Socket

1
Socket

• ??Win32 API

2
????????
3
???Socket

• ??????????????????????
• socket,?????????????,????
• ????????
• ???5???
• socket() ? ??
• bind() ? ??(?????)
• listen() ? ?????(????)
• connect() ? ?????
• accept() ? ????

4
Socket??,??????
5
socket ( )??

• int SOCKET socket(
• int af,
• int type,
• int protocol
• )
• af ??????(family),???????????
• type????
• Protocal??????
• ???-1????socket????
• ??????????,??socket descriptor
• (socket???)

6
????

• af ??AF_INET ? Internet address family
• ????????????
• unsigned long(?????)
• typeSOCK_STREAM ????????(TCP?)
• SOCK_DGRAM ???????(UDP?)
• protocal ??IPPROTO_TCP (TCP????)
  ???0,??????

7
??

• SOCKET sock //??
• sock socket( //??
• AF_INET,
• SOCK_STREAM,
• IPPROTO_TCP
• )

8
Bind??,???????
9
Bind()??

• int bind(
• SOCKET s,
• const struct sockaddr name,
• int namelen
• )
• s ????????socket
• name ???????,?????sockaddr
• namelen name?????(??byte)
• ???-1???,???0

10
Sockaddr_in ??(IPv4?)

• struct sockaddr_in short sin_family u_short
  sin_port
• struct in_addr sin_addr
• char sin_zero8
• sin_family??????,?????AF_INET
• sin_port????????? ?htons() ??
• sin_addr??IP?? in_addr????
• sin_zero8?????,??????

11
in_addr??

• typedef struct in_addr union
• struct u_char s_b1,s_b2,s_b3,s_b4
  S_un_b struct u_short s_w1,s_w2
  S_un_w u_long S_addr S_un
• in_addr
• ???union????,?????????32bit????
• ??????u_long S_addr???? ?IP????????
• ???????????????
• define s_addr S_un.s_addr
• ???????????sin_addr.s_addr????
• ?????inet_addr(IP????)???unsigned long

12
??

• SOCKET Sock
• sockaddr_in saServer
• Sock socket(
• AF_INET,
• SOCK_STREAM,
• IPPROTO_TCP
• )
• // ??????????
• saServer.sin_family AF_INET
• saServer.sin_port htons(5150) //??5150 port
• saServer.sin_addr.s_addr inet_addr(140.115.65.3
  0) //????IP
• // ??Bind??
• bind(Sock,(SOCKADDR) saServer, sizeof(saServer)
  )

13
Listen?? ??socket??????

• listen()??Socket????????,?????(Client)
  ????,????????????,?????????(Server)?
• ???Client?????,??????connect()??Server
  ????Server????????socket?Client??,listen
  socket?????????Client,???????

14
listen()??

• int listen(
• SOCKET s,
• int backlog
• )
• s???bind(),???????socket
• Backlog??Server?????,???????
• ???-1???,???0

15
Accept?? ??????
Blocking Non-blocking
16
Accept() ??

• SOCKET accept(
• SOCKET s,
• struct sockaddr addr,
• int addrlen
• )
• s?????listen???socket
• sddrClient?????,?????????
• addrlensddr??,???????
• ???-1????,?????????Client?????socket
  descriptor,???????
• ??accept()?listen socket?????????????,??????accep
  t()???????????Server?Client????socket,????????????
  ??

17
??

• ListenSocket ???bind()??????socket
• // ??socket????????
• if (listen( ListenSocket, 1 ) SOCKET_ERROR)
• printf("Error listening on socket.\n")
• // ???????Client????socket
• SOCKET AcceptSocket
• // ??????
• while(1)
• AcceptSocket SOCKET_ERROR
• //????socket descriptor,???????????
• while( AcceptSocket SOCKET_ERROR )
• AcceptSocket accept( ListenSocket, NULL,
  NULL )
• printf("Client connected.\n")
• break

18
connect?? ??????socket??

