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
