Unix Network Programming, 2nd Ed., W. Richard Stevens, Prentice Hall PTR, 1999.

1
???? ?????

• Unix Network Programming, 2nd Ed., W. Richard
  Stevens, Prentice Hall PTR, 1999.
• ??? ? Unix Network Programming, Stevens ?, ???,
  ??? ?, ???, 1991.
• ??????? ?????, ???, ???, ???????, 2000.

2
10.7 ??

• ????? ?? ??? ?? ??
• ????? ?? ?? ??
• ??? ?? ???? ??? ?????-?? ??(client-server model)?
  ??
• ??
• ? ??? ???? ??? ?? ???? ???
• ? ???? ?? ??? ??? ??

3
?????? ??? ??
Transport
?? ?? ?? ??
4
??? ??? ??

• ??? ??(connection oriented protocol
  TCP(Transmission Control Protocol)

5
???? ?? ??? ??

• Server(connectionless protocol UDP(User
  Datagram Protocol))
• 
  
• 
  
  
  
  
• 
  
  Client
• blocks until data
• received from a client
• 
  data(request)
• 
  
• process request
• 
  
• 
  data(reply)

socket()
bind()
recvfrom()
socket()
bind()
sendto()
write()
read()
6
10.7 ??

• ?? ????

7
10.7 ??

• ?? ??? ??
• ??? ??? ?? ??
• ???(domain)
• ??? ????? ??? ???? ??? ??
• ??(type)
• ?????? ?? ??? ??? ? ?? ??? ??? ??
• ????(protocol)
• ?? ??? ???? ??? ??? ??
• ??? ??? ????? ??? ???? ??? ??
• AF Address Family
• AF_UNIX
• ?????? ??? ??? ??? ???? ?
• AF_INET
• ?????? ??? ???? ?? ????? ??? ? ??
• AF_NS
• ?????? ??? XEROX ???? ???? ??? ? ??

8
10.7 ??

• ?? ?????? ???? ??? ?? ??
• SOCK_STREAM
• ?? ??? ??, ???, ??? ??? ??? ???? ?? ??? ???
• SOCK_DGRAM
• ??? ???, ???, ???? ?? ??? ???
• SOCK_SEQPACKET
• ????? ??, ???, ??? ??? ??? ???? ?? ?? ??
• SOCK_RAW
• ?? ???? ????? ?????? ?? ?? ??

9
10.7 ??

• ???? ?? ???? ?? ??? ????? ??
• Yes? ??? ??? ?? ??? ???,
• ? ??? ???? ?? ????.

??
10
10.7 ??

• ?? ???? ??
• ?? ??? ??? ?? ??
• /usr/include/sys/types.h
• /usr/include/sys/socket.h ??
• ?? ???? ?? ???? ??
• ?? ???? P525

11
10.7 ??

• ??
• ??? ??? ????, ??? ?????
• ??? ???? ?? ???? ????
• ??? ???? ?????? ??

12
10.7 ??

• ??? ?? socket( )
• socket( )? ???? ?? ??
• ??
• ??? domain, type, protocol? ???? ?? ??? ??
• ?? ?? ??? ?? ??? ??? ??? ?? ??? (serverFd)? ??
• ?? ?? ??? ?? ??? (serverFd)? -1 ??

13
10.7 ??

• ??? ?? ?? bind( )
• ??? ???? ?? ?? ???, bind( )? ???? ?? ??
• ??? 0? ??, ??? -1? ??
• ??
• address? ??? ?? ??? ??? ?? ??? fd? ???? ?? ???
  ????
• addressLen? ?? ???? ??? ??
• ??? ??? ??? ?? ?? ???? ??

14
10.7 ??

• ???? ?? ??? ??
• AF_UNIX ???
• sockaddr_un ???? ??
• AF_INET ???
• sockaddr_in ???? ??

15
10.7 ??

• ?? ? ?? listen( )
• ?? ?? ?? ??? ?? ?? ??
• ??, ?????? ?? ? ?? ?? ??? ????? ???, ? ??? ???
• ??
• ?) listen (serverFd, 5) /?? ?? ??? ?? ?? /

16
10.7 ??

