最近在看udt協(xié)議的一些知識，先把包結(jié)構(gòu)放上來

UDT包結(jié)構(gòu)

總體結(jié)構(gòu)：

0               1               2               3               

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 

Packet Header(包頭)

Data/Control Information Field(數(shù)據(jù)包/控制包 信息)

數(shù)據(jù)包包頭結(jié)構(gòu)：

0               1               2               3               

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 

0 |                           Sequence Number

ff  |o |                       Message Number

Time Stamp

Destination Socket ID

bit 0:

0: Data Packet(0：數(shù)據(jù)包)

1: Control Packet（1：控制包）

bit ff:

11: solo message packet（11：單一的消息包）

10: first packet of a message（10：一份消息的第一個包）

01: last packet of a message（00：一份消息的最后一個包）

bit o:

0: in order delivery not required（0：沒有要求按正常序號傳遞）

1: in order delivery required（1：要求按正常序號傳遞）

控制包包頭結(jié)構(gòu)：

0               1               2               3               

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 

1 |       Type             |       Reserved

Additional Info

Time Stamp

Destination Socket ID

bit 0:

0: Data Packet(0：數(shù)據(jù)包)

1: Control Packet（1：控制包）

bit 1~15:

       0: Protocol Connection Handshake

Add. Info:    Undefined

Control Info: Handshake information (see CHandShake)

1: Keep-alive

Add. Info:    Undefined

Control Info: None

2: Acknowledgement (ACK)

Add. Info:    The ACK sequence number

Control Info: The sequence number to which (but not include) all the previous packets have beed received

Optional:     RTT

RTT Variance

advertised flow window size (number of packets)

estimated bandwidth (number of packets per second)

3: Negative Acknowledgement (NAK)

Add. Info:    Undefined

Control Info: Loss list (see loss list coding below)

4: Congestion Warning

Add. Info:    Undefined

Control Info: None

5: Shutdown

Add. Info:    Undefined

Control Info: None

6: Acknowledgement of Acknowledement (ACK-square)

Add. Info:    The ACK sequence number

Control Info: None

7: Message Drop Request

Add. Info:    Message ID

Control Info: first sequence number of the message

last seqeunce number of the message

     65535: Explained by bits 16 - 31

bit 16 - 31:

This space is used for future expansion or user defined control packets.