• Client????Server??,????connect????,???????????,??
  ???????
• ????(three-way handshake)??
• 1.Client?Server??????(connect())
• 2.Server?????,???Clinet????
• 3.Client????,?Server??????
• ??????????,??????????
• ?????,??????????ICMP????
• connect?????,????????

19
connect()??

• int connect(
• SOCKET s,
• const struct sockaddr name,
• int namelen
• )
• ???????bind()??
• name????
• ???-1???,????0

20
recv(),send()?? ??????

• ??????Server?Client??????,?????????????recv(),sen
  d()?????????,??????????????,read(),
• write(),readv(),writev(),recvmsg(),
• sendmsg()??,????recv()?send()?????,???????????MSD
  N? man ????

21
recv() ??

• int recv(
• SOCKET s,
• char buf,
• int len,
• int flags
• )
• s?????????socket
• buf??recv,????????????
• lenbuf???(byte)
• flags??????,????0
• ???-1???,????????????(byte)

22
send()??

• int send(
• SOCKET s,
• const char buf,
• int len,
• int flags
• )
• s?????????socket
• buf?????????????
• lenbuf???(byte)
• flags??????,????0
• ???-1???,???????????(byte)

23
??

• //Server?
• int bytesSent
• int bytesRecv SOCKET_ERROR
• char sendbuf32 "Server Sending Data."
• char recvbuf32 ""
• bytesRecv recv( m_socket, recvbuf, 32, 0 )
• printf( "Bytes Recv ld\n", bytesRecv )
• bytesSent send( m_socket, sendbuf,
  strlen(sendbuf), 0 )
• printf( "Bytes Sent ld\n", bytesSent )
• //Client?
• int bytesSent
• int bytesRecv SOCKET_ERROR
• char sendbuf32 "Client Sending data."
• char recvbuf32 ""
• bytesSent send( m_socket, sendbuf,
  strlen(sendbuf), 0 )
• printf( "Bytes Sent ld\n", bytesSent )

24
closesocket(),shutdown()?? ????

• ?accept()?connect()?????????socket,???Client?Serv
  er??closesocket()?shutdown()??????
• closesocket()??????TCP??,???????,?????socket?????
  ?????,??TCP???????sliding window??,?????????,?shut
  down()?????????????,????socket?IO?
• ??????????????
• 1.??????
• 2.??shutdown(),?????????
• 3.??recv(),??????????0,??????
• 4.closesocket() ???socket
• ??Winsock????closesocket()?BSD
  socket??close()????

25
closesocket() ? shutdown()??

• int closesocket(
• SOCKET s
• )
• int shutdown(
• SOCKET s,
• int how
• )
• s????socket
• how??socket?????
• SD_RECEIVE ????(disable recv()??)
• SD_SEND ????(disable send()??)
• SD_BOTH ????
• ???-1???,????0

26
Server-Client Model
recv() send()
27
WINSOCKETS

• include ltwinsock2.hgt

28
WINSOCKETS

• WSADATA wsadata
• if (WSAStartup(0x101,(LPWSADATA) wsadata) ! 0)
  
• fprintf(stderr,"echo_srv can't use WinSock
  DLL\n") exit(1)

29
WINSOCKETS

• WSACleanup()

30
Server??????

• ListBox ?????????? ListBox1-gtItems-gtAdd()?????
  ?ListBox1-gtItems-gtInsert()????Add(??),
  Insert(??,??)????Server?????????,??????

31
Server??????

• Timer ?????,????

32
Server??????

• define A B ??A?B,???define Add(Text)
  ListBox1-gtItems-gtInsert(0,Text)?????????Add(??)
  ????????Insert??
• ?define????????(???),?????????????

33
Server??????

• ????????????WSAStartupsocketbindlisten
• ?????????shutdownclosesocket

34
Server??????

• ?Timer?????????? recv???? ?? accept
  ????
• !accept recv ???????(?????????)?????????????

35
Server?????????

• 1. ???????WSAAcceptExWSARecvWaitForSingleObject
  
• 2. ????
• 3. ???