happyzzzzz的专栏

family参数代表协议族,常用的协议族有，AF_INET、AF_INET6、AF_UNIX（或称AF_LOCAL，Unix域socket）、AF_ROUTE等等。协议族决定了socket的地址类型，在通信中必须采用对应的地址，如AF_INET决定了要用ipv4地址（32位的）与端口号（16位的）的组合、AF_UNIX决定了要用一个绝对路径名作为地址。

使用UNIX Domain Socket的过程和网络socket十分相似，但address family需指定为AF_UNIX

UNIX Domain Socket与网络socket编程最明显的不同在于地址格式不同，用结构体sockaddr_un表示，网络编程的socket地址是IP地址加端口号，而UNIX Domain Socket的地址是一个socket类型的文件在文件系统中的路径，，这个socket文件由bind()调用创建，如果调用bind()时该文件已存在，则bind()错误返回。

服务器端程序

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/un.h>#include <sys/socket.h>#include <syspes.h>#include <string.h>#define MAX_NUM 1024#define UNIX_ADDR "/tmp/cc_socket"int main(){ int server_sockfd,client_sockfd; int server_len,client_len; struct sockaddr_un server_address; struct sockaddr_un client_address; int i,ret; char ch_send,ch_rec; unlink(UNIX_ADDR); server_sockfd=socket(AF_UNIX,SOCK_STREAM,0); if(server_sockfd==-1) { perror("socket"); exit(1); } server_address.sun_family=AF_UNIX; strcpy(server_address.sun_path,UNIX_ADDR); server_len=sizeof(server_address); bind(server_sockfd,(struct sockaddr *)&server_address,server_len); listen(server_sockfd,MAX_NUM); printf("server waiting for client connect\n"); client_len=sizeof(client_address); client_sockfd=accept(server_sockfd,(struct sockaddr *)&client_address,(socklen_t *)&client_len); if(-1 != client_sockfd) printf("the server wait for client data\n"); for(i=0,ch_send='1';i<5;i++,ch_send++) {if((ret=read(client_sockfd,&ch_rec,1))==-1){perror("read");exit(1);}elseprintf("the character receiver from client is:%c\n",ch_rec);sleep(1);if(write(client_sockfd,&ch_send,1)==-1){perror("write");exit(1);} } close(client_sockfd); unlink("UNIX_ADDR"); return 0;}

客户端程序

#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/un.h>#include <sys/socket.h>#include <syspes.h>#include <string.h>#define UNIX_ADDR "/tmp/cc_socket"int main(){ int sockfd; int len; struct sockaddr_un address; int result; int i,ret; char ch_recv,ch_send; sockfd=socket(AF_UNIX,SOCK_STREAM,0); if(sockfd==-1) { perror("socket"); exit(1); } address.sun_family=AF_UNIX; strcpy(address.sun_path,UNIX_ADDR); len=sizeof(address); result=connect(sockfd,(struct sockaddr*)&address,len); if(result==-1) { printf("ensure the server is up\n"); perror("connect"); exit(1); } for(i=0,ch_send='A';i<5;i++,ch_send++){ if(write(sockfd,&ch_send,1)==-1) {perror("write");exit(1); } if(read(sockfd,&ch_recv,1)==-1) { perror("read"); exit(1); }else printf("receive from server is %c\n",ch_recv); } close(sockfd); return 0;}

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