本文主要是介绍命名UNIX域套接字通信，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
《UNIX环境高级编程》中开发的三个函数
#include "apue.h"
#include <sys/socket.h>
#include <sys/un.h>
#include <time.h>
#include <errno.h>#define STALE 30 /* client's name can't be older than this (sec) */#define QLEN 10#define CLI_PATH "./"
#define CLI_PERM S_IRWXU /* rwx for user only */
/** Wait for a client connection to arrive, and accept it.* We also obtain the client's user ID from the pathname* that it must bind before calling us.* Returns new fd if all OK, <0 on error*/
int
serv_accept(int listenfd, uid_t *uidptr)
{int clifd, err, rval;socklen_t len;time_t staletime;struct sockaddr_un un;struct stat statbuf;char *name;/* allocate enough space for longest name plus terminating null */if ((name = malloc(sizeof(un.sun_path + 1))) == NULL)return(-1);len = sizeof(un);if ((clifd = accept(listenfd, (struct sockaddr *)&un, &len)) < 0) {free(name);return(-2); /* often errno=EINTR, if signal caught */}/* obtain the client's uid from its calling address */len -= offsetof(struct sockaddr_un, sun_path); /* len of pathname */memcpy(name, un.sun_path, len);name[len] = 0; /* null terminate */if (stat(name, &statbuf) < 0) {rval = -3;goto errout;}#ifdef S_ISSOCK /* not defined for SVR4 */if (S_ISSOCK(statbuf.st_mode) == 0) {rval = -4; /* not a socket */goto errout;}
#endifif ((statbuf.st_mode & (S_IRWXG | S_IRWXO)) ||(statbuf.st_mode & S_IRWXU) != S_IRWXU) {rval = -5; /* is not rwx------ */goto errout;}staletime = time(NULL) - STALE;if (statbuf.st_atime < staletime ||statbuf.st_ctime < staletime ||statbuf.st_mtime < staletime) {rval = -6; /* i-node is too old */goto errout;}if (uidptr != NULL)*uidptr = statbuf.st_uid; /* return uid of caller */unlink(name); /* we're done with pathname now */free(name);return(clifd);errout:err = errno;close(clifd);free(name);errno = err;return(rval);
}/** Create a server endpoint of a connection.* Returns fd if all OK, <0 on error.*/
int
serv_listen(const char *name)
{int fd, len, err, rval;struct sockaddr_un un;if (strlen(name) >= sizeof(un.sun_path)) {errno = ENAMETOOLONG;return(-1);}/* create a UNIX domain stream socket */if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)return(-2);unlink(name); /* in case it already exists *//* fill in socket address structure */memset(&un, 0, sizeof(un));un.sun_family = AF_UNIX;strcpy(un.sun_path, name);len = offsetof(struct sockaddr_un, sun_path) + strlen(name);/* bind the name to the descriptor */if (bind(fd, (struct sockaddr *)&un, len) < 0) {rval = -3;goto errout;}if (listen(fd, QLEN) < 0) { /* tell kernel we're a server */rval = -4;goto errout;}return(fd);errout:err = errno;close(fd);errno = err;return(rval);
}/** Create a client endpoint and connect to a server.* Returns fd if all OK, <0 on error.*/
int
cli_conn(const char *name)
{int fd, len, err, rval;struct sockaddr_un un, sun;int do_unlink = 0;if (strlen(name) >= sizeof(un.sun_path)) {errno = ENAMETOOLONG;return(-1);}/* create a UNIX domain stream socket */if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)return(-1);/* fill socket address structure with our address */memset(&un, 0, sizeof(un));un.sun_family = AF_UNIX;sprintf(un.sun_path, "%s%05ld", CLI_PATH, (long)getpid());
printf("file is %s\n", un.sun_path);len = offsetof(struct sockaddr_un, sun_path) + strlen(un.sun_path);unlink(un.sun_path); /* in case it already exists */if (bind(fd, (struct sockaddr *)&un, len) < 0) {rval = -2;goto errout;}if (chmod(un.sun_path, CLI_PERM) < 0) {rval = -3;do_unlink = 1;goto errout;}/* fill socket address structure with server's address */memset(&sun, 0, sizeof(sun));sun.sun_family = AF_UNIX;strcpy(sun.sun_path, name);len = offsetof(struct sockaddr_un, sun_path) + strlen(name);if (connect(fd, (struct sockaddr *)&sun, len) < 0) {rval = -4;do_unlink = 1;goto errout;}return(fd);errout:err = errno;close(fd);if (do_unlink)unlink(un.sun_path);errno = err;return(rval);
}客户端：
#include "apue.h"
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
#include<errno.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <sys/un.h>
//#include<netinet/in.h>
#define UNIXSOCKETNAME "test_socket"
#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)
void echo_cli(int sock)
{char buf1[1024] = {0};char buf2[1024] = {0};int ret = 0;while(fgets(buf1, sizeof(buf1), stdin) != NULL){write(sock, buf1, strlen(buf1));ret = read(sock, buf2, sizeof(buf2));if(ret == 0){printf("server %d close\n", sock);break;}printf("%s", buf2);memset(buf1, 0, sizeof(buf1));memset(buf2, 0, sizeof(buf2));}close(sock);
}
int main()
{int sock = cli_conn(UNIXSOCKETNAME);if(sock < 0)ERR_EXIT("socket");echo_cli(sock);return 0;
}服务器端：
#include "apue.h"
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
#include<errno.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <sys/un.h>
#define ERR_EXIT(m) \do \{ \perror(m); \exit(EXIT_FAILURE); \} while(0)
#define UNIXSOCKETNAME "./test_socket"
void echo_cli(int sock)
{char buf[1024] = {0};int ret = 0;while(1){ret = read(sock, buf, sizeof(buf));if(ret == 0){printf("client %d close\n", sock);break;}printf("server receive %s \n", buf);write(sock, buf, strlen(buf));memset(buf, 0, sizeof(buf));}close(sock);
}
int main()
{int listenfd = serv_listen(UNIXSOCKETNAME);if(listenfd < 0)ERR_EXIT("socket");//unlink(UNIXSOCKETNAME);uid_t uidclient; int conn;pid_t pid;while(1){printf("server waiting ...\n");conn = serv_accept(listenfd, &uidclient); if(conn == -1){if(errno == EINTR)continue;ERR_EXIT("accept");}printf("Has new client connected, conn = %d\n", conn);pid = fork();if(pid < 0)ERR_EXIT("fork");else if(pid == 0){ echo_cli(conn);exit(1);}elseclose(conn);}return 0;
}
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