17_高级进程间通信 UNIX域套接字1

非命名的UNIX域套接字

第1个参数domain，表示协议族，只能为AF_LOCAL或者AF_UNIX；

第2个参数type，表示类型，只能为0。

第3个参数protocol，表示协议，可以是SOCK_STREAM或者SOCK_DGRAM。用SOCK_STREAM建立的套接字对是管道流，与一般的管道相区别的是，套接字对建立的通道是双向的，即每一端都可以进行读写。不管是数据流还是数据报协议，unix域套接字都是可靠的，不丢包的。

第4个参数，用于保存建立的套接字对。

示例：

#include <stdio.h>    
#include <stdlib.h>    
#include <sys/socket.h>    
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
       
int main(void)  
{    
    int i_fd_arr[2];    
    int i_pid;    
    char psz_wbuf[16] = "0123456789";
    char psz_rbuf[16] = {0};
    
    if ( socketpair( AF_UNIX, SOCK_STREAM, 0, i_fd_arr ) < 0 )  
    {    
        perror( "socketpair" );
        return -1;
    }
  
    if ( ( i_pid = fork() ) < 0 )  
    {    
        perror( "fork" );
        return -1;
    }  
    else if ( 0 == i_pid )  
    {    
        //child    
        close( i_fd_arr[0] );    
        if ( write( i_fd_arr[1], psz_wbuf, strlen( psz_wbuf ) ) < 0 )  
        {
            perror( "write" );
            exit( -1 );
        }
 
        memset( psz_rbuf, 0, sizeof( psz_rbuf ) );
        if ( read( i_fd_arr[1], psz_rbuf, 16 ) < 0 )  
        {
            perror( "read" );
            exit( -1 );
        }
        printf( "child read: %s\n", psz_rbuf );
    }
    else
    {    
        //parent  
        close( i_fd_arr[1] );  
        if ( read( i_fd_arr[0], psz_rbuf, 16 ) < 0 )  
        {
            perror( "read" );
            exit( -1 );
        }
        printf( "parent read: %s\n", psz_rbuf );
 
        memset( psz_wbuf, 0, sizeof( psz_wbuf ) );
        strncpy( psz_wbuf, "9876543210", sizeof( psz_wbuf ) - 1 );
        if ( write( i_fd_arr[0], psz_wbuf, strlen( psz_wbuf ) ) < 0 )  
        {
            perror( "write" );
            exit( -1 );
        }
    }
    return 0;    
}    

命名UNIX域套接字

TCP示例：

server.c

#include <stdio.h>    
#include <sys/socket.h>    
#include <sys/un.h>    
#include <string.h>
#include <unistd.h>
    
int main(void)  
{    
    int i_listenfd = 0, i_clientfd = 0;       
    struct sockaddr_un addr_server, addr_client;    
    char psz_path[32] = "./server_unixsocket_file";
    int i_caddr_len = sizeof(struct sockaddr_un); 
    int i_saddr_len = sizeof(struct sockaddr_un);    
    char psz_rbuf[32] = {0};    
    char psz_wbuf[32] = "i am server.";
    int i_readlen = 0;
  
    //create a UNIX domain stream socket    
    if ( ( i_listenfd = socket( AF_UNIX, SOCK_STREAM, 0 ) ) < 0 )  
    {    
        perror( "socket" );
        return -1;
    }
  
    //in case it already exists    
    unlink( psz_path );    
  
    //fill in socket address structure    
    memset( &addr_server, 0, sizeof( addr_server ) );    
    addr_server.sun_family = AF_UNIX;
    strncpy( addr_server.sun_path, psz_path, sizeof( addr_server.sun_path ) - 1 );    
  
