Create well-known path from oauth issuer (#2489)

* create well-known path from issuer

* pr feedback

auth/api/iam/metadata.go

@@ -18,7 +18,35 @@
 
 package iam
 
-import "net/url"
+import (
+	"github.com/nuts-foundation/nuts-node/core"
+	"net/url"
+)
+
+const (
+	// authzServerWellKnown is the well-known base path for the oauth authorization server metadata as defined in RFC8414
+	authzServerWellKnown = "/.well-known/oauth-authorization-server"
+	// openidCredIssuerWellKnown is the well-known base path for the openID credential issuer metadata as defined in OpenID4VCI specification
+	openidCredIssuerWellKnown = "/.well-known/openid-credential-issuer"
+	// openidCredWalletWellKnown is the well-known path element we created for openid4vci to retrieve the oauth client metadata
+	openidCredWalletWellKnown = "/.well-known/openid-credential-wallet"
+)
+
+// IssuerIdToWellKnown converts the OAuth2 Issuer identity to the specified well-known endpoint by inserting the well-known at the root of the path.
+// It returns no url and an error when issuer is not a valid URL.
+func IssuerIdToWellKnown(issuer string, wellKnown string, strictmode bool) (*url.URL, error) {
+	var issuerURL *url.URL
+	var err error
+	if strictmode {
+		issuerURL, err = core.ParsePublicURL(issuer, false, "https")
+	} else {
+		issuerURL, err = core.ParsePublicURL(issuer, true, "https", "http")
+	}
+	if err != nil {
+		return nil, err
+	}
+	return issuerURL.Parse(wellKnown + issuerURL.EscapedPath())
+}
 
 func authorizationServerMetadata(identity url.URL) OAuthAuthorizationServerMetadata {
 	return OAuthAuthorizationServerMetadata{

auth/api/iam/metadata_test.go

@@ -20,10 +20,50 @@ package iam
 
 import (
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"net/url"
 	"testing"
 )
 
+func TestIssuerIdToWellKnown(t *testing.T) {
+	t.Run("ok", func(t *testing.T) {
+		issuer := "https://nuts.nl/iam/id"
+		u, err := IssuerIdToWellKnown(issuer, authzServerWellKnown, true)
+		require.NoError(t, err)
+		assert.Equal(t, "https://nuts.nl/.well-known/oauth-authorization-server/iam/id", u.String())
+	})
+	t.Run("no path in issuer", func(t *testing.T) {
+		issuer := "https://nuts.nl"
+		u, err := IssuerIdToWellKnown(issuer, authzServerWellKnown, true)
+		require.NoError(t, err)
+		assert.Equal(t, "https://nuts.nl/.well-known/oauth-authorization-server", u.String())
+	})
+	t.Run("don't unescape path", func(t *testing.T) {
+		issuer := "https://nuts.nl/iam/%2E%2E/still-has-iam"
+		u, err := IssuerIdToWellKnown(issuer, authzServerWellKnown, true)
+		require.NoError(t, err)
+		assert.Equal(t, "https://nuts.nl/.well-known/oauth-authorization-server/iam/%2E%2E/still-has-iam", u.String())
+	})
+	t.Run("https in strictmode", func(t *testing.T) {
+		issuer := "http://nuts.nl/iam/id"
+		u, err := IssuerIdToWellKnown(issuer, authzServerWellKnown, true)
+		assert.ErrorContains(t, err, "scheme must be https")
+		assert.Nil(t, u)
+	})
+	t.Run("no IP allowed", func(t *testing.T) {
+		issuer := "http://127.0.0.1/iam/id"
+		u, err := IssuerIdToWellKnown(issuer, authzServerWellKnown, false)
+		assert.ErrorContains(t, err, "hostname is IP")
+		assert.Nil(t, u)
+	})
+	t.Run("invalid URL", func(t *testing.T) {
+		issuer := "http:// /iam/id"
+		u, err := IssuerIdToWellKnown(issuer, authzServerWellKnown, true)
+		assert.ErrorContains(t, err, "invalid character \" \" in host name")
+		assert.Nil(t, u)
+	})
+}
+
 func Test_authorizationServerMetadata(t *testing.T) {
 	identity := "https://example.com/iam/did:nuts:123"
 	identityURL, _ := url.Parse(identity)