:

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 http://wist.ifmo.ru/info/index.html
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     .  
   .    
     .   
 .   ,  
     ,  
    .   
 : UNIX , Internet ,  ..


 Internet   -   IP    , 
        
Internet.  ,   -,   -,
   ,    ,
,  TCP.








 

      socket.


s = socket(domain, type, protocol);


         
.    Internet,   
 :




communication domain -

 AF_INET (Internet ).

type of the socket -

SOCK_STREAM;   
, ,   
   .


	      stream.    
  :



Datagram socket -

   . 
,     , ,
     .  
   ,    
.

Raw socket -

    
  , 
-.     -
.


	 socket       
 ,   ,  -1   . 
      .


	    stream   TCP, 
 ,   socket   :


s = socket(AF_INET, SOCK_STREAM, 0);







   


   .       , 
       , ,  
      . 
     .  Internet  
          
.       .


 Internet         , ,
 ,        
  ,    connect  send   
   ,        .


         
 bind:


bind(s, name, namelen);


  (name)     , 
  .  
    .





 


        
connect:


error = connect(s, serveraddr, serveraddrlen);


     ,    s
    serveraddr,   sockaddr_in, 
          . 
     , connect    
bind.


Connect  0,    .   -1
  ,        . 
         ,
  read  write,      close.


      .
       ,    
 ,    ,  
  .       listen:


error = listen(s, qlength);


 s   ,  qlength     
 ,     ,   ;
      .


	         
 ,         ,
 ' '.  Internet     
  .       accept:


newsock = accept(s, clientaddr, clientaddrlen);


,  ,  ,   
 accept,       
.


      1.




 IMAGE


. 1:    








 


  ,      
  .   ,    
     read  write:


write(s, buf, sizeof(buf));
read(s, buf, sizeof(buf));


 send  recv   read  write,  
,    .


send(s, buf, sizeof(buf), flags);
recv(s, buf, sizeof(buf), flags);


          ,
,  :







 


       
  ,     
,    "   
" (    FIN ).


    ,      
 close,      :


close(s);


     ,   (
 stream),       .  
,       ,  
   ,   .   
    ,      
 shutdown      .  shutdown 
""      .  
:


shutdown(s, how);


 how     :






 ,   WWW 


/*
-----------------------------------------------------------
  MakeConnection

  Function allocates a socket and estabishes a connection
  with remote host. Default port number 80.

  Input : WWW server name (with port number, if it is not 80)
  Output : file descriptor on success
              -1 on error

-----------------------------------------------------------
*/
int MakeConnection(unsigned char* ServerName){
  int s;
  struct sockaddr_in ssin;
  struct hostent* hp;
  int PortNum;
  unsigned char strHlp[STRNGLEN], *pch;

  /* use default port number - 80 or specific number from the
     server name */
  strcpy(strHlp,ServerName);
  pch = strchr(strHlp,':');
  if(pch==NULL){
    PortNum = 80;
  }else{
    pch[0] = '\0';
    pch++;
    PortNum = atoi(pch);
    if(PortNum==0){
      PortNum = 80;
    }
  }

  /* get host by name - resolve host name into IP address */
  if( (hp=gethostbyname(strHlp)) == NULL  )
  {
     return -1;
  }

  bzero(&ssin, sizeof(ssin));
  bcopy(hp->h_addr, &ssin.sin_addr, hp->h_length);
  ssin.sin_family = hp->h_addrtype;
  ssin.sin_port = htons(PortNum);

  /* allocate a socket */
  if((s=socket(AF_INET, SOCK_STREAM, 0))==-1)
  {
     return -1;
  }

  /* make a connection */
  if(connect(s, &ssin, sizeof(ssin), 0)==-1){

     return -1;
  }

  return s; /* socket descriptor */
}



Last-modified: Thu, 28 May 1998 14:26:10 GMT

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