From 62817ed054888963dd92693c104ea1e6291864b0 Mon Sep 17 00:00:00 2001
From: Wout Slakhorst <wout.slakhorst@nedap.com>
Date: Tue, 28 Nov 2023 13:42:55 +0100
Subject: [PATCH] reduce duplicate code

---
 auth/api/iam/openid4vp.go | 42 +++++++++++++--------------------------
 1 file changed, 14 insertions(+), 28 deletions(-)

diff --git a/auth/api/iam/openid4vp.go b/auth/api/iam/openid4vp.go
index 7475264763..c112b62d40 100644
--- a/auth/api/iam/openid4vp.go
+++ b/auth/api/iam/openid4vp.go
@@ -54,33 +54,21 @@ func (r *Wrapper) handleAuthorizeRequestFromHolder(ctx context.Context, verifier
 	// GET authorization server metadata for wallet
 	walletID, ok := params[clientIDParam]
 	if !ok {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.InvalidRequest,
-			Description: "missing client_id parameter",
-		}
+		return nil, oauthError(oauth.InvalidRequest, "missing client_id parameter")
 	}
 	// the walletDID must be a did:web
 	walletDID, err := did.ParseDID(walletID)
 	if err != nil || walletDID.Method != "web" {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.InvalidRequest,
-			Description: "invalid client_id parameter",
-		}
+		return nil, oauthError(oauth.InvalidRequest, "invalid client_id parameter")
 	}
 	metadata, err := r.auth.RelyingParty().AuthorizationServerMetadata(ctx, *walletDID)
 	if err != nil {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.ServerError,
-			Description: "failed to get authorization server metadata (holder)",
-		}
+		return nil, oauthError(oauth.ServerError, "failed to get authorization server metadata (holder)")
 	}
 	// own generic endpoint
 	ownURL, err := didweb.DIDToURL(verifier)
 	if err != nil {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.ServerError,
-			Description: "failed to translate own did to URL",
-		}
+		return nil, oauthError(oauth.ServerError, "failed to translate own did to URL")
 	}
 	// generate presentation_definition_uri based on own presentation_definition endpoint + scope
 	pdURL := ownURL.JoinPath("presentation_definition")
@@ -99,19 +87,13 @@ func (r *Wrapper) handleAuthorizeRequestFromHolder(ctx context.Context, verifier
 	//    &nonce=n-0S6_WzA2Mj HTTP/1.1
 	walletURL, err := url.Parse(metadata.AuthorizationEndpoint)
 	if err != nil || len(metadata.AuthorizationEndpoint) == 0 {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.InvalidRequest,
-			Description: "invalid authorization_endpoint (holder)",
-		}
+		return nil, oauthError(oauth.InvalidRequest, "invalid authorization_endpoint (holder)")
 	}
 	nonce := crypto.GenerateNonce()
 	callbackURL := ownURL
 	callbackURL.Path, err = url.JoinPath(callbackURL.Path, "response")
 	if err != nil {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.ServerError,
-			Description: "failed to construct redirect path",
-		}
+		return nil, oauthError(oauth.ServerError, "failed to construct redirect path")
 	}
 
 	redirectURL := AddQueryParams(*walletURL, map[string]string{
@@ -131,10 +113,7 @@ func (r *Wrapper) handleAuthorizeRequestFromHolder(ctx context.Context, verifier
 	}
 	// use nonce to store authorization request in session store
 	if err = r.storageEngine.GetSessionDatabase().GetStore(sessionExpiry, openID4VCContext, verifier.String(), sessionStoreType).Put(nonce, openid4vpRequest); err != nil {
-		return nil, oauth.OAuth2Error{
-			Code:        oauth.ServerError,
-			Description: "failed to store client state",
-		}
+		return nil, oauthError(oauth.ServerError, "failed to store client state")
 	}
 
 	return HandleAuthorizeRequest302Response{
@@ -381,3 +360,10 @@ func assertParamNotPresent(params map[string]string, param ...string) error {
 	}
 	return nil
 }
+
+func oauthError(code oauth.ErrorCode, description string) oauth.OAuth2Error {
+	return oauth.OAuth2Error{
+		Code:        code,
+		Description: description,
+	}
+}