decode the amf0 command message: connect.

@@ -22,3 +22,69 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 */
 
 
 #include <srs_core_amf0.hpp>
 #include <srs_core_amf0.hpp>
+
+#include <srs_core_log.hpp>
+#include <srs_core_stream.hpp>
+
+// AMF0 marker
+#define RTMP_AMF0_Number 					0x00
+#define RTMP_AMF0_Boolean 					0x01
+#define RTMP_AMF0_String 					0x02
+#define RTMP_AMF0_Object 					0x03
+#define RTMP_AMF0_MovieClip 				0x04 // reserved, not supported
+#define RTMP_AMF0_Null 						0x05
+#define RTMP_AMF0_Undefined 				0x06
+#define RTMP_AMF0_Reference 				0x07
+#define RTMP_AMF0_EcmaArray 				0x08
+#define RTMP_AMF0_ObjectEnd 				0x09
+#define RTMP_AMF0_StrictArray 				0x0A
+#define RTMP_AMF0_Date 						0x0B
+#define RTMP_AMF0_LongString 				0x0C
+#define RTMP_AMF0_UnSupported 				0x0D
+#define RTMP_AMF0_RecordSet 				0x0E // reserved, not supported
+#define RTMP_AMF0_XmlDocument 				0x0F
+#define RTMP_AMF0_TypedObject 				0x10
+// AVM+ object is the AMF3 object.
+#define RTMP_AMF0_AVMplusObject 			0x11
+// origin array whos data takes the same form as LengthValueBytes
+#define RTMP_AMF0_OriginStrictArray 		0x20
+
+std::string srs_amf0_read_string(SrsStream* stream)
+{
+	std::string str;
+	
+	// marker
+	if (!stream->require(1)) {
+		return str;
+	}
+	
+	char marker = stream->read_char();
+	if (marker != RTMP_AMF0_String) {
+		return str;
+	}
+	
+	// len
+	if (!stream->require(2)) {
+		return str;
+	}
+	int16_t len = stream->read_2bytes();
+	
+	// data
+	if (!stream->require(len)) {
+		return str;
+	}
+	str = stream->read_string(len);
+	
+	// support utf8-1 only
+	// 1.3.1 Strings and UTF-8
+	// UTF8-1 = %x00-7F
+	for (int i = 0; i < len; i++) {
+		char ch = *(str.data() + i);
+		if ((ch & 0x80) != 0) {
+			srs_warn("only support utf8-1, 0x00-0x7F, actual is %#x", (int)ch);
+			return "";
+		}
+	}
+	
+	return str;
+}

@@ -30,4 +30,13 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 
 #include <srs_core.hpp>
 #include <srs_core.hpp>
 
 
+#include <string>
+
+class SrsStream;
+
+/**
+* read amf0 string from stream.
+*/
+extern std::string srs_amf0_read_string(SrsStream* stream);
+
 #endif
 #endif

@@ -62,6 +62,8 @@ int SrsBuffer::ensure_buffer_bytes(SrsSocket* skt, int required_size)
 {
 {
 	int ret = ERROR_SUCCESS;
 	int ret = ERROR_SUCCESS;
 
 
+	srs_assert(required_size >= 0);
+
 	while (size() < required_size) {
 	while (size() < required_size) {
 		char buffer[SOCKET_READ_SIZE];
 		char buffer[SOCKET_READ_SIZE];
 		
 		

@@ -52,6 +52,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #define ERROR_RTMP_PLAIN_REQUIRED		300
 #define ERROR_RTMP_PLAIN_REQUIRED		300
 #define ERROR_RTMP_CHUNK_START			301
 #define ERROR_RTMP_CHUNK_START			301
 #define ERROR_RTMP_MSG_INVLIAD_SIZE		302
 #define ERROR_RTMP_MSG_INVLIAD_SIZE		302
+#define ERROR_RTMP_AMF0_DECODE			303
 
 
 #define ERROR_SYSTEM_STREAM_INIT		400
 #define ERROR_SYSTEM_STREAM_INIT		400
 
 

@@ -24,9 +24,11 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <srs_core_protocol.hpp>
 #include <srs_core_protocol.hpp>
 