• ????? ?? accept( )
• ?????? ?? ?? ??
• ???? ????, ????? -1 ??
• accept( )? ?? ? ??? ??? ? ?? ??? ??
• ??
• address ??? ?????? ??, ?? ??? ??? ?????? ??
• addressLen address? ??? ???? ???? ??? ???? ??

17
10.7 ??

• ?????
• ???? ?? ??? ????, ??? ??? ??? ??????? ??? ????
  ????
• ??? ???? ?????? ??

18
10.7 ??

• ???? connect( )
• ??? ??? ??
• connect( ) ??? 0????, ?? ??? ?? ?? ???, ?? ??
  ??? ??? -1??
• ??
• address ????? ??? ???? ?? ????? ??? ??
• ?? ???, fd? ??? ??? ???? ?? ??
• addressLen? ?? ???? ??? ??

19
10.7 ??

• ???? ?? IP ??? PORT ??? ?? ??
• 32bit IP ??? 16bit port ?? ??
• ???? ?? ??
• s? ?? ???? ??
• ??? ?? A.B.C.D ??? IP ??? ??
• ? ?????? ??? 32bit? IP ??? ??
• ??? ?? ??? ??? ???? ??
• ? ?????? ?? 32bit IP ??? ??
• Inettime ?? ???? p536 p538 (debugging)

20
Chef.c

• include ltstdio.hgt
• include ltsignal.hgt
• include ltsys/types.hgt
• include ltsys/socket.hgt
• include ltsys/un.hgt / AF_UNIX ??? /
• define DEFAULT_PROTOCOL 0
• main()
• int serverFd, clientFd, serverLen, clientLen
• struct sockaddr_un serverUNIXAddress / ??
  ?? /
• struct sockaddr_un clientUNIXAddress /
  ????? ?? /
• struct sockaddr serverSockAddrPtr / ??
  ??? ?? ??? /
• struct sockaddr clientSockAddrPtr /
  ????? ??? ?? ??? /
• / ??? ???? ?? ??-?? ???? ?? /
• signal(SIGCHLD, SIG_IGN)

21
Chef.c (cont)

• / ???, ??? ????? ??? ?? ?? /
• serverFd socket(AF_UNIX, SOCK_STREAM,
  DEFAULT_PROTOCOL)
• serverUNIXAddress.sun_family AF_UNIX /
  ??? ?? ?? /
• strcpy (serverUNIXAddress.sun_path, "recipe")
  / ?? ??/
• unlink( "recipe") / ?? ?? ???, ?? ?? /
• bind(serverFd, serverSockAddrPtr, serverLen)
  / ?? ?? /
• listen(serverFd, 5) / ???? ??? ?? ?? /
• while(1) / ???? /
• / ????? ?? ?? /
• clientFd accept(serverFd,
  clientSockAddrPtr, clientLen)
• printf(" Server called! ")
• if (fork() 0) / ???? ??? ?? ?? /
• writeRecipe(clientFd) / ??? ?? /
• close(clientFd) / ?? ?? /

22
Cook.c

• include ltstdio.hgt
• include ltsignal.hgt
• include ltsys/types.hgt
• include ltsys/socket.hgt
• include ltsys/un.hgt
• define DEFAULT_PROTOCOL 0
• main()
• int clientFd, serverLen, result
• struct sockaddr_un serverUNIXAddress
• struct sockaddr serverSockAddrPtr
• serverSockAddrPtr (struct sockaddr)
  serverUNIXAddress
• serverLen sizeof(serverUNIXAddress)
• / ???, ??? ???????? ???? /

23
Cook.c (cont)

• readRecipe(clientFd) / ??? ?? /
• close(clientFd) / ?? ?? /
• exit(/ EXIT_SUCCESS / 0) / ?? ?/
• readRecipe(int fd)
• char str200
• while(readLine(fd, str)) / ?? ??? ? ?? /
• printf("s\n", str) / ?????? ? ?? /
• //
• readLine(int fd, char str)
• int n
• do
• n read(fd,str,1)

24
inettime.c ???? ????

