[extension/oidcauth] Fix case-sensitivity of authorization header

.chloggen/oicdauth-fix-case-auth-header.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: oidcauthextension
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix case-sensitivity of authorization header
+
+# One or more tracking issues related to the change
+issues: [18405]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

extension/oidcauthextension/extension.go

@@ -90,7 +90,8 @@ func (e *oidcExtension) start(context.Context, component.Host) error {
 
 // authenticate checks whether the given context contains valid auth data. Successfully authenticated calls will always return a nil error and a context with the auth data.
 func (e *oidcExtension) authenticate(ctx context.Context, headers map[string][]string) (context.Context, error) {
-	authHeaders := headers[e.cfg.Attribute]
+	metadata := client.NewMetadata(headers)
+	authHeaders := metadata.Get(e.cfg.Attribute)
 	if len(authHeaders) == 0 {
 		return ctx, errNotAuthenticated
 	}

extension/oidcauthextension/extension_test.go

@@ -71,6 +71,13 @@ func TestOIDCAuthenticationSucceeded(t *testing.T) {
 	assert.NoError(t, err)
 	assert.NotNil(t, ctx)
 
+	// test, upper-case header
+	ctx, err = p.Authenticate(context.Background(), map[string][]string{"Authorization": {fmt.Sprintf("Bearer %s", token)}})
+
+	// verify
+	assert.NoError(t, err)
+	assert.NotNil(t, ctx)
+
 	// TODO(jpkroehling): assert that the authentication routine set the subject/membership to the resource
 }