 
 #include <srs_core_log.hpp>
 #include <srs_core_log.hpp>
+#include <srs_core_amf0.hpp>
 #include <srs_core_error.hpp>
 #include <srs_core_error.hpp>
 #include <srs_core_socket.hpp>
 #include <srs_core_socket.hpp>
 #include <srs_core_buffer.hpp>
 #include <srs_core_buffer.hpp>
+#include <srs_core_stream.hpp>
 
 
 /**
 /**
 5. Protocol Control Messages
 5. Protocol Control Messages
@@ -37,12 +39,12 @@ reserved for usage with RTM Chunk Stream protocol. Protocol messages
 with IDs 3-6 are reserved for usage of RTMP. Protocol message with ID
 with IDs 3-6 are reserved for usage of RTMP. Protocol message with ID
 7 is used between edge server and origin server.
 7 is used between edge server and origin server.
 */
 */
-#define RTMP_MSG_SetChunkSize 0x01
-#define RTMP_MSG_AbortMessage 0x02
-#define RTMP_MSG_Acknowledgement 0x03
-#define RTMP_MSG_UserControlMessage 0x04
-#define RTMP_MSG_WindowAcknowledgementSize 0x05
-#define RTMP_MSG_SetPeerBandwidth 0x06
+#define RTMP_MSG_SetChunkSize 				0x01
+#define RTMP_MSG_AbortMessage 				0x02
+#define RTMP_MSG_Acknowledgement 			0x03
+#define RTMP_MSG_UserControlMessage 		0x04
+#define RTMP_MSG_WindowAcknowledgementSize 	0x05
+#define RTMP_MSG_SetPeerBandwidth 			0x06
 #define RTMP_MSG_EdgeAndOriginServerCommand 0x07
 #define RTMP_MSG_EdgeAndOriginServerCommand 0x07
 /**
 /**
 * The server sends this event to test whether the client is reachable. 
 * The server sends this event to test whether the client is reachable. 
@@ -50,14 +52,14 @@ with IDs 3-6 are reserved for usage of RTMP. Protocol message with ID
 * Event data is a 4-byte timestamp, representing the local server time when the server dispatched the command. 
 * Event data is a 4-byte timestamp, representing the local server time when the server dispatched the command. 
 * The client responds with PingResponse on receiving PingRequest.
 * The client responds with PingResponse on receiving PingRequest.
 */
 */
-#define RTMP_MSG_PCUC_PingRequest 0x06
+#define RTMP_MSG_PCUC_PingRequest 			0x06
 