• include ltstdio.hgt
• include ltsignal.hgt
• include ltctype.hgt
• include ltsys/types.hgt
• include ltsys/socket.hgt
• include ltnetinet/in.hgt / For
  AFINET sockets /
• include ltarpa/inet.hgt
• include ltnetdb.hgt
• define DAYTIME_PORT 13 /
  Standard port o /
• define DEFAULT_PROTOCOL 0
• unsigned long promptForINETAddress ()
• unsigned long nameToAddr ()
• main ()
• int clientFd / Client socket file descriptor
  /
• int serverLen / Length of server address
  structure /
• int result / From connect () call /
• struct sockaddr_in serverINETAddress / Server
  address /
• struct sockaddr serverSockAddrPtr / Pointer
  to address /

25
inettime.c ???? ????(cont.)

• serverLen sizeof (serverINETAddress) / Length
  of address /
• while (1) / Loop until break /
• inetAddress promptForINETAddress () /
  Get 32-bit IP /
• if (inetAddress 0) break / Done /
• / Start by zeroing out the entire address
  structure /
• bzero ((char)serverINETAddress,sizeof(serv
  erINETAddress))
• serverINETAddress.sin_family AF_INET /
  Use Internet /
• serverINETAddress.sin_addr.s_addr
  inetAddress / IP /
• serverINETAddress.sin_port htons
  (DAYTIME_PORT)
• / Now create the client socket /
• clientFd socket (AF_INET, SOCK_STREAM,
  DEFAULT_PROTOCOL)
• do / Loop until a connection is made with
  the server /
• result connect (clientFd,serverSockAdd
  rPtr,serverLen)
• if (result -1) sleep (1) / Try
  again in 1 second /
• while (result -1)
• readTime (clientFd) / Read the time from
  the server /

26
inettime.c ???? ????(cont.)

• unsigned long promptForINETAddress ()
• char hostName 100 / Name from user numeric
  or symbolic /
• unsigned long inetAddress / 32-bit IP format
  /
• / Loop until quit or a legal name is entered
  /
• / If quit, return 0 else return host's IP
  address /
• do
• printf ("Host name (q quit, s self)
  ")
• scanf ("s", hostName) / Get name from
  keyboard /
• if (strcmp (hostName, "q") 0) return
  (0) / Quit /
• inetAddress nameToAddr (hostName) /
  Convert to IP /
• if (inetAddress 0) printf ("Host name
  not found\n")
• while (inetAddress 0)
• unsigned long nameToAddr (name)
• char name

27
inettime.c ???? ????(cont.)

• if (strcmp (name, "s") 0) / Get host name
  from database /
• gethostname (hostName,100)
• printf ("Self host name is s\n",
  hostName)
• else / Assume name is a valid symbolic host
  name /
• strcpy (hostName, name)
• / Now obtain address information from
  database /
• hostStruct gethostbyname (hostName)
• if (hostStruct NULL) return (0) / Not
  Found /
• / Extract the IP Address from the hostent
  structure /
• hostNode (struct in_addr)
  hostStruct-gth_addr
• / Display a readable version for fun /
• printf ("Internet Address s\n", inet_ntoa
  (hostNode))
• return (hostNode-gts_addr) / Return IP
  address /
• readTime (fd)
• int fd

28
inettime.c ???? ????(cont.)

• readLine (fd, str)
• int fd
• char str
• / Read a single NEWLINE-terminated line /
• int n
• do / Read characters until NULL or
  end-of-input /
• n read (fd, str, 1) / Read one
  character /
• while (n gt 0 str ! '\n')
• return (n gt 0) / Return false if
  end-of-input /

29
10.7 ??

• ???? ?????
• ?? ??? AF_INET
• ?? ?? ???(sockaddr_in)? 4??
• sin_family ??? ?????, AF_INET? ??
• sin_port ?? ?? ??
• sin_addr ?????/??? 32bit IP ??
• sin_zero ????, ????? ???
• ???? ??
• ?? ?? ???? ??? ????? ??? ??
• sin_port ??? INADDR_ANY? ??, ??? ??? ?? ?????
  ???? ?????? ?? ??
• struct sockaddr_in serverINETAddress / ??
  ???? ?? /
• serverINETAddress.sin_family AF_INET / ????
  ???/
• serverINETAddress.sin_addr.s_addr
  htonl(INADDR_ANY)
• / ?? ????/
• serverINETAddress.sin_port htons(port) /??
  ?? ??/

30
10.7 ??
31
10.7 ??
32
10.7 ??

