Add support for a new big-endian handshake format

Because of strange dicisions in the past, fastd currently uses little endian
type and length values in its handshake. As the common network byte order is
big endian, changing the handshake format would be preferable.

This commit adds support for a new big-endian handshake. For now, fastd will
continue to send little-endian handshakes so ensure backwarts compatiblity, but
if it receives a big-endian handshake, it will respond with a big-endian one.

1 files changed, 43 insertions, 22 deletions

diff --git a/src/handshake.h b/src/handshake.h
index 760d21b..f5582e9 100644
--- a/src/handshake.h
+++ b/src/handshake.h
@@ -89,11 +89,18 @@ struct fastd_handshake {
 	fastd_handshake_record_t records[RECORD_MAX]; /**< The TLV records of the handshake */
 	uint16_t tlv_len;		/**< The length of the TLV record data */
 	void *tlv_data;			/**< TLV record data */
+	bool little_endian;		/**< true if the old little-endian handshake format is used */
+};
+
+/** A buffer a handshake to send is prepared in */
+struct fastd_handshake_buffer {
+	fastd_buffer_t buffer;
+	bool little_endian;
 };
 
 
-fastd_buffer_t fastd_handshake_new_init(size_t tail_space);
-fastd_buffer_t fastd_handshake_new_reply(uint8_t type, const fastd_method_info_t *method, bool with_method_list, size_t tail_space);
+fastd_handshake_buffer_t fastd_handshake_new_init(size_t tail_space);
+fastd_handshake_buffer_t fastd_handshake_new_reply(uint8_t type, bool little_endian, const fastd_method_info_t *method, bool with_method_list, size_t tail_space);
 
 void fastd_handshake_handle(fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, fastd_buffer_t buffer);
 
@@ -111,34 +118,42 @@ static inline uint16_t fastd_handshake_tlv_len(const fastd_buffer_t *buffer) {
 }
 
 /** Adds an uninitialized TLV record of given type and length to a handshake buffer */
-static inline uint8_t * fastd_handshake_extend(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, size_t len) {
-	uint8_t *dst = buffer->data + buffer->len;
+static inline uint8_t * fastd_handshake_extend(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, size_t len) {
+	uint8_t *dst = buffer->buffer.data + buffer->buffer.len;
 
-	if (buffer->data + buffer->len + 4 + len > buffer->base + buffer->base_len)
+	if (buffer->buffer.data + buffer->buffer.len + 4 + len > buffer->buffer.base + buffer->buffer.base_len)
 		exit_bug("not enough buffer allocated for handshake");
 
-	buffer->len += 4 + len;
+	buffer->buffer.len += 4 + len;
 
-	fastd_handshake_packet_t *packet = buffer->data;
-	packet->tlv_len = htons(fastd_handshake_tlv_len(buffer) + 4 + len);
+	fastd_handshake_packet_t *packet = buffer->buffer.data;
+	packet->tlv_len = htons(fastd_handshake_tlv_len(&buffer->buffer) + 4 + len);
 
-	dst[0] = type;
-	dst[1] = type >> 8;
-	dst[2] = len;
-	dst[3] = len >> 8;
+	if (buffer->little_endian) {
+		dst[0] = type;
+		dst[1] = type >> 8;
+		dst[2] = len;
+		dst[3] = len >> 8;
+	}
+	else {
+		dst[0] = type >> 8;
+		dst[1] = type;
+		dst[2] = len >> 8;
+		dst[3] = len;
+	}
 
 	return dst+4;
 }
 
 /** Adds an TLV record of given type and length initialized with arbitraty data to a handshake buffer */
-static inline void fastd_handshake_add(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, size_t len, const void *data) {
+static inline void fastd_handshake_add(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, size_t len, const void *data) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, len);
 
 	memcpy(dst, data, len);
 }
 
 /** Adds an TLV record of given type and length initialized with zeros to a handshake buffer */
-static inline uint8_t * fastd_handshake_add_zero(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, size_t len) {
+static inline uint8_t * fastd_handshake_add_zero(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, size_t len) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, len);
 
 	memset(dst, 0, len);
@@ -146,14 +161,14 @@ static inline uint8_t * fastd_handshake_add_zero(fastd_buffer_t *buffer, fastd_h
 }
 
 /** Adds an uint8 TLV record of given type and value to a handshake buffer */
-static inline void fastd_handshake_add_uint8(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, uint8_t value) {
+static inline void fastd_handshake_add_uint8(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, uint8_t value) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, 1);
 
 	dst[0] = value;
 }
 
 /** Adds an uint16 TLV record of given type and value to a handshake buffer */
-static inline void fastd_handshake_add_uint16(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, uint16_t value) {
+static inline void fastd_handshake_add_uint16(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, uint16_t value) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, 2);
 
 	dst[0] = value >> 8;
@@ -161,7 +176,7 @@ static inline void fastd_handshake_add_uint16(fastd_buffer_t *buffer, fastd_hand
 }
 
 /** Adds an uint24 TLV record of given type and value to a handshake buffer */
-static inline void fastd_handshake_add_uint24(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, uint32_t value) {
+static inline void fastd_handshake_add_uint24(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, uint32_t value) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, 3);
 
 	dst[0] = value >> 16;
@@ -170,7 +185,7 @@ static inline void fastd_handshake_add_uint24(fastd_buffer_t *buffer, fastd_hand
 }
 
 /** Adds an uint32 TLV record of given type and value to a handshake buffer */
-static inline void fastd_handshake_add_uint32(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, uint32_t value) {
+static inline void fastd_handshake_add_uint32(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, uint32_t value) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, 4);
 
 	dst[0] = value >> 24;
@@ -180,15 +195,21 @@ static inline void fastd_handshake_add_uint32(fastd_buffer_t *buffer, fastd_hand
 }
 
 /** Adds an uint16 TLV record of given type and value to a handshake buffer encoded as little endian */
-static inline void fastd_handshake_add_uint16_le(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, uint16_t value) {
+static inline void fastd_handshake_add_uint16_endian(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, uint16_t value) {
 	uint8_t *dst = fastd_handshake_extend(buffer, type, 2);
 
-	dst[0] = value;
-	dst[1] = value >> 8;
+	if (buffer->little_endian) {
+		dst[0] = value;
+		dst[1] = value >> 8;
+	}
+	else {
+		dst[0] = value >> 8;
+		dst[1] = value;
+	}
 }
 
 /** Adds an TLV record of given type and value to a handshake buffer, automatically using a 1- to 4-byte value */
-static inline void fastd_handshake_add_uint(fastd_buffer_t *buffer, fastd_handshake_record_type_t type, uint32_t value) {
+static inline void fastd_handshake_add_uint(fastd_handshake_buffer_t *buffer, fastd_handshake_record_type_t type, uint32_t value) {
 	if (value > 0xffffff)
 		fastd_handshake_add_uint32(buffer, type, value);
 	if (value > 0xffff)