TCP 粘包问题处理[2] ( the solution of sticky package problem of TCP )

Function :

In this passage , we offer another method to set out the sticky package. The method is that we encapsulate deadline function to realise to read by line. We set '\n' as the boundary of the message.

Server :

/**********************************************************************
> filename: echoserv2.c
> Author: ma6174
> Mail: ma6174@163.com
> Created Time: Thu 29 Oct 16:38:57 2015
************************************************************************/

#include <stdio.h>
#include <sys/socket.h>
#include <string.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#define ERR_EXIT(m) \
do \
{\
perror(m) ;\
exit(EXIT_FAILURE) ;\
}while(0)

//ssize_t the signed integer , size_t the unsigned integer
ssize_t readn ( int fd , void *buf , size_t count )   //encapsulate like read function
{
size_t nleft = count ;
ssize_t nread ;
char *bufp ;
bufp = ( char *) buf ;
while ( nleft > 0 )
{
//nread = read ( fd , bufp , nleft ) ;
//printf ("nread = %d\n" , nread ) ;
if ( (nread = read ( fd , bufp , nleft )) < 0  )
{
if ( EINTR  == errno ) // interrupted by the signal , we don't think this occasion is a mistake
{
continue ;
}
return -1 ;  		//failure
}
else if ( 0 == nread )  // peer close
{
return count - nleft ;
}
bufp += nread ;
nleft -= nread ;
}
return count ;
}

ssize_t writen ( int fd ,const void *buf , size_t count )
{
size_t nleft = count ;
ssize_t nwritten ;
char * bufp ;
bufp = (char*) buf ;
while ( nleft > 0 )
{
if ( ( nwritten = write ( fd , bufp , nleft ) ) < 0 )
{
if ( EINTR == errno )
{
continue ;
}
return -1 ;
}
else if ( 0 == nwritten )    // like nothing happened to write function
{
continue ;
}
bufp += nwritten ;
nleft -= nwritten ;
}
return count ;
}

ssize_t recv_peek ( int sockfd , void *buf , size_t len )
{
while ( 1 )
{
int ret = recv ( sockfd , buf , len , MSG_PEEK ) ;
//only let buf read the data from sockfd but not remove the data from that sockfd(socket)
//in comparison with read function it receive the data and remove the data in the socket
if ( -1 == ret && EINTR == errno )
{
continue ;			//interrupted by signal
}
return ret ;
}
}

ssize_t readline ( int sockfd , void *buf  , size_t maxline )
{
int ret ;
int nread ;
char *bufp ;
bufp = (char*) buf ;
int nleft ;
nleft = maxline ;
while (1 )
{
ret = recv_peek ( sockfd, bufp , nleft ) ;
if ( ret < 0 )    //failure
{
return ret ;
}
else if ( 0 == ret )		// peer closed
{
return ret ;
}
nread = ret ;
int i ;
for ( i = 0 ; i < nread ; i ++ )
{
if ( '\n' ==  bufp[i])
{
ret = readn (sockfd,bufp , i+1) ;
if ( ret != i + 1 )
{
exit(EXIT_FAILURE) ;
}
return ret ;
}
}
if ( nread > nleft )   // the data that we read(nread) can't be more than the real data in the socket
{
exit ( EXIT_FAILURE ) ;
}
nleft -= nread ;
ret = readn ( sockfd , bufp , nread ) ;  // read n characters from the socket ( don't contain '\n')
if ( ret != nread )
{
exit(EXIT_FAILURE ) ;
}
bufp += nread ;
}
return -1 ;
}

void do_service ( int conn )
{
char recvbuf[1024] ;
while(1)
{
memset ( recvbuf , 0 , sizeof(recvbuf) ) ;
int ret = readline ( conn , recvbuf , sizeof(recvbuf) ) ;
if ( -1 == ret )
{
ERR_EXIT("readline") ;
}
if ( 0 == ret )
{
//	ERR_EXIT ("client close\n") ;
printf("client close\n") ;
break ;
}
fputs ( recvbuf , stdout ) ;
writen ( conn , recvbuf , strlen(recvbuf) ) ;
}
}