• ???? ??
• ?? ?? ???? ??? ????? ??? ??
• sin_port ??? INADDR_ANY? ??, ??? ??? ?? ?????
  ???? ?????? ?? ??
• struct sockaddr_in serverINETAddress / ??
  ???? ?? /
• serverINETAddress.sin_family AF_INET / ????
  ???/
• serverINETAddress.sin_addr.s_addr
  htonl(INADDR_ANY)
• / ?? ????/
• serverINETAddress.sin_port htons(port) /??
  ?? ??/

33
IP????? ??? ?? ? ?? ??

• Media.inchon.ac.kr
  192.203.144.1
• ??? ?? IP ??(binary)
  dotted decimal
• gethostbyname( )
  inet_addr( )
• gethostbyaddr( )
  inet_ntoa( )

11000011 11001011 10010000 00001011
34
?????? ?????(????)

• ??? ???
  ?? ?? ?? ???
• 
  
• 
  (??)
• ?? ??? ?? 3
• ????? 4
  (??)
• 5
  (??)

35
??????? ??,TCP/IP? ??

• ??? ??? ????
  ???
• 
  
• 
  ?? ????
• 
  (????)
• 
  ??
• 
  (????)
• 
  ????? ??
• 
  ??? ??
• 
  (IP??)
• 
  ????
• fd File Descriptor IPInternet Protocol
  sdSocket Descriptor
• TCPTransmission Control Protocol UDPUser
  Datagram Protocol

??1
??2
??3
??4
fd3
sd4
sd3
sd3
sd3




3000 3001
3002
3003 TCP/IP
211.119.245.149
UDP
TCP
I P
36
?? ??

• / Definitions for UNIX IPC domain
  /usr/include/sys/un.h /
• struct sockaddr_un
• sa_family_t sun_family
  / AF_UNIX /
• char sun_path108
  / path name (gag) /
• / Socket address, internet style
  /usr/include/netinet/in.h /
• struct sockaddr_in
• sa_family_t sin_family
• in_port_t sin_port
• struct in_addr sin_addr

37
?? ??

• / Internet address /usr/include/netinet/in.h
• This definition contains obsolete fields
  for compatibility
• with SunOS 3.x and 4.2bsd. The presence
  of subnets renders
• divisions into fixed fields misleading at
  best. New code
• should use only the s_addr field. /
• if !defined(_XPG4_2) defined(__EXTENSIONS__)
• define _S_un_b S_un_b
• define _S_un_w S_un_w
• define _S_addr S_addr
• define _S_un S_un
• endif / !defined(_XPG4_2) defined(__EXTENSION
  S__) /
• struct in_addr
• union
• struct uchar_t s_b1, s_b2,
  s_b3, s_b4 _S_un_b
• struct ushort_t s_w1, s_w2
  _S_un_w
• if !defined(_XPG4_2) defined(__EXTENSIONS__)
• uint32_t _S_addr
• else

38
?? ??(Port Number)

• 16-?? ?? ??
• ?? ??? ????? ???? TCP? UDP? ??? ? ?? ?? ? ???
  ????? ??? ??? ?? ??
• 32-?? Internet ???? ???? ?? ??, ?? ???? ???? ??
  ??
• 1255 ?? ??? ?? ??
• /usr/include/netinet/in.h ?? ?? ??(well-known
  ports) ??
• (?) FTP ?? TCP/IP ?? ?? 21
• 4.3BSD 11023 ???? ???? ?? ??
• 1023 lt TCP? ?? ?? lt 5000
• ??? ??(TCP/IP ?? UDP/IP)?? ??? ???? 5?
• ??(TCP ?? UDP)
• ?? ???? Internet ??(32-??)
• ?? ?? ??(16-??)
• ?? ???? Internet ??(32-??)
• ?? ?? ??(16-??)
• (?) tcp, 128.10.0.3, 1500, 128.10.0.7, 21

39
inetserver.c ???? ??

