Cleanup and fixes (#3273)

* newRequestID() (previously generateUploadID()) returns string than byte array.
* Remove unclear comments and added appropriate comments.
* SHA-256, MD5 Hash functions return Hex/Base64 encoded string than byte array.
* Remove duplicate MD5 hasher functions.
* Rename listObjectsValidateArgs() into validateListObjectsArgs()
* Remove repeated auth check code in all bucket request handlers.
* Remove abbreviated names in bucket-metadata
* Avoid nested if in bucketPolicyMatchStatement()
* Use ioutil.ReadFile() instead of os.Open() and ioutil.ReadAll()
* Set crossDomainXML as constant.

cmd/certs.go

@@ -114,14 +114,7 @@ func isSSL() bool {
 
 // Reads certificated file and returns a list of parsed certificates.
 func readCertificateChain() ([]*x509.Certificate, error) {
-	file, err := os.Open(mustGetCertFile())
-	if err != nil {
-		return nil, err
-	}
-	defer file.Close()
-
-	// Read the cert successfully.
-	bytes, err := ioutil.ReadAll(file)
+	bytes, err := ioutil.ReadFile(mustGetCertFile())
 	if err != nil {
 		return nil, err
 	}