    //bind the name to the descriptor
    if ( bind( i_listenfd, ( struct sockaddr * )&addr_server, i_saddr_len ) < 0 )  
    {
        perror( "bind" );    
        return -1;    
    }    
  
    if ( listen( i_listenfd, 10 ) < 0 )
    {    
        perror( "listen" );
        return -1;
    }    
 
    while(1)
    {
        if ( ( i_clientfd = accept( i_listenfd, ( struct sockaddr * )&addr_client,
            ( socklen_t * )&i_caddr_len ) ) < 0 )  
        {    
            perror("accept");
            return -1;
        }    
        
        printf( "client is: %s\n", addr_client.sun_path );    
      
        if ( ( i_readlen = read( i_clientfd, psz_rbuf, sizeof( psz_rbuf ) - 1 ) ) < 0 )
        {
            perror( "read" );
            return -1;
        }
        psz_rbuf[i_readlen] = '\0';
        printf( "receive msg:%s\n", psz_rbuf );    
      
        if ( write( i_clientfd, psz_wbuf, strlen( psz_wbuf ) + 1 ) < 0 )  
        {    
            perror("write");    
            return -1;    
        }
    }
  
    unlink( psz_path );    
    return 0;    
}   

client.c

#include <stdio.h>    
#include <sys/un.h>    
#include <sys/socket.h>    
#include <string.h>
#include <unistd.h>
    
int main(void)  
{    
    int i_fd = 0;    
    struct sockaddr_un addr;    
    char psz_path[32] = "./client_unixsocket_file";    
    char serverpath[32] = "./server_unixsocket_file";    
    int i_addr_len = sizeof( struct sockaddr_un );    
    char psz_wbuf[32] = "i am client.";
    char psz_rbuf[32] = {0}; 
    int i_readlen = 0;
  
    if ( ( i_fd = socket( AF_UNIX, SOCK_STREAM, 0 ) ) < 0 )  
    {    
        perror("socket");
        return -1;
    }
  
    memset( &addr, 0, sizeof( addr ) );    
    addr.sun_family = AF_UNIX;
    strncpy( addr.sun_path, psz_path, sizeof( addr.sun_path ) - 1 );    
    unlink( psz_path );
  
    if ( bind( i_fd, ( struct sockaddr * )&addr, i_addr_len ) < 0 )  
    {    
        perror("bind");
        return -1;
    }
  
    //fill socket adress structure with server's address    
    memset( &addr, 0, sizeof( addr ) );    
    addr.sun_family = AF_UNIX;
    strncpy( addr.sun_path, serverpath, sizeof( addr.sun_path ) - 1 );    
  
    if ( connect( i_fd, ( struct sockaddr * )&addr, i_addr_len ) < 0 )  
    {
        perror("connect");
        return -1;
    }
  
    if ( write( i_fd, psz_wbuf, strlen( psz_wbuf ) + 1 ) < 0 )  
    {
        perror( "write" );    
        return -1;
    }    
  
    if ( ( i_readlen = read( i_fd, psz_rbuf, sizeof( psz_rbuf ) - 1 ) ) < 0 )  
    {    
        perror("write");    
        return -1;    
    }
    psz_rbuf[i_readlen] = '\0';
    printf( "receive msg:%s\n", psz_rbuf );    
    unlink( psz_path );
    return -1;
}    

UDP示例：

server

#include <stdio.h>      
#include <sys/socket.h>      
#include <sys/un.h>      
#include <string.h>  
#include <unistd.h>  
      
int main(void)    
{      
    int i_listenfd = 0/*, i_clientfd = 0*/;         
    struct sockaddr_un addr_server, addr_client;      
    char psz_path[32] = "./server_unixsocket_file";  
    int i_caddr_len = sizeof(struct sockaddr_un);   
    int i_saddr_len = 0;      
    char psz_rbuf[32] = {0};      
    char psz_wbuf[32] = "i am server.";  
    int i_readlen = 0;  
    
    //create a UNIX domain stream socket      
    if ( ( i_listenfd = socket( AF_UNIX, SOCK_DGRAM, 0 ) ) < 0 )  
    {      
        perror( "socket" );  
        return -1;  
    }  
    