• / compile gcc -o client client.c -lsocket
  -lnsl /
• / execute server /
• include ltstdio.hgt
• include ltsys/types.hgt
• include ltsys/socket.hgt
• include ltnetinet/in.hgt
• include ltarpa/inet.hgt
• include ltnetdb.hgt
• define PORTNUM 3000
• main(int argc, char argv)
• int serverFd, clientFd, clilen, childpid
• struct sockaddr_in cli_addr, serv_addr
• if((serverFd socket(AF_INET, SOCK_STREAM,
  0)) lt 0)
• printf("server can't open stream socket")
• return -1
• bzero((char ) serv_addr, sizeof(serv_addr))
• serv_addr.sin_family AF_INET

40
inetserver.c ???? ??(cont.)

• for( )
• / Wait for a connection from a client
  process.
• This is an example of a concurrent
  server. /
• clilen sizeof(cli_addr)
• clientFd accept(serverFd, (struct
  sockaddr ) cli_addr, clilen)
• printf("Server called\n")
• if((childpid fork()) lt 0)
• printf("server fork error")
• exit(0)
• else if(childpid 0) / child
  process /
• printf("serverFd d, clientFd d\n",
  serverFd, clientFd)
• /
  process the request /
• write(clientFd,"Hello!",7)
  
• close(clientFd) / close
  original socket /
• return -1
• close(clientFd) / parent
  process /

41
inetclient.c ???? ?????

• / compile gcc -o client client.c -lsocket
  -lnsl /
• / execute inetclient hostname(or server IP)
  /
• include ltstdio.hgt
• include ltsys/types.hgt
• include ltsys/socket.hgt
• include ltnetinet/in.hgt
• include ltarpa/inet.hgt
• include ltnetdb.hgt
• define PORTNUM 3000
• main(int argc, char argv)
• int clientFd
• char str10
• char hostaddress
• struct sockaddr_in serv_addr
• struct hostent hostStruct
• struct in_addr hostNode
• if(argv1 NULL)
• printf("Usage inetclient hostname(or
  server IP)\n")

42
inetclient.c ???? ?????(cont.)

• hostStruct gethostbyname(argv1)
• if(hostStruct NULL) return(0)
• hostNode (struct in_addr)
  hostStruct-gth_addr
• hostaddress inet_ntoa(hostNode)
• / Fill in the structure "serv_addr" with the
  address of the
• server that we want to connect with. /
• bzero((char ) serv_addr, sizeof(serv_addr))
• serv_addr.sin_family AF_INET
• serv_addr.sin_addr.s_addr inet_addr(hostaddre
  ss)
• serv_addr.sin_port htons(PORTNUM)
• /Open a TCP socket (an Internet stream
  soskcet). /
• if((clientFd socket(AF_INET, SOCK_STREAM,
  0)) lt 0)
• printf("client can't open stream socket")
• / Connect to the server /
• if(connect(clientFd, (struct sockaddr )
  serv_addr, sizeof(serv_addr)) lt 0)
• printf("client can't connect to server")
• printf("clientFd d\n", clientFd)
• read(clientFd, str, 10)
• printf("s\n", str)

43
10.8 ???? ?

• ??
• ???? ?? ?? ?? ??
• ?? ??? ?? ?????, ????-??? ?? ??
• ?? ??? ??? ??? ???? ?? ??
• ?? ??(token)? ??(tab ?? space)? ??? ??
• ?? ?? ??? ???? ??

44
10.8 ???? ?

• ?? ?? ?? ??? ?? ??? ??? ??

ltinternetshellcommandgt ltsequencegt
ltsequencegt ltpipelinegt ltpipelinegt
ltpipelinegt ltsimplegt ltsimplegt ltsimplegt
lttokengt ltredirectiongt ltredirectiongt
ltfileRedirectiongt ltsocketRedirectiongt
ltfileRedirectiongt \gt ltfilegt gtgt ltfilegt \lt
ltfilegt ltsocketRedirectiongt ltclientRedirectiongt
ltserverRedirectiongt ltclientRedirectiongt
_at_\gtc ltsocketgt _at_\ltc ltsocketgt ltserverRedirectiongt
_at_\gts ltsocketgt _at_\lts ltsocketgt lttokengt a
string of chracters ltfilegt a valid UNIX
pathname ltsocketgt either a UNIX pathname (
UNIX domain socket ) or an Internet socket
name of the form hostname.port
45
10.8 ???? ?

