Add a payload.get_header_length() method, remove header length definitions

src/libcharon/encoding/payloads/cert_payload.c

@@ -173,6 +173,12 @@ METHOD(payload_t, get_encoding_rules, int,
 	return countof(encodings);
 }
 
+METHOD(payload_t, get_header_length, int,
+	private_cert_payload_t *this)
+{
+	return 5;
+}
+
 METHOD(payload_t, get_type, payload_type_t,
 	private_cert_payload_t *this)
 {
@@ -270,6 +276,7 @@ cert_payload_t *cert_payload_create()
 			.payload_interface = {
 				.verify = _verify,
 				.get_encoding_rules = _get_encoding_rules,
+				.get_header_length = _get_header_length,
 				.get_length = _get_length,
 				.get_next_type = _get_next_type,
 				.set_next_type = _set_next_type,
@@ -283,7 +290,7 @@ cert_payload_t *cert_payload_create()
 			.destroy = _destroy,
 		},
 		.next_payload = NO_PAYLOAD,
-		.payload_length = CERT_PAYLOAD_HEADER_LENGTH,
+		.payload_length = get_header_length(this),
 	);
 	return &this->public;
 }
@@ -312,7 +319,7 @@ cert_payload_t *cert_payload_create_from_cert(certificate_t *cert)
 		free(this);
 		return NULL;
 	}
-	this->payload_length = CERT_PAYLOAD_HEADER_LENGTH + this->data.len;
+	this->payload_length = get_header_length(this) + this->data.len;
 	return &this->public;
 }
 
@@ -325,7 +332,7 @@ cert_payload_t *cert_payload_create_from_hash_and_url(chunk_t hash, char *url)
 
 	this->encoding = ENC_X509_HASH_AND_URL;
 	this->data = chunk_cat("cc", hash, chunk_create(url, strlen(url)));
-	this->payload_length = CERT_PAYLOAD_HEADER_LENGTH + this->data.len;
+	this->payload_length = get_header_length(this) + this->data.len;
 	return &this->public;
 }
 
@@ -338,6 +345,6 @@ cert_payload_t *cert_payload_create_custom(cert_encoding_t type, chunk_t data)
 
 	this->encoding = type;
 	this->data = data;
-	this->payload_length = CERT_PAYLOAD_HEADER_LENGTH + this->data.len;
+	this->payload_length = get_header_length(this) + this->data.len;
 	return &this->public;
 }