    //in case it already exists      
    unlink( psz_path );      
    
    //fill in socket address structure      
    memset( &addr_server, 0, sizeof( addr_server ) );      
    addr_server.sun_family = AF_UNIX;  
    strncpy( addr_server.sun_path, psz_path, sizeof( addr_server.sun_path ) - 1 );      
    
    //bind the name to the descriptor  
    i_saddr_len = strlen( addr_server.sun_path ) + sizeof( addr_server.sun_family );  
    if ( bind( i_listenfd, ( struct sockaddr * )&addr_server, i_saddr_len ) < 0 )    
    {  
        perror( "bind" );      
        return -1;      
    }      
  
    while(1)  
    {  
        i_readlen = recvfrom( i_listenfd, psz_rbuf, sizeof( psz_rbuf ) - 1, 0,  
            ( struct sockaddr * )&addr_client, ( socklen_t *)&i_caddr_len );  
        if ( i_readlen < 0 )  
        {  
            perror( "read" );  
            return -1;  
        }  
        printf( "client is: %s\n", addr_client.sun_path );
        psz_rbuf[i_readlen] = '\0';  
        printf( "receive msg:%s\n", psz_rbuf );    
        
        if ( sendto( i_listenfd, psz_wbuf, strlen( psz_wbuf ) + 1, 0,  
            ( struct sockaddr * )&addr_client, i_caddr_len ) < 0 )  
        {  
            perror( "write" );  
            return -1;  
        }  
    }  
    
    unlink( psz_path );  
    return 0;      
}  

Client

#include <stdio.h>    
#include <sys/un.h>    
#include <sys/socket.h>    
#include <string.h>
#include <unistd.h>
    
int main(void)  
{    
    int i_fd = 0;    
    struct sockaddr_un addr;    
    char psz_clientpath[32] = "./client_unixsocket_file";    
    char psz_serverpath[32] = "./server_unixsocket_file";    
    int i_addr_len = 0;   
    char psz_wbuf[32] = "i am client.";
    char psz_rbuf[32] = {0}; 
    int i_readlen = 0;
  
    if ( ( i_fd = socket( AF_UNIX, SOCK_DGRAM, 0 ) ) < 0 )  
    {    
        perror("socket");
        return -1;
    }
    
    memset( &addr, 0, sizeof( addr ) );    
    addr.sun_family = AF_UNIX;
    strncpy( addr.sun_path, psz_clientpath, sizeof( addr.sun_path ) - 1 );    
    unlink( psz_clientpath );
    i_addr_len = strlen( addr.sun_path ) + sizeof( addr.sun_family );
    if ( bind( i_fd, ( struct sockaddr * )&addr, i_addr_len ) < 0 )  
    {    
        perror("bind");
        return -1;
    }
    
  
    //fill socket adress structure with server's address    
    memset( &addr, 0, sizeof( addr ) );    
    addr.sun_family = AF_UNIX;
    strncpy( addr.sun_path, psz_serverpath, sizeof( addr.sun_path ) - 1 );    
 
    i_addr_len = strlen( addr.sun_path ) + sizeof( addr.sun_family ); 
    if ( sendto( i_fd, psz_wbuf, strlen( psz_wbuf ) + 1, 0,
        ( struct sockaddr * )&addr, i_addr_len ) < 0 )  
    {
        perror( "write" );    
        return -1;
    }    
  
    if ( ( i_readlen = recvfrom( i_fd, psz_rbuf, sizeof( psz_rbuf ) - 1, 0,
        ( struct sockaddr * )&addr, ( socklen_t * )&i_addr_len ) ) < 0 )  
    {
        perror("write");    
        return -1;    
    }
    psz_rbuf[i_readlen] = '\0';
    printf( "receive msg:%s\n", psz_rbuf );    
    unlink( psz_clientpath );
    return -1;
}  

示例代码抄录自：https://blog.csdn.net/bytxl/article/details/47861469

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