 
 /**
 /**
 * The client sends this event to the server in response to the ping request. 
 * The client sends this event to the server in response to the ping request. 
 * 
 * 
 * The event data is a 4-byte timestamp, which was received with the PingRequest request.
 * The event data is a 4-byte timestamp, which was received with the PingRequest request.
 */
 */
-#define RTMP_MSG_PCUC_PingResponse 0x07
+#define RTMP_MSG_PCUC_PingResponse 			0x07
 /**
 /**
 3. Types of messages
 3. Types of messages
 The server and the client send messages over the network to
 The server and the client send messages over the network to
@@ -77,8 +79,8 @@ contains related parameters. A client or a server can request Remote
 Procedure Calls (RPC) over streams that are communicated using the
 Procedure Calls (RPC) over streams that are communicated using the
 command messages to the peer.
 command messages to the peer.
 */
 */
-#define RTMP_MSG_AMF3CommandMessage 17 // 0x11
-#define RTMP_MSG_AMF0CommandMessage 20 // 0x14
+#define RTMP_MSG_AMF3CommandMessage 		17 // 0x11
+#define RTMP_MSG_AMF0CommandMessage 		20 // 0x14
 /**
 /**
 3.2. Data message
 3.2. Data message
 The client or the server sends this message to send Metadata or any
 The client or the server sends this message to send Metadata or any
@@ -87,8 +89,8 @@ data(audio, video etc.) like creation time, duration, theme and so
 on. These messages have been assigned message type value of 18 for
 on. These messages have been assigned message type value of 18 for
 AMF0 and message type value of 15 for AMF3.        
 AMF0 and message type value of 15 for AMF3.        
 */
 */
-#define RTMP_MSG_AMF0DataMessage 18 // 0x12
-#define RTMP_MSG_AMF3DataMessage 15 // 0x0F
+#define RTMP_MSG_AMF0DataMessage 			18 // 0x12
+#define RTMP_MSG_AMF3DataMessage 			15 // 0x0F
 /**
 /**
 3.3. Shared object message
 3.3. Shared object message
 A shared object is a Flash object (a collection of name value pairs)
 A shared object is a Flash object (a collection of name value pairs)
@@ -97,14 +99,14 @@ so on. The message types kMsgContainer=19 for AMF0 and
 kMsgContainerEx=16 for AMF3 are reserved for shared object events.
 kMsgContainerEx=16 for AMF3 are reserved for shared object events.
 Each message can contain multiple events.
 Each message can contain multiple events.
 */
 */
-#define RTMP_MSG_AMF3SharedObject 16 // 0x10
-#define RTMP_MSG_AMF0SharedObject 19 // 0x13
+#define RTMP_MSG_AMF3SharedObject 			16 // 0x10
+#define RTMP_MSG_AMF0SharedObject 			19 // 0x13
 /**
 /**
 3.4. Audio message
 3.4. Audio message
 The client or the server sends this message to send audio data to the
 The client or the server sends this message to send audio data to the
 peer. The message type value of 8 is reserved for audio messages.
 peer. The message type value of 8 is reserved for audio messages.
 */
 */
-#define RTMP_MSG_AudioMessage 8 // 0x08
+#define RTMP_MSG_AudioMessage 				8 // 0x08
 /* *
 /* *
 3.5. Video message
 3.5. Video message
 The client or the server sends this message to send video data to the
 The client or the server sends this message to send video data to the
@@ -113,14 +115,14 @@ These messages are large and can delay the sending of other type of
 messages. To avoid such a situation, the video message is assigned
 messages. To avoid such a situation, the video message is assigned
 the lowest priority.
 the lowest priority.
 */
 */
-#define RTMP_MSG_VideoMessage 9 // 0x09
+#define RTMP_MSG_VideoMessage 				9 // 0x09
 /**
 /**
 3.6. Aggregate message
 3.6. Aggregate message
 An aggregate message is a single message that contains a list of submessages.
 An aggregate message is a single message that contains a list of submessages.
 The message type value of 22 is reserved for aggregate
 The message type value of 22 is reserved for aggregate
 messages.
 messages.
 */
 */
-#define RTMP_MSG_AggregateMessage 22 // 0x16
+#define RTMP_MSG_AggregateMessage 			22 // 0x16
 
 
 /**
 /**
 * 6.1.2. Chunk Message Header
 * 6.1.2. Chunk Message Header
@@ -131,21 +133,21 @@ messages.
 // Chunks of Type 0 are 11 bytes long. This type MUST be used at the
 // Chunks of Type 0 are 11 bytes long. This type MUST be used at the
 // start of a chunk stream, and whenever the stream timestamp goes
 // start of a chunk stream, and whenever the stream timestamp goes
 // backward (e.g., because of a backward seek).
 // backward (e.g., because of a backward seek).
-#define RTMP_FMT_TYPE0 0
+#define RTMP_FMT_TYPE0 						0
 // 6.1.2.2. Type 1
 // 6.1.2.2. Type 1
 // Chunks of Type 1 are 7 bytes long. The message stream ID is not
 // Chunks of Type 1 are 7 bytes long. The message stream ID is not
 // included; this chunk takes the same stream ID as the preceding chunk.
 // included; this chunk takes the same stream ID as the preceding chunk.
 // Streams with variable-sized messages (for example, many video
 // Streams with variable-sized messages (for example, many video
 // formats) SHOULD use this format for the first chunk of each new
 // formats) SHOULD use this format for the first chunk of each new
 // message after the first.
 // message after the first.
-#define RTMP_FMT_TYPE1 1
+#define RTMP_FMT_TYPE1 						1
 // 6.1.2.3. Type 2
 // 6.1.2.3. Type 2
 // Chunks of Type 2 are 3 bytes long. Neither the stream ID nor the
 // Chunks of Type 2 are 3 bytes long. Neither the stream ID nor the
 // message length is included; this chunk has the same stream ID and
 // message length is included; this chunk has the same stream ID and
 // message length as the preceding chunk. Streams with constant-sized
 // message length as the preceding chunk. Streams with constant-sized
 // messages (for example, some audio and data formats) SHOULD use this
 // messages (for example, some audio and data formats) SHOULD use this
 // format for the first chunk of each message after the first.
 // format for the first chunk of each message after the first.
-#define RTMP_FMT_TYPE2 2
+#define RTMP_FMT_TYPE2 						2
 // 6.1.2.4. Type 3
 // 6.1.2.4. Type 3
 // Chunks of Type 3 have no header. Stream ID, message length and
 // Chunks of Type 3 have no header. Stream ID, message length and
 // timestamp delta are not present; chunks of this type take values from
 // timestamp delta are not present; chunks of this type take values from
@@ -160,7 +162,7 @@ messages.
 // need for a chunk of type 2 to register the delta. If Type 3 chunk
 // need for a chunk of type 2 to register the delta. If Type 3 chunk
 // follows a Type 0 chunk, then timestamp delta for this Type 3 chunk is
 // follows a Type 0 chunk, then timestamp delta for this Type 3 chunk is
 // the same as the timestamp of Type 0 chunk.
 // the same as the timestamp of Type 0 chunk.
-#define RTMP_FMT_TYPE3 3
+#define RTMP_FMT_TYPE3 						3
 
