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 descriptorif ( 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
用于加深理解