int
main ()
{
int listenfd ;
if (( listenfd = socket ( PF_INET , SOCK_STREAM , IPPROTO_TCP )) < 0 )
{
ERR_EXIT("socket") ;
}
struct sockaddr_in servaddr ;
memset ( & servaddr , 0 , sizeof(servaddr ) ) ;
servaddr.sin_family = AF_INET ;
servaddr.sin_port = htons (5188) ;
servaddr.sin_addr.s_addr  = htonl(INADDR_ANY) ;		//INTADDR_ANY == 0

//other two means to change the host address to network address
//servaddr.sin_addr.s_addr = inet_addr("127.0.0.1") ;
//inet_aton("127.0.0.1" , &servaddr.sin_addr) ;

//set out the bind has already used by SO_REUSEADDR
int on = 1 ;
int opt ;
if (( opt = setsockopt (listenfd ,SOL_SOCKET , SO_REUSEADDR, &on , sizeof(on) )) < 0 )
{
ERR_EXIT("setsocketopt") ;
}
if ( bind ( listenfd , (struct sockaddr * ) &servaddr  , sizeof(servaddr )) < 0 )
{
ERR_EXIT("bind") ;
}
if ( listen ( listenfd , SOMAXCONN) < 0 )
{
ERR_EXIT("listen") ;
}
struct sockaddr_in peeraddr ;
socklen_t peerlen = sizeof(peeraddr) ;
int conn ;
while ( 1 )
{
if ( (conn = accept ( listenfd , ( struct sockaddr * )&peeraddr , &peerlen )) < 0 )
{
ERR_EXIT("accept") ;
}

// print the client's address and ip '
printf ("ip = %s port = %d\n", inet_ntoa(peeraddr.sin_addr) ,ntohs(peeraddr.sin_port) )  ;
int pid ;
pid = fork()  ;  // creat the child process to set out the multi-connection from clients
if ( -1 == pid )
{
ERR_EXIT ("fork") ;
}
if ( 0 == pid )
{
close (listenfd) ; // the son's pid didn't need to process the listen , so we close listenfd ;
do_service (conn) ;
exit(EXIT_SUCCESS) ;
}
else
{
close (conn) ;    // the father's pid didn't need  to process the acceept ,so we close conn '
}
}
return 0 ;
}

Client :

/************************************************************************
>file name : echocli.c
> Author: ma6174
> Mail: ma6174@163.com
> Created Time: Thu 29 Oct 16:38:57 2015
************************************************************************/

#include <stdio.h>
#include <sys/socket.h>
#include <string.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

#define ERR_EXIT(m) \
do \
{\
perror(m) ;\
exit(EXIT_FAILURE) ;\
}while(0)

//ssize_t signed integer   size_t unsigned integer
ssize_t readn ( int fd , void *buf , size_t count )    // encapsulate readn as the function of read
{
size_t nleft = count ;
ssize_t nread ;
char *bufp ;
bufp = ( char *) buf ;
//	printf ("nleft = %d\n" , nleft ) ;
while ( nleft > 0 )
{
//		printf ("nleft = %d\n" , nleft ) ;
nread = read ( fd , bufp , nleft ) ;
//                printf ("nread = %d\n" , nread ) ;
if( nread  < 0 )
{
if ( errno == EINTR )   // interrupted by signal , we don't think this occasion is not right
{
continue ;
}
return -1 ;
}
else if ( 0 == nread )    //peer closed
{
return count - nleft ;
//break ;
}
//		printf ("nreaad = %d\n" , nread ) ;
bufp += nread ;
nleft -= nread ;
}
return  count ;
}