• ???? ? ????
• ???? ? ?? ?? ?? ish
• ???? ? ???? ????(?)
• ish ??? ??? ??? ??? PATH ????? ????
• PATH ?? ????? setenv? ??? ?? ??
• ???? ? ??? control-D
• ?? ???
• ?? ???? P553

46
?? ?? ????

• ??? ?? ????
• netprog? talk_server.c talk_client.c ???? ??
• ??
• talk_server ????
• talk_client ?????IP?? ????
• ??? ?? ????
• ??? ????? ?? ?? ?? ??? ??????? ?? ??? ? ? ? ???
  accept() ?? read()?? ?? ???? ??(synchronous,
  blocking) ?? ?? select() ??? ??? ???? ???
  ???(asynchronous, non-blocking) ??? ??
• netprog? chat_server.c chat_client.c ?? ?? ??
• ??
• chat_server ????
• chat_client ?????IP?? ????

47
select()

• select()
• ???? ???? I/O ??? ????? ??? /O ??? ???? ?? ?
• ?? ?? s? ??? ??????? ??? I/O ?? ??
• select() ??? ?? ??
• int select (
• int maxfdp1, / chleo ??(? ??) ?? ?? 1 /
• fd_set readfds, / ?? ?? ??? ??? ?? ?? /
• fd_set writefds, / ?? ?? ??? ??? ?? ?? /
• fd_set exceptfds, / ?? ?? ??? ??? ?? ?? /
• struct timeval tvptr) /select() ??? ??? ????
  ?? /
• FD_ZERO(fd_set fdset) ???? ?? ?? ??
• FD_SET(int fd, fd_set fdset) ???? ?? fd? fdset
  ??? ???? ?? fdset ? fd? ???? ??? 1? ??
• FD_ISSET(int fd, fd_set fdset) ???? fdset? ?? fd
  ??? 1? ???? ??? ??? ????? fd?? fdset ??? ????? ??

48
X ??? ????? ??? ??

• X ??? ?????
• /usr/X/demo ??? ??
• puzzle
• spider
• xeyes
• xsol
• ?
• X manager http//www.netsarang.co.kr?? 30? ??
  ????
• Http//marvel.inchon.ac.kr/mysung ? Lecture
  Notes ? X Window Program ??
• Anonymous ftp multi cd pub/xprog ??
• ??? ??
• Http//marvel.inchon.ac.kr/mysung ? Lecture
  Notes ? System Administration ??

49
?? 12/23(?)??

• ?? 1 ??, ??, ? ??? ??? ??
• ? ?? ????? ?? ?? ???? ???? ??? ? ? ?? ??, ?? ?
  ??? ????.
• ? ??? ??? xx?? ?? ???? 5000 ??
• refree 5000
• ? ??? ??? yy?? ??
• player xx 5000
• ? ??? ??? zz?? ??
• player xx 5000
• ?? 2 ??? ?? ????
• ?? ??? ??? ?????? ??? ???? ??? ?? ?? ?? ??? ????
  ???? ??? ???? ?? ??????? ?? ?? ???? ?? ?? ?????
  ?? ???? ??? ??? ?? chat_server? chat_client ???
  ?? ????? ???? ??? ??, ? ?? ????? ?? ??? ??? ????
  ?who ??? ?? ??.
• ?? ?? ??
• ???? ???? ?? ?? 1023 lt ???? lt 5000
• ?? ?? ? ??? ?? ???? ?? kill -9 ??????(ps ????
  ???)

50
?! ???

• ???? ????.
• ???? ????? ??? ???? ???.
• ???? ?? ?? ??? ?? ?????. ??? ?? ???? ? ??? ????
  ??? ??? ?? ?? ??.
• ???? ???? ??? ???? ?? ??? ????.

?? ?????!