 
 /**
 /**
 * 6. Chunking
 * 6. Chunking
@@ -172,7 +174,7 @@ messages.
 * good for high-bit rate streaming. Chunk size is maintained
 * good for high-bit rate streaming. Chunk size is maintained
 * independently for each direction.
 * independently for each direction.
 */
 */
-#define RTMP_DEFAULT_CHUNK_SIZE 128
+#define RTMP_DEFAULT_CHUNK_SIZE 			128
 
 
 /**
 /**
 * 6.1. Chunk Format
 * 6.1. Chunk Format
@@ -185,7 +187,12 @@ messages.
 * the normal timestamp field MUST NOT be used and MUST be set to
 * the normal timestamp field MUST NOT be used and MUST be set to
 * 0xffffff and the extended timestamp MUST be sent.
 * 0xffffff and the extended timestamp MUST be sent.
 */
 */
-#define RTMP_EXTENDED_TIMESTAMP 0xFFFFFF
+#define RTMP_EXTENDED_TIMESTAMP 			0xFFFFFF
+
+/**
+* amf0 command message, command name: "connect"
+*/
+#define RTMP_AMF0_COMMAND_CONNECT			"connect"
 
 
 SrsMessageHeader::SrsMessageHeader()
 SrsMessageHeader::SrsMessageHeader()
 {
 {
@@ -218,6 +225,7 @@ SrsChunkStream::~SrsChunkStream()
 SrsMessage::SrsMessage()
 SrsMessage::SrsMessage()
 {
 {
 	size = 0;
 	size = 0;
+	stream = NULL;
 	payload = NULL;
 	payload = NULL;
 	decoded_payload = NULL;
 	decoded_payload = NULL;
 }
 }
@@ -233,6 +241,11 @@ SrsMessage::~SrsMessage()
 		delete decoded_payload;
 		delete decoded_payload;
 		decoded_payload = NULL;
 		decoded_payload = NULL;
 	}
 	}
+	
+	if (stream) {
+		delete stream;
+		stream = NULL;
+	}
 }
 }
 
 
 SrsPacket* SrsMessage::get_packet()
 SrsPacket* SrsMessage::get_packet()
@@ -249,7 +262,44 @@ int SrsMessage::decode_packet()
 {
 {
 	int ret = ERROR_SUCCESS;
 	int ret = ERROR_SUCCESS;
 	
