SP: Add capability to provide intermediate certs (#178)

Author: BenJuan26

samlsp/samlsp.go

@@ -25,6 +25,7 @@ type Options struct {
 	Key               *rsa.PrivateKey
 	Logger            logger.Interface
 	Certificate       *x509.Certificate
+	Intermediates     []*x509.Certificate
 	AllowIDPInitiated bool
 	IDPMetadata       *saml.EntityDescriptor
 	IDPMetadataURL    *url.URL
@@ -57,6 +58,7 @@ func New(opts Options) (*Middleware, error) {
 			Key:               opts.Key,
 			Logger:            logr,
 			Certificate:       opts.Certificate,
+			Intermediates:     opts.Intermediates,
 			MetadataURL:       *metadataURL,
 			AcsURL:            *acsURL,
 			IDPMetadata:       opts.IDPMetadata,

service_provider.go

@@ -55,6 +55,7 @@ type ServiceProvider struct {
 
 	// Certificate is the RSA public part of Key.
 	Certificate *x509.Certificate
+	Intermediates []*x509.Certificate
 
 	// MetadataURL is the full URL to the metadata endpoint on this host,
 	// i.e. https://example.com/saml/metadata
@@ -112,6 +113,10 @@ func (sp *ServiceProvider) Metadata() *EntityDescriptor {
 	authnRequestsSigned := false
 	wantAssertionsSigned := true
 	validUntil := TimeNow().Add(validDuration)
+	certBytes := sp.Certificate.Raw
+	for _, intermediate := range sp.Intermediates {
+		certBytes = append(certBytes, intermediate.Raw...)
+	}
 	return &EntityDescriptor{
 		EntityID:   sp.MetadataURL.String(),
 		ValidUntil: validUntil,
@@ -125,13 +130,13 @@ func (sp *ServiceProvider) Metadata() *EntityDescriptor {
 							{
 								Use: "signing",
 								KeyInfo: KeyInfo{
-									Certificate: base64.StdEncoding.EncodeToString(sp.Certificate.Raw),
+									Certificate: base64.StdEncoding.EncodeToString(certBytes),
 								},
 							},
 							{
 								Use: "encryption",
 								KeyInfo: KeyInfo{
-									Certificate: base64.StdEncoding.EncodeToString(sp.Certificate.Raw),
+									Certificate: base64.StdEncoding.EncodeToString(certBytes),
 								},
 								EncryptionMethods: []EncryptionMethod{
 									{Algorithm: "http://www.w3.org/2001/04/xmlenc#aes128-cbc"},