ssize_t writen ( int fd , const void *buf ,size_t count )
{
size_t nleft = count ;
ssize_t nwritten ;
char *bufp ;
bufp = ( char * ) buf ;
while ( nleft > 0 )
{
if ( ( nwritten = write ( fd , bufp , nleft ) ) < 0 )
{
if ( errno == EINTR )  // just like the occasion in writen
{
continue ;
}
return -1 ;
}
else if ( 0 == nwritten  ) // if 0 == nread , like nothing happened to write ...
{
continue ;
}
bufp += nwritten ;
nleft -= nwritten ;
}
return count ;
}

ssize_t recv_peek ( int sockfd , void *buf , size_t len )
{
while ( 1 )
{
int ret = recv ( sockfd , buf , len , MSG_PEEK ) ;
//only let buf read the data from sockfd but not remove the data from that sockfd(socket)
//in comparison with read function it receive the data and remove the data in the socket
if ( -1 == ret && EINTR == errno )
{
continue ;			//interrupted by signal
}
return ret ;
}
}

ssize_t readline ( int sockfd , void *buf  , size_t maxline )
{
int ret ;
int nread ;
char *bufp ;
bufp = (char*) buf ;
int nleft ;
nleft = maxline ;
while (1 )
{
ret = recv_peek ( sockfd, bufp , nleft ) ;
if ( ret < 0 )    //failure
{
return ret ;
}
else if ( 0 == ret )		// peer closed
{
return ret ;
}
nread = ret ;
int i ;
for ( i = 0 ; i < nread ; i ++ )
{
if ( '\n' ==  bufp[i])
{
ret = readn (sockfd,bufp , i+1) ;
if ( ret != i + 1 )
{
exit(EXIT_FAILURE) ;
}
return ret ;
}
}
if ( nread > nleft )   // the data that we read(nread) can't be more than the real data in the socket
{
exit ( EXIT_FAILURE ) ;
}
nleft -= nread ;
ret = readn ( sockfd , bufp , nread ) ;  // read n characters from the socket ( don't contain '\n')
if ( ret != nread )
{
exit(EXIT_FAILURE ) ;
}
bufp += nread ;
}
return -1 ;
}

int
main ()
{
int sock ;
if (( sock= socket ( PF_INET , SOCK_STREAM , IPPROTO_TCP )) < 0 )
{
ERR_EXIT("socket") ;
}
struct sockaddr_in servaddr ;
memset ( & servaddr , 0 , sizeof(servaddr) ) ;
servaddr.sin_family = AF_INET ;
servaddr.sin_port = htons (5188) ;
//servaddr.sin_addr.s_addr  = htonl(INADDR_ANY) ;
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1") ;
//inet_aton("127.0.0.1" , &servaddr.sin_addr) ;
if ( connect ( sock , ( struct sockaddr * )& servaddr, sizeof(servaddr )) < 0 )
{
ERR_EXIT("connet") ;
}
char sendbuf[1024]={0} ;
char recvbuf[1024]={0} ;
memset ( sendbuf , 0 , sizeof(sendbuf) ) ;
memset ( recvbuf , 0 , sizeof(recvbuf) ) ;
int n ;
while( fgets ( sendbuf , sizeof(sendbuf) , stdin ) != NULL )
{
//fgets get the data with '\n' in default
writen ( sock , sendbuf ,strlen(sendbuf) ) ;     // the former 4 bytes and  the real data(n)
int ret = readline ( sock , recvbuf , sizeof(recvbuf) ) ;
if ( -1 == ret )
{
ERR_EXIT ("readline") ;
}
else if ( 0 == ret  )            //may interrupted by signal
{
printf ("clien________ close\n") ;
break ;
}
fputs ( recvbuf , stdout ) ;
memset ( sendbuf , 0 , sizeof(sendbuf) ) ;
memset ( recvbuf , 0 , sizeof(recvbuf) ) ;
}
close ( sock ) ;
return 0 ;
}