 	
-	// TODO: decode packet.
+	srs_assert(payload != NULL);
+	srs_assert(size > 0);
+	
+	if (!stream) {
+		srs_verbose("create decode stream for message.");
+		stream = new SrsStream();
+	}
+	
+	if (header.message_type == RTMP_MSG_AMF0CommandMessage) {
+		srs_verbose("start to decode AMF0 command message.");
+		
+		// amf0 command message.
+		// need to read the command name.
+		if ((ret = stream->initialize((char*)payload, size)) != ERROR_SUCCESS) {
+			srs_error("initialize stream failed. ret=%d", ret);
+			return ret;
+		}
+		srs_verbose("decode stream initialized success");
+		
+		std::string command = srs_amf0_read_string(stream);
+		srs_verbose("AMF0 command message, command_name=%s", command.c_str());
+		
+		stream->reset();
+		if (command == RTMP_AMF0_COMMAND_CONNECT) {
+			srs_info("decode the AMF0 command(connect vhost/app message).");
+			decoded_payload = new SrsConnectAppPacket();
+			return decoded_payload->decode(stream);
+		}
+		
+		// default packet to drop message.
+		srs_trace("drop the AMF0 command message, command_name=%s", command.c_str());
+		decoded_payload = new SrsPacket();
+		return ret;
+	}
+	
+	// default packet to drop message.
+	srs_trace("drop the unknown message, type=%d", header.message_type);
+	decoded_payload = new SrsPacket();
 	
 	
 	return ret;
 	return ret;
 }
 }
@@ -262,6 +312,12 @@ SrsPacket::~SrsPacket()
 {
 {
 }
 }
 
 
+int SrsPacket::decode(SrsStream* /*stream*/)
+{
+	int ret = ERROR_SUCCESS;
+	return ret;
+}
+
 SrsConnectAppPacket::SrsConnectAppPacket()
 SrsConnectAppPacket::SrsConnectAppPacket()
 {
 {
 }
 }
@@ -270,6 +326,24 @@ SrsConnectAppPacket::~SrsConnectAppPacket()
 {
 {
 }
 }
 
 
+int SrsConnectAppPacket::decode(SrsStream* stream)
+{
+	int ret = ERROR_SUCCESS;
+	
+	if ((ret = super::decode(stream)) != ERROR_SUCCESS) {
+		return ret;
+	}
+
+	command_name = srs_amf0_read_string(stream);
+	if (command_name.empty()) {
+		ret = ERROR_RTMP_AMF0_DECODE;
+		srs_error("amf0 decode connect command_name failed. ret=%d", ret);
+		return ret;
+	}
+	
+	return ret;
+}
+
 SrsProtocol::SrsProtocol(st_netfd_t client_stfd)
 SrsProtocol::SrsProtocol(st_netfd_t client_stfd)
 {
 {
 	stfd = client_stfd;
 	stfd = client_stfd;
@@ -317,12 +391,21 @@ int SrsProtocol::recv_message(SrsMessage** pmsg)
 			srs_error("recv interlaced message failed. ret=%d", ret);
 			srs_error("recv interlaced message failed. ret=%d", ret);
 			return ret;
 			return ret;
 		}
 		}
+		srs_verbose("entire msg received");
 		
 		
 		if (!msg) {
 		if (!msg) {
 			continue;
 			continue;
 		}
 		}
 		
 		
-		// return the msg with raw/undecoded payload
+		if (msg->size <= 0 || msg->header.payload_length <= 0) {
+			srs_trace("ignore empty message(type=%d, size=%d, time=%d, sid=%d).",
+				msg->header.message_type, msg->header.payload_length,
+				msg->header.timestamp, msg->header.stream_id);
+			delete msg;
+			continue;
+		}
+		
+		srs_verbose("get a msg with raw/undecoded payload");
 		*pmsg = msg;
 		*pmsg = msg;
 		break;
 		break;
 	}
 	}
@@ -598,9 +681,12 @@ int SrsProtocol::read_message_payload(SrsChunkStream* chunk, int bh_size, int mh
 		// need erase the header in buffer.
 		// need erase the header in buffer.
 		buffer->erase(bh_size + mh_size);
 		buffer->erase(bh_size + mh_size);
 		
 		
-		srs_warn("get an empty RTMP "
+		srs_trace("get an empty RTMP "
 				"message(type=%d, size=%d, time=%d, sid=%d)", chunk->header.message_type, 
 				"message(type=%d, size=%d, time=%d, sid=%d)", chunk->header.message_type, 
 				chunk->header.payload_length, chunk->header.timestamp, chunk->header.stream_id);
 				chunk->header.payload_length, chunk->header.timestamp, chunk->header.stream_id);
+		
+		*pmsg = chunk->msg;
+		chunk->msg = NULL;
 				
 				
 		return ret;
 		return ret;
 	}
 	}

@@ -31,6 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <srs_core.hpp>
 #include <srs_core.hpp>
 
