Ensure certificate has a non-nil config when caching (fixes #875)

Also we change the scheme of the site's address if TLS is enabled and
no other scheme is explicitly set; this makes it appear as "https" when
we print it; otherwise it would show "http" when TLS is turned on
implicitly, and that is confusing/incorrect.

caddytls/certificates.go

@@ -205,6 +205,9 @@ func makeCertificate(certPEMBlock, keyPEMBlock []byte) (Certificate, error) {
 //
 // This function is safe for concurrent use.
 func cacheCertificate(cert Certificate) {
+	if cert.Config == nil {
+		cert.Config = new(Config)
+	}
 	certCacheMu.Lock()
 	if _, ok := certCache[""]; !ok {
 		// use as default - must be *appended* to list, or bad things happen!

caddytls/config.go

@@ -17,7 +17,7 @@ type Config struct {
 	// The hostname or class of hostnames this config is
 	// designated for; can contain wildcard characters
 	// according to RFC 6125 §6.4.3 - this field MUST
-	// NOT be empty in order for things to work smoothly
+	// be set in order for things to work as expected
 	Hostname string
 
 	// Whether TLS is enabled