"
 	urlpkg "github.com/nais/wonderwall/pkg/url"
 )
 
@@ -24,7 +23,7 @@ func NewLogout(c *Client, r *http.Request) (*Logout, error) {
 		return nil, fmt.Errorf("generating logout callback url: %w", err)
 	}
 
-	state, err := strings.GenerateBase64(32)
+	state, err := crypto.Text(32)
 	if err != nil {
 		return nil, fmt.Errorf("generating state: %w", err)
 	}

pkg/session/id.go

@@ -4,9 +4,9 @@ import (
 	"fmt"
 	"net/http"
 
+	"github.com/nais/wonderwall/internal/crypto"
 	"github.com/nais/wonderwall/pkg/openid"
 	openidconfig "github.com/nais/wonderwall/pkg/openid/config"
-	"github.com/nais/wonderwall/pkg/strings"
 )
 
 // ExternalID returns the external session ID, derived from the given request or id_token; e.g. `sid` or `session_state`.
@@ -33,7 +33,7 @@ func ExternalID(r *http.Request, cfg openidconfig.Provider, idToken *openid.IDTo
 	}
 
 	// 3. generate ID if all else fails
-	sessionID, err = strings.GenerateBase64(64)
+	sessionID, err = crypto.Text(64)
 	if err != nil {
 		return "", fmt.Errorf("generating session ID: %w", err)
 	}

pkg/strings/generator.go

@@ -1,29 +0,0 @@
-package strings
-
-import (
-	"crypto/rand"
-	"encoding/base64"
-	"fmt"
-	"io"
-)
-
-// GenerateBase64 generates a random string of a given length, and base64 URL-encodes it.
-func GenerateBase64(length int) (string, error) {
-	bytes, err := Generate(length)
-	if err != nil {
-		return "", err
-	}
-
-	return base64.RawURLEncoding.EncodeToString(bytes), nil
-}
-
-// Generate generates a random byte array of a given length.
-func Generate(length int) ([]byte, error) {
-	bytes := make([]byte, length)
-	_, err := io.ReadFull(rand.Reader, bytes)
-	if err != nil {
-		return nil, fmt.Errorf("reading rand.Reader: %w", err)
-	}
-
-	return bytes, nil
-}