 
 #include <map>
 #include <map>
+#include <string>
 
 
 #include <st.h>
 #include <st.h>
 
 
@@ -40,6 +41,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 class SrsSocket;
 class SrsSocket;
 class SrsBuffer;
 class SrsBuffer;
 class SrsPacket;
 class SrsPacket;
+class SrsStream;
 class SrsMessage;
 class SrsMessage;
 class SrsChunkStream;
 class SrsChunkStream;
 
 
@@ -127,6 +129,7 @@ public:
 	int8_t* payload;
 	int8_t* payload;
 // decoded message payload.
 // decoded message payload.
 private:
 private:
+	SrsStream* stream;
 	SrsPacket* decoded_payload;
 	SrsPacket* decoded_payload;
 public:
 public:
 	/**
 	/**
@@ -150,13 +153,21 @@ class SrsPacket
 public:
 public:
 	SrsPacket();
 	SrsPacket();
 	virtual ~SrsPacket();
 	virtual ~SrsPacket();
+public:
+	virtual int decode(SrsStream* stream);
 };
 };
 
 
 class SrsConnectAppPacket : public SrsPacket
 class SrsConnectAppPacket : public SrsPacket
 {
 {
+private:
+	typedef SrsPacket super;
+private:
+	std::string command_name;
 public:
 public:
 	SrsConnectAppPacket();
 	SrsConnectAppPacket();
 	virtual ~SrsConnectAppPacket();
 	virtual ~SrsConnectAppPacket();
+public:
+	virtual int decode(SrsStream* stream);
 };
 };
 
 
 /**
 /**

@@ -28,7 +28,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 
 SrsStream::SrsStream()
 SrsStream::SrsStream()
 {
 {
-	bytes = NULL;
+	p = bytes = NULL;
 	size = 0;
 	size = 0;
 }
 }
 
 
@@ -53,8 +53,54 @@ int SrsStream::initialize(char* _bytes, int _size)
 	}
 	}
 
 
 	size = _size;
 	size = _size;
-	bytes = _bytes;
+	p = bytes = _bytes;
 
 
 	return ret;
 	return ret;
 }
 }
 
 
+void SrsStream::reset()
+{
+	p = bytes;
+}
+
+bool SrsStream::empty()
+{
+	return !p || !bytes || (p >= bytes + size);
+}
+
+bool SrsStream::require(int required_size)
+{
+	return !empty() && (required_size < bytes + size - p);
+}
+
+char SrsStream::read_char()
+{
+	srs_assert(require(1));
+	
+	return *p++;
+}
+
+int16_t SrsStream::read_2bytes()
+{
+	srs_assert(require(2));
+	
+	int16_t value;
+	pp = (char*)&value;
+	pp[1] = *p++;
+	pp[0] = *p++;
+	
+	return value;
+}
+
+std::string SrsStream::read_string(int len)
+{
+	srs_assert(require(len));
+	
+	std::string value;
+	value.append(p, len);
+	
+	p += len;
+	
+	return value;
+}
+

@@ -30,9 +30,14 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 
 #include <srs_core.hpp>
 #include <srs_core.hpp>
 
 
+#include <sys/types.h>
+#include <string>
+
 class SrsStream
 class SrsStream
 {
 {
 protected:
 protected:
+	char* p;
+	char* pp;
 	char* bytes;
 	char* bytes;
 	int size;
 	int size;
 public:
 public:
@@ -46,6 +51,24 @@ public:
 	* @remark, stream never free the _bytes, user must free it.
 	* @remark, stream never free the _bytes, user must free it.
 	*/
 	*/
 	virtual int initialize(char* _bytes, int _size);
 	virtual int initialize(char* _bytes, int _size);
+	/**
+	* reset the position to beginning.
+	*/
+	virtual void reset();
+	/**
+	* whether stream is empty.
+	* if empty, never read or write.
+	*/
+	virtual bool empty();
+	/**
+	* whether required size is ok.
+	* @return true if stream can read/write specified required_size bytes.
+	*/
+	virtual bool require(int required_size);
+public:
+	virtual char read_char();
+	virtual int16_t read_2bytes();
+	virtual std::string read_string(int len);
 };
 };
 
 
 #endif
 #endif