三、流程图和数据类型定义
1.流程图
A．总流程图
包总长度：nPacketLength已解码长度：reportLength开始解码Ethernet II解码Internet Protocolox84IP头的Protocol字段0x060x11ox2fSCTPTCPUDPGRE读取SCTP_HEADERWhile(nPacketLength >reportLength)NOYES结束解码SCTP Body解码M3UA、SCCP、RANAP B. Stream Control Transmission Protocol流程图
包总长度：nPacketLength已解码长度：reportLength开始读取SCTP_HEADERNOWhile(nPacketLength >reportLength)YES读取SCTPCHUNKTYPEYESYESSCTP_DATA_CHUNKSCTP_SACK_CHUNKPayload Protocol IdentifierYES M3UA解码M3UANO M3UA跳过SCTP_SACK_CHUNK
C. MTP 3 User Adaptation Layer流程图
M3UA_HEADER中的MessageClass类型MGMT: Management Messages TM: Transfer Messages SSNM: SS7 Signalling Network Management MessagesASPSM: ASP State Maintenance MessagesASPTM: ASP Traffic Maintenance Messages RKM: Routing Key Management Messages开始M3UA_TAG_PARAMETER：M3UA_NETWORK_APPEARANCM3UA_ROUTING_CONTEXTM3UA_PROTOCOL_DATAM3UA_CORRELATION_ID读取M3UA_HEADERLEN = M3UA_MAX_PADING_LENGTHMGMTTMSSNMASPSMASPTMRKMM3UA_TM_TYPEIS PAYLOADDATANOT PAYLOADDATAWhile（RemainLength> LEN）YES解码M3UA_TAG_PARAMETER当M3UA_TAG_PARAMETER为M3UA_PROTOCOL_DATA时解码SCCP数据NO结束 D. Signalling Connection Control Part流程图
SCCP_PARAMETER_NAME:SCCP_MESSAGE_TYPE:CONNECTION_REQUEST（CR）CONNECTION_CONFIRM（CC)CONNECTION_REFUSED（CREF）RELEASED （RLSD）RELEASE_COMPLETE （RLC）DATA_FORM1 （DT1)END_OF_OPTIONAL_PARAMETERS DESTINATION_LOCAL_REFERENCESOURCE_LOCAL_REFERENCECALLED_PARTY_ADDRESS CALLING_PARTY_ADDRESS PROTOCOL_CLASS SEGMENTING_REASSEMBLING RECEIVE_SEQUENCE_NUMBER SEQUENCING_SEGMENTING CREDIT RELEASE_CAUSE RETURN_CAUSE RESET_CAUSE ERROR_CAUSE REFUSAL_CAUSE SCCP_DATA SEGMENTATION HOP_COUNTER IMPORTANCE DT1LONG_DATA 开始读取SCCP_MESSAGE_TYPECRCCCREFRLSDRLC读取SCCP_CONNECTION_CONFIRM_HEADER读取SCCP_CONNECTION_CONFIRM_HEADER读取SCCP_CONNECTION_REFUSED_HEADER解码可选择参数读取SCCP_RELEASED_HEADER读取SCCP_RELEASE_COMPLETE_HEADER读取SCCP_DATA_FORM1_HEADER解码长度可变参数解码可选择参数解码可选择参数解码长度可变参数参数名为SCCP_DATA 时解码可选择参数参数名为SCCP_DATA 时参数名为SCCP_DATA 时参数名为SCCP_DATA 时参数名为SCCP_DATA 时解码RANAP数据解码RANAP数据解码RANAP数据解码RANAP数据解码RANAP数据结束
2.数据类型定义
A. Stream Control Transmission Protocol SCTP_HEADER
字段 srcPort dstPort tagVerification checksum 长度（字节） 2 2 4 4
SCTPCHUNKTYPE
SCTP Chunk Type DATA INIT INIT_ACK SACK HEARTBEAT HEARTBEAT_ACK ABORT SHUTDOWN SHUTDOWN_ACK ERROR COOKIE_ECHO COOKIE_ACK ECNE CWR SHUTDOWN_COMPLETE
Value 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Description Payload Data Initiation Initiation Acknowledgement Selective Acknowledgement Heartbeat Request Heartbeat Acknowledgement Abort Shutdown Shutdown Acknowledgement Operation Error State Cookie Cookie Acknowledgement Reserved for Explicit Congestion Notification Echo Reserved for Congestion Window Reduced Shutdown Complete SCTP_DATA_CHUNK
字段 ChunkType ChunkFlag ChunkLength 长度（字节） 1 1 2